Purification of Ellagic Acid by UF Membranes

Ellagic acid (2, 3, 7, 8‐tetrahydroxy(1)benzopyrano(5, 4, 3‐cde)(1)benzopyran‐5, 10‐dione) was selected as a model pollutant which is present in the tannic fraction of cork processing wastewater. The ultrafiltration of aqueous ellagic acid solutions through three membranes was studied in tangential UF laboratory equipment. Two of the membranes were polyethersulfone (Biomax10K and Biomax5K, with MWCO of 10000 and 5000 Da, respectively), and the third made of regenerated cellulose (Ultracel5K, with MWCO of 5000 Da). The water hydraulic permeability was evaluated for each membrane. The evolution of the permeate flow rate with processing time was followed, and the influence of the main operating variables (feed flow rate, trans‐membrane pressure and nature of the membranes) on the permeate flux was also established. According to the hypothesis of the film theory, the intrinsic and apparent rejection coefficients, as well as the mass transfer coefficients, were also determined, and the values obtained were discussed as a function of the operating conditions used.     

Formation of Ketoacids in Ozonated Drinking Water

Three ketoacids; glyoxylic acid, pyruvic acid and ketomalonic acid, were identified in ozonated drinking waters and fulvic acid solutions using gas chromatography-mass spectrometry. It was found that the concentrations of ketoacids were much higher than those of aldehydes in ozonated waters. The significance of ketoacids in finished drinking waters is discussed.     

Study of the Catalytic Ozonation of Humic Substances in Water and Their Ozonation Byproducts

It is shown that using transition metals, especially Mn(II) and Ag(I), during ozonation of humic substances in water allows important reductions in the content of organic matter. Characterization of the organic compounds resulting from ozonation was made by concentrating the sample through liquid-liquid extraction or derivation with PFBOA.HCl, along with the GC/MS and GC/ECD techniques. In total, 110 different organic compounds were identified using GC/MS; mainly carboxylic acids, aromatics, hydrocarbons, aldehydes, ketones, and furan-carboxylic acids. The percentages of elimination or formation levels reached during ozonation are discussed.     

GC/MS characterization of effluents front the ozone bleaching of eucalypt kraft pulps

Concerns regarding the possible environmental effects of organochlorine by‐products from bleaching of pulp with chlorine‐based compounds have led to the pulp and paper industry developing new bleaching sequences. Ozone, oxygen and hydrogen peroxide are the main reagents in these Totally Chlorine Free (TCF) bleaching processes.

In this study, eucalypt kraft pulps from a variety of Australian wood sources were subjected to bleaching sequences comprising oxygen, ozone and hydrogen peroxide/alkali extraction stages. The aqueous liquid effluents from each stage were analyzed by GC/MS for aldehydes, ketones, alcohols, carboxylic acids and other by‐products. Pentafluorobenzyl oxime derivatives of the aldehydes and ketones were analyzed by electron impact GC/MS. The major carbonyl compounds detected were formaldehyde, glyoxal, dimethylglyoxal and acetone. An homologous series of n‐aldehydes corresponding to cleavage of ω‐3, 6, 9 and 12 unsaturated fatty acids also was detected. Aromatic aldehydes were identified in the oxygen stage and high consistency ozone stages, but not in any medium consistency ozone or post‐ozone bleach stages. In all stages a series of saturated alkyl carboxylic acids from formic to octacosanoic acid was detected. Formic and acetic acids were present in the highest yield. Only trace quantities of unsaturated fatty acids were detected. Details of these and other compounds detected are discussed.     

反应气相色谱法测定饮用水中的氯乙酸

采用固相提取法从饮用水中分离出氯乙酸进行酯化，并将其转化为三氟乙酸酯，通过实验确定了最佳酯化条件，并用电子俘获检测器进行气相色谱分离和测定。     

Improved Anaerobic Process Efficiency Using Mesophilic and Thermophilic Elutriated Phased Treatment

An innovative anaerobic digestion elutriated phased treatment (ADEPT) has been evaluated at mesophilic (M-ADEPT) (35°C) and thermophilic (T-ADEPT) (55°C) temperatures in which the organic loading rate (OLR) was increased until reactor failure (pH<5.5). Single-stage continuously stirred tank reactors (CSTRs) at both temperatures were also operated as controls (M-CSTR for 35°C and T-CSTR for 55°C). The T-CSTR failed at an OLR of 7.4 g volatile solid (VS)/L?day and the M-CSTR at an OLR of 10 g VS/L?day while the M-ADEPT continued until an OLR of 18 g VS/L?day and the T-ADEPT reached an OLR of 24 g VS/L?day before system failure. The T-CSTR produced the poorest effluent quality as manifested by high propionate concentrations (1,500–2,500 mg/L) while both M-ADEPT and T-ADEPT produced much better quality of effluent with propionate concentrations below 100 mg/L. Thus it appears that the T-ADEPT design may solve effluent quality problems associated with normally high propionate concentrations produced during thermophilic anaerobic digestion. Superior effluent quality, reduced reactor volume requirements, more stable methanogenesis due to the extended solids retention time, and uncoupling of the methanogen wasting from the refractory sludge wasting process resulted in stable and efficient processing at both temperatures for the innovative ADEPT design. Because the higher amounts of volatile fatty acids produced in the acid elutriation phase of the ADEPT system can be a favorable carbon source for biological nutrient removal in wastewater treatment plants, this positive aspect should be considered in future applications of the ADEPT system.     

