6,7 Cr( VI) is toxic even at parts per billion levels.
1–5 Chromium( VI) compounds, like hydrogen chromate (HCrO 4 −), chromate (CrO 4 2−) and dichromate (Cr 2O 7 2−), owe their toxicity to the high solubility and diffusivity which permit them to cross the biological membrane tissues easily. Introduction Over the past decades, the preparation and application of various adsorbent materials for the sequestration of toxic hexavalent chromium (Cr( VI)) from environmental samples have received vast attention from researchers across the world. This review focused on the recent advances, insights, and project future directions for these adsorbents as well as compare and contrast the performances achieved by the mentioned adsorbents and their variants. Initially, adsorbents were used singly in their natural form, but recent literature shows that more composite materials are generated and applied. Many adsorbents, including synthetic polymers, activated carbons, biomass, graphene oxide, and nanoparticles as well as bioremediation, have been successfully applied in Cr( VI) remediation.
Mitigation of chromium using adsorption methods has been achieved by exploiting the physical, chemical, and biological properties of Cr( VI) due to its dissolution tendencies in aqueous solutions. Amongst the removal techniques reported in the literature, adsorption methods are viewed as superior to other methods because they use less chemicals consequently, they are less toxic and easy to handle. While Cr( III) is a micronutrient, Cr( VI) is a known carcinogen, and that warrants removal from environmental samples. Chromium exists mainly in two forms in environmental matrices, namely, the hexavalent (Cr( VI)) and trivalent (Cr( III)) chromium.
0 kommentar(er)
