Monitoring with HPLC and LC/MS of photocatalytic degradation by S doped nano TiO2 of some textile dyestuffs

In this thesis, photocatalytic degradation conditions of textile dyestuffs such as Reactive Black 5 (RB 5) and Reactive Red 120 (RR 120) with diazo groups, which are categorized, therefore, as persistent organic pollutants were investigated by using S-doped nano-TiO2, as catalyst (S-TiO2) under visible light. Release of these compounds into the environment is unwanted because of coloring effect and their toxic breakdown products might be mutagenic. S-doped Nano-TiO2 synthesized through the reflux method was characterized using XRD, SEM, XRF, UV-vis/DRS and particle size distribution analysis. Photocatalytic degradation conditions for both of the dyes were determined by investigating the parameters such as amount of the catalyst, irradiation time, pH of the medium, pollutant concentration, organic matrix and anion/cation effect. Photocatalytic degradation ratios of RB 5 and RR 120 in the catalysis of S-doped nano-TiO2 were determined at optimum conditions, by using UV/vis spectrophotometer, Total Organic Carbon (TOC) and HPLC analyses. While RB 5 was degraded more than 95 % by S-TiO2 under UV light in 60 min and under visible light in 100 min, RR 120 was degraded more than 95 % under UV light in 100 min and under visible light in 150 min with the same catalyst. Degradation mechanism was tried to be determined by means of monitoring by HPLC and LC/MS by-products or intermediates that can occur during the photocatalytic degradation process. Key Words: Reactive black 5, Reactive red 120, S doped nano TiO2, HPLC, LC/MS