Mixture Of HCl Research Articles

Kinetics of Iron Collector Leaching in HCl and HF Media

Automotive catalysts containing Platinum Group Metals (PGMs) are valuable secondary raw materials for refineries. Hydrometallurgical processing of catalysts is ineffective due to the low PGMs content—0.15–0.3%. Therefore, such raw materials are melted into an iron collector containing 1.5–5% PGMs. However, when leaching a collector containing 10–20% Si in both HCl and H2SO4, the recovery of PGMs does not exceed 40%. The latter indicates incomplete destroying of the PGM-encapsulating ferrosilicon matrix. To completely destroy the ferrosilicon matrix, it is proposed to carry out the leaching process in a mixture of HCl and HF. In this case, the extraction of Fe into solution and Si into the gas phase (in the form of SiF4) exceeds 90%. This should be sufficient to completely destroy the ferrosilicon matrix and release PGMs. The current work presents the results of studies of the leaching kinetics of the iron collector containing ferrosilicon in a mixture of HCl and HF using the Shrinking Core Model (SCM). It was found that the greatest positive effect on Fe extraction into solution is exerted by HCl concentration and temperature, while Si release into the gas phase is only influenced by HF concentration. In addition, during the destroying of ferrosilicon, FeF2 is formed and deposited on the surface of the material in the form of thin-film conglomerates. This leads to diffusion difficulties and a gradual decrease in the intensity of the iron collector leaching 30 min after the start of process. After 120 min, there may be a decrease in Fe recovery into solution.

Sample preservation methods for nitrous oxide concentration and isotope ratio measurements in aquatic environments

AbstractThe nitrogen (N) and oxygen (O) stable isotope analysis of dissolved nitrous oxide (N2O) can provide important constraints on the sources and cycling of N2O in aquatic environments. The isotopic composition of aqueous N2O, both in field (natural abundance) or experimental (15N‐labeling) samples, however, may be altered by abiotic reactions involving nitrite () or hydroxylamine (NH2OH) and microbial activity during sample storage, if samples are not adequately preserved. Here we tested five different preservatives, mercuric chloride (HgCl2), copper sulfate (CuSO4), zinc chloride (ZnCl2), hydrochloric acid (HCl) mixed with sulfamic acid (SFA), and sodium hydroxide (NaOH), for fixing natural water samples from an estuary and a lake with different concentrations over a range of different storage times for N2O analyses. ZnCl2 and CuSO4 decreased the pH, and led to abiotic N2O production from , shifting the N2O isotopic composition significantly. Removal of with a mixture of SFA and HCl did not always prevent the alteration of the original N and O isotope composition of N2O, confirming the requirement for complete removal, and underscoring the biasing effects of at very low pH, even at trace levels. At low background, HgCl2 preservation led to robust and accurate results. However, in light of its toxicity and bioaccumulation potential in food webs, this fixative should be avoided. The addition of NaOH reduced abiotic side reactions involving , and yielded the most reliable and reproducible results for N2O concentration and isotope ratio measurements across tested settings and storage times.

Fast and Greener Ultrasound-Assisted Acid Extraction for the Determination of Potentially Toxic Elements in Fluorescent Lamp Waste Using ICP OES.

Understanding the chemical composition of fluorescent lamp residue, particularly potentially toxic elements is crucial for reducing environmental impacts and human health risks after disposal. However, the challenge lies in effectively analyzing these heterogeneous solid samples. Techniques involving quantitative dissolution become imperative, playing a fundamental role in quantifying trace elements. The aim of this work is to develop and present a new, faster, and more efficient and environmentally friendly method using ultrasound-assisted acid extraction to quantify potentially toxic elements (Cu, Mn, Ni, Sr, and Zn) present in fluorescent lamp waste using the inductively coupled plasma optical emission spectrometry technique. An ultrasound-assisted acid extraction method for the quantification of potentially toxic elements in fluorescent lamp waste was developed and applied as a greener alternative to conventional digestion methods. For variables optimization a full factorial design with two levels and two variables (time and temperature) was used to found which factors significantly affect the observed response. The results obtained for the developed extraction method were compared with a reference method employing a heating acid digestion (mixture of HCl, HClO4 and HF) using statistical tools. The best results were obtained using extraction time of 10 min and temperature of 25 °C. Inductively coupled plasma optical emission spectrometry was applied for element quantification. The proposed extraction method showed good results for Cu, Mn, Ni, Sr and Zn. Furthermore, the proposed method based on ultrasound radiation presents additional criteria that align with the concepts of the green analytical chemistry. A greener alternative method for determination of Cu, Mn, Ni, Sr and Zn in fluorescent lamp waste was developed. Optimal conditions for ultrasound extraction of potentially toxic elements were achieved in 10 min at temperature of 25 °C. Environmentally friendly aspects of ultrasound align with the requirements of green analytical chemistry.

