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Batch Experiments (batch + experiment)
Selected AbstractsOrganic carbon and nitrogen removal in anoxic/oxic-membrane bioreactor treating high-strength wastewaterENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2009Zhimin Fu Abstract The performance of an anoxic/oxic membrane bioreactor system for the simultaneous removal of nitrogen and chemical oxygen demand (COD) was investigated. This process removed up to 87% of total nitrogen (TN) and 94% of COD, with the influent concentrations of 200 mg NH4+ -N/L and 4000 mg COD/L and a recycle ratio (R) of 200%. Biological assimilation and simultaneous nitrification and denitrification (SND) were considered on nitrogen removal process. The TN removal efficiency was above 87.5%, while the nitrogen being removed through SND was above 75.5% and nitrogen assimilated into the biomass was below 24.5%, with influent concentration below 200 mg NH4+ -N/L. Increasing the influent concentration to 400 mg NH4+ -N/L, TN removal efficiency decreased significantly to 37.5%, of which 49.5% was provided by microorganism growth. Batch experiments provided evidence for the phenomena of SND. Furthermore, the SND removal efficiency increased gradually from 26.8 to 90.0%. © 2008 American Institute of Chemical Engineers Environ Prog, 2009 [source] Effect of water composition on phosphorus concentration in runoff and water-soluble phosphate in two grassland soilsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2006M. Schärer Summary Many irrigation experiments determine phosphorus (P) losses from soil. Often, these studies cannot be compared, because the irrigation water was not characterized. We used calcium-rich tap water and deionized water to investigate the influence of water composition on P concentrations in induced runoff. We irrigated two grassland sites: one acid and one calcareous. Less P was measured in runoff from tap water irrigation than from deionized water, especially for the acid soil. Batch experiments confirmed the findings of the field experiments. Tap water decreased water-soluble phosphate and increased calcium in the solid phase. This interaction increased with decreasing soil:water ratio. Water of low ionic strength gave results comparable to rainwater. Our findings demonstrate that solution chemistry and the soil:water ratio can strongly influence the availability of P for transport. We recommend that P tests or irrigation experiments should use water resembling that of the system of interest. Irrigation experiments aiming to simulate P losses by surface runoff should be carried out with water having a composition comparable to rainwater. [source] Sorption and leaching behaviour of polar aromatic acids in agricultural soils by batch and column leaching testsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 3 2005R. Celis Summary Aromatic acids can reach the soil from direct anthropogenic activities or, indirectly, from the degradation of many aromatic compounds, such as pesticides or polycyclic aromatic hydrocarbons. Because of the anionic character of aromatic acids at the pH of most soil and sediment environments, they are expected to move rapidly through the soil profile and to pose a great risk of ground water contamination. We designed batch and column leaching tests to characterize the behaviour of three aromatic acids differing in their chemical structures, picloram (4-amino-3,5,6-trichloropicolinic acid), phthalic acid (2,2-benzenedicarboxylic acid), and salicylic acid (2-hydroxybenzoic acid), in four European soils with different physicochemical characteristics. Batch experiments revealed that the persistence of the three acids in soil:water suspensions decreased in the order: picloram , phthalic acid > salicylic acid, and their dissipation curves were relatively independent of soil type. Sorption by the soils, their clay-size fractions and model sorbents indicated much greater affinity of soil constituents for salicylic acid than for picloram or phthalic acid, most likely due to the ability of salicylic acid to form bidentate complexes with positively charged soil components. The extent of leaching of the aromatic acids in hand-packed soil columns decreased in the order: picloram (90,96%) > phthalic acid (25,90%) > salicylic acid (0,37%), which was consistent with the sorption and persistence results of the batch tests. The organic C content, the amount of small-size pores, and the initial concentration of aromatic acid in soil appeared to be important factors influencing the leaching patterns of phthalic acid and salicylic acid in the soils studied, but did not greatly influence the leaching pattern of picloram. Sorption and leaching of polar aromatic acids in soil can therefore vary considerably depending on the structural characteristics of the aromatic acid or soil type. [source] Investigation of Catalytic Chain Transfer Copolymerization of MethacrylatesMACROMOLECULAR REACTION ENGINEERING, Issue 5 2008Anatoly N. Nikitin Abstract Batch experiments were carried out to investigate the kinetics of catalytic chain transfer copolymerization of methyl methacrylate and n -butyl methacrylate. The Predici® model developed to represent the system describes the numerous experimental data measured at high concentrations of Co(II) catalyst, taking into account the chain-length dependencies of termination, propagation and catalytic chain transfer. The constants for catalytic chain transfer are determined as 2.3,×,104 for both methyl methacrylate and n -butyl methacrylate from fitting the experimental data. Two inhibition mechanisms are shown to describe the decrease of the polymerization rate in the presence of catalyst equally well, with an unknown impurity dissolved in initiator introduced to explain experimental profiles measured at high initiator concentrations. [source] Modified suspension-PVC particles as absorbents of ortho -dichlorobenzene from waterPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 2 2003M. Shach-Caplan Abstract Modified porous