Removal of Rhodamine 6G from wastewater using solar irradiations in the presence of different additives

The present work investigates the intensification aspects for the solar-induced photocatalytic degradation of basic dye Rhodamine 6G (Rh 6G) using different additives. The effect of basic operating parameters as pH and initial concentration has been investigated initially followed by studies related to understanding the effect of different additives and deciphering the controlling mechanism for intensification of degradation. The effect of catalysts such as TiO2, CuO and CaO as well as process intensifying additives such as FeSO4 and CuSO4 over the loading range of 1.5–4.5 g/L has been investigated. Among the different additives investigated in the work, TiO2 was observed to give maximum effectiveness for process intensification. The effect of radical scavengers such as methanol (CH3OH), n-butanol (n-C4H9OH) and Na2CO3 has also been investigated to elucidate whether the free radical attack is the controlling mechanism of degradation. The extent of degradation was significantly affected at higher loadings of the radical scavengers confirming the major role of hydroxyl radicals in deciding the extent of degradation. Overall, it has been observed that maximum degradation as 96.5% was obtained under optimal conditions of pH as 12.5 and initial concentration of 10 ppm using the photocatalytic approach based on TiO2 as the catalyst and CuSO4 as additive.