Estimation of the energetic parameters associated with the aerobic degradation of quinoline by Comamonas acidovorans in continuous culture

An estimation of the true growth yields and maintenance coefficients for Comamonas acidovorans DSM 6426 under continuous cultivation on quinoline has been performed. The data were checked for consistency using available electron, carbon and nitrogen balances. The true biomass energetic yields, η_max, and energetic maintenance coefficients, m_e, were estimated using two models based on control of growth rate and control of substrate uptake rate, respectively. The estimations were converted to the various familiar true growth yield and maintenance units such as substrate-based (Y, m_S/X), oxygen-based (Y, m) and carbon dioxide-based (Y, m) units. For the complete mineralization of quinoline by C. acidovorans, values of η_max = 0.371 and m_e = 0·0426 h^?1 were obtained.     

Homogeneous and heterogeneous catalytic reactions in a cobalt oxide/graphite air electrode. Part IV. Mechanistic studies on a ring-disk carbon electrode in alkaline solution

The redox properties of HCoO on a glassy carbon electrode in the absence and presence of hydrogen peroxide have been investigated by using cyclic voltammetry and UV-Vis spectroscopy in alkaline solution. Corresponding rotating ring-disk experiments showed that the disk current increased by about 60% in the presence of HCoO, confirming the important role played by HCoO in the homogeneous decomposition of hydrogen peroxide.     

Comment

Electrolytic manganese dioxide is dissolved in the mixed non-aqueous solvent dimethyl sulfoxide–sulfur dioxide (DMSO–SO₂) to form manganese disulfate as a final product. Sulfur dioxide does not change the oxidation state of the metal cations in DMSO–SO₂ solvent. However, oxidation of sulfur(IV) to sulfur(VI) is possible. The complete MnO₂ dissolution occurs in 50 min at a stirring speed of 650 rpm, pH 1, 0.2% solids concentration, 35 × 44 mesh particle size, and 36°C. IR and FTIR evidence has been presented in favor of the formation of SO, S₂O, (CH₃)₂S⁺ as intermediate species for the proposed mechanism. In the mixed non-aqueous solvent system the kinetics of leaching is controlled by a mass transport process. The equation 1–?α–(1–α)^2/3 = kt fits the experimental data very well. This is further supported by scanning electron micrographs, which show a product layer formation on the surface of the MnO₂ particle, and by the dependence of k on 1/r.     

Aniline and some of its derivatives as corrosion inhibitors for nickel in 1 M HCl solution

The inhibiting action of aniline and some of its derivatives (o‐, m‐ and p‐anisidine) towards the corrosion behaviour of nickel in 1 M HCl solution has been studied using weight loss and polarization techniques. These compounds were found to retard the corrosion rate of nickel. At constant temperature, the corrosion rate decreases with increasing inhibitor concentration. On the other hand, at any inhibitor concentration, the increase in temperature leads to an increase in the corrosion rate. The activation energy, ΔE_a, the equilibrium constant, k, as well as the other thermodynamic parameters (ΔG, ΔH and ΔS) for inhibitor process were calculated and analysed. The inhibitor efficiencies calculated from both weight loss and polarization methods are in good agreement and were found to be in the order: p‐anisidine > o‐anisidine > m‐anisidine > aniline. The inhibitive action of these compounds was attributed to the adsorption of molecular species and their inhibitive efficiencies depend on the relative position of the  OCH₃ group in the aniline ring. © 1999 Society of Chemical Industry     

Denitrifying kinetics involving the distributed ratio of reductases

A suspended-growth batch reactor was used to denitrify synthetic wastewater containing various proportions of nitrate and nitrite. A competitive phenomenon between nitrate- and nitrite-reductase was studied utilizing various proportions of nitrate and nitrite in an anaerobic environment with a temperature of 30°C and methanol as carbon source. By using a non-linear regression technique, biokinetic constants of the maximum specific reduction rates of nitrate and nitrite (k₁, k₂) and the Monod half-saturation coefficients of nitrate and nitrite (K_s1, K_s2) for the proposed two-step denitrifying kinetics were 1·29 day^?1, 0·89 day^?1 and 14·3 mg NO-N dm^?3, 10.9 mg NO-N dm^?3, respectively. The result obtained from a series of chemostat studies indicated the Monod-type kinetic model was more accurate when the distributed ratio of nitrate- and nitrite-reductase in the proposed two-step denitrifying kinetics was taken into account.     

