Graphene Oxide and Visible Light:

An Advanced Platform for Water Disinfection

The debate surrounding water generally focuses mainly on its availability, but having the resource does not always ensure its good quality. Threats such as microbiological contamination, heavy metals, and organic compounds require the development of technologies capable of separating, transforming, or eliminating contaminants efficiently and sustainably.

In this context, graphene oxide (GO), a multifunctional nanomaterial derived from graphene and, at the same time, composed mainly of carbon atoms, exhibits a particularly attractive characteristic: a large surface area and interfaces capable of modifying physical and chemical phenomena at very small scales. Unlike graphene, GO contains oxygen-containing functional groups that promote its interaction with water and with different chemical species. Therefore, it can be used not only as an independent material, but also as a platform for constructing materials.

Real-World Applications of Multifunctional Materials 

The capacity to form hybrid materials opens the door to diverse applications across different sectors. However, to reach their full potential, it is necessary to develop research based on materials science and with a multidisciplinary approach that makes it possible to understand how, in this case, nanomaterials interact with living organisms and with contaminants in real-world environments.

A clear example of this approach is the doctoral thesis entitled “Photocatalytic Treatment of Biological Organisms in Water Using Graphene Oxide Doped with Titanium Dioxide (TiO₂) and Bismuth Vanadate (BiVO₄) Nanocomposites,” completed in 2021 by Dr. Christeena Theresa Thomas, under the supervision of Drs. Velumani Subramaniam and Benoît Schoefs. This was a collaborative project between the Center for Research and Advanced Studies of the National Polytechnic Institute (CINVESTAV-IPN, Mexico) and the University of Le Mans (France).

Use of Heterostructures for Water Disinfection 

To achieve water decontamination, the thesis strategy consisted of designing hybrid architectures (heterostructures) of graphene oxide with two light-sensitive semiconductor nanomaterials (TiO₂ and BiVO₄).

The objective of this integration was to leverage the electronic and surface properties of graphene oxide to efficiently channel and transport photogenerated electric charges, preventing this energy from dissipating. Optimizing the activation of the semiconductors through incident light (photocatalysis) triggers a chemical reaction in the water. This phenomenon uses light energy together with the catalyst material to destroy contaminants without being consumed in the process, generating highly decontaminating reactive oxygen species or free radicals.

“One aspect relevant to Mexican industry is that the graphene oxide used in the study was purchased from Energeia-Graphenemex (Mexico) and used as a raw material, without requiring any additional purification step.”

How Were the Heterostructures Prepared? 

The heterostructures were formulated by combining TiO₂ and BiVO₄ nanoparticles in graphene oxide dispersions at concentrations ranging from 0.5 to 2.5% by weight. Through the implemented methodology, the association of the semiconductor nanoparticles with the GO sheets was consolidated through noncovalent physical interactions, demonstrating that it is not always essential to resort to chemical functionalization of the material to give it a new function; instead, efficient hybrid architectures can be designed by strictly leveraging the complementary properties of each component.

“Heterostructure: a solid structure formed by joining two or more materials with different properties to create an interface with characteristics that none would have individually.”

Microbiological Inactivation 

When semiconductors are activated by light energy, they generate powerful oxidizing molecules known as reactive oxygen species (ROS), which are capable of destroying the cellular structures of contaminants.

However, not all materials respond to sunlight in the same way. For example, pure titanium dioxide (TiO₂) depends almost entirely on ultraviolet (UV) light, which represents only 4% of solar energy. BiVO₄, by contrast, can be activated by the visible region of the spectrum. Yet, although it is excellent at absorbing light economically and safely, it has the major disadvantage that its electric charges tend to recombine very quickly before they can act. It is at this point that graphene oxide was identified as having the potential to act as a platform that captures and stabilizes these charges to enhance disinfection.

To verify the efficiency of the heterostructures in eliminating pathogens, the inactivation of the model bacterium Escherichia coli K12 was evaluated.

The experiment consisted of exposing the nanocomposites to simulated visible light in contaminated aqueous suspensions, in order to measure the rate of microbial destruction and demonstrate the project’s potential as an ecological and environmentally friendly alternative. At the end of the process, the water was filtered through nylon membranes to recover the heterostructures.

Results 

Among the different formulations studied, the heterostructure containing 1.5% GO coupled with 98.5% TiO₂, at a dosage of 1.05 g/L, achieved 99.9% disinfection efficiency after 30 minutes of visible-light irradiation. In comparison, tests conducted using only TiO₂ (without GO) produced only approximately 20% disinfection over the same period.

Moreover, observations of the BiVO₄ heterostructures combined with 1.5% graphene oxide also yielded extremely interesting data. Although their disinfection efficiency was lower (89%) and required twice the irradiation time (60 minutes) compared with TiO₂, it is important to highlight the added value provided by the presence of GO in the heterostructure. That is, when BiVO₄ was evaluated individually (without GO), its effectiveness reached only 30%. Most noteworthy is that this result was achieved with an extremely small amount of material, using only 0.1 g/L in the solution, which represents one tenth of the dose used with TiO₂ (1.05 g/L).

These figures are proof of the synergistic effect between the materials, given that, thanks to the presence of graphene oxide, both semiconductors were transformed into highly efficient catalysts.

Microalgae Removal 

The excellent results obtained with the heterostructures against Escherichia coli K12 set the stage for taking the study to another level. That is, using the same mechanisms to solve the problems associated with uncontrolled microalgae growth.

When microalgae proliferate excessively in rivers, lakes, or coastal waters, they not only color the water, but also consume oxygen and, in many cases, release toxins that are dangerous to living organisms.

“Microalgae need light to survive, and nanomaterials require that same light to become activated and destroy them.”

Unlike the E. coli tests, for the microalgae tests, the study designed GO/TiO₂ pellets under extreme pressure; due to the density of the compacted material, when placed in the water, the pellets immediately settled to the bottom of the container and were activated with artificial light for 4 hours, while the algae floated on the surface. The species exposed were Anabaena (freshwater) and Phaeodactylum (a marine alga).

