Classical chemical sciences
The inhibition efficiency of glycine-Zn2+ system has been evaluated by weight loss method and polarization study. Glycine alone has some corrosion inhibition efficiency (IE). In presence of Zn2+, IE increases. Synergistic effects exist between Zn2+ and glycine. The formulation consisting of 250 ppm of glycine and 50 ppm of Zn2+ has 86% IE. Polarization study reveals that this system function as mixed inhibitor system, controlling the anodic reaction and cathodic reaction to an equal extent.
Keywords: Corrosion inhibition, mild steel, polarization studies, glycine, zinc2+
The inhibition efficiency (IE) of trisodium citrate (TSC)-Zn2+ system in controlling corrosion of mild steel in well water has been evaluated by weight loss method. A synergistic effect exists between TSC and Zn2+. The formulation consisting of 50 ppm of TSC and 25 ppm of Zn2+ provides 87% of IE. FTIR spectra reveal that the protective film consists of Fe2+-TSC complex and Zn(OH)2. Polarization of study confirms the formation of a protective film on the metal surface .The inhibitor system controls the cathodic reaction predominantly.
Keywords: Corrosion inhibitors, well water, synergistic effect, trisodium citrate
A rapid and efficient method for the preparation of some new pyrimidine, pyrazoline and isoxazoline derivatives by the reaction of chalcones with hydroxylamine, urea and hydrazine hydrate under microwave exposure has been reported. The products have been isolated, purified and characterized by spectral methods like IR, NMR and mass spectrometry. The antibacterial and antifungal activities of the final products against various bacteria and fungi have also been reported.
Keywords: Microwave irradiation, Chalcones, Isoxazoles, Pyrazoles, Pyrimidines
The molar solubility of sodium oxalate (Na2Ox) in mixed ethanol (EtOH) – water solvent mixtures were measured at 301.15 K. From the molar solubilities, the activity coefficients, solubility products, free energies of solvation and the transfer free energies for the interaction of (Na2Ox) in mixed (EtOH-H2O) solvents were evaluated.
Keywords: molar solubility, sodium oxalate, free energies of solvation, water and ethanol
Molecular dynamics simulations were performed on ethanol–water–Pt system for studying the structural and diffusion behaviour of both ethanol and water molecules on the surface of Pt (111). This work is concerned with the differences between pure liquids and solutions in their diffusional behaviour. The self-diffusion coefficients and activation energies of diffusion of pure ethanol and water on Pt (111) surface were calculated and compared with the corresponding values of their mixtures. The results showed that the values of both the diffusion coefficients and activation energies are strongly affected by the purity of chemical species under investigation. A comparison between two different metal surfaces was also investigated and the results revealed that the nature of metal surface has a strong effect on the adsorption and diffusional behaviour of liquids based on their affinity towards a specific type of surfaces in addition to the hydrophobicity and hydrophilicity of the metal surface.
Keywords: Molecular dynamics simulation, Ethanol, Water, Pt (111), Diffusion coefficient, Activation energy of diffusion
A new series of five complexes of oxovanadium(IV) with the general formula [VO(mac)]SO4 (where mac = tetraazamacrocyclic ligands derived by condensation of 1,1’-oxalyldiimidazole with 1,2-diaminopropane and their reactions with β-diketones) have been prepared using oxometal ion as kinetic template. The prepared complexes have been characterized on the basis of electrical conductance, molecular weight, magnetic moment, elemental analyses, infrared, e.s.r. and electronic spectral data. The probable coordination number of central metal is five (distorted square-pyramid).
Keywords: oxovanadium(IV), amines, kinetic template, macrocyclic complexes
A convenient and environmentally benign silica-supported 2,4,6-trichloro-1,3,5-triazine (Silica-TCT) catalyzed Hantzsch multicomponent reaction has been shown between aldehydes, 1,3-dicarbonyl compounds and ammonium acetate in combination with stirring at room temperature under solvent-free condition to yield 1,4-dihydropyridines. Use of Silica-TCT catalyst gives several advantages in terms of simple reaction procedure, no need of organic solvent, mild reaction conditions giving quantitative yield of desired product.