PVC particles are studied as absorbents of o-dichlorobenzene (DCB), from water. The modified particles were produced by an in-situ stabilizer-free polymerization/crosslinking of a monomer/crosslinker/peroxide solution absorbed within commercial porous suspension-type PVC particles. The modifying monomers used include styrene with divinyl benzene (DVB) as a crosslinking comonomer, methyl methacrylate (MMA), butyl acrylate (BA), or ethylhexyl acrylate (EHA) with ethylene glycol dimethacrylate (EGDMA) as a crosslinking comonomer. The effect of the nature of the monomers, morphology, porosity, surface area and composition of the modified PVC particles on DCB absorption was studied. Batch experiments (absorption rate and isotherms) were used to screen the PVC absorbents on the basis of absorption rate and absorption capacity. Continuous absorption column experiments were conducted to study the parameters characterizing the absorption process. Both the unmodified and modified PVC particles absorb DCB from water. The PBA and PEHA-modified PVC particles approach equilibrium capacity faster and have greater absorption capacity than neat PVC, PS-modified PVC and PMMA-modified PVC particles. The absorption characteristics are influenced by the modifying polymer's Tg. The rubbery nature of PBA and PEHA yields better absorption in spite of the significantly lower surface area and porosity obtained in the modified PVC particles. Thus, indicating that fast adsorption followed by bulk absorption of DCB is taking place. A clear influence of the crosslinking effect was not established. The continuous absorption experiments were found more efficient than the batch absorption experiments. Copyright © 2003 John Wiley & Sons, Ltd. [source] Kinetic Study of the Conversion of Different Substrates to Lactic Acid Using Lactobacillus bulgaricusBIOTECHNOLOGY PROGRESS, Issue 3 2000Concepción N. Burgos-Rubio Lactic acid fermentation includes several reactions in association with the microorganism growth. A kinetic study was performed of the conversion of multiple substrates to lactic acid using Lactobacillusbulgaricus. Batch experiments were performed to study the effect of different substrates (lactose, glucose, and galactose) on the overall bioreaction rate. During the first hours of fermentation, glucose and galactose accumulated in the medium and the rate of hydrolysis of lactose to glucose and galactose was faster than the convesion of these substrates. Once the microorganism built the necessary enzymes for the substrate conversion to lactic acid, the conversion rate was higher for glucose than for galactose. The inoculum preparation was performed in such a way that healthy young cells were obtained. By using this inoculum, shorter fermentation times with very little lag phase were observed. The consumption patterns of the different substrates converted to lactic acid were studied to determine which substrate controls the overall reaction for lactic acid production. A mathematical model (unstructured Monod type) was developed to describe microorganism growth and lactic acid production. A good fit with a simple equation was obtained. It was found experimentally that the approximate ratio of cell to substrate was 1 to 10, the growth yield coefficient (YXS) was 0.10 g cell/g substrate, the product yield (YPS) was 0.90 g lactic acid/g substrate, and the , parameter in the Luedeking-Piret equation was 9. The Monod kinetic parameters were obtained. The saturation constant (KS) was 3.36 g/L, and the specific growth rate (,m ) was 1.14 l/h. [source] Environmental Properties of Minerals and Contaminants Purified by the Mineralogical MethodACTA GEOLOGICA SINICA (ENGLISH EDITION), Issue 1 2004LU Anhuai Abstract The investigation of the environmental properties of minerals, i.e., environmental mineralogy, is a branch of science dealing with interactions between natural minerals and spheres of the Earth surface as well as a reflection of global change, prevention of ecological destruction, participation in biomineralogy, and remediation of environmental pollution. Pollutant treatment by natural minerals is based on the natural law and reflects natural self-purification functions in the inorganic world, similar to that of the organic world , a biological treatment. A series of case studies related to natural self-purification, which were mostly completed by our group, are discussed in this paper. In natural cryptomelane there is a larger pseudotetragonal tunnel than that formed by [MnO6] octahedral double chains, with an aperture of 0.462,0.466 nm2, filled with K cations. Cryptomelane might be a real naturally-occurring mineral of the active octahedral molecular sieve (OMS-2). CrVI -bearing wastewater can be treated by natural pyrrhotite, which is used as a reductant to reduce CrVI and as a precipitant to precipitate CrIII simultaneously. Batch experiments were conducted using the CTMAB-Montmorillonite as an adsorbent for aromatic contaminants (phenol, aniline, benzene, toluene and xylenes), which are detected frequently in the leaching water from municipal waste deposits around China. The CTMAB modification has proved very effective to enhance the adsorption capacity of the sorbent. Expansion of vermiculite develops loose interior structures, such as pores or cracks, inside briquettes, and thus brings enough oxygen for combustion and the sulfation reaction. Effective combustion of the original carbon reduces the amount of dust in the fly ash. [source] Enhancement of the NAD(P)(H) Pool in Saccharomyces cerevisiaeENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 4 2008A. Knepper Abstract Asymmetric biosyntheses allow for an efficient production of chiral building blocks. The application of whole cells as biocatalysts for asymmetric syntheses is advantageous because they already contain the essential coenzymes NAD(H) or NADP(H), which additionally can be regenerated in the cells. Unfortunately, reduced catalytic activity compared to the oxidoreductase activity is observed in many cases during