Results 

To scientifically demonstrate the death of the microalgae, the researchers analyzed chlorophyll fluorescence kinetics and induction. While the control group (not exposed to the pellets) maintained intact and stable chlorophyll levels under light, the samples exposed to the purifying pellets showed a drastic decline in fluorescence.

Likewise, the definitive comparison was made after allowing a full night to pass in complete darkness. The following day, the control group immediately recovered its ability to photosynthesize when exposed to light, whereas the microalgae that had been in contact with the graphene oxide and titanium pellets showed no sign of cellular life, demonstrating that their destruction had been complete and irreversible.

Finally, a highly relevant finding from an ecological perspective was the reusability of the pellets after several cycles of activation and water purification. However, material detached from the pellet was observed, probably as a consequence of erosion. This demonstrates that, although compaction represents a promising strategy for facilitating recovery of the nanomaterial, mechanical stability and material release are points to consider prior to large-scale application.

Conclusion 

This research demonstrates that graphene nanotechnology has real potential for use as a platform for designing photocatalytic materials capable of significantly increasing the activity of certain semiconductors.

In this research, the graphene oxide supplied by the Mexican company Energeia-Graphenemex had significant value as a raw material for the development of the heterostructures studied. Although the company was not involved in the development or execution of the research, the fact that the study used graphene oxide produced through an established industrial process represents an element of interest for the continuity and maturation of this line of research.

Having a nanomaterial that can already be produced at industrial scale allows future stages to begin with an available and reproducible product, rather than depending exclusively on material synthesis at laboratory scale. This opens the possibility of continuing to study the same formulations, optimizing their performance, and evaluating their behavior under conditions that are increasingly closer to a real-world application.

In this way, the availability of nanostructured products such as those developed by Energeia-Graphenemex can help bridge the gap between laboratory research and technological development, providing a materials platform on which to continue exploring advanced applications for water treatment and disinfection.

Prepared by: EF/Dania Hernández 

References

1. Thomas, C.-T., Ravichandran, M., Santoyo-Salazar, J., Schoefs, B., Velumani, S., Castaneda, H., & Jantrania, A. (2021). Graphene oxide decorated TiO₂ and BiVO₄ nanocatalysts for enhanced visible-light-driven photocatalytic bacterial inactivation. Journal of Photochemistry and Photobiology A: Chemistry, 418, 113374. 10.1016/j.jphotochem.2021.113374

The future of water is nano:

How graphene is revolutionizing industrial filtration.

Graphene materials are a family of carbon nanostructures organized in a sheet-like hexagonal pattern, which are in turn classified according to the number of layers, morphology, and surface chemistry. However, the most well-known is graphene, which essentially consists of carbon atoms, famous for its high mechanical strength, among many other thermal, electrical properties, etc., and graphene oxide which, in addition to carbon, contains oxygenated functional groups that favor its interaction with water and other substances. 

In the water technology sector, graphene materials are transforming the design of nanotechnological filtration barriers. By being integrated into the modification of both filters and membranes, graphene has the challenge of meeting two major objectives: The first is to optimize selectivity, that is, to improve control over the components that manage to pass through the barrier and those that are rejected. This is achieved through the creation of nanochannels between the sheets that limit the passage of contaminants by size exclusion, or rather, through chemical adsorption mechanisms. The second objective is to maximize filtration efficiency. When incorporated into the structure, graphene reinforces the mechanical properties of the base polymers and provides notable resistance to fouling (antifouling). Consequently, these improvements mitigate the pressure drop, maintain a constant water flow, and reduce energy consumption during system operation. 

Are there filters and membranes made solely of graphene? 

A frequent mistake is to think that a filtering material can be manufactured solely with graphene. This is because, although this family of nanomaterials is sheet-shaped, its size is so small that, in order to be used as a membrane or filter, it is necessary to immobilize them on a porous support or incorporate them into a polymeric matrix. Therefore, it is most convenient to conceive these nanostructures as materials capable of modifying or complementing the properties of pre-existing materials, but from a nano perspective. 

“A nanometer is equivalent to 0.000001 millimeters” 

“The difference between a filter and a membrane lies in the pore size, the contaminant separation mechanism, and the pressure required to operate the system” 

How are graphene materials integrated into a filtering material? 

In the race to achieve the objectives, the scientific community has studied different methods to incorporate graphene into filters and membranes. Some methodologies are relatively simple and fast, while others require more complex processes. 

The most common reported methods are: 

1. Filtration deposition 

It consists of preparing a dispersion of graphene material at a known concentration, to later filter it with a commercial membrane (e.g., polysulfone, polyamide, polyvinylidene fluoride (PVDF), polyethersulfone (PES), cellulose or nylon). During the process, the graphene material nanoparticles randomly arrange themselves, forming an ideally continuous film on the base polymer. 

2. Dip coating 

It consists of introducing a commercial membrane, like those mentioned in the previous method, into a dispersion of graphene material for a certain time. The immersion aims for the nanoparticles to adsorb onto the membrane to form a film. 

These first two methods are probably the most used in the laboratory. They are simple and fast procedures, but with the disadvantages of being difficult to scale, not very stable, and not very uniform. Although with the advantage of providing relevant information about the behavior of each material. 

3. Layer-by-layer 

With this technique, more ordered structures are formed, as it consists of depositing intercalated layers of positively and negatively charged graphene material. 

Among its advantages is excellent control of thickness, uniformity, and selectivity. In fact, this method has shown interesting results for applications that require greater selectivity and resistance to fouling. However, the manufacturing process is relatively slow for mass production; it requires additional chemical modifications to the nanomaterial to change its charge, and the membrane can be so compact that the water flow is likely limited. 

4. Direct blending with polymers 

In industrial terms, this method is the alternative with the greatest potential. Instead of depositing the graphene material on a finished product, the strategy is to take advantage of existing processes and infrastructure to incorporate the nanomaterial during the manufacture of the filtering material. In this way, graphene is integrated throughout the architecture of the final product from its origin. 

