Preparation of modified reed carbon composite hydrogels for trapping Cu2+, Ni2+ and methylene blue in aqueous solutions

The pollution of heavy metal ions and organic dyes seriously endangers human health and causes acute environmental problems. The adsorption method is extensively adopted in the treatment of water pollution which is more harmful to human health. In this work, the original reed carbon (ORC) was functionalized by polyethyleneimine (PEI). By means of radical polymerization, PEI-modified reed carbon (PRC), sodium alginate and lysine were made into carbon-composite acrylic hydrogel (SA/LS/PRC). Meanwhile, SEM, FTIR, TGA, and Zeta potential were used to characterize the adsorbent. The elimination capacity of SA/LS/PRC for Cu2+, Ni2+, and Methylene blue (MB) was researched through batch adsorption experiments. The adsorption behavior of SA/LS/PRC is more suitable for the pseudo-second-order kinetic model of chemical removal of pollutants and the Langmuir model relying on monolayer adsorption. The maximum adsorption capacities of SA/LS/PRC for Cu2+, Ni2+ and MB are 1245.27, 1239.47 and 627.29 mg g-1, respectively, and the adsorption performance is better than those reported in most literatures. The interaction of Cu2+, Ni2+, and MB were studied via binary mixed adsorption experience. Surface complexation and electrostatic interactions are the major removal mechanisms for contaminants. The adsorption capacity of SA/LS/PRC kept above 81% after five cycles. The SA/LS/PRC green hydrogel can be effectively applied in the mixed adsorption process of heavy metal ions and the removal of dyes.