Evaluation of optimized conditions for the adsorption of malachite green by SnO2-modified sugarcane bagasse biochar nanocomposites

Abstract

This work deals with the synthesis of SnO₂-modified sugarcane bagasse biochar (SnO₂-SBB) nanocomposites using an impregnation method. XRD, FTIR, SEM, and EDX analyses were used to characterize the produced nanocomposites. Several factors influencing the removal of malachite green from wastewater via the adsorption process were explored to maximize the effectiveness of this process. These factors included the different doses of nanocomposites, pH, temperature, contact time, etc. Studies on batch adsorption were conducted to examine the impact of operational parameters, such as contact time (5 to 30 minutes), adsorbent dosage (5 to 40 mg), pH (2 to 10), and temperature (303, 323, and 353 K), on the percentage of MG dye removal. The adsorption kinetics of MG dye over SnO₂-SBB nanocomposites were evaluated with the aid of the Langmuir adsorption isotherm, which provided a good fit (R² = 0.99) for pseudo-second-order kinetics. The thermodynamic parameters revealed spontaneous and exothermic adsorption of MG dye over SnO₂-SBB nanocomposites. A maximum adsorption capacity (q_max) of 52.64 ± 0.03 for 0.3 SnO₂-SBB and 73.86 ± 0.05 for 0.5 SnO₂-SBB nanocomposites was observed. The newly synthesized SnO₂-SBB nanocomposites showed negative zeta potential, which facilitated the adsorption of hydrated cationic dye molecules due to the electrostatic force of attraction.