Kinetics and adsorption assessment of 1, 4-dioxane from aqueous solution by thiol and sulfonic acid functionalized titanosilicate

In this work, thiol (-SH) and sulfonic acid (-SO3H) groups post grafted on Titanosilicate (TS-SH, TS-SO3H) was successfully prepared and efficiently used for the remediation of 1, 4 dioxane from aqueous medium employing batch experiments. The non-chemical interaction between the dioxane molecules and the titanosilicate surface plays a vital role in the remediation process, and the surface porosity can signifi- cantly boost the adsorption performance. The surface area of TS is 122 m2/g and decreases to 110 and 95 m2/g for TS-SH and TS-SO3H, respectively, while the pore volume declines from 0.213 cm3/g to 0.193 and 0.184 m3/g for the same samples. The results revealed that TS-SH follows the Freundlich iso- therm (R2 = 0.9954), while TS-SO3H follows the Langmuir isotherm (R2 = 0.9963). The Langmuir removal capacity of TS-SO3H for dioxane was found to be 164 mg/g. The adsorption kinetics for dioxane fits Pseudo second-order (PSO) and intraparticle diffusion (IPD). Such models suggest that particle diffusion and columbic interactions governed the adsorption characteristics. The desorption of dioxane using low concentration of HNO3 resulted in a considerable regeneration performance. The adsorption of dioxane on TS-SH and TS-SO3H was 98%, and 96%, respectively, reduced to 55%, and 75%, after four consecutive adsorption cycles.