Low Concentrations Of Hydrochloric Acid Research Articles

Impact of Hydrochloric acid on breaking seed dormancy and germination enhancement in native Alhagi graecorum Boiss ( Al-Agool ).

Despite the great importance of legumes plants, most of them have a hard and impermeable testa, which causes physical dormancy of the seeds and prevents germination even when environmental conditions are favorable. This is considered one of the major problems in successful seed germination. Alhagi graecorum plant is a wild native legume. It has a hard and impermeable testa, which causes physical dormancy of seeds, and to overcome hard coat imposed dormancy, softening the hard seed coat by soaking Hydrochloric acid ( HCl ). The present study was conducted to evaluate various duration of soaking seeds in HCL to breaking physical dormancy for A.graecorum in 10, 20, and 30 minutes. The results showed that, final germination percentage (FGP) in treated seeds significantly increased when compared with the control were 55, 62 and 68 % respectively, while in control was only 12 %. Seed germination influenced by HCL is due to its capability to break the hard seed coat that leads to water absorption and imbibition of seeds. As for the mean daily germination ( MDG ), the results revealed that, there were significance increased in seventh day of sowing in germination between the treated seeds in duration of soaking 20 and 30 min were 23 and 24 % respectively, as they were most effective in germination, while the germination in the control stopped in the fifth day of sowing at 12 %. While the mean germination time (MGT), the results indicated that the seeds soaked in acid recorded 9.66, 9.13, and 8.62 days, respectively. The minimum MGT for treated seeds was detected in 30 min., 8.62 days. The reason for the long period of the mean germination time may be due to the use of a low concentration of hydrochloric acid, so I recommend using higher concentrations of acid to obtain a lower mean germination time.

Highly selective recovery of rare earth elements from mine wastewater by modifying kaolin with phosphoric acid

Recovery of rare earth elements (REEs) from mine wastewater is essential for maintaining rare earth reserves and sustainable application of REEs. In the present study, we prepared a phosphoric acid modified kaolin (P-K) adsorbent by a simple mechanochemical process for the selective recovery of REEs from rare earth wastewater. The impacts of phosphoric acid dosage, milling duration, initial pH, temperature, initial ion concentration, and adsorbent dosage on the selective adsorption of REEs were investigated. The findings demonstrate that the adsorption of REEs by P-K follows pseudo-second-order kinetic model and the Langmuir isotherm model, and is dominated by chemical adsorption, with a maximum adsorption capacity of 19.82 mg/g at 50 ℃. Additionally, in an original mine wastewater, the recovery rate of REEs can reach more than 90%, whereas the adsorption rates of calcium, magnesium and, ammonia nitrogen (whose concentration is 18 times that of REEs) are nearly zero, indicating that P-K has extremely high selectivity for REEs. Furthermore, the feedstock solution containing 40 mg/L of REEs may be concentrated to 3510 mg/L following enrichment treatment, and 99.9% of the REEs are eluted using a low concentration of hydrochloric acid. The findings illustrate that P-K has a wide range of potential applications in the treatment of rare earth industrial effluents.

The study on extraction behavior of [N1888][P507] and TRPO for heavy rare earths

Ionic liquids were extensively used in many extraction and separation processes for metal ions because of excellent dissolving and selecting ability. The COSMO-RS method was applied for selecting suitable ionic liquid from 80 kinds of ionic liquids. Hydrophilicity, solvent solubility, distribution ratio were considered as important factors for selecting suitable ionic liquids. [N1888][P507] was suitable ionic liquid for extracting and separating heavy rare earths. A solvent extraction system containing ionic liquid [N1888][P507] and molecular extractant TRPO to separate heavy rare earths was studied. The results showed that the mixture of the [N1888][P507] and TRPO contributed to high extractabilities and selectivities of heavy rare earths. The abilities to form third phase and product emulsification phenomenon decreased with the concentration ratio of TRPO and [N1888][P507] increasing. The extraction mechanism of HREEs was deduced as ion association. The quantitative stripping of HREEs from loaded organic phase could be achieved with deionized water and low concentration of hydrochloric acid. The article showed that the mixture of [N1888][P507] and TRPO might be an effective and environmentally friendly extractant for extraction and separation of heavy rare earths.

