Chromium Removal by the Use of Biomass-Derived Activated Carbon and Biosorbents (Low-Cost Adsorbents)

Cr (VI), a heavy metal found in aquatic environments, causes cancer, lung tumors, and allergies, among other problems in people. In order to obtain the maximum adsorption capacity for Cr (VI) adsorption, this review evaluates the use of various adsorbents, which include biosorbents and activated carbon made from biomass, while keeping an eye on the operating parameters (beginning pH, adsorbent dosage, temperature, Cr (VI) concentration, and contact time). The study concludes that the highest possible capacity for adsorption of Cr (VI) adsorption can be achieved through the use of activated carbons and biosorbents. The pH of the solution has a major impact on Cr (VI) adsorption; in an alkaline pH environment, Cr (VI) adsorbed little to none at all, but in an acidic pH environment, it adsorbed heavily. Using kinetic, isotherm, and thermodynamic mechanisms, an analysis has been conducted on the Cr (VI) adsorption data. To fit adsorption data, the Langmuir equation and a pseudo-second-order (PS2) kinetic model are commonly employed. Generally, Cr (VI) is adsorbed by the outer-sphere Cr (VI) compound at pH values over 6 and by the internal zone Cr (VI) compound at pH levels under 6. This work is important since it provides several insights into the Cr (VI) adsorption process.