Torrefaction, is a pretreatment process in the conversion of various biomass feedstocks into an efficient solid fuel. In the present research, rice husk was torrefied at 200°C, 250°C, and 300°C for 10, 30, 90, and 150 minutes under a non-oxidative environment. The energy yield and mass yield of torrefied solid residues ranged from 51.3% to 96.8%, and 49.1% to 95.1%, respectively, under torrefaction conditions. Increasing the residence time and temperature of thermal treatment causes a rise in carbon content from 32.45% to 48.5%, and raises the calorific value from 16.48 MJ/kg to 19.82 MJ/kg. The torrefaction process also reduced the swelling tendency of the biomass in water from its initial value of 308% to 92% only. Various other characterizations including Fourier transform infrared radiation, thermogravimetric analysis (TGA) and scanning electron microscopy were performed to analyze the structural and textural aspects of torrefied biomass. The TGA and derivative thermogravimetric analysis curves indicated that torrefaction affected the hemicellulose fraction of biomass significantly. The surface morphology of thermolyzed samples revealed the rupture of the surface induced by the torrefaction process. Overall, the torrefaction process has not only improved the fuel characteristics of the rice husk but also enhanced its hydrophobicity.
The potential of Paspalum notatum grass waste to adsorb Rhodamine B dye from aqueous phase is reported in this research. The grass waste was activated and characterized through various techniques to analyze the chemical (FTIR), morphological (SEMEDX), and thermal (TGA) changes incorporated through the activation process. The pollutant removal efficiency of the raw and modified adsorbents was studied by varying different process parameters in a batch process. The maximum capacity of adsorption which was observed for grass waste and activated grass waste was 54 mg g–1 and 72.4 mg g–1 respectively. Among the various kinetic models, the pseudo-second order model gives the best regression results. However, the intraparticle diffusion-adsorption model showed that the diffusion within pores controlled the adsorption rate. Thermodynamic analysis of this process revealed that Rhodamine B adsorption was endothermic and spontaneous in nature. The results of this study show that grass waste has the potential to be used as an adsorbent for the treatment of colored water.
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Energy generation from biomass presents some serious problems like slagging, fouling and corrosion of boilers.To address these problems, demineralization of biomass is performed using different leaching agents. This study is focused on determining the infl uence of leaching agents and leaching time on the physiochemical structure of rice husk during demineralization. Dilute (5% wt) solutions of HCl and H 2 SO 4 were used for the demineralization of rice husk separately with leaching time of 15, 60 and 120 minutes. It is shown that H 2 SO 4 exhibited higher removal of alkali and alkaline earth metals (AAEM) comparatively as depicted by the 34.2% decrease in ash content along with an increase of 7.10% in the heating value. The acid has been seen to induce more notable changes in physiochemical structure as depicted by the FTIR spectra and SEM micrographs. The thermal degradation behavior of the demineralized rice husk has also been reported.Keywords: demineralization, leaching agent, physiochemical structure, alkali and alkaline earth metals, thermal degradation. PRACTICAL APPLICATIONDue to depletion in fossil fuels reserves, increase in their price, greenhouse effect and environmental pollution, the current challenge to world is to reduce its dependence on fossil fuel by developing sustainable and renewable energy supply. Energy from biomass accounts for the largest renewable energy in the world 1 . Biomass is a lignocellulosic material mainly consisting of cellulose, hemicellulose, lignin, ash and extractives 2 . One important feature of biomass is that it contains alkali and alkaline earth metals (AAEM) such as potassium, sodium, magnesium, calcium, iron etc. 3 AAEM are the main inorganic content of biomass. They are generally present less than 1% and may go up to 15% depending on the biomass type 4 . High AAEM content in biomass leads to slagging and fouling of heat exchanger in the high temperature conversion system. Slagging and fouling is the deposition of ash on the heat transfer surface forming an insulating layer. This layer reduces the heat transfer as well as causes corrosion and erosion problems. This condition puts the threat on the safe operation of the thermal system and also increases the cost of operation and maintenance. The main contributors in slagging and fouling are potassium and sodium which lower the melting point of ash resulting in ash deposition on heat transfer surface 5-7 .Demineralization of biomass has demonstrated to be an effective process for reducing the slagging and fouling nature of it by reducing AAEM content and improving its fuel properties for high temperature processes. Leaching agents (water and different acids) are used to demineralize the biomass in different studies 2, 8-11 . Jiang 2013 17 et al. used deionized water, acetic acid, hydrochloric acid, sulphuric acid, nitric acid and prthophosphoric acid. It was found that sulphuric acid and nitric acid were able to remove more AAEM than other leaching agents. Asadieraghi et al. 2014 15 demineralized palm oil biomasses w...
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