NH4OH Concentration Research Articles

Sustainable separation of molybdenum from mixed mineral acids generated as semiconductor industry waste streams using tributyl phosphate (TBP) by effects of hybrid machine learning models

This study explores the separation and optimization of molybdenum (Mo) from mixed mineral acids derived from semiconductor industry waste streams with tributyl phosphate (TBP) by implementing machine learning (ML) models. Considerable experimental tests were performed to evaluate the impact of various operational variables on the effectiveness of Mo extraction and stripping. The support vector regression (SVR) paired with harmony search algorithm (HSA), genetic algorithm (GA), and shuffled frog leaping algorithm (SFLA) were employed for enhancement in the separation process and structural optimization. The SVR-SFLA model yielded the most meticulous predictions, identifying optimal extraction conditions with a TBP concentration, mixing time, temperature, and O/A ratio of 50%, 30 min, 25 °C, and 1, respectively, achieving 77.8% efficiency. The derived results from the SVR-SFLA model, in tandem with the McCabe-Theil diagram, indicated a four-stage counter-current extraction process required to achieve a yield exceeding 99%. For the stripping process, the hybrid model indicated optimal conditions with 3 M NH4OH and an A/O ratio of 0.5 at 50 °C for 20 min, requiring two counter-current stages for nearly complete stripping. Feature importance analysis using a random forest algorithm (RFA) highlighted the NH4OH concentration and phase ratio as the most significant factors, contributing 40.3% and 29.1%, respectively, to the stripping from the loaded TBP phase. The final product, obtained after crystallization and thermal decomposition of the strip solutions, was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), revealing 99.74% purity for molybdenum trioxide.

Understanding the growth kinetics of polydopamine nanoparticles as a function of the temperature and the type of alcohol used as solvent media in their polymerization

Currently, one of the bottlenecks in the large-scale production of particles used for biomedical purposes is reproducibility achieving sizes less than 100 nm. For this reason, the main purpose of this work was to elucidate how the size of polydopamine nanoparticles (PDA NPs), which are widely used in cancer nanomedicine, was affected by several synthesis parameters to facilitate their production scaling-up. Specifically, PDA NPs growth kinetics were investigated as a function of the polymerization temperature (15–50 °C) and the type of alcohol (ethanol, 2-propanol, or a mixture of both) used to produce them, finding that an increase in temperature and the amount of 2-propanol in the solvent media allowed smaller NPs to be obtained. Based on the results achieved, a mathematical model capable of predicting PDA NP diameter as a function of the temperature and reaction time, the NH4OH concentration, and the type of alcohol used to synthesize them was proposed. Also, PDA solubility in the different media was studied to explain NP size behavior depending on the type of alcohol employed, which conditioned the formation of PDA oligomers. Finally, additional assays were conducted to confirm that an increase in the synthesis temperature did not affect some of the most important properties of PDA NPs from a biomedical point of view: their Fe3+-loading capacity and their inherent antitumor activity. Therefore, the results obtained in this research could be useful to scale-up the obtaining of 100 nm PDA NPs in a reproducible manner hereafter without significantly altering their outstanding physical-chemical properties.

Influence of ionic liquid (R4PSCN) for selective separation and recovery of copper from spent Cu[sbnd]Cr catalyst leach liquor