whole-cell biotransformation. This may be caused by low intracellular coenzyme pool sizes and/or a decline in intracellular coenzyme concentrations. To enhance the intracellular coenzyme pool sizes, the effects of the precursor metabolites adenine and nicotinic acid on the intracellular accumulation of NAD(H) and NADP(H) were studied in Saccharomyces cerevisiae. Based on the results of simple batch experiments with different precursor additions, fed-batch processes for the production of yeast cells with enhanced NAD(H) or enhanced NADP(H) pool sizes were developed. Supplementation of the feed medium with 95,mM adenine and 9.5,mM nicotinic acid resulted in an increase of the intracellular NAD(H) concentration by a factor of 10 at the end of the fed-batch process compared to the reference process. The final NAD(H) concentration remains unchanged if the feed medium was solely supplemented with 95,mM adenine, but intracellular NADP(H) was increased by a factor of 4. The effects of NADP(H) pool sizes on the asymmetric reduction of ethyl-4-chloro acetoacetate (CAAE) to the corresponding (S)-4-chloro-3-hydroxybutanoate (S-CHBE) was evaluated with S.,cerevisiae,FasB,His6 as an example. An intracellular threshold concentration above 0.07,mM NADP(H) was sufficient to increase the biocatalytic S-CHBE productivity by 25,% compared to lower intracellular NADP(H) concentrations. [source] Electroenzymatic Synthesis of Chiral SulfoxidesENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 2 2006C. Kohlmann Abstract Chloroperoxidase (CPO) from Caldariomyces fumago (E.C.,1.11.1.10) is able to enantioselectively oxidize various sulfides to the corresponding (R)-enantiomer of the sulfoxides. For these oxidations the enzyme requires an oxidant. Most commonly, tert -butyl hydroperoxide (TBHP) and hydrogen peroxide are used. As it is known that these oxidants inactivate the enzyme, the enzymatic reaction was combined with the electrochemical in situ generation of hydrogen peroxide. As substrates for this combination of an enzymatic and an electrochemical reaction methyl p-tolyl sulfide, 1-methoxy-4-(methylthio)benzene and N-MOC- L -methionine methyl ester were used to carry out batch experiments. [source] Bioavailability and biodegradation of nonylphenol in sediment determined with chemical and bioanalysis,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2008Jasperien de Weert Abstract The surfactant nonylphenol (NP) is an endocrine-disrupting compound that is widely spread throughout the environment. Although environmental risk assessments are based on total NP concentrations, only the bioavailable fraction posses an environmental risk. The present study describes the bioavailability and biodegradability of NP over time in contaminated river sediment of a tributary of the Ebro River in Spain. The bioavailable fraction was collected with Tenax TA® beads, and biodegradation was determined in aerobic batch experiments. The presence of NP was analyzed chemically using gas chromatography-mass spectrometry and indirectly as estrogenic potency using an in vitro reporter gene assay (ER, - luc assay). Of the total extractable NP in the sediment, 95% ± 1.5% (mean ± standard error) desorbed quickly into the water phase. By aerobic biodegradation, the total extractable NP concentration and the estrogenic activity were reduced by 97% ± 0.5% and 94% ± 2%, respectively. The easily biodegradable fraction equals the potential bioavailable fraction. Only 43 to 86% of the estrogenic activity in the total extractable fraction, as detected in the ER, - luc assay, could be explained by the present NP concentration. This indicates that other estrogenic compounds were present and that their bioavailability and aerobic degradation were similar to that of NP. Therefore, we propose to use NP as an indicator compound to monitor estrogenicity of this Ebro River sediment. To what extent this conclusion holds for other river sediments depends on the composition of the contaminants and/or the nature of these sediments and requires further testing. [source] Association of europium(III), americium(III), and curium(III) with cellulose, chitin, and chitosanENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 8 2006Takuo Ozaki Abstract The association of trivalent f-elements,Eu(III), Am(III), and Cm(III),with cellulose, chitin, and chitosan was determined by batch experiments and time-resolved, laser-induced fluorescence spectroscopy (TRLFS). The properties of these biopolymers as an adsorbent were characterized based on speciation calculation of Eu(III). The adsorption study showed that an increase of the ionic strength by NaCl did not affect the adsorption kinetics of Eu(III), Am(III), and Cm(III) for all the biopolymers, but the addition of Na2CO3 significantly delayed the kinetics because of their trivalent f-element complexation with carbonate ions. It also was suggested from the speciation calculation study that all the biopolymers were degraded under alkaline conditions, leading to their masking of the adsorption of Eu(III), Am(III), and Cm(III) on the nondegraded biopolymers. The masking effect was higher for cellulose than for chitin and chitosan, indicating that of the three, cellulose was degraded most significantly in alkaline solutions. Desorption experiments suggested that some portion of the adsorbed Eu(III) penetrated deep into the matrix, being isolated in a cavity-like site. The TRLFS study showed that the coordination environment of Eu(III) is stabilized mainly by the inner spherical coordination in chitin and by the outer spherical coordination in chitosan, with less association in cellulose in comparison to chitin and chitosan. These results suggest that the association of these biopolymers with Eu(III), Am(III), and Cm(III) is governed not only by the affinity of the functional groups alone but also by other factors, such as the macromolecular steric effect. The association of degraded materials of the biopolymers also should be taken into consideration for an accurate prediction of the influence