Ammoniacal Medium Research Articles

Development of a Spectroscopic Method for the Determination of Oxcarbazepine Using Green Synthesized Silver Nanoparticles

The present work describes the development of efficient spectroscopy-based analytical method for the determination of oxcarbazepine (OXC) using silver nanoparticles. The proposed method is simple, accurate, and reproducible. It employs green synthesized silver nanoparticles for the detection and estimation of OXC. In the estimation method, aliquots of OXC are made to react with silver nanoparticles in an ammoniacal medium to produce a yellow color that can be measured spectrophotometrically. A calibration curve was plotted that showed a linear response in absorbance with an increase in the concentration of the drug. The method is then validated for precision and accuracy according to ICH guidelines. Different parameters like optimized reagent concentrations, sequence of addition of reagents, the effects of temperature, pH, and waiting period before spectroscopic analysis are performed. The method was also tested for intra-day and inter-day precision and the effect of excipients to assess its ruggedness.

Assessment of the compounds formed by oxidative reaction between p-toluenediamine and p-aminophenol in hair dyeing processes: Detection, mutagenic and toxicological properties

Previous studies have demonstrated the presence of precursors and coupling agents in wastewater from hair dyeing processes. The complex reaction involved in the oxidation of these compounds can generate extremely hazardous sub-products, leading to an increase in the mutagenicity and toxicity of wastewater. Without proper treatment, this highly toxic wastewater may find its way into the drinking water treatment plant. The present work aimed to investigate the main products generated after the oxidation reaction involving p-toluenediamine (PTD) and p-aminophenol (PAP) – precursors that widely used in the composition of commercial permanent hair dyes, under experimental conditions close to the routine hair dyeing process (in the presence and absence of hydrogen peroxide in ammoniacal medium), using spectroscopic techniques. The study also investigated the mutagenicity and toxicity of the products formed in the hairdressing wash water and conducted detection analysis to determine the presence of the precursors and Bandrowski's Base Derivative (BBD) in samples of wastewater, surface and drinking water using HPLC-DAD and linear voltammetry techniques. Based on this investigation, we identified several PTD and PAP self-oxidation products and eleven sub-products derived from the reaction between PTD and PAP. Assays conducted using Salmonella typhimurium YG1041, with and without activation-induced rat liver metabolism (S9), indicated mutagenicity of the reaction products in concentrations above 10.0 μg μL−1. The concentrations of PTD, PAP, and several reactions and oxidation products of these precursors were detected in wastewater and water samples.

Enargite leaching under ammoniacal media with sodium persulfate and consecutive precipitation of As/Cu with Na2S/NaHS

Enargite ore (Cu3AsS4) is generally processed via pyrometallurgy, with high temperatures that release toxic arsenic (AsxOy) and sulfur (SOx) gases. In seeking alternatives that avoid production of noxious gases, this paper discusses batch leaching experiments of mineral mixtures of enargite and pyrite (Cu3AsS4 and FeS2), agitated under ammoniacal media (NH4OH) using sodium persulfate (Na2S2O8) as an oxidant. The results showed that almost complete leaching of enargite (98%) could be obtained due to the elimination of passivation (S°) by the action of the oxidant. With the help of a deep thermodynamic study and with DRX analysis, it was possible to establish the reaction mechanisms of dissolution of enargite with persulfate in an ammoniacal media. Leaching action selected for enargite, not affecting pyrite present. Enargite leaching can be represented under a heterogeneous kinetic model of reactant diffusion through a porous layer formed at reaction time. Orders of reaction 2.0 and 1.5, for persulfate and ammonium hydroxide concentrations, respectively, were established. Activation energy was calculated at 45.0 kJ/mol. Consecutive evaluations showed that metals present (Cu and As) could be precipitated with sodium sulfide and sodium hydrosulfide at 99% yields, thus generating a solution rich in ammonia that can be re-used in leaching.

