Fabrication of 3D Gelatin Hydrogel Nanocomposite Impregnated Co-Doped SnO2 Nanomaterial for the Catalytic Reduction of Environmental Pollutants.

In the catalytic reduction of various environment pollutants, cobalt-doped tin oxide, i.e., Co-SnO2 intercalated gelatin (GL) hydrogel nanocomposite was prepared via direct mixing of Co-SnO2 doped with GL. Then, it was crosslinked internally using formaldehyde within a viscous solution of gelatin polymer, which led to the formation of GL/Co-SnO2 hydrogel nanocomposite. GL/Co-SnO2 hydrogel nanocomposite was fully characterized by using field-emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). The FESEM images indicate that the Co-SnO2 composite has a spherical structure on the GL matrix while EDX elucidates the elemental composition of each atom in the crosslinked GL/Co-SnO2 hydrogel nanocomposite. The GL/Co-SnO2 nanocomposite was checked for the reduction of various pollutants, including 2-nitro-phenol (2-NP), 2,6-dinitro-phenol (2,6-DNP), 4-nitro-phenol (4-NP), Congo red (CR), and methyl orange (MO) dyes with a strong sodium borohydride (NaBH4) reducing agent. The GL/Co-SnO2 nanocomposite synergistically reduced the MO in the presence of the reducing agent with greater reduction rate of 1.036 min-1 compared to other dyes. The reduction condition was optimized by changing various parameters, such as the catalyst amount, dye concentration, and the NaBH4 amount. Moreover, the GL/Co-SnO2 nanocomposite catalyst can be easily recovered, is recyclable, and revealed minimal loss of nanomaterials.