of biopolymers on the migration behavior of trivalent f-elements. [source] Fate and effects of triclosan in activated sludgeENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2002Thomas W. Federle Abstract Triclosan (TCS; 5-chloro-2-[2,4-dichloro-phenoxy]-phenol) is a widely used antimicrobial agent. To understand its fate during sewage treatment, the biodegradation and removal of TCS were determined in activated sludge. In addition, the effects of TCS on treatment processes were assessed. Fate was determined by examining the biodegradation and removal of TCS radiolabeled with 14C in the 2,4-dichlorphenoxy ring in laboratory batch mineralization experiments and bench-top continuous activated-sludge (CAS) systems. In batch experiments with unacclimated sludge, TCS was mineralized to 14CO2, but the total yield varied as a function of test concentration. Systems that were redosed with TCS exhibited more extensive and faster mineralization, indicating that adaptation was a critical factor determining the rate and extent of biodegradation. In a CAS study in which the influent level of TCS was incrementally increased from 40 ,g/L to 2,000 ,g/L, removal of the parent compound exceeded 98.5% and removal of total radioactivity (parent and metabolites) exceeded 85%. Between 1.5 and 4.5% of TCS in the influent was sorbed to the wasted solids, whereas >94% underwent primary biodegradation and 81 to 92% was mineralized to CO2 or incorporated in biomass. Increasing levels of TCS in the influent had no major adverse effects on any wastewater treatment process, including chemical oxygen demand, biological oxygen demand, and ammonia removal. In a subsequent experiment, a CAS system, acclimated to TCS at 35 ,g/L, received two separate 4-h shock loads of 750 ,g/L TCS. Neither removal of TCS nor treatment processes exhibited major adverse effects. An additional CAS study was conducted to examine the removal of a low level (10 ,g/L) of TCS. Removal of parent equaled 94.7%, and biodegradation remained the dominant removal mechanism. A subsequent series of CAS experiments examined removal at four influent concentrations (7.5, 11, 20, and 50 ,g/L) of TCS and demonstrated that removal of parent ranged from 98.2 to 99.3% and was independent of concentration. Although TCS removal across all experiments appeared unrelated to influent concentration, removal was significantly correlated (r2 = 0.87) with chemical oxygen demand removal, indicating that TCS removal was related to overall treatment efficiency of specific CAS units. In conclusion, the experiments show that TCS is extensively biodegraded and removed in activated-sludge systems and is unlikely to upset sewage treatment processes at levels expected in household and manufacturing wastewaters. [source] Effect of mass-transfer limitations on bioavailability of sorbed naphthalene in synthetic model soil matricesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2000Hendricus Mulder Abstract External and internal mass-transfer resistances influencing the bioavailability of sorbed naphthalene in a synthetic model matrix for soil aggregates were investigated in batch experiments in mixed reactors. Amberlite® adsorption resins (XAD4 and XAD7) were used as the synthetic model for soil aggregates. The effect of hydrodynamic conditions in the slurry phase on the diffusive transport across a stagnant film surrounding the model particles was studied. In addition, a mechanistic model was developed based on mass balances, diffusion equations, a nonlinear sorption isotherm, and microbial degradation kinetics. Experimental results could be explained well with this model. In the absence of external transfer limitations, intraparticle effective diffusion coefficients of (3.55 ± 0.10) × 10,9 m2/s and (5.29 ± 0.86) × 10,10 m2/s were determined for naphthalene in Amberlite XAD4 and XAD7, respectively. [source] Interactions of ferricyanide with humic soils and charred strawEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2008T. Rennert Summary The iron-cyanide complexes ferricyanide, [FeIII(CN)6]3,, and ferrocyanide, [FeII(CN)6]4,, are anthropogenic contaminants in soil. We studied the interactions of ferricyanide with humic soils and charred straw (maize and rye, both charred at 300, 400 and 500°C) by batch experiments and Fourier transform infrared (FTIR) spectroscopy. All soil samples sorbed ferricyanide (up to 8.4 g kg,1). Precipitation of a manganese ferrocyanide after reduction of ferricyanide in the moderately acidic to neutral soils was deduced from both FTIR spectroscopy (CN absorption bands at 2069,2065 cm,1) and geochemical modelling. Ferricyanide was also adsorbed onto the charred straw. The amounts of iron-cyanide complexes adsorbed increased with increasing charring temperature, with a maximum of 1.71 g kg,1. An absorption band at 2083 cm,1 indicated weakly adsorbed intermediates of the reduction of ferricyanide to ferrocyanide. This band disappeared in the samples charred at higher temperature, whereas a band at 2026 cm,1 was present in all spectra and became intensified in the high-temperature straw. We attribute this band to ferrocyanide forming inner-sphere complexes, presumably with quinone species of the organic matter. The band at 2026 cm,1 was also present in the spectra of the soils, indicating that soil organic matter also adsorbs ferrocyanide. However, in humic soils the main processes of ferricyanide interaction include reduction to ferrocyanide and precipitation as manganese ferrocyanide. Quantitatively, adsorption on highly aromatic substances plays only a less important role as compared with precipitation. [source] A model describing the interactions between anaerobic microbiology and geochemistry in a soil amended with glucose and nitrateEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 1 2004F. Dassonville Summary Under anaerobic conditions, microbes closely interact with geochemical reactions and can have an impact on the soil, the deep vadose zone, the underlying aquifer and the atmosphere. We have