Transport of Cr(VI) from HCl Media Using (PJMTH+Cl−) Ionic Liquid as Carrier by Advanced Membrane Extraction Processing

The transport of Cr(VI) from acidic media through pseudo-emulsion based membrane strip dispersion (PEMSD) containing the ionic liquid (PJMTH⁺Cl^?) as carrier in the form of a pseudo-emulsion with sodium hydroxide has been investigated. The ionic liquid was generated in situ by reaction of the primary amine Primene JMT and HCl. The transport of Cr(VI) is evaluated as a function of various experimental variables: stirring speed in the feed phase, concentration of Cr(VI) and HCl in the feed phase, carrier concentration, and organic diluents in pseudo-emulsion, and NaOH concentration in pseudo-emulsion as strippant. In PEMSD, pseudo-emulsion is an emulsion that is formed temporarily between the organic and the stripping solutions. Both solutions are separated when the stirring device is stopped. The value of the overall permeation coefficient obtained under standard experimental conditions was 3.1 × 10^?3 cm s^?1, whereas the transport process is controlled by diffusion of chromium species in the stagnant film of the feed phase. The performance of the system against other carriers (amines, quaternary phosphonium salt and quaternary ammonium salt) was also evaluated.     

Ozone Solubility in Aqueous Solutions of NaCl,Na2SO4, and K2SO4: Application of the Weisenberger-Schumpe Model for Description of Regularities and Calculation of the Ozone Molar Absorption Coefficient

The ozone solubility in aqueous solutions of salts, NaCl (up to 5 М) and Na₂SO₄ (up to 2 М) and their mixtures, was studied. The results are adequately described by the semi-empirical model proposed by Weisenberger and Schumpe for calculation of the solubilities of atmospheric gases in concentrated solutions of electrolytes. By comparing the data obtained experimentally and calculated in terms of the Weisenberger and Schumpe model, the ozone molar absorption coefficient was found to be ε = 2860 ± 200 M^?1 cm^?1 at 260 nm.     

Chemical Pretreatments Affecting Drying Characteristics of Chilli (cv. Huarou Yon)

One- (70°C) and two-temperature regimes (70 and 50°C) were used to dry chilli (Capsicum annuum cv. Huarou Yon) using a laboratory tray dryer compared to conventional sun drying. A pretreatment was done by soaking chilli in antibrowning solutions before drying. It was found that the drying rate of chilli soaked in chemical solutions was increased and the drying period of chilli was decreased. Page's model was found to fit well with the experiment for one- and two-temperature drying using least squares analysis. The highest value of the coefficient of determination (R² > 0.99), the lowest value of standard error of estimation (SEE < 0.00031), and the lowest value of the mean relative deviation (P < 10%) were obtained. The effective moisture diffusivities of chilli drying at 70°C and two-stage drying were between 6.01–7.22 × 10^?10 m²/s and 3.16–3.89 × 10^?10 m²/s, respectively. In contrast, the lowest value of effective moisture diffusivity of chilli was obtained by the conventional sun-drying method (0.597 × 10^?10 m²/s). The highest value of moisture diffusivity was observed for chilli soaked in sodium metabisulfite (NaMS) mixed with CaCl₂ solution for both one- and two-temperature regimes. The color of chilli was improved by using chemical pretreatments, in particular, chilli soaked in NaMS mixed with CaCl₂ solution.     

Copper Biosorption on Magnetically Modified Yeast Cells Under Magnetic Field

Brewer's yeast (bottom yeast, Saccharomyces cerevisiae subsp. uvarum) cells were magnetically modified using water-based magnetic fluid stabilized perchloric acid. The magnetically modified yeast cells were characterized by scanning electron microscopy (SEM). Cu²⁺ biosorption properties of magnetically modified yeast cells from synthetic solutions were utilized in a continuous magnetic system. The Cu²⁺ ion-binding capacity decreased drastically with the increase of the flow rate. The maximum Cu²⁺ biosorption capacity was obtained to be 1.2 mmol/g at 25°C. Biosorption of Cu²⁺ increased with increasing pH and then reached almost a plateau value around pH 4.0. The yeast biomass can be easily regenerated by 0.1 M HNO₃ with higher effectiveness. Biosorption of heavy metal ions from artificial wastewater was also studied. The biosorption capacities are 0.92 mmol/g for Cu²⁺, 0.52 mmol/g for Hg²⁺, and 0.28 mmol/g for Ni²⁺. Magnetically-modified yeast cells exhibits the following metal ion-affinity sequence: Cu²⁺ > Hg²⁺ > Ni²⁺.     

