Synthesis and Characterization of Magnetically Retrievable Fe3O4/Polyvinylpyrrolidone/Polystyrene Nanocomposite Catalyst for Efficient Catalytic Oxidation Degradation of Dyes Pollutants

Recently, the application of metal oxides such as Fe₃O₄ nanoparticles have wide interest for environmental remediation and treatment of wastewater especially contaminated with azo dyes owing to its high degradation efficacy and low toxicity. The recovery of magnetic catalysts without losing their efficiency is an essential feature in the catalytic applications. The aim of this article is to investigate and synthesis of magnetically retrievable Fe₃O₄/polyvinylpyrrolidone/polystyrene (Fe₃O₄/PVP/PS) nanocomposite for the catalytic degradation of azo dye acid red 18 (AR18). Fe₃O₄/PVP/PS nanocomposite was prepared in two steps. Firstly, PVP/PS microsphere was synthesized by γ-irradiation polymerization of styrene in presence of PVP solution. Secondly, deposition of Fe₃O₄ nanoparticles on PVP/PS microsphere was achieved by the alkaline co-precipitation of Fe³⁺/Fe²⁺ ions. The chemical structural and morphological properties of PVP/PS microsphere and Fe₃O₄/PVP/PS nanocomposite were examined by XRD, TEM, DLS, FTIR, EDX and VSM techniques. TEM results showed homogeneous morphology, spherical shaped and well-dispersed Fe₃O₄ nanoparticles with average particle size of 26 nm around PVP/PS microspheres. The VSM measurements of Fe₃O₄/PVP/PS nanocomposite exhibit excellent magnetic response of saturation magnetization 26.38 emu/g which is suitable in magnetic separation. The effect of the synthesized Fe₃O₄/PVP/PS nanocomposite on the catalytic degradation of AR18 in presence of hydrogen peroxide (H₂O₂) as a heterogeneous Fenton-like catalyst was examined. The catalyst Fe₃O₄/PVP/PS/H₂O₂ played basic role in promoting the oxidation degradation efficiency of AR18 of initial concentration 50 mg/L to 94.4% in 45 min with excellent recyclability till the sixth cycles under the best conditions of pH 3, 2% v/v H₂O₂ and 0.3 g catalyst amount. Furthermore, the Fe₃O₄/PVP/PS/H₂O₂ hybrid catalyst system supports high capability for oxidation degradation of mixture of different dyes. The Fe₃O₄/PVP/PS nanocomposite catalyst had high magnetic and recyclability characters which are acceptable for the treatment of wastewater contaminated by various dyes pollutants.

     

Magnetic 99mTc- core-shell of polyethylene glycol/polyhydroxyethyl methacrylate based on Fe3O4 nanoparticles: Radiation synthesis,characterization and biodistribution study in tumor bearing mice

Magnetic nanoparticles (Fe₃O₄) coated with polyethylene glycol (PEG), (Fe₃O₄/PEG), were synthesized by chemical co-precipitation of Fe²⁺/Fe³⁺ salts by aqueous ammonia in PEG solution. Radiation polymerization of 2-hydroxyethyl methacrylate (HEMA) monomer solution onto Fe₃O₄/PEG was performed at different doses to synthesize (Fe₃O₄/PEG)-pHEMA, namely FPH, nanocomposites. Properties of FPH nanocomposites were characterized by FT-IR, XRD, SEM, TEM, DLS, ESR and TGA techniques. The XRD of FPH nanocomposites showed all the peaks of Fe₃O₄ nanoparticles. SEM was used to assess the surface morphology of FPH. TEM showed that the average diameter of FPH nanocomposites was in the range of 9–40 nm. The thermal stability of FPH nanocomposites was higher than that of Fe₃O₄ and Fe₃O₄/PEG. Radio-labeling of (Fe₃O₄/PEG)-pHEMA nanocomposite irradiated at 10 kGy (FPH10) with ^99mTc was performed using stannous chloride as reducing agent. Factors affecting the labeling yield (%) such as the substrate amount, the amount of reducing agent, the pH of reaction medium, the reaction time and the reaction temperature were investigated. The maximum labeling yield was 93% using 0.25 mg of FPH10 at pH 6 and 20 min reaction time. The biodistribution study of ^99mTc-FPH10 was examined on two groups of ascites and solid tumor bearing mice. The biodistribution results referred that ^99mTc-FPH10 was rapidly uptake in tumor sites ascites or solid tumors. The results indicated that FPH nanocomposites could be potentially used for tumor imaging and therapy.     

