Low-cost novel silica@polyacrylamide composites: fabrication, characterization, and adsorption behavior for cadmium ion in aqueous solution

Pollution during rapid industrialization process is a serious environmental problem that seriously affects people's lives and livelihoods. Among them, the pollution of excessive heavy metals in wastewater has attracted wide attention. The current study proposes a novel effective and low-cost silica@polyacrylamide composites (SP-C) to capture cadmium ion (Cd2+) from wastewater contaminated by heavy metal. The chemical and physical properties of the surface and interior of silica@polyacrylamide composites were studied by different characterization methods. The adsorption capacity and kinetics of cadmium ions in aqueous solutions using silica@polyacrylamide composites were also studied, and some discussions about the mechanism of adsorption process were made. Silica@polyacrylamide composites showed enhanced cadmium ions adsorption with the maximum adsorption capacity of 211.86 mg/g (pH 6.5, T = 318.15 K), which was fitted by Langmuir model. The adsorption experimental kinetic data of silica@polyacrylamide composites could be excellently verified by pseudo-second-order model. Moreover, a comparison of the cost between the proposed silica@polyacrylamide composites and other reported adsorbents is provided. And the results indicate that the silica@polyacrylamide composites adsorption cost is 0.16 $/g cadmium ion, which means a promising cost-effective adsorbent for cadmium ion removing.