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Compost from sugar mill pressmud and distillery spent wash for sustainable agriculture
No full textThis paper describes the process for rapid composting of sugar mill pressmud and distillery spentwash by using microbial culture. These waste materials are processed to organic manure, a value added produce, which can be used to replenish soil nutrients. Replenishment of soil nutrients is essential since plants utilize them to generate a large amount of crop produce, year after year. Physico-chemical characteristics and the nutritive value of compost generated out of pressmud and distillery effluent have been found to support good plant growth. The product has gained wide utility as an ameliorating agent and as a soil conditioner to replenish soil nutrients for sustainable agriculture. Besides, composting is a suitable method for stabilization of organic wastes which avoids discharge of industrial wastes to land and water ecosystems that may cause pollution. Activated composting through microbial culture and appropriate conditions converts the organic matter of pressmud and spentwash into value added compost. The cumbersome bio-nondegradable portion of these wastes such as lignins, melanoidins and humic acid get converted to humus which is an essential component of soil and further enriches the soil for sustainable crop productivity
Hydrogen evolution by water splitting using novel composite zeolite-based photocatalyst
No full textNovel zeolite-based material showing photocatalytic properties in the visible light have been synthesized by incorporating TiO2, heteropolyacid
(HPA) and transition metal, namely cobalt. This material shows high efficiency for water splitting under visible light irradiation. Hydrogen
generation to the tune of 2171 mmol/h/g of TiO2 has been achieved for the composite photocatalyst synthesized as compared to H2 evolution rate to
the tune of 131.6 mmol/h/g of TiO2 for Degussa P25. This suggests that the TiO2 which gets effectively dispersed and stabilized on the surface of
zeolite works synergistically with cobalt and heteropolyacid to make the material active in visible light for evolution of hydrogen from water. TiO2
is the photocatalyst, HPA functions as the dye sensitiser as well as redox system; zeolite functions as support matrix and as electron acceptor in
synergy with cobalt. The probable mechanism for improved hydrogen evolution rate using such composite photocatalyst has been discussed
Thermal imaging of catalyst surface during catalytic dehydrogenation of cyclohexane under spray-pulsed conditions
No full textused during dehydrogenation of cyclohexane on Pt catalyst supported on active carbon cloth and alumite supports. A spray-pulsed reactor
with injection of atomized cyclohexane and to create alternate wet and dry conditions on the catalyst surface was used in this study. Since
the production rate of hydrogen via endothermic dehydrogenation reaction is greatly dependent on the temperature of the catalyst surface, the
temperature profile of the catalyst is important to observe. The observed change in the temperature profile at wet and dry conditions with
varying pulse injection frequency and corresponding product gas analysis reveals that the spray-pulse mode is useful in improving the catalyst
activity. Further, the comparison between activated carbon support and a more conductive support such as alumite is reported using thermal
imaging for more suitable support in this endothermic reaction
Estimation of effect of gasoline quality improvement on reduction of air toxic emissions in Dhaka
Get PDFGasoline quality improvement alone can reduce total pollution load from vehicles to a considerable extent. A spreadsheet-based model has been developed in the present study to demonstrate this. An annual emission inventory for gasoline-driven vehicles was prepared with respect to volatile organic compounds, toxic air pollutants and nitrogen oxides using vehicle popula
tion data, growth rate of vehicles and usage characteris-tics in Dhaka. Results of the present and projected air toxic emission inventory using planned improvement in gasoline quality reveal that an emission reduction of about 20% may be achieved. A significant reduction of about 60% in pollutants like benzene justifies gasoline quality improvement in a developing country like Bangladesh.
Keywords: Exhaust volatile organic compounds, gaso-line quality, polycyclic organic matter, toxic air pollutant
Solar-based photoreduction of methyl orange using zeolite supported photocatalytic materials
No full textA new class of novel photocatalysts has been prepared by supporting TiO2 on the zeolite matrix by various routes of synthesis.
Different transition metals like cobalt, nickel, and ruthenium have been incorporated in these photocatalysts, alongwith molybdenum
based heteropolyacid (HPA) to improve the photocatalytic activity of these materials. Photoreduction of methyl orange under solar
radiation was compared with photoreduction in presence of artificial visible light illumination to evaluate their photocatalytic activity.
