Adsorption of Cd(II) Ions onto Activated Carbon Prepared from Hazelnut Husks

In this study, a batch adsorption of Cd(II) ions onto activated carbon (AC) produced from hazelnut husks were investigated. The factors controlling the adsorption process such as initial pH, agitation time, dosage and initial concentration have been examined. The AC was showed a high affinity to Cd(II) ions at pH values between 5.0 and 7.0. The equilibrium time was found to be 300 minutes. Cd(II) adsorption equilibrium was analyzed with both Langmuir and Freundlich isotherm equations and it was found that Langmuir equations fitted well with the experimental data. Maximum Cd(II) adsorption capacity of AC was calculated to be 20.9 mg g^?1. Cd(II) adsorption kinetics described well with the pseudo second order model. The activated carbon prepared from hazelnut husks is efficient sorbent material for the removal of Cd(II) ions from aqueous solutions.     

Inorganic arsenic speciation in various water samples with GFAAS using coprecipitation

A simple, economic and sensitive method for selective determination of As(III) and As(V) in water samples is described. The method is based on selective coprecipitation of As(III) with Ce(IV) hydroxide in presence of an ammonia/ammonium buffer at pH 9. The coprecipitant was collected on a 0.45 µm membrane filter, dissolved with 0.5 mL of conc. nitric acid and the solution was completed to 2 or 5 mL with distilled water. As(III) in the final solutions was determined by graphite furnace atomic absorption spectrometry (GFAAS). Under the working condition, As(V) was not coprecipitated. Total inorganic arsenic was determined after the reduction of As(V) to As(III) with NaI. The concentration of As(V) was calculated by the difference of the concentrations obtained by the above determinations. Both the determination of arsenic with GF-AAS in presence of cerium and the coprecipitation of arsenic with Ce(IV) hydroxide were optimised. The suitability of the method for determining inorganic arsenic species was checked by analysis of water samples spiked with 4–20 µg L^?1 each of As(III) and As(V). The preconcentration factor was found to be 75 with quantitative recovery (≥95%). The accuracy of the present method was controlled with a reference method based on TXRF. The relative error was under 5%. The relative standard deviations for the replicate analysis ( n?=?5) ranged from 4.3 to 8.0% for both As(III) and As(V) in the water samples. The limit of detection (3σ) for both As (III) and As(V) were 0.05 µg L^?1. The proposed method produced satisfactory results for the analysis of inorganic arsenic species in drinking water, wastewater and hot spring water samples.     

Synthesis and Characterization of New Chelating Resin: Adsorption Study of Copper(II) and Chromium (III) Ions

Acrylamide based monomer, 5-methyl-2-thiozyl methacrylamide (MTMAAm) was synthesized by the reaction of 2-Amino-5-methyl thiazole with methacryloyl chloride in the presence of triethylamine(NR₃) at 0–5°C. The monomer MTMAAm was characterized by FT-IR and ¹H-and ¹³C-NMR spectral studies. A new chelating resin, poly(5-methyl-2-thiozyl methacrylamide-co-2-acrylamido-2-methyl-1-propanesulfonic acid-co-divinylbenzene) [MTMAAm/AMPS/DVB] was synthesized. This resin was characterized by FT-IR. In order to determine the adsorption behavior of chelating resin, the adsorption isotherm of Cr(III) and Cu(II) were studied. It was found that the adsorption isotherm of the ions fitted with Langmuir-type isotherms. From the Langmuir equation, the adsorption capacity of chelating resin for Cr(III) and Cu(II) was found to be 7.77 mg g^{? 1} and 4.27 mg g^{? 1}, respectively. Binding equilibrium constant was calculated to be 0.155 L mg^{? 1} and 0.106 L mg^{? 1} for Cu(II) and Cr(III), respectively.     

Design and Development of Oral Oil-in-Water Nanoemulsion Formulation Bearing Atorvastatin: In Vitro Assessment

The objective of the present investigation was to design a thermodynamically stable and dilutable nanoemulsion formulation of AT-Ca with minimum surfactant concentration that could improve its solubility as well as its oral bioavailability. The composition of optimized nanoemulsion formulation was Sefsol 218 and oleic acid (1:1) 10% w/w, as an oil phase, Tween-20 (19% w/w) as a surfactant, Carbitol (19% w/w) as a cosurfactant and distilled water (52% w/w) as an aqueous phase, containing 10 mg of AT. The optimized formulation showed higher% drug release (99.34%), lower droplet size (42.8 ± 0.42 nm) with low polydispersity index (0.237 ± 0.012), less viscosity (27.51 ± 1.01 cP) and infinite dilution capability. In vitro drug release from the nanoemulsion formulations was highly significant (p < 0.01) as compared to drug suspension.     

Synthesis,Characterization and Electrorheological Properties of Polyindene/Kaolinite Composites

In this study, synthesis, characterization and electrorheological (ER) properties of polyindene (PIN) and polyindene/kaolinite composites were carried out by cationic radical polymerization using FeCl₃ as the oxidizing agent. The homopolymer and composites, containing different amounts of PIN were characterized by FTIR spectroscopy, thermo‐gravimetric (TGA) analyses, scanning electron microscopy (SEM) and dynamic light scattering (DLS) methods. The conductivity and dielectric properties of PIN and PIN/kaolinite composites were determined. Suspensions of PIN and PIN/kaolinite composites were prepared in silicone oil (SO), at a series of concentrations (c=5–25 m/m %). The effects of concentration, shear rate, electric field strength, frequency, temperature and promoter on ER activities of suspensions were investigated.     

