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Kinds of Contact Time Selected AbstractsNi2+ removal from aqueous solutions using conditioned clinoptilolites: Kinetic and isotherm studiesENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2009Semra Çoruh Abstract The aim of this study is to investigate the effects of conditioning with NaCl and HCl solutions on removal of Ni2+ ions from aqueous solutions using natural clinoptilolite. Batch studies were performed to evaluate the effects of various parameters such as chemically conditioning, adsorbent amount, contact time, initial pH of the solution, mixing temperature, and initial metal ions. The results clearly showed that the conditioning improved both the exchange capacity and the removal efficiency. Langmuir, Freundlich, Temkin, and Dubinin-Kaganer-Radushkevich (DKR) isotherm models were adopted to describe the adsorption isotherms. Adsorption isotherms of Ni2+ ions could be best modeled by Langmuir equation. Three simplified models including pseudo-second-order, intraparticle diffusion and Elovich were used to test the adsorption kinetics. These results indicate a significant potential for the natural and conditioned clinoptilolites as an adsorbent/ion-exchange material for heavy metal removal. © 2008 American Institute of Chemical Engineers Environ Prog, 2009 [source] Performance of a full-scale biotrickling filter treating H2S at a gas contact time of 1.6 to 2.2 secondsENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 2 2003David Gabriel Emission of objectionable odors is a major problem for wastewater treatment and other processing facilities. Biological treatment is a promising alternative to conventional control methods, such as chemical scrubbing, but historically, biotreatment has always required significantly larger reactor volumes than chemical scrubbers. In this paper, we present several aspects of the operation and performance of a chemical scrubber, retrofitted to operate as a biotrickling filter treating 16,000 m3 h,1 of foul air with the original gas contact time of 1.6 to 2.2 seconds. In continuous operation for more than a year, the biotrickling filter has shown stable performance and robust behavior for H2S treatment, with pollutant removal performance comparable to using a chemical scrubber. Reclaimed water was used as a nutrient source for the process, and to maintain the pH in the biotrickling filter between 1.5 and 2.2. At a gas contact time of 1.6 seconds, H2S removal was in excess of 95% for sustained inlet H2S concentrations as high as 30 ppmv. This corresponds to volumetric elimination rates of 95 to 105 g H2S m,3 h,1. Efficiencies of about 90% were observed under transient conditions at 2.2 seconds gas contact time for inlet concentration peaks up to 60 ppmv. The biotrickling filter also removed significant amounts of reduced sulfur compounds, ammonia, and volatile organic compounds present in traces in the air, which is important in practical applications. Selected experiments, such as intermittent trickling operation and a one-month operation period at neutral pH, are also presented. Results indicate that the intermittent trickling operation does not have a significant effect on H2S removal. However, when operated at neutral pH, biotrickling filter performance clearly decreased, probably due to an excessive chlorine supply to the reactor through the make-up water. The study demonstrates that biotrickling filters can replace chemical scrubbers as a safer, more economical technique for odor control. [source] Slow desorption behavior of one highly resistant aromatic amine in Lake Macatawa, Michigan, USA, sedimentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 12 2005Shihua Chen Abstract The desorption behavior of benzidine from Lake Macatawa (Holland, MI, USA) sediment was investigated in this study using batch solvent extraction method. Seven solvents were tested as the extracting reagents: Deionized water (DI), calcium chloride in DI (CaCl2), sodium hydroxide in DI (NaOH), acetonitrile (ACN), a mixture of acetonitrile and ammonium acetate in DI (ACNNH4OAc), methanol (MeOH), and hydrochloric acid in DI (HCl). These solvents are proposed to react with sediment-associated benzidine by different mechanisms (e.g., cation exchange, hydrophobic partitioning, and covalent binding). Three sets of sorption isotherm experiments were conducted separately in these seven solvents with a 7-d, three-week, and two-month contact time. The results demonstrated nonlinear isotherms with Freundlich 1/n values varying from 0.25 to 0.52. The desorption behavior of benzidine in the solvents was evaluated after the sorption of benzidine onto the sediment with same contact times of 7 d, three weeks, and two months. A two-stage model subsequently was applied to simulate the experimental data. The rapidly desorbing rate constants were on the order of one to two per day for ACN, ACN-NH4OAc, and NaOH solvents, and the slowly desorbing rate constants were on the order of 10,5 to 10,4/d. Sequential desorption experiment demonstrated low total extraction efficiency of less than 40%. Both the observed sorption and desorption phenomena suggested that hysteresis and/or mass-transfer limited diffusion may result in the slow desorption behavior observed in this study. [source] Enhanced external counterpulsation improves skin oxygenation and perfusionEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 6 2004M. J. Hilz Abstract Background, Enhanced external counterpulsation (EECP) augments diastolic and reduces systolic blood pressures. Enhanced external counterpulsation has been shown to improve blood flow in various organ systems. Beneficial effects on skin perfusion might allow EECP to be used in patients with skin malperfusion problems. This study was performed to assess acute effects of EECP on superficial skin blood flow, transdermal oxygen and carbon dioxide pressures. Materials and methods, We monitored heart rate, blood pressure, transdermal blood flow as well as oxygen and carbon dioxide pressures in 23 young, healthy persons (28 ± 4 years) and 15 older patients (64 ± 7 years) with coronary artery disease before, during and 3 min after 5 min EECP. Friedman test was used to compare the results of 90-s epochs before, during and after EECP. Significance was set at P < 0·05. Results, Enhanced external counterpulsation increased heart rate and mean blood pressure. During EECP, transdermal oxygen pressure and concentration of moving blood cells increased while transdermal carbon dioxide pressure and velocity of moving blood cells decreased significantly in both groups. After EECP, transdermal carbon dioxide pressure was still reduced while the other parameters returned to baseline values. Conclusions, Improved skin oxygenation and carbon dioxide clearance during EECP seem to result from the increased concentration and reduced flow velocity, i.e. prolonged contact time, of erythrocytes. The increased concentration of moving blood cells and the decreased velocity of moving blood cells at both tested skin sites indicate peripheral vasodilatation. [source] Optimization of activated carbon-based decontamination of fish oil by response surface methodologyEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 7 2007Åge Oterhals Abstract The effect of activated carbon (AC) adsorption on the reduction of persistent organic pollutants (POP) in fish oil was studied based on response surface methodology at a 5-g/kg AC inclusion level. Pretreatment of the oil by alkali refining and bleaching increased the POP levels. The tested process variables (contact time and temperature) affected the AC adsorption rate and significant first- and second-order response models could be established. Polychlorinated dibenzo- p -dioxins and dibenzofurans (PCDD/F) showed a very rapid adsorption behavior and the concentration and toxic equivalent (TEQ) level could be reduced by 99%. Adsorption of dioxin-like polychlorinated biphenyls (DL-PCB) was less effective and depended on ortho substitution, i.e. non- ortho PCB were adsorbed more effectively than mono- ortho PCB with a maximum of 87 and 21% reduction, respectively, corresponding to a DL-PCB-TEQ reduction of 73%. A common optimum for both PCDD/F and DL-PCB adsorption could not be identified. AC treatment had no effect on the level of polybrominated diphenyl ether flame retardants. The differences in adsorption patterns may be explained based on molecular conformation. No change in oil quality could be observed based on oxidation parameters. Compliance with present PCDD/F and DL-PCB legislation levels in fish oil can be achieved based on AC adsorption. [source] Supercritical carbon dioxide extraction of 2-acetyl-1-pyrroline and volatile components from pandan leavesFLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2004Natta Laohakunjit Abstract The ,avour of pandan (Pandanus amaryllifolius Roxb.) leaves was extracted by supercritical ,uid with CO2 (SC-CO2) under different conditions of pressure, temperature and contact time to determine the yield of 2-acetyl-1-pyrroline (ACPY) and various other components; 14 volatile compounds on the gas chromatogram were identi,ed, and the predominant constituents were ACPY and 3-methyl-2(5H)-furanone. The interaction of different conditions signi,cantly in,uenced the yield of ACPY and various volatile compounds. There is a potential for high yield of ACPY by SC-CO2 at 200 bar, 500 °C and 20 min. The SDE,ether extract was found to have a very small amount of ACPY and an undesirable odour, as compared to the dark green ethanol extract, which contains a relatively larger quantity of ACPY and even more 3-methyl-2(5H)-furanone. Although at least 34 new components were uncovered from SC-CO2, SDE, and ethanol extraction, both ACPY and 3-methyl-2(5H)-furanone were the components tentatively obtained by all three methods. Copyright © 2004 John Wiley & Sons, Ltd. [source] Bentonite as a Natural Adsorbent for the Sorption of Iron from the Ground Water Exploited from Aswan Area, EgyptGROUND WATER MONITORING & REMEDIATION, Issue 1 2004Gharib M. Taha Sorption of dissolved Fe2+ on bentonite was studied using a batch technique. The distribution coefficient, Kd, was evaluated for a bentonite-iron system as a function of contact time, pH, sorbent and sorbate concentrations, and temperature. Sorption results were interpreted in terms of Freundlich's and Langmuir's equations. Thermodynamic parameters for the sorption system were determined at three temperatures: 298°, 308°, and 318°K. The values of ,H°(-4.0 kjmol,1) and ,G°(-2.46 Kjmol,1) at 298°K (25°C) suggest that sorption of iron on bentonite is an exothermic and a spontaneous process. The ,G° value became less negative at higher temperatures and, therefore, less iron was sorbed at higher temperatures. The desorption studies with 0.01M CaCl2 and deionized water at iron loading on bentonite showed that more than 90 wt% of the iron is irreversibly sorbed, probably due to the fixation of the iron by isomorphous