Synthesis of TiO2/nZVI nanocomposite for nitrate removal from aqueous solution

To develop a new adsorbent for removal of nitrate and to enhance the adsorbent separation from aqueous solution, surface modifcation of titanium dioxide nanoparticles with nano-zero-valent iron (nZVI) was performed through chemical coprecipitation of magnetic nanoparticles on TiO2 surface. Morphological, structural and magnetic properties of modifed adsorbents (TiO2/nZVI) were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray difraction (XRD), Fourier transform infrared radiation (FTIR) and vibrating sample magnetometer (VSM). To determine the ionic strength efect and optimal removal conditions, the efect of contact time (60–210 min), pH (4–10) and adsorbent dosage (0.5–1.5 g/L) on adsorption efciency were studied, using response surface method. Obtained results showed that the nitrate removal efciency decreased with increasing ionic strength. The TiO2/nZVI nanocomposites exhibited a ferromagnetic behavior and its saturation magnetization was 795.28 memu/g. The maximum nitrate removal (98.226%) achieved by modifed TiO2 was about 14.65% higher than the unmodifed nanoparticles. The optimized adsorption parameters were: adsorbent dosage 0.982 g/L, pH 4.185 and the contact time 150.091 min.