Recovery of copper and nickel from ammoniacal medium through double supported liquid membranes containing N902 as carrier

In this paper, simultaneous recovery and separation of copper and nickel from ammoniacal medium through double supportedliquid membranes containingN902 as carrier were investigated. The results show that copper was continuously transported across double membranes, but nickel only was transported throughone of them. Therefore, more than92.4% of nickel and 94.0% of copperinthe mixed feed phase wereseparated into the twodifferent strip phaseswitha transporttime of 30 hoursunder the conditions:6 g/L and 180 g/L H2SO4 solutions as two different strip phases, 100 mg/L each of two metals dissolved in 2.0 mol/L total ammoniacal solution as the feed phase, and 25 vol.%N902 as the carrier in two membranes.

Potentiodynamic Polarization Behavior and Microscopic Examination of Tungsten Carbide Hard Metal Materials in Supported Ammoniacal Medium

Potentiodynamic Polarization Behavior and Microscopic Examination of Tungsten Carbide Hard Metal Materials in Supported Ammoniacal Medium

Potentiodynamic Polarization Behavior and Microscopic Examination of Tungsten Carbide Hard Metal Materials in Supported Ammoniacal Medium

Potentiodynamic Polarization Behavior and Microscopic Examination of Tungsten Carbide Hard Metal Materials in Supported Ammoniacal Medium

Assessment of p-aminophenol oxidation by simulating the process of hair dyeing and occurrence in hair salon wastewater and drinking water from treatment plant

This work reports the study of oxidation reaction of p-aminophenol (PAP) in ammoniacal medium in dissolved atmospheric oxygen and hydrogen peroxide, simulating the process of hair dyeing with permanent dyes. The products formed, which included semi-quinoneimine radical, quinoneimine, dimers, trimers and tetramers, were identified by mass spectrometry, infrared spectroscopy, UV–vis spectrophotometry, and nuclear magnetic resonance of hydrogen. The process was found to involve an autoxidation mechanism. The mutagenicity of the products was carried out by Salmonella Typhimurium YG1041 assay, and the results indicated no mutagenic properties. The presence of PAP and its oxidative products in samples of wastewater collected from hairdressing salon effluent (WW), raw river water (RRW), and water inlet and outlet of drinking water treatment plant (DWTP) was analyzed by HPLC-DAD. PAP was detected in the collected samples of WW, water samples from DWTP (before and after treatment), at concentrations of 2.1 ± 0.5 mg L−1, 1.9 ± 0.3 × 10-3 mg L−1 and 1.3 ± 0.2 × 10-3 mg L−1, respectively. The reaction products, including dimers, trimers and tetramers were identified only in the WW sample; this shows that both the precursor in the sample and its derivatives were released into the wastewater.

Assessment of the autoxidation mechanism of p-toluenediamine by air and hydrogen peroxide and determination of mutagenic environmental contaminant in beauty salon effluent

The present work investigated the autoxidation reaction of p-toluenediamine (PTD) - a precursor - widely used in permanent hair dyeing formulation, under experimental conditions close to the hair dyeing process (oxygen and/or peroxide in ammoniacal medium), by chromatographic and spectroscopic techniques. In additional, evaluated the mutagenicity of the PTD oxidation products and the presence of PTD and this products in wastewater from beauty salon, as well as in surface water and drinking water using HPLC coupled to a diode array detector and linear scan voltammetry. Through this study, it was possible the identification of semi-quinonediimine, quinonediimine, dimers (derived from toluenediamine), and trimer radical identified as Bandrowski's Base derivative (BBD) formed during autoxidation of PTD. Salmonella Typhimurium YG1041 assay with and without metabolic activation induced rat-liver (S9) indicated mutagenic activity for BBD. Levels of PTD were determined by the standard addition method in samples collected from the wastewater of a beauty salon, as well as from the water before and after treatment in a drinking water treatment plant (DWTP) reached concentrations of 2.08 ± 0.21, 2.36 ± 0.10 × 10−3, and 1.77 ± 0.13 × 10−3 mg L−1, respectively. In addition, linear sweep voltammetry was used to monitor the BBD found at the concentration of 1.59 ± 0.35 mg L−1 in wastewater collected from the beauty salon.

