Pb2+ removal performance by cotton-based and magnetic modified cotton-based biochar prepared from agricultural waste biomass.

This study aimed to investigate the Pb²⁺ removal performance of cotton-based biochar (CB) and magnetic modified cotton-based biochar (MCB). The scanning electron microscopy revealed that MCB exhibiting a porous honeycomb structure with a specific surface area of 613.69 m²/g which bigger than that of CB (356.68 m²/g). The Fourier transform infrared spectrum analysis indicated the presence of metal oxides and hydroxides in MCB and the functional groups of O-H, C=O, and C=C in both MCB and CB. The signal of Fe3O4 and Fe3C was observed in X-ray diffraction analysis of MCB, which indicated the success of magnetic modification of MCB. The maximum monolayer adsorption capacities (Qm) of MCB and CB on Pb²⁺ were 208.33 and 156.25 mg/g, respectively. The adsorption kinetics of MCB and CB were both best fitted with the pseudo-second-order model (R² > 0.99), and the adsorption isotherms of the two biochar were well-described by the Langmuir adsorption model (R² > 0.99). The results of this study revealed the significant physicochemical difference of two biochar and indicated that magnetic modification can enhance the Pb²⁺ adsorption capacity of biochar, suggesting that MCB is a potential adsorbent for wastewater treatment. [ABSTRACT FROM AUTHOR]