Separation and recovery of copper (Cu) from sulphate mediated CuCr spent catalyst leach solution through solvent extraction approach has been systematically investigated. A number of Ionic Liquid (IL) and other conventional extractants were used while investigating the selectivity and efficient extraction tendency of either IL or extractants towards Cu(II). In context of copper extraction efficiency, the adopted organic reagents followed the descending order: R4PSCN > R4PD > R4PCy > Cyphos 101 > Aliquot 336 > D2EHPA > Cyanex 272. The extraction behavior of Cu(II) was established based on slope analysis method. From the results it was noticed that extraction occurs through a cation exchange mechanism with association of a mole of Cu(II) per mole of R4PSCN. The plot of log D vs. log [R4PSCN] yield a linear relationship with a slope close to 4 which is used to propose extraction reaction mechanism/ stoichiometry. The nature of complex between Cu(II) and IL was further examined using FTIR analysis of the loaded organic phase with the diluent. Mc-Cabe Thiele diagram was constructed to predict quantitative extraction of Cu(II) which revealed the need for two stages at aqueous to organic (A:O) phase volume ratio of =3:1. The stripping isotherm constructed at optimum NH4OH concentration (0.4 M) suggests the need for two stages at O:A phase volume ratio of = 2:1 for complete stripping of copper with regeneration of R4SCN for further use. Both isotherm conditions were validated by 6 cycles of counter current simulation (CCS) study for obtaining the desired amount of Cu(II) loaded R4SCN (during extraction) and/or stripped copper solution (during stripping). Overall copper enrichment was ∼6 fold leading to produce a copper(II) solution of 48 g/L from 6 g/L Cu(II). The stripped solution was subjected to crystallization study to produce copper sulphate crystals of high purity and was confirmed by XRD analysis of crystal phases.

A comparative study on the production of Ni1/3Co1/3Mn1/3C2O4 cathode precursor material for lithium-ion batteries using batch and slug-flow reactors

The intermittent nature of the renewable energy sources drifts research interest towards various electrochemical energy storage devices, such as the lithium ion battery, which offers consistent power supply. The manufacturing cost and electrochemical performance of a battery pack largely depends on the quality of the cathode material, which further depends on the production method and its parameters. However, the traditional stirred tank-based co-precipitation manufacturing process for precursors of lithium nickel manganese cobalt oxide (NCM111) cathode suffers from inhomogeneity in the reaction environment, which leads to non-uniform morphology and particle size distribution (PSD). In this work, slug-flow-based manufacturing platform, which offers a homogeneous reaction environment, is used for the continuous production of NCM111 oxalate precursors. One of the novel features of this work is the comparative study between the quality of batch and slug-flow-derived products. The slug-flow-derived product is found to be better in terms of having bigger particle size, narrower PSD and higher tap density. The study on the single and dual-element precipitation in similar conditions to understand the co-precipitation behavior in the slug-flow manufacturing platform is also a unique feature of this work. Furthermore, the effect of NH4OH concentration and residence time (RT) on the electrochemical performance of cathode were also studied and it is found that the cathode precursors synthesized at a NH4OH concentration of 0.08 M and a RT of 2 minutes followed by lithiation shows a better electrochemical performance of 128 mAh g−1 at 0.1 C with cycling stability of more than 80% both at 0.5 C and 1 C.

Application of Fe3O4/thiamine Magnetic Particles in the Removal of Methylene Blue

Fe3O4/thiamine particles were prepared in this work via precipitation method. The synthesis method is based on the principle of precipitation of Fe3O4 particles in the presence of thiamine coating agent. Also, the potential application of Fe3O4/ thiamine in the removal of methylene blue (MB) was investigated. Several factors that affect the synthesis of Fe3O4/thiamine such as base concentration, mass ratio of FeCl2 to thiamine, reaction temperature, and reaction time were determined. Optimal conditions for preparing Fe3O4/thiamine are NH4OH concentration = 10%, mass ratio of FeCl2:thiamine = 5:1 (g g-1), reaction temperature = 30 °C, reaction time = 120 min. The average particle size of Fe3O4/thiamine is 293.7 nm while the specific surface area, pore diameter, and magnetization of the obtained Fe3O4/ thiamine particles are 57 m2 g-1, 192.67 Å, and 2.4 emu g-1, respectively. The interesting point of this work is to obtain the Fe3O4/thiamine at low temperature with less amount of NH4OH used. Furthermore, 79.08% of MB could be removed using Fe3O4/thiamine as an adsorbent, with a maximum adsorption capacity of 31.63 mg g-1 at pH of 10, a MB concentration of 50 mg L-1, and an adsorption time of 15 min. Adsorption kinetics studies showed that the pseudo-second-order model fitted the experimental data better than the pseudo-first-order and the adsorption process is physical adsorption following the Freundlich adsorption isotherm model. An adsorption mechanism of MB onto Fe3O4/thiamine was also suggested. The synthesized Fe3O4/ thiamine particles could be a potential material for treating wastewater.

