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Adsorption of fluoride from aqueous solution by alumina of alkoxide nature: Batch and continuous operation
No full textIn this investigation, we report the adsorption potential of alkoxide origin alumina for defluoridation of
drinking water using batch and continuous mode of operations. The effects of different operating parameters
such as adsorbent dose, initial fluoride concentration, pH of the solution and interfering ions (usually present
in groundwater) were studied with a view to understand the adsorption behavior of the material under
various conditions. A thermodynamic study shows that the adsorption of fluoride by alkoxide origin alumina
is an exothermic and spontaneous process. The kinetic results showed that the fluoride sorption follows
pseudo-second-order kinetics. The applicability of adsorbent in the field is also tested through column
breakthrough studies. It has been observed that with an increase in the flow rate and initial fluoride
concentration, the breakthrough curve becomes sharper and the breakthrough time and adsorbed fluoride
ion concentration decrease. The breakthrough curve also becomes steeper as the bed height increases. The
alkoxide origin alumina based adsorbent media can be used directly for field applications since it is also
commercially available in granular form
Impact of phosphorus on biochemical changes in hordeum vulgare L in mixed croping with chickpea
No full textPure phase LaFeO3 perovskite with improved surface area synthesized using different routes and its characterization
No full textThree different wet chemistry routes, namely co-precipitation, combustion and sol–gel methods were used to synthesize LaFeO3 perovskite with improved surface area. The synthesized perovskite was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), Brunauer–Emmett–Teller (BET) nitrogen adsorption, ultraviolet diffused reflectance spectroscopy (UVDRS) and Fourier transform infrared (FTIR) spectroscopy techniques. Improved surface area was observed for all three methods as compared to the previously reported values. The perovskite synthesized using sol–gel method yields comparatively pure, crystalline phase of LaFeO3 and relatively higher surface area of 16.5 m2 g−1 and porosity. The material synthesized using co-precipitation method yielded other phases in addition to the targeted phase. The morphology of perovskite synthesized using co-precipitation method was uniform agglomerates. Combustion method yields flakes type morphology and that of sol–gel method was open pore type morphology. The selection of method for perovskite synthesis largely depends on the targeted application and the desired properties of perovskites. The results reported in this study are useful for establishing a simple scalable method for preparation of high surface area LaFeO3 as compared to solid-oxide method. Further, the typical heating cycle followed for calcinations resulted in relatively high surface area in the case of all three methods
Antigenotoxic potential of Gymnema montanum leaves on DNA damage in human peripheral blood lymphocytes and HL-60 cell line
No full textIn this study we have evaluated the genoprotective
effect of the ethanol extract of Gymnema montanum
(GLEt) leaves in human peripheral blood lymphocytes
and HL-60 cell line in vitro using the
comet assay. DNA damage was induced by treating
the cells with H2O2 and methyl methane
sulphonate (MMS). GLEt treatment effectively protected
the lymphocytes and HL-60 cell line from
H2O2-induced oxidative DNA damage in a dosedependent
manner whereas it was not effective
against alkylative DNA damage caused by MMS.
The global percent repair efficiency also showed
that both pre- and post- GLEt treatment provided
effective protection against H2O2 induced DNA
damage but not as effective against MMS. At
200 lg ml21 level, its repair capacity against
H2O2 induced DNA damage was comparable to
that of vitamin-C (100 lM). Furthermore, exposure
to GLEt reduced the formation of apoptotic cells
caused by H2O2, which was demonstrated by the
decreased sub-G1-DNA content in cell cycle analysis
and apoptotic frequencies of lymphocytes in
an annexin-V binding assay. In addition, GLEt
was found to have effective peroxide scavenging
ability in dose-dependent manner. The protective
efficiency of the extract was found to be directly
proportional to its total phenolic content. The present
study indicates that G. montanum leaves are a
significant source of phytochemicals with antigenotoxic
and antioxidant activity, and thus has
potential therapeutic use. Environ. Mol. Mutage
Assessment of heavy metal content in suspended particulate matter of coastal industrial town, Mithapur, Gujarat, India
No full textHeavy metal concentrations in suspended particulate matter (SPM) were investigated for their
distribution and source in the atmosphere of coastal industrial town, Mithapur, Gujarat, India.
