Smart solar water treatment: Sensor-informed control of solar TiO₂ photocatalysis for sustainable environmental water treatment

This study presents a solar-driven photocatalytic treatment system for decentralised water remediation evaluated under real outdoor conditions. A TiO₂-based photocatalyst operated in a 5 L compound parabolic collector (CPC) reactor was assessed using a combination of field Analytical modelation and irradiance–performance analysis. Real-time global horizontal irradiance (260–910 W m⁻²) showed a strong linear relationship with apparent degradation kinetics (R² = 0.84–0.88), demonstrating that photocatalytic activity was primarily governed by photon availability under natural sunlight. Under peak solar conditions, removals of 92 ± 4% atrazine, 86 ± 6% imidacloprid, and 79 ± 5% sulfamethoxazole were achieved within 60 min. To examine operational optimisation, treatment performance was analysed against concurrent irradiance data to identify efficient operating windows. Based on this relationship, an irradiance-gated operational strategy was estimated to increase daily pollutant throughput by approximately 32% compared with fixed-schedule operation. Analytical models using natural river water showed a 20–35% decrease in removal efficiency, attributed to increased turbidity and dissolved organic matter that attenuate light penetration and compete for reactive species. Overall, the results demonstrate the feasibility of solar CPC photocatalysis for decentralised treatment of agricultural runoff and highlight the importance of irradiance-responsive operation for improving process efficiency under variable sunlight.