Effects of Fe3O4 magnetic nanoparticles on nitrate removal efficiency: an optimization study using response surface methodology

The nitrate contamination of water resources is a serious environmental problem, which may be solved by nitrate sorption onto magnetic nanoparticles. In this study, the effects of Fe3O4 magnetic nanoparticles on nitrate removal were investigated. Fe3O4 was synthesized by a co-precipitation method and used as an adsorbent for nitrate removal. pH, adsorbent dosage, and contact time were considered as the main variables. The effective ranges of these variables were chosen as pH = 4–10, adsorbent dose = 0.5–1.5 g/L, and contact time = 30–90 min. The optimization study was conducted using the Box-Behnken statistical design method. According to the analysis of variance table, it can be concluded that the model is ‘significant’ and the value of R2 was 0.99. The results of the study show that the maximum nitrate removal efficiency was about 91.02%. This was obtained at pH 7, using a dose of 1.3 g/Lof Fe3O4, and a contact time of 28 min.