Removal of sulphate and phosphate from aqueous solutions using a food grade polysaccharide as flocculant

The mucilage extracted from the seeds of Tamarindus indica pods, a food grade natural polysaccharide, is used as a flocculant for removal of sulphate and phosphate ions in aqueous medium. The maximum removal obtained was 73.71% for sulphate ions and 75.71% for phosphate ions after 30 min. The optimum mucilage dose was 50 mg/L for both sulphate and phosphate ions. The maximum removal was obtained at acidic pH for both the ions. A series of contact time experiments were conducted to assess the system variables such as concentrations of mucilage and ions and pH. The conductivity measurements were also done and correlated with the percent removal. This eco-friendly food grade polysaccharide was proved to be a very good flocculant for the removal of sulphate and phosphate ions.     

Biosorption kinetics, thermodynamics and isosteric heat of sorption of Cu(II) onto Tamarindus indica seed powder

Biosorption of Cu(II) by Tamarindus indica seed powder (TSP) was investigated as a function of temperature in a batch system. The Cu(II) biosorption potential of TSP increased with increasing temperature. The rate of the biosorption process followed pseudo second-order kinetics while the sorption equilibrium data well fitted to the Langmuir and Freundlich isotherm models. The maximum monolayer Cu(II) biosorption capacity increased from 82.97 mg g(-1) at 303 K to 133.24 mg g(-1) at 333 K. Thermodynamic study showed spontaneous and endothermic nature of the sorption process. Isosteric heat of sorption, determined using the Clausius-Clapeyron equation increased with increase in surface loading showing its strong dependence on surface coverage. The biosorbent was characterized by scanning electron microscopy (SEM), surface area and porosity analyzer, X-ray diffraction (XRD) spectrum and Fourier transform infrared (FTIR) spectroscopy. The results of FTIR analysis of unloaded and Cu(II)-loaded TSP revealed that -NH(2), -OH, -C=O and C-O functional groups on the biosorbent surface were involved in the biosorption process. The present study suggests that TSP can be used as a potential, alternative, low-cost biosorbent for removal of Cu(II) ions from aqueous media.     

Converting red mud wastes into mesoporous ZSM-5 decorated with TiO2 as an eco-friendly and efficient adsorbent-photocatalyst for dyes removal

Red mud wastes have been converted into mesoporous zeolite socony mobile-5 (ZSM-5) followed by deposited titanium dioxide (TiO₂) nanoparticles to generate synergy adsorption-photodegradation for removal of dye removal in waste water. The amount of TiO₂ loading was varied to achieve optimum photocatalytic activity while maintaining the mesoporosity and high surface area of ZSM-5. Sol-gel method facilitated the formation of anatase TiO₂ on the ZSM-5. The fourier transform infrared spectra clarified the formation of Si–O–Ti at 957 cm^?1 by the exchanging the hydrogen ion with titanium ion, which proved by decreasing the absorption band of Si–OH and Si–O interaction at 964 and 944 cm^?1, respectively. Sol-gel method also preserved the mesopore diameter of ZSM-5 at 3.5 nm which allow the diffusion of methylene blue (MB) molecules into the pores. However, the surface area and the pore volume were slightly reduced with increasing the TiO₂ loading. The adsorption performance of samples showed that the increasing in the TiO₂ loading led to the decreasing in the adsorption capacity. All samples showed the suitability towards the pseudo second order kinetic. The Langmuir isotherm was suitable to describe the adsorption mechanism by monolayer adsorption. Mesoporosity of ZSM-5 accelerated the adsorption of dye via the increase of mass transfer in the pore channel which confirmed by the low intercept of intraparticle diffusion model at the first stage. The photocatalytic test showed that 10% TiO₂ loading on the ZSM-5 exhibited the highest methylene blue removal followed by 5% and 20% TiO₂ loading. Optimization on the amount of photocatalyst and the pH of solution indicated the reaction favoured 1 g L^?1 of catalysts and at alkaline pH. 10% TiO₂/ZSM-5 also exhibited high stability and reusability up to four reaction cycles. Photocatalytic performance of 10% TiO₂/ZSM-5 was further investigated on photodegradation of malachite green and rhodamine B organic dyes, which showed the photocatalytic efficiency of 73 and 88%, respectively. Superoxide radical, hydroxyl radical, and photogenerated electron were identified as the main active species for MB photodegradation based on the reduction of degradation rate following the addition scavenger molecules.     

