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In a significant step towards mass commercialization, Italian company Directa Plus recently received a European patent for Grafysorber, a graphene-based water filtration system specifically designed to remove toxic hydrocarbons and sludge.
Grafysorber uses "two-dimensional" graphene in a 3D configuration. The technology features atomically thin graphene sheets as a sponge to soak up hydrocarbons from polluted water. Ready-to-use Grafysorber has been made available as a floatation barrier, a boom and floatable adsorbent pillows.
According to Directa Plus, the system's distinctive oil adsorption ability has been proven through considerable evaluations and trials that were conducted in Romania, Italy, and Nigeria. These trials showed that Grafysorber is at least five times more efficient than similar water filtration technologies currently in use. The system can adsorb at least 100 times its weight in pollutants. Oil adsorbed by Grafysorber can also be readily recovered for recycling or safe disposal.
Directa Plus said the patent addresses effluent waters, wastewater from oil refinery operations, and any type of wastewater that includes significant quantities of hydrocarbons. These types of wastewater can be challenging and costly to treat, often requiring complicated multi-step treatment systems. Using Grafysorber, on the other hand, involves a fast one-step process. A demonstration version of the method involves placing a flotation device in polluted water and skimming toxins off the surface.
Directa Plus provides Grafysorber to multiple European oil and gas businesses through a subsidiary called Setcar. The system offers a convenient, fast-acting remedy for oil spill situations.
Field trials have revealed Grafysorber works well on high and low total petroleum hydrocarbons (TPH) concentrations, with concentrations swiftly lowered by the system to an acceptable value. Moreover, only a small quantity of Grafysorber is necessary to accomplish the desired outcome. The device is reusable up to five times and is made entirely of carbon, an eco-friendly fabrication material. It is possible to use Grafysorber alongside other water purification systems.
Oil clean-up performed by Grafysorber®
Video Credit: Directa Plus/YouTube.com
Developing an Industrial Grafysorber Process
In 2018, Directa Plus announced a partnership with Sartec Srl to develop an industrial pilot plant system based on Grafysorber technology. According to an announcement, the agreement was to create an industrial-scale process and system that could effectively treat high volumes of wastewater from oil and gas operations. As with Grafysorber, any hydrocarbons extracted could completely and easily be recovered. The agreement also included developing a way to recycle the Grafysorber itself.
The purpose of the agreement is to develop a system able to treat as much as 500 cubic meters daily of wastewater. Target customers for this technology include large oil extraction businesses and refineries. The companies are also looking to market the process to organizations dedicated to ecological remediation of oil spills.
Modifying Graphene for Water Remediation
Phenyl compounds, pesticide sprays and chemical dyes can all damage living things and disrupt natural cycles. For instance, researchers have established that approximately 10% of toxic commercial dyes are discharged into wastewater. The extraction of these dyes is necessary for supporting public health and minimizing environmental damage.
To tackle these types of wastewaters, many materials scientists have been concentrating on advancements in graphene modification that produce adsorbents capable of removing organic wastes from water. More specifically, researchers have been using atomic doping and defect creation to develop adsorbents.
How are graphene-based water filters being used to produce clean drinking water from polluted water?
Structural modifications that form vacancies in the graphene sheet or doping with metal atoms can modify essential electronic qualities and reactivity. The graphene sheet may also be altered by affixing an oxide, peroxide or other functional group to produce hydrophilic graphene oxide. The addition of these critical functional groups also makes graphene oxide disperse readily in organic wastes. Graphene oxide is an electrical insulator due to the disruption of its signature bonding network.
There are six possible types of molecular interactions that make adsorption possible using graphene: electrostatic bonding, hydrogen bonding, hydrophobic effect, Lewis acid-base interactions, p-bonding and van der Waals forces. Moreover, the defect locations and functional groups of graphene are locations for nucleation and nanoparticle growth. To create adsorbents, scientists have looked to restore the original hexagonal lattice and electrical conductivity of graphene by reducing graphene oxide. To do this, a large number of oxygen groups must be taken out.
Essential exterior qualities that have an impact on graphene adsorption are surface area and distribution of pore sizes. Pure graphene has an extremely high surface area but zero porosity.
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An innovative development for graphene adsorption is the introduction of porosity through the merging of porous additives, such as chitosan and silica. A different approach to attaining necessary adsorption performance is through the introduction of various functional groups, which play a crucial role in creating bonds with adsorbates.
Both graphene oxide and reduced graphene oxide have several oxygen-containing functionalities that can create bonds with adsorbates. Production of functionalized graphene, with a large surface area and high porosity, is essential to the use of graphene in ecological remediation.
Graphene-based adsorbents have proven very promising for the elimination of various organic wastes. These materials display superior adsorption capabilities compared with graphene oxide or reduced graphene oxide due to abundant adsorption locations such as certain functional groups and p electrons and nanoparticles.
Graphene acts as scaffolding that stops the ions from leaking into the solution. The intricate qualities of graphene-based nanocomposites have inspired scientists to establish novel fabrication methods that are more suited to synthesizing adsorbents for water remediation.
It is likely that ecological uses of graphene-based adsorbents will not be limited to water remediation. According to experts, graphene also shows significant promise for air and soil remediation. The prime adsorption capacity enables the extraction and division of contaminants from water, air, and soil without unwanted side effects.
References and Further Reading
Muirhead, C. (2020) Directa Plus secures EU patent for Grafysorber water treatment technology. [Online] Proactive Investors. Available at: https://www.proactiveinvestors.co.uk/companies/news/918148/directa-plus-secures-eu-patent-for-grafysorber-water-treatment-technology-918148.html (Accessed on 2 June 2020).
Ashcroft, J. (2020) Directa Plus lands innovation award for graphene-based water decontamination technology. [Online] Proactive Investors. Available at: https://www.proactiveinvestors.co.uk/companies/news/919799/directa-plus-lands-innovation-award-for-graphene-based-water-decontamination-technology-919799.html (Accessed on 2 June 2020).
Peleg, R. (2018) Directa Plus and Sartec to commercialize graphene-based solution for oil & gas industry. [Online] Graphene Info. Available at: https://www.graphene-info.com/directa-plus-and-sartec-commercialize-graphene-based-solution-oil-gas-industry (Accessed on 2 June 2020).
Directa Plus (2018) Directa Plus and Sartec to commercialise Grafysorber®-based solution for oil & gas industry. [Online] Available at: https://89099cef-be50-4f0c-bbfb-54ae33720ac5.filesusr.com/ugd/1f30fc_cfc8360d51fc492aa3858a9fae597094.pdf (Accessed on 2 June 2020).
Mandeep, Gulati, A., Kakkar, R. (2020) Graphene-based adsorbents for water remediation by removal of organic pollutants: Theoretical and experimental insights. Chemical Engineering Research and Design. Available at: https://doi.org/10.1016/j.cherd.2019.10.013