Kinetics of biodesulfurization of a high-sulfur coal

The apparent activation and deactivation energies and the corresponding frequency factors of coal desulfurization byThiobacillus ferrooxidans have been determined to be ΔE _a = 60.9 kJ,A _a = 1.45 s^-1 and ΔE_d = 178.3 kJ,A _d = 5.65×10²⁷ s^-1, respectively. The thermo-dynamic values (AG^?, ΔH ^?, and ΔS^?) of the activated complex were calculated. Kinetic parameters of the Monod equation were determined to beV _m = 55.9 mg dm^-3 h^-1 andK = 24.1% pulp density. The maximum rate of desulfurization of coal was found to beV _m = 55.7 mg dm^-3 h^-1 for the particle size. The generalized second order regression equation relating the yield of desulfurization to the leaching parameters was shown to adequately predict coal extraction data and optimum values of process variables. Tank leaching studies using optimum conditions resulted coal desulfurization about 90%. The iron hydrolysis reactions involving the formation of mono- and poly-nuclear, hydroxo- and sulfato complexes of amorphous and crystalline precipitates were discussed.