Study of Methylene Blue from Water Solution Adsorption onto Mesoporous Silica (SiO₂) Synthesised from Clay via a Mineral Sol

Abstract

Background: Methylene blue (BM), whose toxic effects are not immediately apparent, can, in the long term, cause damage to the cardiovascular, central nervous, dermatological, gastrointestinal, genitourinary, and haematological systems in humans. It is therefore essential to eliminate this dye from wastewater.  Aims: The present study aims to investigate the elimination of methylene blue from water solution by adsorption on mesoporous silica. Study Design: This study was conducted using a batch method for the treatment of aqueous methylene blue solution through the adsorption technique. Place and Duration of Study: Département de Chimie, Université de N’Djamena, from August 2025 to October 2025. Methodology: This study aims to remove a synthetic dye, specifically methylene blue, using mesoporous silica (nanometer-sized amorphous silica) synthesised via a colloidal route. The adsorption technique is implemented by examining the influence of pH, temperature, and dye concentration under various experimental conditions. During the experiments, a fixed mass of adsorbent was introduced into different beakers containing 50 mL of the colored solution and then subjected to continuous stirring for 180 minutes at 25 °C. The effects of the experimental parameters on the adsorption process were also investigated in this work. Results: Synthesised SiO2 has a pHpzc of 7,57. An optimal pH of 8 was determined at 25 °C, resulting in 99.079% dye removal. Equilibrium was reached after 10 minutes of contact with a removal rate of 99.63%. With a mass of 40 mg of the adsorbent, 99.65% of the dye was removed. The Langmuir isotherm accurately describes the experimental data, while the pseudo-second-order kinetic model more precisely describes the adsorption behaviour. Conclusion: This mesoporous silica (SiO2) synthesised via a Mineral Sol is a promising candidate for the remediation of wastewater pollution.