designed a model combining anaerobic microbial activities with geochemical reactions in the soil, and assessed it in batch experiments. The model describes the dynamics of six functional microbial communities, their decomposition after death, and the catabolism of carbohydrates through denitrification, dissimilatory NH4+ production, Fe(III) reduction, fermentation, acetogenesis, and SO42, reduction. It was combined with a model that thermodynamically describes acid,base, reduction,oxidation and complexation reactions in solution, and kinetic precipitation and dissolution. Batch incubations were done on a Calcic Cambisol, either without amendment, or after supplying (i) glucose or (ii) glucose and NO3,. Gases, mineral cations and anions, glucose, fatty acids and alcohols were measured during incubation. Net production of CO2 was similar for both glucose treatments, about 40 times larger than in the control. For the glucose treatments, the main microbial activities were fermentation, acetogenic transformation of ethanol, and oxidation of H2. When the soil was enriched with NO3,, no H2 was produced, and microbial activities were rapidly inhibited by NO2,. The model shows these trends as well as geochemical characteristics including pH and reduction,oxidation potential. [source] Utilization of semi-natural grassland through integrated generation of solid fuel and biogas from biomass.GRASS & FORAGE SCIENCE, Issue 4 2009Abstract A procedure (Integrated Generation of Solid Fuel and Biogas from Biomass, IFBB) was developed which uses a screw press to separate the readily digestible constituents of mature grassland biomass into a press fluid for conversion into biogas and a fibrous press cake for processing into a solid fuel. Effects of mechanical dehydration and prior hydrothermal conditioning at different temperatures (5, 60 and 80°C) on concentrations of organic compounds in the press fluid and on methane production in batch experiments were evaluated for five semi-natural grasslands typical of mountain areas of Germany. Results show that the crude protein concentration of the press fluids was higher and crude fibre concentration was lower than that of the parent material (herbage conserved as silage). Digestion tests in batch fermenters showed that the methane yield of the press fluids was double [397,426 normal litre (NL) kg,1 volatile solids (VS) after 13 d] that of the whole-crop grassland silage (218 NL kg,1 VS after 27 d) but no consistent effect of higher temperature during conditioning was observed. Within 13 d of fermentation the decomposition of the organic matter (OM) that occurred in the press fluids was 0·90, whereas after 27 d of fermentation more than 0·40 of the OM remained undigested in the whole-crop silage, pointing at a marked reduction in retention time for anaerobic digestion of press fluids in continuous systems. Press fluids produced 0·90 of the maximum methane yield after 4 to 7 d compared with 19 days for the whole-crop silage. [source] Polyurethane- and Polystyrene-Supported 2,2,6,6-Tetramethyl- piperidine-1-oxyl (TEMPO); Facile Preparation, Catalytic Oxidation and Application in a Membrane ReactorADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2008Muhammad Afzal Subhani Abstract In this contribution, the facile synthesis of two new polymer-supported 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) catalysts and their application in the catalytic oxidation of alcohols to carbonyl compounds are described. For attachment of the TEMPO group to the polymer an isocyanate functionalized polymer is chosen. This new approach facilitates the synthesis in comparison with previously existing methods which generally require deprotonation of TEMPO prior to reaction with the polymer. Following this approach, polyurethane (PU)- and polystyrene (PS)-based TEMPO catalysts are prepared in a one-step reaction from commercially available compounds. Both polymer-supported catalysts showed promising yields for a variety of substrates using inorganic and/or organic co-oxidants in biphasic and/or monophasic systems. The recyclability of the corresponding catalysts was studied in repetitive batch experiments using filtration or distillation depending on the support type. Furthermore, application of the homogeneous polyurethane-supported TEMPO for the selective oxidation of benzyl alcohol in a continously operated membrane reactor is demonstrated. [source] Sorption of copper by a highly mineralized peat in batch and packed-bed systemsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2010Marta Izquierdo Abstract BACKGROUND: The performance of peat for copper sorption was investigated in batch and fixed-bed experiments. The effect of pH was evaluated in batch experiments and the experimental data were fitted to an equilibrium model including pH dependence. Hydrodynamic axial dispersion was estimated by tracing experiments using LiCl as a tracer. Six fixed-bed experiments were carried out at copper concentrations between 1 and 60 mg dm,3 and the adsorption isotherm in dynamic mode was obtained. A mass transport model including convection,dispersion and sorption processes was applied for breakthrough curve modelling. RESULTS: Maximum uptake capacities in batch mode were 22.0, 36.4, and 43.7 mg g,1 for pH values of 4.0, 5.0, and 6.0, respectively. Uptake capacities in continuous flow systems varied from 36.5 to 43.4 mg g,1 for copper concentrations between 1 and 60 mg dm,3. Dynamic and batch isotherms showed different shapes but a similar maximum uptake capacity. Sorbent regeneration was successfully performed with HCl. A potential relationship between dispersion coefficient and velocity was obtained with dispersion coefficients between 5.00 × 10,8 and 2.95 × 10,6 m2 s,1 for water velocities ranging between 0.56 × 10,4 and 5.03 × 10,4 m s,1. The mass transport model predicted both the breakpoints and the shape of the breakthrough curves. CONCLUSIONS: High retention capacities indicate that peat can be used as an effective sorbent for the treatment of wastewater