Thermochemical modification of beech wood with ammonium hydroxide

Four variants of the thermochemical modification were conducted on beech wood at a temperature of 130 °C, employing NH4OH concentrations of 5% or 10% for durations of either 12 or 24 h. The weight% gain (WPG) and bulking coefficient (BC) were initially calculated. Subsequently, the wood’s degree of discoloration was assessed using the CIELAB-colour-system. Chemical structure alterations were determined through Fourier transform infrared spectroscopy (FTIR), while the compressive strength of the wood parallel to the grain was measured. As the NH4OH concentration increased and the treatment duration extended, the samples displayed simultaneous weight increase and volume reduction. The ΔE* values of the samples ranged from 19.33 to 21.09 units, indicating significant color alteration. FTIR analysis revealed differences between the spectra of the unmodified control sample and the NH4OH-treated samples. The modification reduced in hydroxyl and carboxyl groups within the main and side chains of hemicelluloses. Additionally, a decrease in the absorption peak intensity of the unconjugated carbonyl group at 1740 cm− 1 indicated a relative reduction in hemicellulose content. Compressive strength tests showed that the thermochemical modification improved the modulus of elasticity, increasing it from 10,898 MPa (in the control sample) to a range of 11,663 − 13,390 MPa. Similarly, the compressive strength increased from 77.10 MPa to 81.56-107.19 MPa. Interestingly, this improvement was more pronounced with higher concentrations of NH4OH and prolonged modification durations.

Optimization of Soybean Protein Extraction with Ammonium Hydroxide (NH4OH) Using Response Surface Methodology.

Plants have been recognized as renewable and sustainable sources of proteins. However, plant protein extraction is challenged by the plant's recalcitrant cell wall. The conventional extraction methods make use of non-reusable strong alkali chemicals in protein-denaturing extraction conditions. In this study, soy protein was extracted using NH4OH, a weak, recoverable, and reusable alkali. The extraction conditions were optimized using response surface methodology (RSM). A central composite design (CCD) with four independent variables: temperature (25, 40, 55, 70, and 85 °C); NH4OH concentration (0.5, 1, and 1.5%); extraction time (6, 12, 18, and 24 h) and solvent ratio (1:5, 1:10, 1:15 and 1:20 w/v) were used to study the response variables (protein yield and amine concentration). Amine concentration indicates the extent of protein hydrolysis. The RSM model equation for the independent and response variables was computed and used to create the contour plots. A predicted yield of 64.89% protein and 0.19 mM amine revealed a multiple R-squared value of 0.83 and 0.78, respectively. The optimum conditions to obtain the maximum protein yield (65.66%) with the least amine concentration (0.14 Mm) were obtained with 0.5% NH4OH concentration, 12 h extraction time, and a 1:10 (w/v) solvent ratio at 52.5 °C. The findings suggest that NH4OH is suitable to extract soybean protein with little or no impact on protein denaturation.

A Combined Approach for the Treatment of Textile Dye Bath Effluent Using CO2 Gas

In this study, baking soda extraction from textile dye bath effluent has been investigated. The novel notion of employing amino acid additions to improve the standard Solvay method and thereby boost the efficiency of Na+ recovery has been investigated. Glycine, L-arginine, and L-alanine are three amino acid additions examined for their effect on enhancing Na+ recovery, and the best-suited additive is chosen. The dumping of brackish dye bath effluent, which has a high percentage of sodium chloride, causes textile dye baths from the textile industry. The primary goal was to remove Na+ (sodium) from the effluent using carbon dioxide gas, which has environmental benefits. Carbon dioxide (CO2) is the most common greenhouse gas, trapping heat and raising global temperatures, therefore contributing to climate change. The Solvay process is used to transform Na+ in salty wastewater into a valuable product. The effect of different operating variables such as NH4OH (ammonium hydroxide) concentration, reaction temperature, carbonation time, and carbon dioxide gas flow rate on bicarbonate production was investigated. Maximum sodium recovery of about 68 percent is attained under optimal circumstances. When compared with the regular Solvay process, the modified Solvay method has a greater recovery efficiency (33 percent). Amino acid addition (arginine) improved conversion efficiency while also lowering the process’s ammonia need.

