Thermodynamic Study Of The Adsorption Performance Of Spent Coffee Beans For The Removal Of Cadmium From Coal Tailing Leachates

摘要

In this study spent coffee beans were transformed into biochar using a hydrothermal method where after it was pre-treated through surfactant impregnation to enhance its adsorption capacity. The non-treated and pre-treated biochars were characterized using FTIR spectroscopy analysis, which revealed a successful preparation of biochar with the potential for adsorption. The adsorption potential and mechanism was predicted using thermodynamic study.The adsorption of cadmium on the pre-treated (PT) biochar was found to occur spontaneously while it was the case for the non-treated (NT) biochar the adsorption reaction was not thermodynamically favourable. For both adsorbents, the adsorption of the cadmium was endothermic in nature due to the large positive enthalpy values, confirming that the adsorption of cadmium on NT biochar and PT biochar occurred through a chemisorption mechanism. Although the high concentrations of metals in the coal leachate resulted in competition for binding sites at the surface of adsorbent, relatively high adsorption capacity was achieved for the removal of cadmium from the coal leachate.It could be therefore concluded that the temperature change substantially influences the adsorption behaviour and capacity of the prepared adsorbents.