PROTONATED SPENT MUSHROOM SUBSTRATE AS A POTENTIAL LOW-COST BIOSORBENT FOR THE REMOVAL OF REACTIVE RED 15 FROM AQUEOUS SOLUTIONS

This study aimed at determining the feasibility of using protonated spent mushroom substrate (PSMS), an abundant agricultural waste in China, as a low cost biosorbent for the removal of Reactive Red 15 (RR15) from aqueous solutions. Batch biosorption studies were conducted to evaluate the effects of pH value, biosorbent dosage, initial dye concentration and contact time on the removal of RR15. The results show that initial pH would be the most important parameter affecting RR15 biosorption, and the optimal pH was 1.2. Freundlich isotherm fitted well with the equilibium data. Kinetic studies show that biosorption of RR15 followed the pseudo-second-order kinetic model, both intraparticle diffusion and boundary layer diffusion might affect the biosorption rate. The thermodynamic analysis indicates that the biosorption process is spontaneous and exothermic. The FTIR analysis reveals that chemical functional groups (e.g., amine, phosphonate and others) on PSMS would be the active binding sites for biosorption of PSMS. These results show that PSMS could be employed is a low-cost and alternative biosorbent for the removal of RR15 from wastewater.