Liquid-liquid extraction and flat sheet supported liquid membrane studies on Am(III) and Eu(III) separation using 2,6-bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine as the extractant

Solvent extraction and supported liquid membrane transport studies for the preferential removal of Am(3+) from feeds containing a mixture of Am(3+) and Eu(3+) was carried out using 2,6-bis(5,6-dipropyl-1,2,4-triazin-3-yl)pyridine (n-Pr-BTP) as the extractant. Diluent plays an important role in these studies. It was observed that the distribution coefficients deteriorate significantly for both Am(3+) and Eu(3+) though the separation factors were affected only marginally. The transport studies were carried out at pH 2.0 in the presence of NaNO(3) to result in the preferential Am(3+) transport with high separation factors. Effect of different experimental parameters, viz. feed composition, stripping agents, diluents of the organic liquid membrane and membrane pore size was studied on the transport and separation behaviour of Am(3+) and Eu(3+). The supported liquid membrane studies indicated about 85% Am(3+) and 6% Eu(3+) transport in 6h using 0.03 M n-Pr-BTP in n-dodecane/1-octanol (7:3) diluent mixture for a feed containing 1M NaNO(3) at pH 2 and a receiver phase containing pH 2 solution as the strippant. Consequently, a permeability coefficient of (1.75 ± 0.21) × 10(-4)cms(-1) was determined for the Am(3+) transport. Stability of the n-Pr-BTP and its SLM was also studied by carrying out the distribution and transport experiment after different time intervals.

Determinants for the retreatment groups of pulmonary tuberculosis patients treated in a DOTS programme in Sikkim, India

OBJECTIVE

To assess knowledge, attitude and different health-seeking behaviours among 250 cured and 250 category-II tuberculosis patients.

METHODS

A case-control study was conducted in different health settings in Sikkim, a part of the Indian continent. A questionnaire was filled for the purpose.

RESULTS

Results showed significant differences in overcrowding, smoking and alcohol intake. There was a general unawareness with the disease and its treatment between the two groups. 45% of the respondents reported that tuberculosis is caused by germs. 81.4% stated that tuberculosis presents only as cough. 94.8% of the case group and 90.8% of the control group stated that it is a transmissible disease. Sharing food with tuberculosis patients (64% of case group, 55% of the control group; p < 0.05), inadequate diet (16.4% of case group, 9.6% of the control group; p < 0.03) were mentioned as modes of transmission. Sixty six per cent of the case group and 56.8% of the control group mentioned the use of DOTS for prevention and control (p < 0.05). Sixty three per cent of the control group regarded tuberculosis as a life threatening condition (p < 0.00) [(adjusted OR = 2.04, (95% CI: 1.43, 2.93)]. Tuberculosis was considered as a completely curable disease by 96.4% of the case group (p < 0.05). 40.6% of the respondents agreed to be in contact with a tuberculosis infected person. 64% of the retreatment group discontinued their treatment due to frequent travelling for work.

CONCLUSION

The study revealed lack of knowledge, positive attitude and inappropriate health seeking behaviours among of the tuberculosis patients, irrespective of their categorization.

Studies on the selective Am3+ transport, irradiation stability and surface morphology of polymer inclusion membranes containing Cyanex-301 as carrier extractant

Transport behaviour of Am(3+) across cellulose triacetate (CTA) based polymer inclusion membranes (PIM) containing Cyanex-301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid) as the carrier extractant and tri-n-butyl phosphate (TBP) or 2-nitrophenyloctylether (NPOE) as the plasticizer was investigated from different feed and strip conditions. The TBP plasticized membrane resulted back transport of Am when alpha-hydroxy iso-butyric acid was used as the complexing agent in the strip phase while no such effect was seen when ethylene diamine tetraacetic acid (EDTA) was used as the complexant. Effect of varying Cyanex-301 concentration and bipyridyl (bipy) concentration on Am transport was also investigated. Long term reusability of the membrane was studied by measuring the permeability coefficient (P) after exposing the PIMs to a maximum gamma ray dose of ∼ 200 kGy. The surface morphology of the membranes was analyzed by atomic force microscopy and the roughness parameter was correlated to transport efficiency.

