Nano mesocellular foam silica（MCFs）:An effective adsorbent for removing Ni2+ from aqueous solution

Nano mesocellular foam silica(MCFs)was synthesized through the hydrothermal method in this study.Powder X-ray diffraction and scanning electron microscopy were used to characterize the MCFs sample.The sample presented spherical particles and regular morphology.The results of transmission electron microscopy showed that synthesized MCFs has a three-dimensional honeycomb pore structure,which aids in the adsorption of nickel ion(Ni^2+).The results of low-temperature nitrogen gas adsorption-desorption showed that the pore diameter of the synthesized MCFs was 19.6 nm.The impacts of pH,temperature,amount of adsorbent,initial concentration of Ni^2+,and contact time on the adsorption effect of Ni^2+ by MCFs were studied.Under the optimized adsorption conditions,the adsorption rate reached 96.10%and the adsorption capacity was 7.69 mg/g.It has been determined through the study of kinetics and adsorption isotherms that the adsorption of Ni^2+ by MCFs follows the pattern of the pseudo-second-order kinetic model,simultaneously belonging to the Freundlich adsorption type.The thermodynamic results of adsorption showed that,when the temperature is between 25℃ and 45℃,the adsorption is a spontaneous exothermic reaction.