Removal of the tetravalent actinide thorium from solution by a biocatalytic system

The aim of this work was to study the effects of pH, a metal complexing reagent (citrate) and the concentration of substrate on the bioaccumulation of tetravalent actinides, using Th⁴⁺ as a model, by a phosphates-catalysed reaction. This yields HPO which precipitates with heavy metals as cell-bound metal phosphate. Poor removal of The from solution was observed, which is in accordance with the solution chemistry of the metal. A considerable improvement in the efficiency of thorium removal was obtained by incorporating ammonium acetate (NH₄Ac) into the solution. Although extensive deposition of polycrustaling NH₄UO₂PO₄ was observed previously by cells that had accumulated UO, no evidence for deposition of cstalline thorium phosphate was obtained by X-ray diffraction analysis. Examination by proton induced X-ray emission (PIXE) analysis. Examination by proton induced X-ray emission (PIXE) analysis showed a non-homogenous thorium deposit of variable phosphorous content.     

Anaerobic biodegradability and toxicity of eucalyptus fiber board manufacturing wastewater

Wastewater from eucalyptus fiber board manufacturing (EFBM) was characterized and studied for its treatability by anaerobic digestion. The characteristics of the wastewater (in mg dm^?3), are as follows: COD (42 000), SS (550), SO (1200), PO.P (50), NH.N (15), VFA (710), phenol (20), p-cresol (125), tannin COD (1460) and pH 2.8. Approximately 60% of the COD is composed of carbohydrates. The continuous treatment of EFBM wastewater resulted in 93% COD removal and 78% COD methanogenized, with influent COD values of 20 g dm^?3 and OLR of 17 kg COD m^?3 d^?1. The biodegradation reached 94% of influent COD and 74% of influent ultraviolet absorbance (215 nm). EFBM wastewater supplied at 20 g COD dm^?3 (1:1 tap water diluted) caused 50% methanogenic toxicity, which did not disappear when tannins were removed by adsorption on PVP (polyvinylpyrrolidone). The toxicity decreased to 25% once the wastewater was autoxidized with air at high pH values. However, the effluent of the continuously fed column didn't show methanogenic toxicity, therefore the main toxic compounds in the wastewater were removed during anaerobic treatment.     

Oxidation of aqueous sulfur dioxide catalyzed by poly-4-vinylpyridine–Cu(II) complex. Part 1: Homogeneous phase oxidation

The oxidation of aqueous sulfur dioxide in the presence of polymer-supported copper(II) catalyst is also accompanied by homogeneous oxidation of aqueous sulfur dioxide catalyzed by leached copper(II) ions. Aqueous phase oxidation of sulfur dioxide of low concentrations by oxygen in the presence of dissolved copper(II) has therefore been studied. The solubility of SO₂ in aqueous solutions is not affected by the concentration of copper(II) in the solution. In the oxidation reaction, only HSO is the reactive S(IV) species. Based on this observation a rate model which also incorporates the effect of sulfuric acid on the solubility of SO₂ is developed. The rate model includes a power-law type term for the rate of homogeneous phase reaction obtained from a proposed free-radical chain mechanism for the oxidation. Experiments are conducted at various levels of concentrations of SO₂ and O₂ in the gas phase and Cu(II) in the liquid phase. The observed orders are one in each of O₂, Cu(II) and HSO. This suggests a first-order termination of the free radicals of bisulfite ions.     

Intrinsic birefringence of nylon 6

Different values are reported in the literature for the intrinsic birefringence of the crystalline (Δn) and the amorphous (Δn) phases in nylon 6. Mostly, these values have either been determined by extrapolation (and then it is assumed that Δn = Δn) or calculated theoretically. In this study, intrinsic birefringence values Δn and Δn for nylon 6 were determined using the Samuels two-phase model which correlates sonic modulus with structural parameters. Three series of fiber samples were used: (1) isotropic samples of different degrees of crystallinity for estimation of E and E moduli at two temperatures. The following modulus values were obtained: 1.62 × 10⁹ and 6.66 × 10⁹ N/m² for 28.5°C, and 1.81 × 10⁹ and 6.71 × 10⁹ N/m² for ?20°C; (2) anisotropic, amorphous fiber samples for estimation of Δn = 0.076 and E = 1.63 × 10⁹ N/m² at 28.5°C; (3) semicrystalline samples of various draw ratios for estimations of Δn = 0.089 and Δn = 0.078. All measurements were carried out with carefully dried samples to avoid erroneous results caused by moisture.     