containing copper ions. Copyright © 2009 Society of Chemical Industry [source] Biodegradation kinetics of benzene, methyl tert -butyl ether, and toluene as a substrate under various substrate concentrationsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2007Chi-Wen Lin Abstract Owing to the complexity of conventional methods and shortcomings in determining kinetic parameters, a convenient approach using the nonlinear regression analysis of Monod or Haldane type nonlinear equations is presented. This method has been proven to provide accurate estimates of kinetic parameters. The major work in this study consisted of the testing of aromatic compound-degrading cultures in batch experiments for the biodegradation of benzene, methyl tert -butyl ether (MTBE), and toluene. Additionally, batch growth data of three pure cultures (i.e., Pseudomonas aeruginosa YAMT421, Ralstonia sp. YABE411 and Pseudomonas sp. YATO411) isolated from an industrial petrochemical wastewater treatment plant under aerobic conditions were assessed with the nonlinear regression technique and with a trial-and-error procedure to determine the kinetic parameters. The growth rates of MTBE-, benzene-, and toluene-degrading cultures on MTBE, benzene, and toluene were significant. Monod's model was a good fit for MTBE, benzene and toluene at low substrate concentrations. In contrast, Haldane's equation fitted well in substrate inhibition concentration. Monod and Haldane's expressions were found to describe the results of these experiments well, with fitting values higher than 98%. The kinetic parameters, including a maximum specific growth rate (µm), a half-saturation constant (Ks), and an inhibition constant (Ki), were given. Copyright © 2007 Society of Chemical Industry [source] Intermediate accumulation and efficiency of anaerobic digestion treatment of surfactant (alcohol sulfate)-rich wastewater at increasing surfactant/biomass ratiosJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2002Heiko Feitkenhauer Abstract Textile (eg cotton) finishing industry wastewater is characterised by high concentrations of surfactants (up to 2,g,dm,3) and of readily biodegradable biopolymers (COD 5,15,g,dm,3). The anionic surfactant decyl sulfate (DS) was chosen as model surfactant and soluble starch (size) as model compound for the readily biodegradable fraction of the wastewater. Twenty-two batch experiments with increasing DS/biomass ratio (and starch/biomass ratio) were started simultaneously. Biomass concentrations ranged from 50 to 15,000,mg,dm,3. Minor inhibition effects were found for the surfactant degradation itself at all DS/biomass ratios (maximum biodegradation rate 7.7,mgDS gbiomass,1h,1). The starch hydrolysis started without a lag-phase at DS/biomass ratios of up to 0.15,gDS gbiomass,1. The lag-phase was prolonged to about 100,h at a very high DS/biomass ratio (3,gDS gbiomass,1). The relative importance of the accumulated intermediates was dependent on the DS/biomass ratio. Above 0.3,gDS gbiomass,1 10% of the substrate organic carbon accumulated as ethanol, but no ethanol accumulation was observed at low DS/biomass ratios. Moderate DS/biomass ratios caused a considerable delay of the methanogenesis; high DS/biomass ratios prevented the methanogenesis almost completely. © 2002 Society of Chemical Industry [source] Removal of toxic metal ions from aqueous systems by biosorptive flotationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2002Anastasios I Zouboulis Abstract Biosorptive flotation was used as a combined operation for the simultaneous abstraction of nickel, copper and zinc ions from aqueous streams. Laboratory-scale batch experiments, as well as pilot-scale continuous experiments, have been conducted. Grape stalks, a by-product of the winery industry, were used as sorbent material. The experimental procedure consisted of two consecutive stages: (i) biosorption, and (ii) flotation. The possibility of reusing biomass, after appropriate elution, was also examined. The main parameters examined were biomass concentration, particle size of sorbent, surfactant concentration, pH and flocculation. Flotation removals, following laboratory-scale experiments, were found to be in the order of 100, 85 and 70% for copper, zinc and nickel, respectively. In pilot-scale experiments, biomass sorption capacities were determined as 25 for copper, 81 for zinc and 7,µmol,dm,3 for nickel. The order of biomass affinity regarding the studied metals was Cu,>,Zn,>,Ni. Short retention time and high effectiveness suggest that biosorptive flotation is a promising treatment process for the removal of toxic metals from contaminated aqueous solutions. © 2002 Society of Chemical Industry [source] Separation of fullerenes C60 and C70 using a crystallization-based processAICHE JOURNAL, Issue 7 2010Kui S. Kwok Abstract A crystallization-based process that separates pure fullerenes C60 and C70 from their mixture using o-xylene as the solvent has been developed. Isothermal solid,liquid equilibrium phase diagrams of the C60 -C70 -o-xylene ternary system for a number of temperatures were first determined at 1 atm. Taking advantage of the shift in solvent-free composition of the C60 -C70 double saturation point with temperature and based on the solid solution-forming phase behavior between C60 and C70, the flowsheet of a general crystallization process was then synthesized. It involved the fractionation of a C60 -C70 fullerene mixture into C60 -rich and C70 -rich solid solutions using temperature-swing crystallization, followed by purification of the solid solutions with multistage crystallization into pure C60 and C70 solids. To demonstrate process feasibility, bench-scale batch experiments were performed using a commercially available fullerene mixture that was pretreated by adsorption to remove higher fullerenes. C60 and C70 solids of purity higher than 99 wt % were obtained. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Kinetic and dynamic study of liquid,liquid extraction of copper in a HFMC: Experimentation, modeling, and simulationAICHE JOURNAL, Issue 6 2010M. Younas Abstract In this work, we present the dispersion-free liquid,liquid extraction of copper from aqueous streams in a hollow fiber membrane contactor (HFMC). Copper has been transferred from aqueous solutions to heptane using LIX 84-I (2-hydroxy-5-nonylacetephenone oxime) as extracting agent. In a first step, batch experiments have been performed to identify the extraction kinetics and to measure the partition coefficient of copper aqueous-organic phase system. Then, the continuous recycled-base extraction process has been performed in a HFMC Liqui-Cel® module. The module has been modeled from resistance in series concept to gain the exit concentrations, which are used to develop a dynamic model to calculate the exit concentration of copper from the output of storage tanks. The model has been validated with experimental data at various operating conditions. The integrated process model algorithm was scripted in MATLAB® 7.4 R (a). Simulations have been made for a range of different operating parameters to determine the optimum criterion conditions. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Hydrogen response in liquid propylene polymerization: Towards a generalized modelAICHE JOURNAL, Issue 5 2006M. Al-haj Ali Abstract Liquid propylene batch experiments in the absence of a gas phase have been carried out using a highly-active MgCl2/TiCl4/phthalate/silane/AlR3 catalyst at varying temperatures (60-80°C) and molar hydrogen-monomer ratios of 0-10 mmol/mol. With increasing hydrogen concentration the polymerization rate increases rapidly, reaching a constant value at concentrations above 1.4 mmol/mol; pseudo-first-order catalyst deactivation constant increases; molecular weight decreases; polydispersity decreases slightly; but average molecular weight and polydispersity increase with increasing temperature. Polymerization rate, deactivation constant, and average molecular weight can be modeled based on a consistent dormant site mechanism assuming an (averaged) quasi-single-site model. © 2006 American Institute of Chemical Engineers AIChE J,2006 [source] Functionalized HMS mesoporous silica as solid phase extractant for Pb(II) prior to its determination by flame atomic absorption spectrometryJOURNAL OF SEPARATION SCIENCE, JSS, Issue 10 2007Damián Pérez-Quintanilla Abstract In this work, a mesoporous silica has been chemically modified with 5-mercapto-1-methyl-1-H-tetrazol using the homogeneous route (MTTZ-HMS). This synthetic route involved the reaction of 5-mercapto-1-methyl-1-H-tetrazol with 3-chloropropyltriethoxysilane, prior to immobilization on the support. The resulting material has been characterized and employed as solid phase extractant for Pb(II). The effect of several variables (stirring time, pH, temperature, metal concentration, presence of other metals) has been studied using batch and column techniques. In batch experiments, 15 min stirring time, 55°C and pH 8 were the optimal conditions for Pb(II) adsorption. In column experiments, sorption was quantitative for 1000 mL of 2.41×10,4 mM of Pb(II) solution and adsorbed ions were eluted out by 5 mL of 1 M HCl (preconcentration factor of 200). Spiked tap water was used for the preconcentration and determination of Pb(II) by flame atomic absorption spectrometry, and a 100% recovery was obtained. The LOD and LOQ values of the proposed method were found to be 3.52×10,3 and 4.20×10,3 mM, respectively. The RSD for three preconcentration experiments was found to be ,2%. The linear working range for measurements was between 2×10,3 and 0.14 mM (y = 0.0136x + 0.0007, R2 = 0.9999). [source] Thermal Initiation of MMA in High Temperature Radical PolymerizationsMACROMOLECULAR MATERIALS & ENGINEERING, Issue 4 2005Philip Nising Abstract Summary: Several researches have dealt with the thermal initiation of methyl methacrylate (MMA) in the past. Some of them already discussed the presence of peroxide containing species that are formed from dissolved oxygen and the monomer itself as main reason for this initiation. However, a more detailed investigation as well as a kinetic description of this phenomenon is still due in literature. In this paper, the formation and decomposition of methyl methacrylate peroxides are described. MMA that has been in contact with air forms macromolecular peroxides at temperatures below 100,°C from physically dissolved oxygen. These peroxides have molecular weights of approximately 3,000,5,000 g,·,mol,1, depending on the temperature during formation. Above this temperature, these peroxides decompose quickly and initiate the radical polymerization. Depending on the reaction conditions, monomer conversions from 15 to 30% are obtained. In combination with additional initiators, the MMA peroxides provoke an acceleration of the reaction rate and can also lead to bimodal molecular weight distributions. An analytical method based on UV-spectrophotometry was developed for the quantification of the peroxide content in the monomer. The kinetic rate constants for the formation were determined in batch experiments with purified, air-saturated monomer to be kf,0,=,6.28,·,107 l2,·,mol,2,·,s and EA,=,7.75,·,104 J,·,mol,1. The decomposition rate constants were determined from batch dead-end polymerizations and found to be kd,0,=,4.73,·,107 l,·,mol,1,·,s,1 and EA,=,8.56,·,104 J,·,mol,1. [source] Modelling approaches to compare sorption and degradation of metsulfuron-methyl in laboratory micro-lysimeter and batch experimentsPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 12 2003Maik Heistermann Abstract Results of laboratory batch studies often differ from those of outdoor lysimeter or field plot experiments,with respect to degradation as well as sorption. Laboratory micro-lysimeters are a useful device for closing the gap between laboratory and field by both including relevant transport processes in undisturbed soil columns and allowing controlled boundary conditions. In this study, sorption and degradation of the herbicide metsulfuron-methyl in