Extraction of caesium(I) from HNO3 medium using room temperature ionic liquid containing calix[4]crown ligands as the selective extractants

Studies on the extraction of Cs(I) from nitric acid medium were carried out using three commercial calix-crown ligands, viz. calix[4]arene-bis-crown-6, calix[4]arene-bis-1,2-benzocrown-6 and calix[4]arene-bis-2,3-naphthocrown-6 dissolved in different room temperature ionic liquids (RTILs), viz. 1-butyl-3-methyl-imidazolium hexafluorophosphate (C4mim·PF6), 1-hexyl-3-methyl-imidazolium hexafluorophosphate (C6mim·PF6) and 1-octyl-3-methyl-imidazolium hexafluorophosphate (C8mim·PF6). The distribution ratio of Cs(I) decreased with increased alkyl chain length of RTILs. The effect of nitric acid concentration on distribution behaviour of Cs(I) by calix[4]arene-bis-1,2-benzocrown-6 was investigated. The extraction of Cs(I) from HNO3 was found to be exothermic and extraction was found to be enthalpy driven. Selective extraction of Cs(I) could be achieved from a mixt ure of various fission product elements like Tc, Mo, Zr, Ce, Ru, La, Ba, and Sr.

Assessment of groundwater quality in Puri City, India: an impact of anthropogenic activities

Puri City is situated on the east coast of India and receives water supply only from the groundwater sources demarcated as water fields. The objective of this paper is to assess and evaluate the groundwater quality due to impact of anthropogenic activities in the city. Groundwater samples were collected from the water fields, hand pumps, open wells, and open water bodies during post-monsoon 2006 and summer 2007. Groundwater quality was evaluated with drinking water standards as prescribed by Bureau of Indian Standards and Environmental Protection Agency to assess the suitability. The study indicated seasonal variation of water-quality parameters within the water fields and city area. Groundwater in the water fields was found to be suitable for drinking after disinfection. While in city area, groundwater quality was impacted by onsite sanitary conditions. The study revealed that groundwater quality was deteriorated due to the discharge of effluent from septic tanks, soak pits, pit latrines, discharges of domestic wastewater in leaky drains, and leachate from solid waste dumpsite. Based on observed groundwater quality, various mitigation measures were suggested to protect the water fields and further groundwater contamination in the city.

Facilitated transport of uranium(VI) across supported liquid membranes containing T2EHDGA as the carrier extractant

Facilitated transport of uranyl ion from nitric acid feed solutions was investigated across PTFE supported liquid membranes using N,N,N',N'-tetra-2-ethylhexyl-3-pentane-diamide (T2EHDGA) in n-dodecane as the carrier extractant containing 30% iso-decanol as the phase modifier. Solvent extraction studies indicated extraction of species of the type, UO(2)(NO(3))(2)·T2EHDGA. The distribution coefficients increased in the presence of NaNO(3) as compared to equivalent concentration of HNO(3) which was exactly the opposite of what was reported for Am(III)-TODGA extraction system. Supported liquid membrane studies indicated about 11h were required for quantitative transport of U(VI) from a feed of 3M HNO(3) using 0.2M T2EHDGA in n-dodecane containing 30% iso-decanol as the carrier extractant. Effect of various parameters such as feed acidity, T2EHDGA concentration, and nature of the strippant on the transport rate was investigated. The transport was found to be diffusion controlled in the membrane phase and the permeability coefficient was calculated to be (3.20 ± 0.13)× 10(-4)cm/s for the feed composition of 3M HNO(3), receiver phase composition of 0.01 M HNO(3) and membrane carrier phase of 0.2M T2EHDGA in n-dodecane containing 30% iso-decanol. The present results may be useful for the separation of U from lean solutions or radioactive wastes considered hazardous due to the presence of alpha-particle emitting radionuclides.

Determination of processes affecting groundwater quality in the coastal aquifer beneath Puri city, India: a multivariate statistical approach

Variability of groundwater quality parameters is linked to various processes such as weathering, organic matter degradation, aerobic respiration, iron reduction, mineral dissolution and precipitation, cation exchange and mixing of salt water with fresh water. Multivariate statistical analyses such as principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to the standardized data set of eleven groundwater quality parameters (i.e. pH, Ca2+, Mg2+, Na+, K+, Fe3+, alkalinity, NO3-, Cl-, SO4(2-), TDS) collected during the post-monsoon and the summer seasons in order to elicit hydrologic and biogeochemical processes affecting water quality in the unconfined aquifer beneath Puri city in eastern India. The application of PCA resulted in four factors explaining 73% variance in post-monsoon and 81% variance in summer. The HCA using Ward's method and squared Euclidean distance measure classified the parameters into four clusters based on their similarities. PCA and HCA allowed interpretation of processes. During both post-monsoon and summer seasons, anthropogenic pollution and organic matter degradation/Fe(III) reduction were found dominant due to contribution from on-site sanitation in septic tanks and soak pits in the city. Cation exchange and mineral precipitation were possible causes for increase in Na+ and decrease in Ca2+ concentration in summer. Fresh water recharge during monsoon and Sea water intrusion in summer are attributed as significant hydrologic processes to variations of the groundwater quality at the study site.