Über die Katalyse der Cooxidation von cis-Oct-4-en und n-Butyraldehyd

The Catalysis of the Co-Oxidation of cis-Oct-4-ene and n-Butyric Aldehyde The co-oxidation of cis-oct-4-ene and n-butyric aldehyde in the absence of catalysts, or in the presence of molybdenum and Co(acac)₃, resp., was studied in dependence on the aldehyde/olefin ratio, on the temperature and other reaction conditions. Under the same conditions, the noncatalyzed co-oxidation converted 50%, the MoO₂(acac)₂-catalyzed one 68%, and the Co(acac)₃-catalyzed one 40% of the reacted olefin into the epoxide. The cis/trans-epoxide ratio in the molybdenum-catalyzed co-oxidation was nearly 2 independent of the aldehyde/olefin ratio. In the non-catalyzed co-oxidation the cis/trans-epoxide ratio depends linearly on the aldehyde/olefin ratio (cis/trans E. = 0,58 + 0,90 n/n). From these dependences we can conclude that the homolytic mechanism of epoxide formation decreases and the polar mechanism (Priležaev-reaction) increases with increasing aldehyde/olefin ratio. Optimization of the epoxide yields according to a Box-Hunter experimental plan gave the following reaction conditions to yield 95% epoxide based on reacted olefin: 70°C, Δn_S/n = 0,49, n/n = 3,5 · 10⁻³, n/n = 0,53. The co-oxidation in the presence of other molybdenum catalysts of the chloro-nitrosyl-complex type and of the carbonyl-complex type as well as the co-oxidation with other aldehydes were studied, too.     

Fotosensibilisierte Ausbleichung von Azomethinfarbstoffen

Fotosensitized Fading of Azomethine Dyes The quantum yields of photofading of the azomethine dyes 1a—h were determined in the presence of the sensitizers benzophenone (B), michler's ketone (MK) and anthracen (A), in isopropanol and benzene. In isopropanol, excluding oxygen, the leuco dyes 5 are formed by benzophenone in high quantum yield (Φ = 0.4). Photofading also takes place using Michler's ketone (Φ ≅ 3 · 10⁻³) and anthracene (Φ ≅ 1 · 10⁻⁴), but 5 was not found. With benzophenone (Φ ≅ 7 · 10⁻³), Micher's ketone (Φ ≅ 1 · 10⁻³) and anthracene (Φ ≅ 1 · 10⁻⁴) as sensitizers the chromophore of 1a—h were destroyed, when oxygen was present. The photofading with benzophenone and Michler's ketone is a result of radicalic processes. Radical scavangers 8 and 9 , therefore, give a strong decrease of the quantum yield of photofading. The photofading in benzene corresponds to the results in isopropanol considering the lower potential of this solvent for photoreduction processes.     

Elastic characteristics of branched-network polymers

The computed dependencies of elastic characteristics of branched-network polymers were obtained on the basis of the Takayanagi series model. The moduli ratio (λ) for branched-network and branched polymers increases as a result of an increase of the moduli ratio of network and branched phases (E/E) and the network phase fraction (V_net). The λ-increase as a function of V_net is larger than in the case of the E/E dependence. On the basis of computed dependencies, the experimental results for the radiation crosslinked SBS block copolymer were considered. The experimental results agree with the computed de-pendencies for the hetergeneous branched-network polymers with E/E ≈︁ 20. The influence of entanglements on the elastic characteristics of branched-network polymers is discussed. © 1996 John Wiley & Sons, Inc.     