A "turn-off" photoluminescent sensor for H2O2 detection based on a zinc oxide-graphene quantum dot (ZnO-GQD) nanocomposite and the role of amine in the development of GQD.

In this work, graphene quantum dots (GQD) were prepared through a hydrothermal process. The photoluminescence (PL) emission spectrum for GQD prepared with high NH4OH concentration (sample D1-t) was attained at lower wavelength (406 nm), compared to GQD synthesized with low NH4OH concentration (sample D2-t attained at 418 nm). From these results, a smaller particle size for D1-t was deduced; according to TEM images the GQD particles are around 5 nm. The Raman ID3/IG ratio which is related to C-O groups at the edges of GQD and the full width at half maximum was lower for D1-t than D2-t. This was ascribed to the amine group incorporation at the edges and at the basal planes in D1-t, whilst in D2-t they prefer principally the edges of the GQD structure. The ZnO nanoparticles bonded to GQD (ZnO-GQD, nanocomposites) enhance the PL emission intensity. The H2O2 detection tested by photoluminescence spectroscopy, was found to occur thanks to the ZnO from the nanocomposite and its interaction with H2O2, producing a quenching effect. This quenching was accentuated by the increase of the H2O2 concentration. Such properties suggest the ZnO-GQD nanocomposite as a candidate to be used as a sensor material.

Microdroplet-based synthesis of polymethylsilsesquioxane microspheres with controllable size, surface morphology, and internal structure

Monodispersed polysilsesquioxane (PSQ) microspheres are generally synthesized by the classical sol–gel method. Using this method, the particle size is limited to the range of several hundred nanometers to several microns. The preparation of monodispersed large-sized PSQ microspheres remains technically challenging. Herein, with the polymethylsilsesquioxane (PMSQ) microspheres as the model product, a microdroplet-based strategy was developed for the synthesis of PSQ microspheres with larger particle sizes. According to the properties of the reactants, a W/O microdroplet reaction system was realized, i.e., with the mixture of methyltrimethoxysilane (MTMS) and liquid paraffin as the continuous phase and ammonia solution as the dispersed phase. The monodispersed W/O microdroplets were generated in a step T-junction microfluidic device, and solidified into PMSQ microspheres via in-situ interfacial polycondensation (∼2 min) in a microtube reactor. The size, surface morphology and internal structure of the PMSQ microspheres could be tuned by adjusting the synthesis conditions, mainly including the two-phase flow rates, MTMS concentration, NH4OH concentration, and the structural parameters of the microfluidic device. Various PMSQ microspheres with corrugated or smooth surface morphology, and loose or dense internal structure could be synthesized. The microsphere size could be tuned from tens of microns (∼20 μm) to hundreds of microns.

Via resistance increase accelerated by thermal stress

The resistance between an aluminum (Al) metal line and a tungsten (W) via increased after thermal stress. In the wafer processing, the post W chemical mechanical planarization (WCMP) cleaning left residual WO3 on the W plug. Since the resistivity of WO3 is low, the interfacial resistance was low and escaped the first electrical detection. However, the WO3 was spontaneously reduced by the Ti of the overlaying metal line, through which TiO2 formed. The reduction was accelerated by a thermal stress. Compared with WO3, TiO2 has a more negative formation enthalpy, and the valence electrons of Ti are more tightly bound to the O ion cores. As a result, the resistivity of TiO2 is higher than that of WO3. In addition, there was Al diffusing through TiN to reduce the oxides of both Ti and W. The product Al2O3 is thermodynamically the most stable, and the most resistive amongst the oxides of the three metals. Meanwhile, due to its superhydrophilicity, the residual WO3 had retained liquid that contained hydrofluoric acid (HF) used for the post WCMP cleaning. The HF corroded the Ti glue layers of both the via sidewall and the overlaying metal line. The dry etch of the metal line exposed the Ti-corroded volume of the metal line to the deionized (DI) water for the post metal-etch cleaning. The DI water oxidized the Ti on the W plug. The W/TiN interface on the W plug was also subjected to enhanced mechanical stress which led to voids along the interface. All these factors had caused an increase of the via resistance which eventually became high enough to be detected. The fix employed was to increase the NH4OH concentration to more effectively remove the residual WO3. The thermal stress implemented in the fab therefore had prevented the residual WO3 from developing into a costly field failure.