ANALYTIC SOLUTIONS FOR MHD FLOWS OF AN OLDROYD-B FLUID BETWEEN TWO SIDEWALLS PERPENDICULAR TO THE PLATE

This study is concerned with analytic solutions of some magnetohydrodynamic (MHD) flows of an Oldroyd-B fluid. The fluid is assumed to be electrically conducting in the presence of a uniform magnetic field and occupies the space over a flat plate between two sidewalls perpendicular to the plate. The governing equation of motion is treated analytically, yielding the derivation of exact solutions under integral and series form. By assigning numerical values to various parameters, the integrals encountered are evaluated numerically. In the absence of sidewalls, all solutions that have been obtained reduce to those corresponding to the motion over an infinite plate. The impacts of several quantities are investigated on the resulting velocity field and the tangential stress at the bottom wall.     

Biosorption of aquatic Pb2+, Hg2+, and Cd2+ using a combined biosorbent—Aspergillus niger-Treated Rice Straw

The biosorbent used for removal of Pb²⁺, Hg²⁺, and Cd²⁺ from aqueous solutions was rice straw fermented by Aspergillus niger (ARS), and raw rice straw (RRS) was used as a control. When inoculum size, material–water ratio, and temperature were 10⁶, 100%, and 303K, respectively, the optimized spore number was 10⁹. The ARS exhibited a lager pore biosorption, which was better than RRS. The biosorption mechanism was involved in chelation with functional groups such as C-H, C = O, C-O, and C = C, and the biosorption data obtained were well described by the pseudo-second-order kinetic equation and the Freundlich isotherm model.     

Capacitor Applications of Nanocomposite Films for Poly(3,4-ethylenedioxythiophene-co-pyrrole)/Multi-Walled Carbon Nanotubes and Poly(3,4-ethylenedioxythiophene-co-pyrrole)/Copper Oxide

Polypyrrole/multi-walled carbon nanotube, poly(3,4-ethylenedioxythiophene)/multi-walled carbon nanotube and their nanocomposites P(EDOT-co-Py)/multi-walled carbon nanotube and P(EDOT-co-Py)/copper (II) oxide, (CuO) in the initial feed ratio of [EDOT]₀/[Py]₀ = 1/5 were electrosynthesized on glassy carbon electrode by cyclic voltammetric method. Their characterizations were performed by cyclic voltammetric, Fourier transform infrared-attenuated total reflectance, scanning electron microscopy, energy dispersion X-ray analysis, and electrochemical impedance spectroscopy. To the best of authors’ knowledge, the first report on polypyrrole/multi-walled carbon nanotube, PEDOT/multi-walled carbon nanotube, P(EDOT-co-Py)/multi-walled carbon nanotube and P(EDOT-co-Py)/CuO nanocomposite films were comparatively examined in 0.1 M NaClO₄/CH₃CN and in 0.1 M sodium dodecyl sulfate solutions. The highest specific capacitance for PEDOT/multi-walled carbon nanotube and polypyrrole/multi-walled carbon nanotube composite films were obtained as C_sp = 306 mF × cm^?2 for 3% multi-walled carbon nanotube and C_sp = 804 mF × cm^?2 for 1% multi-walled carbon nanotube, respectively. The highest specific capacitances were obtained as C_sp = 27.40 mF × cm^?2 and C_sp = 26.90 mF × cm^?2 for P(EDOT-co-Py)/multi-walled carbon nanotube includes the wt percent of 1% multi-walled carbon nanotube and P(EDOT-co-Py)/CuO includes the wt percent of 3% CuO, respectively. The C_sp of P(EDOT-co-Py)/CNT composite films were calculated as 9.43 and 11.49 mF × cm^?2 for 3 and 5% multi-walled carbon nanotube, respectively. In addition, The EIS results were simulated with the equivalent circuit model of R_s(C_dl1(R₁(QR₂)))(C_dl2R₃).     

Equilibrium,kinetic, and thermodynamic studies of the Ca2+ and Mg2+ ions removal from water by Duolite C206A

The uptake of Ca²⁺ and Mg²⁺ ions from synthetic aqueous solutions by Duolite C206A was studied in static-batch mode. Results revealed that there is no need of pH adjustment. The equilibrium is reached after 30 min with 0.5 g of resin at 25°C. Equilibrium data were well fitted by Langmuir isotherm model. Maximum uptake capacities Q_max were about 23.04 mg Mg²⁺/g and 64.10 mg Ca²⁺/g. The pseudo-second-order model was found as the best to explain the ions exchange kinetics effectively. The uptake of Ca²⁺ and Mg²⁺ ions by Duolite C206A is exothermic and the process is spontaneous.     

