GRAFTA Nanotech
Frequently Asked Questions
Q.
What is graphene?
A.
Graphene is a single layer of carbon atoms arranged in a two-dimensional honeycomb lattice structure. It is the basic building block of other carbon allotropes, such as graphite, carbon nanotubes, and fullerenes. Graphene is unique in that it has extraordinary physical and chemical properties, making it one of the most studied and promising materials in the field of materials science and nanotechnology.
Key characteristics and properties of graphene include:
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Two-Dimensional Structure: Graphene is just one atom thick, which gives it its two-dimensional nature. It forms a flat, hexagonal lattice resembling a honeycomb.
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Exceptional Strength: Graphene is incredibly strong and has one of the highest tensile strengths of any known material. It can withstand significant mechanical forces without breaking.
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High Electrical Conductivity: Graphene is an excellent conductor of electricity due to its high electron mobility. Electrons can move through graphene with very little resistance, making it a potential material for advanced electronics.
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Exceptional Thermal Conductivity: Graphene also exhibits extremely high thermal conductivity, which means it can efficiently dissipate heat. This property has implications for applications in thermal management.
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Van der Waals Forces: Graphene exhibits strong van der Waals forces, which are attractive forces between atoms and molecules. These forces can lead to the adsorption of various substances, particularly non-polar molecules.
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Transparency: Graphene is transparent, allowing visible light to pass through it. This property makes it potentially useful in transparent electronics, such as touchscreens and flexible displays.
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Impermeability: Despite being just one atom thick, graphene is impermeable to most gases and liquids, including helium and even water when in its purest form.
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Lightweight: Graphene is very lightweight, adding minimal weight to composite materials while providing significant strength.
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Chemical Reactivity: Graphene's surface can be chemically modified to introduce specific properties or enhance its performance in various applications.
Graphene has numerous potential applications, including in electronics, sensors, energy storage devices (like batteries and supercapacitors), composite materials, medical devices, and even water purification. However, commercializing graphene-based products on a large scale has proven challenging due to the difficulty of producing high-quality graphene sheets and integrating them into practical devices.
Q.
How does GRAFTA work?
A.
GRAFTA™ is comprised of bonded graphene nanosheets, creating a microparticle that utilizes the massive specific surface area of graphene at its nano scale of approximately 2600m2/gram and exceptional adsorption capacity of graphene to create a highly effective and efficient platform for contaminant removal.
The adsorptive capacity of GRAFTA™ is owed to its graphemic structure, where thousands of multilayered graphene and graphene oxide nanosheets are available, firmly grown on an inert base substrate. This provides a very large surface area for adsorption and through a variety of adsorption mechanisms including Van der Waals and covalent adsorption enables GRAFTA™ to remove many of the most difficult to remove industrial contaminants.
Organic contaminants are mainly adsorbed onto the graphene layers while heavy metals are adsorbed on the graphene oxide, both present on GRAFTA™ micro-sized particles. A suitable ratio of carbon to oxygen is maintained through the production process to achieve this unique combination.
For more information on how GRAFTA™ works please view the White Paper.
Q.
What kind of applications GRAFTA be used in?
A.
GRAFTA™ is a versatile solution for water remediation and can be used in a range of ways, including:
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GRAFTA™ can be integrated into existing treatment trains to provide enhanced contaminant removal and water polishing;
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GRAFTA™ can be used as a single treatment solution in an in-line filtration system;
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GRAFTA™ can be applied in-situ through injection into groundwater systems to form permeable reactive barriers (PRBs).
Q.
What contaminants does GRAFTA remove the best?
A.
The key advantage of using GRAFTA™ is that it simultaneously adsorbs both heavy metals, dissolved minerals and tough to remove organic compounds such as chlorinated solvents, petroleum hydrocarbon, polycyclic aromatic hydrocarbons (PAHs), Volatile Organic Compounds (VOCs) such BTEX (benzene, toluene, xylene, ethylbenzene) and more importantly PFAS which is currently under further investigation.
GRAFTA™ removes a range of contaminants that are generally difficult to remove with existing treatment technologies. Selenium is an excellent example with GRAFTA™ being shown to remove to non-detectable levels, with other elements including arsenic, lead, mercury, copper, nitrates and cadmium, which can all be significant contaminants, especially in the mining industry.
For more information on contaminants removed please view the Contaminant Matrix.
Q.
What does a GRAFTA system look like?
A.
GRAFTA™ is a passive technology that smoothly integrates into existing treatment trains.
Systems are designed for the specific nature of the site and contaminant with key factors being the flow rate and retention time to process waters and remove contaminants.
In general, GRAFTA™ line of products can be used either in above-ground (onsite) form (e.g. tanks and vessels) or in in-situ form through injection into groundwater systems to form permeable reactive barriers (PRBs).
In most cases, an up-flow hydraulic regime is preferred for a slight expansion of the GRAFTA™ packing for higher contact surface area.
A typical cross section of a vessel housing GRAFTA™
Q.
Is GRAFTA safe?
A.
GRAFTA™ is essentially a micro-scale particle with nano-scale graphene and graphene oxide layers formed over the surface. As a result, the thermally induced strong chemical bond eliminates the possibility of nano-scale graphene and graphene oxide release into the environment, providing a safe and stable platform for contaminant adsorption.
GRAFTA™ does not require harsh chemicals to break down contaminants, it is non-toxic and non-leaching to the environment.
Q.
Can it be used on contaminanted groundwater?
A.
Yes. GRAFTA™ can be used to remediate contaminated groundwater in situ through injection or placement to create a permeable reactive barrier that removes contaminants as they flow through. This can provide significant benefits for contaminated industrial sites and groundwater systems.
Q.
What sort of infrastructure does GRAFTA require?
A.
A passive technology, GRAFTA™ requires minimal infrastructure to operate, with the key components required including:
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Power to run pumps.
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Modular filtration systems such as tanks
GRAFTA™ systems have a small footprint and can be well-suited to remote and difficult-to-access areas.
Q.
How long does GRAFTA last?
A.
GRAFTA™ has proven to have significant longevity in removing key contaminants of concern and in some cases, breakthrough is not achieved even over 6000 pore volumes of permeation. The lifetime of GRAFTATM is significantly longer than other existing solutions such as Activated Carbon, providing for longer treatment timeframes, however, performance varies from site to site and different contaminants of concern.
Q.
What happens at end of life? How do you dispose of GRAFTA?
A.
Used GRAFTA™ (not necessarily at the end of life) has been tested for leaching contaminants in accordance with Toxicity Characteristics Leaching Procedure (TCLP) and the results have indicated that leaching is minimal and, in all cases, (for metals) below the regulatory limits set in Canada (more specifically Ontario). The two most common ways to dispose of GRAFTA™ are:
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Landfill: Upon verifying the leaching compliance with applicable land disposal regulations (in Canada and elsewhere), the simplest option for end-of-life GRAFTA™ would be disposal in a regular landfill or hazardous landfill based on the standard TCLP results.
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Reuse: Considering the fact that GRAFTA™ has physical and mechanical properties similar to fine sand and the fact the leaching of contaminants is minimal, it can be used in a variety of construction schemes, such as applications in road base or subbase material or low strength concrete, or as landfill intermediate or final cover which might be beneficial as it can act furthermore as part of a biocover system. These uses, however, should be verified on a case-by-case basis and a general rule may not be applied.