The Contribution of Heteroatoms in Amide Derivatives with an Identical Structure on Nickel Electrodeposits

Four amide derivatives, urea (U), thiourea (TU), acetamide (A), and thioacetamide (TA), all of which are based on the same molecular structure, were used as additives in the electrodeposition of nickel from ammoniacal media. The influence of the thiocarbamoyl, carbonyl, methyl, and amino groups on the nickel deposits was systematically evaluated to determine the contributions of the heteroatoms in the amide derivatives. The introduction of amino (–NH2) or thiocarbamoyl (–C=S) groups was found to potentially benefit nickel deposition. The additive TU can change the nucleation mechanism of nickel from progressive to instantaneous nucleation, and can refine the grain size of the nickel deposits. The preferred crystallographic orientation, Ni(111), did not change in the presence of any of the four additives. Nevertheless, when TU or TA was added, the Ni(200) crystal plane was suppressed and the Ni(220) crystal plane was promoted. The energies of the highest occupied molecular orbital and lowest unoccupied molecular orbital, as well as the dipole moment, were determined to characterize the molecular features of the amide derivatives, and further verified that the S atom was the most probable adsorption center. These results were beneficial for understanding the mechanisms of the additives and for facilitating the rational design of additives for metal electrodeposition.

Leaching of cuprite through NH4OH in basic systems

Abstract Cuprite is a difficult oxide to leach under acidic conditions (for the maximum extraction of 50%). In this research, the feasibility of leaching cuprite in an ammoniacal medium was studied. The working conditions addressed here were the liquid/solid ratio (120:1–400:1 mL/g), stirring speed (0–950 r/min), temperature (10–45 °C) and NH4OH concentration (0.05–0.15 mol/L). In addition, different ammoniacal reagents (NH4F and (NH4)2SO4) were analyzed. The experiments were performed in a 2 L reactor with a heating mantle and a condenser. The most important results were that the maximum leaching rate was obtained at pH 10.5, 0.10 mol/L NH4OH, 45 °C, 4 h, 850 r/min and a liquid/solid ratio of 400:1, reaching a copper extraction rate of 82%. This result was related to the non-precipitation of copper in solution by the formation of copper tetra-amine. The liquid/solid ratio and stirring speed were essential for increasing the cuprite leaching. The maximum leaching rate was achieved at higher temperatures; however, significant copper leaching rate occurred at temperatures near the freezing point of water (17.9% over 4 h). Increasing NH4OH concentration and decreasing particle size increased the cuprite leaching rate. The two ammoniacal reagents (NH4F and (NH4)2SO4) had low extraction rate of copper compared with NH4OH. The kinetic model representing cuprite leaching was a chemical reaction on the surface. The order of the reaction with respect to the NH4OH concentration was 1.8, and it was inversely proportional to the radius of the ore particles. The calculated activation energy was 44.36 kJ/mol in the temperature range of 10–45 °C.

Membrane-assisted enrichment of zinc(II) from and into ammoniacal media through non-dispersive synergistic extraction

Abstract The enrichment of zinc(II) in ammoniacal media with non-dispersive synergistic extraction (NDSX) was achieved in a sandwich-supported liquid membrane module, in which a mixed extractant containing 4-ethyl-1-phenyl-1,3-octadione (HA) and trioctylphosphine oxide (TOPO) was used as the carrier. Several parameters of Zn(II) transport, including carrier concentration, diluent type, feed pH, total ammonia concentration, and temperature, were systematically investigated. The results showed that the mixing of TOPO with HA can effectively improve the Zn(II) enrichment from and into ammoniacal solutions. The transport efficiency of zinc increases with increasing carrier concentration and temperature. Moreover, Zn(II) transport is dependent on the total ammonia concentration and solution pH of the feed phase. The nonpolar n-octane is more beneficial to zinc transport than the polar octanol. Five successive transports exhibit excellent membrane stability and the effective uphill transport of zinc from and into ammoniacal media with NDSX.