INFLUENCE OF K+ AND NA+ IONS ON DIRECT ELECTROSYNTHESIS OF SOLID K2FEO4 AND COMPARISON OF THE PHYSICOCHEMICAL PROPERTIES OF K2FEO4 SAMPLES

The influence of K⁺ and Na⁺ ions on the direct electrosynthesis of solid K₂FeO₄ was investigated in 14 M OH^? solutions. At 50 or 60°C, the maximum current efficiency of electrosynthesis is obtained in 9 M KOH +5 M NaOH solution. The maximum current efficiency of 64.9% is obtained at 60°C in 9 M KOH +5 M NaOH solution, similar to the maximum value of 63.9% at 70°C in 14 M KOH solution in the temperature ranges studied. The result shows that the temperature at which the maximum current efficiency is obtained in 9 M KOH +5 M NaOH is much lower than that in 14 M KOH. Solid K₂FeO₄ powders directly electrosynthesized in 9 M KOH +5 M NaOH and 14 M KOH solutions were characterized by Fourier transform-infrared spectrometry (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD), and their electrochemical performance was investigated by means of galvanostatic discharge. The result shows that the two samples have similar physical properties and discharge performance.     

Correlation between cell surface physicochemical properties of bacterial strains and their chromium removal potential

Physicochemical characterization of microbes has gained recently a great interest by scientific community. It is proved of extreme importance in several fields of science and technology applications such as bioremediation. In this work, we investigated the establishment of a possible correlation between chromium removal capacity of seven bacterial strains isolated from contaminated sites with industrial wastes including tanning processing and their cell surface physicochemical properties. Thus, hydrophobicity and donor/acceptor electrons character were obtained using contact angle measurements. Statistical analysis showed a high significant positive correlation between hexavalent chromium (Cr(VI)) removal by the strains and their acceptor electron character γ⁺(r = 0.90). While significant negative correlation between the Cr(VI) removal potential and the ΔGiwi value (r = ?0.844) and also with their donor electron character γ^? (r = ?0.746) were observed. These results may contribute to determine a selectrion criteria of bacteria that can be operated in bioremediation applications.     

Aggregation in Solvent Extraction Systems Containing a Malonamide,a Dialkylphosphoric Acid and their Mixtures

Abstract

Aggregation phenomena in n-alkane solutions of di-n-hexylphosphoric acid (HDHP), N,N′-dimethyl-N,N′-dioctylhexylethoxymalonamide (DMDOHEMA), and their mixtures, were investigated by electrospray ionization–mass spectrometry (ESI-MS), vapor pressure osmometry (VPO), and small-angle X-ray and neutron scattering (SAXS and SANS). The objective of the study was to probe the formation of mixed HDHP-DMDOHEMA species before and after extraction of trivalent lanthanide and actinide (M³⁺) nitrates. The most important species formed by HDHP upon metal extraction has the composition M(DHP)₃(HDHP)₃(H₂O). These species exist as spherical aggregates of the reverse micelle type with a polar core diameter of ～ 7 Å and total diameter of ～ 11 to ～ 15 Å. The aggregation of DMDOHEMA is a progressive phenomenon, with an average aggregation number of ～ 2 in the 0.2 to 0.6 M range and larger aggregates forming at higher concentrations. The metal loaded DMDOHEMA aggregates can be considered as interacting spheres with a polar core diameter between ～ 11 and ～ 16 Å, depending on composition, a total diameter of up to ～ 25 Å, and a weight-average aggregation number of ～ 9. The results obtained in this work provide strong evidence for the formation of mixed aggregates when mixtures of HDHP and DMDOHEMA are used for the extraction of trivalent Ln and An cations. These mixed reverse micelles have a diameter between 19 and 24 Å with a polar core diameter of 10 and to 14 Å. The most recurrent micellar composition is 2 HDHP and either 4 or 5 DMDOHEMA molecules.     

Biosorption of Strontium Ions by Magnetically Modified Yeast Cells

The sorption of Sr²⁺ ions from aqueous solutions on magnetically modified fodder yeast (Kluyveromyces fragilis) cells and their subsequent desorption were studied. The Sr²⁺ sorption increased with increasing pH and reached a plateau between pH 4.0 and 7.0. The changes of temperature slightly influenced the sorption process. The sorption values were 19.5 mg g^?1 and 53.5 mg g^?1 for 10 mg L^?1 and 40 mg L^?1 Sr²⁺ solutions respectively after 20 min incubation at a pH higher than 4. The Langmuir isotherm was successfully used to fit experimental data; the maximum adsorption capacity was 140.8 mg g^?1 under optimal conditions. The adsorbed Sr²⁺ ions can be desorbed with nitric acid (0.1 mol L^?1).     

