Separation of some light monocarboxylic acids from water inbinary solutions in a reverse osmosis pilot plant

The separation of formic (C₁), acetic (C₂), propionic (C₃), and n-valeric (C₅) acids in binary water solutions has been studied using a reverse osmosis (RO) membrane pilot plant operating at different temperatures and pressures (usually 21 °C and 1.72 MPa). The RO membrane, which is composite, polyamide and spiral-wound, having a surface area of 2.6 m², was fed by a solution of 0.5 M of C₁, C₂ and C₃ acids and 0.146 M of C₅. The pilot plant was used to simulate a cascade series of RO modules by recycling the permeate flux at the end of each semi-batch run. The influence on the retention coefficient, R, of molecular weight and molar volume, pK_a of the different acids was determined. For acetic acid the influence of temperature (T) and transmembrane pressure (ΔP) was also studied, obtaining an inverse and direct good linear correlation for R vs. T and R vs. ΔP, respectively. The results are particularly interesting for acetic acid-water separation, which is an open question in industrial applications.     

Thermodynamic activity of some aqueous-organic solutions

Conclusions It has been found that the concentration dependences of the thermodynamic activity of water in aqueous-dimethylacetamide and aqueous-dimethylformamide solutions have breaks in the concentration regions of organic component of 40, 60, and 85% by wt.A comparison of the data obtained with the structure of two types of fibres for which the investigated solutions are used as precipitants indicates a parallel course for the radical changes in structure of mixed solvents of definite compositions and of fibres which are obtained under precipitation conditions.Translated from Khimicheskie Volokna, No. 2, pp. 16–17, March–April, 1990.     

Diffusion of some dyes in aqueous polymer solutions

The diffusion of both Direct Blue 76 and acid orange dyes in aqueous dilute polymer solutions was studied using the capillary method. The polymer systems studied included dilute solutions of carboxymethyl cellulose, polyethylene oxide and polyacrylamide. It was found that the diffusion coefficients of the two dyestuffs in carboxymethyl cellulose solutions are higher than that in pure water, while in polyacrylamide solutions the values of the coefficients are lower than that in pure water. In case of polyethylene oxide solutions, the diffusion coefficient of Direct Blue 76 was found to be lower than that in pure water, whereas that of acid orange was found to be higher than that in pure water. The diffusion coefficients of both dyes were found to decrease with increasing polymer concentration in the case of polyethylene oxide and polyacrylamide, whereas in the case of carboxymethyl cellulose the diffusion coefficients increased with polymer concentration. With change of temperature, the diffusion coefficients of both dyes in the three polymer solutions were found to obey the Arrhenius equation. The activation energy for diffusion of the two dyes was calculated in pure water, as well as in the different polymer solutions.     

Electrokinetic and rheological properties of Na-bentonite in some electrolyte solutions

Electrokinetic and rheological properties of Na-bentonite suspensions were investigated in the presence of various electrolyte solutions including LiCl, NaCl, KCl, NH₄Cl, NaClO₄, CH₃COONa, NaNO₃, Na₂SO₄, Na₃PO₄, CuCl₂, MnCl₂, CaCl₂, BaCl₂, NiCl₂ and AlCl₃. It was found that divalent cations (Cu²⁺, Mn²⁺, Ca²⁺, Ba²⁺ and Ni²⁺) and trivalent cation (Al³⁺) were potential determining cations for the Na-bentonite suspensions. Trivalent cation, Al³⁺, changed the surface charge of Na-bentonite from negative to positive. The zeta potential measurements showed that monovalent counter-cations and mono-, di- and tri-valent anions were indifferent ions for the Na-bentonite suspensions. The plastic viscosity and the Bingham yield stress values of the Na-bentonite suspensions were also determined in the presence of electrolyte solutions.     

Density of solutions of formaldehyde in water and alcohols

Formaldehyde is an important chemical that is mostly handled in aqueous solutions, which generally also contain methanol; furthermore, also solutions of formaldehyde in other alcohols are used. The density of these solutions is an important thermophysical property. The available models of the density of formaldehyde-containing solutions, however, all have shortcomings, such as a poor accuracy or a limited range of applicability. Therefore, in the present work, a new model of the density in systems of the type (formaldehyde + water + alcohol) was developed. The alcohols that are presently included in the new model are methanol, 1-propanol, and isoprenol; an extension to other alcohols is straightforward. The model was developed using literature data and extensive new density data measured in this work covering binary, ternary, and quarternary solutions of formaldehyde in water, methanol, 1-propanol, and isoprenol at temperatures of $283-333$ K and formaldehyde concentrations of 0.06 − 0.30 g g⁻¹.     