“The challenge of graphene is not to prove whether it works or not inside a laboratory, but to integrate it into industrial processes.” 

From the laboratory to the market 

Fortunately, today, talking about graphene or graphene materials in real applications is no longer a milestone of the future, in fact, it is a reality that is transforming industries. So much so, that starting in 2022, industrial filters, portable cartridges, and graphene-based nanofiltration systems for water purification and contaminant removal began to enter the market. However, although this transition from the laboratory to the industry is a big leap, there are still few companies that have managed to bring this technology to industrial production, for example: 

• Clean TeQ Water (Australia): Through its subsidiary NematiQ, it manufactures rolls of graphene oxide nanofiltration membranes for treatment plants; 

• Medica S.p.A. (Italy): With a medical and domestic focus, it operates through its Graphil line; 

• Icon Life Saver (United Kingdom): Developed Graphene:Ultra portable cartridges for the removal of heavy metals and chemicals; 

• GYC Group (Asia): Provides composite filters and customized graphene additives. 

Despite these success stories, the supply remains small for such high need and demand. 

In this context, research carried out at the Autonomous University of San Luis Potosí (UASLP), under the direction of Dr. Mildred Quintana, studied the potential of different combinations of graphene materials for water filtration. The study entitled “Design of graphene nanocomposites for the development of membranes” was carried out as part of a 2025 doctoral thesis. The research compared the performance of graphene oxide and graphene heterostructures synthesized in the laboratory, with their counterpart designed from materials produced industrially by Graphenemex®. 

The research was developed in two stages. First, the heterostructures synthesized in the laboratory were designed and studied to obtain reference data, and subsequently, their counterparts were prepared with Graphenemex® materials. The heterostructures were immobilized on PTFE and polyester supports by filtration, to then evaluate their performance regarding water permeation, dye removal, Na⁺ and Cl⁻ rejection, among other evaluations. 

The comparison between both systems was made to determine if the materials produced industrially by Graphenemex® could reproduce the results offered by the heterostructures synthesized under controlled laboratory conditions. 

“The materials produced by Graphenemex® retained the ability to interact and form functional heterostructures” 

The results obtained are relevant because, within the different systems studied in the thesis, selectivities greater than 80% and permeances greater than 2500 L/(m²·h·bar) were achieved. These data coincide with other studies in which GO membranes deposited on nylon membranes have achieved rejections greater than 90% for organic molecules. 

It should be clarified that the results of the thesis do not represent a finished commercial membrane, but they are part of a fundamental stage on the path to its technological maturation with 100% Mexican science and technology. The next step is to perfect this knowledge and transfer it to an increasingly relevant environment. In this case, through the immobilization of the heterostructures in a filtering material. 

At Graphenemex®, we feel very proud of the possibility of being part of a solution to such an important global problem. The development of these technologies is not just an engineering achievement, it is a commitment to the planet and future generations.

From the Laboratory to Industry:

How Graphenemex Graphene Drives Innovation in Mexico (Part II) 

In Part I of this article, we discussed how incorporating graphene into a product or process does not begin with a formulation or the purchase of a nanomaterial, but rather with the willingness to innovate. 

If a company or prospective customer has identified a challenge that could potentially be solved through the use of graphene, and there is a willingness to invest time, resources, and human talent in a research and development process, a new question naturally arises: 

How do I get started? 

The answer is straightforward, although it requires commitment, collaboration, and work. The following outlines the development pathway that Graphenemex® has built through more than ten years of experience producing graphene-based materials and collaborating with different industries in the adaptation and implementation of this technology. 

Understanding Graphene and Its Possibilities 

Before attempting to initiate experimental trials, it is important for the interested party to understand, at least in general terms, what graphene is, what distinguishes its different forms, and what types of benefits it can provide. It is not necessary to become a graphene specialist. Graphenemex® offers complete openness and technical support precisely for that purpose. However, it is highly recommended to involve personnel from technical, research and development, quality assurance, and production departments in order to address questions and gain a clear understanding of the actual capabilities and limitations of this technology. 

Likewise, Graphenemex® needs to understand the general characteristics of the client’s process. To this end, it is useful to share information related to the raw materials employed, formulations and general manufacturing processes, quality control methods, as well as the regulations or specifications that the final product must satisfy. It is not necessary to disclose trade secrets or complete formulations; however, sufficient information should be provided to enable an understanding of the system into which graphene is intended to be incorporated. 

Information Protection 

Depending on the nature of the project, it may be advisable to formalize Non-Disclosure Agreements (NDAs) before exchanging detailed technical information. These agreements help protect both the client’s proprietary knowledge and developments, as well as the methodologies, materials, and accumulated expertise of Graphenemex®. Confidentiality promotes a more open and efficient collaboration, allowing information to be shared without compromising the intellectual property of either party. 

Material Selection 

The term graphene encompasses an entire family of carbon-based materials. Its most widely recognized variants include graphene itself, graphene oxide, and reduced graphene. However, this family is considerably broader than what is commonly described in the literature as standard materials. This is because each producer employs its own synthesis methodology, with or without additional functionalization processes. It is precisely at this point that differences become most evident when the development stage begins. 

As Graphenemex® manufactures its own graphene-based materials, it can recommend the material type with the highest probability of success for a particular application. In some cases, conventionally produced graphene materials can interact adequately with the customer’s matrix without requiring additional modifications. This is particularly important because it can significantly reduce both development time and costs. However, when compatibility is limited, the possibility of performing surface chemical modifications or employing coupling agents to promote interaction with the raw materials used can be evaluated.

Compatibility Testing 

To fully leverage graphene’s characteristics, it must be integrated into a three-dimensional matrix capable of maintaining it in a dispersed and stabilized state, thereby enabling the balanced transfer of its properties throughout the system. 

Consequently, this stage seeks to identify which of the raw materials present in the formulation can serve as a carrier or vehicle to facilitate the integration of graphene into the matrix. Likewise, this phase often provides guidance regarding the most appropriate stage or portion of the manufacturing process for incorporating graphene into the system. 