Four-Component,One-Pot Synthesis of 2-Aryl-4-Thionylquinoline Derivatives and Their Aromatization

Four-component, one-pot condensation of dimedon, thiophene-2-carbaldehyde, ammonium acetate, and numerous acetophenones yielded novel 2-aryl-4-thionylquinoline derivatives. The structures were characterized by ¹H NMR, ¹³C NMR, IR, and elemental analysis.     

Probing the Selectivity of Azomethine Imine Cycloaddition to Single‐Walled Carbon Nanotubes by Resonance Raman Spectroscopy

Selective covalent surface modification of single‐walled carbon nanotubes (SWNTs) is of great importance to various carbon nanotube‐based applications as it might offer an alternative method for enriching metallic and semiconducting nanotubes. Herein, we report on the surface modification of SWNTs through 1,3‐dipolar cycloaddition of 3‐phenyl‐phthalazinium‐1‐olate, which is a stable and reactive azomethine imine. For this reaction, microwave heating was found to be more efficient than conventional and solvent‐free heating. The sensitivity of cycloaddition to the molecular structure of SWNTs was probed using resonance Raman spectroscopy with three different laser excitations. Based on the obtained results, azomethine imine addition to the surface of nanotubes is selective for metallic and large‐diameter semiconducting SWNTs. Thermogravimetric analysis coupled with mass spectrometry showed that fragments released at high temperatures corresponded to the phenylphthalazine group, thus confirming the covalent surface functionalization. Modified SWNTs were further characterized by X‐ray photoelectron and UV/Vis‐NIR spectroscopies.     

A facile preparation of donut-like supramolecular tannic acid-Fe(III) composite as biomaterials with magnetic,conductive, and antioxidant properties

Tannic acid (TA) complexes with various metal ions are prepared in buffer solutions by readily adjusting the pH, but there is no normalizing method to produce ferric tannate complexes. In this study, TA-Fe(III) complex was prepared in reverse microemulsion medium by reaction of TA as ligand with Fe(III) in 1:3 ligand:metal ion molar ratio. The complex was characterized by SEM, AFM, FT-IR, elemental analysis, AAS measurement, and Brunauer-Emmett-Teller (BET) method. Furthermore, magnetic susceptibility was tested with the Gouy method, and electronic spectral studies of TA-Fe(III) complex were completed with solid UV–vis measurements. The thermal stability was also studied by TGA analysis. These studies show that the ligand molecules have octahedral arrangement around Fe(III) and the complex is paramagnetic. The bandgap energy of the complex was calculated as 3.42 eV with solid UV–vis analysis. To determine antioxidant activity of the complex, Total Phenol Content (TPC) and Trolox Equivalent Antioxidant Concentration (TEAC) methods were used. The complex has great antioxidant properties with TPC = 45 ± 1 mg L^?1 GAE and TEAC = 296 ± 2 mM trolox g^?1 for dry sample.     

Robust Inclusion Complexes of Crown Ether Fused Tetrathiafulvalenes with Li+@C60 to Afford Efficient Photodriven Charge Separation

Inclusion complexes of benzo‐ and dithiabenzo‐crown ether functionalized monopyrrolotetrathiafulvalene (MPTTF) molecules were formed with Li⁺@C₆₀ ( 1? Li⁺@C₆₀ and 2? Li⁺@C₆₀). The strong complexation has been quantified by high binding constants that exceed 10⁶ M ^?1 obtained by UV/Vis titrations in benzonitrile (PhCN) at room temperature. On the basis of DFT studies at the B3LYP/6‐311G(d,p) level, the orbital interactions between the crown ether moieties and the π surface of the fullerene together with the endohedral Li⁺ have a crucial role in robust complex formation. Interestingly, complexation of Li⁺@C₆₀ with crown ethers accelerates the intersystem crossing upon photoexcitation of the complex, thereby yielding ³(Li⁺@C₆₀)*, when no charge separation by means of ¹Li⁺@C₆₀* occurs. Photoinduced charge separation by means of ³Li⁺@C₆₀* with lifetimes of 135 and 120 μs for 1? Li⁺@C₆₀ and 2? Li⁺@C₆₀, respectively, and quantum yields of 0.82 in PhCN have been observed by utilizing time‐resolved transient absorption spectroscopy and then confirmed by electron paramagnetic resonance measurements at 4 K. The difference in crown ether structures affects the binding constant and the rates of photoinduced electron‐transfer events in the corresponding complex.     

Preconcentration and separation of copper(II), cadmium(II) and chromium(III) in a syringe filled with 3-aminopropyltriethoxysilane supported on silica gel

In this study, a syringe was filled with silica gel loaded with 3-aminopropyltriethoxysilane, for the separation and preconcentration of copper, cadmium and chromium prior to their determination by graphite furnace atomic absorption spectrometry (GFAAS) in seawater. For this purpose, a syringe was filled with 0.5 g of modified silica gel and the sample solution was drawn into the syringe and ejected back again. The analyte elements were quantitatively retained at pH 5. Then, the elements sorbed by the silica gel were eluted with 2.0 M of HCl and determined by GFAAS. At optimum conditions, the recovery of Cu, Cd and Cr were 96-98%. Detection limits (3delta) were 6.6, 7.5 and 6.0 micro g L(-1) for Cu, Cd and Cr, respectively. The elements could be concentrated by drawing and discharging several portions of sample successively but eluting only once. Cu, Cd and Cr added to a seawater sample were quantitatively recovered (>95%) in the range of the 95% confidence level. The method proposed in this paper was compared with a column technique. Optimum experimental conditions, reproducibility, precision and recoveries of both techniques are the same, but the syringe technique is much faster, easier and more practical than the column technique. It is a portable system and allows one to make the sorption process in the source of sample. In addition, the risk of contamination is less than in the column technique.