Synthesis of a Poly(glycerol-sulfur) Network as a Sustainable Adsorbent for Positively Charged Dyes from Aqueous Solutions

Abstract

Textile and industrial dyes, which are among the most prominent organic compounds, pose a range of health risks and require efficient treatment before being released into the environment. In this study, a polymeric network was synthesized through the cationic ring-opening copolymerization of glycerol and elemental sulfur, both byproducts of the biodiesel and oil industries. This network was then used as an adsorbent for the cationic dyes. The structure and composition of the synthesized poly(glycerol-sulfur) (PG-S) were characterized by using various spectroscopy methods along with elemental and thermal analysis. PG-S exhibited thermal stability up to 450 °C, an average pore size of 4.6 nm, and a surface area of 88.7 m2/g. Solid-state NMR spectra revealed a distinct C–S signal, which confirmed the successful synthesis of the composite. PG-S demonstrated excellent potential for removing industrial dyes from contaminated water. We investigated various parameters, including initial dye concentration, adsorption time, pH, adsorbent quantity and size, and temperature, to better understand the dye adsorption mechanism. The results showed that PG-S efficiently removed Janus Green (JG) and Crystal Violet (CV) from water in a selective manner. The maximum adsorption capacities were observed within the pH range of 6–12, with values of 267 mg g–1 for JG and 226 mg g–1 for CV. These values remained unchanged after 10 cycles of recycling. Given its straightforward synthesis and exceptional physicochemical properties, such as a high adsorption capacity, this polymeric network is a promising candidate for dye removal and water treatment applications.