Non-wood-based biochars as promising and eco-friendly adsorbents for chromium hexavalent Cr (VI) removal from aquatic systems: state-of-the-art, limitations, and potential future directions

Abstract

Chromium exists from both natural geological processes and human actions, and it has a substantial impact on both human health and natural ecosystems. This study addresses the major challenges in using biochar as an environmentally friendly, sustainable, and economical sorbent for removing chromium hexavalent throughout the remediation process. The results exhibited that biochar produced from non-woody feedstocks pyrolyzed at (300°C −700°C) exhibited a significantly large amount of various functional groups, higher pH (7 to 11.10) and CEC (27 to 21.70 cmol kg−1), greater surface area (2–300 m2g−1), higher O/C and H/C ratios with increasing carbonization temperature, and higher adsorption capacities (1.63 to 435 mg g) and superior performance for chromium hexavalent removal compared to biochars produced from woody-biomass. The use of equilibrium isotherm, thermodynamic, and kinetic models aids in comprehending the interactions between chromium hexavalent and biochar, as well as their adsorption processes.