Ppm In Water Research Articles

Catalytic conversions in aqueous media: Part 3. Biphasic hydrogenation of polybutadiene catalyzed by Rh/TPPTS complexes in micellar systems

Water-soluble Rh/TPPTS complexes [TPPTS = P(C 6H 4- m-SO 3Na) 3] are active catalysts (TOF > 1200 h −1) for the biphasic hydrogenation of the completely water-insoluble heavy polybutadiene (PB) in single micelles formed by the cationic surfactant dodecyltrimethylammonium chloride (DTAC), or mixed micelles created by DTAC with either non-ionic or anionic surfactants. The reaction proceeds under mild conditions ( T = 100 °C, P H 2 = 20 bar ) at a molar ratio of P/Rh = 3 and C C units/Rh = 1000 within 20 min and at a rhodium concentration of only 10 ppm in water. The pH of the aqueous catalyst solution markedly influenced the activity. High catalytic activities were achieved under neutral conditions whereas at acidic or basic conditions the catalytic activity dramatically decreased. The hydrogenation rate depends critically on the microstructure of PB and the nature of micellar catalysis. The 1,4-units content of PB plays a major role for performing the catalytic hydrogenation reaction in single or mixed micellar systems for obtaining maximum reactivity. When the PB possesses a high 1,4-units content (98.0 wt% of 1,4-units and 2.0 wt% of 1,2-units) higher reaction rates were achieved in mixed micellar systems created by DTAC/Brij-35 surfactants compared to the rates observed in single DTAC micelles. In contrast, with PB starting material consisting of 61.0 wt% of 1,2-units and 39.0 wt% of 1,4-units higher reaction rates were obtained in single DTAC micelles compared to those rates achieved in mixed micellar systems.

Effects of Selenium and Low Levels of Lead on Mammary Tumor Development and Growth in MMTV-infected Female Mice

Selenium (Se) has been demonstrated in previous studies to inhibit mammary tumorigenesis in C3H mice infected with the murine mammary tumorvirus, MMTV. The antitumorigenic effects of Se in this animal model of breast cancer were subsequently shown to be counteracted by Se-antagonistic elements. Lead (Pb), for example, was found to abolish the anticarcinogenic effects of Se at 5 ppm in the drinking water. The present study was undertaken to explore the effects of Pb at just 0.5 ppm in the water, i.e., at a level comparable to the concentrations of Pb that have been measured in the tap water of older homes in some communities. Groups of 30 female virgin C3H/St mice infected with MMTV maintained on Torula yeast-based diets containing either 0.15 or 0.65 ppm of yeast-based organic Se and received either deionized water or water containing 0.5 ppm Pb as the acetate over their entire postweaning lifespan. In the control group on deionized water and the 0.15 ppm Se feed, the tumor incidence was 78.6%, which is normal for this strain. Increasing the Se content of the feed to 0.65 ppm lowered the tumor incidence to 30%, demonstrating the antitumorigenic effect of Se. In the experimental groups, the Pb-exposed mice on the 0.15 ppm Se feed developed signs of chronic Pb toxicity as evidenced by diminished weight gain that persisted up to the age of 10 months, during which period the animals remained tumor-free. Thereafter, weight gains ensued to near the values of the controls, and the tumors began to develop in rapid succession until the final tumor incidence of 73.7% was reached. In the group of mice on the 0.65 ppm Se feed, the toxic effects of Pb were diminished, as evidenced by the normal weight gains during the first 10 months but with concomitant physiological inactivation of Se, causing 82.6% of the mice to develop tumors, with the first tumor to appear at the age of 5 months, 7 months earlier than in the Pb-unexposed controls. In addition, tumor growth rates in this group were greatly accelerated and the survival of the tumor-bearing animals was significantly shortened. Direct evidence for the interactions of Pb with Se were obtained by determinations of the two elements in the livers, kidneys, and hair of tumor-free and tumor-bearing mice. However, the exposure of the mice to Pb in the water also altered the levels of Zn, Cu, Fe, and Cr in the organs and tissues, more so in tumor-bearing than tumor-free animals. The present study demonstrates the need to consider the interactions of Se with other trace elements in discussions of its mechanism of anticarcinogenic action.

