Preparation of CTS/PAMAM/SA/Ca2+ hydrogel and its adsorption performance for heavy metal ions

As a new functional polymer material with three-dimensional polymer network structure, hydrogel is widely used in the removel of heavy metal ions pollutants in sewage. In this work, semi-dissolution acidification sol–gel transition method was used to prepare the hydrogel with chitosan/sodium alginate/calcium ion (CTS/SA/Ca2+) physical cross-linked double network structure without adding chemical cross-linking agent. Meanwhile, hyperbranched polyamide-amine with different generations which was rich in amino groups were introduced to improve the adsorption capacity of hydrogel, and the CTS/PAMAM/SA/Ca2+ hydrogel adsorbent with no secondary pollution, environmental protection and high adsorption capacity was obtained. Experimental results show that the hydrogel with third-generation hyperbranched polyamide-amine have the best comprehensive performance. Its maximum adsorption capacities for copper ions and cadmium ions could reach 174.82 mg/g and 157.72 mg/g respectively. Furthermore, it was found that the adsorption behaviors of copper ions and cadmium ions on the hydrogel conformed to the pseudo-second-order kinetic model and Langmuir adsorption isotherm model by studying the factors affecting the adsorption process. The CTS/PAMAM/SA/Ca2+ hydrogel has the advantages of high heavy metal ion adsorption capacity, uniform structure, and recyclability. As a functional material with simple preparation and excellent performance, it has good application potential and research value.