Abstract
Pharmaceutical compounds which enter the environment are classified as emerging pollutants. Among different drug compounds, anti-cancer drugs like methotrexate are of more concern due to their mutagenic, carcinogenic, and genotoxic properties. Therefore, the main objective of this study was to use catalytic ozonation processes (COPs) as novel advanced oxidation processes to degrade methotrexate from aqueous solutions. The calcination method was used to obtain a nitrate magnesium oxide nano-catalyst. The main variables considering the effect of single ozonation processes (SOPs) and COPs on the target pollutant were initial methotrexate concentration, contact time, solution pH, and MgO dosage. The BET results indicated that the surface area of the MgO nano-catalyst was 140.031 m2 g-1. Based on the BJH plot, the size of the MgO nano-catalyst and average pore volume were 44.5 nm and 0.4454 cm3 g-1, respectively. The weight percent of Mg and O was 61.09% and 38.91%, respectively. In acidic and alkaline pH, the degradation rate of methotrexate showed a higher increase in SOPs and COPs than at neutral pH. The degradation rate of methotrexate decreased with increasing concentration. By increasing the contact time, the degradation rate of methotrexate of both SOPs and COPs increased. Actually, the methotrexate degradation in COPs was faster than in SOPs. When using tert-butanol as a scavenger, the reduced removal efficiency in SOPs and COPs was 32% and 31%, respectively.