GRAFTA™: A Total Solution for Hydrocarbon removal from Water

The challenges of Hydrocarbon removal

Various hydrocarbon compounds ranging from simple petroleum hydrocarbons (PHCs) to more molecularly complex compounds such as chlorinated solvents and polycyclic aromatic hydrocarbons (PAHs) find their way into water resources from a variety of sources.

Petroleum hydrocarbons and BTEX (benzene, toluene, ethylbenzene and xylene) can enter surface water and groundwater resources through leakage or spillage from gas stations, oil and gas operations, fuel storage tanks and other sources.

Volatile organic compounds (VOCs) are compounds that have a high vapor pressure and relatively low water solubility. Many VOCs are human-made chemicals that are used and produced in the manufacture of paints, pharmaceuticals, and refrigerants. VOCs typically are industrial solvents, such as tetrachloroethylene (also known as perchloroethylene or PCE), trichloroethylene (TCE); fuel oxygenates, such as methyl tert-butyl ether (MTBE); or by-products produced by chlorination in water treatment, such as chloroform. VOCs are often components of petroleum fuels, hydraulic fluids, paint thinners, and dry-cleaning agents.

Polycyclic aromatic hydrocarbons (PAHs) are a group of over 100 chemicals formed during the incomplete burning of coal, oil, gas, wood, garbage, and other organic substances. Examples of PAHs, that are also regulated under the Canadian Environmental Protection Act are; acenaphthene, anthracene, benzo[a]anthracene, benzo[a]pyrene (B[a]P), fluoranthene, fluorene, naphthalene, phenanthrene, and pyrene. Polycyclic aromatic hydrocarbons are a major component of creosote.

GRAFTA™, an innovative graphene-based nanotechnology designed for the efficient removal of various contaminants from industrial and mining wastewater, has shown outstanding performance in removing hydrocarbons from industrial wastewaters.

While GRAFTA™1.0 (G1) has shown remarkable promise in removing a wide range of organic compounds from contaminated waters and wastewaters, Grafta Nanotech Inc. has introduced a total solution including a new product; GRAFTA-F which in combination with G1 provides a facile adsorptive removal of wide range of hydrocarbons from contaminated waters and wastewater.

GRAFTA-F has shown to be capable of both bulk absorption of free phase and adsorption of the dissolved phase hydrocarbons, enhancing the performance and longevity of G1.

This data sheet provides a technical overview of GRAFTA™'s mechanisms, performance metrics, and application requirements for targeting hydrocarbons.

The GRAFTA™ Product Line

GRAFTA™ comprises micro-scale inert particles embedded with numerous layers of graphene and graphene oxide nanosheets. The product is available in two formulations:

GRAFTA™ 1.0 (G1)

Designed for the adsorption of heavy metals and organic compounds. The core graphene based solution targeting metals, petroleum hydrocarbons, PAHs, BTEX, wide range of VOCs and Semi-VOCs including but not limited to chlorinated solvents (e.g. PCE, TCE, etc.), PCBs and a range of inorganics such as ammonia and phosphate.

GRAFTA™ 2.0 (G2)

GRAFTA™2.0 is engineered to add chemical reduction capability targeting reductive removal of metals particularly in higher oxidation states to target contaminants like selenium present as selenate followed by adsorption within the same matrix.

GRAFTA™-F

A polymer-based hydrocarbon absorption product, capable of removing both free phase and dissolved organic compounds from aqueous solutions

GRAFTA™ particles

The unique structure of GRAFTA™ provides a substantial surface area for adsorption, ensuring high contaminant removal efficiency.

Hydrocarbon Removal Process using GRAFTA™

The total solution provided by Grafta Nanotech Inc. Includes a two-stage adsorption process using the GRAFTA™-F upfront of a G1 filter to remove free phase hydrocarbons (if any) as well as partial removal of dissolved hydrocarbons, and leave the dissolved phase hydrocarbons (and other constituents such as heavy metals) for G1 to be removed through adsorption.

The overall mechanism of hydrocarbon removal by both products are based on strong affinity to hydrocarbons and are achieved mainly through adsorption.

Hydrocarbon Removal Performance

Several bench scale tests, using contaminated water samples, have been conducted to evaluate the performance of the GRAFTA™ Total Hydrocarbon Solution (G-THS). In a most recent example, water collected from a cooling tower application that was contaminated with PAHs as well as Petroleum Hydrocarbons, was subject to a performance test using the G-THS.

As shown in the following chart, the G-THS reduced the concentration of all the PAHs to either nondetectable concentrations or below the regulatory limits.

GRAFTA™ removal of PAHs

Influencing Factors

G-THS performance in removal of a wide range of hydrocarbons is not hindered by environmental factors such as temperature or some of the typical chemical composition of the water subject to treatment.

There is no need to adjust the pH of water prior and after removal by G-THS. In most cases, it is expected to have other ions and metals be present in waters subject to hydrocarbon removal.

Our comprehensive testing has showed that other metals are also removed simultaneously.

Application Requirements

Large-scale application of G-THS for total hydrocarbon removal is indeed simple and can be achieved by using any type of above ground vessel (tanks of various sizes and shapes, and made of either polyethylene or steel), that can house G1 and accommodate a preferably upflow hydraulic regime provided by minimal pumping requirement where gravity feed is not viable.

The GRAFTA™-F can also be packed in relatively smaller quantities (due to high adsorption capacity) in bag filters and placed prior to the G1 filter.

Typical retention time (Empty Bed Contact Time (EBCT)) of less than 10 minutes would typically result in over 99% removal of hydrocarbons.

A standard GRAFTA™ system

End-of-Life Management

GRAFTA™ exhibits minimal leaching of adsorbed contaminants, ensuring environmental safety. Toxicity Characteristic Leaching Procedure (TCLP) tests have confirmed that leachate concentrations are below regulatory limits, facilitating safe disposal or repurposing of spent media.

Further Case Studies

Please visit www.grafta.tech/case-studies for further information on GRAFTA™ being applied to a range of real world waters with excellent results.

GRAFTA™: A Total Hydrocarbon Removal Solution

GRAFTA™ (G-THS) offers an effective solution for the removal of PHCs and BTEX from contaminated waters and wastewaters, achieving non-detectable effluent concentrations with relatively short retention times.

For further information or inquiries, please contact GRAFTA Nanotech Inc.