A Comparative Analysis of Zn<sup>2+</sup> Adsorption from Simulated Mining Wastewater Using Unmodified and NaClO-Modified Sugarcane Bagasse-Derived Biochar

This study evaluated the adsorption of Zn 2+ from simulated mining wastewater using unmodified sugarcane bagasse-derived biochar (U-SCBB) and NaClO-modified sugarcane bagasse-derived biochar (SH-SCBB). The effectiveness of NaClO modification in enhancing the biochar's adsorption capacity was a key focus of this research. Results indicated that both U-SCBB and SH-SCBB exhibited significant Zn 2+ adsorption capabilities, with SH-SCBB showing superior performance. Specifically, SH-SCBB achieved the highest Zn 2+ removal efficiency at pH 5 and adsorbent dosage of 0.9 g. Adsorption behavior and maximum Zn 2+ removal were modeled using various isotherms, including Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Flory-Huggins (F-H), and Temkin. It was determined that the SH-SCBB was best described by the D-R isotherm with a coefficient of determination or R 2 equivalent to 0.96. Kinetic data were analyzed with Pseudo-First Order (PFO), Pseudo-Second Order (PSO), Elovich, and Intra-Particle Diffusion (IPD) models, and it was found to pattern out a PSO model with an R 2 of 0.99, suggesting a physisorption process with an equilibrium time of 75 minutes. Optimal adsorption considering statistical significance was at pH 5 with 0.7 g of SH-SCBB, underscoring its potential as a cost-effective and environmentally sustainable adsorbent for Zn 2+ removal in mining wastewater treatment.