Mild Dissolution/Recomplexation Strategy for Speciation Analysis of Gadolinium from MR Contrast Agents in Bone Tissues by Means of HPLC-ICP-MS.

A species-dependent and total gadolinium quantification strategy for the analysis of bone and bone marrow samples was developed and applied to femurs of rats previously treated with different gadolinium-based contrast agents (GBCAs). A combined mild dissolution/recomplexation strategy allows the quantification of total Gd as well as the quantification of intact GBCA in bones within one analysis for the first time. Samples of rat bones and bone marrow were dissolved in low concentrations of hydrochloric acid and diethylenetriamine pentaacetate (DTPA). This is followed by the addition of excess In(III) to recomplex all free ligands, previously added DTPA as well as the ligands of GBCAs that were not stable during the dissolution step. Separation and quantification were carried out by means of high-performance liquid chromatography (HPLC) on a hydrophilic interaction liquid chromatography (HILIC) column with subsequent inductively coupled plasma-mass spectrometry (ICP-MS). The results show that the investigated GBCA with a macrocyclic ligand shows a higher tendency to stay intact in the bone tissues over time, while a GBCA with a linear ligand is decomplexed more rapidly four weeks after GBCA administration. Additionally, for all macrocyclic GBCAs, a similar limited gadolinium accumulation was observed in the bone and bone marrow. Whereas linear GBCAs showed a higher gadolinium accumulation, a difference was observed between bone and bone marrow, indicating a different biodistribution behavior.

Serum Lysophosphatidic Acid Measurement by Liquid Chromatography-Mass Spectrometry in COPD Patients.

Lysophospholipids are bioactive signaling molecules derived from cell membrane glycerophospholipids or sphingolipids and are highly regulated under normal physiological conditions. Lysophosphatidic acids (LPAs) are a class of lysophospholipids that act on G-protein-coupled receptors to exert a variety of cellular functions. Dysregulation of phospholipase activity and consequently LPA synthesis in serum have been linked to inflammation, such as seen in chronic obstructive pulmonary disease (COPD). The accurate measurement of phospholipids is critical for evaluating their dysregulation in disease. In this study, we optimized experimental parameters for the sensitive measurement of LPAs. We validated the method based on matrix, linearity, accuracy, precision, and stability. An investigation into sample extraction processes emphasized that the common practice of including low concentration of hydrochloric acid in the extraction buffer causes an overestimation of lipid recovery. The liquid chromatography gradient was optimized to separate various lysophospholipid classes. After optimization, detection limits of LPA were sufficiently sensitive for subsequent analysis, ranging from 2 to 8 nM. The validated workflow was applied to a cohort of healthy donor and COPD patient sera. Eight LPA species were identified, and five unique species of LPA were quantified. Most LPA species increased significantly in COPD patients compared to healthy donors. The correlation between LPAs and other demographic parameters was further investigated in a sample set of over 200 baseline patient sera from a COPD clinical trial. For the first time, LPAs other than the two most abundant and readily detectable moieties are quantified in COPD patients using validated methods, opening the door to downstream biomarker evaluation in respiratory disease.

Respiratory effects of occupational exposure to low concentration of hydrochloric acid among exposed workers: a case study in steel industry.

