doiSerbia

Dissolution kinetics of South African coal fly ash and the development of a semi-empirical model to predict dissolution

Koech Lawrence (Department of Chemical Engineering, Vanderbijlpark Campus, Vaal University Of Technology, Private Bag X, Vanderbijlpark, South Africa)
Everson Ray (Department of Chemical and Minerals Engineering, Potchefstroom Campus, North West University, private Bag X, Potchefstroom, South Africa)
Neomagus Hein (Department of Chemical and Minerals Engineering, Potchefstroom Campus, North West University, private Bag X, Potchefstroom, South Africa)
Rutto Hilary (Department of Chemical Engineering, Vanderbijlpark Campus, Vaal University Of Technology, Private Bag X, Vanderbijlpark, South Africa)

Wet flue gas desulphurization (FGD) is a crucial technology which can be used to abate the emission of sulphur dioxide in coal power plants. The dissolution of coal fly ash in adipic acid is investigated by varying acid concentration (0.05-0.15M), particle size (45- 150μm), pH (5.5-7.0), temperature (318-363K) and solid to liquid ratio (5-15 wt %.) over a period of 60 minutes which is a crucial step in wet (FGD). Characterization of the sorbent was done using X-ray fluorescence (XRF), X-ray diffraction (XRD), Furrier transform infrared (FTIR), scanning electron microscope (SEM) and Branauer-Emmett-Teller (BET) surface area. BET surface area results showed an increase in the specific surface area and SEM observation indicated a porous structure was formed after dissolution. The experimental data was analyzed using the shrinking core model and the diffusion through the product layer was found to be the rate limiting step. The activation energy for the process was calculated to be 10.64kJ/mol.

Keywords: flue gas desulphurization, coal fly ash, dissolution, shrinking core model, activation energy