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Emissions of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs) to air from waste incinerators and high thermal processes in India
No full textThis study investigated dioxins and dioxinlike polychlorinated biphenyls in gasses emitted from waste incinerators and thermal processes in central and western parts of India. The concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans PCDDs/DFs) ranged from 0.0070 to 26.8140 ng toxicity equivalent (TEQ)/Nm3, and those of dioxin-like polychlorinated biphenyls (PCBs) ranged from 0.0001×10−1 to 0.0295 ng TEQ/Nm3. The characteristics
of mean PCDD/F I-TEQ concentration and congener profiles were studied over all the samples of air. In particular, a pattern consisting of a low proportion of dioxin-like PCBs and high proportion of PCDDs/DFs was common for all the samples from incinerators and high-temperature processes
Probing the hydrogen equilibrium and kinetics in zeolite imidazolate frameworks via molecular dynamics and quasi-elastic neutron scattering experiments
No full textThe problem of simulating processes involving equilibria and dynamics of guest sorbates within
zeolitic imidazolate frameworks (ZIF) by means of molecular dynamics (MD) computer experiments
is of growing importance because of the promising role of ZIFs as molecular “traps” for clean energy
applications. A key issue for validating such an atomistic modeling attempt is the possibility of
comparing the MD results, with real experiments being able to capture analogous space and time
scales to the ones pertained to the computer experiments. In the present study, this prerequisite is
fulfilled through the quasi-elastic neutron scattering technique (QENS) for measuring self-diffusivity,
by elaborating the incoherent scattering signal of hydrogen nuclei. QENS and MD experiments were
performed in parallel to probe the hydrogen motion, for the first time in ZIF members. The predicted
and measured dynamics behaviors show considerable concentration variation of the hydrogen selfdiffusion
coefficient in the two topologically different ZIF pore networks of this study, the ZIF-3
and ZIF-8. Modeling options such as the flexibility of the entire matrix versus a rigid framework
version, the mobility of the imidazolate ligand, and the inclusion of quantum mechanical effects
in the potential functions were examined in detail for the sorption thermodynamics and kinetics
of hydrogen and also of deuterium, by employing MD combined with Widom averaging towards
studying phase equilibria. The latter methodology ensures a rigorous and efficient way for postprocessing
the dynamics trajectory, thereby avoiding stochastic moves via Monte Carlo simulation,
over the large number of configurational degrees of freedom a nonrigid framework encompasses.
© 2013 American Institute of Physics
Memory effect driven emissions of persistent organic Pollutants from industrial thermal processes, their implications and management: A review
No full textMemory effect is delayed emission of certain persistent organic pollutants (POPs). Many of the POP compounds viz. polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) get trapped in the particulate phase deposited in the flue transfer lines and air pollution control systems (equivalent to storage in the memory of a system) and released subsequently. Memory effect driven emission is a combination of real time emission and emission of stored compounds and so is not a true measure of actual real time emission. Memory effect is now realized to have existed for a long time but was not identified and understood until recently. Memory effect has several serious implications e.g. it wrongly depicts emission patterns of POPs; it makes
compliance to stipulated emission standards difficult; it could lead to wrong calculations of emission factors and emission inventory estimates of a plant and leads to misinterpretation of efficacy of processes and air pollution control systems. Further, new PCDD/Fs may be formed in the trapped particulate phase via de novo synthesis and the new compounds may be emitted, thereby increasing total PCDD/F emissions,apart from altering the homologue pattern of PCDD/Fs in emissions. Memory effect could be minimized by judicious operational and management (O&M) procedures like optimizing combustion, minimizing unnecessary halts in operations, periodical cleaning of flue transfer lines, application of inhibitors etc.
Intellectual property rights in plant biotechnology: relevance, present status, and future prospects
No full textThe IPR has relevance to each and every field of development, such as health, agriculture, education, trade, biodiversity management, biotechnology, information technology, the entertainment and media industries, and so on. Further, with the advent of the IPR, the gap between developed, developing, and least-developed countries is widening and there is a need for its stringent regulation worldwide. There has been substantial advancement in scientific research owing to collaborations but the issue of IPR needs to be addressed
Intellectual property rights in plant biotechnology: relevance, present status, and future prospects
No full textEnvironmental exposure to heavy metals such as arsenic and chromium has become a serious problem worldwide. The recent advances in the knowledge of metal hyperaccumulation by some plant species have recognized phytoextraction as a prospective proposition using hyperaccumulator plants. This paper enumerates the progress in phytoextraction of metals using fern species with emphasis on the arsenic hyperaccumulator Pteris vittata. The scopes of R&D for value addition in ferns for efficient phytoremediation application have also been discussed
Catalytic preferential oxidation of carbon monoxide over platinum supported on lanthanum ferriteeceria catalysts for cleaning of hydrogen
No full textSince hydrogen is produced by reforming of hydrocarbon it contains carbon monoxide (CO). In order to make hydrogen suitable for proton exchange membrane fuel cell application there is need to reduce concentration of CO less than 100 ppm. WatereGas-Shift reactions subsequent to reforming lower CO concentration in H2 to about 1e1.5% by volume. Preferential oxidation of CO (PROXeCO) using a catalyst is therefore important for further cleaning up of CO from H2. The catalyst in this study is platinum supported over lanthanum ferriteeceria (Pt/LaFeO3eCeO2) exhibits excellent activity of 99.8% and selectivity of 95.7% at a relatively lower temperature of 100 _C with an equivalence ratio of 3 for PROX eCO. The concentration of CO is reduced from 1% v/v in feed to ca. 30 ppm in product gas with rela-tively lower loss of hydrogen is the most significant achievement in this study. The catalyst is selective towards CO oxidation as the hydrogen loss is relatively low (ca. 3.8%) and there is no methane formation. The improvement in catalytic activity and selectivity is attributed to the strong metal support interaction and open morphology of catalyst. The results obtained in this study reveal the excellent catalytic activity by using LaFeO3eCeO2 as support for Pt catalyst
Prioritizing hazardous pollutants in two Nigerian water supply schemes: a risk-based approach
Get PDFObjective
To rank pollutants in two Nigerian water supply schemes according to their effect on human health using a risk-based approach.
