Two-Step Hydrothermal Reaction Enhances Removal of Cr(VI) from Wastewater Using Nitrogen-Doped Starch-Based Hydrothermal Carbon

Extracting Cr(VI), a heavy metal known for its carcinogenic properties, from water poses a significant challenge. This research involved synthesizing nitrogen-infused starch-derived hydrothermal carbon (NS-HCS) from starch using a dual-phase hydrothermal method, aimed at removing Cr(VI) from industrial wastewater. N-doping increased the N content from 0.27% to 3.64%, providing active sites for enhanced Cr(VI) adsorption and reduction. Experimental data demonstrated 149.21 mg/g contaminant uptake capacity with 49.74% removal efficiency under specified conditions. Analysis of the kinetic and isotherm models revealed that the adsorption mechanism was characterized primarily by multilayer adsorption. Furthermore, after six cycles of use, NS-HCS demonstrated good reusability, with its Cr(VI) adsorption capacity remaining at approximately 79.05%. Additionally, NS-HCS exhibited strong resistance to interference in complex aqueous environments. This study provides new insights into the use of green and sustainable adsorbents, offering an economical and efficient solution for treating Cr(VI)-contaminated wastewater.