Effect of ore type on the leaching and biosorption characteristics of lead from waste cupels using spent tea leaves (camellia sinensis)
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Date
2019-06
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KNUST
Abstract
Waste cupel samples from two commercial gold fire assay laboratories in Ghana were sampled and characterized. The selection of the fire assay laboratories was based on the type of ore being processed. Comparative study of the effect of ore type (oxide and sulphide) on the leaching and biosorption characteristics of lead from waste cupels using spent tea leaves (Camellia sinensis) was investigated. Both laboratories use magnesia (MgO) cupels. Waste cupel samples were collected, pulverised and characterized prior to acid digestion. The mineralogical and chemical compositions were determined using X-ray Diffraction and Inductively Coupled Plasma Optical Emission Spectroscopy / Mass Spectroscopy, respectively. Leachates from the waste cupels were contacted with spent tea leaves and the biosorption efficiency and specific metal uptake determined. Results show that lead concentrations in waste cupels from oxide ore (CWO) increased as particle sizes increased whilst lead concentration from sulphide ore (CWS) decreased with increased particle sizes. The biosorption efficiency of lead was higher in CWO leachate ( > 99 %) than in CWS leachate ( < 98 %). For a given biomass concentration, CWO recorded a higher specific metal uptake as compared to CWS. The specific metal uptake in both samples were affected by the volume of leachate and lead concentration in leachate. In both samples, the adsorption isotherms fitted well in Langmuir model. The results from this study indicate that spent tea leaves can be used as an adsorbent to render waste cupels non-toxic before disposal.
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A thesis submitted to the Department of Materials Engineering, in partial fulfilment of the requirements for the degree of Master of Philosophy Environmental Resources Management