Intensified desulfurization of simulated crude diesel containing thiophene using ultrasound and ultraviolet irradiation

A novel desulfurization approach involving ultrasound, ultraviolet irradiation and additives (catalyst and/or oxidants) was investigated for degradation of thiophene (model sulphur compound) present in n-hexane considered as simulated crude diesel. The approaches based on ultrasonic horn also involved combination with various additives such as titanium oxide, zinc oxide, peracetic acid and hydrogen peroxide (H2O2) operated under ambient conditions. All the lab scale studies were performed under fixed condition of 100 W as power and 80% as duty cycle at 500 ml as the operating capacity. The combination of ultrasound and peracetic acid at optimum loading of 8% resulted in higher extent of desulfurization (actual value as 23.4%) compared to the desulfurization obtained using 0.3% loading of zinc oxide and 0.3% loading of titanium oxide combined with ultrasound with desulfurization extent as 13.5 and 22.5% respectively under optimized conditions. The approach of ultrasound and UV light combined with titanium oxide and hydrogen peroxide at optimized loading has also been studied. Maximum desulfurization was obtained as 99% for the combined approach of ultrasound, ultraviolet irradiation, titanium oxide at loading of 0.3 g/L and H2O2 at loading of 300 ppm. Higher degree of desulfurization with the minimum sulphur retention up to 1-2 PPM under intensified processing conditions in terms of lesser treatment time, lesser requirement of oxidants and better cost effectiveness were the main advantages of the combined approach established in the current work as compared to the conventional desulfurization approaches.