HIGH-EFFICIENCY REMOVAL OF Cu 2+ , Hg 2+ ANDCr 3+ FROMSYNTHETIC WATER BY CHITOSAN: ADSORPTION PERFORMANCE AND MECHANISM
The accumulation of heavy metals in aquatic environments has appeared as a serious environmental and publichealth worry worldwide. In this work, the adsorption potential of chitosan, a renewable and biodegradablebiopolymer, was quantified for the removal of Cu 2+ , Hg 2+ and Cr 3+ ions from hydric media. Batch adsorption studieswere conducted, and the residual metal ion concentrations were meticulously calculated with the help of AtomicAbsorption Spectroscopy (AAS). Adsorption was strongly pH-dependent, with optimum performance observedat pH 5 due to favourable electrostatic contacts among metal ions and chitosan functional groups. Increasing the initial metal concentration (10–100 mg/L) reduced removal efficiency owing to saturation of active sites, whereas higher adsorbent dosages enhanced metal uptake. Analysis with the Langmuir adsorption isotherm discovered maximumadsorption of 6.433 mg/g for Cu 2+ , 5.360 mg/g for Hg 2+ and 3.774 mg/g for Cr 3+ . The findings demonstrate thepotential of chitosan as a naturally derived, biodegradable, and effective adsorbent for the removal of toxic metal ions from water, thereby contributing to the United Nations Sustainable Development Goal 6 (SDG-6): Clean Water and Sanitation
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