New Approach in Filling of Fixed-Point Cells: Case Study of the Melting Point of Gallium

The typical way of constructing fixed-point cells is very well described in the literature. The crucible is loaded with shot, or any other shape of pure metal, inside an argon-filled glove box. Then, the crucible is carefully slid into a fused-silica tube that is closed at the top with an appropriate cap. After that, the cell is removed from the argon glove box and melted inside a furnace while under vacuum or filled with an inert gas like argon. Since the metal comes as shot, or in some other shape such as rods of various sizes, and takes more volume than the melted material, it is necessary to repeat the procedure until a sufficient amount of material is introduced into the crucible. With such a procedure, there is the possibility of introducing additional impurities into the pure metal with each cycle of melting the material and putting it back into the glove box to fill the cell. Our new approach includes the use of a special, so-called dry-box system, which is well known in chemistry. The atmosphere inside the dry box contains less than 20 ppm of water and less than 3 ppm of oxygen. Also, the size of the dry box allows it to contain a furnace for melting materials, not only for gallium but for higher-temperature materials as well. With such an approach, the cell and all its parts (pure metal, graphite, fused-silica tube, and cap) are constantly inside the controlled atmosphere, even while melting the material and filling the crucible. With such a method, the possibility of contaminating the cell during the filling process is minimized.

Monolayer-Based Selective Optical Recognition and Quantification of FeCl3 via Electron Transfer

Reagentless optical recognition and parts-per-million (ppm) quantification of FeCl3 in CH3CN was demonstrated using a redox-active Os(II)-chromophore-based monolayer on glass. The Fe3+-induced oxidation of the monolayer is fully reversible and can be monitored optically with a conventional UV/vis spectrophotometer (260-800 nm). The system can be reset with water within <1 min. Selectivity of the sensor toward FeCl3 is not affected by the presence of representative alkali metals, alkaline earth metals, and other transition-metal salts. Sensing of Fe3+ and concurrent generation of Fe2+ can be also observed with the naked eye by adding 2,2'-bipyridyl (bipy) to the solution to generate [Fe(bipy)3]2+. Validation of the analytical performance characteristics of the sensor was performed including reversibility, reproducibility, stability, and the detection range (0.5-162 ppm of FeCl3 in CH3CN, 100-1000 ppm in water). The monolayer is sensitive and specifically responsive to its target ion. In addition, a blind test was conducted to probe the reproducibility and reproducibility variances of the system. The reaction of the monolayer with a CH3CN solution containing 5 ppm of FeCl3 follows pseudo first-order kinetics in the monolayer with DeltaG298K = 21.6 +/- 0.1 kcal/mol, DeltaH = 10.2 +/- 1.5 kcal/mol, DeltaS = -38.3 +/- 4.9 eu.

Two simplified fluorescent staining techniques to observe infection structures of the oomycete Plasmopara viticola in grapevine leaf tissues

Plasmopara viticola, the causal agent of grapevine downy mildew, is an obligate biotrophic oomycete that grows in the intercellular spaces of host tissues and develops haustoria in the cells. Histological observations are the most effective methods to visualize and quantify the development of the infection structures. We chose two staining techniques leading to high resolution and contrast between parasite structures and host-plant tissues with a minimum of sample preparation: Blankophor and KOH-aniline blue fluorescent stainings. Blankophor (50 ppm in water or 15% KOH) staining was used to study the zoospore encystement on the leaf surface after release from sporangia. The aniline blue dye (0.05% in 0.067 M K 2HPO 4, pH 9–9.5, after hot KOH whitening) was used to observe the invasive structures inside host tissues that lead to the production of sporangiophores and infectious sporangia. We tested modifications of some parameters of the procedures to determine the most appropriate for high throughput analyses adapted to our pathosystem and equipment facilities.

