Synthesis and characterization of nano-composite ion-exchanger; its adsorption behavior

A novel organic-inorganic nanocomposite cation-exchanger has been synthesized via sol-gel method. It was characterized on the basis of FTIR, XRD, SEM, TEM, AFM and Raman studies. The structural studies reveal semi-crystalline nature of the material with the particle size ranging from 1-5 nm. Physiochemical properties such as ion-exchange capacity, chemical and thermal stability of composite material have also been determined. Bifunctional behavior of the material has been indicated by its pH titrations curves. The nanocomposite material exhibits improved thermal stability, higher ion-exchange capacity and better selectivity for toxic heavy metals. The ion-exchange material shows an ion-exchange capacity of 1.8 meq g(-1) for Na(+) ions. Sorption behavior of metal ions on the material was studied in different solvents. The cation exchanger was found to be selective for Pb(II), Hg(II) and Zr(IV) ions. The limit of detection (LOD) and the limit of quantification (LOQ) for Pb(II) ion was found to be 0.85 and 2.85 μg L(-1). Analytically important separations of heavy metal ions in synthetic mixtures as well as industrial effluents and natural water were achieved with the exchanger. The practical utility of polyanilineZr(IV)sulphosalicylate cation exchanger has been established for the analysis and recovery of heavy metal ions in environmental samples.     

Aerobic photocatalytic oxidation of activated benzylic and allylic alcohols to carbonyl compounds catalyzed by molecular iodine

An efficient, selective and environmentally benign photocatalytic system in acetonitrile has been developed for aerobic oxidation of activated benzylic and allylic alcohols into their corresponding aldehydes and ketones without the need for a transition metal in moderate to excellent yields with a catalytic amount of iodine. Very high inter- and intramolecular chemoselectivities are observed when benzylic OH groups are oxidized in the presence of aliphatic (nonbenzylic) hydroxyls.     

Analysis of testosterone in human urine using molecularly imprinted solid-phase extraction and corona discharge ion mobility spectrometry

Analysis of testosterone was accomplished using corona discharge ion mobility spectrometry. Molecular imprinted polymer was used for the extraction and pre-concentration of testosterone. Analytical parameters including precision, dynamic range and detection limit were obtained. The linear dynamic range was from 10 to 250 ng/mL and the limit of detection was 0.9 ng/mL. The proposed method was used for analysis of testosterone in urine samples. A urine sample from a 3-year-old girl was used as the blank. The RSD was below 10%. The obtained results from the method were also compared with the standard method for analysis of testosterone using SPE-HPLC analysis. The results demonstrate the accuracy of the method.     

Synthesis, characterisation, reactivity and in vitro antiamoebic activity of hydrazone based oxovanadium(IV), oxovanadium(V) and mu-bis(oxo)bis{oxovanadium(V)} complexes

