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Low Cost, Ceria Promoted Perovskite Type Catalysts for Diesel Soot Oxidation
No full textPerovskite type catalysts with SrCoO3 and
Sr0.8Ce0.2CoO3 compositions have been prepared by
co-precipitation and other methods and, their catalytic
activity towards diesel particulate matter (PM)/carbon
oxidation has been evaluated under the loose contact condition.
These catalysts show excellent catalytic activity for
PM/carbon oxidation, despite their low surface area and
under the loose contact condition. The synergistic effects of
Ce incorporation in perovskite and presence of a small
amount of potassium appears to be responsible for the high
soot oxidation activity of these perovskite type materials.
The Ce incorporation seems to be contributing by
enhancing the redox property of the catalyst, while it
appears unlikely that potassium is contributing by
improving the catalyst–soot contact through its volatization.
The catalysts show excellent thermal stability and
stable activity under repeated cycles of use
Lateral gene transfer in phylogeny of azoreductase enzyme.
No full textThis paper attempts to reconstruct the phylogeny of azoreductase enzyme from different organisms and compare it with the small subunit rRNA-based phylogeny of the organisms. The two phylogenies were found to be incongruent, indicating several events of lateral transfer of azoreductase gene between phylogenetically diverse organisms. However, the phylogenetic analysis methods have several limitations and a single method may not give the true pattern. Hence, it is necessary to corroborate the results with other complementary analysis tools. We used several tools to test our hypothesis of lateral transfer and found that it was supported not only by the analysis of the whole sequences, but also by the conserved motifs detected in these sequences. There were ample evidences for lateral transfer of azoreductase gene among enteric bacteria. There were also indications that azoreductase probably evolved in prokaryotes and then it was laterally transferred to eukaryotes in multiple events, resulting in some sequence variation among eukaryotic azoreductases. Finally, profile HMMs and conserved motifs extracted from these azoreductase sequences were found to provide sensitive tools for identifying potential azoreductases from the database. The analysis techniques used in this study can be extended to other gene trees to verify their evolutionary histories
Assessment of Groundwater Quality with Respect to Fluoride
No full textAbstract The study was conducted in the summer season
(April–May 2007). The fluoride concentration along with
physico-chemical parameters in ground water samples was
determined in various villages of Kadi tehsil at Mehsana
district of Gujarat state (India), since in most of the villages
it is the only source of drinking water. The fluoride concentrations
in these villages varied from 0.94 to 2.81 mg/L
(1.37 ± 0.56) with highest fluoride level at Visalpur
(2.08 mg/L) and lowest at Adaraj (0.91 mg/L). There was
found a positive correlation of pH with fluoride and a
negative relationship of fluoride with bicarbonate which is
generally observed in deep ground water
Production of cellulase and xylanase by Trichoderma reesei (QM 9414 mutant) Aspergillus niger and mixed culture by solid state fermentation (SSF) of water hyacinth (Eicchornia crassipes)
No full textVisible light active zeolite-based photocatalysts for hydrogen evolution from water
No full textHydrogen, considered as the fuel for future can be produced from non-conventional,
renewable and plentiful source like water. Novel zeolite-based materials that show photocatalytic
properties in the visible light have been synthesized by incorporating titanium
dioxide (TiO2), heteropolyacid (HPA) and transition metals like cobalt (Co). These materials
show high efficiency for water splitting under visible light irradiation. Hydrogen (H2)
generation to the tune of 2730 mmol/h/g TiO2 has been obtained for the composite
photocatalyst synthesized. Platinum (Pt) doping has also been attempted in this composite
photocatalyst, however, no substantial enhancement in hydrogen generation was
observed. The high efficiency of the composite photocatalyst suggests that the TiO2 which
gets effectively dispersed and stabilized on the surface of zeolite works synergistically with
transition metal like cobalt and heteropolyacid to make the material active in visible light
for photoreduction of water to hydrogen. The aluminosilicate framework of zeolite also
contributes towards delayed charge separation. This composite photocatalyst shows
improvement in hydrogen evolution rate over other TiO2 based visibly active photocatalyst
reported
Composition and size distribution of particules emissions from a coal-fired power plant in India
No full textParticulate matter in fly ash from ESP inlet and outlet of a coal fired power plant in India was measured for five units of 120MW and 210 MWof the power plant. Samples of the pulverised coal and bottom and fly ashes were also collected. The size distribution and chemical composition of particulate matter were determined using a laser particle analyser, an ion chromatograph (IC) and an inductively
coupled plasma-atomic emission spectrometer (ICP-AES). The observed particle mass concentration at the ESP inlet was 5443–21483 mg Nm�3 whereas the outlet concentration was found as 12–315 mg Nm�3 thereby giving total removal efficiency of 95.7–99.8%. A fine particle mode appeared at the particle size of 0.4–0.9 lm and coarse particle mode appeared at the particle size greater than 1 lm. Magnesium and iron remained in bottom ash and showed high concentrations 99 and 2154 lg g�1 (ppmw) respectively, while other elements such as lead, chromium and zinc were observed in higher concentration in ESP inlet flue gas. Relative enrichment of trace elements (except Fe) in fly ash was observed higher than that in bottom ash
Azoreductase and dye detoxification activities of Bacillus velezensis strain AB.
