A Novel Graphite-Based Sorbent for Oil Spill Cleanup

Abstract

The performance of an innovative material based on expanded graphite, Grafysorber® G+ (Directa Plus), has been tested through laboratory, tank, and confinement tests for oil removal in case of an oil spill and water treatment. In addition to the ability to retain oil, the possibility of reusing this material after regeneration via squeezing was also evaluated. As a comparison, the same experimental tests were conducted using polypropylene flakes (PP), the material currently most used to deal with spill accidents. Oils with different chemical and physical properties were used, namely kerosene, diesel, and crude oil. From the laboratory tests, the capacity of Grafysorber® G+ to retain oil was found to be directly proportional to the viscosity of the latter, with adsorption values ranging from 76.8 g/g for diesel to 50.8 g/g for kerosene, confirming the potential of the innovative material compared to the PP. Cyclical use tests have confirmed certain reusability of the material, even if its adsorbent capacity decreases significantly after the first cycle and continues to decrease in subsequent cycles, but a less marked manner. Finally, some considerations based on the adsorption capacities were found to suggest that the adoption of the new material is also economically preferable, resulting in savings of 20 to 40% per kg of hydrocarbon treated.

Effect of Process Parameters on the Graphite Expansion Produced by a Green Modification of the Hummers Method

“…EV is an important parameter for adsorption efficiency because the material capacity increases as this parameter rises. There was mentioned that increasing EV values constitute a clear strategy to improve material performance further [ 1 ]. It is commented that oil adsorption capacity depends on not only the surface area but also the pore structure of the material since there is a strong dependence on EV and worm lengths [ 51 ].…”

“…To separate oil from the saturated EG, some process has been described but have many disadvantages: using filtration, the recovered amounts of oils decrease rather markedly with increasing recycling times due to the oil retention in the pores or on the surface of EG [ 53 ]. The manual squeezing of EG contained in pillows is a tedious and not-scalable process; it generates a loss of particles from the pillow and a decrease in the absorbent capacities after each cycle due to changes in the structural and morphology of the particles [ 1 , 27 ]. Oil recovery with compression was about 30% and decreased with increased regeneration cycles [ 2 ].…”

“…An oil spill is an accidental or deliberate release of solid or liquid hydrocarbons into the environment [ 1 ]. Although hydrocarbons are present in various types and forms, they are generally problematic to remove, causing catastrophic effects on ecosystems if effective treatment is not correctly applied.…”

“…The classical method for the EG preparation using chemical reactions is cheap and easily scalable, but it requires the mandatory use of highly concentrated mineral acids with strong oxidizing agents for the graphite intercalation process [ 11 ]; these chemicals and their corresponding reaction remnants can cause adverse environmental effects if they are not disposed of properly. An ideal adsorbent must not only show high efficiency and mechanical strength for practical use, but it also needs an adequate balance with some features such as low cost and high biodegradability; because it is important to preserve the adsorption performance under requirements such as sustainability and green remediation, where the main idea is to replace the use of toxic reagents with lower impact ones [ 1 ]. This is in good agreement with a concept developed in the business and regulatory communities as a natural evolution of pollution prevention initiatives, called green chemistry.…”

Screening of Plants and Indigenous Bacteria to Improve Arsenic Phytoextraction

“…The remediation of contaminated sites is therefore of primary importance, as evidenced by the numerous physicochemical and biological solutions developed for the recovery of contaminated water [5][6][7][8] and soils [9][10][11][12] in recent years. However, an often-overlooked aspect is that remediation activities also have an environmental impact as they frequently rely on chemical products or processes, with consequent consumption of raw materials and energy.…”