Influence Of Reagents Research Articles

Synthesis of magnesium ferrite by combustion of glycine-nitrate gel: the influence of reagents on the gel-precursor and the microstructure of nanopowders

Synthesis of magnesium ferrite by combustion of glycine-nitrate gel: the influence of reagents on the gel-precursor and the microstructure of nanopowders

The Influence of Reagents on the Shape, Stability, and Toxicity of AgNPs and Their Use to Produce Polymer-AgNPs Composites

The aim of this work was to propose a simple method for synthesizing differently shaped AgNPs and to find a suitable stabilizing/capping agent to ensure the non-toxicity of AgNPs. Using a chemical method, by simply changing the volume of reducing agents, we successfully prepared colloids of differently shaped AgNPs (spherical (~10 nm), triangular (~40 nm), rodlike (~30 nm), and a mixture of these shapes). The nanoparticle sizes and shapes affect the solution color. UV-VIS spectroscopy was used to evaluate the colloidal solutions, and transmission electron microscopy was used to analyze the shape and size of the nanoparticles. To create non-toxic and stable AgNPs, it is necessary to modify the surface properties of the nanoparticles; one possibility is to create a biocompatible layer on the nanoparticle surface. We successfully applied a combination of trisodium citrate and polyvinylpyrrolidone, thereby preventing the release of silver ions, which are responsible for the toxic effects of AgNPs. The synthesized nanoparticles show very low, mostly negligible antibiofilm activity against the green algae Chlorella kessleri. AgNPs were used to prepare polymer-AgNP composite thin layers and fibers. It was proved that AgNPs can influence polymer matrix properties.

Influence of Reagents on Qualitative Indicators of Artificial Anti-Deflationary Phytocenosis on Waste from a Rare Earth Tailing Facility.

This paper presents an assessment of the effect of various reagents on the qualitative indicators of anti-deflationary single-species sowing phytocenosis on enrichment waste from rare earth ores. It has been established that tailings of loparite ores are not suitable for biological reclamation due to low values of hygroscopic moisture (0.54-2.85%) and clay particles (17.6 ± 0.6%) and high content of bioavailable forms of aluminum (504 ± 14 mg/kg). Seeds of red fescue (Festuca rubra L.) were grown on the tailings of loparite ore enrichment with the addition of opoka (O), brucite (B), and vermiculite (V). The quality of the seed cenosis was assessed by the dry biomass of the above-ground parts of the plants and the plant height. A positive effect (one-way ANOVA followed by Tukey's HSD test (p < 0.05 and p < 0.01)) of the considered combinations of reagents on the growth of above-ground biomass from 31.5% (V) to 70.3 (V + O), 82.4% (V + B), and 81.8% (V + O+B) and on plant height from 53.8% (V) up to 78.6 (V + O), 83.8% (V + B), and 75.4% (V + O+B) was revealed. The use of a combination of V + O and V + B reagents made it possible to significantly reduce the content of Al (by 19.0% and 52.8%), Sr (by 16.5% and 12.9%), La (by 65.2% and 40.6%), and Ce (by 66.8% and 41.9%) in the aerial part of the sowing phytocenosis compared to control. The results obtained here can become the basis for development of a combined sorption technology for the reclamation of technogenically disturbed lands.

Ultrasound-assisted synthesis of gold nanoparticles supported on β-cyclodextrin for catalytic reduction of nitrophenols

Nitrophenols with high toxicity are well known as one of the main pollutants in water environment while aminophenols, products of the reduction, are important intermediates in the fabrication of several drugs. Thus, the reduction of nitrophenols is considerably attractive in wastewater treatment and pharmaceutical fields. In this work, gold nanoparticles (AuNPs) catalyst was straightforwardly fabricated using β-cyclodextrin as a reducing and stabilizing agent under ultrasound irradiation. The synthetic conditions were explored via the changes in concentration of β-cyclodextrin, environmental pH, temperature and time. The synthesized AuNPs under the optimal condition showed a size distribution in range of 3–21 nm with a mean size of 12 nm. The dynamic lighting scatter and zeta potential data showed the stable colloidal solutions and X-ray diffraction and selected area electron diffraction patterns confirmed crystalline structure of AuNPs. The influence of reagents and the nanoparticles on kinetic data of the reduction was investigated. The kinetic data showed that the performance of 2-nitrophenol reduction is better than that of 4-nitrophenol while rate constants of the reduction is linear to both initial concentrations of nitrophenol substrates and catalyst amount.

