Silver adsorption on biochar produced from spent coffee grounds: validation by kinetic and isothermal modelling
Journal Publication ResearchOnline@JCUAbstract
This study investigates silver adsorption on biochar produced from pyrolysis of spent coffee grounds (SCGs). Biochars were produced from SCGs at temperatures between 500 and 1000 °C. SCG-derived biochars were then characterised by different analytical methods, such as Brunauer-Emmet-Teller (BET), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and investigated for silver removal. The results revealed that the biochar produced at 500 °C offered a maximum surface area of 40.1 m2/g with a yield of 23.48% biochar and the highest silver adsorption capacity of 49.0 mg/g with 99.9% silver removal efficiency. The morphology of adsorbed silver on biochar was determined using scanning electron microscopy–energy-dispersive spectrometry (SEM–EDS), and XRD analyses, which showed an even distribution of silver on the biochar surface. Furthermore, X-ray photoelectron spectroscopy (XPS) confirmed that part of the silver ions was reduced to form metallic silver (Ag0)/silver nanoparticles (Ag NPs) during adsorption. The kinetics and isothermal evaluation suggested that silver adsorption was dominated by the pseudo-second-order model and Langmuir isotherm, which means that silver adsorption was mainly dominated by chemisorption and monolayer on biochar surface. Overall, this study suggests that 500 °C was the most feasible pyrolysis temperature to produce SCG-derived biochar with suitable physicochemical properties that can efficiently adsorb silver species from wastewater.
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Biomass Conversion and Biorefinery
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2190-6823
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Pages Count
15
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Springer
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DOI
10.1007/s13399-022-03491-0