Methylene blue adsorption on Y-zeolite as a nano-porous adsorbent: equilibrium and kinetic studies

The elimination of dye pollutants from industrial wastewaters, notably from sectors such as textiles and dyeing, remains a pivotal aspect of pollution mitigation endeavours. This research introduces an innovative strategy employing Y zeolite as a nano-porous adsorbent for eliminating methylene blue (MB), a prevalent cationic dye. Y zeolite was synthesised via hydrothermal technique. Through methodical experimentation, the impact of temperature, contact time, concentration, pH and adsorbent quantity on removal efficiency were examined with optimal conditions achieving 93.83% MB removal. The synthesised Y zeolite underwent characterisation utilising diverse techniques, including SEM, TEM, XRD, BET, and FTIR, which elucidated the structural and chemical characteristics. The surface area and pore diameter of Y zeolite were determined to be 229.1 m2/g and 20.3 Å, respectively. Utilisation of Response Surface Methodology (RSM) using design expert software facilitated the exploration of influential parameters, such as pH, temperature, contact time, adsorbent quantity, and MB concentration. The optimal conditions of pH = 7, temperature = 43°C, contact time = 85 min, adsorbent dosage = 0.5 g/L, and initial concentration = 30 ppm were obtained. Furthermore, reusability and durability of Y zeolite through multiple cycles of MB adsorption was assessed, revealing a retained efficiency of ~ 70% after 5 consecutive cycles. Kinetic studies confirmed pseudo-2nd-order model, emphasising chemisorption as the rate-limiting step. Equilibrium data fitting to the Langmuir isotherm highlighted the homogeneity of active adsorption sites on the zeolite surface, emphasising a high adsorption capacity. In conclusion, this study offers a promising solution for the removal of MB from aqueous solutions using Y zeolite as a nano-porous adsorbent. The findings underscore the importance of zeolite's porosity and surface characteristics in enhancing adsorption efficiency, providing valuable insights for future applications in water treatment and environmental remediation efforts. This research showed that Y Zeolite is effective, low cost, eco-friendly, and can be regenerated as an adsorbent to eliminate MB from aqueous systems.