Utilization of cyanobacterial adsorbents for remediation of lead ions from contaminated water: Insights into bioremediation strategies

This study investigates the adsorption mechanism of lead ions (Pb²⁺) on various forms of cyanobacterium Phormidium corium NRMC-50 adsorbents, such as exopolysaccharides (EPSs), capsular polysaccharides (CPSs), biomass without capsular polysaccharides (BCPSs), and native biomass (NB). An in-depth characterization of Pb²⁺ -loaded adsorbents was carried out to understand the changes that might have happened in their functional groups, surface morphology, elemental composition, and surface charge, due to adsorption. Further, Langmuir, Freundlich, and One-site-specific binding models were applied to investigate the effects of environmental parameters namely, temperature, pH, and initial Pb²⁺ concentrations on adsorption kinetics. Amongst all the adsorbents, polysaccharides exhibited the rapid removal efficiency of Pb²⁺, which might be attributed to the presence of functional groups such as carboxyl, hydroxyl, and amino groups in polysaccharides facilitating efficient Pb²⁺ adsorption. EPS demonstrates a high potential for rapid Pb²⁺ capture due to its high density of binding sites and substantial capacity. Box-Behnken model optimization confirms that pH and Pb concentrations in its environment significantly influence Pb²⁺ adsorption. Overall, this study underscores the efficacy of cyanobacteria in bioremediation applications, offering a sustainable and effective approach to mitigating heavy metal contamination in water systems and contributing to develop more efficient wastewater treatment solutions.