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Metal exchanged zeolites for catalytic decomposition of N2O
No full textRu + Ag/US-Y and Ru + Co/US-Y based catalysts have been studied for their catalytic activity towards
N2O decomposition, a reaction of current environmental importance. Ruthenium-cobalt based catalyst
shows higher catalytic activity than the ruthenium-silver-based catalyst. Almost 90% conversion ofN2O
is achieved over Ru + Co/US-Y at 583 Kwith amaximumof 0.134 mmol of N2O decomposed per gramof
the catalyst per unit time. These catalytic materials have been characterized for their structure,
composition, morphology etc. using XRD, SEM, EDX, ICP, BET techniques. The synergistic effect of
transition metals as well as chemical properties of US-Y are responsible for the excellent catalytic
activity for N2O decomposition reaction. The redox capacity of Co may also be responsible for the
relatively better activity of Ru + Co based catalyst as compared to that of Ru + Ag based catalyst. These
catalysts are thermally stable and can be used for the direct decomposition ofN2Oemissions even under
high concentration
Water Quality Problems in Ground Water Sources of Yavatmal District, Maharashtra, India - A Case Study
No full textTransgenic plants for phytoremediation of Arsenic and Chromium to enhance tolerance and hyperaccumulation
Get PDFPhytoremediation of metals and other environmental pollutants is gaining importance as a cost-effective method for pollution mitigation and envisages sustainable development. This paper envisages prospects of phytoremediation for mitigation of heavy metal pollutants from the environment, with particular reference to arsenic (As) and chromium (Cr). Genetically engineered tailor-made plants have much potential for selective uptake, accumulation and sequestration of heavy metals. Recent developments in this area and state-of-the-art technology foresee genetically engineered plants with an ability to prevent accumulation of As in aerial parts of experimental plant systems, which could be extrapolated to edible plants such as rice, wheat and others. Similarly, hypereaccumulation in plant biomass is another important approach for removal of these toxic metals from the land and water ecosystems and mitigation of As and Cr pollution. The mechanisms of As hyperaccumulation by the hyperaccumulator plants has opened up scope for genetic engineering other prospective plant species to enhance hyperaccumulation of toxic metals in their aerial biomass. This review enumerates the mechanisms of hyperaccumulation in the plant systems, the potential genes that could be engineered to develop tailor made genetically engineered plants aimed for phytoremediation of As and Cr and other metals in general
Chlorophyll-based photocatalysts and their evaluations for methyl orange photoreduction
No full textImmobilization of chlorophyll on different functionalized mesoporous materials has been attempted.
The replacement of butanediol with monoethanol amine has resulted in increase in chlorophyll loading
by a factor of two. The maximum immobilization of chlorophyll was on MCM-41 functionalized with
monoethanolamine MCM-41/MEA/Chl) as compared to other mesoporous materials. This material has
been characterized using XRD, UV–vis diffuse reflectance spectroscopy, scanning electron microscopy
(SEM-EDX) and fluorescence spectroscopy. The photocatalytic reduction ofmethyl orange (MO)was studied
using MCM-41/MEA/Chl as photocatalyst under the visible light. The photocatalytic reduction of MO
was 0.396 mg/g of MCM-41/MEA/Chl photocatalyst as compared to 0.508 mg/g of TiO2 for that of Degussa
P-25 photocatalyst. The effect of various operating parameters like catalyst loading, initial concentration
and intensity of light has also been studied. Photocatalytic property of chlorophyll-based photocatalytic
material indicates that chlorophyll acts as a reaction center, which absorbs visible light and generates
electron, which is transferred to different electron acceptors reducing MO into derivative of hydrazine
La3.5Ru4.0O13 Perovskite type Catalyst for Carbon Monoxide and Hydrocarbon Oxidation
No full textRuthenium based catalysts show excellent catalytic
activity for several oxidation reactions, however,
their thermal stability has been a challenge. We have been
successful in stabilizing ruthenium in perovskite structure,
which results in a remarkable improvement in its thermal
stability. La3.5Ru4.0O13 lanthanum ruthenate type perovskite
was prepared by using various methods, including coprecipitation
as well as a template method, which resulted
in improved physical properties. This perovskite phase was
found to be thermally very stable, possibly due to the 4?