Direct combination of immersed single‐drop microextraction with atmospheric pressure matrix‐assisted laser desorption/ionization tandem mass spectrometry for rapid analysis of a hydrophilic drug via hydrogen‐bonding interaction and comparison with liquid‐liquid extraction and liquid‐phase microextraction using a dual gauge microsyringe with a hollow fiber

This study presents the feasibility of direct coupling of the immersed single-drop microextraction (SDME) technique with atmospheric pressure matrix-assisted laser desorption/ionization mass spectrometry (AP-MALDI-MS) for the rapid analysis of a hydrophilic drug (dopamine) from aqueous solution and human urine in an ion trap tandem mass spectrometer through hydrogen-bonding interaction of dopamine with the extraction solvent (octanol). The optimum conditions for the SDME experiments coupled to AP-MALDI/MS were: stirring rate, 240 rpm; extraction time, 5 min; sample pH value, 8; and matrix concentration, 2000 ppm, using alpha-cyano-4-hydroxycinnamic acid (alpha-CHCA) as matrix. The limits of detection (LODs) for the SDME/AP-MALDI-MS experiments were 25 and 40 ppm in water and human urine, respectively. In a comparison of this method with the traditional liquid-liquid extraction (LLE), the SDME method shows better LODs than the LLE (40 ppm) and the same LODs (25 ppm) as the liquid-phase microextraction using a dual gauge microsyringe with a hollow fiber (LPME/DGM-HF). However, the SDME method is more convenient than the LPME/DGM-HF method.

The influence of water on deformation microstructures and textures in synthetic NaCl measured using EBSD

Wet NaCl with >10–15 ppm water shows weakening behaviour compared with dry NaCl containing <5 ppm of water. At strains greater than about 0.1 this weakening is associated with recrystallization but at lower strains there is also considerable weakening that is thought to be associated with pressure solution creep. The development of textures and microstructures in wet, synthetic NaCl polycrystals deformed at elevated temperatures has been investigated using electron backscattered diffraction (EBSD). At very low natural strains (0.07), textures, grain shapes and average misorientations of subgrain boundaries in wet NaCl differ to those found in dry NaCl deformed under similar conditions. In wet NaCl, cube shaped grains, oriented in a hard orientation for slip on the 〈110〉{110) system, grow and produce a well defined sub texture, with 〈100〉 poles at 45° to the compression axis. An estimation of strain in wet NaCl was made using average misorientation values of subgrain boundaries. We estimate about 55% of the total strain was accommodated by dislocation creep in wet NaCl at 0.07 strain, the remaining strain being accommodated by pressure solution. At higher strains dynamic recrystallization occurs forming a 〈100〉 fibre texture. This texture can be explained by preferential nucleation of initially strain free grains, which occurs after a critical strain in the most highly deformed, soft-orientation grains, that is grains which have 〈100〉 parallel to the compression axis.

Subacute administration of tributyltin chloride modulates neurotransmitters and their metabolites in discrete brain regions of maternal mice and their F1 offspring

Tributyltin (TBT) compounds have been used as anti-fouling agents and the central nervous system is one of its target organs. TBT-induced modulations of neurotransmitters in the brains of adult mice have been reported. However, little is known about the developmental neurotoxicity of TBT. In this study, we evaluated the effects of TBT on neurotransmitters and their metabolites in discrete brain regions of female ICR mice and their offspring. Pregnant ICR mice were exposed to TBT chloride at concentrations of 0, 15 or 50 ppm in water or 125 ppm in food. Male offspring were sacrificed at one, two and three weeks after birth. The concentrations of norepinephrine, dopamine (DA), dihydoxyphenylacetic acid, homovanillic acid (HVA), serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) were determined in different brain regions by HPLC. All offspring from the 125 ppm group died immediately after birth. A significant decrease in the body weight of the TBT-treated F1 groups compared to the control group was observed in the first week. Significant increases compared to the controls were observed for the DA concentration in the striatum of the 50 ppm F1 group, and for the HVA concentration in the cerebrum and the 5-HT concentration in the medulla oblongata of the 15 and 50 ppm F1 groups in the third week. At three weeks of age, the neurotransmitters and their metabolites may be useful indexes for developmental neurotoxicity. For the dams, a significant decrease in the 5-HT concentration was observed in the cerebellum, medulla, midbrain and striatum of the 125 ppm group compared to the control group. A significant decrease in the 5-HIAA concentration was also observed in the cerebellum, midbrain and striatum of the dams in the 125 ppm group compared to the control. TBT may induce a decrease in the synthesis of 5-HT in the dams. The discrepancy between dams and offspring may be due to several factors such as age, dose, route, sex and pregnancy.