a loamy silt soil were investigated by applying inverse modelling techniques to data sets from different experimental approaches under laboratory conditions at a temperature of 10 °C: first, batch-degradation studies and, second, column experiments with undisturbed soil cores (28 cm length × 21 cm diameter). The column experiments included leachate and soil profile analysis at two different run times. A sequential extraction method was applied in both study parts in order to determine different binding states of the test item within the soil. Data were modelled using ModelMaker and Hydrus-1D/2D. Metsulfuron-methyl half-life in the batch-experiments (t1/2 = 66 days) was shown to be about four times higher than in the micro-lysimeter studies (t1/2 about 17 days). Kinetic sorption was found to be a significant process both in batch and column experiments. Applying the one-rate-two-site kinetic sorption model to the sequential extraction data, it was possible to associate the stronger bonded fraction of metsulfuron-methyl with its kinetically sorbed fraction in the model. Although the columns exhibited strong significance of multi-domain flow (soil heterogeneity), the comparison between bromide and metsulfuron-methyl leaching and profile data showed clear evidence for kinetic sorption effects. The use of soil profile data had significant impact on parameter estimates concerning sorption and degradation. The simulated leaching of metsulfuron-methyl as it resulted from parameter estimation was shown to decrease when soil profile data were considered in the parameter estimation procedure. Moreover, it was shown that the significance of kinetic sorption can only be demonstrated by the additional use of soil profile data in parameter estimation. Thus, the exclusive use of efflux data from leaching experiments at any scale can lead to fundamental misunderstandings of the underlying processes. Copyright © 2003 Society of Chemical Industry [source] Catalytic role of manganese in autoclave oxidation of germanium-rich sphalerite concentratesTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2009Liang Duoqiang Abstract An attempt was made to investigate the catalytic role of manganese in enhancing the reaction rate with respect to autoclave oxidation of germanium-rich sphalerite concentrates. A series of batch experiments was performed in different conditions to investigate the variables such as temperature and oxygen pressure. Experimental results obtained show that as a catalyst, aqueous divalent manganese can accelerate the leaching of sphalerite concentrates significantly. On a tenté d'étudier le rôle catalytique du manganèse pour améliorer la vitesse de réaction de l'oxydation en autoclave de concentrés de sphalérite riche en germanium. Une série d'expériences discontinues ont été menées dans différentes conditions afin d'étudier les variables telles que la température et la pression d'oxygène. Les résultats expérimentaux obtenus montrent qu'en tant que catalyseur, le manganèse divalent aqueux peut significativement accélérer la lixiviation des concentrés de sphalérite. [source] Degradation and effect of hydrogen peroxide in small-scale recirculation aquaculture system biofiltersAQUACULTURE RESEARCH, Issue 8 2010Martin Sune Møller Abstract From an environmental point of view, hydrogen peroxide (HP) has beneficial attributes compared with other disinfectants in terms of its ready degradation and neutral by-products. The rapid degradation of HP can, however, cause difficulties with regard to safe and efficient water treatment when applied in different systems. In this study, we investigated the degradation kinetics of HP in biofilters from water recirculating aquaculture systems (RAS). The potential effect of HP on the nitrification process in the biofilters was also examined. Biofilter elements from two different pilot-scale RAS were exposed to various HP treatments in batch experiments, and the HP concentration was found to follow an exponential decay. The biofilter ammonia and nitrite oxidation processes showed quick recuperation after exposure to a single dose of HP up to 30 mg L,1. An average HP concentration of 10,13 mg L,1 maintained over 3 h had a moderate inhibitory effect on the biofilter elements from one of the RAS with relatively high organic loading, while the nitrification was severely inhibited in the pilot-scale biofilters from the other RAS with a relatively low organic loading. A pilot-scale RAS, equipped with two biofilter units, both a moving-bed (Biomedia) and a fixed-bed (BIO-BLOK®) biofilter, was subjected to an average HP concentration of ,12 mg L,1 for 3 h. The ammonium- and nitrite-degrading efficiencies of both the Biomedia and the BIO-BLOK® filters were drastically reduced. The filters had not reverted to pre-HP exposure efficiency after 24 h, suggesting a possible long-term impact on the biofilters. [source] Selective Removal of Circulating Immune Complexes from Patient PlasmaARTIFICIAL ORGANS, Issue 2 2002Siegfried Kunkel Abstract: The principle of a patient-specific immunoadsorber (PsIA) is demonstrated. Studies with model systems (HSA/anti-HSA) on immobilization, stability, and leakage form the basis for the presented fast-performance liquid chromatography (FPLC) and batch experiments, which were conducted using two different protein A adsorbers and autologous and heterologous PsIA systems. Experiments to determine the binding capacity of protein A adsorbers and PsIAs are described. In all experiments, the adsorption of plasma IgG, total protein, and C1q and C3d circulating immune complexes were measured. Plasma of patients with autoimmune diseases (rheumatoid arthritis, systemic lupus erythematosus) was investigated. Analysis was performed in both the initial plasma and the flow-through or supernatant. Results of the investigations using FPLC and batch experiments were compared. Autologous PsIA systems are suitable for the selective removal of elevated levels of circulating immune complexes in the plasma. [source] | ||||||||||||||||||||||