Variations in some heavy metals’ level during processing of soft cheese

The aim of this study was to determine the content of lead, cadmium, aluminum, copper and mercury during Feta cheese manufacturing by using atomic absorption spectrometer. Results revealed that lead and mercury concentrations were higher after curdling and in fresh cheese after salting than other elements. Cadmium was detected at low concentrations in raw milk, pasteurized milk, after curdling and fresh cheese (0.053, 0.10, 0.20 and 0.24 mg/kg, respectively). Aluminum concentration did not change seriously during different steps of cheese manufacturing. On the other hand, the concentration of copper increased from 2.83 ± 0.97 mg/kg in raw milk to 3.25 ± 1.06 mg/kg in fresh cheese. It was concluded that the curdling and cheese after salting are the major technological steps that affect the concentration of some heavy metals rather than heat treatment.     

Flow and heat transfer of a micropolar fluid in an axisymmetric stagnation flow on a cylinder with variable properties and suction (numerical study)

Summary. In this paper, an analysis is presented to study the effects of variable properties, density, viscosity and thermal conductivity of a micropolar fluid flow and heat transfer in an axisymmetric stagnation flow on a horizontal cylinder with suction, numerically. The fluid density and the thermal conductivity are assumed to vary linearly with temperature. However, the fluid viscosity is assumed to vary as a reciprocal of a linear function of temperature. The similarity solution is used to transform the problem under consideration into a boundary value problem of nonlinear coupled ordinary differential equations which are solved numerically by using the Chebyshev finite difference method (ChFD). Numerical results are carried out for various values of the dimensionless parameters of the problem. The numerical results show variable density, variable viscosity, variable thermal conductivity and micropolar parameters, which have significant influences on the azimuthal and the angular velocities and temperature profiles, shear stress, couple stress and the Nusselt number. The numerical results have demonstrated that with increasing temperature ratio parameter the azimuthal velocity decreases. With increasing variable viscosity parameter the temperature increases, whereas the azimuthal and the angular velocities decrease. Also, the azimuthal and the angular velocities increase and the temperature decreases as the variable conductivity parameter increases. Finally, the pressure increases as the suction parameter increases.     

Radiation Synthesis and Characterization of Poly (vinyl alcohol)/acrylamide/TiO2/SiO2 Nanocomposite for Removal of Metal Ion and Dye from Wastewater

PVA-co-AAm/TiO₂/SiO₂ nanocomposites adsorbents synthesized by γ-irradiation copolymerization of polyvinyl alcohol (PVA) and acrylamide (AAm) incorporated TiO₂/SiO₂ nanopowders, aiming to enhance the removal of basic blue 3 dye (BB3) and Cu (II) ions from aqueous solutions. Properties of nanocomposites were analyzed by different techniques. FTIR results showed successful incorporation of nanoparticles and copolymerization of PVA and AAM. SEM/EDS confirm the peaks belonging to C, O, Si, and Ti. TEM investigation illustrated that TiO₂/SiO₂ nanoparticles were well dispersion, uniform, and homogeneous shape of particle size of 60–70 nm. XRD data specified characteristic diffraction peaks of TiO₂ and the calculated crystalline size was 43 nm. Adsorption results confirm that PVA-co-AAm/TiO₂/SiO₂ nanocomposites provide better adsorption capacities of both BB3 and Cu (II) was three-folds rather than PVA-co-AAm-30. The nanocomposite prepared at 30 kGy (PVA-co-AAm/TiO₂/SiO₂-30) showed high swelling, gelation, and highest adsorption capacity and it was selected as the best adsorbent for batch experiments. The optimum adsorption was achieved using 0.4 g PVA-co-AAm/TiO₂/SiO₂-30 adsorbent dosage. The adsorption capacity of BB3 and Cu (II) was 140.9 and 190.3 mg/g with a removal efficiency of 93.5 and 95.2% after 7 h and 6 h, pH 11 and pH 6, and initial concentration of 150 and 200 mg/L, respectively. The adsorption of BB3 or Cu (II) was endothermic and spontaneous, well described by the pseudo-second-order adsorption kinetic and fit Langmuir isotherm. The results revealed that the as-synthesized PVA-co-AAm/TiO₂/SiO₂ nanocomposites could be employed as effective adsorbents for the adsorption of BB3 and Cu (II) ions from wastewater with high adsorption capacity and recovery.

     

Antibacterial and anticancer activity of loaded quinazolinone polypyrrole/chitosan silver chloride nanocomposite

Polypyrrole/chitosan-silver chloride core shell nanocomposite (AgCl@PPC) was prepared by in situ oxidative polymerization of pyrrole (Py) using ferric chloride in the presence of chitosan (CS) and silver nitrate to develop a carrier and controlled release system for 3-amino-2-phenyl-4(3H)-quinazolinone (I). For sake of comparison, polypyrrole chitosan core shell nanoparticles (PPC) were prepared and loaded by (I). Fourier transform infrared spectroscopy, X-ray diffraction and thermal gravimetric analysis confirm that I was loaded into PPC and AgCl@PPC core shell nanocomposites respectively, through physical interaction. Results revealed that loaded AgCl@PPC and PPC exhibited excellent antibacterial and anticancer efficacy against Ehrlich ascites carcinoma cells.     