Mass transport process for the adsorption of Cr(VI) onto water‐insoluble cationic starch synthetic polymers in aqueous systems

Dynamic adsorption behaviors between Cr(VI) ion and water‐insoluble amphoteric starches was investigated. It was found that the HCrO ion predominates over the initial pH ∼ 2–4, the CrO ion predominates over the initial pH ∼ 10–12, and both ions coexist over the initial pH ∼ 6–8. The sorption process occurs in two stages: the external mass transport process occurs in the early stage and the intraparticle diffusion process occurs in the long‐term stage. The diffusion coefficient of the early stage (D₁) is larger than that of the long‐term stage (D₂) for the initial pH 4 and pH 10. The diffusion rate of HCrO ion is faster than that of CrO ion for both processes. The D₁ and D₂ values are ∼ 1.38 × 10⁻⁷–10.1 × 10⁻⁷ and ∼ 0.41 × 10⁻⁷–1.60 × 10⁻⁷ cm² s⁻¹, respectively. The ion diffusion rate in both processes is concentration dependent and decreases with increasing initial concentration. The diffusion rate of HCrO ion is more concentration dependent than that of CrO ion for the external mass transport process. In the intraparticle diffusion process, the concentration dependence of the diffusion rate of HCrO and CrO ions is about the same. The external mass transport and intraparticle diffusion processes are endothermic and exothermic, respectively, for the initial pH 4 and pH 10. The k_d values of the external mass transport and intraparticle diffusion processes are ∼ 15.20–30.45 and ∼ −3.53 to −12.67 kJ mol⁻¹, respectively. The diffusion rate of HCrO ion is more temperature dependent than that of CrO ion for both processes. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2409–2418, 1999     

Ammoxidation of propylene by pulse reaction technique

The ammoxidation of propylene on Fe-Bi-P mixed oxide catalyst was studied at 500 °C by the pulse reaction technique, to examine the effects of P(P = 0–4) and P (P/P = 0–3) on the catalyst activity. Since the ammoxidation of propylene proceeds through consumption of oxygen from the catalyst even in the absence of oxygen, the reduction of catalyst progresses with the number of O₂-free pulse, losing its activity. In the presence of oxygen, however, the conversion of propylene and the selectivities of acrylonitrile, acetonitrile, CO₂, and CO vary with the pulse number, but settle to some steady values corresponding to P/P. It is also found that the conversion and the selectivities depend on the oxidation state of the catalyst, the latter also depending on P/P in the reactants, and that the catalyst working in the flow system may be being reduced to some extent.     

Tearing mode interlaminar fracture toughness of composite materials

The Simplified Split Cantilever Beam (SSCB) is proposed in this work and compared with the Split Cantilever Beam (SCB) to obtain the tearing mode interlaminar fracture toughness. The materials considered are single‐fiber system composites and interply hybrid composites. For interply hybrid composites, three different types of stacking sequence for SSCB specimens, which are [0/0//0],[0/0//0]. and [0/0//0], are tested to compare their suitability. Finite element analysis combined with a modified crack closure integral has been applied to separate the different components of the strain‐energy release rate. In addition, the method of compliance calibration was used to calculate Gc values. The effects of crack growth, initial crack length, specimen width, and number of glass fiber plies were also studied. The results show that SSCB testing has a more dominant Mode III component and more stable Gc values than SCB testing. For SSCB testing, the crack growth and the specimen width for the range considered have no clear effects on the interlaminar fracture toughness, but the initial crack length should be carefully selected to obtain corrected values. The tearing mode interlaminar fracture toughness of interply hybrid composites is higher than that of carbon/epoxy composites, and the three different types of stacking sequence considered are all suitable to approximate the Mode III interlaminar fracture toughness for interply hybrid composites.     

Influence of anionic form on thermal degradation of TMAHP–cellulose

Trimethylammoniumhydroxypropyl (TMAHP)–cellulose in 10 anionic forms (F^?, Cl^?, Br^?, I^?, HSO, NO, OH^?, HCO, H₂PO, CH₃COO^?) was prepared, and the influence of each anion on thermal degradation in inert atmosphere was studied. With the help of dynamic and isothermal thermogravimetry (TG) it was found that H₂PO ions had the greatest retarding effect on TMAHP–cellulose degradation. From the values of rate constants it can be seen that all ionic forms of TMAHP–cellulose have the starting rate of thermal degradation greater than unmodified cellulose. The calculated values of activation energy of thermal degradation for different ionic forms are decreasing in following sequence: H₂PO > F^? > NO > I^? > Br^? > HCO > Cl^? > HSO > OH^? > unmodified cellulose > CH₃COO^?. From the results of pyrolyse measurements in combination with gas chromatography and mass spectrometry (Py–GC–MS) it follows that the products of the elimination of quarternary ammonium salts are trimethylamine, 3-hydroxy-2-propanone, and, in the case of OH^? form, water. In all other ionic forms the third product is the corresponding acid.     

