Removal of Rh 6G and DB 71 Dyes from Aqueous Solution with High Efficiency via Adsorption on Mesoporous Silica Nanoparticles

Abstract

Removing cationic and ionic dyes from aqueous solutions has been studied using mesoporous silica. Cetyltrimethylammonium bromide (CTAB) was used as a template and sodium silicate, a low-cost precursor of silica, was used in the Sol-gel process. The N₂ adsorption–desorption isotherms; TEM, XRD, and SEM were used to analyze the silica particles. The findings demonstrate that mesoporous silica (MPS) particles in the nano range (40-80 nm) have the form of flower particles, with an average pore width of 3.44 nm, a precise surface area of 423.52 m²g-¹, and a pore volume of 0.5677 cm3/g. These particles may effectively adsorb dyes. The Langmuir, Freundlich, and Timken models of adsorption suited the adsorption equilibrium data, and the best-fitting isotherm model was determined using the linear regression coefficient R². A variety of thermodynamic parameters have also been assessed, including enthalpy, entropy, and Gibb's free energy of the ongoing process of adsorption. The exothermic adsorption process was spontaneous, according to the thermodynamic data. The two dyes adsorb according to pseudo first order rate kinetics for the DB71 dye and pseudo second order rate kinetics for the Rh 6G dye. Batch approach was used for the kinetic data.