ester and N-[4-(2-amino-3-hydroxy-pyridin-6-ylazo)phenyl]-acetamide compounds were studied. The dissociation constants were determined potentiometrically. The thermodynamic parameters of dissociation were evaluated. Regression analysis is applied for correlating the different parameters. The results help to assign the solute-solvent interactions and the solvatochromic potential of the investigated compounds. The electronic character of the substituent and the chemical nature of the solvent are major factors for the observed solvatochromism. Nitroso Pyridin-6-ylazo Triazene Effect of solvents Potentiometry Spectrophotometry

Polymeric nanocomposite materials are very important materials because of their promised applications. However, many of their fundamental physical, mechanical, and chemical behaviors have not been quantified. Depending on the interface forces between polymer and clay, different configurations of polymer–clay nanocomposites exist: intercalated, flocculated, and exfoliated nanocomposites. In this paper, a study on the first two configurations is presented. Poly(vinyl alcohol) (PVA)–Cloisite® 20A was chosen for the intercalated system and PVA–Cloisite® 10A was chosen for the flocculated one. In both cases, the phyllosilicate clays used were organically modified by tallow‐triethanol‐ammonium ion. The morphology of the two systems was investigated by using X‐ray diffraction and nanoscanning electron microscopy. Although both confirmed the intercalation between PVA and 20A nanoclay, they confirmed the nonintercalation between PVA and 10A nanoclay. Another confirmation of the intercalation phenomena in PVA and 20A nanoclay was obtained from differential scanning calorimetry, which showed an increase in crystallinity upon intercalation. A main focus for the intercalated system was to study the effect of the nanoparticle's loading on the mechanical properties. Intercalation markedly affected both Young's modulus and the extent of elongation of the PVA–Cloisite® 20A nanocomposite. Young's modulus and tensile stress increased with the loading of the clay up to 2 wt%. For higher loading, opposite results were reported due to the agglomeration of nanoparticles and as a consequence of the formation of microvoids. J. VINYL ADDIT. TECHNOL., 23:181–187, 2017. © 2015 Society of Plastics Engineers

The present work aimed to study the physicochemical parameters and nutrient salts of El Mex Bay area to evaluate its composition since El-Mex Bay exposed to several kinds of human activities and receive different types of industrial pollutants. Various pollutants are dumped daily by industrial, agricultural and domestic sources over Alexandria coasts through several outfalls, El-Mex Bay one of these disposal sites (El-Mex Pumping Station). Surface and bottom water samples were collected seasonally during the period from September (summer) 2012 to April (spring) 2013. Salinity variation appeared in water quality changes, it ranged from 2.25‰ to 38.87‰ and from 26.21‰ to 39.64‰ at the surface and bottom water, respectively. Dissolved oxygen levels indicated poor aeration conditions along the water column, it is lower in most stations at surface layer (ND-3.15 mgl-1) than that in the bottom layer (0.79-6.28 mgl-1). The pH values of the study area at surface ranged (7.05-8.73), while at the bottom water ranged (7.18-8.45). Inorganic nitrogen species in El-Mex Bay water decreased in the order of NH 4 + > NO 3-> NO 2-. The measured nutrient content varied greatly as follows: NH 4 + , 4.73±5.70 to 99.27±72.53 µM; NO 2-, 0.72±0.43 to 4.34±3.43 µM; NO 3-, 1.33±1.01 to 31.68±24.59 µM Regional and seasonal variations of total nitrogen concentration in El-Mex Bay surface and bottom water ranged from 28.26± 14.87 to 335.12±226.66 µM. The concentrations of reactive phosphate (PO 4) and total phosphorus (TP) were in the ranges of 0.05-17.36 µM and 0.11-28.01 µM, respectively. As a result of nutrient enrichment, phytoplankton growth was very intensive, reflected by an abnormally high concentration of chlorophyll-a (annual average: 13.64±10.69 µg l −1 at surface and 3.96 ±2.42 µg l −1 at bottom water).

The regeneration of pore water (PW) nutrients was investigated and the contribution of benthic nutrient fluxes to the overlying bottom water (BW) was examined. Dissolved inorganic nutrients (