Altering NH4OH concentration in producing chemical bath deposited CdS to steadily support electrodeposited CdTe

Development of chemical bath deposited (CBD) CdS to steadily support the electrodeposited (ED) CdTe, by changing the volume of NH4OH, a pH adjuster, in the CBD bath is reported here. The optimal volume of NH4OH, which is the controlling parameter of interest, was identified based on the optical, electrical, structural, and morphological properties of the CdS developed. The sample developed exhibits the band gap energy of 2.32 eV with light transmittance >80% (500–900 nm). The photo-electrochemical cell and Mott-Schottky studies revealed n-type conductivity, open circuit voltage (VOC) of 0.529 V, and short circuit current density (JSC) of 12.290 μA/cm2 at the CdS/electrolyte junction while the X-ray diffraction data and phase analysis revealed the formation of a blended hexagonal/cubic structures. Further, the scanning electron microscopic and the energy-dispersive X-ray spectroscopic studies elucidated a well-compact grain arrangement and agreed with the theoretical chemical composition (1:1) of CdS respectively.

APPLICATION OF DIELECTRIC BARRIER DISCHARGE AND PLASMA-CHEMICAL REACTOR FOR WATER PURIFICATION FROM NH4OH

Water purification from ammonium hydroxide was carried out by using two methods of processing: treatment with ozone generated by a dielectric barrier discharge (DBD) as well as processing in plasma-chemical reactor equipped with a water electrode and a diaphragm, where the main oxidation factors were OH hydroxyl radicals. The volume of the treated aqueous solution was 300 ml and the NH4OH concentration was 0.025 ml in both cases. The phenolphthalein test was used for visual analysis of the content of an aqueous solution of ammonia in water. The ozone concentration was about 5.8 mg/l in water with ozone injection from an ozone generator and 0.7 mg/l in a plasma-chemical reactor, respectively. The analysis of OH and NO radicals in the water-air gap of the plasmachemical reactor was carried out using a spectrometer operated in the range of 200...800 nm.

Density-Dependent Carrier Recombination in MoS2 Quantum Dots and Its Implications for Luminescence Sensing of Ammonium Hydroxide

Zero-dimensional molybdenum disulfide (MoS2) quantum dots (QDs) have attracted remarkable interest due to their peculiar properties such as the quantum-confinement effect and high surface area. Exploring recombination dynamics in MoS2 QDs is not only expected to gain a deeper insight into their fundamental physics, it is also important for potential applications in optoelectronics and energy-conversion technology. This study synthesized p-type MoS2 QDs doped with diethylenetriamine (DETA) using pulsed laser ablation method. A hole concentration as high as 2.08 × 1012 cm–2 has been demonstrated by gate-dependent conductance measurements. A 110-fold enhancement of photoluminescence in the p-type MoS2 QDs has been found after the introduction of DETA, and the dependence of the radiative and nonradiative recombination of MoS2 QDs on carrier densities were studied. As the carrier density was increased, a decrease of the radiative lifetime was found, which is similar to the behavior of the radiative lifetime in monolayer MoS2. The Shockley-Read-Hall (SRH) and Auger recombination dominates the nonradiative recombination at low and high carrier densities, respectively. The SRH lifetime of MoS2 QDs increases with the increased carrier density, suggesting that the recombination mechanism at the low carrier density is dominated by the SRH recombination. This study found that as the carrier densities exceeded 0.53 × 1012 cm–2, the Auger recombination was responsible for the reduction of PL. Furthermore, MoS2 QDs was used as a fluorescent sensor for the detection of ammonium hydroxide (NH4OH). The PL intensity of MoS2 QDs demonstrates a gradual decrease with increasing NH4OH concentration. By investigating the time-resolved PL (TRPL), the mechanism that leads to the decrease of PL in MoS2 QDs is addressed. This investigation is expected to demonstrate a promising development of an effective and low-cost MoS2 QDs-based fluorescent sensor with superior sensitivity for the rapid detection of ammonia in aqueous media.

