Photocatalytic Degradation of Chloroquine Phosphate Using a Novel Biochar-Doped Titanium Dioxide: An Innovative and Efficient Treatment Approach

Abstract

Due to widespread of various epidemics, a great deal of antiviral drugs including chloroquine phosphate (CQP) were widely used in therapy. A new biochar-doping TiO₂ (BIC-Ti) was prepared by the sol–gel method and applied for efficient photocatalytic removal of CQP in aqueous solutions. The removal capacity of CQP on the composed material was up to 164.2 mg/g after 20 min UV irradiation (0.05 g/L BIC-Ti, pH = 6.6, CQP concentration = 20 mg/L). The results showed that BIC-Ti was stable with a high recovery rate (>90%) after six recycling experiments, and had much potential in practical application. According to the trapping tests, superoxide radicals (•O₂−) were crucial in CQP photodegradation. Photolytic dehalogenation and hydrolytic substitution reactions were the main reactions for CQP degradation under light conditions, and CQP was degraded to small molecular substances with low toxicity. An analysis of morphology and structure characterizations illustrated that biochar was successfully introduced onto BIC-Ti and effectively improved the product’s pore size and volume. There is an obvious increase in the specific surface area of BIC-Ti along with the formation of a larger mesoporous structure and more developed porous structure. BIC-Ti showed a typical anatase-TiO₂ structure with a relatively narrow bandgap and low PL intensity, which was helpful in absorbing a wider range of light wavelengths and reducing electron–hole recombination. This newly composed material has much potential in CQP degradation and is feasible for an innovative modification of TiO₂ photocatalyst in pharmaceutical wastewater treatment.