Simultaneous and selective removal of diclofenac and ibuprofen from aqueous matrices by a hybrid TiO2-dual-template molecularly imprinted polymer

Abstract

ABSTRACT Dual-template molecularly imprinted polymer based on TiO2 nanoparticles (NPS) (TiO2-MIP) was synthesised by surface molecularly imprinted method to achieve the simultaneous and selective removal of diclofenac and ibuprofen in aqueous media. The characterisation results of Fourier Transformed Infrared spectroscopy (FTIR), X-ray Diffractometry (XRD), Brunauer, Emmett and Teller (BET) and Field Emission Scanning Electron Microscopy (FE-SEM) revealed the successful imprinting process on the surface of titania. The effects of operating parameters including pH, initial concentration of target pollutants and dosage of nanocomposite were first investigated. Then, TiO2-MIP nanocomposites were prepared at different TiO2 NPS to imprinted polymer mass ratios, and the optimal value was determined. The best treatment performance was obtained at pH = 4, 10 mg/L of target pollutants, 1 g/L of the nanocomposite, and 1:4 mass ratio, in which the simultaneous and selective removal efficiency of diclofenac and ibuprofen was 86.6% and 75.0%, respectively. The adsorption capacity of synthesised TiO2-MIP nanocomposites for DCF and IBP was 5.22 and 4.38 mg/g, respectively. The pseudo-second-order model (R2 ≥ 0.99) and Langmuir isotherm model (R2 = 0.99) demonstrated the best fitting with experimental data. The adsorption capacity, photodegradation activity, selectivity and reusability of polymeric nanocomposite were also studied. The results revealed that the synthesised TiO2-MIP nanocomposite had higher adsorption capacity, enhanced photodegradation performance and better selectivity for target pollutants than non-imprinted TiO2 nanocomposite. The results further showed that the selection factor of TiO2-MIP for diclofenac and ibuprofen was 5.4 and 3.8 times of the competitive pollutant, respectively, indicating stronger and more specific interactions for the target molecules. The brilliant adsorption and photodegradation performance, simultaneous removal of contaminants, good stability and selectivity towards target pollutants in the presence of competitive compounds are the advantages of the as-prepared TiO2-MIP nanocomposite. Thus, a hybrid TiO2-molecularly imprinted polymer can play an influential role in the treatment of persistent environmental insults in complex aquatic environments.