Excessive iron and manganese presented in groundwater sources may cause harm to human health that needs to be solved urgently. This research aims to develop high-performance Mn/Ti-modified zeolites using sol-gel method and hydrothermal synthesis method to remove Fe2+ and Mn2+ simultaneously. The preparation parameters were optimized by response surface methodology, and the results confirmed that the optimal preparation conditions were as follows: mass ratio of MnO2-TiO2/zeolite = 1, hydrothermal temperature = 200°C, and calcination temperature = 500°C. The results of batch adsorption experiments showed that the best removal rate of Fe2+ and Mn2+ by modified zeolite materials which was prepared under the optimum conditions reached 96.8% and 94.4%, respectively, at which the saturated adsorption capacity was 2.80 mg/g and 1.86 mg/g. Through the adsorption kinetics, thermodynamics, internal diffusion, and isothermal adsorption analyses, it is confirmed that the adsorption process of Fe2+ and Mn2+ by the modified zeolite is mainly chemical adsorption. The results of the Weber-Morris internal diffusion model prove that internal diffusion is not the only step that controls the adsorption process. In addition, combined with the characterization of the composite-modified zeolite and the adsorption experimental study, it shows that there is an autocatalytic reaction in the adsorption process.
Keywords: Cation removal; Nano MnO2-TiO2; Removal mechanism; Response surface methodology; Zeolite.
© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.