Farshid Kazemi - Department of Applied Chemistry, Mashhad Branch, Islamic Azad University, Mashhad, Iran
Hasan Ali Zamani - Department of Applied Chemistry, Mashhad Branch, Islamic Azad University, Mashhad, Iran
Mohamad Reza Abedi - Department of Applied Chemistry, Quchan Branch, Islamic Azad University, Quchan, Iran
Mahmoud Ebrahimi - Department of Applied Chemistry, Mashhad Branch, Islamic Azad University, Mashhad, Iran

Methadone is a synthetic drug utilized to manage chronic pain and treat opioid maintenance. The drug enters water bodies as a contaminant due to its widespread use in various communities, which is usually not removed by wastewater treatment plants. Therefore, a photodegradation procedure was developed to degrade and remove methadone in water samples. A hydrothermal strategy was applied to prepare three photocatalysts based on Cr۲O۳ nanoparticles, a polyoxometalate (phosphotungstic acid), and a hybrid material (Cr۲O۳ nanoparticles encapsulating phosphotungstic acid). The effective factors, such as methadone concentration, pH, photocatalyst amount, and H۲O۲ concentration, in the photodegradation method for each catalyst were optimized by an experimental design using a central composite design. Under the optimum conditions, the kinetic model and maximum photodegradation efficiency of the process for each catalyst were studied to compare their ability for methadone degradation. The maximum photodegradation efficiencies for methadone degradation using phosphotungstic acid and Cr۲O۳ nanoparticles were ۸۲.۰۰ and ۷۷.۱۸% for ۱۲۰ min. In comparison, the maximum photodegradation efficiency in the presence of Cr۲O۳ nanoparticles encapsulating phosphotungstic acid was ۹۰.۱۱% for ۱۰۰ min. The results indicated the new hybrid material prepared from encapsulating phosphotungstic acid with Cr۲O۳ nanoparticles, leading to a proper increase in the methadone degradation and reducing the degradation time significantly. 

Methadone, Cr۲O۳, Hydrothermal Synthesis, Hybrid material