Saturated Solution Of Ammonium Chloride Research Articles

Application of cupric or ferric ions as environmentally benign oxidants to the chloride leaching of platinum from spent reforming catalysts

Recovery of precious metals has been considered due to their limited availability and resources, and the reduction of environmental hazards. In this study, the environmentally friendly chloride leaching method was used to recover platinum (Pt) from a spent reforming catalyst. Hydrochloric acid and sodium chloride were applied as the complexing agent and ferric or cupric chloride (FeCl3, CuCl2) was used as oxidants. Response surface methodology was implemented to investigate the influences of acid concentration (1–3 M), oxidant concentration (0.5–1.3 M), and temperature (70–90 °C) on the Pt extraction at a fixed duration of 3 h using two separate Box-Behnken experimental designs. Increasing temperature and acid concentration improved the Pt recovery from ∼52% to ∼89% in the presence of 1 M FeCl3, and from ∼29% to 94% in the presence of 0.75 M CuCl2. Generally, at low acid concentrations, ferric chloride was more efficient in Pt dissolution, while, at high acid concentrations, cupric chloride performed better. Finally, the platinum content of the pregnant leach solution was precipitated by adding a saturated ammonium chloride solution. According to the results of the X-ray diffraction analysis, the obtained precipitate was mainly composed of ammonium hexachloroplatinate, sodium chloride, and ammonium chloride. Also, the Pt assay of the powder was determined as 21%.

Межфазное распределение сорбиновой кислоты при экстракции сополимером N-винилформамида с 1-винил-3,5-диметилпиразолом

С целью изучения экстракции сорбиновой кислоты из объектов со сложной матрицей изучено межфазное распределение сорбиновой кислоты в системе сополимер N-винилформамид – 1-винил-3,5-диметилпиразол – хлорид аммония. Рассчитаны коэффициенты распределения и степень извлечения консерванта при различных соотношениях фаз и концентрации раствора сополимера. Установлено влияние рН на экстракцию сорбиновой кислоты, предложен механизм ее взаимодействия с экстрагентом. Определение сорбиновой кислоты в водно-солевой фазе осуществлено методом капиллярного электрофореза в выбранных условиях.
 
 
 
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Preparation, characterization, and evaluation of Moringa oleifera pod husk adsorbents for aqueous phase removal of norfloxacin

Chemically treated and carbonized adsorbents were prepared from Moringa oleifera pod husks (MPH) and evaluated for the aqueous phase removal of Norfloxacin (NOX), a common antibiotic. The pulverized precursor was steeped in a saturated ammonium chloride solution (24 h) to give the chemically treated adsorbent (AMPH). Pyrolysis of AMPH (623 K, ½ h) yielded the carbonized adsorbent (CMPH). Both adsorbents showed favorable physicochemical attributes (pH, bulk density, attrition, iodine adsorption number/surface area, titratable surface charge, and FT-IR analysis). NOX removal was studied under the effects of initial solution pH (2–11), adsorbent dosage (0.5–2.5 g), initial NOX concentration (5–25 mg/L), contact time (0–240 min), and temperature (298–328 K). Optimal NOX uptake (mg/g) by AMPH (1.42) and CMPH (1.88) occurred at solution pH 5 and adsorbent dose of 0.5 g. Equilibrium adsorption obeyed the Langmuir isotherm. Free energy change (ΔG°), enthalpy change (ΔH°), and entropy change (ΔS°) indicated that the adsorption of NOX was feasible, spontaneous, exothermic, and physisorptive. Kinetically, NOX uptake increased rapidly within the first 10 min for both adsorbents and overall, was well modeled by the Blanchard pseudo-second-order equation. The adsorbents may find use in the removal of microcontaminants of pharmaceutical origin from effluents/wastewater.

Aqueous phase removal of ofloxacin using adsorbents from Moringa oleifera pod husks

Chemically activated and carbonized adsorbents were prepared from Moringa oleifera pod husks (MOP), characterized and evaluated for their ability to remove a common antibiotic - ofloxacin (OFX) from aqueous solution. The pulverized precursor was steeped in a saturated ammonium chloride solution for a day to give the chemically activated adsorbent (AMOP). A portion of AMOP was pyrolyzed in a muffle furnace at 623 K for 30 min to furnish its carbonized analogue (CMOP). The adsorbents showed favorable physicochemical attributes. The effects of operational parameters such as initial OFX solution pH and concentration, adsorbent dosage, temperature and contact time on OFX removal were investigated. At equilibrium, optimal removal efficiencies of 90.98% and 99.84% were achieved at solution pH 5 for AMOP and CMOP, respectively. The equilibrium adsorption data fitted into both the Langmuir and Freundlich isotherms. Gibbs free energy change (G o ), enthalpy change (H o ) and entropy change (S o ) indicated that the adsorption of OFX was feasible, spontaneous, exothermic and occurred via the physisorption mode. Adsorption kinetics obeyed the Blanchard pseudo-second-order model. The results may find applications in the adsorptive removal of micro-contaminants of pharmaceutical origin from wastewater.

