Optimization for removal efficiency of fluoride using La(III)-Al(III)-activated carbon modified by chemical route

Abstract

A simple chemical route was adopted for the preparation of adsorbent to remove fluoride in the simulation solution. In this study, commercially activated carbon (CAC) was used as the raw material, HNO3 (20 wt%), La(NO3)3·2H2O (0.05 mol/L), and Al(NO3)3 (0.10 mol/L) were employed as modification reagents to successfully prepare the CAC adsorbent loaded with the elements La and Al (La(III)-Al(III)-CAC). The modified adsorbent was characterized by scanning electron microscopy, energy-dispersive spectroscopy, and Fourier-transform infrared spectroscopy measurements. The effects of variables such as solution pH, adsorption time, initial concentrations, and volume of solution were investigated on adsorption efficiency by the response surface method (SM). Under optimum conditions, specified as a pH value of 6, an adsorption time of 1.2 h, an initial concentration of 30 mg/L, a solution volume of 25 mL, and the value of F can reach at 74.11%. From the SM analysis, the pH value was a significant factor in the adsorption process and the order for these key factors was as follows: PH > adsorption time > solution volume. Meanwhile, there were interactions among these factors. Chemical modification had an important role in pore structure generation and functional group of adsorbent to improve the adsorption efficiency. The removal performance of adsorbent on simulation solution of fluoride also showed the feasibility of adsorbent to be applied in industrial purposes.