Characterization of biomass ash/char and use for treatment of sulphur and selenium oxy-anions

Range, Bhagya Maheshi Kumari (2014) Characterization of biomass ash/char and use for treatment of sulphur and selenium oxy-anions. Masters thesis, Memorial University of Newfoundland.

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Abstract

This thesis presents the chararacteristics of eight biomass ash/char samples obtained from three pulp and paper mills in Canada. It also discusses the results from the adsorption studies conducted using these biomass ash/char to remove sulfur and selenium oxy-anions from mining effluent water streams such Acid Mine Drainage (AMD). Chemical, physical, thermal and structural characteristics investigated in this study confirmed the suitability of using these ash/char as adsorbents in waste water treatment applications. Batch equilibrium adsorption experiments were performed using individual solutions of thiosulphate, trithionate, tetrathionate, selenite and selenate by varying different parameters (ash type, initial pH, adsorbent dose, temperature). Maximum adsorption efficiency and adsorption capacity values obtained for sulphur oxy-anions were 35.6% and 14.24 mg/g of CBM-W biomass char. For selenium oxy-anions, the maximum adsorption efficiency and adsorption capacity values were at 15.2% and 0.211 mg/g of CLM2 biomass ash. Thermodynamic parameters were calculated and the data were fitted using Langmuir and Freundlich isotherm equations. The results confirmed that sulphur and selenium oxy-anions have considerable affinity towards biomass ash/char. However, further characterization of spent biomass ash/char needs to be carried out in order to identify the adsorption mechanism and also to modify biomass ash/char chemically or thermally to yield high removal efficiencies. Therefore, this study substantially contributes in assessing the feasibility of using one waste stream to treat another waste stream in the field of sustainable waste management.

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