Three-Dimensional-Printed Calcium Alginate/Graphene Oxide Porous Adsorbent with Super-High Lead Ion Adsorption Ability in Aqueous Solution

Abstract

Abstract Using three-dimensional (3D) printing technology, a 3D calcium alginate/graphene oxide (3D CA/GO) adsorbent, with a hierarchical macroporous structure, was successfully constructed with a light weight, good structural stability (operability), hydrophilicity, and other excellent properties. Owing to the optimized construction process and controllable construction, the 3D CA/GO showed an enhanced adsorption capacity for lead (Pb2+) in aqueous solution (for example, at pH = 3, the adsorption capacity was 490.2 mg/g, which was two times higher than reported in the literature). Meanwhile, the selective adsorption ratio of 3D CA/GO for Pb2+ reached 99.8% when positive ions occurred. In addition, after eight adsorption-desorption cycles, the adsorption capacity did not experience a significant decrease and the structure remained stable. Meanwhile, the adsorbed Pb2+ could be eluted by hydrochloric acid, thus realizing the recovery, concentration, and recycling of Pb2+. Moreover, through characterization analysis and Ca2+ releasing experiment, we confirmed that the adsorption mechanism of 3D CA/GO consisted of electrostatic interactions, ion exchange and chelation. According to the actual situation, choose the waste water of medical environment, and 3D CA/GO was verified as capable of removing and recycling Pb2+. The immersion experiment using simulation wastewater solution containing heavy metal ions also indicated that 3D CA/GO could maintain structural stability and sustain its adsorption capacity. Its excellent structural stability, strong adsorption capacity, and outstanding selective adsorption capacity were attributed to the controllable construction and optimized structure of hierarchical macroporous materials by 3D printing technology.