Bifunctional supported ionic liquid-based smart films for dyes adsorption and photodegradation

Abstract

Herein, novel bifunctional smart films containing poly(styrene-butyl acrylate-ionic liquids) (P(S-BA-ILs)) and TiO2 were first prepared by a simple cast method and then used to demonstrate a superior bifunction of adsorption/desorption for dyes due to the property of reversible wettability switching and photodegradation under ultraviolet (UV) irradiation due to the addition of TiO2. The glass transition temperature (Tg) of P(S-BA-ILs) latex was characterized using a differential scanning calorimeter (DSC). The surface properties of films (P(S-BA-ILs)-TiO2) were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), attenuated total (internal) reflection Fourier transform infrared spectroscopy (ATR-FTIR), and water contact angle (WCA) measurements. The results showed that the films displayed reversible wettability switching of hydrophobicity (124.5 ± 2°)/hydrophilicity (10.5 ± 2°) and hydrophobicity (35.1 ± 2°)/hydrophilicity (93.1 ± 2°) triggered by pH and temperature, respectively. Additionally, the films exhibited large adsorption capacities for pollutants at different pH: brilliant red (BR) (6.6 mg cm−3) at pH 1, methylene blue (MB) (12.4 mg cm−3) and phenol (1.1 g cm−3) at pH 11, and metal ions As, Mo and Sb (1.11, 1.57, and 1.25 mg cm−3) at pH 1, as well as superior reusability and excellent in situ photodegradation performance. The convenient preparation of the smart films as well as the good bifunction of adsorption and photodegradation for dyes predicts potential for application to curb water pollution.