Analysis of dimeric cyanine–nucleic acid dyes by capillary zone electrophoresis in N,N-dimethylacetamide as non-aqueous organic solvent

A method based on capillary zone electrophoresis is presented for the determination of the purity of commercial dimeric cyanine dyes (TOTO, YOYO, BOBO, all -1 and -3 species, LOLO-1, POPO-1) that are common as fluorescent probes for nucleic acid staining. These dyes are tetracharged cations, and have a strong tendency to interact with negatively charged centres, where they are rapidly adsorbed, especially from aqueous solutions. Thus anionic sites at the capillary wall must be avoided, and aqueous buffers are not suitable. The method introduced here avoids both complications, using non-aqueous N,N-dimethylacetamide as solvent, and suppressing the dissociation of silanol groups at the capillary surface due to selection of acidic separation conditions (20 mmol/l perchloric acid as background electrolyte). The present method enables the determination of the purity of all 10 dyes in less than 15 min. The selectivity of the method allows separation of at least five main and differentiating a number of unresolved minor contaminants as demonstrated in detail for TOTO-3 as an example. Quantitation (with 100% normalisation of the peak areas) of nine lots of this dye results in a purity between 33 and 87%.     

Characteristics of the pigments from anthocyan-containing food plants, raw material for production of bioflavonoid dyes

Data are presented on the composition of anthocyans of the fruits and pulp of the food plants bilberry (Vaccinium myrtillis L), high-bush cranberry (Viburnum opulus L.), elderberry (Sambucus nigra L.), cherry (Cerasus vulgaris Mill.), crowberry (Empetrum nigrum L.), cranberry (Oxycoccus palustris Pers.), currant (Ribes nigrum L.), and mulberry (Morus nigra L.) growing in the Ukraine. The anthocyan pigments differ qualitatively and quantitatively owing to genetic peculiarities in the different species of fruits and the localization of the pigments in them.Odessa State Academy of Food Technology, fax (0482) 25 32 84. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 118–120, March–April, 2000.     

Preparation of a thermosensitive cobalt phthalocyanine/N-isopropylacrylamide copolymer and its catalytic activity on thiol

A thermosensitive copolymer of cobalt tetra(N-acryliccarbonyl)aminophthalocyanine (Co-TACAPc) and N-isopropylacrylamide (NIPA) was prepared through redox polymerization in aqueous solution, and its catalytic activity for oxidation of 2-mercaptoethanol was investigated. The products of Co-TACAPc and its copolymer were characterized by elemental analysis, IR, UV/vis, and TGA. The copolymer can be dissolved into most solvents, particularly into water over a wide range of pH. The copolymer also revealed a lower critical solution temperature (LCST) phenomenon at 32.6 degrees C in water; i.e., it was soluble in cold water (below 32.6 degrees C) but insoluble in hot water (above 32.6 degrees C). As a result, in contrast to Co-TACAPc, the copolymer is able to serve as a homogeneous catalyst on oxidation of 2-mercaptoethanol below 31.0 degrees C and be recovered with increasing temperature due to its lower solubility above 31.0 degrees C.     

Determination of charge density of anionic polyacrylamide flocculants by NMR and DSC

New methods are suggested for the determination of the charge density of acrylamide/acrylate copolymers.¹³C nuclear magnetic resonance spectroscopy was used to determine the comonomer ratio by comparing the peak intensities of the methine carbon in acrylamide and acrylate monomers. Results were compared with those obtained by conductometric and potentiometric titration and were found to be in good agreement. Differential scanning calorimetry was employed to determine the glass transition temperatures (T _g) of the copolymers. A master curve was established by plottingT _g versus charge density of the copolymers previously determined by NMR and conductometric titration. Compositions of poly(acrylamide-co-acrylate) samples can thus be determined by measuring theT _g and reading the percent composition directly from the master curve.     