Binuclear, mu-bis(oxo)bis{oxovanadium(V)} complexes [(VOL)2(mu-O)2](2 and 7)(where HL are the hydrazones Hacpy-nah I or Hacpy-fah II; acpy = 2-acetylpyridine, nah = nicotinic acid hydrazide and fah = 2-furoic acid hydrazide) were prepared by the reaction of [VO(acac)2] and the ligands in methanol followed by aerial oxidation. The paramagnetic intermediate complexes [VO(acac)(acpy-nah)](1) and [VO(acac)(acpy-fah)](6) have also been isolated. Treatment of [VO(acac)(acpy-nah)] and [VO(acac)(acpy-fah)] with aqueous H2O2 yields the oxoperoxovanadium(V) complexes [VO(O2)(acpy-nah)](3) and [VO(O2)(acpy-fah)](8). In the presence of catechol (H2cat) or benzohydroxamic acid (H2bha), 1 and 6 give the mixed chelate complexes [VO(cat)L](HL =I: 4, HL =II: 9) or [VO(bha)L](HL =I: 5, HL =II: 10). Complexes 4, 5, 9 and 10 slowly convert to the corresponding oxo-mu-oxo species 2 and 7 in DMF solution. Ascorbic acid enhances this conversion under aerobic conditions, possibly through reduction of these complexes with concomitant removal of coordinated catecholate or benzohydroxamate. Acidification of 7 with HCl dissolved in methanol afforded a hydroxo(oxo) complex. The crystal and molecular structure of 2.1.5H2O has been determined, and the structure of 7 re-determined, by single crystal X-ray diffraction. Both of these binuclear complexes contain the uncommon asymmetrical {VO(mu-O)}2 diamond core. The in vitro tests of the antiamoebic activity of ligands I and II and their binuclear complexes 2 and 7 against the protozoan parasite Entamoeba histolytica show that the ligands have no amoebicidal activity while their vanadium complexes 2 and 7 display more effective amoebicidal activity than the most commonly used drug metronidazole (IC50 values are 1.68 and 0.45 microM, respectively vs 1.81 microM for metronidazole). Complexes 2 and 7 catalyse the oxidation of styrene and ethyl benzene effectively. Oxidation of styrene, using H2O2 as an oxidant, gives styrene epoxide, 2-phenylacetaldehyde, benzaldehyde, benzoic acid and 1-phenyl-ethane-1,2-diol, while ethyl benzene yields benzyl alcohol, benzaldehyde and 1-phenyl-ethane-1,2-diol.     

Immunogenic Potential and Therapeutic Efficacy of Multi-Epitope Encapsulated Silk Fibroin Nanoparticles against Pseudomonas aeruginosa-Mediated Urinary Tract Infections

Pseudomonas aeruginosa (P. aeruginosa) causing urinary tract infections (UTIs) are a major concern among hospital-acquired infections. The need for an effective vaccine that reduces the infections is imperative. This study aims to evaluate the efficacy of a multi-epitope vaccine encapsulated in silk fibroin nanoparticles (SFNPs) against P. aeruginosa-mediated UTIs. A multi-epitope is constructed from nine proteins of P. aeruginosa using immunoinformatic analysis, expressed, and purified in BL21 (DE3) cells. The encapsulation efficiency of the multi-epitope in SFNPs is 85% with a mean particle size of 130 nm and 24% of the encapsulated antigen is released after 35 days. The vaccine formulations adjuvanted with SFNPs or alum significantly improve systemic and mucosal humoral responses and the cytokine profile (IFN-γ, IL-4, and IL-17) in mice. Additionally, the longevity of the IgG response is maintained for at least 110 days in a steady state. In a bladder challenge, mice treated with the multi-epitope admixed with alum or encapsulated in SFNPs demonstrate significant protection of the bladder and kidneys against P. aeruginosa. This study highlights the promising therapeutic potential of a multi-epitope vaccine encapsulated in SFNPs or adjuvanted with alum against P. aeruginosa infections.     

Separation and preconcentration of Ag(I) in aqueous samples by flotation as an ion-associate using iodide and ferroin followed the determination by flame atomic absorption spectrometry

A simple method for separation/preconcentration and determination of Ag(I) in aqueous samples is described. The method is based on formation of an ion-associate between Ag(I)-iodide complex and ferroin, which can be floated at the interface of the aqueous/n-heptane phases. The flotation process was carried out using 500-ml aliquot of the aqueous solution and the floated layer was dissolved in 5 ml of 1 M HNO3 containing methanol (50% v/v) as the solvent. The Ag(I) content was then determined by flame atomic absorption spectrometry (FAAS). The method so could be considered as an enrichment process, was achieved to a quantitative feature, when the pH of the solution was adjusted to 4 and the concentrations of iodide and ferroin were about 3.2 x 10(-4) M and 6.25 x 10(-5) M, respectively. The LOD and RSD (n = 7) were obtained 1.0 x 10(-8) M and 2.4%, respectively. It was found that a large number of cations and anions even at high considerably foreign ion/Ag(I) ratios were not interfered. The method was applied satisfactorily to recovery of Ag(I) from different aqueous samples.     

