Nitrate removal from aqueous solution using granular chitosan-Fe(III)–Al(III) complex: Kinetic, isotherm and regeneration studies

Abstract In order to effectively remove nitrate from aqueous solution and reduce environmental and health risks caused by excess nitrate in natural water bodies, granular chitosan-Fe(III)-Al(III) complex was prepared through precipitation method and characterized using some techniques such as SEM, XRD, BET, FTIR and XPS. Adsorption performance was optimized by full factorial design. Kinetic and isotherm models were used to analyse experimental data, and reusability was also investigated. Adsorption mechanisms were primarily dominated by ion exchange and electrostatic attraction. pH and temperature had a slightly adverse influence on nitrate adsorption. Specific rate constant was found to be more suitable for the description of adsorption kinetics than observed rate constant. The extended Freundlich isotherm could reasonably describe the competition between nitrate and sulphate ions in a binary component system. Chitosan-Fe(III)–Al(III) complex had high mechanical strength, good acid–alkali resistance and reusability, suggesting a promising potential of practical application.