Cyclic Adsorption and Desorption Characteristics of Citric Acid-chitosan Variant Resins for Pb, Fe, and Zn Removal from Simulated Mining and Agricultural Wastewater System

Targeted sorbents for the real-world adsorptive separation of heavy metals shall exhibit high sorption capacity, reusability, and cost-effectiveness. In this study, a novel composite sorbent has been synthesized for the concurrent mitigation of iron, lead, and zinc metal ions from synthetic wastewater systems. For this purpose, chitosan with alternate molecular weight (low, medium, and high) and with hydroxyl and amine functional groups was employed as a substrate. The successful anchoring of the organic compound citric acid was achieved with the glutaraldehyde crosslinker. The medium molecular weight chitosan-citric acid (medium Cit-CS) has been evaluated to achieve optimal metal uptake of 243.90, 3.93, and 144.93 mg g⁻¹ for zinc, lead, and iron from intricate Zn dominant adsorbate system. Accordingly, it was ascertained that other alternative ions in the adsorbate system significantly alter the sorption patterns. The validation of the chemisorption process was effectively established through the consistency observed in the pattern of adsorption as well as the successful modeling via the pseudo-second-order (PSO) approach. Following this, the desorption of metal ions was effective with simple basic and acidic eluents and for a three-cycle-based simultaneous regeneration. In summary, the findings demonstrate the promising performance of the sorbent for metal ions eradication from intricate solutions.