Removing copper ion from wastewater by surface precipitation using novel hierarchical hydrated magnesium carbonate crystal

It is significant to develop a low-cost, easy-to-separate and efficient adsorbent to remove heavy metals from wastewater. Therefore, the hierarchical hydrated magnesium carbonate (HMC) crystal is prepared. The perfor-mances of HMC crystal at different adsorption conditions are studied. The surfaces of HMC crystal before and after Cu2+ adsorption are characterized by XRD, FTIR, XPS, SEM and EDS mapping. The removal efficiency of Cu2+ reaches 99 % under the conditions of an initial concentration of 300 mg/L, HMC dosage of 0.5 g/L, pH value of 4.5 and adsorption time of 180 min. The adsorption kinetic and isotherm can be described by the pseudo-second-order model and Langmuir adsorption model, respectively. The maximum adsorption capacity of Cu2+ is 1406 mg/g. The hierarchical structure provides HMC crystal with sufficient hydroxide ions for Cu2+ surface precipitation and large particle size (40-100 mu m) for subsequent solid-liquid separation, presenting a promising application prospect in the future.