Exploratory Trials 

Once the most compatible material or materials have been identified, it is important to conduct small-scale exploratory trials to evaluate different graphene concentrations, as well as alternative integration methods for the new system or product. 

This is necessary because, just as there is no single type of graphene, there is also no standard dosage or universal method for taking advantage of its properties. The good news is that, in many polymer systems, coatings, and resin-based formulations, very low graphene loadings by weight are often sufficient to produce significant improvements, provided that the graphene is properly distributed throughout the supporting matrix. 

Testing Under Relevant Operating Conditions 

After identifying the most compatible graphene material and the effective dosage range at laboratory scale, it becomes possible to schedule trials under actual processing conditions while monitoring the quality parameters normally used by the customer. 

In this regard, the development of graphene-based applications should be understood as a shared learning process in which the customer contributes expertise regarding their product, while Graphenemex® contributes its experience in graphene technology. The combination of these complementary capabilities is what ultimately makes it possible to address a real challenge or achieve a specific development objective. 

Graphene in Agriculture:

The Silent Revolution That Will Feed the World 

Optimizing food production with fewer resources and minimal environmental impact remains a constant challenge for agriculture in the face of growing global demand. In this context, over the past decade, experts in nanotechnology have initiated multiple research lines focused on graphene, aiming to generate evidence of its effects on plant species and, consequently, evaluate its feasibility for subsequent use in the agricultural industry. 

What is the importance of graphene for agriculture? 

From a physicochemical standpoint, graphene is a two-dimensional sheet of carbon atoms arranged in a hexagonal lattice, only one atom thick. This seemingly simple structure is responsible for its extraordinary properties, including electrical and thermal conductivity, mechanical strength, hydrophobicity, among many others, which collectively are unmatched by any other material.  

“Surface chemistry, concentration, and interaction mechanisms of graphene are critical factors for improving agricultural productivity.” 

On the other hand, graphene oxide (GO) is the most extensively studied variant due to its surface chemistry, characterized by the presence of hydroxyl, epoxide, carbonyl, and carboxyl groups. These functional groups transform graphene’s inherently hydrophobic nature into a hydrophilic form, enabling not only the formation of stable and biocompatible aqueous dispersions but also converting it into a chemical exchange platform capable of anchoring nutrients, capturing contaminants, and interacting with other nanoparticles, molecules, or components of agricultural interest. 

A practical example is the potential of GO as a fertilizer coadjuvant. As is well known, one of the major issues with fertilizers is their low efficiency, since a significant portion volatilizes or leaches, contaminating water bodies and soils. In this case, it is hypothesized that the functional groups distributed across the graphene surface can encapsulate nutrients and subsequently release them gradually, preventing losses and, consequently, reducing environmental contamination.  

“While graphene provides the structural foundation and physical properties, it is graphene oxide that enables its practical use in agriculture, as it translates graphene’s properties into a language that living systems can understand.” 

Below is a chronological overview of some of the most relevant advances in graphene research applied to agriculture: 

Between 2010 and 2012, researchers in China and the United States studied the impact of GO on lettuce, rice, and tomato crops. By exposing seeds to aqueous solutions containing 0.001 to 0.1 g/L of GO, the primary objective was to determine its penetration capacity and possible effects on germination. Surprisingly, scientists observed that at low concentrations, GO enhanced germination, root growth, and photosynthesis, possibly by facilitating water uptake and triggering enzymatic activation. 

Between 2013 and 2016, research continued to better explain these phenomena. Instead of merely exposing seeds to GO dispersions, scientists designed experiments that incorporated environmental variables, such as plant growth in pots. This allowed the analysis of factors like water availability and nutrient dynamics, leading to the conclusion that graphene oxide could indeed retain water, improve seed hydration, and adsorb nutrients, keeping them available near the root zone. In other words, GO was found to optimize the plant microenvironment. 

Given these findings, it became evident that studies needed to be conducted in more representative environments. Thus, between 2016 and 2019, researchers in India and China extended experiments to greenhouses, hydroponic systems, and full crop cycles, particularly in rice and wheat. They evaluated biomass, photosynthesis, and even quantified plant hormones. Results consistently showed that GO acted as a biostimulant, promoting growth and improving photosynthetic efficiency. 

With so many positive outcomes, the focus shifted from whether graphene enhanced plant growth to whether it could help plants survive under adverse conditions. Consequently, between 2019 and 2021, researchers in the United States and Europe discovered that GO not only promotes growth but also enhances plant survival under drought and salinity stress, as explained below:

Salinity 

To simulate saline conditions, sodium chloride solutions ranging from 50 to 120 mM were used to induce water loss, ionic imbalance, and oxidative stress in plants. Importantly, in the presence of GO—whether applied to soil, via foliar spraying, or in hydroponic systems—plants maintained ionic balance, increased antioxidant enzyme activity, and preserved photosynthetic performance. 

Drought 

Various methodologies are typically used to simulate drought conditions, such as reducing or suspending irrigation, or employing agents like polyethylene glycol to lower water potential without physically removing water. In all cases, GO integration follows a similar approach: direct application to the soil, followed by evaluation of plant responses. One key observation was that under drought conditions, GO does not always internalize within the plant but may remain in the soil, retaining water, reducing evaporation, and increasing water availability duration. In this sense, GO can function as a soil conditioner. 

Oxidative Stress 

In summary, both salinity and drought induce oxidative stress in plants, defined as an imbalance caused by excessive reactive oxygen species (ROS), commonly known as free radicals, which can lead to cellular damage or death. In this context, studies indicate that while GO does not prevent stress factors, it enhances plant resilience by activating antioxidant enzymes, retaining water, enabling osmotic adjustment, and regulating hormonal responses. 

Thus, between 2022 and 2025, particularly in India, the concept of “nano-priming” emerged. This technique involves the preconditioning of seeds or plants through controlled hydration to activate their metabolism prior to actual growth, with the aim of improving germination and stress tolerance. To date, nano-priming with GO has demonstrated improved germination rates, stronger root systems, activation of antioxidant defenses, and enhanced stress response. 