Effect of acidic additives on the structure and performance of TiO2 films prepared by a commercial nanopowder for dye-sensitized solar cells

This work comprises an experimental study on the effect of various dispersing agents on the morphology of mesoporous TiO₂ films prepared by the doctor blade method and on the performance of the resulting dye-sensitized solar cells. TiO₂ films were prepared using a commercial nanopowder, Degussa P25, which was ground in a mortar, with different dispersing agents and under continuous grinding, in order to break the large agglomerates (>1 μm), present in the powder. These additives can be different acids or bases and must prevent also re-agglomeration of the nanoparticles, by forming a surface charge.Two strong acids (hydrochloric, HCl and nitric, HNO₃), a weak one (acetic acid, CH₃COOH) and a ketone (acetylacetone, C₅H₈O₂) were used in turn. The properties of the films were dependent on the concentration and the kind of the acid. With increasing concentration the coagulation of the nanoparticles also increases, thus affecting the efficiency of the devices. Of all the additives used, HNO₃ gave the best results and a 40% increment in efficiency was observed, compared to the standard dispersing agent that is acetylacetone. The improved homogeneity of the nanoparticle size (24 nm for anatase and 21.5 nm for rutile) and the better connectivity between them were responsible for the improvement in efficiency.     

Study of Proton Leakage at Interface of Anion-Exchange Membrane in Solutions of Acids,Salts, and Solvents Using Current/Voltage Characteristics

Water dissociation and proton leakage using the anionic exchange membrane (AMH) are studied by means of current/voltage characteristics and confirmed by simulation of transport number using Hittorf's method. The acids used are HCl, HNO₃, and H₂SO₄ and the salts are NaCl, ZnCl₂, and NaNO₃. Concentration polarization of such membrane is accompanied by a change in the electrolyte concentration/solution interface due hydrolysis reactions. The results show that when the concentration of the electrolyte increases, the limiting current density increases linearly and the transmembrane resistance decreases systematically. The thickness of the diffusion layer is always higher in presence of acid than salt, making in evidence the proton leakage through the membrane. Besides, when the membrane is selectively permeable to chloride anion in the case of ZnCl₂, the thickness of the double layer is rather bigger and far exceeds that of the membrane. The voltamperometry method seems reliable and offers some advantages over that of Hittorf because it shows the effects of some parameters on the value of limiting current: concentration, counter-ion types (Cl^?, NO₃^? SO₄^2?), and the gradient of concentration in the anode and cathode compartments. It can, therefore, allow to optimize the value of the current which should be used in electrodialysis in any form and without a great consumption of energy. Moreover, the simulation carried out for transport number of proton, shows its sensitivity toward the variation in concentration in the receiving compartment. In effect, a small decrease in concentration implies an enormous decrease in its value.     

Casamino Acids and Oxyrase enhance growth of Listeria monocytogenes in multi-pathogen enrichments

Rapid methods have been developed as relatively faster alternatives to plate culture for the detection of pathogenic bacteria in foods. However, since most rapid methods are subject to logistical limitations (e.g., sample volume size, analysis time, matrix effects) and/or a detection scheme with insufficient sensitivity needed to detect very low levels of bacteria in foods, culture enrichment is often employed to increase the concentration of targeted pathogens prior to detection. Multiplexed rapid detection platforms, capable of simultaneous detection of different bacteria in a single sample, necessitate co-enrichment (or mixed culture enrichment) of as many different targeted microorganisms as possible in a timely manner. This investigation compares the growth of four major foodborne pathogens (Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enterica, and Yersinia enterocolitica) inoculated into pristine media or ground pork and enriched in various culture media. Initial results revealed that, after 24 h incubation, the growth of L. monocytogenes (the slowest-growing pathogen examined) was increased by approximately 1-log by the supplementation of Universal Preenrichment Broth with Casamino Acids and/or Oxyrase. Overnight (24 h) growth of L. monocytogenes in ground pork enrichment cultures was enhanced up to ca. 2-log by the addition of either Casamino Acids or Casamino Acids and Oxyrase for each of the tested growth media. Ultimately, an overnight culture of the inoculated pathogens in any of the selected media containing both Casamino Acids and Oxyrase was observed to yield target bacterial concentrations that were at sufficient levels (between 10e5 and 10e6 CFU/mL) for detection by most rapid methods.     

碱／表面活性剂复合驱油体系与胜利孤东原油间协同效应的研究

考察了碱／非离子表面活性剂ＯＰ１０＋石油磺酸盐Ｃｙ体系与胜利孤东原油及萃取其酸性组分后的剩余油间的动态界面张力特性，发现复合驱油体系中的外加表面活性剂、碱与原油原位生成的表面活性物质之间存在明显的协同效应。这种协同效应对低离子强度下短时间内的界面张力影响较大；外加表面活性剂对高离子强度下长时间的界面张力影响较大。动态界面张力的最低值与界面上各表面活性物质的浓度和比值有着十分重要的关系