Sintesis Satu Langkah Hibrida TIO2/Pumice Menggunakan Metode Hidrotermal Untuk Penghilangan Metilen Biru

Abstract

Methylene blue (MB) is a synthetic dye commonly found in textile wastewater that is resistant to biological degradation, posing risks to aquatic ecosystems and human health. Titanium dioxide (TiO2) is a promising photocatalyst for MB degradation, but its application in suspended nanoparticle form faces separation and light-exposure limitations. This study addresses these issues by immobilizing TiO2 on pumice, a porous and buoyant volcanic material, through a one-step in situ hydrothermal method, eliminating the need for separate synthesis and coating stages used in previous approaches. TiO2/pumice composites were synthesized with pumice mass variations of 5, 10, 15, and 20 g, then characterized using SEM-EDX and XRD, and evaluated for MB removal activity, dosage optimization, and reusability. SEM-EDX confirmed a substantial increase in Ti content after hydrothermal treatment, from 0.42 wt% in raw pumice to a range of 3.74–8.62 wt% across composite samples, with a relatively uniform Ti distribution. The TP-15 sample (15 g pumice) exhibited the highest MB removal efficiency of 60.79% and the highest pseudo-first-order rate constant of 0.00919 min⁻¹ after 105 minutes of UV irradiation, establishing it as the optimum composition. Dosage optimization on TP-15 revealed maximum performance at 10 g/L (95.14% removal), while excessive dosing reduced efficiency due to light-scattering effects. Reusability testing showed a progressive decline in photocatalytic performance across five cycles, attributed to mechanical erosion and mass loss of the composite. XRD analysis confirmed the presence of anatase-phase TiO2 alongside a naturally occurring α-Fe (ferrite) phase from the pumice, suggesting a potential Schottky junction that may enhance charge separation. These findings demonstrate that the one-step hydrothermal method is a viable and simplified route for producing TiO2/pumice composites for water treatment applications, though improvements in mechanical stability are needed to enhance long-term reusability.