Separation trace amounts of copper ion by solid-phase extraction with carbon-based sorbent prior to flame atomic absorption spectrometry

ABSTRACT In this research, a carbon adsorbent modified with curcumin ligand was utilised in the solid-phase extraction procedure. This method was coupled with flame atomic absorption spectrometry to pre-concentrate and separate trace amounts of copper ions in aqueous solutions. Different experimental parameters, including pH, eluent type and concentration, adsorbent dose, extraction time and sample volume, were studied and optimised. The obtained optimum conditions for the proposed method were: pH of solution, 4.8; extraction time, 9 min; adsorbent dose, 0.01 g; type and concentration of eluent, 1:1 mixture of HCl and HNO3 0.5 mol L−1. Under optimal conditions, the pre-concentration factor of 400.0 and linear range values of the method were 0.031–1.875 µg/L and 12.5–750 µg/L for copper ions in the initial and final solutions, respectively. The relative standard deviation (RSD) for seven replicate detections of 0.05 µg L−1 of copper ion in initial solution was calculated as 2.2%. Furthermore, the detection limit of 0.008 µg L−1 was determined for the suggested method. In order to investigate the selectivity of modified carbon adsorbent, the influence of some interfering ions on the extraction and recovery of Cu (II) was studied. Finally, the present method was employed for the determination of copper ions in real water samples and standard alloys.

Enhancement of titanium surfaces using different acid solutions at room temperature to improve bone cell responses

Background/purposeEarly osseointegration of titanium (Ti) dental implants relies on the surface topography. Surface modification of Ti seeks to enhance bone regeneration around implants. Acid etching is the simple, less technique sensitive and cost-effective technique for surface treatment. The purpose of this study was to elucidate the simplified acid etching technique at room temperature lies in its capacity to enhance both physical properties and biological reactions relevant to bone. Materials and methodsUtilizing sulfuric acid (H2SO4) and hydrochloric acid (HCl), five distinct acid solutions were prepared, and the acid etching process was executed at five different time points at room temperature. The surface characterization of nanoscale modified titanium disks encompassed surface characteristics analysis, wettability and roughness tests. The biocompatibility evaluation involves tests that assess cell attachment, proliferation, alkaline phosphatase activity (ALP), and mineralization. ResultsThe surface modified by HCl exhibited the most significant alterations, characterized by an elevated roughness value and reduced hydrophilicity properties. The surface treated with a mixture of HCl and H2SO4 for 24 h (TH5) displayed a hydrophilic surface and high surface energy. Acid etched surfaces showed the greater cell attachment with long pseudopodia. The cell proliferation rate and ALP reaction rate of TH5 is the highest at day 7. Cells mineralization of Ti surface treated with 37% HCl for 24 h (TC5) shows the lowest and TH5 shows the greatest on day 21. ConclusionThe proposed acid etching at room temperature utilizing a combination of H2SO4 and HCl demonstrated improved physical properties while fostering favorable biological responses.

