Waste‐Derived Crayfish‐Shell Biochar for Norfloxacin Removal: Mineral‐Driven Adsorption Mechanisms

Abstract

ABSTRACT Crayfish–shell waste (CSW) is an abundant aquaculture by–product rich in biogenic minerals; however, the contribution of these inherited mineral phases to antibiotic adsorption remains poorly understood. Herein, pyrolysis–derived crayfish–shell biochar (CSB) was prepared without chemical activation or external modification and evaluated for norfloxacin (NOR) removal. CSB showed a high solid yield of 62.75% and a Langmuir maximum adsorption capacity of 129.42 ± 7.79 mg g −1 for NOR. Structural characterization revealed a hierarchically porous honeycomb‐like matrix with interconnected micro–mesopores, which facilitated pore–filling adsorption. Combined characterization by XRD, SEM–EDS, XPS, and FTIR analyses suggested that NOR adsorption was governed by pore filling, hydrogen bonding, and mineral–associated surface interactions, while acid demineralization experiments and DFT calculations further confirmed that NOR exhibited stronger adsorption on inherited Ca/Mg–containing mineral surfaces than on carbon surfaces. After five adsorption–desorption cycles, CSB retained 85.1% of its initial NOR adsorption capacity, accompanied by negligible changes in its morphology, mineral phases, and surface functional groups, indicating good structural stability. This study demonstrated a sustainable approach for converting CSW into functional biochar while highlighting the potential role of inherited mineral phases in enhancing antibiotic adsorption, which provides a novel strategy for coupling aquaculture waste valorization with antibiotic pollution control.