MAIZE STEM DERIVED BIO ADSORBENT FOR MANGANESE REMOVAL: FROM AGRICULTURAL WASTE TO WATER REMEDIATION

Abstract

The abundance of agricultural waste and its improper disposal pose a significant environmental hazard. This waste contributes to greenhouse gas emissions, the depletion of valuable resources, and pollution in various forms. However, innovative upcycling techniques can repurpose agricultural waste into valuable adsorbents for environmental remediation. This study focuses on the conversion of widely generated maize stem agricultural waste into an adsorbent for manganese removal. Maize stem waste was collected and crushed to achieve a 200 mm particle size followed by activation. Activation was done by utilizing NaOH, ZnCl2, and H3PO4. The char was then cleaned with DI water to achieve a neutral pH and oven dried overnight at 110°C. The prepared biochar was characterized utilizing different techniques including SEM, EDS, FTIR, and BET analysis. The characterization results showed that the biochar treated with NaOH has improved morphological and functional characteristics. Morphological analysis confirmed the presence of pores in the activated biochars in contrast to pristine char. BET surface area analysis revealed a pore size of 6.4 nm, a large surface area, of 3.82 m2g-1 for the adsorbent treated with NaOH. The batch adsorption studies revealed that the adsorption followed the langmuir isotherm for manganese removal. 99.4 % of Mn2+ was removed at 0.45 g of adsorbent dosage. The optimized adsorption conditions reveal the maximum adsorption capacity of 1.32 mg/g was achieved at neutral pH with 3 hours as contact time when operated at room temperature. The findings concur that biochar derived from maize stem is effective for removing manganese from water sources.