No full textAzo dyes are known to be a very important and widely used class of toxic and carcinogenic compounds. Although lot of research has been carried out for their removal from industrial effluents, very little attention is given to changes in their toxicity and mutagenicity during the treatment processes. Present investigation describes isolation of a Bacillus velezensis culture capable of degrading azo dye Direct Red 28 (DR28). Azoreductase enzyme was isolated from it, and its molecular weight was found to be 60 kDa. The enzyme required NADH as cofactor and was oxygen-insensitive. Toxicity and mutagenicity of the dye during biodegradation was monitored by using a battery of carefully selected in vitro tests. The culture was found to degrade DR28 to benzidine and 4-aminobiphenyl, both of which are potent mutagens. However, on longer incubation, both the compounds were degraded further, resulting in reduction in toxicity and mutagenicity of the dye. Thus, the culture seems to be a suitable candidate for further study for both decolourization and detoxification of azo dyes, resulting in their safe disposal
Chemical hydrides: A solution to high capacity hydrogen storage and supply
No full textCycloalkanes are good candidate media for hydrogen storage (6.5 wt% and 60.62 kg H2/m3). A novel approach for the supply of hydrogen,
through liquid organic hydrides (LOH) using catalytic reaction pair of dehydrogenation of cycloalkanes and hydrogenation of corresponding
aromatics is a useful process for supply of hydrogen. Hydrogenation of aromatics is relatively well-established process. However, the efforts
are needed to develop efficient catalyst for dehydrogenation of cycloalkanes. In this paper we review the dehydrogenation of cycloalkanes as
useful reaction for storage of hydrogen in chemical hydrides.
2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved
Nitric Oxide Reduction Using Hydrogen Over Perovskite Catalysts with Promotional Effect of Platinum on Catalytic Activity
No full textThe catalytic activities of strontium substituted
La0.7Sr0.3MnO3 type perovskite catalysts for NO reduction
using H2 as reducing agent has been studied, which is further
improved by incorporation of Pt outside (0.1 wt.%Pt/
La0.7Sr0.3MnO3) and inside (La0.7Sr0.3Mn0.97Pt0.03O3) the
perovskite lattice structure. Pt shows excellent enhancement
in catalytic selectivity towards N2 when supported on
the perovskite. The catalysts were characterized using
thermo-gravimetric analysis (TGA), X-ray diffraction
(XRD), scanning electron microscopy (SEM) and specific
surface area. Catalysts evaluations were carried out using
thermo-gravimetric analysis coupled with mass spectra
(TG-MS)
Biological decolourization of C.I. Direct Black 38 by E. gallinarum.
No full textIn the present study, an Enterococcus gallinarum strain was isolated from effluent treatment plant of a textile industry based on its ability to decolourize C.I. Direct Black 38 (DB38), a benzidine-based azo dye. Effects of dye concentration and medium composition on dye decolourization were studied. The strain was found to decolourize DB38 even under aerobic conditions. Kinetics of DB38 decolourization was also examined, and V(max) and K(s) of decolourization were found to be higher in Luria broth (12.8 mg l(-1)h(-1) and 490.6 mg l(-1)) than in minimal medium (4.09 mg l(-1)h(-1) and 161.84 mg l(-1)). However, decolourization rate/biomass was found to be higher in minimal medium than in Luria broth, indicating greater decolourization efficiency of biomass in the former. The study also revealed biodegradation of DB38 to benzidine and its further deamination to 4-aminobiphenyl (4-ABP) by the culture. Ammonia released during this process was used as nitrogen source for growth of the culture