Highly efficient and selective removal of cadmium from aqueous solutions based on magnetic graphitic carbon nitride materials with molecularly imprinted polymers

Poly (N-isopropyl acrylamide) grafted and modified g-C3N4 magnetic imprinted ions polymers (IIP) was prepared by selecting Cd2+ as a template ion. Some techniques were applied to characterize morphology and property of IIP including Scanning electron microscope (SEM), Thermo-gravimetric analyzer (TGA), Infrared Spectroscopy (IR) and Vibrating sample magnetometer (VSM). The adsorption capacity of IIP for various metal ions was contrasted and the influence of different factors for adsorption of Cd2+ was investigated. These results showed that the IIP was the large block morphology and had selectivity for Cd2+ adsorption. The experimental data were well described by Langmuir isotherm model and pseudo-second-order model. The predicated maximum adsorption capacity of IIP for Cd2+ is 258.35 mg/g. The maximum adsorption capacity obtained from the experiment is 184 mg/g (initial concentration of 250 mg/L, pH=6.0, contact time for 180 min) at 303 K. The parameters of adsorption activation energy suggested that there is chemisorption and physical adsorption on the adsorption of Cd2+. The results of adsorption mechanism suggested that IIP selectively adsorbs Cd2+, which not only relies on ion holes, but also depends on functional groups. The adsorption capacity of IIP for Cd2+ could still keep 84% in the fifth consecutive adsorption-regeneration cycle. Hence, IIP would be regarded as a selective and high adsorption capacity magnetic adsorbent in removal of Cd2+ from wastewater. (C) 2020 Elsevier B.V. All rights reserved.