Iranian Journal of Catalysis (IJC) Preparation of ZnO nanocatalyst supported on todorokite and photocatalytic efficiency in the reduction of chromium (VI) pollutant from aqueous solution Volume 9 (2019) Issue 3, September 2019 2024 02 03 Preparation of ZnO nanocatalyst supported on todorokite and photocatalytic efficiency in the reduction of chromium (VI) pollutant from aqueous solution EN Maryam Sabonian Department of Chemistry, Arak Branch, Islamic Azad University, Arak, Iran. Kazem Mahanpoor Department of Chemistry, Arak Branch, Islamic Azad University, Arak, Iran Journal Article 2024 02 03 In this research, a new effective photocatalyst was prepared by supporting ZnO on a Todorokite (TD). This catalyst was characterized by employing scanning electron microscopy (SEM-EDX) and X-Ray Diffraction (XRD) patterns. The optical properties of the samples were measured by diffuse reflectance spectroscopy (DRS). The purpose of using the ZnO/TD as a photocatalyst was to reduction Cr(VI), which is a pollutant in water. Experiments were carried out under different operating conditions including an initial concentration of Cr(VI), photocatalyst amounts and pH values. To optimize processes and obtain a mathematical model, the researcher used a full factorial design (with three factors at three levels). The optimal conditions were determined where the amount of photocatalyst= 200 mg L-1, pH= 2 and concentration of Cr(VI)= 15 ppm. The reduction efficiency in an optimal condition was 97.73%. The experimental results showed that kinetic was the first order and k= 0.1489 min–1.