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Gasification study of a single Indian sub-bituminous coal char particle is carried out in the temperature range of 880−910 °C in a pure CO 2 atmosphere. Two temperatures, 900 and 800 °C, are used for char preparation, and the char obtained at higher temperature is found to be more reactive. A fully transient nonisothermal model is developed incorporating the reaction kinetics along with transport limitations. Spatial and temporal variation of thermo-physical properties like thermal conductivity, diffusivity, and density of the gas mixture and variable specific pore surface area and accessible porosity are included in the model. The model computation shows that the combined kinetics and heat transfer model is more effective to predict the experimental findings of the present authors and that reported in the literature. The simulation study is carried out to assess the effect of reaction temperature, particle size, and char reactivity on the particle temperature, conversion, gasification rate, and CO and CO 2 mass fractions within the porous volume of the particle.

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Fluoride contamination in groundwater is now becoming a global concern. In the present study, removal of fluoride using dry biomass (DBM) of a micro-algal consortium of Chlorococcum infusionum and Leptolyngbya foveolaurum, collected from a coke-oven effluent treatment plant, Durgapur, India, has been investigated. The large volume of algal bloom in the industrial effluent has created serious disposal issues and caused severe environmental concerns. A biosorption technique has been carried out to valorize the waste algae biomass into a potential adsorbent. Response Surface Methodology (RSM) is used to model and optimize fluoride removal. Maximum fluoride removal (72%) is obtained at pH 4, 5 mg/L initial fluoride concentration, 0.5 g/L adsorbent dose (AD), and 25 °C temperature during one-factor-at-a-time (OFAT) analysis. The optimum condition of removal as specified by RSM is - initial concentration of fluoride: 30 mg/L, pH: 4.5, AD: 3.5 g/L and temperature: 30 °C. FESEM-EDX, FTIR and BET isotherm studies are done to characterize raw and fluoride treated biomass. Lagergren first order kinetic model and Freundlich isotherm model, are found to analyze best kinetic and equilibrium data, respectively. Adsorption capacity of DBM has been found to be 34.36 mg/g. The kinetics of fluoride removal have been well described by COMSOL Multiphysics.

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