Amidoxime and carboxylate-containing polymer adsorbents derived from acrylic yarn exhibit high adsorption capacity for lead(ii) (Pb2+) ions in water. The adsorption process follows pseudo-second-order kinetics and fits the extended Langmuir isotherm model with the maximum adsorption capacity of Pb2+ with 238 mg lead per gram of the fiber at room temperature. Endothermic (ΔH° = 20.3 kJ per mole), spontaneous, and with the increase in the entropy of Pb2+ adsorption was observed from the thermodynamic studies. Dynamic column adsorption experiments showed that the fiber can process 4.3 L of water spiked with 1 ppm of lead(ii) solution at a flow rate of 4.4 mL per min under the specified conditions. The selectivity of Pb2+ with the competitive metal ions showed varying results with highly selective for Pb2+ in a binary solution with sodium and calcium and varying degrees of competitiveness with transition metal ions. This efficient and easily prepared fiber adsorbent appears to be a promising new material for the remediation of lead-contaminated aquatic environments and potable waters.
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