Two-Dimensional Nanosheets and Layered Hybrids of MoS2 and WS2 through Exfoliation of Ammoniated MS2 (M = Mo,W)

Ammoniated MS2 (M = Mo,W) have been synthesized by reacting LixMS2 with a saturated solution of ammonium chloride. While, largely neutral NH3 is present in the interlayer of ammoniated MoS2, equal amounts of NH3 and NH4+ ions are present in the tungsten analog. The ammoniated MS2 exfoliate readily in a variety of polar solvents with exfoliation being best in water. Ammoniated WS2 forms a more stable colloidal dispersion compared to the Mo analog because the ammonium ions do not deintercalate easily from the layers even on exfoliation. The dispersions are comprised of large nanosheets of MS2 with lateral dimensions in the order of micrometers. The layers could be restacked from the colloidal dispersions by evaporating the solvent. While the colloidal dispersions of ammoniated MoS2 yield NH3-free MoS2 on restacking, the dispersions of ammoniated WS2 yield WS2 intercalated with NH4+ ions. Co-stacking of MoS2 and WS2 nanosheets from a mixture of both the colloidal dispersions results in MoS2–WS2 hybrids in which the MoS2 and WS2 nanosheets are randomly stacked. Photoluminescence measurements of MS2 nanosheets and MoS2–WS2 hybrids indicate phase stability and existence of direct bandgap.

Paraquat quantification in deposits from drinking water networks

The aim of this work was to develop an expeditious analytical methodology to evaluate the paraquat (PQ) contamination level in deposits from drinking water networks. To the best of our knowledge, no other study has focused on this matter, which is of crucial importance, for instance, to obtain a fast response after a suspicion of contamination (emergency situation). Three deposits representative of those typically found in drinking water networks were used: two iron-based – S2 and S3, and a calcium rich one – S4. The analytical method consists of an easy and fast extraction step, using a saturated ammonium chloride solution, followed by direct injection in a high performance liquid chromatograph with a diode array detector (HPLC-DAD). A matrix-matched calibration was performed for paraquat, in the range of 5 to 193 μgPQ per g deposit, and a limit of detection of 0.1 μgPQ per g deposit was reached. The good percentages of recovery (90–101% on average) and the low relative standard deviations observed for the PQ–S3 system (3, 4 and 2% for 20, 80 and 160 μgPQ per g deposit, respectively) enable a reliable quantification of paraquat, even at the lowest contamination levels. The developed analytical methodology can also be extended for diquat and also proved to be suitable for paraquat quantification in other types of deposits.

Szilard-Chalmers and X-ray Absorption Spectroscopy to Locate Copper Cations in Synthetic Faujasite, Zeolite X

ABSTRACTThe sodium in synthetic faujasite, commercial zeolite-X, was exchanged with copper cations at room temperature. A maximum number of 70 out of 86 Na cations were replaced with 35 copper cations (1). The copper exchanged zeolite was divided in six equal parts. Five of them were calcined at 43, 73, 112, 150 and 195 deg C. After calcination the samples were eluted with saturated solution of ammonium chloride to remove copper cations from open sites (super-cages) of the zeolite (Fig 1). The remaining copper cations were in locked sites (sodalite-cages or hexagonal-prisms). Using XAS edge-jump as a measure of quantitative analysis, we found that 9.0, 11.5, 12.7, 13.3 and 20.0 copper cations were locked at calcination temperatures of 43, 73, 112, 150 and 195 deg C respectively. The analysis of the first shell Fourier Transformed radial distribution shows that cations at site I in the hexagonal-prism and site I ‘ and II ’ in the sodalite-cages, adjacent to site I, are distributed at equal proportion, independent of temperature.