Heavy Metals Levels and Contamination Status in Soils of Koudalwa, Tchad

This study is aimed at determining the heavy metal levels in agricultural soils and around oil drilling pits in Koudalwa, Tchad and evaluating pollution levels. Soil sampling was done on three sites AA (AA1 & AA2), BB (BB1 & BB2), CC (CC1 & CC2) with two samples collected per site, giving a total of six samples. The subsamples with code one represent the 0-30 cm depth and code two represent the 30-60 cm depth. A control sample was taken far from sites having any oil activities. 2 mm sieved soil samples were digested in a mixture of HCl and HNO<sub>3</sub> in the ratio 1:3 and the concentrations of Cr, Cd, Pb, Hg, Cu, Mn, Fe and Ni in the digested solutions determined by atomic absorption spectroscopy. The contamination level of the heavy metals was assessed using the Geo-Accumulation Index (Igeo), Contamination factor, Pollution load index (PLI), Enrichment Factor (EF), and Potential Ecological Risk Assessment (PER) models. Results obtained shows that the abundance of heavy metals in the soils of Koudalwa is in the order; Cu ˃ Hg ˃ Cr ˃ Mn ˃ Fe ˃ Cd ˃ Ni ˃ Pb. The site AA shows the highest levels of all the determined heavy metals except Ni with highest amount of Cr (197.98 mg/kg), Cd (6.49 mg/kg), Hg (531.46 mg/kg), Ni (0.088 mg/kg) in the 30-60 cm soil depth, and Pb (0.021 mg/kg), Cu (815.24 mg/kg), Mn (166.55 mg/kg) and Fe (60.04 mg/kg) in the top soil, 0-30 cm depth. PLI analysis confirms that sites AA1 and AA2 present a decline of site quality as compared to other sites which are of perfect site quality. ER values for Cd, Cr, Cu, Hg showed severe enrichment due to contributions of anthropogenic sources with higher values in subsurface samples, thus indicating their high mobility in these soils. Results of this study shows that critical attention must be given to site AA as well as other activities in other sites that can contaminate the soils with special focus on remediation measures and sensitization of the population on the dangers of different activities on the soils.

Evaluation of Heavy Metals in Roadside Soil of Tumfure Main Market, Gombe State

Heavy metal pollution has been a problem of concern in soil ecology in recent decades. This study evaluated the physico-chemical characteristics and heavy metal contents in roadside soil samples of Tumfure main market, Gombe, Nigeria. The soil samples were collected from six different sampling points with a control sample each by handpicking, this was followed by oven-drying, ground to fine grain, and then sieved using a 2 mm mesh sieve. The pH, electrical conductivity and bulk density were carried out on the soil samples, sieve and sedimentation method were used to determine the soil texture. The soil samples were weighed and digested using mixture of HCl and HNO3. The contents (mg/kg) of four metals (cadmium, copper, lead and zinc) were estimated using Atomic Absorption Spectrophotometer (AAS). Among the metals analyzed, the contents of Cd, Cu and Pb were not detected while the content of Zn (23.454 - 36.026) was found to be within the desirable permissible limits by the World Health Organization (WHO) and European Regulatory Standards (EURS) whose prevalence is to be considered non-toxic in unpolluted soils.

Study on the Influence of Etchant Composition and Etching Process on the Precision of Stainless‐Steel Microchannel and Etching Mechanism

The chemical etching method has the advantages of high precision and low cost for the preparation of steel surface microchannel, but the composition of the etching solution and the etching process have a great influence on the precision of the microstructure. In this article, the influence of etching solution composition and the etching time on the etching precision of stainless steel using a mixture of HCl and H2O2 as an etching solution is studied. The reactions and passivation processes that occur during the etching process are analyzed. The etching mechanism is revealed. The sample prepared with HCl:H2O2 = 1:2 can obtain better etching precision and high‐dimensional stability. The amount of lateral erosion and the depth of etching increases with the increase of etching time, resulting in a decrease in the etching factor and precision. Pitting and intergranular corrosion mainly occur during the etching process, and the loss of metal chloride formed in the process forms holes, which become rapid diffusion channels for corrosive Cl and O elements, and promotes the etching process. The etching reaction forms a passivation film on the surface of the substrate, which reduces the rate of the etching reaction.

Evaluation of the effectiveness of mixing hydrochloric acid and organic acid as stimulation fluids in a tight gas carbonate reservoir

AbstractMatrix acidizing is a widely used technique in carbonate formations to improve production and injection rates by restoring or improving permeability. This study evaluates the stimulation efficacy of organic and inorganic acid combinations in the Sarajeh carbonate formation, with a focus on improving permeability within this potential tight gas formation. Through solubility and continuous flow tests, a mixture of HCl 7.5% + HAc 2.5% was found to significantly outperform the traditional HCl 15% solution. The HCl 7.5% + HAc 2.5% mixture had a solubility rate of 59.27% and improved permeability by 4.4 times compared to HCl 15%, indicating a higher dissolving capacity. The results of continuous flow tests showed that the mixed acid had the best pore volume to breakthrough (PVBt) value of 2.574 at a controlled injection rate of 2 cc/min. This study demonstrates the superior performance of a lower concentration HCl‐HAc acid formulation in matrix acidizing carbonate formations and confirms its potential as a more effective alternative to high concentration HCl treatments for the Sarajeh reservoir.