Development of Visual Colorimetry for Formaldehyde in Water Based on Membrane Filtration and Its Application to Tap Water

A simple, rapid and low-cost method for the visual determination of formaldehyde in water based on the retention of two ion-associates on a membrane filter is proposed. Formaldehyde in water was reacted with 3-methyl-2-benzothiazolionone hydorazone (MBTH) to form an azine. The remaining MBTH was oxidized by ferric ion to form a light-yellow cation. The cation was reacted with the azine to form a deep-blue cation. Both blue and yellow cations were reacted with tetraphenylborate anion to form blue and yellow hydrophobic ion-associates, respectively. The ion-associates were retained on a membrane filter by filtration. The color of the filter was changed from yellow, green to blue, depending on the concentration of formaldehyde. The concentration was easily determined by comparing the color with those obtained from a series of standard solutions of formaldehyde. The formaldehyde from 0 to 0.07 ppm in water was determined with error less than ±0.01 ppm. Thirty minutes was enough for the entire analytical procedure. This method was successfully applied to tap-water samples spiked with formaldehyde. It will be useful for rapid judgment of a water sample to pass the quality standard for drinking water in Japan.

Effect of tributyltin compound onN-methyl-D-aspartate (NMDA) receptors in brain of preweanling mice

The aim of this study was to investigate the effect of tributyltin (TBT) compound onN-methyl-D: -aspartate (NMDA) receptors in the brains of preweanling mice. Pregnant ICR mice were exposed to TBT chloride at concentrations of 0, 15, and 50 ppm in water. Male offspring were sacrificed at 1, 2 and 3 weeks after birth. Mouse brain membranes were prepared from cerebral cortices, and the specific binding of [(3)H]MK-801 to an NMDA receptor was determined by radioligand binding assay. The mean body weight of preweanling mice of the 50 ppm dose group decreased by 17-25% (p<0.01) at 1, 2 and 3 weeks of age, compared with that of preweanling mice of the corresponding control group. The [(3)H]MK-801 binding level significantly decreased (p<0.05) in the 15 ppm F1 group at 1 week and in the 15 ppm and 50 ppm F1 groups at 3 weeks of age, compared with that in the corresponding control F1 group. The exposure to TBT via placenta and dam's milk seriously affected not only the growth of preweanling mice, but also the F1 cerebral NMDA receptors involved in memory and learning.

Catalytic oxidation of aliphatic chlorinated volatile organic compounds over Pt/H-BETA zeolite catalyst under dry and humid conditions

The present study investigated the applicability of noble metal/H-zeolite catalysts for the oxidative decomposition of chlorinated VOCs, and specifically compared the activity and selectivity of Pt/H-BETA with that of an H-BETA for the combustion of dichloromethane and trichloroethylene (1000 ppm in dry and humid air) between 200 and 550 °C at a space velocity of 15,000 h −1. A preliminary study identified the superior catalytic properties of H-BETA as an eventual support for a supported noble metal catalyst compared to other conventional supports such as Al 2O 3, ZrO 2 and SiO 2. The primary catalytic property for predicting activity in oxidative decomposition reactions was observed to be the total acidity of the support. Platinum played a major role in influencing the catalytic properties of H-BETA for complete oxidation of the chlorinated volatile organic compounds. Thus, the activity of the resultant Pt/H-BETA catalyst was noticeably enhanced, and the production of CO 2 and Cl 2, the products of CO oxidation and the Deacon reaction, respectively, was largely favoured. The addition of 15,000 ppm of water was found to improve the performance of the Pt/H-BETA catalyst, since the destruction temperatures were significantly lowered and the levels of molecular chlorine and chlorinated by-products were greatly reduced.

