Eco-Friendly Adsorbent: Insights Into the Performance and Adsorption Mechanisms of Banana Fruit Shaft Biochar for the Removal of Mn(II), Cd(II), Pb(II), and Cu(II)

Abstract

Exploring cost-effective and high-performance adsorbents plays a crucial role in the efficient utilization of agricultural waste and the remediation of heavy metal contamination in water bodies. This study focuses on preparing biomass carbon (BC) from banana pseudostems for the remediation of heavy metals in water. A systematic investigation was conducted to evaluate the effects of initial solution concentration, pH, reaction time, reaction temperature, and coexisting cations on the adsorption of Mn(II), Cd(II), Pb(II), andCu (II) by BC. The results showed that the adsorption capacity of BC for all four heavy metals reached its peak at pH 6. The adsorption process was primarily governed by monolayer chemisorption. Furthermore, the process is spontaneous, endothermic, and accompanied by an increase in entropy. In a multimetal system, BC demonstrated the strongest selectivity for Pb(II). Even in the presence of interfering ions, BC maintained a high adsorption capacity for heavy metals. Notably, after 5 cycles of use, BC retained a significant removal rate of 40%–60% for heavy metals, underscoring its recyclability and environmental friendliness. Characterization studies indicated that the adsorption of heavy metals by BC involves multiple mechanisms, including ion exchange, mineral precipitation, functional group complexation, and cation-π interactions. The dissolved organic matter (DOM) derived from biochar plays a pivotal role in the adsorption process. Furthermore, the preparation of BC is both straightforward and cost-effective, combining economic viability with practical applicability.