Occupational exposure to hydrochloric acid in pickling of steel for remove rust or iron oxide scale from iron processing occurs at low concentration. This study aimed to investigate the respiratory symptoms and pulmonary dysfunction caused by exposure to low concentration of hydrochloric acid in acid washing unit in one of the steel industries. A case control study was carried out in the acid washing unit of the cold rolling of the steel industry in 2017. The exposed group included 45 male workers, and another 41 unexposed employees from official employees were enrolled as control group. A questionnaire was used to collect personal and occupational data and pulmonary function tests, including forced vital capacity (FVC), forced expiratory volume in the first second and peak expiratory flow rate followed guidelines given by the American Thoracic Society and measured with a portable calibrated vitalograph spirometer. For determination of acid concentration, 21 breathing zone air samples were collected in accordance with Method 7903 NIOSH. The findings showed that nose sensitivity, throat irritation and shortness of breath were the highest prevalence symptoms among exposed persons (30.4% to 32.6%). Also, the results showed that FVC and forced expiratory volume in the first second had highest and direct or positive correlation with height (0.965 and 0.927, respectively). Age and weight put in the next priorities (P < 0.01). On the other hand, based on the results of multivariate linear regression, exposing to the acid and job history are two main predictor factors for FVC. So that, the exposing to acid, by itself can reduce FVC as 4.386 units. This value is equal to 1.117 for the job history. Exposure to low concentrations of hydrochloric acid alone could increase the risk of respiratory tract damage and pulmonary function disorders. But the extent to which it can cause respiratory complications for occupational exposure is still unknown and requires further study. This study was approved by Ethical Committee of Qom University of Medical Sciences (approval No. IR.MUQ.REC.1397.118) on November 6, 2018.

Adsorption of AuCl 4 − from Acidic Chloride Solution by Chemically Modified Lignin Based on Rice Straw

The chemically modified lignin was synthesized based on rice straw and the adsorption properties of AuCl 4 − were investigated in this paper. The adsorbent was characterized by Fourier transform infrared spectrometer, scanning electronic microscope and thermogravimetric analysis and differential scanning calorimetry. The chemically modified rice straw lignin was of excellent thermal stability and had plenty of primary amines and hydroxyls. Many influence factors such as initial concentration of AuCl 4 − , adsorption time and concentration of hydrochloric acid on AuCl 4 − were optimized. The maximum adsorption capacity was 783.94 mg·g−1. The equilibrium adsorption time was 600 min. The equilibrium isotherm fitted well with the Langmuir model and the pseudo-second-order kinetic model was suitable for describing the adsorption of AuCl 4 − . Low hydrochloric acid concentration could promote the selectivity of adsorption on AuCl 4 − . Combination of ion exchange and reduction was the mechanism. AuCl 4 − was adsorbed by ion exchange first and then reduced from hydrochloric acid medium in the form of Au(0) by phenolic hydroxyl.

Cell cycle profiling by image and flow cytometry: The optimised protocol for the detection of replicational activity using 5-Bromo-2'-deoxyuridine, low concentration of hydrochloric acid and exonuclease III.

The approach for the detection of replicational activity in cells using 5-bromo-2′-deoxyuridine, a low concentration of hydrochloric acid and exonuclease III is presented in the study. The described method was optimised with the aim to provide a fast and robust tool for the detection of DNA synthesis with minimal impact on the cellular structures using image and flow cytometry. The approach is based on the introduction of breaks into the DNA by the low concentration of hydrochloric acid followed by the subsequent enzymatic extension of these breaks using exonuclease III. Our data showed that the method has only a minimal effect on the tested protein localisations and is applicable both for formaldehyde- and ethanol-fixed cells. The approach partially also preserves the fluorescence of the fluorescent proteins in the HeLa cells expressing Fluorescent Ubiquitin Cell Cycle Indicator. In the case of the short labelling pulses that disabled the use of 5-ethynyl-2′-deoxyuridine because of the low specific signal, the described method provided a bright signal enabling reliable recognition of replicating cells. The optimized protocol was also successfully tested for the detection of trifluridine, the nucleoside used as an antiviral drug and in combination with tipiracil also for the treatment of some types of cancer.

Green process for production of 5-hydroxymethylfurfural from carbohydrates with high purity in deep eutectic solvents

5-Hydroxymethylfurfural (5-HMF) is one of the most important platform chemicals in biorefinery. In this work, an effective and green route for 5-HMF production in deep eutectic solvents (DESs) was demonstrated using extremely low concentration of hydrochloric acid as the catalyst. Moreover, the DES/acetonitrile (MeCN) biphasic reaction system adopted in this research showed excellent recyclability, which could be directly reused for multiple times without downgrading of the 5-HMF yield.

