Semiconductor materials exhibit a great promise in the environmental cleanup within Advanced Oxidation Processes (AOPs). CaWO4 single-phase, synthesized by a high-temperature solution method, was identified by X-ray diffraction and crystallizes in the scheelite-type structure with a tetragonal symmetry. The band gap (4.56 eV) is ascribed to a Ligand Charge Transfer (LCT): O2−: 2p → W6+: 6s. Capacitance analysis revealed n-type conductivity with a flat band potential (Efb) of 0.59 VSCE. The photo-electrons possess a strong reduction potential in the conduction band (− 0.99 V), enabling the reduction of oxygen into short-lived superoxide (O2•−), responsible of the mineralization of organic matter. As application, CaWO4 was successfully assessed for the solar-driven photocatalytic degradation of Phenobarbital (Phe-B), a recalcitrant molecule. Operating parameters including light source, catalyst dose, initial Phe-B concentration (Co), pH, and catalyst support were systematically investigated. Optimal performance was obtained under UV/C irradiation with CaWO4 in suspension (200 mg/L) at Phe-B concentration (200 ppm), reaching degradation and mineralization rates of 55 and 49% respectively. Furthermore, CaWO4 exhibited enhanced photoactivity under solar irradiation up to 65% mineralization. The kinetic follows a pseudo-first-order kinetics and an apparent rate constant kapp (= 9 × 10− 3 min− 1), which confirms its feasibility for water treatment.