replacement in the crystal lattice of the sorbent. [source] Effects of operating conditions on infiltration of molten aluminum and heat transfer in a centrifugal force fieldHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 6 2003Qinwei Tian Abstract This paper presents the results of an analysis aimed at determining the influence of changing operating conditions in the centrifugal infiltration casting. It considers the effect of centrifugal force on infiltration and heat transfer. The molten aluminum flow with heat transfer though SiC porous media in a centrifugal force field is described using a mathematical and physical model by employing the local thermal nonequilibrium between the solid and fluid phases. The calculation results show that the temperature difference between molten aluminum and SiC porous media in the infiltrated region decreases with the contact time. There are two distinctly noticeable stages of infiltration velocity: the onset stage of infiltration, which drops down sharply, and the following stage of smooth velocity. The operating conditions have important effects on the infiltration velocity and temperature patterns of fluid and solid. A suitable rotational speed and SiC volume fraction should be chosen to ensure the flow of molten metal in the porous preform and diminish the temperature difference between fluid and solid. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(6): 501,510, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10114 [source] Characterization of CD4+ T-cell,dendritic cell interactions during secondary antigen exposure in tolerance and primingIMMUNOLOGY, Issue 4 2009Catherine M. Rush Summary Despite the recent advances in our understanding of the dynamics of the cellular interactions associated with the induction of immune responses, comparatively little is known about the in vivo behaviour of antigen-experienced T cells upon secondary antigen exposure in either priming or tolerance. Such information would provide an insight into the functional mechanisms employed by memory T cells of distinct phenotypes and provide invaluable knowledge of how a specific tolerogenic or immunogenic state is maintained. Using real-time imaging to follow the in vivo motility of naïve, primed and tolerized CD4+ T cells and their interactions with dendritic cells (DCs), we demonstrate that each of these distinct functional phenotypes is associated with specific patterns of behaviour. We show that antigen-experienced CD4+ T cells, whether primed or tolerized, display inherently slower migration, making many short contacts with DCs in the absence of antigen. Following secondary exposure to antigen, primed T cells increase their intensity or area of interaction with DCs whereas contacts between DCs and tolerized T cells are reduced. Importantly, this was not associated with alterations in the contact time between DCs and T cells, suggesting that T cells that have previously encountered antigen are more effective at surveying DCs. Thus, our studies are the first to demonstrate that naïve, primed and tolerized T cells show distinct behaviours before and after secondary antigen-encounter, providing a novel mechanism for the increased immune surveillance associated with memory T cells. These findings have important consequences for many immunotherapeutics, which aim to manipulate secondary immune responses. [source] Peracetic acid as an alternative wastewater disinfectant to chlorine dioxideJOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2002S. Stampi Aims: The aim of this study was to compare the efficiency of peracetic acid with that of chlorine dioxide in the disinfection of wastewater from a sewage treatment plant (serving about 650 000 inhabitants) that has been using peracetic acid as a disinfectant since 1998. Methods and Results: A total of 23 samplings were made, each consisting of three samples: from secondary effluent, effluent disinfected with 2 mg l,1 of peracetic acid and effluent disinfected with 2·2 mg l,1 of chlorine dioxide (contact time 20 min). For each sample, measurements were made of the heterotrophic plate count at 36°C, total and faecal coliforms, Escherichia coli, enterococci, pH, suspended solids and chemical oxygen demand (COD). During the first phase of the experiment the peracetic acid was seen to be less efficient than chlorine dioxide. To improve the disinfectant action a system of mechanical agitation was added which led to a greater efficiency in the inactivation of bacteria of faecal origin. Conclusions: Both products were found to be influenced by the level of microbial contamination, the amount of suspended solids and COD but not by the pH of the effluent before disinfection. The immediate mixing of the wastewater and disinfectant caused a greater reduction in enterococci. Significance and Impact of the Study: Since peracetic acid was seen to produce a high abatement of micro-organisms, it can be considered as a valid alternative to chlorine dioxide in the disinfection of wastewaters. [source] Preparation and characterization of polyalginate,glutaraldehyde membranes,Swelling analysis by microcalorimetry and adsorption kinetics of cationic dyeJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2010Eunice F. S. Vieira Abstract Thin crosslinked polyalginate,glutaraldehyde membranes were prepared and characterized by Fourier-transformed infrared spectroscopy, thermal analysis (TG/DTG), and X-ray diffractometry. Microcalorimetric analyses have pointed out that water swellings of