Toxicity assessment of nickel using Aspergillus niger and its removal from an industrial effluent

Chemical analysis of electroplating effluent revealed the presence of very high concentrations of nickel (393 ppm) in the effluent. Bioassay was carried out to test the toxicity of nickel chloride to Aspergillus niger. In contrast to 50% conidial inhibition at 1.7 mM nickel, hyphal extension was affected even at a lower concentration (0.4 mM), suggesting that hyphae are more sensitive than conidia to nickel. An increase in nickel concentration resulted in a proportionate decrease in the hyphal extension. Nickel (II)-resistant mutants of A. niger M1, M2, and M3, were obtained using direct selection, stepwise adaptation, and ultraviolet mutation techniques. Biosorption of Ni (II) by the mutant M3 was 50% more than that of its parent strain.     

Spectral study of the aggregation of benzothiazolic cyanine dyes in solutions and polymolecular layers

The formation ofJ-aggregates of three polymethine dyes in solutions and in Langmuir-Blodgett (LB) polylayers was studied. The dyes formJ-aggregates in mixtures of solvents of different polarity: hexane-chloroform and heptane-chloroform taken in various ratios. The formation ofJ-aggregates in LB polylayers depends on the type of matrix and on the matrix: dye ratio.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 96–99, January, 1995.The authors are grateful to Corresponding Member of the Russian Academy of Sciences M. V. Alfimov for valuable remarks and to Dr. A. I. Tolmachev for kindly donating samples of dyes.This work was financially supported by the Russian Foundation for Basic Research (Project No. 94-03-09182).     

Degradation of textile dyes mediated by plant peroxidases

The peroxidase enzyme from the plants Ipomea palmata (1.003 IU/g of leaf) and Saccharum spontaneum (3.6 IU/g of leaf) can be used as an alternative to the commercial source of horseradish and soybean peroxidase enzyme for the decolorization of textile dyes, mainly azo dyes. Eight textiles dyes currently used by the industry and seven other dyes were selected for decolorization studies at 25–200 mg/L levels using these plant enzymes. The enzymes were purified prior to use by ammonium sulfate precipitation, and ion exchange and gel permeation chromatographic techniques. Peroxidase of S. spontaneum leaf (specific activity of 0.23 IU/mg) could completely degrade Supranol Green and Procion Green HE-4BD (100%) dyes within 1 h, whereas Direct Blue, Procion Brilliant Blue H-7G and Chrysoidine were degraded >70% in 1 h. Peroxidase of Ipomea (I. palmata leaf; specific activity of 0.827 U/mg) degraded 50 mg/L of the dyes Methyl Orange (26%), Crystal Violet (36%), and Supranol Green (68%) in 2–4 h and Brilliant Green 54%), Direct Blue (15%), and Chrysoidine (44%) at the 25 mg/L level in 1 to 2 h of treatment. The Saccharum peroxidase was immobilized on a hydrophobic matrix. Four textile dyes, Procion Navy Blue HER, Procion Brilliant Blue H-7G, Procion Green HE-4BD, and Supranol Green, at an initial concentration of 50 mg/L were completely degraded within 8 h by the enzyme immobilized on the modified polyethylene matrix. The immobilized enzyme was used in a batch reactor for the degradation of Procion Green HE-4BD and the reusability was studied for 15 cycles, and the halflife was found to be 60 h.     

Irradiation of ferrous ammonium sulfate for its use as high absorbed dose and low-temperature dosimeter

In the present paper, we study the response of crystalline ammonium ferrous sulfate as a function of the irradiation dose and temperature. The dose studied ranged from 33.5 to 546 kGy. The temperature regimen varied from 77 K (liquid nitrogen) to 311 K. The analysis of the samples was made by UV spectroscopy and EPR.The results show that the change in absorbance of the dosimeter was linear with respect to the absorbed dose in the range studied. There is a small influence of the irradiation temperature in the response of the iron salt. The dose rate and storage time after irradiation was of no importance in this application.     

