Activated Biochar from Pineapple Crown Biomass: A High-Efficiency Adsorbent for Organic Dye Removal

Renowned for its versatility in environmental applications, biochar exhibits substantial potential to enhance anaerobic digestion, facilitate carbon sequestration, and improve water treatment through its highly efficient adsorption mechanisms. This study focuses on biochar derived from pineapple crown biomass, produced through slow pyrolysis, and its efficiency in removing organic dyes from contaminated water. The structural, morphological, and surface properties of both biochar and chemically activated biochar samples were comprehensively characterized using a range of techniques, including XRD, FTIR, XPS, BET surface area analysis, and SEM microscopy. The adsorption performance was evaluated using methylene blue (MB), rhodamine B (RhB), and malachite green (MG) dyes as model contaminants, with particular emphasis on the contact time on dye removal efficiency. Initial results showed removal rates of 10.8%, 37.5%, and 88.4% for RhB, MB, and MG, respectively. Notably, chemical activation significantly enhanced the adsorption efficiency, achieving complete (100%) removal of all tested dyes. Complete adsorption of MB and MG occurred within 9 min, indicating rapid adsorption kinetics. Adsorption data fit well with pseudo-second-order kinetics (R2 = 0.9748–0.9999), and the Langmuir isotherm (R2 = 0.9770–0.9998) suggested monolayer adsorption with chemical interactions between dyes and biochar. The intraparticle diffusion model further clarified the adsorption mechanisms. These findings demonstrate the efficacy of activated biochar for dye removal and highlight the potential of pineapple crown biomass in environmental remediation.