Multi-dimensional hydroxyapatite microspheres as a filling material of minicolumns for effective removal at trace level of noble and non-noble metals from aqueous solutions

In this paper, the removal of noble and non-noble metals from aqueous solutions on multi-dimensional hydroxyapatite microspheres (MD-HAp-Ms) in column experiments was studied.The efficiency of non-noble metal removal, viz. Co(II) and Ni(II) commonly presented in the environment, and the attachment mechanism onto MD-HAp-Ms readily depended on the concentration of H+ in the influent solution.In contrast, ICP-MS, SEM, XRD, TEM/EDX and RAMAN investigations independently revealed that the adsorption of Pb(II) onto the minicolumns was complete over the entire pH range and did not significantly depend on the medium acidity/basicity. The formation of a hydroxylpyromorphite phase with a general formula of Pb5-x/Cax(PO4)3OH onto the calcium MD-HAp-Ms minicolumns during Pb(II) uptake regardless from the used pH range was detected.Compared to non-noble metals, the noble ions Ag+, Pd2+, Pt2+, Au3+ formed nanoparticles with an average size of 10–50 nm during adsorption onto the MD-HAp-Ms in ammoniacal medium. The efficiency of noble ions removal was in accordance with their standard electrode potential (E0).

Reuse of sustainable materials for xylenol orange dye and copper (II) ion ammoniacal removal

Water pollution caused by heavy metals and organic compounds is an environmental problem with negative impact, making the restoration of water quality a priority. In this paper, the adsorption of xylenol orange dye (XO) on vitreous tuff mineral (VT) was studied. It was established that the adsorption capacity of VT was 45.17 mg/g. The removal was carried out by interactions between active sites on the surface of the material and the functional groups of the dye. The solid waste obtained from this process (VTXO) was reused as adsorbent material for Cu removal in the form of the complex Cu-NH3 because this process was done in an ammoniacal medium. It was found that the adsorption capacity of this new material was 33.09 mg/g. In a previous research, VT mineral was used to remove crystal violet (CV) instead of XO. The solid waste of this last process (VTCV) was also applied for Cu-NH3 removal, in order to compare the adsorption capacity of VT after the adsorption of two different kinds of dyes. The adsorption capacity of VTXO was lower than that of VTCV (71.23 mg/g). In both processes, adsorption kinetic was well described by a chemical adsorption onto a heterogeneous surface. The equilibrium time for XO removal was 50 min and 80 min for Cu-NH3. The experimental design stated that the maximum adsorption capacity was reached when the initial concentration was 6400 mg/L and the solid-liquid ratio was 10 g/L. The system that requires the least amount of adsorbent was the counter flow batch. Finally, it was possible to estimate the behavior of the system on a higher scale. This research provides an efficient and economical alternative to treat water contaminated with dyes and cooper in an ammoniacal medium using the same material in both processes, one after the other.

Direct enrichment of zinc(II) from and into ammoniacal media with commercialLIX84I

Abstract Solvent extraction of zinc(II) from and into ammoniacal media has been investigated using commercial LIX84I extractant. The effects of aqueous solution pH, total ammonia concentration and temperature on extraction of zinc(II)and ammonia stripping of loaded organic phases were examined. The extraction and stripping behaviors of zinc was also compared in the absence and presence of tributyl phosphate (TBP). The results indicate that LIX84I presents a good potential for zinc extraction in the ammonical solution. However, TBP has an antagonistic effect on zinc extraction with LIX84I. The extraction behavior of Zn(II) presents a special swing phenomenon in the both cases with and without TBP. The slope analysis and IR spectra indicate that each zinc ion can coordinate with two LIX84I molecules, whereas TBP molecules could bond with the LIX84I molecules, thus depressing zinc extraction. The zinc loaded organic phases can be effectively stripped with the ammoniacal media, especially increasing the ammonia concentration. Zinc stripping is more easy for the mixed system with TBP than the individual LIX84I system. Moreover, the extraction of zinc is an exothermic process, whereas the ammonia stripping of zinc is an endothermic process. The extraction and stripping isotherms indicate that the direct enrichment of zinc(II) from and into ammoniacal media can be achieved with the commercial LIX84I. These results are helpful for the hydrometallurgical recovery of zinc from the non-traditional resources.

