Modified biochar as a green adsorbent for removal of hexavalent chromium from various environmental matrices: Mechanisms, methods, and prospects

Temperature dependent fabrication of various rod and rhombohedral-shaped mesoporous Co3O4 crystals and their capability towards elimination of toxic Cr(vi) ions from the aquatic environment

“…Consequently, we have tested some single and multi-charged ions such as Na + , Ca 2+ , Al 3+ , NO 3 − , Cl − , HCO 3 − , SO 4 2− and PO 4 3− to verify their interaction with Co 3 O 4 (400 °C) in the Cr( vi ) reduction process. 93 We see that at a low concentration (Fig. 11b), the ions do not have any effect but in a high concentration medium, the cations can somewhat enhance the Cr( vi ) adsorption by Co 3 O 4 as they can be attached to the adsorbent surface to attract more Cr( vi ) ions to get adsorbed on the active sites, which eventually slightly increases the removal rate (from 92.9 to the highest value 97.5% for Al 3+ ).…”

“…At acidic pH, due to the presence of H + ions, the Cr(VI) ions convert to Cr 2 O 7 2À and HCrO 4 À ions and subsequently fewer toxic Cr(VI) ions are degraded via the chemisorption process on the sorbent surface bed. 93,94 However, at basic pH, the dominant CrO 4 2À ions (yellow color) are electrostatically repelled by the deprotonated surface of the adsorbent leading to a decrease in the Cr(VI) ion adsorption and reduction process. A very recent report 95 has shown that the maximum degradation occurs at the acidic pH.…”

“…in the Cr(VI) reduction process. 93 We see that at a low concentration (Fig. 11b), the ions do not have any effect but in a high concentration medium, the cations can somewhat enhance the Cr(VI) adsorption by Co 3 O 4 as they can be attached to the adsorbent surface to attract more Cr(VI) ions to get adsorbed on the active sites, which eventually slightly increases the removal rate (from 92.9 to the highest value 97.5% for Al 3+ ).…”

Influences of Biochar on Bioremediation/Phytoremediation Potential of Metal-Contaminated Soils

“…Plant yield increases with biochar supplementation ( Ambika et al, 2022 ) are connected to water and nutrient retainment, enhanced biological activities, and neutralized soil pH. Hence, biochar has the efficiency to be used as an amendment to reduce metal bioaccumulation in plants.…”

Simultaneous removal of four aflatoxins using magnetic nanobentonite as a green and fast sorbent; Kinetic,termodynamic and isotherm investigation

“…Still, the most significant limitation of most of these sorbents is their low sorption capacity, which limits their use (Li et al 2016). Therefore, modifying the sorbent surface with nanomaterials, changing the sorbent structure with chemical treatment, or functionalizing their surface with proper functional groups enhances the sorption capacity of contaminants by creating appropriate physical and chemical interactions between the modified green sorbent and the pollutants (Ambika et al 2022, Ibrahim et al 2019.…”