Ion-imprinted thermosensitive chitosan derivative for heavy metal remediation

Ion-imprinted thermosensitive chitosan derivative (ITC) was successfully synthesized through a novel gradient heating process towards applications in heavy metal remediation, using Cu²⁺ template paired with N-isopropylacrylamide (NIPAM) monomer. SEM, DSC, FTIR and Raman spectroscopy were used to characterize the structure and properties of ITC. The phase change temperature (PCT) of ITC was 35.31 °C in the heating cycle, whereas in the cooling cycle the PCT for ITC was 26.27 °C. The adsorption capacity of ITC for Cu²⁺ at 45 °C (> PCT) was 88.94 mg/g. Desorption rate of 98.90 % was achieved after washing with ultra-pure water at 20 °C (< PCT). An adsorption capacity of 85 mg/g and a desorption rate of 97 % sustained after five cycles reuse. The adsorption capacity for Cu²⁺ was measured at 80.23 mg/g under other seven interfering metal ions. The adsorption kinetics and adsorption isotherm fitted pseudo-second-order and Langmuir equation, respectively.