Preparation of magnesium hydroxide/diatomite composites by in-situ precipitation method and adsorption of methyl orange

Abstract

In view of the environmental pollution caused by organic dye wastewater in the process of economic development， magnesium hydroxide/diatomite composites are prepared by the in-situ precipitation method， and their adsorption performance is studied with methyl orange as the target pollutant. The magnesium hydroxide/diatomite composites are characterized by XRD， SEM， FT-IR and BET. The adsorption effects of the dosage， initial pH value， and initial concentration of the target pollutant on methyl orange are explored. The results show that the adsorption effect is the best when the dosage of magnesium hydroxide/diatomite is 0.5 g， the pH value is 8， and the concentration of methyl orange is 8 mg/L， and the adsorption rate of the composite reaches 93.34%. Compared with modified diatomite， the adsorption rate increases by 41.34%. The adsorption kinetics model， isothermal adsorption model， and adsorption thermodynamic model are used to analyze the adsorption process. The results show that the adsorption process is spontaneous endothermic and entropy-increasing， which conforms to the Freundlich isothermal adsorption model and quasi-second-order kinetic model， with chemical adsorption as the main mechanism. The composite material shows good reusability in cyclic verification experiments.

Keywords

• magnesium hydroxide/diatomite composites
• modification
• adsorption
• methyl orange