Preparation of basic magnesium carbonate nanosheets modified pumice and its adsorption of heavy metals

Heavy metal pollution in wastewater poses a grave danger to the environment and the human body. Pumice is a mineral with abundant reserves and low prices, and its prospect of heavy metal adsorbent is very broad. In this work, we modified pumice with basic magnesium carbonate nanosheets by a convenient hydrothermal synthesis. The adsorption capacity of heavy metals is greatly improved. The effects of different pH and adsorption dosages are investigated. All the optimum pH values for Cu²⁺, Pb²⁺, and Cd²⁺ are 5. The adsorption of three kinds of ions conforms to the quasi-second-order adsorption kinetics model. The theoretical adsorption capacities of Cu²⁺, Pb²⁺, and Cd²⁺, which are calculated by the Langmuir model, are 235.29 mg/L, 595.24 mg/L, and 370.34 mg/L, respectively. The adsorption of Cu²⁺ and Cd²⁺ fit the Langmuir model better. The Freundlich model is fitted well with the adsorption of Pb²⁺. In the experiment simulating real wastewater, the adsorption capacity of heavy metals is not affected. It also shows good reusability in three regeneration cycles. And Mg₅(CO₃)₄(OH)₂·4H₂O@pumice adsorption column showed the good removal efficiency of three heavy metals at different concentrations and different spatial velocities in the column experiment. Thus, it is believed that the Mg₅(CO₃)₄(OH)₂·4H₂O@pumice is a promising adsorbent for the efficient removal of heavy metals.