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 performances 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 μm) for subsequent solid–liquid separation, presenting a promising application prospect in the future.