Upcycling Agricultural Byproducts into High-performance Adsorbents for Water Remediation

Abstract

Agricultural by-products are generated in substantial quantities, and their disposal or burning can contribute to environmental pollution. This review examines the potential of agricultural residues as raw or modified biosorbents for removing contaminants from water and wastewater. It considers representative materials derived from fruit stones, husks, shells and plant residues, together with their reported performance in removing metal ions, dyes and selected organic pollutants. The reviewed studies describe adsorption processes involving surface functional groups and mechanisms such as electrostatic interactions, ion exchange, complexation and physical adsorption. Material composition, porosity, surface modification, solution pH, initial pollutant concentration and contact time influence reported adsorption performance. Chemical and physical treatments can improve sorption properties, although their effectiveness depends on the biomass source and target contaminant. The reported findings also show that pollutant removal may differ between controlled laboratory solutions and complex wastewater matrices, where coexisting substances can affect adsorption. Consequently, performance estimates obtained under different experimental conditions require cautious interpretation. The review identifies regeneration, treatment of pollutant-loaded adsorbents, application to real wastewater and integration with other treatment technologies as important considerations for practical use. Overall, agricultural by-products offer potential feedstocks for wastewater-treatment adsorbents while providing an opportunity to reuse solid residues. Further evaluation under representative operating conditions is needed before broader application can be established.