With all these scientific advances, graphene oxide is increasingly consolidating its role as a key agricultural tool to improve soil microenvironment conditions, optimize water usage, and strengthen crop resilience. 

Consequently, Energeia-Graphenemex reaffirms its commitment to Mexican innovation through a collaboration with the Bionanotechnology Laboratory of the Institute of Physics (UASLP), led by Dr. Daniela Salado. Within the framework of the Institutional Doctorate in Materials Science and Engineering (DICIM-UASLP), and with the participation of student Sarahi Josefina Estrada Loredo, a research line was launched in 2025 to analyze the interaction of nanomaterials—including graphene and graphene oxide (Graphenemex®)—with strategic crops. We look forward to sharing the results of this important project in the near future. 

Editing:  EF/Dania Hernández 

References 

1. Niu, Y.-X., Yao, X.-Y., Won, J. H., Shen, Z.-K., Liu, C., Yin, W., Xia, X., & Wang, H.-L. (2026). Application of graphene oxide nanomaterials in crop plants and forest plants. Forests, 17(1), 94. https://doi.org/10.3390/f17010094 

2. Chen, Z., Zhao, J., Cao, J., Zhao, Y., Huang, J., Zheng, Z., Li, W., Jiang, S., Qiao, J., Xing, B., & Zhang, J. (2022). Opportunities for graphene, single-walled and multi-walled carbon nanotube applications in agriculture: A review. Crop Design, 1, 100006. https://doi.org/10.1016/j.cropd.2022.100006 

3. Yang, Y., Zhang, R., Zhang, X., Chen, Z., Wang, H., & Li, P. C. H. (2022). Effects of graphene oxide on plant growth: A review. Plants, 11(21), 2826. https://doi.org/10.3390/plants11212826 

Carbonation and Graphene Oxide:

A Solution for Reducing CO₂ Emissions

In previous articles, we discussed the cement industry’s impact on CO₂ emissions and the commitments made to reduce them by 2050. Today, we explore how carbonation—a process generally seen as a concrete pathology—could help offset some CO₂ emissions from cement production.

What is Carbonation?

In concrete, carbonation is a natural process where CO₂ from the environment reacts with moisture in the concrete, converting the alkaline calcium hydroxide in cement paste to calcium carbonate with a more neutral pH. This reaction lowers the concrete’s pH from around 12–13 to approximately 9, exposing steel reinforcements to corrosion.

What Affects Carbonation?

Carbonation rate depends on the diffusion of CO₂ and its reactivity with the cement matrix, which is in turn influenced by the matrix’s microstructure, hydration products (calcium hydroxide, calcium silicate hydrate, alkaline oxides, etc.), and pore structure (distribution, size, and saturation). Therefore, carbonation proceeds more slowly in low-permeability or dry concretes than in permeable ones with 50–60% humidity. To reduce porosity and calcium hydroxide levels, micrometric additives like fly ash, blast furnace slag, metakaolin, silica fume, and some nanomaterials are used during concrete production, alongside practices like applying surface coatings.

Carbonation as an Emission Reduction Tool

Carbonation can be viewed in two ways: first, as a concrete pathology, and second, as a CO₂-reducing opportunity. There are two types of carbonation: natural and accelerated. Natural carbonation is slow and does not capture CO₂, while accelerated (or mineral) carbonation uses high CO₂ concentrations, speeding up cement hydration and producing carbonates in which CO₂ is permanently stored in a thermodynamically stable mineral form. This process, known as recarbonation, involves the same carbonate used as a raw material in cement production. Companies like Blue Planet, Carbon Cure, Solidia Technologies, and Carbi Crete are developing strategies to sequester up to 17 kg of CO₂ per cubic meter of prefabricated concrete, as this process requires controlled conditions.

Graphene Oxide (GO) and Its Impact

Graphene oxide (GO) is a carbon nanostructure whose multifunctionality offers numerous benefits across industries. In concrete, GO enhances mechanical strength and durability, though its effects on carbonation and CO₂ capture are less well-documented.

Research conducted by the University of Arlington, Texas, in 2022 examined GO’s interaction mechanism in concrete cured under accelerated carbonation. Results indicated that GO, by improving cement hydration, refines concrete pores with calcium carbonate precipitated on hydration products and cement particles, limiting chemical reactions between hydration products and CO₂ under continuous CO₂ flow. The study concluded that GO not only enhances concrete’s mechanical properties but also helps capture and store up to 30% of atmospheric CO₂ during early curing stages.

Authored by: EF/ DHS

References

1. Geetika Mishra, et al., Carbon sequestration in graphene oxide modified cementitious system, Journal of Building Engineering, 2022, 62, 105356;
2. Nur Azni Farhana Mazri et al., Graphene and its tailoring as emerging 2D nanomaterials in efficient CO2 absorption: A state-of-the-art interpretative review. Alexandria Engineering Journal, 2023, 77, 479;
3. Mohd Hanifa et al., A review on CO2 capture and sequestration in the construction industry: Emerging approaches and commercialised technologies, Journal of CO2 Utilization, 2023, 67, 102292;
4. Yating Ye et al., Optimizing the Properties of Hybrids Based on Graphene Oxide forCarbon Dioxide Capture, Ind. Eng. Chem. Res. 2022, 61, 1332;
5. Sanglakpam Chiranjiakumari Devi et al., Influence of graphene oxide on sulfate attack and carbonation of concrete containing recycled concrete aggregate, Construction and Building Materials, 2020, 250, 118883

The Impact of Graphene on the Plastic Industry:

Innovation and Sustainability

The origins of plastic trace back to 1860 in the United States when Phelan & Collander, amid an ivory shortage—a material widely used for billiard balls, piano keys, jewelry, and decorative structures—announced a call for a material capable of replacing ivory, offering substantial financial compensation for the time. John Wesley Hyatt proposed “celluloid,” a plant-based carbohydrate that, while not fully replacing ivory, became the stepping stone for the development of plastic, with immediate successors like Bakelite and PVC leading to today’s engineering plastics.