the membranes are slightly exothermic, and the swelling energies decrease with increasing temperature. The membranes were tested for the adsorption of methylene blue (MB) dye from aqueous solutions. The adsorption capacity of the membranes increased with increasing initial MB concentration and decreased with increasing temperature. It was observed that the MB adsorption kinetic data were best fitted by the Avrami model. Intraparticle diffusion of MB into the interior of the membranes was detected after 60 min of contact time. The MB adsorption on the membranes was also evaluated by three new 22 full factorial designs (36 experiments). It was found that binary interactions between initial dye concentration and temperature are statistically important for MB adsorption on the membranes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Adsorption of Hg2+ on a novel chelating fiber prepared by preirradiation grafting and aminationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2009Ying Yang Abstract A novel chelating fiber was prepared by the irradiation-induced grafting copolymerization of glycidyl methacrylate on polypropylene fiber and consequent amination with diethylenetriamine. The effects of the reaction conditions, such as reaction time, temperature, and monomer concentration, on the degree of grafting were investigated. The optimal conditions for grafting were found to be 3 h, 100°C, and a 50% (v/v) glycidyl methacrylate concentration in tetrahydrofuran solution. This fiber showed good adsorption performance at different concentrations of Hg2+, in particular for trace Hg2+. Under the adsorption conditions of pH = 4, initial concentration = 1000 mg/L, and time = 20 h, the adsorption capacity of the chelating fiber for Hg2+ reached 785.28 mg/g. It completely adsorbed the Hg2+ ions in solution within a short contact time, showing a very high adsorption rate for Hg2+. Furthermore, the chelating fiber also had a high selectivity for mercury, whereas Cu2+ coexisted in different concentrations. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Sorption properties of the iminodiacetate ion exchange resin, amberlite IRC-718, toward divalent metal ionsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2008Charef Noureddine Abstract The sorption properties of the commercially available cationic exchange resin, Amberlite IRC-718, that has the iminodiacetic acid functionality, toward the divalent metal-ions, Fe2+, Cu2+, Zn2+, and Ni2+ were investigated by a batch equilibration technique at 25°C as a function of contact time, metal ion concentration, mass of resin used, and pH. Results of the study revealed that the resin exhibited higher capacities and a more pronounced adsorption toward Fe2+ and that the metal-ion uptake follows the order: Fe2+ > Cu2+> Zn2+ >Ni2+. The adsorption and binding capacity of the resin toward the various metal ions investigated are discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Adsorptive removal of textile dyes from aqueous solutions by dead fungal biomassJOURNAL OF BASIC MICROBIOLOGY, Issue 1 2006Dilek Asma Dead fungal biomass prepared from Phanerochaete chrysosporium and Funalia trogii was tested for their efficiency in removal of textile dyes. The effects of contact time, initial dye concentration, amount of dead biomass and agitation rate on dye removal have been determined. Removal of all dyes required a very short time (60 min). Experimental results show that, P. chrysosporium was more effective than F. trogii . An increase in the amount of dead biomass positively affected of the dye removal. The removal efficiency of different amount of biomass was in order 1 g > 0.5 g > 0.2 g > 0.1 g. The highest removal was obtained at 150,200 rpm. Slightly lower removing activities were found at lower agitation rates. This study showed that it was possible to remove textile dyes by dead biomass of P. chrysosporium . (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Extraction of alcohol using emulsion liquid membrane consisting of paraffin oil as an organic phase and lecithin as a surfactantJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2010B.S. Chanukya Abstract BACKGROUND: This paper reports on the use of a liquid emulsion membrane involving paraffin light oil as membrane phase and lecithin as surfactant for the extraction of alcohol from anthocyanin extract and simulated pineapple wine. RESULTS: The extraction of alcohol was found to depend on the many factors such as surfactant concentration, contact time, stirring speed, stirring time, and ratio of membrane emulsion to feed volume. Results showed that optimum conditions for maximum alcohol extraction (25%) were lecithin concentration 3%, contact time 20 min, stirring speed 250 rpm and ratio of membrane emulsion to feed volume 1:2. Multistage extraction using this liquid emulsion membrane was found to completely remove alcohol from anthocyanin extract and from simulated pineapple wine in seven stages and five stages, respectively. CONCLUSION: This liquid emulsion membrane was found to be a useful method for the extraction of alcohol from aqueous feed. Copyright © 2009 Society of Chemical Industry [source] Behaviour and mechanism of Zn(II) adsorption on Chinese loess at dilute slurry concentrationsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2008Xiaowu Tang Abstract BACKGROUND: Zn(II) is commonly present in mining drainage in developing countries. Since loess is abundant and always located near mining sites in China, it would be useful