Keywords: 1,4-dihydropyridines, silica-TCT, ethyl acetoacetate, substituted benzaldehyde, solvent-free
The inhibition efficiency (IE) of various concentrations of a TIPA(triisopropanolamine)-TSC(trisodium citrate)-Zn2+ system in controlling corrosion of mild steel immersed in aqueous solution containing 60 ppm Cl- was evaluated by a weight loss study. The formulation consisting of 100 ppm of TIPA and 50 ppm of Zn2+ showed 62% inhibition efficiency. When TSC (250 ppm) is added the inhibition efficiency increases to 100%. In the presence of TSC has excellent inhibition efficiency. Polarization studies reveal that TIPA-TSC-Zn2+ function as an anodic inhibitor. AC impedance spectra suggest that a protective film is formed on the metal surface. FTIR spectra reveal that the protective film consists of Fe2+ - TIPA, Fe2+ - TSC complex and Zn(OH)2.
Keywords: Electrochemical study, Corrosion inhibition, Triisopropanolamine, Trisodium citrate, FTIR spectra
From the commercial extract of the leaves of Stevia rebaudiana, a diterpene glycoside was isolated which was characterized as 13-[(2-O-β- D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-(2-O-β-D-glucopyranosyl-β-D-glucopyranosyl) ester (1); also known as rebaudioside E. The complete 1H and 13C NMR assignments of rebaudioside E was achieved by the extensive 1D and 2D NMR (1H and 13C, COSY, HMQC, HMBC) as well as mass spectral data. Further, hydrolysis studies were performed on rebaudioside E using acid and enzymatic studies to identify aglycone and sugar residues in its structure.
Keywords: stevia rebaudiana, compositae, asteraceae, rebaudioside A, spectral data, chemical studies
Materials and environmental chemistry
Since China carried out natural forest protection project in 1998, the trimber supply in China depends mainly on international market. In order to solve the problem of the supply and demand of wood in China, the fast-growing plantations of aspen wood, eucalyptus, Chinese fir, and masson pine have been explored in China. The functional modification must be performed to make better due to the low quality of these kinds of plants species. The advances in wood functional modification, such as colour processing, softening, size stabilization, strengthening, fire-retardant treatment and preservative treatment in latest 10 years, has been summarized in the present paper.
Keywords: Wood; functional modification; development trend.
Although Zn2+ and Cd2+ ions in waters are pollutant with a large amount due to mining and industrial activities, information relating to the use of marine microalgae Nannochloropsis salina to absorb both types of metals is still very little. A marine microalga, N. salina, was used as biosorbent for the metal ions in water. Concentration of each ion (Zn2+ and Cd2+) was 10 mg L–1 and the concentration ratio of Zn2+ to Cd2+ in the two-metal system (a combination of Zn2+ and Cd2+ in the culture medium) was 1:1. Experimental conditions were as follows: salinity = 25 ‰, temperature = 20 ºC, and pH = 7. Addition of each ion individually or the combination of ions was conducted when the optimum growth of microalgae was achieved (i.e. at the 8th day after cultivation). The N. salina growth after the exposure of metal ions was observed daily and the metal ion concentration adsorbed was determined by using atomic absorption spectrophotometer. Results showed that N. salina can be used as biosorbent for Zn2+ and Cd2+ both in single metal ion and two-metal system. Biosorption of Zn2+ by N. salina was higher than that of Cd2+ in the single metal ion. The amount of Zn2+ adsorbed in the two-metal system was higher than the one in the single metal ion. However, the opposite trend was observed in the case of Cd2+ ion.