Role of the pericarp of Carya illinoinensis as biosorbent and as precursor of activated carbon for the removal of lead and acid blue 25 in aqueous solutions

The pecan nuts are widely cultivated in states of north of Mexico and the residues generated during nut processing are abundant and not reused. In the present study, the pericarp of pecan (PP) was physicochemically characterized and their use as low cost biosorbent of lead and acid blue 25 was studied in batch systems at different experimental conditions. Also, the PP was used as precursor of activated carbon and a natural modifier agent extracted from egg shells was used in the synthesis of the carbons. Results suggest that the pericarp of pecan (PP) has an acidic character due to the presence of phenolic and carboxylic groups, which play an important role in the adsorption of lead, obtaining a maximum adsorption capacity of 6 mg g⁻¹ at pH 5. But this adsorption performance was higher in the activated carbon (79 mg g⁻¹). This behavior was similar for the adsorption of AB25, indicating that carbons are more effectives in the removal of lead and AB25 than PP. The equilibrium data were fitted to Langmuir, Redlich-Peterson and Freundlich isotherm models and the Redlich-Peterson model gave a better fit for modeling our adsorption isotherms.     

Controlled drug release through poly(L-leucine) and its copolymer

The release behavior of a water-soluble drug through membranes made of poly(L-leucine) and its copolymer with different hydrophilic properties was studied. The effect of casting methods on the release rate was also investigated. It was found that the membrane with a higher hydrophilic property resulted in a higher permeation rate. The capsule was prepared as a composite sheet from a poly(L-leucine)-prednisolone 21-sodium succinate sponge and a poly(L-leucine) membrane. Release of the water-soluble drug from the capsule was found to be effectively governed by the hydrophilic character and thickness of the outer membrane. Biocompatibility studies carried out by implanting the poly(L-leucine) sponge subcutaneously in the dorsal surface of the rat showed that the sponge had a good biocompatibility and slow biodegradation. It was concluded from these results that poly(L-leucine) should be a suitable material for preparing a controlledrelease drug device for long-term dosage.     

Knoevenagel Reaction of malononitrile and its “dimer” with β-ketoanilides

The reaction of benzoylacetanilides with malononitrile has been investigated. The structure of the compounds obtained (2, 3, 4) have been assigned on the basis of chemical properties and spectral data.

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Die Knoevenagel-Reaktion von Malodinitril und seinem Dimer mit -Ketoaniliden

Zusammenfassung Die Reaktion von Malodinitril mit Benzoylacetaniliden wurde untersucht. Die Struktur der dabei erhaltenen Verbindungen (2–4) wurde auf Basis der chemischen und spektroskopischen Eigenschaften zugeordnet.

     

Synthesis, characterisation and evaluation of polydithiocarbamate resin supported on macroreticular styrene-divinylbenzene copolymer for the removal of trace and heavy metal ions

A new chelating resin was synthesised by the modification of styrene-divinylbenzene (2%) copolymer and incorporation of dithiocarbamate groups. The polydithiocarbamate resin was characterised by elemental analysis, thermal studies and IR studies. The analytical characteristics of the sorbent were established and optimum sorption conditions for Cu, Ni, Pb, Fe, As and Mn determined. The total sorption capacity of the resin was 37 mg g⁻¹ for Ni(II), 35 mg g⁻¹ for Cu(II), 29 mg g⁻¹ for Fe(III) and 23 mg g⁻¹ for Pb(II). The optimum pH for the removal of metal ions was 3-5 for Ni(II), 5 for Cu(II), 4 for Fe(III) and 4-5 for Pb(II). High sorption capacity was observed when compared with other conventional chelating polymers. The sorption kinetics was fairly rapid, as apparent from the loading half time t_1/2 values, indicating a better accessibility of the chelating sites.     

