Application of ZnO nanorods loaded on activated carbon for ultrasonic assisted dyes removal: Experimental design and derivative spectrophotometry method.

A method based on application of ZnO nanorods loaded on activated carbon (ZnO-NRs-AC) for adsorption of Bromocresol Green (BCG) and Eosin Y (EY) accelerated by ultrasound was described. The present material was synthesized under ultrasound assisted wet-chemical method and subsequently was characterized by FE-SEM, TEM, BET and XRD analysis. The extent of contribution of conventional variables like pH (2.0-10.0), BCG concentration (4-20mgL(-1)), EY concentration (3-23mgL(-1)), adsorbent dosage (0.01-0.03g), sonication time (1-5min) and centrifuge time (2-6min) as main and interaction part were investigated by central composite design under response surface methodology. Analysis of variance (ANOVA) was adapted to experimental data and guide the best operational conditions mass by set at 6.0, 9mgL(-1), 10mgL(-1), 0.02g, 4 and 4min for pH, BCG concentration, EY concentration, adsorbent dosage, sonication and centrifuge time, respectively. At these specified conditions dye adsorption efficiency was higher than 99.5%. The suitability and well prediction of optimum point was tested by conducting five experiments and respective results revel that RSD% was lower than 3% and high quality of fitting was confirmed by t-test. The experimental data were best fitted in Langmuir isotherm equation and the removal followed pseudo second order kinetics. The experimentally obtained maximum adsorption capacities were estimated as 57.80 and 61.73mgg(-1) of ZnO-NRs-AC for BCG and EY respectively from binary dye solutions. The mechanism of removal was explained by boundary layer diffusion via intraparticle diffusion.

Procedure optimization for green synthesis of silver nanoparticles by aqueous extract of Eucalyptus oleosa.

The present study is dealing with the green synthesis of silver nanoparticles using the aqueous extract of Eucalyptus oleosa as a green synthesis procedure without any catalyst, template or surfactant. Colloidal silver nanoparticles were synthesized by reacting aqueous AgNO3 with E. oleosa leaf extract at non-photomediated conditions. The significance of some synthesis conditions such as: silver nitrate concentration, concentration of the plant extract, time of synthesis reaction and temperature of plant extraction procedure on the particle size of synthesized silver particles was investigated and optimized. The participations of the studied factors in controlling the particle size of reduced silver were quantitatively evaluated via analysis of variance (ANOVA). The results of this investigation showed that silver nanoparticles could be synthesized by tuning significant parameters, while performing the synthesis procedure at optimum conditions leads to form silver nanoparticles with 21nm as averaged size. Ultraviolet-visible spectroscopy was used to monitor the development of silver nanoparticles formation. Meanwhile, produced silver nanoparticles were characterized by scanning electron microscopy, energy-dispersive X-ray, and FT-IR techniques.

Heterogeneous degradation of precipitated hexamine from wastewater by catalytic function of silicotungstic acid in the presence of H2O2 and H2O2/Fe2+.

The industrial wastewater produced by hexamine plants is considered as a major environmental polluting factor due to resistance to biodegradation. So the treatment of such wastewater is required. In this work, the removal of hexamine from wastewater and its degradation have been studied. Hexamine was precipitated through formation of an insoluble and stable compound with silicotungstic acid. The oxidative heterogeneous degradation of precipitated hexamine was carried out with hydrogen peroxide (H(2)O(2)) aqueous solution and H(2)O(2)/Fe(2+) under the catalysis of silicotungstic acid. The operating conditions including amount of precipitate, hydrogen peroxide and ferrous ion dosage, temperature, time and pH were optimized by evaluating the removal of total organic carbon from system. A total organic carbon conversion higher than 70% was achieved in the presence of H(2)O(2)/Fe(2+). The experimental results showed that hexamine can be effectively degraded with H(2)O(2) and H(2)O(2)/Fe(2+) under the catalysis of silicotungstic acid. It was interesting that the solution of dissolved precipitate with H(2)O(2) can re-react with hexamine after the removal of excess hydrogen peroxide. This observation indicates the catalysis role of silicotungstic acid in the degradation of hexamine. A kinetic analysis based on total organic carbon reduction was carried out. The two steps mechanism was proposed for the degradation of hexamine.

Application of Sephadex LH-20 for Microdetermination of Dopamine by Solid Phase Spectrophotometry.

A sensitive spectrophotometric method for the determination of dopamine was carried out without any separation steps. Bromocresol green is adsorbed on Sephadex LH-20 gel but the sorption decreases in the presence of dopamine due to ion-pair formation between bromocresol green and dopamine in solution. This attenuation was used to the microdetermination of dopamine by measurement of absorbance of the solid phase (Sephadex LH-20 gel) in a 1.0 mm cell at 625 nm. Dopamine could be determined in the concentration range of 0.4-1.6 µg mL(-1) (10-mL Sample volume) with a relative standard deviation (RSD) of 0.03% (n = 4). The detection limit was obtained, 0.26 µg mL(-1) (1.7 µM). The method was used for determination of dopamine in pharmaceutical injection sample and satisfactory result was obtained.

Bis[1,3-bis-(2-cyano-phen-yl)triazenido]mercury(II).

In the title compound, [Hg(C(14)H(8)N(5))(2)], the central atom is four-coordinated by two bidentate 1,3-bis-(2-cyano-phen-yl)triazenide ligands in a distorted square-planar geometry. The asymmteric unit is composed of one ligand molecule and one Hg(II) ion, which is disordered over two sites, one lying on an inversion center and the other on a general position with site-occupancy factors of 0.2378 (7) and 0.3811 (7), respectively. The monomeric mol-ecules of the complex are linked into pairs through non-classical C-H⋯N hydrogen bonds. The resulting dimeric units are assembled by translation along the crystallographic c axis into chains linked through secondary π-π inter-actions [centroid-centroid distances = 3.685 (2) and 3.574 (2) Å], as well as C-H⋯π stacking inter-actions, resulting in a two-dimensional architecture.