Adsorption properties of ion recognition rice straw lignin on PdCl42−: Equilibrium, kinetics and mechanism

A low cost biosorbent was synthesized based on rice straw, which showed the ability of selective adsorption on PdCl42−. Adsorption behaviors, including the effects of the initial concentration of PdCl42−, the adsorption time and the concentration of hydrochloric acid on the effect of adsorption, were explored systematically. The results showed that the saturation adsorption capacity of the sorbent on PdCl42− was 122.49mgg−1 and the equilibrium adsorption time was 60min. In addition, the adsorption obeyed the Langmuir isotherm model and pseudo-second-order kinetics model. Low hydrochloric acid concentration could promote the selectivity of adsorption and the adsorption rate went up to 92.71% when the concentration of hydrochloric acid was 0.5molL−1. Furthermore, the adsorption mechanism was investigated through the analyses of FTIR and XPS and it indicated that Pd(II) coordinated with the N of primary amine and the O of alcoholic hydroxyl except ion exchange with Cl−.

Synthesis and application of acid-gas sensing dyes having alkyl groups symmetrically substituted on monoazo chromophore

The three chromic dyes having alkyl groups symmetrically or asymmetrically substituted on azobenzene chromophore were synthesized and investigated in their color change by exposure to acid gas like hydrochloric acid in order to produce acid-gas sensing fabrics. By the specially designed dynamic color measurement system, the color change of the dyed fabrics by exposure to hydrochloric acid gas was measured in real time. The Dye(8,2,2) of the three dyes was determined as the best one considering synthesis and purification process, heat resistance, sensitivity to acid gas, and fastness on fabrics altogether. Even at very low concentration of hydrochloric acid, the color of dyed fabrics changed substantially from bright yellow to strong red. Since the color change of the dyes can be returned to its original color by ventilation, they are reusable repeatedly without significant decrease its sensing property. The fastnesses to washing, rubbing, and light were considerably good enough for practical applications.

Spectroscopic and atomic force studies of the functionalisation of carbon surfaces: new insights into the role of the surface topography and specific chemical states.

The utility of carbon materials in applications as diverse as drug delivery and photocatalysis is often undermined by the complexity of their surface chemistry; different sources of carbon give rise to a varied mixture of functional groups and hence different properties. Considerable efforts have been made to identify specific groups at these surfaces and elucidate the complex interactions that take place but even on materials such as graphene and carbon nanotubes there remains uncertainty about the nature of the components present and their role in the nucleation of other functional materials at the surface. The present study uses highly ordered pyrolytic graphite (HOPG) as a model on which the fundamental properties of specific functional groups and their interactions with deposited nanoparticles can be characterised. We have shown that treatment of HOPG surfaces with low concentrations of hydrochloric acid results in significant topographic changes to the surface and a low concentration of oxygen containing species. From selective derivatization and a comparison of their XP spectra, the latter can be unambiguously identified as surface hydroxyls. DFT calculations have shown that these groups are stable in close proximity to each other. Heating to 573 K leads to conversion of the hydroxyls to mixture of two states, one of which is identified as a ketone whilst the other is proposed to be an ether. Gold deposition on the surface from aqueous solutions of chloroauric acid is shown to be strongly influenced by the nature of the oxygen species present.

A literature review of titanium solvent extraction in chloride media

A number of organic extractants for Ti(IV) solvent extraction from chloride solutions were reviewed, including acidic organophosphorus, neutral organophosphorus and amine extractants. The extraction of Ti(IV) by acidic organophosphorus extractants is via a cation exchange mechanism in low hydrochloric acid concentration solutions, whilst in high hydrochloric acid concentration solutions, it proceeds via a solvating mechanism. The Ti(IV) extraction kinetics with D2EHPA, EHPEHPA and Cyanex 272 is very slow: more than 1 h is required to reach equilibrium in some cases. The Ti(IV) extraction kinetics with Cyanex 301 and Cyanex 302 is fast: only 2–5 min are required to reach equilibrium. The Ti(IV) extraction kinetics with neutral organophosphorus extractants, such as TBP, TOPO and TRPO is also fast: the extraction equilibrium reaches within 5 min. The extraction mechanism with neutral organophosphorus extractants is solvating. Stripping Ti(IV) from loaded acidic organophosphorus extractants including D2EHPA, EHPEHPA, Cyanex 272, Cyanex301 and Cyanex 302 is difficult, requiring H 2SO 4 solution in the presence of H 2O 2. In contrast, the stripping of Ti(IV) from neutral organophosphorus extractants is much easier with low acidic solutions. It was found that the practical application of acidic organophosphorus extractants is difficult for Ti(IV) extraction from chloride solutions due to their slow extraction kinetics and difficulty in stripping, and neutral organophosphorus extractants could be used to separate both Fe(III) and Ti(IV) from other impurities or separate Fe(III) from Ti(IV) and all other impurities.