THE ALKALOIDS OF TRIBULUS TERRESTRIS: A REVISED STRUCTURE FOR THE ALKALOID TRIBULUSTERINE

ISHS III WOCMAP Congress on Medicinal and Aromatic Plants - Volume 3: Perspectives in Natural Product Chemistry THE ALKALOIDS OF TRIBULUS TERRESTRIS: A REVISED STRUCTURE FOR THE ALKALOID TRIBULUSTERINE

Zinc-Promoted Reduction of 1,2-Diketones: A Simple, Efficient, and Mild Approach to a-Hydroxy Ketones

1,2-Diketones were readily converted to α-hydroxy ketones in high to excellent yields using zinc in saturated ammonium chloride solution.

New reactivity of functionalised organolithium compounds in the presence of Cu(I) or Cu(II) salts: conjugate addition, acylation or dimerisation

The reaction of functionalised organolithium compounds 1 with electrophilic olefins 2 in the presence of copper(I) iodide and HMPA in THF at −78°C leads, after hydrolysis with a saturated solution of ammonium chloride, to the corresponding products 3 resulting from a conjugate addition. The same process but using an acyl chloride instead of the electrophilic olefins affords the expected ketone 4 from an acylation process. Finally, when intermediates 1 are treated with copper(II) chloride in THF at −78°C, the corresponding dimers 5 are isolated after the same hydrolytic treatment.

The corrosion behavior of AISI 310 stainless steel in thiosulfate ion containing saturated ammonium chloride solution

The effect of thiosulfate ion on the corrosion behavior of 310 SS in saturated ammonium chloride and 5 M sodium chloride solutions, with or without the addition of 0.01 M sodium thiosulfate, was investigated. Potentiodynamic polarization curves showed that a delayed pitting corrosion was found in saturated ammonium chloride solution as compared with that in 5 M sodium chloride solution. The addition of 0.01 M sodium thiosulfate to the saturated ammonium chloride solution caused a substantial effect on the electrochemical behavior. At the potential in the range of −0.35 to +0.15 V, both the anodic polarization curves and the microscopic observation indicated that S 2 O = 3 participated in the electrochemical reactions. The anodic current density increase sharply and sulfide was formed on the specimen surface in this potential range. However, once the potential was greater than 0.15 V, the current density decreased and a secondary passive behavior exhibited in the polarization curve. The synergistic effect of Cl − and S 2 O = 3 on pitting corrosion of 310 SS is also discussed.

Acidic and neutral drugs screen in blood with quantitation using microbore high-performance liquid chromatography–diode array detection and capillary gas chromatography–flame ionization detection

Blood previously acidified with aqueous saturated ammonium chloride solution was extracted with ethyl acetate. The dried extract was subjected to acetonitrile–hexane partition. The acetonitrile portion was analysed for the presence of acidic and neutral drugs by HPLC–DAD (200 mm×2.1 mm I.D. microbore ODS-Hypersil column) and GC–FID (25 m narrow-bore×0.25 mm I.D. HP-5 column with 0.33 μm film thickness). The protocol was found to be suitable for both clinical toxicology (including emergency toxicology) and postmortem toxicology. At least 66 drugs of interest were unequivocally identified by RRTs (HPLC) and UV spectra (DAD) match while another 12 were unequivocally identified by double RRTs match (HPLC and GC). Quantitation was facilitated by incorporating calibration blood standards in each assay batch. The five drugs most commonly encountered in clinical blood specimens (1150 cases) were: paracetamol (47.4% of the cases); chlormezanone (6.6%), theophylline (1.74%), naproxen (1.65%) and mefenamic acid (1.56%). The following drugs were detected in toxicologically significant quantities in postmortem blood specimens (245 cases): phenobarbitone (1.22% of the cases), naproxen (0.82%), chlormezanone (0.82%), theophylline (0.82%), carbamazepine (0.41%) and paracetamol (0.41%).

Synthesis and biological activity of amides and N-arylamidines of 2-alkoxy-5,6,7,8-tetrahydroquinoline-3-carboxylic acids

2-Alkoxy-5,6,7,8-tetrahydroquinoline-3-earboxamldes (I-VI). To a solution of sodium alc0holate prepared from 0.03 mole of sodium in 25 ml of the corresponding alcohol was added 4.2 g (0.02 mole) of 2-chloro-5,6,7,8-tetrahydroquinoline-3carboxytic acid [3] and the reaction mixture was heated in a water bath for 8-10 h. The alcohol was evaporated, the residue was washed with water, dried, and crystallized from ethanol. N-Aryl Amidines of 2-Methoxy-5,6,7,8-tetrahydroquinoline-3-carboxylic Acid (VII-X1). To an ethereal solution of arylaminodimagnesium prepared from 0.05 mole of magnesium, 0.05 mole of EtBr, and 0.025 mole of arylamine was added 4.7 g (0.025 mole) of 2-methoxy-3-cyano-5,6,7,8-tetrahydroquinoline [2] in absolute ether. The reaction mixture was heated for 3 h, and after cooling, a saturated solution of ammonium chloride was added, the ether layer was separated, washed with water to neutrality, and dried with magnesium sulfate. The ether was evaporated and the residue was crystallized from hexane or cyclohexane.