The term “plastic” comes from the Greek “plastikos,” meaning “moldable.”

Plastics are synthetic materials obtained through various polymerization processes from petroleum derivatives. Their evolution and refinement have made them essential to numerous industries and activities. However, after years of unchecked use, plastics have become both a solution for many needs and a significant environmental and health issue, as their versatility and demand have also led to increased waste. As a result, the not-so-new philosophy of sustainable circularity, or the circular economy, involves not only awareness of resource use but also economic, infrastructure, and recycling process adaptations.

Recycling involves reprocessing used materials, such as plastics, for reuse. While an excellent tool for preserving natural resources and reducing waste, two key points must be considered. First, recycling doesn’t apply in all cases because not all plastics are recyclable. Second, reprocessing involves stages where materials may lose properties compared to virgin plastics, limiting their use in many industrial applications.

Over the past 20 years, nanotechnology’s intervention in modifying polymers like polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), among others, with carbon nanoparticles like graphene or carbon nanotubes (CNTs), has yielded interesting results regarding improved mechanical, rheological, electrical, and thermal properties. Graphene’s advantage over CNTs, in addition to other intrinsic properties, lies in its sheet-like structure, whose large surface area and greater dispersibility allow it to create more homogeneous phases, improving load transfer and thereby increasing the mechanical strength of modified plastics.

Companies such as Gerdau Graphene (Brazil), Graphenetech S.L. (Spain), Colloids (UK), and Energeia-Graphenemex (Mexico) have positioned various types of graphene-based masterbatches or concentrated plastics in the market over the past five years. Although each company has its own objectives and markets, there are environmental and economic points of convergence that motivated them to improve the plastic industry. Graphene, even in low concentrations (< 2% by weight), can enhance the quality of both virgin and recycled polymers. For example, graphene can increase flexural modulus by 30%, impact resistance by 40%, tensile strength by 17%, and resistance to rupture by 60%. It can also improve resistance to photodegradation. Depending on the specific needs of each development or application, it is possible to restore some of the mechanical properties of recycled plastics and/or extend the material’s lifespan to reduce the circulation of single-use plastics or, alternatively, achieve the same mechanical properties of polymers with reduced thickness.

Energeia – Graphenemex®, the leading Mexican company in Latin America in graphene material research and production for industrial applications, launched a wide range of graphene-based masterbatches in 2023 through its Graphenergy Masterbatch line, designed to be used as multifunctional reinforcement additives. Key advantages include:

• Excellent dispersion within the polymer matrix
• Can be incorporated into recycled polymers
• Increase tensile, deformation, and impact resistance
• Improve resistance to ultraviolet rays
• Facilitate processing conditions (thermal stability)
• Act as nucleating agents (modify polymer crystallization temperature).

Drafting: EF/DHS

References:

1. Ramazan Asmatulu et al., Synthesis and Analysis of Injection-Molded Nanocomposites of Recycled High-Density Polyethylene Incorporated With Graphene Nanoflakes, POLYMER COMPOSITES—2015;
2. Feras Korkees et al., Functionalised graphene effect on the mechanical and thermal properties of recycled PA6/PA6,6 blends. 2021 Journal of Composite Materials 55(16);
3. Devinda Wijerathne et. al., Mechanical and graphe properties of graphene nanoplatelets-reinforced recycled polycarbonate composites. International Journal of Lightweight Materials and Manufacture 6 (2023) 117e128;
4. Abdou Khadri Diallo et al., A multifunctional additive for sustainability, Sustainable Materials and Technologies, 33, 2022, e000487.

Innovation with Graphene:

Towards a More Sustainable and Efficient Cement Industry

Part 1

Carbon dioxide (CO2) is a colorless, odorless, and non-toxic gas naturally present in the atmosphere. Under normal conditions, it should remain balanced to retain the heat necessary for human survival without becoming a greenhouse gas. However, overpopulation, industrialization, and environmental exploitation have disrupted this balance, making CO2 levels increasingly difficult to control. Consequently, these levels rise, concentrate, absorb radiation, and prevent heat from escaping, contributing to global warming.

According to statistics, cement production and the fossil fuel industry (coal, oil, and natural gas) are responsible for releasing about 90% of CO2 and probably 70% of greenhouse gases. Other industries, such as agriculture, fashion, and transportation, also contribute.

“Sustainability of our civilization depends on whether we can provide energy, food, and chemicals to the growing population without compromising the long-term health of our planet.” Doria-Serrano, 2009.

Concerning cement, the main component of concrete, reports mention that it alone accounts for between 7% and 8% of global CO2 emissions. For reference, producing one ton of clinker, the main component of cement, releases approximately ~0.86 tons of CO2, of which around 60% comes from the transformation of limestone into calcium oxide or lime at an average temperature of 1450 °C, a process also known as clinker burning. The remaining 40% is attributed to the combustion of fossil fuel (coal) necessary for the calcination of limestone and clinker formation.

“In 2021, carbon emissions from cement production reached nearly 2,900 million tons of carbon dioxide, while in 2002, 1,400 million tons were recorded.” The Global Carbon Project.

Therefore, to achieve the net-zero emissions target by 2050 required by the Paris Agreement, the cement industry has been forced to take measures to reduce its impact by using alternative fuels (biomass, tires, urban solid waste); improving energy efficiency by reducing the clinkerization temperature through fluxes and mineralizers (such as CaF2, BaO, SnO2, P2O5, Na2O, NiO, ZnO, etc.) or by renewing kilns; modifying cement chemistry with supplementary materials to reduce clinker consumption or capture CO2; and, recently, using graphene to improve the quality of cement and concrete.

“By 2050, global concrete consumption is expected to increase by 12% to 23% from 25 billion per year.”

According to the National Cement Chamber (CANACEM), most projects registered in Latin America are working on replacing fossil fuels with alternative fuels; Mexico is the only country registering higher production of blended cements to reduce clinker content.

