Photodegradation of naphthalene by using binary TiO2/CuO and WO3/CuO catalysts

Abstract

Naphthalene is one of polycyclic aromatic hydrocarbons (PAHs) compounds which have been identified as carcinogenic. It is commonly used in industry and domestic. Therefore, it can cause environmental pollution and must be treated. One of the promising methods to remove this pollutant from waste water is by using photocatalyst since it can degrade the pollutant without producing toxic by-products. In this research, two types of photocatalysts namely TiO2/CuO and WO3/CuO were prepared with different mass ratio of co-catalyst and it was calcined at various temperatures. TiO2 was prepared by sol-gel method while WO3 by aging amorphous peroxo-tungstic acid. The characterizations of the prepared catalysts were done by XRD, FESEM and BET surface area analyzer. XRD patterns revealed that TiO2/CuO calcined at 450 °C and 650 °C consists of single phase anatase and rutile respectively while TiO2/CuO calcined at 550 °C consist of a mixture of anatase and rutile. XRD patterns for WO3/CuO catalyst indicated that the catalyst consist of single phase of WO3. FESEM micrographs showed TiO2/CuO particles were packed loosely compared to WO3/CuO particles which were small and packed closely. BET analysis discovered that WO3/CuO catalyst has larger surface area than TiO2/CuO catalyst. The influence of pH, photocatalyst loading and the uses of different light radiation sources were studied. The reaction was monitored by UV-Vis spectrophotometer. Photocatalytic reaction performed best in neutral medium irradiated with UV light. The optimum mass percent of co-catalyst for both photocatalysts were 10% and the calcination temperature for WO3/CuO and TiO2/CuO photocatalysts was 650 °C and 550 °C respectively. The result indicated that the percentage of photodegradation for WO3/CuO and TiO2/CuO in neutral environment was 88.60% and 63.55% respectively. TiO2/CuO removed 11.01% and 33.60% of pollutant in basic and acidic environment respectively. WO3/CuO degraded 48.03% of pollutant in acidic environment while in basic environment it degraded 46.32% of pollutant. The optimum photocatalyst loading was 0.2 g for both photocatalysts. 0.2 g of WO3/CuO (90:10 650 °C) degraded 93.23% of pollutant while 0.2 g of TiO2/CuO (90:10 450 °C) removed 60.9 % of it.