Geochemical base for As, Co, Cu, Ni, P, Pb, S, V and Zn in road dust collected in areas of oil industry activity in the Metropolitan Region of Salvador, Bahia, Brazil

Road dust collection was carried out in Salvador and some municipalities in the Metropolitan Region of Salvador (MRS), such as Simões Filho, Candeias, Madre de Deus and São Francisco do Conde, situated within an area of oil activity. In the chemical-physical characterisation of the road dust collected, the average fractions of coarse sand (17.44 %), medium (27.15 %), fine (32.63 %) and very fine (15.54 %) were found in the 17 samples collected. The samples underwent an acid extraction procedure in a closed digester block, with the mixture HCl + HNO3 + H2O2. The extract was analysed and concentrations of Al, As, Co, Cu, Fe, Ni, Pb, P, Sb, V and Zn were determined. Linear regression analysis was applied to the concentrations of As, Co, Cu, Ni, Pb, P, V and Zn, generating the equations of the straight lines, which served as a geochemical baseline for the region of road dust samples. For the enrichment factor (EF), most chemical elements showed values lower than < 1 at the collection points, except for Cu, Mn, and P (10 < EF < 25) and for Co, Cu, P and Ni (5 < EF < 10), in the regions of Candeias and Simões Filho. On the other hand, the geoaccumulation index (Igeo) of most points were evaluated as uncontaminated (class 0) and moderate or uncontaminated (class 1) for Igeo, except for P (class 4) and Mn (class 5). Principal component analysis (PCA) showed accumulated total variance corresponding to 76.45 %. For the hierarchical cluster analysis (HCA), the results agree with those found in the PCA. Points P3 (Candeias) and P16 (Simões Filho) were the points that showed less dissimilarity with the other points analysed, indicating possible enrichment of the chemical elements found at these points, confirmed by the EF values.

Functionality of chemical additives and experimental conditions during formation of acid-induced emulsion and sludge

Petroleum has still maintained its position among energy sources, and there is a considerable demand for its higher production. A viable process that could improve oil production is acid stimulation. In this process though, acid-induced emulsion and sludge formation may profoundly compromise its performance. This study concentrates on experimental evaluation of these drawbacks considering the influence of several chemical additives that are usually used in acid stimulation including corrosion inhibitor, corrosion inhibitor intensifier, suspending, and iron control agents. In addition, the effect of operating conditions such as the volumetric ratio of acid and crude oil, mixing shear, ferric ions concentration, and various acid systems were studied during emulsion phase separation and sludge formation. Acid systems including HCl 15 and 28 wt% solutions, spent HCl, hybrid (a mixture of HCl and acetic acid), and emulsified acids (HCl in diesel) were also investigated. The results confirmed that although the additives are necessary for their main functionalities, nonetheless, they postponed the emulsion phase separation for at least 30 min. They also showed only meagre impact on the amount of formed sludge (<1 %), and a meaningful relationship could not be established between their presence and sludge formation. The acid phase volumetric ratio had an inverse impact on emulsion stability in such a way that 10 times more emulsion break happened by increasing the volumetric ratio from 0.25 to 0.75. Unlike previous studies, ferric ions formed less stable emulsions due to the presence of corrosion inhibitor and iron control agents. However, they were not able to control sludge formation. In addition, hybrid and emulsified acids showed high acid-crude oil emulsion stability for all samples along with higher amounts of sludge. Finally, spent acid showed less affinity to form sludge and emulsion.

