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 modification of titanium dioxide nanoparticles with nano-zero-valent iron (nZVI) was performed through chemical coprecipitation of magnetic nanoparticles on TiO 2 surface. Morphological, structural and magnetic properties of modified adsorbents (TiO 2 /nZVI) were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared radiation (FTIR) and vibrating sample magnetometer (VSM). To determine the ionic strength effect and optimal removal conditions, the effect of contact time (60–210 min), pH (4–10) and adsorbent dosage (0.5–1.5 g/L) on adsorption efficiency were studied, using response surface method. Obtained results showed that the nitrate removal efficiency decreased with increasing ionic strength. The TiO 2 /nZVI nanocomposites exhibited a ferromagnetic behavior and its saturation magnetization was 795.28 memu/g. The maximum nitrate removal (98.226%) achieved by modified TiO 2 was about 14.65% higher than the unmodified nanoparticles. The optimized adsorption parameters were: adsorbent dosage 0.982 g/L, pH 4.185 and the contact time 150.091 min.