Extraction of metals from aqueous systems employing capillary-channeled polymer (C-CP) fibers modified with poly(acrylic acid) (PAA)

Polyethylene terephthalate (PET, polyester) capillary-channeled polymer (C-CP) fibers were employed as the base structure for surface modification to provide a sorbent for solid phase extraction (SPE) of aqueous cations. Surface functionalization with polyacrylic acid (PAA) was achieved using a “grafting to” approach, yielding a stable sorbent that has the potential of being employed over a large range of pH values and a variety of sample matrices. PAA was chosen for surface modification because the repeating acrylic acid monomeric unit, which contains a carboxylic acid, has the ability to bind metal ions. In a micropipette-tip SPE format, these PAA-functionalized C-CP fibers showed the ability to efficiently bind several metals (Cu2+, Cu+, Ni2+, Fe3+, UO22+), while elution could be achieved with extremely low concentrations of hydrochloric acid (1 ml of 0.005%), resulting in overall recoveries of greater than 88%. A single tip was carried throughout the entire study as a control, and showed overall recoveries averaging 96% over the course of 19 extraction experiments and a 12-month period, demonstrating the chemical stability of the sorbent material, and suggesting the potential of the C-CP fiber SPE tips to be used multiple times.

Optical absorbance enhancement by electrochemical surface roughening of CuInS2 thin films

This work presents a simple electrochemical etching method to increase the surface roughness of copper indium disulphide (CIS) thin films using low concentration of hydrochloric acid. Film morphologies were investigated using scanning electron microscopy and atomic force microscopy. The structure of films was investigated using x-ray diffraction. A comparative study of optical properties of as-deposited and roughened CIS thin films by transmittance and reflectance experiments show a strong enhancement of absorbance for wavelengths between 600 and 900 nm.

Flow-Injection Study and Analytical Applications of the Reactions of Palladium(II) and Platinum(IV) with Tin(II) Chloride in Hydrochloric Acid Solutions

The interaction of palladium(II) and platinum(II) with tin(II) chloride in hydrochloric acid solutions was studied by flow-injection (FI) spectrophotometry. It was found using kinetic measurements in the stopped flow mode that the composition of detected products and the rate of their formation depend on the concentrations of tin(II) and chloride ions in the reaction zone and on the acidity of the solution. Optimal FI conditions were found, and the selectivity of interaction of palladium(II) with tin(II) chloride was estimated for the detection of the signal at 407 nm (yellow form) and 646 nm (green form). It was demonstrated that the reaction of the formation of yellow platinum(IV) complexes is slower than that for palladium(II), especially at rather low concentrations of hydrochloric acid in the reaction flow. Based on the detection of green complexes of palladium(II) with tin(II) chloride, a flow injection method was proposed for the selective spectrophotometric determination of palladium(II) in the presence of other platinum-group metals. The height of the recorded peak is directly proportional to the concentration of palladium(II) in the injected solution in the range of 0.028–0.300 mM. The method was used for the analysis of pharmaceuticals and industrial catalysts.

Influences of Preparation Conditions of Sols on Hardening Behaviors of Silica Gel Films for Micro-Patterning.

