Adsorption-photodegradation performance of Silver Titanate for Methylene blue removal: Kinetics, thermodynamics and isotherm studies

Abstract

Silver titanate (AgTO) was synthesized via an ion-exchange reaction between sodium titanate and silver nitrate. This study investigates the efficiency of AgTO in the combined adsorption-photodegradation process for removing Methylene Blue (MB). The synthesized material was characterized using FTIR, XRD, SEM, and EDX techniques. Batch adsorption experiments were conducted to assess the effects of AgTO dosage (0.1–1.0 g/L), initial MB concentration (5–20 mg/L), pH (3–11), and temperature (313–333 K). The highest MB removal efficiency (90 %) was achieved at 313 K, pH 3, and an initial MB concentration of 5 mg/L. The photocatalytic performance of AgTO was further evaluated under an 18-Watt UV light source, confirming its effectiveness in MB degradation. Adsorption followed pseudo-second-order (PSO) kinetics, while photodegradation adhered to first-order (FO) kinetics. Thermodynamic analysis indicated that both adsorption and photodegradation were endothermic processes. The Langmuir isotherm model, with a maximum adsorption capacity of 5.24 mg/g, provided the best fit for the adsorption data. Overall, as-prepared AgTO exhibited dual-functionality in a combined adsorption-photodegradation system for MB removal, revealing its high efficiency, kinetics, and thermodynamic feasibility, thereby establishing AgTO as a promising candidate for wastewater treatment.