Journal Article

Enhanced photocatalytic degradation of organic pollutants using a TiO 2 -clay nanocomposite in a rotary photoreactor with experimental and theoretical insights

Dorraji, Mir Saeed Seyed, Rasoulifard, Mohammad Hossein, Saeedi, Seyedeh Narges, Douroudgari, Hamed, Sehati, Negar

2025

Overview

Water pollution from synthetic dyes poses a serious environmental challenge due to their persistence, toxicity, and resistance to conventional treatment methods. To address this issue, we designed a novel rotary photoreactor employing a titanium dioxide-clay (TiO -clay) nanocomposite immobilized with silicone adhesive for efficient photocatalytic degradation. The optimized TiO -clay composite (TiO /clay = 70:30) exhibited an enhanced BET surface area of 65.35 m /g compared to 52.12 m /g for pure TiO . The point of zero charge (PZC) was determined to be pH 5.8, favoring adsorption of the cationic BR46 dye under near-neutral pH conditions. Under optimal operating parameters-20 mg/L initial dye concentration, 5.5 rpm rotation speed, and 90 min of UV exposure-the system achieved 98% dye removal and 92% total organic carbon (TOC) reduction. Kinetic analysis confirmed a pseudo-first-order model (R > 0.97) with an apparent rate constant of 0.0158 min . Radical scavenger experiments identified hydroxyl radicals (OH ) as the primary oxidative species, consistent with Density Functional Theory (DFT) predictions. GC-MS analysis further verified the degradation of BR46 into non-toxic intermediates. The TiO -clay nanocomposite demonstrated excellent stability and reusability, maintaining > 90% efficiency after six cycles. These findings underline the potential of the TiO -clay rotary photoreactor as a robust and sustainable technology for advanced wastewater treatment.