Extraction-Stripping Patterns during Co-Extraction of Copper and Nickel from Ammoniacal Solutions into Emulsion Liquid Membranes Using LIX 84I®

Extraction of nickel and its co-extraction with copper from ammoniacal media into emulsion liquid membrane systems (ELMs) was investigated using LIX 84I as the carrier. Measurement of the solute stripped in the internal phase of emulsion opened a new dimension in the study of the ELM extraction processes. The effect of operating parameters such as feed pH, initial feed concentration, and treat ratio of emulsion to feed and the effect of emulsion parameters such as internal phase stripping acid concentration, carrier concentration, and internal phase volume fraction were investigated. The optimal pH for extraction was 8.1. The overall extraction process was strongly favored by the factors that lead to enhancement of uptake of metal ions such as increase in the carrier concentration and the treat ratio. Investigations on the stripping patterns in W/O emulsions revealed that sulfuric acid of 1.0 M concentration was optimal for nickel stripping in ELMs but the process was slow. Stripping of copper was relatively fast and was favored by higher acid concentrations. The amount of nickel extracted declined in the presence of copper during co-extraction of copper and nickel and the amount of copper stripped in the internal phase of the emulsion was equivalent to the amount of nickel loaded by the emulsion. In general, almost 55% of the metal loaded in the emulsion was found to get stripped in the duration of the runs. Hence, there is scope to formulate emulsions and tune other operating parameters to achieve selective separation of one of the two metals co-extracted in the internal phase of the emulsion.

The Dynamic Interfacial Understanding of Zinc Electrodeposition in Ammoniacal Media through Synchrotron Radiation Techniques

Resorted to the advanced synchrotron radiation techniques, the interfacial evolution behaviors of zinc electrodeposits from ammonium chloride media have been disclosed using ex situ X-ray absorption spectroscopy (XAS) and real-time dynamic X-ray imaging (DXI). The XAS spectra indicate that the predominant zinc(II) species in ammonium chloride media present a tetrahedral configuration independent on aqueous pH. However, the DXI results suggest that the diverse morphologies of zinc deposits are highly dependent on aqueous pH due to the change of inner coordination sphere of zinc species. Moreover, the anodic stripping of zinc deposits firstly results from the dissolution of compact deposits at the substrate side. These observations provide a deep interfacial insight on zinc electrodeposition in ammonium chloride media, thereby allowing the morphologies of metal electrodeposits to be better regulated through the change of solution chemistry.

Inhibiting Mossy Zinc Electrodeposits from Ammoniacal Media with Hydrophobic Tetraalkyammonium Salts

The effect of tetraalkyammonium chlorides (TAACs) with different numbers of long alkyl chain (-C8H17) on zinc electrodeposits in the ammoniacal media was systematically investigated by voltammetric measurements, scanning electron microscopy and X-ray diffraction. It was found that the inhibition effect of TAACs on mossy zinc deposits increases with increasing their hydrophobicity. The hydrophobic TAACs can improve the smoothness and crystallinity of zinc deposits and change the most preferred orientation. Meanwhile, the inhibition effect of hydrophilic octyltrimethylammonium chloride (OTAC) on mossy zinc deposits can be enhanced with increase of OTAC concentration. The improvement on the smoothness of zinc deposits with hydrophobic methyltrioctylammonium chloride (TOAC) is dependent on the pH of electrolyte. The presence of saturated TOAC at pH 7.5 can produce better zinc deposits with higher smoothness. The inhibition mechanism of both hydrophilic and hydrophobic TAACs on mossy zinc deposits has been elucidated. These results will allow the morphology of metal deposits to be better controlled by the specific organic additives.