to investigate the possibility and efficiency of using loess to remove Zn(II) from aqueous solution. RESULTS: The Zn(II) adsorption capacity of Chinese loess was determined as 215.9 mg g,1. The adsorption followed pseudo-second-order kinetics and took place mainly by surface diffusion. Generally, higher initial pH and solute concentration resulted in higher % Zn(II) removal, while higher temperature and slurry concentration led to lower % Zn(II) removal. A thermodynamic study revealed that the adsorption process was exothermic, with the predicted enthalpy change ranging from ,20.87 to ,4.06 kJ mol,1. With the assistance of X-ray photoelectron spectroscopy and X-ray diffraction, the high adsorption capacity was ascribed to the growth of micro-organisms and mineral constituents such as kaolinite and goethite. CONCLUSION: Chinese loess proved effective for Zn(II) adsorption in this study. The optimal adsorption conditions included pH > 3.0, temperature ,15 °C and contact time , 400 min. As an abundant natural soil in arid areas with very low population density, it would be appropriate to develop this material into a wastewater-purifying agent. Copyright © 2008 Society of Chemical Industry [source] A modified cellulose adsorbent for the removal of nickel(II) from aqueous solutionsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2006David W O'Connell Abstract A series of adsorption studies was carried out on a glycidyl methacrylate- modified cellulose material functionalised with imidazole (Cellulose- g -GMA-Imidazole) to assess its capacity in the removal of Ni(II) ions from aqueous solution. The study sought to establish the effect of a number of parameters on the removal of Ni(II) from solution by the Cellulose- g -GMA-Imidazole. In particular, the influence of initial metal concentration, contact time, solution temperature and pH were assessed. The studies indicated a Ni(II) uptake on the Cellulose- g -GMA-Imidazole sorbent of approximately 48 mg g,1 of nickel from aqueous solution. The adsorption process fitted the Langmuir model of adsorption and the binding process was mildly endothermic. The kinetics of the adsorption process indicated that nickel uptake occurred within 400 min and that pseudo-second order kinetics best describe the overall adsorption process. Nickel(II) adsorption, recovery and re-adsorption studies indicated that at highly acidic pH values the adsorbent material becomes unstable, but in the range pH 3,6, the adsorbent is stable and shows limited but significant Ni(II) recovery and re-adsorption capability. Copyright © 2006 Society of Chemical Industry [source] Comparative studies of Oryza sativa L. husk and chitosan as lead adsorbentJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2006Mohamed Mohamed Daud Zulkali Abstract The adsorption capacity of two low-cost adsorbents, Oryza sativa L. husk and chitosan, was studied. Lead solution was used as the adsorbate. The effect of initial lead concentration, pH, temperature, weight of adsorbent, particle size and contact time on lead uptake was investigated. It was found that the isotherm data were well described by the Freundlich isotherm for both adsorbents. The adsorption capacities of rice husk and chitosan were 5.69 and 8.31 mg g,1, respectively. It was shown that chitosan was more effective than rice husk. Copyright © 2005 Society of Chemical Industry [source] Glucoraphanin extraction from Cardaria draba: Part 1.JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2005Optimization of batch extraction Abstract Glucosinolates have historically been considered an anti-nutritional component of food and feed cereal crops. Large-scale protocols have been aimed at complete glucosinolate elimination from plants, rather than maximizing the recovery of any particular glucosinolate compound. Recently, glucoraphanin, an alkenyl glucosinolate, has been found to have nutritional value in terms of anti-carcinogenic behavior and hypertension relief. In this work, we report on the efficient capture of glucoraphanin from the noxious weed Cardaria draba. The effect of temperature, ethanol content in the aqueous solvent, initial solvent pH, solids loading, and contact time on both glucoraphanin and glucosinalbin recovery were examined. The optimal extraction conditions, evaluated using 0.11 dm3 stirred baffled vessels, were found to be 20% aqueous ethanol solvent at 70 °C and an initial pH value of 3, extracted at a solid to liquid ratio of 50 g dm,3 over 20 mins. The recovery achieved with the baffled vessels was up to three times greater than the glucoraphanin yield obtained using standard analytical procedures that involved the use of 8.0 × 10,3 dm3 of hot, 80% ethanol solutions in test tubes at the same solvent loading. This corresponds to 30 mg g,1 of glucoraphanin recovered from the dried C draba leaves, versus only 10 mg g,1 using the analytical method. Copyright © 2005 Society of Chemical Industry [source] Disinfection of recycled red-meat-processing wastewater by ozoneJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2005Jiangning Wu Abstract Ozonation of a real red-meat-processing wastewater was conducted in a semi-batch reactor to explore the possibility of the water reuse. The experimental results revealed that ozone was very effective in disinfection of the red-meat-processing wastewater. After 8 min of ozonation with an applied ozone dose of 23.09 mg min,1 liter,1 of wastewater, 99% of aerobic bacteria, total coliforms and Escherichiacoli were inactivated. Empirical