Equilibrium,Thermodynamic and Kinetic Studies on Biosorption of Mercury from Aqueous Solution by Macrofungus (Lycoperdon perlatum) Biomass

The present research is to investigate the possibility of macrofungus Lycoperdon perlatum biomass, which is an easily available, renewable plant, low-cost, as a new biomass for the removal of mercury (Hg(II)) ions from aqueous solutions. The effects of various parameters like pH of solution, biomass concentration, contact time, and temperature were studied by the using the batch method. The Langmuir model adequately described the equilibrium data. The biosorption capacity of the biomass was found to be 107.4 mg · g^?1 at pH 6. The mean free energy value (10.9 kJ · mol^?1) obtained from the D–R model indicated that the biosorption of Hg(II) onto fungal biomass was taken place via chemical ion-exchange. Thermodynamic parameters showed that the biosorption of Hg(II) onto L. perlatum biomass was feasible, spontaneous, and exothermic in nature. The kinetic results showed that the biosorption of Hg(II) onto fungal biomass followed second-order kinetics. This work also shows that L. perlatum biomass can be an alternative to the expensive materials like ion exchange resins and activated carbon for the treatment of water and wastewater containing mercury ions due to its ability of selectivity and higher biosorption capacity and also being low cost material.     

Uranyl Ion Uptake from Aqueous Solutions by Chemically Cross-linked Polyelectrolyte CAMA Hydrogels

Uranyl ion adsorption from aqueous solutions has been investigated by chemically cross-linked polyelectrolyte acrylamide/maleic acid (CAMA) hydrogels. CAMA hydrogels with various compositions were prepared from ternary mixtures of acrylamide (A), maleic acid (MA), and water by free radical polymerization in aqueous solution using multifunctional cross-linkers such as ethylene glycol dimethacrylate (EGDMA) and 1,4-butanediol dimethacrylate (BDMA). Uranyl ion adsorption from aqueous solutions was studied by batch sorption technique at 25°C. The effect of uranyl ion concentration and mass of adsorbent on the uranyl ion adsorption were examined. In the experiments of the sorption, L type sorption in the Giles classification system was found. Some binding parameters such as initial binding constant (K _i ), equilibrium constant (K), monolayer coverage (n), site-size (u), and maximum fractional occupancy (Ô) for CAMA hydrogel-uranyl ion binding system were calculated by using Langmuir linearization method. Finally, the amount of sorbed uranyl ion per gram of dry hydrogel (q) was calculated to be 3.29 × 10^?4 ? 15.87 × 10^?4 mol uranyl ion per gram for CAMA hydrogels. Adsorption of uranyl ion was changed range 8.17–48.10%.     

Multivariate Optimization and Adsorption Characterization of As(III) by Using Fraxinus Tree Leaves

This study introduces Fraxinus tree leaves as a new, efficient biosorbent of As(III). A suitable response surface was achieved by running a central composite design. Simultaneous optimization of both responses (R% and q) was carried out and 67% of the goal of desirability function was attained. The results obtained for simultaneous optimization are R = 70% and q = 80.6 mg g^?1 with 67% desirability in m = 600 mg L^?1 where s = 0.10 g and pH = 3.9. Langmuir and Freundlich isotherms model were applied in explaining the sorbent–sorbate equilibrium study, and maximum capacity uptake equals 99.97 mg g^?1 and K_L = 0.05 L mg^?1 has been obtained. Fourier Transfer Infra-Red (FT-IR) and kinetic results were considered to examine the functional groups involved and the adsorption mechanism.     

Chemometric analysis of selective polyphenolic groups in Asparagus racemosus (Shatavar) root extracts by traditional and supercritical fluid (CO2) based extractions

ABSTRACT

Asparagus racemosus root extracts were prepared by supercritical fluid (CO₂), soxhlet, and maceration-based methods also with various pretreatments. Thereafter, these root extracts were analyzed by High-Performance Liquid Chromatography, along with the chemometric study of the disparate phenolic groups. Among these, supercritical fluid (CO₂) based extract has a larger number of polar compounds and the antioxidant activity (98.54 ± 0.22 µM Trolox equivalent mg^?1). It also has the best cell viability (94.37 ± 1.12%) and insulin release (0.82 ± 1.12 ng mL^?1) on β-pancreatic RINm-5F cells whereas, the best extractive yield (75.80 ± 3.44% w/w) was observed for pretreated aqueous soxhlet-based extract.     