Use of thermolysin metalloprotein affinity metal chromatography in the decontamination of actinide-bearing solutions

Thermolysin metalloprotein affinity metal chromatography (MAMC) has been shown to be effective for the removal and concentration of lanthanide and actinide ions from aqueous solution. Using solution of trivalent lanthanide ions of appropriate radii and of Th⁴⁺ and UO ions as models, the calciumbinding sites of immobilized thermolysin have shown appreciable potential for the decontamination of actinide-bearing waster solutions. The zinc-binding site of the affixed protein may also be used for the removal and concentration of divalent transition metal ions.     

Several features of vinyl chloride–diallyl phthalate suspension copolymerization

Vinyl chloride–diallyl phthalate (VC–DAP) suspension copolymerization was carried out in a 5‐L autoclave and 200‐mL stainless steel vessel at 45°C. The apparent reactivity ratios of VC–DAP suspension copolymerization system were calculated as r_VC = 0.77 and r_DAP = 0.37. It shows that VC–DAP copolymer contains no gel when the feed concentration of DAP (f) is lower than a critical concentration (f_cr, inside the range of 0.466–0.493 mmol/mol VC at 80–85% conversion), the polymerization degree (DP) of copolymer increases with the increase of f and conversion. VC–DAP copolymer is composed of gel and sol fractions when f is larger than f_cr. The DP of sol fraction decreases as f increases, but the gel content and the crosslinking density of gel increase. The gel content also increases as conversion increases. The results also show that the index of polydispersity of molecular weight of sol changes with f, a maximum value appears when f is close to f_cr. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 156–162, 2000     

Mechanical properties of polyethylene/ethylene vinyl acetate filled with calcium carbonate

The tensile behavior of polyethylene/ethylene vinyl acetate (PE/EVA) polymer blends filled with calcium carbonate (CaCO₃) was studied using tensile and viscoelastic tests. The relations between tensile properties (modulus, strength, etc) of oriented and unoriented PE/EVA-CaCO₃, and void volume of polymer/CaCO₃ interface, PE/EVA blend ratio, and CaCO₃ content were investigated. The results indicated that the tensile strength and elongation of PE/EVA-CaCO₃ decreased with CaCO₃ content and PE blend ratio for unoriented PE/EVA-CaCO₃ systems. In the case of oriented samples, the relative modulus (E/E, where E and E are the modulus of oriented composites and the modulus of oriented matrix, respectively) of PE/EVA-CaCO₃ is larger than that of PE/CaCO₃ by increasing the EVA content relative to PE and CaCO₃. The value of E/E can be simply expressed as the function of void volume and CaCO₃ modulus to polymer matrix modulus.     

Synthesis and electrochemistry of grafted copolymers of cellulose with 4-vinylpyridine, 1-vinylimidazole, 1-vinyl-2-pyrrolidinone,and 9-vinylcarbazole

Some new cellulosic materials, suitable for the adsorption of noble metal ions, were syn-thesized by chemical and electrochemical modification of cellulose. The polymerizable groups were introduced in cellulose with ∼ 80% yield of substitution by esterification with acryloyl chloride. The vinyl monomers (4-vinylpyridine, 1-vinylimidazole, 1-vinyl-2-pyrrolidinone, and 9-vinylcarbazole) were readily grafted into cellulose acrylate via radical polymerization in acetonitrile. The grafted copolymers of cellulose with 4-vinylpyridine and 4-vinylimidazole were reacted with methyl iodide and the corresponding 1-methylpyridinium iodide ( 6 ) and 3-methylimidazolium iodide ( 7 ) copolymers of cellulose were obtained. Copolymers 6 and 7 were transformed into new polymeric regents, differing in anions (ClO, CF₃COO⁻, NO, p-TsO⁻, BF, PF) by using a supporting electrolyte carrying the desired anions through the ion-exchange-electrochemical oxidation of the released iodide at a controlled anodic potential. © 1996 John Wiley & Sons, Inc.