Utilization of nanocrystalline and tin-doped titanium dioxide synthesized by polyvinyl polymer sol-gel for phenolic compound degradation

Abstract

This study was aimed at using the synthesized TiO2 nanocrystalline for photodegradation of phenolic compound. The synthesized TiO2 nanocrystalline was prepared by sol-gel method using Polyvinyl Pyrrolidone (PVP) with Titanium (diisoproproxide) bis (2,4-pentanedionate) 75 wt% in 2-propanol (TIAA) and doped with tin (Sn). Using 2%Sn doped on TiO2 and calcined at 550 oC provided the most appropriate properties of TiO2/Sn referred as to TiO2/Sn2. Both individual and mixed phenolic compound solutions (phenol, guaiacol, and syringol) with commercial TiO2 and TiO2/Sn2 were tested for phenolic compound degradation. Addition of Sn promoted an increasing surface area, but at the mean time it accelerated the phase transformation of anatase to rutile. The occurrence of photocatalytic reaction’s intermediates indicated a less number of intermediate producing for using TiO2/Sn2 compared to the commercial TiO2 for all the experiments. However, both of the synthesized and commercial ones produced hydroquinone for phenol degradation which is considered as harmful to the environment. Notably, after completing degradation of phenol, all intermediates would substantially disappear. Photocatalytic degradation of the individual and mixed phenolic compound by the synthesized TiO2/Sn2 and the commercial TiO2 were significantly different. The TiO2/Sn2 presented the consistency of photocatalytic degradation of both individual and mixed phenolic compound solution. It also presented the highest degradation efficiency of methoxy phenol (guaiacol and syringol). The commercial TiO2 presented the inconsistency of the degradation between the mixed and individual compounds. The commercial one presented the higher degradation for the individual phenol solution, but not for the degradation of phenol in the mixed solution. For the real wastewater (pulp and paper wastewater) study, after 6 hours irradiation, the synthesized TiO2/Sn2 exhibited the better performance for the mixed methoxy phenol compounds. This performance was the same as the results obtained from the synthetic mixed phenolic compound solution. Both commercial and synthesized ones could not perform well on phenol degradation in the mixed phenolic compound solution. This is possibly due to the insufficient irradiation time.