Changes in refractive index, thickness and structure of the poly (ethylene glycol), (PEG), -containing silica gel films, prepared under various concentrations of hydrochloric acid during the exposure to an ambient atmosphere at room temperature, have been investigated to determine the influence of preparation conditions on the hardening behavior of the films in a patterning process. The PEG-containing silica gel films, derived from silica sols which were prepared under lower hydrochloric acid concentration, showed a steep increase in refractive index and large shrinkage upon increasing the exposure time. The increase in refractive index and shrinkage of the films were found to reflect the decrease of Si-OH groups and the development of Si-O-Si network in the films, accoding to infrared absorption spectra. The process time to emboss micro-patterns was shortened by using the gel films derived from silica sols which were prepared under a low hydrochloric acid concentration. This result suggests that the silica gel film with a low degree of polymerization hardens rapidly.

Electropolymerization of Pyrrole and Electrochemical Study of Polypyrrole. 2. Influence of Acidity on the Formation of Polypyrrole and the Multipathway Mechanism

Potentiodynamic generation of polypyrrole films at an extremely low reaction rate causes the resulting material to show an additional oxidation wave that is more negative and sharper than the one normally observed. The additional peaklike oxidation wave belongs to an unknown structural entity PPy(II). The treatment of acetonitrile with basic alumina prevents its formation, whereas the addition of a low concentration of hydrochloric acid (10-5 to 5 × 10-5 M) to the acetonitrile electrolytic solution promotes its formation. However, higher concentrations of HCl (>10-4 M) results in the disappearance of the characteristic peaks of both PPy(II) and the conventional PPy(I). Instead, following the acid-catalyzed trimerization of pyrrole, an ill-defined, structurally changeable, and partially conjugated PPy(III) from electrochemical side reactions may be deposited on the electrode. In a solution of high acidity, the application of a low potential to the electrolysis passivates the electrode, owing to the formati...

Combination of micropreparative capillary electrophoresis and matrix-assisted laser desorption/ionization mass spectrometry for peptide analysis.

Signal suppression is a problem in matrix-assisted laser desorption/ionization mass spectrometry of peptides prepared by capillary electrophoresis. Many common electrolytes that are efficient for separation, such as sodium phosphate, also are strongly suppressive during laser desorption/ionization. We have tested individual electrolytes for highest performance in each step of separation and collection, respectively. Suppression is not observed if citrate, trifluoroacetic acid, or hydrochloric acid is used for collection, while phosphate still can be employed in the capillary providing excellent resolution. Low concentrations of hydrochloric acid added to the sample/matrix mixture generate mass spectra with better ion intensities than if trifluoroacetic acid or citrate is used.

Off‐line and on‐line differential pulse anodic stripping voltammetric techniques for the determination of antimony(III) and antimony(V) in zinc plant electrolyte

AbstractAntimony, in both its trivalent and pentavalent states may be detrimental to the electrochemical deposition of zinc. Ideally, therefore antimony should be monitored in both oxidation states throughout an electrolytic zinc plant. At hydrochloric acid concentrations ( &gt; 4 M) both antimony(III) and (V) present in zinc plant electrolyte can be reduced at a hanging mercury drop electrode (HMDE) to form an antimony amalgam, Sb(Hg). Consequently a very sensitive analytical signal is obtained for the determination of total antimony by differential pulse anodic stripping voltammetry (DPASV) using a 1:1 mixture of plant electrolyte and concentrated hydrochloric acid. In contrast, at low acid concentrations (0.1 M) predominantly only antimony(III) can be reduced and therefore determined in zinc plant electrolyte by DPASV at a HMDE by use of a 1:1 mixture of plant electrolyte and 0.2 M hydrochloric acid. The antimony(V) concentration is calculated by the method of subtraction of antimony(III) from total antimony. Consequently, simple addition of high and low concentrations of hydrochloric acid to zinc plant electrolyte can be used to provide a suitable electrolyte for both off‐line and on‐line methods for determining the concentration of total antimony, antimony(III) and antimony(V). The method described in this article has been applied to a wide range of zinc electrolyte samples and an on‐stream analyzer technique has been successfully used for several years at the Pasminco Metals‐BHAS electrolytic zinc plant in Port Pirrie, Australia.