The quantity of methyl orange photoreduced by the cobalt containing photocatalyst was about 2.40 mg/g of TiO2 under the influence of
sunlight as compared to 4.111 mg/g of TiO2 under artificial visible light illumination. However, the efficiency of the photocatalyst is high
as compared to P25 TiO2 under solar light (0.508 mg/g of TiO2). The high photocatalytic activity of these materials is due to the
synergistic effect of incorporation of transition metals in combination with TiO2 and HPA supported by the zeolite matrix. These
materials are being evaluated for photocatalytic water splitting
Defluoridation of drinking water using chitin, chitosan and lanthanum-modified chitosan
No full textChitin, a naturally occurring abundant biopolymer, and its deacetylated product chitosan has been widely used for metal adsorption from water
and wastewaters, but the application of these materials as an adsorbent to remove fluoride from drinking water has seldom been explored. In
this work the applicability of chitin, chitosan and 20%-lanthanum incorporated chitosan (20% La-chitosan) as adsorbents for the removal of
excess fluoride from drinking water was studied. The effects of various physico-chemical parameters such as pH, adsorbent dose, initial fluoride
concentration and the presence of interfering ions on adsorption of fluoride were studied. It was observed that the uptake of fluoride was maximum
at original pH (pH 6.7). The equilibrium adsorption data were fitted reasonably well for Freundlich isotherm model. The presence of chloride,
sulfate, carbonate and bicarbonate ions in drinking water greatly affect the uptake of fluoride indicating that these anions compete with sorption
of fluoride on 20% La-chitosan. The rate of adsorption was rapid and maximum fluoride uptake was attained within 20 min. The mechanism of
adsorption of fluoride on lanthanum-modified chitosan is also explained. The comparison of uptake of fluoride in distilled water and field water
shows relatively higher uptake of fluoride in distilled water. This could be due to the competing effect of other anions present and higher pH of the
field water
Zirconia supported Ru–Co bimetallic catalysts for diesel soot oxidation
No full textVarious amounts of ruthenia–cobaltate bimetallic catalyst supported on zirconia have been prepared by co-impregnation
method and their catalytic activity towards soot/carbon oxidation has been evaluated using TG technique under the loose contact
condition. These catalysts show good activity for carbon/soot oxidation, which is observed to be a factor of ruthenia content. The
thermal stability experiments confirmed the stability of catalytic materials in air at least up to 900 �C. In this way, ruthenia can be
easily dispersed on zirconia possibly through the solid solution formation, while its thermal stability can be significantly improved
by introducing a transition metal namely cobalt. Formation of Ru–Co bimetallic clusters over zirconia is probably responsible for
its thermal stability, while dissociative adsorption of oxygen on catalyst surface appears to be responsible for their catalytic activity
UVand visibly active photocatalysts forwater splitting reaction
No full textUV and visibly active photocatalytic materials based on zeolites have been designed, wherein, a hybrid photocatalytic material comprising
charge transfer complex namely, heteropolyacid, a semiconductor and transition metal have been incorporated in the zeolite matrix to facilitate
its usage for photoreduction of water to hydrogen. The photocatalytic materials synthesized using zeolite, TiO2 and heteropolyacid (HPA)
are active in the UV range and the hydrogen yield works out to be 3000 �mol/h/g of TiO2 catalyst in UV range, which is quite low as
compared to that reported in literature. The photocatalytic materials developed by incorporation of HPA, TiO2 and Co+2 are visibly active
and are performing well as compared to reported materials in terms of their photoreduction properties and show potential for water splitting
reaction in visible light. The maximum hydrogen yield works out to be 2304.9 �mol//h/g of TiO2 in visible range which is substantially high
as compared to other reported values for supported TiO2 based photocatalytic materials
Kinetics of decolourisation and biotransformation of direct black 38 by C. hominis and P. stutzeri.
No full textIn the present study, a consortium of Cardiobacterium hominis and Pseudomonas stutzeri was isolated from an effluent treatment plant of a textile industry, based on its ability to decolourise azo dyes including direct black 38 (DB38), a benzidine-based azo dye. The role of each culture in the decolourisation process was elucidated, and C. hominis was found to decolourise the dye. Although P. stutzeri could not decolourise the dye, it was found to synergistically enhance dye decolourisation activity of C. hominis by scavenging oxygen in the medium and creating an anaerobic condition (oxidation/reduction potential -440 mV), which is known to be necessary for azo dye decolourisation. Together, the cultures could decolourise 90.5% of 100 mg l(-1) DB38 within 24 h. Kinetics of DB38 decolourisation was also examined, and P. stutzeri was found to increase V (max) and K (m) of decolourisation activity of C. hominis by 3.6- and 3-fold, respectively. The study also revealed a pathway of DB38 degradation with the release of benzidine from DB38 and subsequent degradation of benzidine to 4-aminobiphenyl by the cultures