Efficacy of Chlorine Dioxide as a Gas and in Solution in the Inactivation of Two Trichothecene Mycotoxins

The efficacy of chlorine dioxide (ClO2) in detoxifying two potential bioterrorism agents, the trichothecene mycotoxins verrucarin A and roridin A, was evaluated. In the first experiment, verrucarin A (1, 5, or 10 microg) and roridin A (5 or 10 microg) were each inoculated onto square-inch sections of glass, paper, and cloth and exposed to 1000 ppm of ClO2 for either 24 or 72 h at room temperature. In the second experiment, verrucarin A and roridin A (1 or 2 ppm in water) were treated with 200, 500, or 1000 ppm ClO2 for up to 116 h at room temperature in light and dark conditions (N = 9 per treatment for test and control). A yeast assay using Kluyveromyces marxianuswas used to quantify the toxicity of verrucarin A and roridin A. Additionally, high-performance liquid chromatography was performed on selected samples. Results for the first experiment showed that ClO2 treatment had no detectable effect on either toxin. For the second experiment, both toxins were completely inactivated at all tested concentrations in as little as 2 h after treatment with 1000 ppm ClO2. For verrucarin A, an effect was seen at the 500 ppm level, but this effect was not as strong as that observed at the 1000 ppm level. Roridin A toxicity was decreased after treatment with 200 and 500 ppm ClO2, but this was not significant until the 24-h exposure time was reached. These data show that ClO2 (in solution) can be effective for detoxification of roridin A or verrucarin A at selected concentrations and exposure times.

Catalytic conversions in aqueous media: a novel and efficient hydrogenation of polybutadiene-1,4- block-poly(ethylene oxide) catalyzed by Rh/TPPTS complexes in mixed micellar nanoreactors

Exceptionally high catalytic activities (TOF > 840 h −1) were achieved in the aqueous phase hydrogenation of polybutadiene-1,4- block-poly(ethylene oxide) (PB- b-PEO) catalyzed by water-soluble Rh/TPPTS complexes [TPPTS = P(C 6H 4- m-SO 3Na) 3] in mixed micellar nanoreactors formed by dodecyltrimethylammonium chloride along with PB- b-PEO especially when n-hexane was added to the reaction system. This is the first example of a catalytic hydrogenation of an unsaturated polymer using water-soluble transition metal TPPTS complexes in aqueous media. Using Rh/TPPTS catalysts high activities were observed in the hydrogenation of PB- b-PEO in mixed micelles whereas in single micelles the activities were lower. Dynamic light scattering experiments showed the presence of mixed nanomicelles with smaller hydrodynamic radii compared to the radii of single micelles. A model of a mixed micellar nanoreactor was proposed to rationalize the observed results. The hydrogenation reaction was shown to be homogeneously catalyzed by Rh/TPPTS complexes generated in situ from RhCl 3·3H 2O and TPPTS under the reaction conditions. A recycling experiment showed that the catalytic activity remained high in a consecutive run even at a rhodium concentration of only 1 ppm in water.

Lightweight diode laser spectrometer CHILD (Compact High-altitude In-situ Laser Diode) for balloonborne measurements of water vapor and methane

A new lightweight near-infrared tunable diode laser spectrometer CHILD (Compact High-altitude In-situ Laser Diode spectrometer) was developed for flights to the stratosphere as an additional in situ sensor on existing balloonborne payloads. Free-air absorption measurements in the near infrared are made with an open-path Herriott cell with new design features. It offers two individual absorption path lengths optimized for CH4 with 74 m (136 pass) and H2O with 36 m (66 pass). New electronic features include a real-time gain control loop that provides an autocalibration function. In flight-ready configuration the instrument mass is approximately 20 kg, including batteries. It successfully measured stratospheric CH4 and H2O profiles on high-altitude balloons on four balloon campaigns (Environmental Satellite validation) between October 2001 and June 2003. On these first flights, in situ spectra were recorded from ground level to 32,000-m altitude with a sensitivity of 0.1 ppm [(parts per million), ground] to 0.4 ppm (32,000 m) for methane and 0.15-0.5 ppm for water.