Determination of the active ingredient amounts of expired albendazole drugs

In this study, it was aimed to determine the active ingredient amounts of 24 expired and 3 unexpired antiparasitic drugs containing the active ingredient albendazole using UV-Vis and RP-HPLC techniques. The drugs were prepared using methanol (MeOH) and 1 N HCl (70:30, v/v) mixture. The quantitative analyses of albendazole were carried out at 338 nm in the range of 1.562-75 µg mL-1 (R2=0.9997) in UV-Vis. In RP-HPLC, separations were achieved using Nucleosil 100-5, C18 column (250 x 4.6 mm, 5µm) in isocratic elution. 0.02 M phosphate buffer (pH 3.0) and MeOH mobile phase (30:70, v/v) were used at a flow rate of 1.0 mL min-1. Detections were conducted in the same concentration range (R2=0.9998) using a PDA detector (210 nm). The results obtained using both techniques were evaluated by taking into account the studies in the literature. In this study, it was determined that the loss of active ingredient in veterinary drugs containing different albendazole active ingredient examined decreased over time and that some drugs containing albendazole active ingredient on the market may have less active ingredient amount than the acceptable limit values.

Synthesis and biological evaluation of selenopyrimidine derivatives bearing thiazolyl moiety

The aim of this study is to explain how new thiazole and selenophene moieties were obtained from 2-amino-4-(4-methylthiazol-2-yl)selenophene-3-carbonitrile (3) and to assess the antioxidant and cytotoxic properties of these new compounds. Compound 3 is prepared and subjected to react with each of CS2, malononitrile in EtOH/TEA, ECA, a mixture of HCl and AcOH, formamide, formic acid, malononitrile in the presence of EtONa to give their corresponding selenopyrimidine and selenopyridine derivatives 4–10. Moreover, compound 3 reacted with thiourea, hydrazine hydrate, CS2 in NaOH/DMF, and phenyl isothiocyanate to afford selenolo[2,3-d]pyrimidines 11–17 and related compounds. The recently synthesized compounds were tested for their DPPH radical scavenging and cytotoxic properties against the HePG-2 and MCF-7 cell lines. Compounds 5 and 11 demonstrated potential radical scavenging activity, but compounds 5 and 6 exhibited the strongest cytotoxic action against the examined cell lines. According to molecular docking data, the compounds under research are intriguing candidates for the development of new anticancer therapeutic targets.

Determination of technology-critical elements in seafood reference materials by inductively coupled plasma-tandem mass spectrometry

The certified reference materials (CRMs) BCR-668 (mussel tissue), NCS ZC73034 (prawn), NIST SRM 1566a (oyster tissue) and NIST SRM 2976 (mussel tissue) were analyzed for their mass fractions of 23 elements using inductively coupled plasma tandem-mass spectrometry (ICP-MS/MS). This study focused on the quantification of selected technology-critical elements (TCEs), specifically rare earth elements (REE) and the less studied TCEs Ga, Ge, Nb, In and Ta. Microwave assisted closed vessel digestion using an acid mixture of HNO3, HCl and H2O2 was applied to varying sample masses and two different microwave systems. Recoveries of 76% (Gd, NCS ZC73034) to 129% (Lu, BCR-668) were obtained for the REE and 83% (Ge, NCS ZC73034) to 127% (Nb, NCS ZC73034) for the less studied TCEs across all analyzed CRMs (compared to certified values) using the best-performing parameters. Mass fractions for all analyzed, non-certified elements are suggested and given with a combined uncertainty U (k = 2), including mass fractions for Ga (11 µg kg-1 ± 9 µg kg-1 to 67 µg kg-1 ± 8 µg kg-1) and In (0.4 µg kg-1 ± 0.3 µg kg-1 to 0.8 µg kg-1 ± 0.7 µg kg-1). This study provides mass fractions of possible new emerging contaminants and addresses the relevant challenges in quantification of less studied TCEs, thus allowing the application of existing CRMs for method validation in studies dealing with the determination of TCEs in seafood or other biota.Graphical abstract

Heat utilized pressure swing distillation (PSD) process for the separation of the maximum boiling azeotrope HCl and Water in the Cu-Cl Cycle

The four-step copper-chlorine cycle is utilized for hydrogen production from water. Intermediate copper and chlorine compounds facilitate the process, while all other reactants are regenerated and recycled, forming a closed-loop system. Hydrolysis of CuCl2, leading to the formation of Cu2OCl2 and dilute HCl, is a crucial step that uses a large excess of steam to ensure completion of reaction leading to the formation of dilute hydrochloric acid which needs to be recycled for the electrolysis reaction, requiring removal of the azeotrope between HCl and water. This study explores the utilization of pressure swing distillation (PSD) for concentrating HCl above azeotropic composition. Separation of the aqueous mixture of HCl and water using PSD is optimized using a sequential iterative optimization technique, focusing on process intensification. Integration of a simple heat-utilized FE-Process results in a reduction of TAC and energy cost (4.27% TAC and 7.20% energy cost) compared to the process without heat integration. A higher feed composition of HCl (8 mol %) leads to savings of ∼ 38.75% in TAC and a reduction of 53.06% in CO2 emissions compared to a lower feed composition (2.53 mol % HCl). The heat-utilized FE-Process with a higher feed composition is more economically viable for the separation of HCl and water.

