Enhanced dye adsorption on CTAB directed mesoporous silica derived from wheat husk ash

Abstract

In this work, mesoporous silica particles were successfully synthesized from wheat husk ash via a precipitation method, utilizing cetyltrimethylammonium bromide (CTAB) as a structure-directing agent. The synthesized materials were characterized using XRD, FE-SEM, N₂ physisorption, zeta potential, and FTIR analyses. The introduction of CTAB during synthesis led to a significant enhancement in surface area (880.8 vs. 267.4 m²/g) and pore volume (0.879 vs. 0.194 cm³/g) compared to the template-free silica, while both adsorbents exhibited strongly negative zeta potentials confirming high colloidal stability. The equilibrium adsorption behavior of methylene blue was best described by the Langmuir isotherm, confirming monolayer adsorption with a maximum capacity (q_max) of 110.3 mg/g for CT-MPSi, and thermodynamic analysis indicated spontaneous adsorption (ΔG° = −26.6 kJ mol^− 1). FTIR analysis confirmed MB retention on both surfaces, with markedly stronger dye uptake on CT-MPSi, and the material retained 81.7% removal efficiency after five consecutive cycles. These results show that CTAB-templated mesoporous silica derived from wheat husk ash can serve as a viable and low-cost adsorbent for cationic dye removal from aqueous media.