Mineralization study of the reactive red-4 [RR4] dye under photodegradation via immobilized silver [Ag] TiO2 photocatalyst / Nurfarhanah Nadzira Che Razak

The organic dyes from the textile industry released to the water body might result in environmental effects which these dyes are high toxicity and non-biodegradability that must be treated using the photocatalysis process to degrade organic compounds into harmless chemicals. Therefore, several modifications have been approaches to reduce the Eg and electron-hole recombination like doping with Ag, since Ag indicates a beneficial influence on photocatalytic activity. In this work, titanium dioxide (TiO2) was used in the photocatalysis process as a semiconductor due to its unique properties and has less effective under visible light irradiation. Doping with Ag, can reduced photogenerated electron-hole pair recombination, hence enhancing the photocatalytic activity of TiO2. The 3 wt% of Ag on TiO2 (Ag doped TiO2) was prepared by photo deposition method prior immobilization to study the mineralization of 12 mgL-1 RR4 dye under photodegradation using 55 W fluorescent lamp up to 480 mins (8 hrs) irradiation time. TiO2 was coated onto double-sided adhesive tape (DSAT) by using brush technique on glass plate 10 x 1.5 x 0.2 cm (L x H x B) as support material. The diffraction angles obtained in immobilized Ag-doped TiO2 was aligned with TiO2 based on JCPDS card no: 21-1276 with additional peaks appears at 32.7, 35.3, 38.2° representing the peaks for Ag2O. The hydroxyl bonding was observed at 1600-1800 cm-1and the peak detected at 700-900 cm-1 indicates Ag-O vibration which scrutinized by FTIR analysis. The acquired results from FESEM-EDX indicated the presence of 0.6% Ag on the Ag doped TiO2 photocatalyst. Ag doped TiO2 has shown an excellent mineralization process where a complete mineralization was achieved at 480 minutes as compared to unmodified TiO2 which ca. 64.77% COD remained at same irradiation time. Also, the immobilized Ag doped TiO2 is durable with sustain of its photocatalytic performance which able to perform the same photocatalytic activities up to 10 cycles.