Iron removal from aqueous solutions by amphistegina filter

A semi-pilot filtration unit had been assembled to determine the potential and the effectiveness of the single-media filtration of amphistegina tests and granular activated carbon (GAC) filters in the removal of iron from aqueous solutions in a comparative study. The results revealed that the maximum adsorption capacities of Fe(II) by GAC and amphistegina filters at 313 K and higher flow rate (60 l/min) were 4.19 and 1.34 mg/g, while at lower flow rate (20 l/min) were 3.68 and 3.64 mg/g, respectively. Also, Freundlich and Langmuir adsorption isotherms were used to verify the adsorption performance and thermodynamic parameters were discussed.     

Cationic Mobility Via Cation-Exchange Mechanism on Poly(8-Hydroxyquinoline) Matrix

The insertion of Al(III) cation into a poly(8-Hydroxyquinoline) (PHQ) instead of some metal ions such as Co(II), Ni(II), Zn(II) or Fe(III) ions via cation-exchange mechanism has been studied by several techniques. The presence of Al(III) and the absence of Co(II) cations has been proved by elemental analysis of the polymer chelates product. Molecular mechanics (MM+) calculations showed that the potential energy (PE, kJ mol⁻¹) of the optimum molecular geometric structure (OMG) of the PHQ–Al(III) matrix is about seventy-six (76.185) greater than the PE of the PHQ–Co(II) complex. The TGA thermograms show that the PHQ–Al(III) matrix is thermally unstable than the PHQ–Co(II) complex under the same conditions. These observations indicate that the PHQ–Al(III) is expanded coil-like form. So, the thermal decomposition of PHQ–Al(III) complex is easy than the compacted coil-likes form of PHQ–Co(II) complex. The incorporation of Al(III) ion via cation-exchange properties have been investigated by spectrophotometric technique. The decrease of the absorbance at about ~370 nm of PHQ–Co(II) complex associated with increasing concentration of Al(III) revealed the replacement of that metal ion by Al(III) into PHQ chain. The cation-exchange constant (K _ex) of the divalent ions [Ni(II), Co(II), Cr(II), Zn(II), Mn(II), Mg(II) and Cu(II)] from PHQ–M(II) by the additions of Al(III) according to the following series: Ni(II) > Co(II) > Cr(II) > Cu(II) > Zn(II) > Mn(II) > Mg(II).     

Diclofenac-Bismuth Complex: Synthesis,Physicochemical, and Biological Evaluation

Diclofenac-bismuth complexation was attempted by mixing diclofenac sodium (Na) and bismuth-subcitrate aqueous solutions at diclofenac:bismuth molar ratio of 3:1. A solid precipitate was obtained and isolated. The precipitate was characterized for stoichiometric ratio of diclofenac-bismuth complexation using capillary electrophoresis, which showed 1:1 complexation. In addition, nuclear magnetic resonance and Fourier transform infrared analysis were performed for the isolated solid complex and indicated that bismuth was in coordinate bond formation with the carboxylate group of diclofenac. In comparison with diclofenac Na powder, the complex was evaluated as an aqueous suspension for in vitro drug dissolution. The complex exhibited a faster dissolution rate than and similar dissolution extent as diclofenac Na. In comparison with an aqueous solution of diclofenac Na and an aqueous suspension of physical mixture of diclofenac acid (suspended) and bismuth-subcitrate (dissolved), the aqueous complex suspension was evaluated for ulcerogenic effect in rats upon oral administration. The complex led to more gastric ulceration than diclofenac Na, which was not in accordance with the antiulcer properties of bismuth. This antiulcer effect was shown as the physical mixture administration was accompanied with lower gastric ulceration than diclofenac Na administration. These gastric ulceration results were explained in terms of the difference in particle size between solid diclofenac acid formed as a result of the complex breakdown in an acidic medium (0.1 M HCl to simulate the gastric fluid) and that formed as a result of diclofenac Na neutralization. Diclofenac acid particles formed from the complex breakdown were of average size, three times smaller of those formed as a result of diclofenac Na protonation. This difference in particle size was correlated with the higher gastric ulceration associated with the complex than with diclofenac Na in terms of higher coverage of the gastric mucosa with diclofenac, and consequently, higher local ulceration.     

Effect of singlet oxygen sensitizers and quenchers on the photo-oxidation of some unsaturated polymers

The photo-oxidation of cis-polyisoprene was studied in the absence and in the presence of both singlet oxygen sensitizers (benzophenone, anthracene, rubrene) and quenchers (benzidine, diphenylamine, β-carotene). The amount of hydroperoxide which was formed at constant flow rate of oxygen during the u.v. irradiation of cis-polyisoprene increased by increasing the concentration of sensitizer as well as the number of quanta absorbed. The efficiency of the sensitizers used for the formation of hydroperoxide increased in the order: benzophenone < anthracene < rubrene. This effect was attributed to the fact that anthracene and rubrene can sensitize the photo-oxidation reaction by both physical and chemical generation of singlet oxygen while the generation of singlet oxygen is a purely physical process in case of benzophenone. In presence of quencher compounds β-carotene was more efficient than diphenylamine and the latter was more efficient than benzidine. The effect of a singlet oxygen oxidation on the different organic polymers was in the sequence: cis-polyisoprene > polybutadiene > styrene-polybutadiene > polychloroprene.     

Novel combination of anionic and cationic polymethacrylate polymers for sustained release tablet preparation

The objectives of this study were to prepare and evaluate a novel sustained release tablet formulation using a binary mixture of polymethacrylate polymers: Eudragit E-100 (EE) and Eudragit L-100 (EL) in their salt forms. Tablets prepared using EE-citrate and EL-Na showed the highest degree of swelling among other combinations of EE and EL. The drug release rates were independent of the pH of the dissolution medium as the release profiles exhibited a continuous release pattern with no burst effect when changing the pH of the medium. These results, along with other test results, indicated the presence of an ionic interaction between both polymers when combined in the salt forms.     

Novel Surface Topography and Microhardness Characterization of Laser Clad Layer on TC4 Titanium Alloy Using Laser-Induced Breakdown Spectroscopy and Machine Learning

Metallurgical and Materials Transactions A - This study was performed to characterize surface topography and microhardness of 40 wt pct NiCrBSiC-60 wt pct WC hard coating on TC4 titanium after...