Congo red removal from aqueous solution via biosorption onto Trametes trogii-loaded poly(hydroxyethyl methacrylate) cryogel

In this study, Trametes trogii-loaded poly(2- hydroxyethyl methacrylate) cryogel (Tt-PHEMA) was prepared and used as a biosorbent to remove Congo Red (CR), from aqueous solutions. The biomass and Tt-PHEMA cryogel were characterized with scanning electron microscopy and Fourier Transform infrared spectroscopy. Macroporosity degree (%) and swelling ratio (%) of the Tt-PHEMA cryogel were determined as 78.3% and 61.04%, respectively. The effect of loaded biomass amount, pH, initial CR concentration, temperature, and contact time were investigated detailedly. The maximum biosorption capacity of Tt-PHEMA cryogel was 156.71 ± 1.22 mg g⁻¹ at pH 6.0 at 45°C. Biosorption capacity was increased from 125.92 ± 1.524 mg g⁻¹ to 156.71 ± 1.22 mg g⁻¹ with increasing temperature from 25 to 45°C, demonstrating that the biosorption process was endothermic. The biosorption data were well fitted to the Freundlich isotherm and pseudo-second-order kinetic models. The negative Gibbs free energy change values showed favorable biosorption. The Tt-PHEMA cryogel was easily regenerated with ethanol and used repeatedly five times without a significant change in the biosorption capacity. As a result, Trametes trogii-loaded PHEMA cryogel has an application potential for CR removal from wastewater, taking advantage of interconnected macroporous structure cryogels.