Characterization of polyethersulfone hemodialysis membrane by ultrafiltration and atomic force microscopy

Hollow fiber membranes for hemodialysis were prepared from polyethersulfone (PES) and poly(vinyl pyrrolidone) (PVP) (PES/PVP=18/3 and 18/6 by weight) solution in N,N-dimethylacetamide by the dry wet spinning method. Hollow fibers were then heated either in hot water (95 °C for 30 min) or in air (150 °C for 5 min). These membranes were characterized by ultrafiltering dextrans of different molecular weights (200 ppm in water) at room temperature and an operating pressure of 5 psig. It was observed that the water flux of the hollow fiber increased significantly when heat-treated in water, while decreased when heat-treated in air. On the other hand, molecular weight cut-off (MWCO) of the hollow fiber increased slightly when heat-treated in water, while decreased drastically when heat-treated in air. The morphology of the surfaces of the hollow fibers was studied by atomic force microscope (AFM) in terms of surface roughness. The roughness of both inner and outer surface decreased upon heat-treatment, either heated in water or in air. The membrane heat-treated in air exhibited the lowest roughness parameter. SEM images also showed that the surface morphology of membranes was different before and after heat-treatment. Discussions are made on the basis of MWCO and AFM results. The performance data of the hollow fiber heated in air at 150 °C was found to be the most appropriate for hemodialysis application. The hollow fiber membrane prepared from the blend ratio of PES/PVP=18/3 showed slightly higher flux than the hollow fiber membrane prepared from a solution with PES/PVP ratio of 18/6.

Characterization of polyethersulfone hemodialysis membrane by ultrafiltration and atomic force microscopy

Hollow fiber membranes for hemodialysis were prepared from polyethersulfone (PES) and poly(vinyl pyrrolidone) (PVP) (PES/PVP=18/3 and 18/6 by weight) solution in N, N-dimethylacetamide by the dry wet spinning method. Hollow fibers were then heated either in hot water (95 °C for 30 min) or in air (150 °C for 5 min). These membranes were characterized by ultrafiltering dextrans of different molecular weights (200 ppm in water) at room temperature and an operating pressure of 5 psig. It was observed that the water flux of the hollow fiber increased significantly when heat-treated in water, while decreased when heat-treated in air. On the other hand, molecular weight cut-off (MWCO) of the hollow fiber increased slightly when heat-treated in water, while decreased drastically when heat-treated in air. The morphology of the surfaces of the hollow fibers was studied by atomic force microscope (AFM) in terms of surface roughness. The roughness of both inner and outer surface decreased upon heat-treatment, either heated in water or in air. The membrane heat-treated in air exhibited the lowest roughness parameter. SEM images also showed that the surface morphology of membranes was different before and after heat-treatment. Discussions are made on the basis of MWCO and AFM results. The performance data of the hollow fiber heated in air at 150 °C was found to be the most appropriate for hemodialysis application. The hollow fiber membrane prepared from the blend ratio of PES/PVP=18/3 showed slightly higher flux than the hollow fiber membrane prepared from a solution with PES/PVP ratio of 18/6.