Electrical Conductivity of Tungsten-Containing Ammonia Solutions and Calculation of Its Activation Energy

Abstract—The activation energy of the electrical conductivity of ammonium hydroxide–tungstate ion solutions is determined in the NH4OH concentration ranges 0.01–6 and 0.01–0.2 mol/L (based on the metal). For all solutions, the activation energy decreases substantially with increasing temperature and decreases insignificantly with increasing tungsten content in a solution at a constant ammonium hydroxide concentration. An increase in the NH4OH concentration at a constant tungsten content in a solution is found to cause an increase in the activation energy. All calculated activation energies suggest that the charge transfer in the system under study is determined by diffusional restraints.

Electrical Conductivity of Tungsten-Containing Ammonium Hydroxide Solutions

The electrical conductivity of ammonium hydroxide–tungstate ion solutions is studied in the concentration range 0.01–6 M NH4OH and 0.01–0.2 M W (based on metal) as a function of the reagent content in a solution and its temperature. The electrical conductivity of the system is shown to increase linearly as the tungsten content in the solution increases, and an increase in the electrical conductivity with the NH4OH concentration is not linear. The electrical conductivity of the system is found to increase linearly as the solution temperature increases, which enables linearization of the obtained dependences and calculation of the temperature coefficients of the electrical conductivity of the solutions in the aforementioned range of the reagent concentrations.

Mechanism and Kinetics of Malachite Dissolution in an NH4OH System

Copper oxide minerals composed of carbonates consume high quantities of leaching reagent. The present research proposes an alternative procedure for malachite leaching (Cu2CO3(OH)2) through the use of only compound, ammonium hydroxide (NH4OH). Preliminary studies were also carried out for the dissolution of malachite in an acid system. The variables evaluated were solution pH, stirring rate, temperature, NH4OH concentration, particle size, solid/liquid ratio and different ammonium reagents. The experiments were carried out in a stirred batch system with controlled temperatures and stirring rates. For the acid dissolution system, sulfuric acid consumption reached excessive values (986 kg H2SO4/ton of malachite), invalidating the dissolution in these common systems. On the other hand, for the ammoniacal system, there was no acid consumption and the results show that copper recovery was very high, reaching values of 84.1% for a concentration of 0.2 mol/dm3 of NH4OH and an experiment time of 7200 s. The theoretical/thermodynamic calculations indicate that the solution pH was a significant factor in maintaining the copper soluble as Cu(NH3)42+. This was validated by the experimental results and solid analysis by X-ray diffraction (XRD), from which the reaction mechanisms were obtained. A heterogeneous kinetic model was obtained from the diffusion model in a porous layer for particles that begin the reaction as nonporous but which become porous during the reaction as the original solid splits and cracks to form a highly porous structure. The reaction order for the NH4OH concentration was 3.2 and was inversely proportional to the square of the initial radius of the particle. The activation energy was calculated at 36.1 kJ/mol in the temperature range of 278 to 313 K.