models were developed to predict the microbial inactivation efficacy of ozone from the CT values for the real red-meat-processing wastewater. A correlation was also derived to estimate the CT values from the applied ozone dose and the ozone contact time. The results also revealed that under the ozonation condition for 99% inactivation of aerobic bacteria, total coliforms and E coli, the decrease in the chemical oxygen demand and the 5-day biological oxygen demand of the wastewater were 10.7% and 23.6%, respectively. However, ozonation under this condition neither improved the light transmission nor reduced the total suspended solids (TSS) despite of the decolorization of the wastewater after ozonation. Copyright © 2005 Society of Chemical Industry [source] Separation of cobalt and nickel from acidic sulfate solutions using mixtures of di(2-ethylhexyl)phosphoric acid (DP-8R) and hydroxyoxime (ACORGA M5640)JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2004Arisbel Cerpa Abstract DP-8R and ACORGA M5640 extractants diluted in Exxsol D100 were used to co-extract cobalt and nickel from aqueous acidic sulfate media. The influences of equilibration time, temperature, equilibrium pH and reagent concentrations on the extraction of both metals have been studied. It was observed that both cobalt and nickel extraction are slightly sensitive to temperature but are pH dependent. Metal extraction equilibria are reached within about 5 min contact time. In addition, cobalt extraction depends on the extractant concentration in the organic phase. For a solution containing 0.5 g dm,3 each of cobalt and nickel and an initial pH of 4.1, conditions were established for the co-extraction of both metals and selective stripping (with H2SO4) of cobalt and nickel. Using the appropriate reagent concentrations the yield (extraction stage) for both metals exceeded 90%, and stripping of cobalt and nickel was almost quantitative. Copyright © 2004 Society of Chemical Industry [source] Chromatographic partitioning of cesium by a macroporous silica-calix[4]arene-crown supramolecular recognition compositeAICHE JOURNAL, Issue 10 2010Anyun Zhang Abstract A macroporous silica-based 1,3-[(2,4-diethyl-heptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14) supramolecular recognition polymeric composite, (Calix[4]+Oct)/SiO2 -P, was synthesized. It was performed by impregnating and immobilizing Calix[4]arene-R14 and n -octanol into the pores of the macroporous SiO2 -P particles support. n -Octanol was used to modify Calix[4]arene-R14 through hydrogen bonding. The effect of eight typical fission products contained in highly active liquid waste (HLW) on the adsorption of Cs(I), one of the heat generators, was investigated at 298 K by examining the effect of contact time and the HNO3 concentration in a range of 0.3,7.0 M. (Calix[4]+Oct)/SiO2 -P showed excellent adsorption ability and high selectivity for Cs(I) at 4.0 M HNO3 over the tested elements. The partitioning of Cs(I) from a simulated HLW was operated by (Calix[4]+Oct)/SiO2 -P packed column. Cs(I) was able to be effectively eluted by water and separated from the tested metals. It is demonstrated that (Calix[4]+Oct)/SiO2 -P is promising to apply in chromatographic separation of Cs(I) from HLW. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] A comparative adsorption study of copper on various industrial solid wastesAICHE JOURNAL, Issue 10 2004Archana Agrawal Abstract The adsorption behavior of Cu on three solid waste materials,sea nodule residue (SNR), fly ash (FA), and red mud (RM),was investigated. The effects of various parameters, such as pH of the feed solution, contact time, temperature, adsorbate and adsorbent concentration, and particle size of the adsorbent, were studied for optimization of the process parameters. Adsorption of copper increased with increasing time, temperature, pH, and adsorbate concentration, and decreased with increasing initial copper concentration. The equilibrium data fit well with the Langmuir and Freundlich isotherms in the case of SNR, but not on RM and FA, because there was no appreciable effect of temperature on the metal removal on these two adsorbents. The adsorption of copper on SNR followed first-order kinetics involving the surface complex formation mechanism on the charged surface. Under the optimized conditions the adsorption capacity for copper was found to be 19.65 mg/g of SNR, 1.98 mg/g of FA, and 2.28 mg/g of RM. Thus the adsorption capacity of SNR was found to be more than that of activated carbon, thus making it suitable for the treatment of industrial effluents to reduce the level of copper within the permissible limits for its land disposal (3 mg/L) according to ISI guidelines. © 2004 American Institute of Chemical Engineers AIChE J 50: 2430,2438, 2004 [source] Millisecond catalytic wall reactors: I. Radiant burnerAICHE JOURNAL, Issue 5 2001J. M. Redenius Short-contact-time reactors have potential for high throughput in reactors much smaller than their traditional counterparts. While they operate adiabatically, heat can be exchanged at short contact time by integrating heat exchange into the reactor. Hot effluent of exothermic reaction systems can be redirected over feed gases to recuperate a portion of the sensible heat. Placing catalyst directly on reactor walls eliminates the resistance to heat transfer in the thermal boundary layer so that heat released by combustion can be effectively coupled to an emitter, such as in a radiant burner. A radiant heater