Molecular evidence for the involvement of Anopheles nivipes (Diptera: Culicidae) in the transmission of Plasmodium falciparum in north-eastern India

The Anopheles philippinensis and An. nivipes mosquitoes that form part of the An. annularis species group are morphologically very similar and difficult to differentiate as adults. In consequence, researchers generally refer to all field-collected individuals of these species simply as the An. philippinensis-nivipes species complex. Although this species complex is understood to play a role in the transmission of parasites causing human malaria in north-eastern India, the identity of the exact species involved, and the relative importance of the local An. philippinensis and An. nivipes, are far from clear. To settle this issue, house-frequenting female adults of the An. philippinensis-nivipes species complex were collected from 23 localities in the six north-eastern states, identified to species (using an allele-specific PCR to explore the insects' ribosomal-DNA internal-transcribed-spacer-2 sequences) and checked for Plasmodium DNA (using a nested PCR based on the 18S subunit of the parasite's ribosomal DNA). Of the 337 females of the An. philippinensis-nivipes species complex that were investigated, 275 were identified as An. nivipes and 62 as An. philippinensis. Malarial infection was detected in the heads/thoraces of just two specimens, with P. falciparum DNA detected in one An. nivipes from Nagaland state and one An. nivipes from Assam state. These results provide unambiguous evidence of the presence of both An. philippinensis and An. nivipes in the north-eastern region of India and the involvement of An. nivipes in transmitting P. falciparum in this area.

Selective separation of radio-cesium from acidic solutions using supported liquid membrane containing chlorinated cobalt dicarbollide (CCD) in phenyltrifluoromethyl sulphone (PTMS)

A supported liquid membrane method was developed using chlorinated cobalt dicarbollide (CCD) in phenyltrifluoromethyl sulphone (PTMS) as the carrier, impregnated in PTFE flat sheet membranes for the selective separation of Cs(I) from nitric acid feed solution. Solvent extraction studies were carried out for optimizing the feed as well as strip conditions. >95% Facilitated transport of Cs(I) was observed in about 3h when 1M HNO(3) and 8M HNO(3) were used as the feed and strip solutions, respectively while 0.025M CCD in PTMS was used as the carrier extractant. Selectivity studies, carried out using a mixture of radiotracers viz. (51)Cr, (59)Fe, (99)Mo, (99m)Tc, (106)Ru, (137)Cs, (152)Eu and (241)Am, indicated selective transport of Cs(I) with DF values >100. Though reproducibility of the transport data was excellent when carried out in two successive transport experiments with freshly loaded carrier solvent, the stability of the membrane was poor which restricts its long term use.

Selective caesium transport using hollow fibre-supported liquid membrane containing calix[4]arene-bis-naphthocrown-6 as the carrier extractant

Polypropylene hollow fibre-based supported liquid membrane (HFSLM) containing calix[4]-bis-2,3-naphtho-crown-6 in 20% (v/v) n-dodecane+80% (v/v) 2-nitrophenyl octyl ether (NPOE) as the carrier solvent was employed for the first time to investigate the transport behaviour of radio-caesium. The carrier solution was 1 mM calix[4]-bis-2,3-naphtho-crown-6 in 20% (v/v) dodecane+80% (v/v) NPOE+0.4% alamine 336 and the feed was 3 M HNO3 while distilled water was used as the receiver phase. In spite of high viscosity of the carrier solvent, quantitative (>99%) transport was possible in about 6 h. Significant amount of acid transport was also noticed which was ascribed to a co-transport mechanism involving encapsulated hydronium ion. Selectivity studies were carried out by taking a mixture of radiotracers, viz. 51Cr, 59Fe, 85,89Sr, 137Cs, 152,154Eu and 241Am, which represent some of the elements present in the high level waste, in the feed solution. The decontamination factors for various metal ions were found to be in the range 540–890. High decontamination factors as well as possibility of working over several days without deterioration of the liquid membrane suggested possible application of the system for the recovery of radio-caesium from high level waste. Studies on the membrane stability indicated reproducible transport data over 40 h.

Development of tolerance of egg plant (Solanum melangena L.) to field application of dimethoate

Dimethoate, at field concentration (1.419 mg g(-1) fr wt), caused inhibition of photosynthesis, transpiration and stomatal conductance of Solanum melangena L. on first treatment but subsequent treatments caused adaptation and recovery of these parameters. The variable fluorescence (F(v)), dissipation (DI(0)/RC), 2 ms relative variable fluorescence (V(j)), net rate of PS II closure (M(0)), and maximum trapping rate of active PS II (TR(0)/RC) increased initially but reduced to the control value with repetition of treatment. However, fluorescence yield (TR(0)/Abs), electron transport probability (ET(0)/TR(0)) and activity of RC (ET(0)/RC) increased with each treatment. With each subsequent treatment there was enhancement of activities of esterases and decrease of insecticide content of leaves.