Graphene is a nanomaterial consisting of atomic carbon sheets separated from graphite, with mechanical, electrical, thermal, and barrier properties superior to other carbon-based materials, allowing it to venture into countless applications and industries, including construction. According to estimates by Graphene Flagship, the use of graphene in construction is expected to reduce CO2 emissions by 30%.

“The production of 1 kg of graphene produces 0.17 kg of CO2, compared to 0.86 kg of CO2 for Portland cement, reinforcing the nanomaterial’s environmental advantages.”

Since the isolation of graphene in 2004 and the subsequent Nobel Prize in Physics 2010 awarded to its discoverers, an international race began to study, understand, and obtain the nanomaterial in sufficient quantities for large-scale applications at an affordable cost. In the construction sector, it was not until 2018 that research and investments manifested their first results in various parts of the world, such as:

2018: Graphenemex® launched Nanocreto®, the world’s first graphene oxide concrete additive (Mexico).

2019: Graphenenano developed Smart additives, graphene additives for concrete (Spain).

2019: GrapheneCA presented its OG concrete admix product line for the concrete industry (USA).

2021: Scientists at the University of Manchester developed the Concretene concrete additive (UK).

2022: Energeia Fusion-Graphenemex® launched the Graphenergy construction line, an improved version of Nanocreto® (Mexico).

2022: Versarien presented Cementene™, the world’s first 3D-printed construction with a graphene-reinforced mix (UK).

Basquiroto de Souza and collaborators, in their article “Graphene opens pathways to a carbon-neutral cement industry” published in 2022 in Science Bulletin, summarized the opportunities that graphene has for the sustainability of construction materials:

Reduction of Portland cement thanks to significant improvements in compressive strength and elastic modulus of concrete.

Increase the use of by-products or recycled materials in concrete to reduce greenhouse gas emissions by up to 7%, as well as a 2% reduction in energy consumption during the manufacture of graphene oxide reinforced mortar.

Reduction in construction costs due to improved strength or greater incorporation of by-products or waste materials. A cost analysis concluded that while the use of graphene oxide may slightly increase concrete costs, the economy index (compressive strength/cost per m3) of the mixes can increase by up to 40%.

Reduction in maintenance costs. By improving the quality of concrete structures, reductions in CO2 emissions are inferred through a reduction in the amount of construction materials and energy associated with maintenance.

Energy-efficient buildings: graphene’s thermal properties can also be applied to buildings to achieve energy savings by reducing the use of cooling/heating systems.

For Energeia-Graphenemex®, the leading company in Latin America in designing applications with graphene materials, it is a pride to be part of the graphene timeline for sustainable construction.

Authored by: EF/DHS

References

1. Ige, O.E.; Olanrewaju, O.A.; Duffy, K.J.; Collins, O.C. Environmental Impact Analysis of Portland Cement (CEM1) Using the Midpoint Method. Energies 2022, 15, 2708.
2. International Energy Agency, World Business Council for Sustainable Development. Technology roadmap – low-carbon transition in the cement industry. April 2018
3. Felipe Basquiroto de Souza, Xupei Yao, Wenchao Gao, Wenhui Duan, Graphene opens pathways to a carbon-neutral cement industry, Science Bulletin, 2022, 67, 1, 2022, 5
4. Papanikolaou I, Arena N, Al-Tabbaa A. Graphene nanoplatelet reinforced concrete for self-sensing structures– a lifecycle assessment perspective. Journal of Cleaner Production, 2019, 240: 118202
5. Devi S, Khan R. Effect of graphene oxide on mechanical and durability performance of concrete. Journal of Building Engineering, 2020, 27: 101007
6. Doria- Serrano. Química verde: un nuevo enfoque para el cuidado del medio ambiente. Educación química. 2009. UNAM.
7. https://theplanetapp.com/que-son-las-emisiones-de-co2/
8. https://graphene-flagship.eu/materials/news/materials-of-the-future-graphene-and-concrete/#:~:text=Graphene%2Denhanced%20concrete%20is%202.5,CO2%20emissions%20by%2030%25.
9. https://www.versarien.com/files/5716/3050/8952/White_Paper_-_Graphene_for_the_construction_sector_-_final_version.pdf

Graphene Oxide Versatile Applications:

From Sensing Technologies to Environmental Solutions

Graphene and its derivatives such as graphene oxide (GO) and reduced graphene oxide (rGO) are two-dimensional, sheet-like carbon nanomaterials with a wide range of opportunities for numerous applications due to their thinness, transparency, conductivity, flexibility, chemical stability, impermeability, and mechanical strength. In the case of GO and rGO, in addition to their large surface area with hydrophilic and hydrophobic regions inherent to graphene, they allow the adsorption of organic aromatic molecules, ions, and polymers through π-π stacking, hydrogen bonding, and electrostatic interactions. These properties make them suitable materials for constructing sensors or biocatalytic and photocatalytic platforms. According to various reports, the surface-to-volume ratio of graphene materials enhances the surface charge of the desired molecules, while their excellent electrical conductivity, especially at room temperature, favors electron transfer to the surface of electrodes for analysis or photocatalysis.

On the other hand, graphene sheets are not perfectly flat; they exhibit undulations formed as a result of the bonding between their carbon atoms or thermal fluctuations, which can ultimately induce magnetic fields and alter their electronic properties for designing sensors, biosensors, or electronic devices in general. Thus, through more than ten years of research and exploration of their remarkable multifunctionality, the study of graphene has transcended to the development of highly sensitive devices for monitoring, for example, the presence of harmful gases, medically relevant molecules, or proteins, and even water decontamination.

Detection Systems

Metamaterials are a type of compound with the ability to produce useful electromagnetic responses for designing sensors or non-destructive detection devices. Generally, these sensors consist of an insulating material and a conductive material, sensitive to the refractive index of the analyte’s upper layer. In the presence of graphene, it has been observed that this interaction (sensor-analyte) is enhanced by changes in resonance intensity, leading to amplitude changes that further favor detection sensitivity.

