Encapsulating TiO2 into Polyvinyl Alcohol Coated Polyacrylonitrile Composite Beads for the Effective Removal of Methylene Blue

Abstract

In this work, novel nanocomposite beads based on polyvinyl alcohol (PVA) coated polyacrylonitrile (PAN) with encapsulation of TiO2 nanoparticles (PPT) were developed successfully via a novel green synthetic method and its methylene blue (MB) removal ability by adsorption was also investigated. As-prepared nanocomposite beads were characterized by different techniques such as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). TiO2 nanoparticles were encapsulated into the composite beads to endow the composite beads with photocatalytic ability and enhance its adsorption capacity for MB. Batch experiments with several variables such as TiO2 nanoparticle content, pH of the solution, contact time and initial MB concentration were carried out. The adsorption kinetic study revealed that the MB adsorption process agreed well with pseudo-second order model and showed 3-stage intraparticle diffusion model. The adsorption isotherm study indicated that the MB adsorption process could also be better described by Langmuir isotherm model. According to Langmuir isotherm equation, the maximum adsorption capacity and removal rate for MB was 242.13 mg g-1 and 98.4%, respectively. Moreover, the stability and reusability of as-prepared PPT beads were further explored and results demonstrated that PPT could be reused at least five times with negligible loss of sorption capacity and removal rate. Therefore, PPT is expected to be a potential candidate for effluents treatment.