Efficient Removal of Nickel from Wastewater by Microwave-Assisted Synthesized Nickel Surface Ion Imprinted Polymer

Abstract

Nickel ion imprinted polymer (Ni-IIP) was prepared using microwave-assisted surface imprinting technique with Ni²⁺ as the template, salicylaldehyde-ethylenediamine Schiff base as functional monomers, ethylene glycol dimethacrylate as a crosslinking agent and alkylated silica gel as a carrier. Fourier transform infrared spectroscopy (FTIR) was used to characterize Ni-IIP, which confirmed the successful synthesis of the polymer. Scanning electron microscopy (SEM) was used to compare the surface morphology of Ni-IIP to non-imprinted polymer (NIP). The SEM analysis found that Ni-IIP had many holes on its surface and abundant spherule structures after elution, while NIP only had a few irregular holes on its surface. The adsorption performance of IIP was studied under different conditions, including pH, temperature, and initial concentration of Ni. The experimental results showed that the maximum adsorption capacity of IIP for Ni was 24.23 mg g^–1 at pH 8, temperature of 30°C, adsorption time of 40 min, and initial concentration of Ni of 30 mg L^–1. The pseudo-second-order kinetic equation could better describe the whole adsorption process, suggesting that chemical adsorption mainly controlled the adsorption process of nickel ions. The Langmuir adsorption isotherm model showed a high linear relationship, and the theoretical adsorption capacity was closer to the actual adsorption capacity, indicating that the adsorption of nickel ions by IIP and NIP occurred in a single layer. Selective experiments showed that IIP had specific selectivity for nickel ions compared with Cu²⁺, Zn²⁺, and Cd²⁺. The results obtained from the analysis of regeneration and practical application demonstrate the promising potential of the prepared Ni-IIP for the efficient removal of nickel pollutants from water sources. These findings provide a new approach to the removal of Ni from wastewater.