Optimization of iron removal in water by nanobubbles using response surface methodology

Abstract

Iron contamination, causing staining, discoloration and bad taste, is a worldwide water problem. It is necessary to focus on iron oxidation from the water. This work aims to develop nanobubbles (NBs) technology to remove iron (Fe2þ) from aqueous solutions. In batch experiments, the effects of initial Fe2þ concentration, pH, and aeration pressure on the Fe2þ oxidation efficiency were carried out. The results showed that initial concentrations, pH and aeration pressure are significant parameters influencing Fe2þ oxidation. On the basis of single factor experiments, the Box–Behnken design was used to optimize the Fe2þ oxidation conditions with NBs using three parameters (Fe2þ concentration, pH, and aeration pressure) under the response surface methodology. The optimal Fe2þ oxidation was achieved when the initial concentration was 13.7 mg·L-1, pH ¼ 9, and the aeration pressure was 290 kPa. The regression model of Fe2þ oxidation rate under optimized test conditions is accurate and effective. The results showed that the combination of single factor test and response surface optimization can be used to optimize the Fe2þ oxidation process with NBs. It is concluded that NBs technology is promising for Fe2þ oxidation from water.