焦化废水处理过程中常见问题及控制措施

济钢焦化废水处理采用AAOO-混凝沉淀-芬顿氧化工艺。分析了废水处理系统在运行过程中出现的污泥老化、污泥中毒等常见问题以及相应的控制措施。     

Viscosity of sea water solutions

The kinematic viscosity of sea water solutions and concentrates up to 11% salt by weight and from 0 to 200°C have been measured in a pressurized glass capillary viscometer. All precipitation was prevented during testing; carbonates and hydroxides by slight acidification (to pH 4.5) with concentrated (36N) sulfuric acid, and calcium sulfate by preheating and filtration under pressure. The precision of the results is ± 0.001 centistokes. Existing data on density of sea water solutions were correlated and used to calculate the dynamic viscosity in centipoises. Smoothed values presented should be accurate to ± 0.003 centipoises above 20°C and ± 0.005 below 20°. The results compare well with other authors' values for synthetic sea water.     

Degradation of crosslinked resins in water and electrolyte solutions

In addition to chemical processes such as the hydrolysis of ester groups, there are physical processes contributing to the hygrothermal degradation of crosslinked polyester resins. This paper discusses the interaction between physical and chemical processes and reports short and long term observations on the degradation of several resins of various compositions during immersion in aqueous liquids. Initial swelling is accompanied by weight changes which are the result of (i) absorption of water (ii) leaching of non-bound substances and (iii) leaching of hydrolysis products. Leached substances are identified qualitatively by n.m.r. spectroscopy and, in some cases, semi-quantitatively by gas-liquid chromatography (g.l.c.). Osmotic disc cracks greatly accelerate the hydrolysis process and appear to be caused mainly by the presence of residual or added glycol in the resins. (These cracks were almost entirely absent from a vinyl ester resin). Scanning and high resolution transmission electron micrographs demonstrate the nature and extent of surface physical damage by water.     

Electrochemical behaviour and corrosion of lead in some carboxylic acid solutions

The electrochemical behaviour and corrosion of lead in various concentrations of acetic, lactic (0·01 M –1·0 M ), oxalic and tartaric (0·01 M –0·15 M ) acid solutions were studied at 25°C by a potentiodynamic method. The lead anode is readily soluble both in acetic and lactic acid solutions up to 2000 mV. In these two acid solutions, the anodic dissolution of lead increases with increases in the acid concentration and the dissolution process is under charge transfer control. Lactic acid is more corrosive than acetic acid. However, in oxalic and tartaric acid solutions, the E/i profiles depend on the acid concentration. Above a certain specific concentration, the profiles exhibit an anodic current peak associated with a dissolution of the metal and the formation of a passivating lead salt film and a cathodic peak which is related to the reduction of the film. The active dissolution of the lead increases with the acid concentration, the scan rate and stirring of the solution. The passivation of lead in these two acid solutions occurs by a dissolution–precipitation mechanism and the process is controlled by diffusion. X-ray diffraction analysis confirmed the presence of a passivating salt film (either lead oxalate or lead tartrate) on the electrode surface. © 1998 SCI     

电泳系统中若干常见问题的分析及解决措施

分析了电泳涂装系统中的若干常见问题,包括滤袋堵塞、槽液循环、产生泡沫、阳极系统问题、超滤系统问题、细菌污染和烘房固化问题等。探讨了问题产生的原因并给出了相应的解决措施。     

Activity and stability ofPenicillium cyclopium lipase in surfactant and detergent solutions

Activity and stability of an alkaline lipase fromPenicillium cyclopium var.album (PG 37) were studied in surfactant and detergent solutions. Three anionic surfactants [Na salts of C₁₂SO₄ ^? (sodium dodecyl sulfate), C₁₂ØSO₃/^? (linear alkyl benzene sulfonate), and C₁₁COO^? (laurate)] and four homologous series of nonionic surfactants of C_12–15 polyoxethylenated fatty alcohols (AEO₃, AEO₅, AEO₇, and AEO₉) were evaluated. At a concentration range of 3.2–40 μM, sodium dodecyl sulfate and laurate stimulated the activity of PG 37 lipase. At concentrations greater than 5.6 μM, linear alkylbenzene sulfonate inhibited PG 37 lipase activity. Nonionic surfactants, AEO₅ and AEO₇, in the concentration range of 0.25–20 mM, enhanced and stabilized the activity of PG 37 lipase. The presence of PG 37 lipase in detergent formulaton improved detergency ～20%. The mechanism of inhibition of the lipolytic activity of PG 37 lipase is proposed to be partly due to the formation of inactive (BR)_n-E complex between the hydrophobic moiety of the surfactants and the surface of the lipase. Conversely, formation of a soluble (RB)_n-E complex between the hydrophilic group of the surfactant and lipase may account for the increased lipolytic activity of PG 37 lipase.     