was constructed, operated, and simulated incorporating short contact time, energy recuperation, and a catalytic wall. This burner operated stably for many hours at a firing rate from ,50 to > 160 kW/m2 at a radiant temperature of 950 to 1,150 K at a radiant efficiency of ,60% with a residence time in the reacting zone of ,10 ms. This reactor was modeled using 2-D Navier-Stokes equations including detailed models for chemistry and heat transport. Temperature and compositions predicted agreed well with experimental measurements. [source] Monolithic Ceramic Foams for Ultrafast Photocatalytic Inactivation of BacteriaJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2009Pinggui Wu Palladium-modified nitrogen-doped titanium dioxide (TiON/PdO) foams were synthesized by a sol,gel process on a polyurethane foam template. The TiON/PdO foam was tested for microbial killing using Escherichia coli cells as a target. Under visible-light illumination, the TiON/PdO foam displayed a strong antimicrobial effect on the bacteria cells in water. The antimicrobial effect was found to be dependent on the palladium content and the calcination temperature. In a flow-through dynamic photoreactor, the new photocatalyst efficiently inactivated E. coli within a short contact time (<1 min), the shortest ever reported for the photocatalytic killing of bacteria. The strong antimicrobial functions of the TiON/PdO foam were related to charge trapping by PdO and the high contact efficiency of the foam structure. [source] INTEGRATED MANAGEMENT OF IN-FIELD, EDGE-OF-FIELD, AND AFTER-FIELD BUFFERS,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 1 2006Seth M. Dabney ABSTRACT: This review summarizes how conservation benefits are maximized when in-field and edge-of-field buffers are integrated with each other and with other conservation practices such as residue management and grade control structures. Buffers improve both surface and subsurface water quality. Soils under permanent buffer vegetation generally have higher organic carbon concentrations, higher infiltration capacities, and more active microbial populations than similar soils under annual cropping. Sediment can be trapped with rather narrow buffers, but extensive buffers are better at transforming dissolved pollutants. Buffers improve surface runoff water quality most efficiently when flows through them are slow, shallow, and diffuse. Vegetative barriers - narrow strips of dense, erect grass - can slow and spread concentrated runoff. Subsurface processing is best on shallow soils that provide increased hydrologic contact between the ground water plume and buffer vegetation. Vegetated ditches and constructed wetlands can act as "after-field" conservation buffers, processing pollutants that escape from fields. For these buffers to function efficiently, it is critical that in-field and edge-of-field practices limit peak runoff rate and sediment yield in order to maximize contact time with buffer vegetation and minimize the need for cleanout excavation that destroys vegetation and its processing capacity. [source] Bactericidal effect of chlorine on Mycobacterium paratuberculosis in drinking waterLETTERS IN APPLIED MICROBIOLOGY, Issue 3 2001L.B. Whan Aims:,One possible route of transmission of Mycobacterium paratuberculosis from cattle to humans is via contaminated water supplies. The aim of this work was to determine whether this organism can survive standard water treatment processes. Methods and Results:,Two strains of M. paratuberculosis (bovine strain, NCTC 8578 and human strain Linda, ATCC 43015) were subjected to various chlorine concentrations (0·5, 1·0 and 2·0 ,g ml,1) for 15 and 30 min. Chlorine test solutions were made up in two types of water, sterile water that had been deionized and subjected to reverse osmosis (DRO) and DRO water containing MgCl2, CaCl2, NaHCO3 and bovine serum albumin (0·3% w/v), the latter to mimic conditions the organism would experience in commercial water treatment operations. Conclusions:,The data showed that when initial inoculum levels were high (106 cfu ml,1) neither M. paratuberculosis strain was completely killed at the free chlorine concentrations and contact times applied. Log10 reductions in the range 1·32,2·82 were observed. The greatest log10 reduction in cell numbers (2·82 and 2·35 for the bovine and human strains, respectively) was observed at the highest chlorine concentration (2 ,g ml,1) and longest contact time (30 min). Significance and Impact of the Study:,This work highlights the need for further research into the survival of M. paratuberculosis during water treatment. [source] 31P CP/MAS NMR of polycrystalline and immobilized phosphines and catalysts with fast sample spinningMAGNETIC RESONANCE IN CHEMISTRY, Issue 6 2003S. Reinhard Abstract Cross-polarization (CP) at fast magic angle spinning (MAS) frequencies leads to a splitting of the Hartmann,Hahn (HH) matching profile into a centerband and additional bands of higher orders. The matching profiles differ with the substance categories. Therefore, signal intensity is usually lost, when e.g. the routine standard NH4H2PO4 is used for optimizing the 1H,31P HH match prior to measuring phosphines and their metal complexes in polycrystalline or immobilized form. Here, a variety of model compounds, such as Ph2PCH2CH2PPh2 and (CO)2Ni(PPh3)2, which can be used as 31P CP standards for analogous substances or materials are presented. Investigating the influences of MAS frequency, contact time, 1H pulse power and sample