Effect of Anticoccidials and Antibiotics on the Control of Blackhead Disease in Broiler Breeder Pullets

Broiler chicks inoculated with both Histomonas and cecal coccidia developed moderately severe blackhead disease. Antibiotics tested at normal feed or water additive levels had little effect on Histomonas lesions or weight gains. Bacitracin at 100, 200, or 300 g/ton reduced liver lesion scores (P < 0.05), but had no other positive effects. Apramycin at 300 ppm in water reduced liver lesion scores (P < 0.05), but did not improve cecal lesions or weight gains. Penicillin (100 ppm), chlortetracycline (100 ppm), tylosin (110 ppm), and sarafloxacin (40 ppm) in water did not improve liver or cecal blackhead lesions. Weight gains were improved relative to infected controls by treating with penicillin, tylosin, or sarafloxacin (P < 0.05).Five anticoccidials (salinomycin, diclazuril, nicarbazin, roxarsone, and lasalocid) were tested at common use levels in two trials. Results were similar in both trials; liver lesion scores in the nicarbazin treatment were reduced (P < 0.05) compared with controls and other medicated groups, and the number of birds positive for liver lesions was lower (P < 0.05). Otherwise, anticoccidials had no effect on liver or cecal lesion scores or weight gains. Control of coccidiosis by the anticoccidials (as shown by oocyst counts) varied among products but was not correlated with severity of blackhead lesions. These results suggest that the effect of cecal coccidia on susceptibility of chickens to Histomonas meleagridis is not a simple function of mechanical damage to the cecal mucosa.

Electrochemical monitoring of water–surfactant interactions in industrial lubricants

A few hundred ppm of water can cause detrimental changes in the lubricating properties of engine oil. Electrochemical sensors based on electrochemical impedance spectroscopy and cyclic voltammetry were utilized to detect water leaks and continuously monitor the time dependent dynamics of water–oil interactions following the injection of water into industrial lubricant. Immediately following the injection, water molecules interacted with the oil additives (surfactants) forming a water-in-oil emulsion based on inverse micelles. Emulsification was followed by gradual loss of water from the solution through evaporation and electrolysis. On-line data were used to characterize the dynamics of water micellization, evaporation, and electrolysis. The values of kinetic rate constants and diffusion coefficients for the components of the water/oil system were determined. In order to support the experimental data and establish the kinetics of water–oil interactions, literature equations describing these interactions were adopted to develop a computational analysis model. The model illustrated the processes occurring in the water/oil system and resulted in an increased understanding of the recorded experimental data.

Dealuminated Y Zeolites for Destruction of Chlorinated Volatile Organic Compounds

Chemical dealumination by (NH4)2SiF6 treatment has been investigated as an effective method for improving the catalytic behaviour of Y zeolites for chlorinated hydrocarbon combustion. Hence, the deep catalytic oxidation of dichloromethane (DCM), 1,2-dichloroethane (DCE), and trichloroethylene (TCE) was evaluated over two Y zeolites with different Si/Al ratios, at conditions of lean chlorocarbon concentration (around 1000 ppm) in dry and humid (15,000 ppm of water) air between 200 and 550°C. Catalyst-subjected to dealumination exhibited a higher activity in CVOC oxidation compared with that of the untreated one. The activity increase was attributed to the strong Brønsted acidic sites formed during catalyst dealumination. The ease of destruction was found to decrease in the following order: DCE>DCM>TCE. The main oxidation products formed were CO, CO2, HCl, and Cl2. In addition, some other chlorinated by-products/intermediates were detected, namely vinyl chloride, methyl chloride, and tetrachloroethylene in the oxidation of DCE, DCM, and TCE, respectively. The addition of water slightly diminished the zeolite activity and markedly changed the product distribution. Hence, by-product generation was found to be significantly reduced. Water also promoted somewhat the CO2 selectivity and led to complete reaction of chlorine to HCl by the Deacon reaction.

Effect of Polyacrylic Acid as Antiscaling Agent on Heat Exchangers

Polyacrylic acid (PAA) is synthesized from acrylic acid. Different concentrations ranging from 20 to 100 ppm of PAA in water are used as an antiscaling agent on copper and mild steel (m. s.) for 4 to 24 h. The deposition of salt decreases with increasing concentration of PAA as well as with increasing time. The zero acid value of PAA is observed after refluxing for 24 h. The concentration of PAA had no effect on the heat transfer coefficient and the heat transfer rate of the shell and tube heat exchanger. When varying the amount of PAA from 20 to 100 ppm in water, a negligible change in viscosity is observed which does not effect the flow behaviour of water in heat exchanger.