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

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 (Fe2+) from aqueous solutions. In batch experiments, the effects of initial Fe2+ concentration, pH, and aeration pressure on the Fe2+ oxidation efficiency were carried out. The results showed that initial concentrations, pH and aeration pressure are significant parameters influencing Fe2+ oxidation. On the basis of single factor experiments, the Box–Behnken design was used to optimize the Fe2+ oxidation conditions with NBs using three parameters (Fe2+ concentration, pH, and aeration pressure) under the response surface methodology. The optimal Fe2+ oxidation was achieved when the initial concentration was 13.7 mg·L−1, pH = 9, and the aeration pressure was 290 kPa. The regression model of Fe2+ 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 Fe2+ oxidation process with NBs. It is concluded that NBs technology is promising for Fe2+ oxidation from water.