Efficient Removal Behavior of Cr (VI) by KOH‐Modified Wood Apple Shell Porous Biochar Adsorbent: Mechanisms and Performance
Xu Zhang, Shufan Bi, Ziheng Yang, Sheikh Tamjidur Rahman, Yiqiang Zhang, Geming WangABSTRACT
Industrial development has intensified water pollution, with hexavalent chromium Cr (VI) posing severe health risks due to its toxicity and carcinogenicity. This study synthesized ultrahigh‐surface‐area porous biochar from waste wood apple shells via sequential carbonization and KOH activation for efficient Cr (VI) removal. Physicochemical characterization revealed that KOH activation transformed the native biomass into a hierarchical micro/mesoporous structure with specific surface area of 1657 m 2 /g, pore volume of 0.671 cm 3 /g, and enriched oxygen‐functional groups. Experiments demonstrated exceptional Cr (VI) uptake (312 mg/g at pH 2.0, 298 K), driven by chemisorption‐dominated mechanisms. Kinetic analysis followed the Elovich model, confirming heterogeneous adsorption, while equilibrium data aligned with the Langmuir model, showing monolayer coverage. XPS analysis confirmed partial reduction of Cr (VI) to Cr (III) (42.25%) through redox reactions and complexation with surface functional groups. This work presents a sustainable strategy for valorizing agricultural waste into high‐performance adsorbents for chromium‐laden wastewater remediation.