Abstract

Experiment was carried out in two parts to investigate the degradation profile of trimethoprim and sulphamethoxazole, antibacterial compounds in aqueous phase. In the first part of study, the effects of UV and TiO₂ on two antibiotics using the UV-water flow system (UVWFS) were examined. Obtained results revealed that trimethoprim and sulphamethoxazole pronounced 44 to 45% and 6 to 314% elevated rate of degradation in two TiO₂ doses, 0.05 and 0.1 g/l treatments with UV than only UV treatments which affords to draw a substantial conclusion that though both UV and TiO₂ have a crucial impact but the synergistic photocatalytic effects of the TiO₂ with UV attributes a rapid and higher degree of degradation of antibiotics compared to that of only UV at the same water flow rate. In this context, it may also be observed that effect of the dose of TiO₂ was very little in trimethoprim degradation but a significantly greater effects was revealed in sulphamethoxazole that indicating same number of TiO₂ molecules acted more favourably on higher number of sulphamethoxazole molecules than trimethoprim by photocatalytic activity which enhancing the rate of degradation reaction resulting in the rapid decrease of sulphamethoxazole concentration level in water. In second part of the study, three (15, 42 and 80 cc/min) water flow rates were employed using UVWFS maintaining same UV and TiO₂ dose 0.1 g/l to ascertain the effect of water flow rate in the antibiotic transformation process. The degradation efficiency in 80 cc/min water flow treatment was 113 and 61% higher in trimethoprim and 103 and 51% higher in sulphamethoxazole compared to that of 15 and 42 cc/min water flow treatments, respectively which clearly indicated that the rate of water flow is a paramount important, largely influencing the photocatalysis reaction process of TiO₂ and UV with antibiotics in water medium possibly enhancing movement velocity of their molecules. Besides it, trimethoprim degraded rapidly over sulphamethoxazole which might be inferred that higher water flow substantially increases the rate of oxidation and photocatalytic transformation of trimethoprim over sulphamethoxazole in the presence of TiO₂ and UV.

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