| 1. |
- Schwebel, Georg, 1983, et al.
(författare)
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Apparent kinetics derived from fluidized bed experiments for Norwegian ilmenite as oxygen carrier
- 2014
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-3437 .- 2213-2929. ; 2:2, s. 1131-1141
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Tidskriftsartikel (refereegranskat)abstract
- Chemical-looping combustion (CLC) is one of the most promising methods for CO2-capture. Regarding the use of solid fuels in CLC, it is assumed that the lifetime of the oxygen carrier material will be lowered preferring low cost and environmental sound materials. In this work apparent kinetics for the reduction of a natural rock ilmenite from Norway are derived from experimental data while utilizing CO, H2 and CH4 as fuel gases. CO, H2 and CH4 are the main combustible gases in solid fuel CLC. The experiments were carried out in a laboratory batch fluidized bed reactor. The reactor was heated to bed temperatures varying from 850 to 950 °C. Different fuel gas concentrations were achieved by diluting the fuel flow with nitrogen. For H2, pulsed reduction experiments have been accomplished to allow the calculation of conversion dependent rates. The experimental conversion rates were fitted to different model approaches in order to derive the apparent kinetic parameters. Thereby the oxygen carrier conversion was represented by the mass based conversion ω. The results are compared to published data. The reaction order with respect to the gas phase is close to the reported values. Only the reaction order obtained for CH 4 with the fitted power law deviated with about 40%, what could indicate a limitation of available surface for the heterogeneous decomposition of CH4. Although the overall agreement between fitted power laws and experimental data was appropriate, their extrapolation outside the experimental data range has to be done with care. © 2014 Elsevier Ltd.
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| 2. |
- Jani, Yahya, 1975-, et al.
(författare)
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Waste glass in the production of cement and concrete – A review
- 2014
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-3437. ; 2:3, s. 1767-1775
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Tidskriftsartikel (refereegranskat)abstract
- Cement and glass industries are facing a lot of challenges due to the high greenhouse gases emissions, the intensive use of energy and the intensive use of the earth’s natural resources. The current situation of discarding waste glass to landfills is also not offering an environmental friendly management for the waste glass, due to the nonbiodegradable form of the waste glass. However, the chemical composition and the pozzolanic properties of waste glass are encouraging for the use of this waste in the cement and concrete industries and to provide an environmental friendly solution for the glass and cement industries. This paper reviews the different uses of waste glass in cement and concrete and the effect of the glass properties on the performance and durability of the produce cement and concrete.
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| 3. |
- Lakshmanan, Ramnath, et al.
(författare)
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Microemulsion prepared magnetic nanoparticles for phosphate removal : Time efficient studies
- 2014
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-3437. ; 2:1, s. 185-189
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Tidskriftsartikel (refereegranskat)abstract
- The present study investigates the effective removal of phosphate in sewage wastewater using magnetic iron oxide nanoparticles (MION). The microemulsion-prepared magnetic iron oxide nanoparticles (ME-MION) of around 7-10 nm was synthesized using water-in-oil microemulsion method. The interaction of ME-MION and phosphate was studied using In situ FT-IR technique. Batch experiments were carried out with wastewater to determine the conc. and time efficiency using ME-MION for removal of phosphate. The vibration peak at 1004 cm-1 and the presence of hydroxyl group (OH-) at 3673 cm-1 confirms the binding of phosphate to ME-MION. ME-MION with 0.44 g L-1 exhibited more than 95% phosphate reduction in 5 min and close to 100% in 20 min. Conversely the experimental data obtained has been fitted with Langmuir isotherm model and also exhibited high correlation coefficients. The ME-MION was regenerated and can be reused for minimum 5 consecutive times. Efficient and fast reduction of phosphate was attained while the recovery of nanoparticles was achieved by an external magnetic field. To the author's knowledge, this is the first report that underscores around 100% phosphate removal from wastewater using ME-MION in 20 min. The approach utilized in this study offers a potential technique in the reduction of phosphate in wastewater whilst, reducing the time and reuse of nanoparticles.
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| 4. |
- Menya, Emmanuel, 1982-, et al.
(författare)
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Assessment of pollution levels resulting from biomass gasification
- 2014
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-3437. ; 2:3, s. 1228-1235
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Tidskriftsartikel (refereegranskat)abstract
- In biomass gasification process the producer gas generated can be cleaned by water scrubbing. Some of the organic compounds generated are entrained together with other flue gas dust particles in to the cooling stream. The treatment/disposal of this waste stream remains a challenge because some of the compounds are toxic to humans and the environment. The objective of this study was to assess pollution levels resulting from organic constituents of flue gas filtration in a downdraft gasifier. The study involved assessment of the concentration of polycyclic aromatic hydrocarbons (PAHs) in the liquid effluence. The impacts on human health and environment are also discussed and recommendations on measures to minimize the pollution levels are provided. A downdraft gasifier fed with maize cobs was used and condensates were collected by cooling of producer gas. Samples were preserved in a cooler at about 2 degrees C for 24 h before analysis using a capillary gas chromatographer connected to a mass spectrometer (GCMS). The results were that concentrations of: naphthalene was 204.3 mg/m, benzene 17.92 mg/m(3), toluene 182.94 mg/m(3), ethylbenzene 202.43 mg/m(3), 1,2-dimethyl benzene 359.28 mg/m(3) and 1,3+1,4-dimethyl benzene 1016.18 mg/m(3). It was observed that the concentrations of naphthalene and xylene were considerably higher than the recommended permissible exposure limits (PELs) on both human health and the environment. On the other hand, the concentrations of benzene, toluene, and ethylbenzene were below the PEL. Generally this study indicated that the liquid effluent meets regulatory standards, but it would be interesting to carryout tests with different biomass fuel types which this study recommends.
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