Methods
Hazardous pollutants in drinking-water in the study area were identified from a literature search and selected pollutants were monitored from April 2010 to December 2011 in catchments, treatment works and consumer taps. The disease burden due to each pollutant was estimated in disability-adjusted life years (DALYs) using data on the pollutant's concentration, exposure to the pollutant, the severity of its health effects and the consumer population.
Findings
The pollutants identified were microbial organisms, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead and zinc. All were detected in the catchments but only cadmium, cobalt, chromium, manganese and lead exceeded World Health Organization (WHO) guideline values after water treatment. Post-treatment contamination was observed. The estimated disease burden was greatest for chromium in both schemes, followed in decreasing order by cadmium, lead, manganese and cobalt. The total disease burden of all pollutants in the two schemes was 46 000 and 9500 DALYs per year or 0.14 and 0.088 DALYs per person per year, respectively, much higher than the WHO reference level of 1 × 10−6 DALYs per person per year. For each metal, the disease burden exceeded the reference level and was comparable with that due to microbial contamination reported elsewhere in Africa.
Conclusion
The estimated disease burden of metal contamination of two Nigerian water supply systems was high. It could best be reduced by protection of water catchment and pretreatment by electrocoagulation
A TRITERPENOID SAPONIN FROM THE SEEDS OF Ricinus communis AND ITS ANTIMICROBIAL ACTIVITY
No full textA new oleanene triterpenoid was isolated from the butanolic seed extract of Ricinus communis. Its structure
was elucidated as 3-O-[�-D-glucuronopyranosyl-(1�3)-�-L-rhamnopyranosyl-(1�2)�-D-glucopyranosyl]-
4�,20�-di(hydroxymethyl)olean-12-en-28-oic acid on the basis of spectral evidence i.e., FTIR, 1H and
13C NMR, and FAB-MS data. The isolated triterpenoid was found to have antimicrobial potential, viz.
antibacterial and antifungal activity, where the growth of microbes was found to be an inverse function of
the concentration of saponin. The MIC value for E. coli, Klebsiella pneumoniae and Staphylococcus aureus
were found to be 260, 235, and 350 �g/mL
Metal Hyperaccumulating Ferns: Progress and Future Prospects
No full textEnvironmental exposure to heavy metals such as arsenic and chromium has become a serious problem worldwide. The recent advances in the knowledge of metal hyperaccumulation by some plant species have recognized phytoextraction as a prospective proposition using hyperaccumulator plants. This paper enumerates the progress in phytoextraction of metals using fern species with emphasis on the arsenic hyperaccumulator Pteris vittata. The scopes of R&D for value addition in ferns for efficient phytoremediation application have also been discussed
Non-noble NieCu/ACC bimetallic catalyst for dehydrogenation of liquid organic hydrides for hydrogen storage
No full textThe effect of Cu on dehydrogenation activity of Ni has been observed when dehydrogenation
of methyl cyclohexane (MCH) was carried out by using bimetallic NieCu supported
on activated carbon cloth (ACC) catalysts with various Ni to Cu ratios and constant total
metal content of about 10 wt%. The dehydrogenation of MCH was studied for delivery of
clean hydrogen to hydrogen fueling station. Catalysts have been synthesized by adsorption
method and characterized by atomic absorption spectroscopy (AAS), X-ray powder
diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Among all combinations of
this study 8 wt% Ni þ 2 wt% Cu/ACC was found to show strong synergetic effect. This
catalyst exhibited relatively high H2 evolution rate 39.4 mmol/gmet/min during the dehydrogenation
of MCH. At the same time methane evolution rate was relatively low which
indicated insignificant side reaction of hydrogenolysis. The study reveals that presence of
specific amount of Cu enhances the dehydrogenation activity of Ni and suppresses the
hydrogenolysis activity for the same. The NieCu/ACC catalyst may be a potential nonnoble
metal catalyst for dehydrogenation reaction