Keywords: Nannochloropsis salina, zinc, cadmium, two-metal system, Conwy, biosorption
The construction and electrochemical response characteristics of poly(vinyl chloride) (PVC) membrane sensors for the determination of cetirizine drug were described. These sensors were based on the use of the ion-association complexes of the cetirizinium cation (Cet+) with phosphomolybdic acid [H3Mo12O40] (PMA) (sensor I), tetraphenylborate (TPB) (sensor II) and ammonium reineckate (NH4)2[Cr(NCS)4(NH3)2](sensor III) counter anions as ion-exchange sites in a PVC matrix plasticized with dioctylphthalate (DOP). The sensors revealed fast, stable and Nernstian response between 9.0x10-7 - 1.0x10-3 mol L-1 and 5.2x10-6 - 1.0x10-3 mol L-1 with slope of 59.3±0.2, 60.6±0.3 and 61.5±0.2 mV and dection limits 5.3x10-7, 3.8x10-6 and 5.2x10-6 mol L-1 for sensor I, II and III respectively. The intrinsic characteristics of the detectors in a low dispersion manifold under hydrodynamic mode of operation are determined and compared with data obtained under batch mode of operation. Validation of the method reveals good performance characteristics including long life span, good selectivity for Cet+ over a wide variety of other organic compounds, long term stability, high reproducibility, fast response, low detection limit, wide measurement range, acceptable accuracy and precision. Applications of the sensors for the determination of Cet+ in pharmaceutical samples were also reported. The sensors offered several advantages over many of those previously described and were amenable for quality control/quality assurance assessment of the homogeneity, stability and purity of ephedrine drug tablets.
Keywords: Cetirizine; Potentiometric sensors; Flow injection; Pharmaceutical analysis
In this research, biomaterial wastes such as spent black tea leaves (SBTL) spent green tea leaves (SGTL) as well as sawdust (SD) obtained from Narra wood were used to remove sodium dodecyl sulfate (SDS) from aqueous solutions. The effect of pH, temperature, amount of adsorbent and initial concentration of SDS has been examined. The result indicated that the SDS can be significantly adsorbed by the used biosorbents at their natural pH values. Equilibrium and kinetics studies were carried out for the adsorbents to assess the adsorption equilibrium model that they followed. The correlation coefficients were determined by linear regression analysis, and compared. The removal efficiency, maximum adsorption capacity and cost were the prime parameters for the selection of the adsorbents in this study. Among the examined adsorbents and considering all parameters, SBTL showed the higher performance for SDS removal.
Keywords: removal of anionic surfactants, spent tea leaves, thermodynamic, kinetic, isotherms
Industrial and engineering chemistry
Nowadays environmental issues due to emission of greenhouse gases such as CO2 are discussed. CO2 capture has also been introduced. Large amount of CO2 is discharged from Chinese coal fired electric power generation, so CO2 capture is mainly studied in order to protect the environment. Four types of CO2 capture technologies such as decarbonation before burning, CO2 capture after burning, oxygen-rich technologies and chemical looping combustion have been discussed. CO2 capture is improved by using the above methods. The complete development of CO2 capture technologies has resulted in good economic and social benefits around the world.
Keywords: CO2; capture; coal fired electric power generation; china
Synthetic methods of benzyl acetate using different catalysts such as strong acid cation exchange resins, inorganic salts (the weight ratio of FeCl3 to carbon (46 %) and Fe2(SO4)3), inorganic acids (H2SO4) heteropoly compounds ((NH4)6[MnMo9O32]·8H2O), heteropolyacids (phosphotungstic acid), solid superacids (S2O8 2- - Fe2O3 - ZnO, S2O8 2- - Fe2O3 - CoO, S2O8 2- - ZrO2 - Al2O3, SO4 2- - Al2O3, SO4 2- - ZrO2 - Nd2O3 and SO4 2-- MoO3 - TiO2), organic salts (tris(trimethylsilylmethylene)tin chloride) and ionic liquids (N-methylpyrrolidone hydrosulfate and 1-methyl-3-(3-sulfopropyl)imidazolium tungstophosphate) have been reviewed. The above mentioned catalysts improved the yield of benzyl acetate. These methods have the advantage of simple process and low investment costs.
Keywords: overview; synthetic methods; benzyl acetate; catalysts