Rare-earth ion exchange in zeolite Y

Isotherms, Kielland plots and separation factors have been obtained for the exchange of La 3+, Ce 3+, Y 3+ and Lu 3+ at 25°C and 65°C in NaY zeolite. Thermodynamic parameters have been calculated from these data. The efficiency of removal of La 3+, Ce 3+, Tb 3+, Yb 3+ and Lu 3+ rare-earth ions from the supercage sites with a saturated solution of ammonium chloride has been determined at room temperature.

Interphase partition in systems containing anomalous mixed crystals Communication 5. The systems NH4Cl-CdCl2-H2O and NH4Cl-NiCl2- H2O

1. The system NH4Cl-CdCl2-H2O differs radically from all previously studied systems formed by ammonium and heavy-metal chlorides, for in this case reduction in the cadmium concentration of the solution is associated with rise in the partition coefficient, which tends to infinity. 2. The system NH4Cl-NiCl2-H2O is similar to the analogous iron system, for reduction in the nickel concentration of the original solution is associated with a fall in the partition coefficient, which tends to zero. This indicates that the nickel system has a lower formation limit. 3. Greenberg and Walden's scheme, which satisfactorily explains the behavior of bivalent manganese and copper in their partition between crystals and saturated solution of ammonium chloride, is not applicable to the cadmium and nickel systems.

Studies on the Biology of the Argasid Tick, Ornithodoros nicollei Mooser

Distribution: Mexico: States of Guerrero, Puebla, Colima, and Jalisco (Mooser, 1932; Brumpt, Mazzotti and Brumpt, 1939; Mazzotti, 1942). Hosts-Habitats: Neotoma, man, and dogs; also found on a rattlesnake in the Zoo in St. Louis, Missouri. Native houses in Mexico. Feeding time: These ticks feed readily on mice and guinea pigs. Larvae may engorge and detach voluntarily in less than 15 minutes or they may remain attached for several days before completing engorgement. Nymphs and adults completed engorgement in from 15 to 23 minutes. Molting: June 8 to 11, 1942 eighty-five larvae2 completed engorgement on a guinea pig. They were placed separately in shell vials, numbered serially, and accurate records made until all surviving ticks reached the adult stage. This requires individual feeding in all nymphal stages. The ticks were stored at room temperature in humidity jars containing a saturated solution of ammonium chloride. All larvae molted in 9 to 13 days; first nymphs in 8 to 11; second nymphs in 6 to 20; third nymphs in 7 to 14; fourth nymphs in 11 to 39; fifth nymphs in 12 to 48, and 3 sixth nymphs in 21 days. The spread in molting time was greatest in the fourth and fifth nymphal stages and perhaps more nearly approaches conditions in nature as these ticks detach easily when disturbed and the degree of engorgement influences molting time. Nymphal stages: As in several other species of Ornithodoros, the period of the greatest mortality was during the larval molt. In this series 18 ticks died at the time of the larval molt and three at the first nymphal molt. Sixty-four were reared to adults (37 Sc, 27 59). The first adult, a male, appeared 70 days following the larval feeding and the last, a female, at 160 days. Following the fourth nymphal molt there were 31 ce1 and 2 $?; at the fifth, 6 additional males and 22 females, and at the sixth, 3 females. Oviposition: Observations were made on 21 females, 12 of which were reared and 9 as received from Mexico. Data on the preoviposition period-time from the last engorgement to the appearance of the first egg-indicate a definite trend toward a resting period during the summer months. This is in marked contrast to certain northern species which show a similar period of inactivity during the winter months. As a rule, females that engorged in late autumn began egg-laying in a much shorter time than females engorged in the spring. Of 16 females engorged in November, 11 began oviposition in 15 days or less; the shortest interval was 7 days. On the other hand, 3 females engorged, respectively, in April, May, and July began to oviposit in November, November, and December. The periods were accurately observed in 36 instances; these varied from 7 to 233 days.