Maize stem-derived bio adsorbent for manganese removal: from agricultural waste to water remediation
摘要
The abundance of agricultural waste and improper disposal pose significant environmental hazards, including greenhouse gas emissions, resource depletion, and pollution in various forms. However, innovative upcycling techniques can repurpose agricultural waste into valuable adsorbents for environmental remediation. This study explores the novel valorization of maize stem, a widely available yet underexploited agrarian waste, into an efficient adsorbent material for manganese (Mn2+) removal from aqueous solution. Maize stem waste was pyrolyzed to produce biochar, which was further activated using chemical methods to obtain activated carbon. Activation was done by utilizing NaOH, ZnCl2, and H3PO4. The char was then cleaned with deionized (DI) water to achieve a pH 7 and oven-dried overnight at 110 °C. The prepared biochar was characterized using SEM, EDS, FTIR, and BET analysis. The characterization results showed that the biochar treated with NaOH has improved morphological and functional characteristics. BET surface area analysis revealed a pore size of 6.4 nm and a large surface area of 3.82 m2/g for the adsorbent treated with NaOH. A maximum Mn2+ removal efficiency of 99.4% was achieved using 0.45 g of adsorbent, with an optimized adsorption capacity of 2.64 mg/g at pH 7, contact time of 3 h, and room temperature. The findings concur that biochar derived from maize stems is a promising, low-cost, and eco-friendly adsorbent for effectively removing Mn2+ from aqueous solution. By valorizing agricultural waste, this research addresses the dual challenges of waste management and water purification, contributing to sustainable practices aligned with circular economy principles.