Photochemistry of benzimidazolocyanine dyes in solvents of different polarity

The effect of ion pair formation on the kinetics of the decay of the photoisomers and triplet states of cationic benzimidazolocyanine dyes is studied by flash photolysis. An increase in the rate constant of the reversecis-trans isomerization of the photoisomers is observed when ion pairs are formed (in nonpolar solvents). In the case of benzimidazolocyanine dyes with the I^– anion, ion-pair formation causes an increase in the rate constant of decay of the triplet state. Acceleration of S₁ S₀ internal conversion is discovered for the dyes with I^–1 Translated fromIvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 507–512, March, 1993.     

Intramolecular interactions I. The use of someMannich bases of naphthols as model compounds for intramolecular hydrogen bonding

Some model compounds for intramolecular hydrogen bonding are presented. The nmr, IR, UV and fluorescence spectra are shown to be suited for the study of such hydrogen bonds.

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Intramolekulare Wechselwirkungen, I. Einige Mannich-Basen von Naphtholen als Modellverbindungen für intramolekulare Wasserstoffbrückenverbindung

Zusammenfassung Eine Klasse von Verbindungen zur Untersuchung von intramolekularen Wasserstoffbrücken wird vorgestellt. NMR-, IR-, UV- und Fluoreszenzspektroskopie sind bestens geeignet, derartige Wasserstoffbrücken zu studieren.

     

Quantification of the push-pull character of azo dyes and a basis for their evaluation as potential nonlinear optical materials

The push-pull characters of a large series of donor-acceptor substituted azo dyes—71 structures in all—have been quantified by the NN double bond lengths, d_NN, the ¹⁵N NMR chemical shift differences, Δδ_15N, of the two nitrogen atoms and the quotient, π^∗/π, of the occupations of the antibonding π^∗, and bonding π orbitals of this partial NN double bond. The excellent correlation of the occupation quotients with the bond lengths strongly infers that both π^∗/π and d_NN are excellent parameters for quantifying charge alternation in the push-pull chromophore and the molecular hyperpolarizability, β₀, of these compounds. By this approach, selected compounds can be appropriately considered as viable candidates for nonlinear optical (NLO) applications.     

Derivatives of phosphorous acid as a new class of ligands for Pd-catalyzed allylation

Amido- and aminophosphites and hydrospirophosphoranes can be used as ligands in the Pd-catalyzed allylation of ethyl malonate with ethyl (3-phenylprop-2-enyl) carbonate. Bidentate ligands (RO)₂P--O(CH₂)_n--NR"₂ (n = 2 and 3) were found to be the most effective ligands.     

Mean amplitudes of vibration for PMo12O40 3− and its fragments

Mean amplitudes of vibration () are calculated for all 80 distance types in PMo₁₂O₄₀ ^3–. The values are discussed and some of them compared with the corresponding values calculated for, five different fragments of the structure. Reasonable values (<0.12 Å at 298 K) are found even for extremely long distances, e.g. 0.078 Å at 298 K for the longest oxygen-oxygen distance (10.4 Å). The values for bonded distances as well as a number of nonbonded distances have comparable magnitudes in the fragments and the whole structure; in other cases the fragment values are substantially higher.

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Mittlere Schwingungsamplituden für PMo₁₂O₄₀ ^3– und Fragmente

Zusammenfassung Mittlere Schwingungsamplituden () für alle 80 Typen von Abständen in PMo₁₂O₄₀ ^3– wurden berechnet. Die Werte werden diskutiert und einige werden mit denen von fünf verschiedenen Fragmenten der untersuchten Struktur verglichen. Es wurden auch für extrem große Distanzen plausible -Werte (<0,12 Å bei 298 K) gefunden (z. B. 0,078 Å bei 298 K für die größte, O–O-Distanz 10,4 Å). Die, -Werte für Bindungslängen und auch für einige Abstände von nicht aneinander gebundenen Atomen weisen in den Fragmenten und in der Gesamtstruktur vergleichbare Größe auf; in anderen Fällen sind die Fragment-Werte allerdings bedeutend höher.