Synthesis and characterization of polymeric films composed of polyvinyl alcohol/chitosan with superior adsorption capacity for removal of Remazol Black B

Abstract

This study used chitosan with functional groups and PVA polymer with strong film-forming-mechanical properties to obtain a new adsorbent material, and the usability of membranes bearing the combined effect of these materials in dye adsorption was investigated through experimental studies. To synthesize poly(vinyl alcohol)/chitosan (PVA/Cht) membranes, 6% (g/mL) PVA solution was mixed with a chitosan solution of 4% (g/mL) in a volumetric ratio of one to one. The PVA/Cht polymer mixture was processed into membranes via solvent casting and subsequently maintained at 150 °C for an hour to promote physical cross-linking. Fourier transform infrared spectroscopy (FTIR) was used to study the structural composition of the synthesized membranes, which verified the presence of PVA and chitosan. The membrane morphology was assessed using scanning electron microscopy (SEM), while energy dispersive spectroscopy (EDS) outcomes demonstrated the presence of carbon, oxygen, and nitrogen in the membranes. Thermogravimetric (TGA) analysis was also carried out to evaluate the membranes’ thermal stability. Following this, the membranes were also tested for their ability to adsorb Remazol Black B (RBB) dye under a range of experimental conditions. Maximum adsorption occurred with membranes at low pH (at pH 2). It was observed that adsorption time reached equilibrium in 24 h. During adsorption experiments at various incubation temperatures, the dye removing efficiency of the membranes improved with rising temperatures. When adsorption was performed with membranes at different initial dye concentrations, it was observed that there was no change in the adsorption capacity of membranes after a certain dye concentration. When adsorption experiments were conducted with varying initial adsorbent quantities, at a dye concentration of 800 mg/L, pH 2, 24-h incubation, and 0.02 g of adsorbent, the membranes reached a peak dye removing of 625.51 mg/g. Membranes have very high paint removing capacity. The usability of the obtained material as a potential adsorbent was proven; further studies will be carried out to develop the materials planned to be produced and put them into practice.

Graphical Abstract

A schematic diagram of the synthesis of polymeric films composed of PVA/Cht with superior adsorption capacity for the removal of RBB dye. Created with Biorender.com.