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

Abstract

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 130mg/L (pH=3.0, 298K) the adsorption capacity of DBP by PP-g-CaSiO3@SiO2 reached 54.8mg/g, and the adsorption equilibrium time was two hours. The large surface area and SiOH 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 3.54×103L/mol, −66.2kJ/mol and 0.154kJ/(K*mol), respectively. The Gibbs’ energy change during the binding process was −20.24kJ/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.