Structure Determination and Anti-Inflammatory Activity of some Purine Complexes

Organomercury(II)-purine derivatives of the type, p-MeOC(6)H(4)HgL(1) (I), p-NO(2)C(6)H(4)HgCl(L(2))(II), p-MeC(6)H(4)HgCl(L(3))(III) and p-NO(2)C(6)H(4)HgCl(L(3))(IV) [ HL(1) = theophylline, L(2) = theobromine, L(3) = caffeine] have been synthesised and characterised on the basis of spectral studies (IR, UV, (1)H & (13)C NMR). The complexes have been screened for anti-inflammatory activity.     

氯水换热系统存在的问题及处理措施

针对氯水换热器换热效果不理想,且氯水管道泄漏的问题,分析了原因,并提出了解决措施。     

Semiautomatic potentiometric and coulometric determination of water in polymer solutions

Conclusions Potentiometric, titrimetric, or coulometric methods are applicable for determining the water content of solutions of PVC in DMF or in PFM.Translated from Khimicheskie Volokna, No. 3, pp. 60–61, May–June, 1983.     

Sorptional tar removal from water and solutions

Packed equipment for removing tar from water by filtration, adsorption, and coalescence is tested.     

Composition dependence of viscosity of some binary solutions

Viscosities of eleven binary liquid systems, mostly regular solutions, have been measured over the entire composition ranges at 25°C. Most of the systems had not been investigated before. The procedure, the precautions observed for the measurement of viscosity, and the calibration of the viscometers have been discussed. Of the many empirical and semi-empirical equations tested for their validity the McAllister equation has been found to fit best the experimental data for all the solutions. Non-ideality of a solution, as expressed in terms of excess activation energy for viscous flow or in terms of excess molal volume, has also been briefly discussed.     

Conductivity of some rare earth chlorides in sub and supercritical aqueous solutions

The electrical conductances of 0.001 M NdCl₃, SmCl₃, GdCl₃ and DyCl₃ solutions were measured in the temperature range 373–673 K at pressures up to 37.27 MPa, using a flow type electrical conductance cell. The cell constant was calculated by means of the measured conductance of five solutions of KCl, with concentrations range of 0.0001–0.002 M and the equivalent values calculated from Barthel equation at 298 K and was found to be equal to 0.111 cm⁻¹. By using the measured electrical conductance values, the specific conductance, σ, and the equivalent conductance, Λ, were calculated. The maximum electrical conductance was obtained in the sub critical region at ≈548 K in all cases. At this temperature, the electrical conductance was found to increase with the increase in the ionic radius from Dy to Sm. The electrical conductance of Nd was found to be smallest, which could be attributed to a higher ionic association.     

Structural transitions in liquid crystalline solutions of some cellulose derivatives

It was found that the domains of the mesophase of the investigated systems have cylindrical symmetry and a different direction of the maximum polarizability: for ethylcellulose and cellulose diacetate, the polarizability is directed along the axis of the cylinder, while it is at an angle of 45‡ for hydroxypropylcellulose. Formation of liquid-crystalline spherulites in the thermotropic transition of isotropic solutions of ethylcellulose in formic acid to the mesophase was demonstrated. In the liquid crystal—isotropic liquid phase transition, a characteristic extreme of the intensity of light scattering is observed near the region of melting of the liquid crystalline matrix, so that this method can be used for identifying the region of the existence of a two-phase “corridor”. Translated from Khimicheskie Volokna, No. 5, pp. 25–27, September–October, 1997.     

The differential capacitance of solid tantalum in some aqueous solutions

The differential capacitance of tantalum has been measured in a number of aqueous electrolyte solutions. The metal is generally covered with an oxide layer in solutions of simple inorganic anions and the electrode capacitance is 5–10 F cm^–2. In solutions of oxalate anions the electrode capacitance is much higher and corresponds to that expected for a clean metal in contact with an aqueous solution.