Sustainable removal of malachite green from wastewater using mesoporous BaTiO₃: synthesis, characterization, and adsorption performance

In this study, mesoporous barium titanate (BaTiO₃) was synthesized using a single-step solid-state reaction by blending TiO₂ and BaCO₃ followed by thermal treatment. The produced BaTiO₃ served as an effective adsorbent for the uptake of malachite green (MG) from aqueous media. The synthesized BaTiO₃ was subjected to characterization using XRD, FTIR, SEM, TEM, EDX, and BET, demonstrating the formation of a crystalline, mesoporous perovskite structure with an average crystallite size of 68.2 nm and a surface area of 28.1 m²/g. Although its surface area is moderate, BaTiO₃ had a substantial maximum adsorption capacity of 495.15 mg/g, attributable to its oxygen vacancies, electrostatic attraction, and robust chemisorption mechanisms. The effect of various experimental factors, for example, pH, initial MG concentration, adsorbent dosage, contact time, temperature, and ionic strength, on MG removal using batch adsorption experiments was investigated. Optimum MG removal was achieved at pH of 5.0, adsorbent dose of 10.0 mg, initial solution volume of 10.0 mL, contact time of 330 min., and temperature of 50 °C. Kinetic studies were consistent with pseudo-second order model and the Langmuir model provided the best description of the adsorption isotherm. Thermodynamic variables such as (ΔG°, ΔH°, and ΔS°) were determined, and it was shown that the adsorption was feasible, spontaneous, and endothermic. Effective MG removal of over 98% was demonstrated in real sample applications comprising models of industrial wastewater and water from the Nile River. The study revealed that MG could be successfully extracted from wastewater samples using BaTiO₃, which may be produced in a sustainable manner.