Ecological and Human Health Risk Assessment of Heavy Metals in Sediment of Selected Creeks in Rivers State, Nigeria

There has been much concern about the rate at which industrial and household wastes are released into Creeks in Rivers State. The study examined the status of heavy metal pollutants (Cd, Cu, Zn, Cr, Pb, and Ni) in sediment and to determine the extent of damage caused by these human factors using the most recent pollution index and Sediment quality guidelines (SQGs). The research was carried out in four important creeks along the Delta River network in Rivers State, Nigeria (Okrika, Borokiri, Eagle Island, and Kaa). Triplicate sediment samples were collected at a depth of 0-20 cm and extracted with 20cm3 of aqua ragia (a 3:1 mixture of HCl and HNO3) and 10cm3 of 30% H2O2. The metal concentrations were measured using an Atomic Absorption Spectrophotometer (AAS). The concentrations of the heavy metals ranged from 11.147–18.919mg/kg, 11.918–14.379mg/kg, 8.321–11.691 mg/kg, 6.405–11.72mg/kg, and 5.718–12.125mg/kg, and 2.429-7.725mg/kg respectively and followed the sequence Zn &gt; Pb &gt; Cr &gt; Ni &gt;Cu &gt; Cd. Geo-accumulation Index (Igeo) calculated was less than 0 i.e. uncontaminated for all metals except Pb in Borokiri Creek and Cd in all sampled creeks, showing moderate contamination. Eco-toxicological risk assessment (RI) indicated that the creeks were uncontaminated. Despite the low level of contamination, it is recommended that relevant authorities to regulate the indiscriminate dumping of domestic waste and untreated industrial effluents into the river to prevent the deterioration of the creeks

ANALYSIS OF ACID MIXTURE COMPARISON ON THE PROCESS OF DESTRUCTION OF LEAD METAL (Pb) ON SAMPLE OF CARPET SHELL’S MEAT (Ruditapes variegatus)

ABSTRACT&#x0D; &#x0D; Analysis of the acid mixture ratio in the lead (Pb) metal deconstruction process in carpet shell’s meat samples (Ruditapes variegatus). In the deconstruction agent HNO3 : HCl (1:3), the average lead metal concentration contained in sweet clam meat is 4.6305 ± 1.066 mg/kg and for the HNO3 : H2SO4 (3:1), the average lead metal concentration contained in the same sweet clam meat was 5.6516 ± 2.556 mg/kg. Statistical test results showed no significant difference in the dissolving power of the acid mixture HNO3 : HCl (1:3) and HNO3 acid mixture: H2SO4 (3:1) as seen from the p&gt;0.005 value, so both the HNO3 acid mixture: HCl (1:3) and HNO3 acid mixture: H2SO4 (3:1) can be used to deconstruct Pb metal in sweet clam meat (Ruditapes variegatus) because there is no significant difference in the two acid mixtures.

Prediction of cosolvent effect on solvation free energies and analysis of intermolecular forces of tizanidine hydrochloride in ethyl acetate + methanol / ethanol mixtures