In a study conducted in 2023 by the School of Electronic and Information Engineering at Zhejiang University of Science and Technology, Hangzhou, China, a sensor was designed comprising a polyimide (PI) film as an insulating layer, an aluminum structure as a conductive layer, and a monolayer of graphene as the detection interface. Simulation results indicated that graphene could modulate the entire electric field and produce an amplitude change that significantly increases detection limits.

In another study conducted at the Laboratory of Nanostructured Materials of the Institute of Physics at UASLP, functionalized graphene oxide with gold nanoparticles was used as a SERS (Surface Enhanced Raman spectroscopy) biodetection platform, an important technique for biological detection due to its high sensitivity, low sample requirements, relatively low cost, and real-time detection. Crystal violet was used as the standard molecule and flavin adenine dinucleotide as the experimental coenzyme for its participation in numerous redox processes of metabolic reactions and biological electron transport. The results showed that graphene oxide hybrids with gold nanoparticles substantially enhance SERS signals compared to individual nanoparticles. Additionally, the results are consistent with other research on identifying significant improvements for molecule stabilization and fluorescence reduction during measurements, which is often a major drawback of such techniques, supporting its potential as a diagnostic or monitoring tool.

Toxic Gas Removal

Advances in nanoengineering allow graphene and GO sheets to be manipulated for the detection and separation of certain gases. According to the results of a study conducted by the Department of Energy Engineering at Hanyang University, Seoul, Korea, selective diffusion can be achieved by controlling the gas flow channels and pores through different stacking methods, demonstrating that GO’s functional groups provide a unique adsorption behavior towards CO2.

CO2 Conversion

The photocatalytic properties of GO can also be harnessed for converting CO2 into hydrocarbons such as methanol for solar energy capture and CO2 reduction. In 2018, at the Advanced Technology Laboratory for Materials Synthesis and Processing, Wuhan University of Technology, China, silver chromate (Ag2CrO4) nanoparticles were used as a photosensitizer and GO as a co-catalyst for the photocatalytic reduction of CO2 into methanol and methane. The study concluded that this synergy between nanoparticles could enhance conversion activity up to 2.3 times under solar irradiation due to better light absorption, increased CO2 adsorption, and improved charge separation efficiency.

Water Decontamination

Water technologies have various areas of opportunity, particularly in improving filtration or membrane systems. In this regard, it has been found that using hybrid graphene nanostructures, for example, with ruthenium or magnetite, can allow the removal of microorganisms and organic matter present in water. However, research continues to advance to perfect graphene-based methodologies for the removal and reduction of metal ions such as zinc, copper, lead, cadmium, cobalt, among others.

At Energeia-Graphenemex®, we recognize and admire the advancements that research centers have achieved in various areas of knowledge, starting from basic science to applied science results. We firmly believe that in the short or medium term, these technologies will materialize into real products that are useful to society and the environment.

Redaction: EF/ DHS   

References

1. A. Fasolino, J.H. Los, M.I. Katsnelson, Intrinsic ripples in graphene, Nat. Mater. 6 (2007) 858;
2. W. Bao, F. Miao, Z. Chen, H. Zhang, W. Jang, C. Dames, C.N. Lau, Controlled ripple texturing of suspended graphene and ultrathin graphite membranes, Nat. Nanotechnol. 4 (2009) 562; 3. G. Yildiz, M. Bolton-Warberg and F. Awaja. Graphene and graphene oxide for bio-sensing: General properties and the effects of graphene ripples. Acta Biomaterialia 131 (2021) 62;
3. Lang, T.; Xiao, M.; Cen,W. Graphene-Based Metamaterial Sensor for Pesticide Trace Detection. Biosensors 2023, 13, 560;
4. D. Hernández- Sánchez, E. G. Villabona Leal, I. Saucedo-Orozco, V. Bracamonte, E. Pérez, C. Bittencourt and M. Quintana, Phys. Chem. Chem. Phys., 2017;
5. Kim, H.W.; Yoon, H.W.; Yoon, S.-M.; Yoo, B.M.; Ahn, B.K.; Cho, Y.H.; Shin, H.J.; Yang, H.; Paik, U.; Kwon, S. Selective gas transport through few-layered graphene and graphene oxide membranes. Science 2013, 342, 91;
6. Kim, D.; Kim, D.W.; Lim, H.-K.; Jeon, J.; Kim, H.; Jung, H.-T.; Lee, H. Intercalation of gas molecules in graphene oxide interlayer: The role of water. J. Phys. Chem. C 2014, 118, 11142;
7. Xu, D.; Cheng, B.; Wang, W.; Jiang, C.; Yu, J. Ag2CrO4/g-C3N4/graphene oxide ternary nanocomposite Z-scheme photocatalyst with enhanced CO2 reduction activity. Appl. Catal. B Environ. 2018, 231, 368;
8. Jiˇríˇcková, A.; Jankovský, O.; Sofer, Z.; Sedmidubský, D. Synthesis and Applications of Graphene Oxide. Materials 2022, 15, 920;
9. M. Quintana, E. Vazquez & M. Prato, “Organic Functionalization of Graphene in Dispersions”, Acc. Chem. Res., vol. 46, n.o 1, pp. 138-148, 2013. DOI: 10.1021/ar300138e;
10. Roberto Urcuyo1,2,3, Diego González-Flores1,3, Karla Cordero-Solano, Rev. Colomb. Quim., vol. 50, no. 1, pp. 51-85, 2021;
11. B. Xue, M. Qin, J. Wu et al., “Electroresponsive Supramolecular Graphene Oxide Hydrogels for Active Bacteria Adsorption and Removal”, ACS Appl. Mater. Interfaces, 8, 24, 15120;
12. C. Wang, C. Feng, Y. Gao, X. Ma, Q. Wu & Z. Wang, “Preparation of a graphene-based magnetic nanocomposite for the removal of an organic dye from aqueous solution”, Chem. Eng. J.,173, 1, 92.