volume on the matching profiles of the model compounds leads to general trends. Thereby, a new strategy for measuring difficult samples with CP at high MAS rates has been developed: their optimum CP parameters are derived from the most intense maxima in the HH matching profiles of the corresponding model compounds. This new strategy is compared with variations of a conventional ramp sequence. Although the latter generally provide smaller signal half-widths, the new strategy leads to higher signal intensities. The new method was successfully applied to polycrystalline and immobilized phosphines and catalysts. Copyright © 2003 John Wiley & Sons, Ltd. [source] Evidence based guidelines and current practice for physiotherapy management of knee osteoarthritisMUSCULOSKELETAL CARE, Issue 1 2009Nicola E. Walsh MSc MCSP Abstract Objectives:,To document physiotherapy provision for patients with knee osteoarthritis (OA) in relation to the United Kingdom (UK) recently published National Institute of health and Clinical Excellence (NICE) guidelines for osteoarthritis. Design:,Questionnaire survey of chartered physiotherapists. Method:,300 postal questionnaires were distributed to Physiotherapy Departments requesting information regarding source of referrals, treatment aims, preferred methods of treatment and service delivery. Results:,Responses were received from 83 physiotherapists (28 %), predominantly working in the UK National Health Service. Approximately equal numbers of referrals came from primary and secondary care. Aims of physiotherapy management were to; encourage self-management; increase strength and range of movement; reduce pain; and improve function. To achieve these, exercise was utilised by 100% of practitioners, often supplemented with electrotherapeutic modalities (66%), manual therapy (64%) and acupuncture (60%). The majority of patients received individual treatment for a total contact time of 1,2 hours, whilst most group interventions lasted 5,6 hours. Approximately half (54%) of respondents reported using outcome measures to determine treatment efficacy. Conclusions:,Although knee OA is usually managed in primary care, the similar number of referrals from primary and secondary care may suggest a deviation from evidence-based management guidelines. The guidelines' recommendations of exercise, patient education and self-management are observed by physiotherapists, but other modalities are often used despite poor or no research evidence supporting their efficacy. Whether any of these interventions are clinically beneficial is speculative as treatment outcomes were frequently under-evaluated. Copyright © 2008 John Wiley & Sons, Ltd. [source] Pes planovalgus in RA: a descriptive and analytical study of foot function determined by gait analysisMUSCULOSKELETAL CARE, Issue 1 2003Deborah E. Turner BSc SRCh Abstract Objective: To compare gait and foot function between rheumatoid arthritis (RA) patients with painful pes planovalgus deformity and healthy age- and sex-matched adults. Methods: Gait analysis was undertaken in 23 RA patients (14 female and 9 male, mean age 52.3 years, mean disease duration 6.6 years) and 23 healthy adults (14 female and 9 male, mean age 49.5 years). Gait measurements included temporal and spatial parameters, plantar pressures and three-dimensional (3D) kinematics at the ankle joint complex (AJC). The mean differences between the groups and associated confidence intervals were calculated using the t distribution. Results: RA patients showed longer gait cycle (mean difference 0.15 sec and 0.14 sec for right and left limbs, respectively) and double-limb support times (mean difference 8.3% and 7.9% for right and left limbs, respectively), shorter stride length (mean difference ,0.31 m for right and left limbs), slower walking speed (mean difference ,0.39 m/sec) and lower cadence (mean difference ,16.6 steps/min). In comparison with the normal group, RA patients had greater AJC dorsi/plantarflexion range of motion (ROM) (mean difference 5.7 °) and inversion/eversion ROM (mean difference 2.9 °). The frontal plane position of the AJC was more everted at specific stance periods (mean difference at heel strike ,2.4 ° and at midstance ,4.0°). Furthermore, both the peak eversion (mean difference ,4.1 °) and summated eversion motion as a function of time (mean difference ,313.9 °) were greater in the RA group. The pes planovalgus foot in RA was characterized by increases in peak pressure (mean difference 34.3 kPa), pressure,time integral (mean difference 18.2 kPa.sec), peak force (mean difference 1.7 N), force,time integral (mean difference 0.7 N.sec), contact time (mean difference 9.8% roll over process) and contact area (mean group difference 3.4 cm,2) in the medial midfoot. Further changes in the load pattern in the forefoot were observed in the RA patients, namely increases in the peak pressure (mean difference 96.4 kPa), pressure,time integral (mean difference 58.4 kPa.sec), and contact area (mean difference 1.7 cm,2) in the medial forefoot region and reduction in contact area (mean difference ,3.9 cm,2), peak force (mean difference ,7.2 N) and force,time integral (mean difference ,1.6 N.sec) in the lateral forefoot. Conclusions: Painful pes planovalgus deformity in RA is associated with global changes in gait, and localized structural and functional changes in the foot which can be accurately measured using clinical gait analysis. Copyright © 2003 Whurr Publishers Ltd. [source] | |||||||||||||||||||||||||||||||||||||