The solubility of small molecule drug in solvents can be dramatically affected by addition of a suitable cosolvent, which makes the screening of the best-suited cosolvent an important task for the purification and preparation. The present work aims to improve the fundamental understanding of tizanidine hydrochloride (TIZ HC) solvation by cosolvent. Solubility experimental data from TIZ HCl in mixtures of ethyl acetate + alcohols were obtained at different temperatures with the method of isothermal equilibrium. In the system of ethyl acetate + methanol, the solubility data increased firstly and then decreased with an increase in ethyl acetate content, however, the strictly monotonic decreasing of solubility in ethyl acetate + ethanol mixtures was observed. The solubility correlation fitting was performed with the Jouyban-Acree model and CNIBS/R-K model. The solvent effect analysis indicates that the hydrogen bond acidity, the polarity / polarizability and the cohesive forces of the solvent have a greater influence on the solubility, which was further validated by the local quantitative molecular surface analysis results of electrostatic potential (ESP). The dissolution process of TIZ HCl in systems with different solvent compositions was analyzed in the form of preferential solvation parameters, it was found that methanol is the preferred solvent in the solvation shell of TIZ HCl in methanol-rich and ethyl acetate-rich mixtures but the ethanol is preferred in intermediate compositions and ethyl acetate-rich mixtures. Moreover, the types of intermolecular solute–solvent interactions were discussed on the basis of the structural characteristics of TIZ HCl. The solvation free energy is a key parameter describing solvent effects, which is extremely important for understanding solution chemistry. For this part, with the aid of density functional theory (DFT) and molecular dynamics (MD) simulations, it was found that the cosolvent effect is consistent with the prediction trend of solvation free energy of TIZ HCl in each systems. The effect of the cavity formed by the solvent molecules and dipole moment of solute was calculated accordingly by the solvation model based on density (SMD) for explaining the former behavior.

Extractive extraction for platinum recovery using synergistic organic formulation of Aliquat 336/TBP mixtures

The source of platinum in the earth’s crust has become diminishing nowadays, thus recycling platinum from a secondary source is highly demanded. Hydrometallurgical processes have been used as an alternative method instead of pyrometallurgical. In this process, extractive solvent extraction is the core of operations. This study aims to find the synergistic formulation for platinum extraction as well as to study the extraction and stripping mechanism of the separation process. The extraction was performed by using a synergist organic formulation of basic and solvating where Aliquat 336 and tributyl phosphate (TBP) were used as a base and synergist extractant, respectively. Palm cooking oil was used as a green diluent. At 5x10-5 M TBP + 5x10-4 M Aliquat 336, 85% of platinum was extracted and the synergistic coefficient (SC) in this work was 1.29. Aliquat 336 acts as a synergist while TBP acts as a base. Based on the mechanism, it was concluded that one mole of Aliquat 336 and one mole of TBP can extract one mole of platinum ion. Then, the stripping process of the loaded extractant/platinum was done using the mixture of HCl and thiourea. At the optimum concentration of the stripping agent (0.5 M HCl + 0.5 M thiourea), 93% platinum was stripped which was considered a high stripping efficiency. Therefore, the synergistic formulation of the extractive extraction process offers great potential for platinum recovery from the aqueous solution.

Molecular imprinted polymer-based potentiometric approach for the assay of the co-formulated tetracycline HCl, metronidazole and bismuth subcitrate in capsules and spiked human plasma

BackgroundAn anti-H-pylori co-formulated mixture of tetracycline HCl (TET), metronidazole (MET), and bismuth subcitrate (BSC) is recently available. Only two chromatographic and spectrophotometric methods are reported for determining those drugs simultaneously where the effect of impurities that could be present as well as the biological fluids matrix influence do not be taken into consideration. There is a need to develop an easy-to-use potentiometric technique for analysis of TET, MET, and BSC in their co-formulated capsules, in presence of some official impurities and in spiked human plasma. ResultsThree carbon paste electrodes (CPEs) were fabricated for this purpose. Being a solid contact ion-selective electrode, CPE suffers from the creation of a water layer affecting its stability and reproducibility. Besides, it has a common problem in differentiation between two drugs carrying the same charge (positively charged TET and MET). Water layer formation was prevented through inserting polyaniline nanoparticles (≈10.0 nm diameter) between solid contact and ion-sensing membrane in the three proposed sensors. TET and MET interference was overcome by synthesizing a corresponding molecular imprinted polymer (MIP) for each drug. The synthesized MIPs were inserted in equivalent sensing membranes and characterized using several techniques. The suggested MIPs have a noticeable enhanced sensitivity in potentiometric determination. The obtained LODs were 5.88 × 10−8, 5.19 × 10−7, and 1.73 × 10−6 M for TET, MET and BSC proposed CPEs, respectively, with corresponding slopes of 57.37, 56.20, and −57.40 mV decade−1. SignificanceThe proposed potentiometric method makes the detection of the three cited drugs simple, fast, and feasible. This approach is the first for determining three drugs potentiometrically in one combined formulation. The obtained results were compared favorably with previously reported potentiometric methods.