The fabrication of crosslinked polyaniline/Pterocladia capillacea-activated carbon composite (CrossPANI/P-AC) at different ratios (1:0, 1:0.2, 1:0.6, and 1:1) was studied. CrossPANI/P-AC composites were fabricated by the in situ polymerization of aniline using hydrogen chloride as an acidic dopant, and ammonium persulfate as initiator, while Pterocladia capillacea-activated carbon was synthesized by the chemical activation method and incorporated into the polymer matrix. The samples were characterized by the terms such as Fourier transform infrared (FTIR) spectroscopy, Brunauer–Emmett–Teller, X-ray diffraction (XRD), thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy (EDX). FTIR spectroscopy showed the main characteristic peak positions of CrossPANI/P-AC; XRD showed low crystallinity of CrossPANI/P-AC. A high specific surface area for CrossPANI/P-AC was achieved at a ratio of 1:0.2 where Brunauer–Emmett–Teller surface area, total pore volume, and mean pore diameter values were 166.10 m2/g, 0.0141 cm3/g, and 3.40 nm, respectively. The capability of CrossPANI/P-AC (1:0.2) composite as adsorbent for Direct blue-86 (DB-86) dye from aqueous solution was investigated. The impact of initial dye concentration, temperature, pH, and contact time on the DB-86 dye adsorption from its water solution was examined. The equilibrium adsorption data were well represented by the Langmuir isotherm achieving maximum monolayer capacity (Qm) of 163.93 mg/g at a dose of 0.5 g/L. In contrast, the kinetic adsorption data were well fit by the pseudo-second-order model. Thermodynamic analysis demonstrated that DB-86 dye adsorption occurs spontaneously, endothermically, and physically in nature. The results demonstrated that these composites effectively removed DB-86 dye from aqueous solutions and could be recycled. Graphical abstract

The effect of contact time and temperature on the formation of trihalomethanes (THMs) was studied during the chlorination of Khandaq El-Sharqi canal, Egypt, under laboratory condition. Samples were collected from four positions of Khandaq El-Sharqi canal (Itay El-Baroud, Dinshal, Damanhour and El-Zawya). Increasing trihalomethanes formation has been observed with increasing contact time and temperature. In the presence of excess chlorine, trihalomethanes formation proceeds as a pseudo-first-order reaction. The rate constants of the formation of trihalomethanes at different temperatures (10, 20, 30 and 40 °C) were calculated. Values of rate constant given for chloroform (CFM), bromodichloromethane (BDCM), dibromochloromethane (DBCM) and total trihalomethanes (TTHMs) approached each other, whereas chloroform attained a higher value for each temperature. Thermodynamic parameters of activation (ΔH # , ΔS # and ΔG #) for the formation of trihalomethanes were calculated by least square procedure program at 25 °C. The data showed that there is no significant change observed in ΔG # , and this is presumably due to the compensation between ΔH # and ΔS # to each other.

Binary orotic acid metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), and two mixed metals complexes of (Co(II), Ni(II)) and (Ni(II), Cu(II)) were synthesized and characterized by elemental analysis, IR, electronic spectra, magnetic susceptibility, and ESR spectra. The Analysis proved that the ligand has different coordination modes and the complexes were of octahedral, tetrahedral, and trigonal bipyramidal geometries. Molecular modeling techniques and quantum chemical methods have been performed for orotic acid to calculate charges, bond lengths, bond angles, dihedral angles, electronegativity (χ), chemical potential (µ), global hardness (η), softness (σ) and the electrophilicity index (ω). The thermal decomposition of the complexes was monitored by TGA, DTA, and DSC techniques under the N 2 atmosphere. The thermal decomposition mechanisms of the complexes were suggested. The biological activity of orotic acid and some of the complexes are tested against antibacterial and antifungal organisms.

Synthesis of new Fe(III), Co(II), Ni(II), and Cu(II) complexes of two azo ligands; 1-(phenyldiazenyl) naphthalene-2-ol (sudan orange R, HL1), and sodium 2-hydroxy-5-[(E)-(4-nitrophenyl) diazenyl]benzoate (alizarin yellow GG, HL2) have been reported. Stoichiometries of 1:2 and 1:3 (M:L) of the synthesized complexes were approved by total-reflection X-ray fluorescence technique (TXRF) and by elemental analyses. The geometry of complexes (octahedral and square planar) was typified by various spectroscopic, thermal, and magnetic techniques. The ESR spectroscopy showed that Cu(II) complexes are of different isotropic and rhombic symmetries with the existence of Cu–Cu ions interaction. TGA, DTA, and DSC analyses supported the multi-stage thermal decomposition mechanisms, where the thermal breakdown is ended by the formation of metal oxide in most cases. Moreover, chemical reactivity modeling using the density functional theory (DFT) method with the B3LYP/6–31 basis set, showed that metal complexes are more biologically active than their precursor ligands. The calculated lipophilicity character for metal complexes is in the range of 33.8–37.5 eV. Docking results revealed high scoring energy for [Fe(HL2)3].H2O complex and moderate inhibition strength of [Cu(L1)2].H2O complex versus 1bqb, 3t88, and 4esw proteins. Ultimately, the extent of biological effectiveness was endorsed experimentally against four microbial strains. The results are guidelines for toxicological investigations. Graphical Abstract