Ultrasound assisted formation of reduced graphene oxide-copper (II) oxide nanocomposite for energy storage applications

The present exploration emphasizes on facile, one-pot sonochemical technique to fabricate reduced graphene oxide-Copper(II)oxide (rGO-CuO) nanocomposite where optimum amounts of CuO and functionalized-graphene phases synergistically establish superior electrochemical signature. Ultrasound assisted reduction of graphene oxide (GO) in presence of Cu(II) ions in ammoniacal medium followed by in-situ deposition of self-assembled CuO on rGO layers gives rise to the resultant rGO-CuO nanocomposite. The as-synthesized sample on spectroscopic, microscopic, surface and thermal analyses revealed stable, nanostructure morphology with large surface area opening the scope for its supercapacitive applications. The electrochemical performances investigated by cyclic voltammetry and chronopotentiometric charging/discharging cycles at a current density of 1Ag−1 in the potential window of −0.3V to +0.8V in 0.5M Na2SO4 aqueous medium, display appreciable specific capacitance (Cs=227Fg−1) of rGO-CuO nanocomposite compared to the reduced graphene oxide (rGO) (136.4Fg−1) and blank-copper oxide (30.1Fg−1) synthesized, and experimented under similar conditions. In aid executed electrochemical impedance spectroscopy for rGO-CuO nanocomposite suggests supercapacitive behavior with better electrical conductivity and ion transport performances assuring it a promising electrode material for future energy storage devices.

In situ NH2-functionalized graphene oxide/SiO2 composites to improve Cu(II) removal from ammoniacal solutions

A special adsorption manifestation for Cu(II) removal from ammoniacal solutions was elucidated. In this process, the graphene oxide/SiO2 composites (GO/SiO2) were prepared by a facile method, and the amino groups were successfully grafted on the surface of GO/SiO2 through an in situ functionalized reaction in the ammoniacal media. The composites were thoroughly characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman and X-ray photoelectron (XPS) spectroscopies. The spectral analyses proved that the amino groups can be in situ generated through the reaction between ammonia molecules and functional groups on the surface of composites. The results indicate that the NH2-functionalized GO/SiO2 composites are beneficial for the adsorption of Cu(II) due to the special affinity of amino groups with Cu(II). The effects of solution pH, mass percentage of GO in composites and temperature have been discussed by batch adsorption experiments. The experimental data can be well fitted with the pseudo-second order kinetics and Freundlich isotherm models. The maximum adsorption capacity of Cu(II) is 158.9mgg−1 at equilibrium conditions. In addition, thermodynamics study confirmed the endothermic nature of Cu(II) adsorption, and the adsorption mechanism was discussed. Hence, the GO/SiO2 composites have great potential for the efficient removal of Cu(II) from ammoniacal solutions.

Insights into coextraction of water and ammonia with nickel(II) through structural investigation

The coordination structures of the nickel(II) complexes of 4-ethyl-a-pheneyl-1,3-octadione (denotes A) formed upon solvent extraction from ammoniacal media have been investigated. The combination analysis of their X-ray absorption spectroscopy with IR, UV–Vis and NMR spectroscopies provides a molecular-level understanding on the coextraction behavior of both water and ammonia molecules during nickel extraction. XANES spectra not only verify that the nickel extracts with octahedral configuration are independent on aqueous pH of ammoniacal solutions; and also demonstrates the structures are independent of the nickel complexes being solid or in solution. The structural investigation and elemental analysis of solid nickel extract indicate that both water and ammonia molecules can simultaneously coordinate with nickel extract to form a hexa-coordination complex of NiA2·H2O·NH3. The structural parameters of nickel extracts were extracted by EXAFS fitting. The mean Ni–Oeq bond length of nickel chelate rings is 2.00Å, and the mean Ni–O/Nax bond length of axially coordinated water and ammonia is 2.09Å.