Optimisation, modelling and mechanism of photocatalytic degradation of sofosbuvir antiviral by TiO2 nanoparticles coupled with biological treatment

Abstract

ABSTRACT The overarching objective of this research endeavour was to develop an integrated approach to the complete removal and breakdown of the antiviral compound sofosbuvir. To accomplish this, a two-fold strategy was employed, involving a heterogeneous photocatalysis process coupled with subsequent biological treatment. Leveraging the versatile TiO2-P25 nanoparticles, a meticulous optimisation was carried out using the Box-Behnken methodology, strategically considering the interplay of three pivotal independent variables: pH, initial molecule concentration, and catalyst concentration. This optimisation aimed not only to augment the degradation of sofosbuvir but also to enhance its COD removal. The complex influence of these factors was mathematically encapsulated in a second-order polynomial equation, offering valuable insights into the process dynamics. COD removal and optimal parameters for degradation were a pH of 6.8, a catalyst dosage of 1 g L−1, and an initial molecule concentration of 0.1 mM under a 125 W high-pressure mercury lamp. The efficiency of elimination for the degradation was 100% at 120 min and for the COD removal extinguished 99.44% at 6 h. Sofosbuvir has a rapid degradation, COD removal degree is lower, which means the presence of intermediate compounds more difficult to treat by photocatalysis. Thus, the viability of implementing a link between the nanoparticles TiO2-photocatalysis as a biodegradability improvement pretreatment with the biological process has been studied as an essential activity to enhance treatment efficiency while reducing energy use and treatment times. combination of photocatalysis with a biological treatment improves the treatment. The density functional theory (DFT) approach was applied to better understand the mechanism of sofosbuvir degradation and to examine the impact of different degradation sites. Mechanism Analysis of the photoproducts and photoproduct intermediates was identified by HPLC-MS. However, a 120 min BOD5/COD ratio (COD, chemical oxygen demand; BOD, biochemical oxygen demand) of ≥0.4 results from the degradation of sofosbuvir by TiO2.