DETERMINATION OF THE METASTABLE ZONE WIDTH OF GLYCINE AQUEOUS SOLUTIONS FOR BATCH CRYSTALLIZATIONS

The aim of this study was to determine the metastable zone width of aqueous solutions of glycine for non-seeded batch crystallizations. The saturation curve was determined by studying the heating rate influence on the apparent saturation temperatures of several solutions. A linear regression was then applied to obtain the saturation temperatures. The spontaneous nucleation curve was obtained by measuring the crystallization temperatures of several solutions at different cooling rates. The results show that the apparent nucleation order of the glycine aqueous solutions was around 3.5 ± 0.5. Moreover, from the experimental data, a second-order polynomial model was established by using the experimental design method. This model enables the expression of crystallization temperature to be defined as a function of concentration and cooling rate. The results show that the model fits well (R² > 0.99; Q² > 0.98) and that the cooling rate is the most influential parameter.     

Determination of Cd(II), Co(II), Cu(II), Ni(II), and Pb(II) Ions by FAAS after Separation/Preconcentration using Amberlite XAD‐1180 Chelating Resin Chemically Modified with o‐Aminophenol

Abstract

The use of a newly synthesized chelating resin with an o‐aminophenol–type functional groups and Amberlite XAD‐1180–type supporting material for separation/preconcentration of trace metal ions from various water samples was described. Amberlite XAD‐1180‐o‐aminophenol chelating resin (XAD‐o‐AP) was synthesized using Amberlite XAD‐1180 resin as solid support and o‐aminophenol as the chelating ligand. The determination of Cd(II), Co(II), Cu(II), Ni(II), and Pb(II) ions was made by flame atomic absorption spectrometry (FAAS). Studying with model solutions for the optimization of the method was based on the measurement of recovery values (between 92–106%) of the analyte elements. Some analytical parameters such as pH (6.0), volume of the sample (～250 mL), effect of matrix ions, flow rates of the sample (2.5 mL min^?1) and elution solutions (2.5 mL min^?1), concentration, type and volume of the eluent (4 mol L^?1 HNO₃, 20 mL) were investigated. The detection limit (3s/b, n=20) and the relative standard deviation (n=7) of the method were found to be in the range 0.9–4.3 µg L^?1 and 4.4–5.5%, respectively. The proposed method was successfully applied to the real samples such as wastewater, boiler feeding water and a certified reference material (Estuarine water, LGC 6016).     

Harvesting of Cyanobacterium Arthrospira platensis Using Inorganic Filtration Membranes

Abstract

The present work deals with the concentration and the separation of Arthrospira platensis from a diluted culture medium. Among the different ways to operate this liquid/solid separation, this paper is focused on the membrane alternative. The general framework of this experimental study is the MELISSA project from the European Space Agency (ESA) for the development of life support systems in Space. The performances of fourteen inorganic membranes (microfiltration and ultrafiltration) were evaluated. According to the results, the operating conditions and the influence of phycocyanin and exopolysaccharides on the fouling phenomenon were investigated on the best membrane. A critical aspect to monitor along the process is the quality of the product in terms of composition of the main cell macro‐components, such as proteins and exopolysaccharides. The ultrafiltration membrane ATZ‐50 kD exhibited the best permeation flux and cleanability. An increase of fluid velocity and transmembrane pressure is energy‐consuming. A good compromise between this consideration and the gain in terms of permeation flux is close to 3 m · s^?1 and 2 · 10⁵ Pa with the selected membrane and with a cyanobacteria suspension concentration ranging from 50 mg · L^?1 to 1 g · L^?1.     

Preconcentration and Determination of Metal Ions in Commercial Ethanol Used as Fuel for Automotive Engines

Abstract

The present investigation reports the synthesis, characterization, and adsorption properties of a new nanomaterial based on organomodified silsesquioxane nanocages. The adsorption isotherms for CuCl₂, CoCl₂, ZnCl₂, NiCl₂, and FeCl₃ from ethanol solutions were performed by using the batchwise method. The equilibrium condition is reached very quickly (3 min), indicating that the adsorption sites are well exposed. The results obtained in the flow experiments, showed a recovery of ca. 100% of the metal ions adsorbed in a column packed with 2 g of the nanomaterial, using 5 mL of 1.0 mol L^?1 HCl solution as eluent. The sorption‐desorption of the metal ions made possible the development of a method for preconcentration and determination of metal ions at trace level in commercial ethanol, used as fuel for car engines. The values determined by recommended method for plants 1, 2, and 3 indicated an amount of copper of 51, 60, and 78 µg L^?1, and of iron of 2, 15, and 13 µg L^?1, respectively. These values are very close to those determined by conventional analytical methods. Thus, these similar values demonstrated the accuracy of the determination by recommended method.