Sensitized extraction spectrophotometric determination of Hg(II) with dithizone after its flotation as ion-associate using iodide and ferroin

This paper describes a simple and highly selective method for the separation, preconcentration and spectrophotometric determination of extremely low concentration of mercury. The method is based on the flotation of an ion-associate of HgI₄²⁻ and ferroin between aqueous and n-heptane interface at pH 5. The ion-associate was then separated and treated with ammonia and dithizone solutions to extract only the mercury chelate with CH₂Cl₂. The measurement is feasible when the volume of the water sample containing Hg(II) was varied over 50-800 ml. Beer's law was obeyed over the concentration range of 8 × 10⁻⁹ to 1.6 × 10⁻⁷ mol l⁻¹ with an apparent molar absorptivity of 6.53 × 10⁶ l mol⁻¹ cm⁻¹ for a 500 ml aliquot of the water sample. The detection limit (n = 7) was 5.0 × 10⁻¹⁰ mol l⁻¹ and the R.S.D. (n = 5) for 8.0 × 10⁻⁷ mol l⁻¹ of Hg(II) was 3.7%. A notable advantage of the method is that the determination of Hg(II) is free from the interference of almost all cations and anions found in the environmental and waste water samples. The determination of Hg(II) in tap, synthetic sea water and human hair samples was carried out by the present method and cold vapor atomic absorption spectrometry (CV-AAS). The results were satisfactorily comparable so that the applicability of the proposed method was confirmed to the real samples.     

A combined CFD modeling with population balance equation to predict pressure drop in venturi scrubbers

A venturi scrubber is one of the most important devices for air pollution control. Although there are different models for predicting the pressure drop in venturi scrubbers, most of them have some defects and cannot predict the pressure drop correctly. In this study, for the first time, an Eulerian–Eulerian computational fluid dynamics (CFD) model is combined with a population balance equation to predict the pressure drop in venturi scrubbers. This simulation takes into account a multiple size group model for droplet dispersion and droplet size distribution, which is based on a population balance equation. Flow field has been calculated by solving the time averaged continuity and Navier–Stokes equations along with the standard k–ε turbulence model. The equations included drag, turbulent dispersion, and buoyancy forces. The calculated pressure drop with and without considering the population balance equation was compared with the experimental data to evaluate the accuracy of the CFD modeling. The size distribution of droplets in the venturi scrubber was studied at different points for different liquid to gas ratios and throat gas velocities. The results show that the maximum break-up of droplets happens at the liquid injection point. Finally, the effects of nozzle diameter and nozzle arrangement on pressure drop in venturi scrubbers were investigated.     

Effect of ceria and zirconia nanoparticles on mechanical behavior of nanocomposite hybrid coatings

Epoxy-silica based hybrid nanocomposite coatings have been developed with different organicinorganic contents by sol–gel process. Various ratios of ceria and zirconia colloidal dispersions as inorganic nanoparticles are uniformly distributed in the hybrid sol. The hybrid sols are prepared by hydrolysis and condensation of 3-glycidoxypropyltrimethoxysilane (GPTMS) and tetraethylorthosilicate (TEOS) in acidic solution using bisphenol A (BPA) and 1-methyl-imidazol (MI). A thin layer of each sol is coated on a micro-glass slide and 1050 aluminum alloy as substrates. The effect of alkoxysilane precursors (i.e. TEOS and GPTMS) and inorganic to organic molar ratio are investigated. Nanoindentation and dynamic mechanical analysis (DMA) performed to characterize the mechanical properties of the coatings in nanorange scale. It is revealed that all hybrid nanocomposite coatings had appropriate flexibility and strong interfacial interaction with the aluminum alloy substrate. It is proposed that the ceria and zirconia nanoparticles can be bonded to the surrounding of siloxane ring which can be induced high restriction in polymeric chain mobility in dynamic mechanical analysis. Nanoindentation tests showed that by increasing the inorganic phase in the nanocomposite, both elastic modulus and hardness increase, especially they are very intense in the higher levels of inorganic content.