Adsorption of dibutyl phthalate in aqueous solution by mesoporous calcium silicate grafted non-woven polypropylene

The purpose of this research is to synthesize mesoporous calcium silicate grafted non-woven polypropylene (PP-g-CaSiO₃@SiO₂) and to evaluate its adsorption performance for dibutyl phthalate (DBP). The results indicated that the adsorption capacity of PP-g-CaSiO₃@SiO₂ was superior to non-woven polypropylene fabric (PP) and CaSiO₃ grafted PP non-woven (PP-g-CaSiO₃). The adsorption mechanism of DBP by PP-g-CaSiO₃@SiO₂ at different pH values was investigated. When the initial concentration of DBP was 130 mg/L (pH = 3.0, 298 K) the adsorption capacity of DBP by PP-g-CaSiO₃@SiO₂ reached 54.8 mg/g, and the adsorption equilibrium time was two hours. The large surface area and Sisbnd OH groups on PP-g-CaSiO₃@SiO₂ could improve the adsorption capacity and affinity for DBP. Isothermal titration calorimetry (ITC) was used to illustrate the driving force for the adsorption of DBP to CaSiO₃@SiO₂. The binding constant K, binding enthalpy (ΔH) and binding entropy (ΔS) between DBP and CaSiO₃@SiO₂ were obtained to be 3.54 × 10³ L/mol, -66.2 kJ/mol and 0.154 kJ/(K*mol), respectively. The Gibbs' energy change during the binding process was -20.24 kJ/mol, indicating that the adsorption process was thermodynamically favorable. Freundlich model was more suitable to describe the adsorption of DBP onto PP-g-CaSiO₃@SiO₂. Lower temperature and lower pH can promote the adsorption of DBP. PP-g-CaSiO₃@SiO₂ can be recycled for reuse. It is promising to be used as a good adsorption material to remove DBP or other contaminants from aqueous solutions.