Adsorption of Cd(II) from aqueous solutions via meso structured adsorbent based on Ni/Mo-LDH: kinetics, thermodynamics, and adsorption mechanism

This paper deals with cadmium ions removal from aqueous solutions by Ni/Mo-layered double hydroxide with kinetics and thermodynamics studies. At temperature of 318 K, pH = 5.5, adsorbent mass of 0.5 g/L, time of 105 min, and initial Cd(II) concentration of 175 mgL–1, the maximum adsorption capacity reached to 68.4 mg/g. The adsorption processes followed pseudo-second-order model and Langmuir isotherm and the calculated thermodynamic parameters concluded that the adsorption process was spontaneous, thermally dependent, and endothermic in nature. Therefore, the adsorption mechanism was proposed through multilayer surface adsorption by coordination of cadmium ions with hexavalent molybdenum (Mo6+) and also the coexisting ions effect on removal was detected.