Ammoniacal System Mechanisms for Leaching Copper from Converter Slag

In pyrometallurgical processes refining copper, the main source of loss in the conversion stage is from slag. This paper reports on research work treating converter slag containing high percentages of copper (36 wt%) using ammonium hydroxide at room temperature. Variables analyzed are solution pH, agitation, temperature, NH4OH concentration and particle size. Results showed that the hydronium ion resulting from ammonium hydroxide dissociation was the main oxidant of copper compounds in slag, such as CuO, Cu2O and Cu, with the exception of CuFeO2. The particles contain a large amount of microcracks (porosity) in their refractory structure (analyzed by compositional image capture (BSE)). Thus, the diffusion of the leaching solution through the microcracks making contact with the copper oxides would be allowed. Leaching mechanisms were corroborated by X-ray diffraction and scanning electron microscopy analysis. Increasing temperature and NH4OH concentration while decreasing particle size obtained higher copper recoveries, reaching values of 84.8%. Under the same conditions, the main impurity (iron) was minimal (<2%). Solution pH also affected slag leaching. Agitation of the solution positively affected the rate of copper extraction. Leaching kinetics of the leaching solution through the porosity formed in the slag was analyzed under the intraparticle diffusion model. The reaction order was 1.2 with respect to the concentration of ammonium hydroxide and the model was inversely proportional to the square of the particle radius. The activation energy obtained was 42.3 kJ/mol for temperature range 283 to 333 K.

Synthesis and Photocatalytic Activity of Cu2O Microspheres upon Methyl Orange Degradation

Cuprous oxide (Cu2O) microspheres were synthesized through a simple chemical method by using ascorbic acid (AA) as reducing agent at room temperature and short reaction time. The influence of the reducing agent and ammonium hydroxide (NH4OH), as well as reaction time, on the morphology, size, and crystalline phase structure of Cu2O were explored. The obtained materials were characterized by X-ray diffraction, scanning electron microscopy, nitrogen physisorption, and temperature-programmed reduction, whereas the catalytic activity was assessed using the photodegradation of methyl orange (MO). It was found that AA was responsible for the Cu2O nanoparticles self-assembling into Cu2O microspheres after 0.16 h of reaction time. Quantum theoretical calculations revealed that self-assembly is due to the hydrophilic modification of the Cu2O-nanoparticles driven by the parallel-to-surface dehydroascorbic acid chemisorption; likewise, the simulation of a mesoscopic molecular dynamics confirmed that the amphiphilic-like nature of the dehydroascorbic acid-Cu2O complexes leads to nanoparticles’ spherical morphology. The NH4OH concentration affected the porosity and crystalline phase of the microspheres. The porous Cu2O microspheres modified into well-defined Cu0 polyhedrons with the reaction time. The Cu2O microspheres exhibited high photocatalytic activity up to 76% during decolorization of MO. Two catalytic processes were distinguished: the removal of organic compound controlled by the faceting of the particles under dark conditions, and its photodegradation using visible light increased by the porosity of the Cu2O microspheres.

Extraction of Molybdenum (VI) and Vanadium (V) from Nitrate Solutions Using Coupling of Acid and Solvating Extractants (RESEARCH NOTE)

In this study, solvent extraction method has been utilized for separation of molybdenum and vanadium from nitrate solution by utilizing coupling of acid and solvating extractants (D2EHPA and TBP extractants). The outcomes demonstrated that synergistic solvent extraction improves stability of formatted complexes for transfer to the organic phase. The main parameters such as pH value, concentration of extractants, NH4OH concentration as the stripping agent and contact time were optimized at 0.4, 15% (v/v) D2EHPA, 10% (v/v) TBP, 2 M and 30 min, respectively. The maximum separation factor of 24.84 was obtained with a new synergistic mixture of D2EHPA and TBP diluted with kerosene. According to McCabe-Thiel diagram, more than 99% of the Mo (VI) was obtained in counter current procedure and three stage numbers using 15% (v/v) D2EHPA and its mixture with 10% (v/v) TBP in kerosene, initial aqueous pH value equal to 0.4 and A/O ratio of 4/1 at room temperature for 30 min. In addition, stripping of Mo (VI) reached 98.75% in three counter current stages using 2 M NH4OH as stripping agent and A/O ratio of 1/4 for 30 min.