| Summary: | The bi-metal biosorption of Pleurotus ostreatus spent mushroom substrate (PSMS), a novel agriculture waste from solid substrate fermentation for mushroom production, was explored in this study. The biosorption of Cu(II) and Ni(II) in bi-metal solution using PSMS were examined under batch biosorption technique. Determination of metal biosorption was evaluated through isotherm, kinetic and thermodynamic studies in order to elucidate the mechanisms of metal biosorption. Metal biosorption results were well corresponded to Langmuir and Freundlich isotherms. The maximum uptakes were 3.54 mg/g Cu(II) and 1.85 mg/g Ni(II) for bi-metal solution. However, this PSMS biosorbent has higher selectivity to Ni(II) when compared to Cu(II). The mean energy indicated that chemisorption involved in metals biosorption. Biosorption data were superbly fitted to pseudo-second-order kinetic when compared to pseudo-first-order kinetic. The results from the pseudo-second-order kinetic also implied that chemisorption plays a major role in biosorption process. Thermodynamic parameters showed that biosorption reaction was spontaneous and exothermic. Furthermore, a weaker and reversible bond formed after biosorption, which provided evidence that chemisorption is one of the mechanisms in biosorption. The ion exchange mechanism was evaluated through ICP-OES metals concentration and pH observation. In conclusion, the high metal biosorption uptake of PSMS indicates that it is a potential biosorbent for metal removal from waste streams. The findings revealed that both chemisorption and ion exchange were the two main mechanisms involved in spontaneous exothermic reversible metal biosorption process. This piece of information provides insight into application of biosorption of PSMC in real wastewater sample. © 2015 Balaban Desalination Publications. All rights reserved.
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