SPM, at 10 locations covering three seasons, were trapped on glass fibre filters using high
volume samplers and quantification of metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) was done
using Atomic Absorption Spectrometry employing HNO3 based wet digestion. Results show
relatively low concentrations of SPM (211.3 to 375.2 μg/m3) compared to National Ambient Air
Quality Standard (NAAQS), specified By Central Pollution Control Board (CPCB, India),
however, they were 2–3 times higher as compared to reference site. Among the heavy
metals Cr, Mn and Pb levels were low, while Ni and Cd found to be exceeding the USEPA
standards. The metal levels were also compared with those reported for other rural, coastal,
industrial and urban parts around the world. Enrichment Factor analysis indicated that Cd, Zn,
Cu, Pb and Ni were highly enriched relative to their crustal ratios (to Fe) and correspond to
substantial contribution of anthropogenic source of these metals. The source identification was
carried out by principal component analysis by applying a Varimax Rotated Component Matrix
Influence of zeolitic structure on photoreduction property and hydrogen evolution reaction
No full textA new photocatalytic material developed by supporting TiO2 in combination with transition
metal ion like cobalt and heteropolyacid (HPA) on the surface is facilitating enhanced
photoreduction of water and methyl orange. Zeolites being a solid acid play an important
role in the electron transfer reaction, facilitated by the Lewis acid sites in the form of
aluminium ions. In the present work, four different zeolite matrices namely, NaY zeolite,
ultrastable zeolite Y, beta zeolite and titanium silicate-1 have been used for the synthesis
of new photocatalytic materials. These materials have been evaluated for water splitting by
an initial screening procedure using methyl orange photoreduction. The photocatalyst
containing Na Y has emerged as a potential photocatalyst with hydrogen evolution rate of
2730 mmol/h/g of TiO2. Hydrogen evolution was not observed for the composite photocatalysts
synthesized using the other zeolite matrices. It has been observed that physicochemical
properties like Si/Al ratio, acidity and basicity of the zeolite support have
a tremendous influence on the photoreduction property of these zeolite matrices
Seasonal Varation of Trihalomethane Formation Potential in Treated Water Supplies in Delhi City, India
No full textHydrogen evolution by a low cost photocatalyst: Bauxite residue
No full textBauxite residue or red mud which is an aluminium industry waste has been used as a novel
low cost photocatalyst active in visible light for the generation of hydrogen from water. The
driving force behind the use of bauxite residue as a photocatalyst is not only the fact that it
is widely available but also bauxite residue is a fine grained mixture of oxides and
hydroxides (Fe2O3, TiO2, SiO2, and Al2O3, Al(OH)3). The photocatalyst was characterized
with respect to BET-SA, UV-DRS, XRD, SEM and EDX. Hydrogen yield of 4600 mmol/h/g of
TiO2 was achieved as compared to hydrogen evolution rate of 164 mmol/h/g of TiO2 for
commercially available titania Degussa P-25. However, the hydrogen evolution was
20.85 mmol/h/g of photocatalyst. The results suggest that bauxite residue appears to be
a novel low cost photocatalyst. The various operating conditions of photocatalytic
hydrogen generation were studied which include amount of catalyst, illumination intensity,
illumination time, effect of various sacrificial donors etc
Chitosan based mesoporous Ti–Al binary metal oxide supported beads for defluoridation of water
No full textIn the present study, the performance of Ti–Al binary metal oxide supported beads using chitosan
template was studied for fluoride removal from drinking water. The adsorbent was synthesized by
precipitation method and characterized using FTIR, SEM, XRD and BET. The higher surface area of the
synthesized adsorbent 323.83m2/g results in a much higher fluoride removal capacity Qmax = 2.22mgg−1
as compared to bare chitosan. Pore size of beads is 42.97 Å, suggesting mesoporous nature of adsorbent.
Material works very effectively at all pH except at pH greater than 9. The presence of carbonate and bicarbonate
ions showed significant decline in the fluoride removal capacity of adsorbent. The experimental
data fitted well to Langmuir adsorption model. The kinetic studies indicate that the system follows the
pseudo-second-order and intra-particle diffusion model. Thermodynamic study reveals that the fluoride
adsorption by Ti–Al binary metal oxide supported beads is an exothermic and spontaneous process.
Alum appears to be the promising regeneration media showing 80% regeneration. The applicability of
the adsorbent for fluoride removal was tested in field water collected from the Dhar district in Madhaya
Pradesh, India
Efficient hydrogen supply through catalytic dehydrogenation of methylcyclohexane over Pt/metal oxide catalystsEfficient hydrogen supply through catalytic dehydrogenation of methylcyclohexane over Pt/metal oxide catalysts
No full textThis paper describes the results of experiments on dehydrogenation of methylcyclohexane over Pt supported on metal oxides (Pt/MO) and Pt supported on perovskite (Pt/Per) catalysts. The reaction is being considered as a means for delivery of hydrogen to fueling stations in the form of more easily transportable methylcyclohexane. Among Pt/MO catalysts, the best activity as determined by the hydrogen evolution rate was observed over Pt/La2O3 catalyst at 21.1 mmol/gmet/min. Perovskite-supported catalysts exhibited relatively higher activity and selectivity, with Pt/La0.7Y0.3NiO3 giving the best performance. This Pt/Per catalyst had an activity of ca 45 mmol/gmet/min with nearly 100% selectivity towards dehydrogenation. The catalysts were characterized using XRD, CO-chemisorption and SEM-EDXA techniques. The present study reports catalysts that minimize the use of Pt and explores tailoring the properties of the perovskite structure