Oral medical wastewater with heavy metal ions (such as plumbum, Pb2+) is regarded as the main pollutant produced in the oral cavity diagnosis, and the treatment process can pose a serious threat to human health. The removal of Pb2+ from oral medical wastewater facing major difficulties and challenges. Therefore, it is of great significance to take effective measures to remove Pb2+ by using effective methods. A new activated three-dimensional framework carbon (3D AFC), regarded as the main material to remove Pb2+ in the oral medical wastewater, has been fabricated successfully. In this experiment, the effects of 3D AFC absorbing Pb2+ under different conditions (including solid-to-liquid ratio, pH, ionic strength, contact time, and initial concentration, etc.) were discussed. And the result revealed that the adsorption kinetics process of Pb2+ on 3D AFC conformed to the pseudo-second-order model and the adsorption isotherm conformed to the Freundlich model. Under the condition that pH = 5.5 and T = 298 k, the calculated maximum adsorption capacity of 3D AFC for Pb2+ was 270.88 mg/g. In practical application, it has strong adsorption ability for Pb2+ in oral medical wastewater. Thus, 3D AFC shows promise for Pb2+ remove and recovery applications because of high adsorption capacity for Pb2+ in oral medical wastewater due to its high specific surface area, outstanding three-dimensional network structure.

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.

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