Polyamide‐montmorillonite nanocomposites as a drug delivery system: Preparation,release of 1,3,4‐oxa(thia)diazoles,and antimicrobial activity

New microbicidal polyamides were prepared by the reaction of 5‐phenyl‐1,3,4,‐oxadiazole‐2‐thiol, 5‐phenyl‐1,3,4‐oxadiazole‐2‐amine, and 5‐(4‐chlorophenyl)?1,3,4‐thiadiazole‐2‐thiol with ethyl chloroformate followed by polycondensation with polyoxypropylenetriamine (Jeffamine T₄₀₃). The polyamides were modified to yield amine hydrochloride. The intercalation of polyamides into montmorillonite (MMT) was achieved through an ion exchange process between sodium cations in MMT and amine hydrochloride in the polyamides. The structure of the resulting materials was characterized with elemental analysis, proton nuclear magnetic resonance, Fourier transform infrared‐spectroscopy, X‐ray diffraction, thermogravimetric analysis, and transmission electron microscope. The release behavior of 1,3,4‐oxa(thia)diazoles was investigated in buffered aqueous solution at different pH values (2.3, 5.8, and 7.4). A slow release was recorded from the nanocomposites whereas; the release reaches almost 90% from polyamides. The in vitro antimicrobial activity of the polyamides and nanocomposites was studied against Gram‐negative bacteria, Gram‐positive bacteria, Yeast and the filamentous fungi by well diffusion method. The polymers showed good or moderate antimicrobial activities. However, nanocomposites showed no antimicrobial effect. Furthermore, in vivo study showed that nanocomposites had good antimicrobial activity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41177.     

Antioxidative properties of irradiated chitosan/vitamin C complex and their use as food additive for lipid storage

Improving the antioxidant activity of chitosan was achieved by decreasing their molecular weight by γ rays followed by incorporation with vitamin C to prepare chitosan/vitamin C (CSVC) complex in the range of nanoparticles. Transmittance electron microscopy of CSVC complex showed mean diameters ranged from 23.2 to 82 nm. The antioxidant activities of CSVC complexes were examined using scavenging effect on DPPH radicals and reducing power measurements. CSVC complexes have a synergistic effect on increasing the antioxidant properties rather than their individual effects. The effect of CSVC complexes on lipid peroxidation of meat during 21 days of refrigerated storage was investigated using thiobarbituric acid reactive substance (TBARS) assay. Treatment of meat with CSVC complex reduced lipid peroxidation about 75% after 7 days of storage as a result the decrease in TBARS values. The results demonstrate promising use of CSVC complex as antioxidants for lipid storage. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42105.     

Efficient Chebyshev–Petrov–Galerkin Method for Solving Second-Order Equations

A new efficient Chebyshev–Petrov–Galerkin (CPG) direct solver is presented for the second order elliptic problems in square domain where the Dirichlet and Neumann boundary conditions are considered. The CPG method is based on the orthogonality property of the kth-derivative of the Chebyshev polynomials. The algorithm differs from other spectral solvers by the high sparsity of the coefficient matrices: the stiffness and mass matrices are reduced to special banded matrices with two and four nonzero diagonals respectively. The efficiency and the spectral accuracy of CPG method have been validated.     

Novel antibacterial lactoferrin peptides generated by rennet digestion and autofocusing technique

Bovine lactoferrin was hydrolysed with a range of proteolytic enzymes including calf rennet, fungal rennin, and porcine pepsin. Lactoferrin hydrolysates were assessed for their antibacterial activities against Escherichia coli and Bacillus subtilis. At pH 3, calf rennet lactoferrin hydrolysate before (LFH) showed the highest antimicrobial activity, then pepsin LFH, while fungal rennin LFH was the least active. The calf rennet and pepsin LFH were fractionated using autofocusing and chromatographic techniques. The activity-guided fractionation of calf rennet LFH identified a potent antimicrobial peptide of 11-residues, lactoferricin B (Lf-cin B), and three other novel antibacterial peptides. The 11-residues Lf-cin B was the most potent antibacterial peptide and was isolated from both rennet and pepsin LFH. Pepsin LFH had a main antimicrobial peptide of 25-residues, which was not detected in calf rennet LFH. It could be concluded that calf rennet LFH had stronger antibacterial properties than porcine pepsin LFH. Besides, autofocusing could be used for scaling up the isolation of the potent rennet LFH peptides that would have a widespread commercial use as a natural food preservative substituting porcine pepsin digest, especially in Islamic communities.