oxidation state of ruthenium in a stable matrix. In this work,
we have studied the catalytic properties of La3.5Ru4.0O13
phase for CO and hydrocarbon oxidation reactions. The
lanthanum ruthenate shows active CO oxidation beyond
about 150 and 170 �C for propene oxidation. The thermal
and chemical stability of this material makes it suitable for
various catalytic applications, while relatively insignificant
poisoning by SO2 is an important observation to further
explore
Catalytic Hydrogenation of Aqueous Phase Nitrate Over Fe/C Catalysts
No full textCatalytic hydrogenation of nitrate in water has
been carried out over Fe/C catalysts at ambient temperature
using batch and continuous reactors. In batch reaction
nitrate reduction activity of 2.9 mmol gmetal
-1 min-1 with
nearly 100% selectivity towards nitrogen was obtained.
Column study shows nitrate reduction below 5 ppm for an
initial concentration of 100 ppm. Break through capacity, to
reach concentration of 45 mg L-1, is more than 530 bed
volumes. The catalysts were characterized using XRD,
SEM–EDAX and XPS. With high selectivity and activity
the catalytic system in present study could be a potential
option for nitrate removal from water
Stable partial nitrification in an up-flow fixed-bed bioreactor under an oxygen limiting environment
No full textGreywater reuse in residential schools in Madhya Pradesh, India—A case study of cost–benefit analysis
No full textGreywater treatment and reuse systems were constructed in residential schools (Schools) in Madhya Pradesh, India and treated greywater was used for toilet flushing and irrigating the food crops. Cost–benefit analysis was undertaken for greywater reuse by considering internal and external costs and benefits. The internal costs consist of construction of a greywater reuse systemaswell as the operation and maintenance costs. The construction cost (material and labour costs) equalled Indian Rupee (INR)
50,300 (1 USD= 42.5 INR) and operation and maintenance cost is INR 5725 per year. Internal benefits were estimated to be INR 30,000 per year due to the reduction in tankered water. Appropriate valuation methodologies were applied to monetize external benefits such as savings on water nfrastructure, reuse of pollutants such as nitrogen, phosphorus and potassium (equivalent to market cost of chemical fertilizer). Monetary values of external benefits and costs in terms of environmental and health benefits
were derived by using scientific references. The environmental and health benefitswere estimated as INR
44,000 and INR 793,380 respectively. In summary, the internal and external benefits of greywater reuse are substantially higher than the internal and external costs
Bacterial reduction in genotoxicity of Direct Red 28 dye.
No full textDirect Red 28 (DR28) is a benzidine-based azo dye widely used in several countries. It has also been a subject of intense research for its anti-prion activity. Like other benzidine-based azo dyes, it is also carcinogenic and toxic. However, there are very few studies addressing its detoxification. In the present study, a Bacillus velezensis strain was used for detoxification of DR28. Toxicity was checked by a battery of highly sensitive genotoxicity assays like comet assay, DNA ladder formation, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay and flow cytometric Annexin V binding assay. HL-60 cell line was used as the test system. All the assays showed an initial increase in toxicity upon biodegradation due to release of mutagenic products, like benzidine and 4-aminobiphenyl, from the dye. These intermediates caused significant DNA damage and induced apoptosis in HL-60 cells. Then the culture degraded these mutagenic intermediates, due to which the toxicity was reduced gradually, finally resulting in nearly complete detoxification
Emerging Control Technologies for Volatile Organic Compounds
No full textEnvironmental problems associated with volatile organic
compounds (VOCs) in the atmosphere have provided the driving
force for sustained fundamental and applied research in the area of environmental remediation. Conventional methods currently used to treat VOCs include incineration, condensation, adsorption, and absorption. Incineration and condensation are cost-effective only for moderate to high VOC concentrations. Adsorption and absorption do not destroy VOCs but simply transfer them to another medium. The humid gas stream can plug the condenser and can fill
up the adsorption site of the adsorbent. However, none of these methods are cost-effective for the treatment of gas streams with low to moderate concentration and having large numbers of compounds, as the recovery and reuse of the compounds is not economically feasible. A host of alternative remediation technologies, which offer a number of advantages over conventional technologies, are
emerging. These include treatment of VOCs with spark-generated carbon aerosol particles, negative air ions treatment, treatment using mesoporous chromium oxide and silica fiber matrix, electrical discharge treatment, electron beam bombardment, and ultraviolet (UV) photooxidation mediated by heterogeneous photocatalyst
particles. This review discusses these emerging technologies against the backdrop of conventional approaches for VOC treatment