Influence of Reagents on the Synthesis Process and Shape of Silver Nanoparticles.

The aim of this study was to prepare the silver nanoparticles (AgNPs) via chemical reduction and analyze the impact of used reduction agents: sodium borohydride (NaBH4), trisodium citrate (TSC), polyvinylpyrrolidone (PVP), and hydrogen peroxide (H2O2) on the reduction rate of Ag+ ions to Ag0, and on nanoparticles shape. It was proven that combinations of reduction agents dramatically influence the synthesis rate of AgNPs and the color of solutions, which depends on the shape and size of nanoparticles. NaBH4, TSC, and PVP showed good reduction power. In particular, TSC proved to be a key factor influencing the shape of AgNPs. The shape of nanoparticles influences the color of colloidal solutions. Yellow solutions, where UV-vis absorbance maxima (ABSmax) are in the wavelength interval 380–420 nm, contain spherical particles with a mean size of 25 nm, whereas the blue shift of ABSmax to wavelengths higher than 750 nm indicate the presence of triangular nanoparticles (size interval 18–150 nm). A mixture of spherical, triangular, irregular, and hexagonal nanoparticles give different color, e.g., green. The formation and stability of AgNPs was tracked by UV-vis spectroscopy, size and shape by TEM techniques, and particle size distribution was studied by particle size analyzer.

Effects of Conventional Flotation Frothers on the Population of Mesophilic Microorganisms in Different Cultures

Bioleaching is an environment-friendly and low-investment process for the extraction of metals from flotation concentrate. Surfactants such as collectors and frothers are widely used in the flotation process. These chemical reagents may have inhibitory effects on the activity of microorganisms through a bioleaching process; however, there is no report indicating influences of reagents on the activity of microorganisms in the mixed culture which is mostly used in the industry. In this investigation, influences of typical flotation frothers (methyl isobutyl carbinol and pine oil) in different concentrations (0.01, 0.10, and 1.00 g/L) were examined on activates of bacteria in the mesophilic mixed culture (Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans, and Acidithiobacillus thiooxidans). For comparison purposes, experiments were repeated by pure cultures of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans in the same conditions. Results indicated that increasing the dosage of frothers has a negative correlation with bacteria activities while the mixed culture showed a lower sensitivity to the toxicity of these frothers in comparison with examined pure cultures. Outcomes showed the toxicity of Pine oil is lower than methyl isobutyl carbinol (MIBC). These results can be used for designing flotation separation procedures and to produce cleaner products for bio extraction of metals.

Improving a procedure for determining the assay of gold in a precious alloy of different composition using a touchstone

We report testing the and jewelry alloys based on that contains nickel, zinc, palladium, using a touchstone by applying various chemical reagents and XFA (X-ray fluorescence analysis).We have improved the procedure for assessing the conformity of assay of the precious alloys based on considering the content of component composition by using the results from rubbing the alloys on a touchstone.It was established that the magnitude of assay for precious alloys in the system AuAgZnCu, determined under the action of the reagent chloric gold on the touchstone, depends on the manifestation of contrast in the course of quality reaction against a standard sample (touch-needle).Under the influence of the reagent, the alloys demonstrate chloride compounds with silver and copper, being reduced to a metal powder of black and brown color. In this case, copper dissolves while together with silver, forms an intensive residue on a strip that depends on the ligature composition of the alloy. It was established that the lower the assay of a tested sample, the greater the amount of chlorine gold that decomposes, the larger the sediment of silver chloride and the pure reduced from the reagent, and hence the darker the sediment.It has been proven that testing the precious alloys of red color from the system AuAgZnCu 585 with a content of zinc (over 2 %), nickel, indium by using a reagent based on potassium dichromate and copper chloride is not effective.The results of our analysis indicate the increased assay compared with a standard touch-needle.To eliminate this phenomenon, it is recommended that one should first determine the composition of an alloy by the XFA method and construct an algorithm for testing in accordance with the content of the alloy by other reagents.It was determined that the assay defined on a touchstone for alloys from the system AuAgZnCu 585 (a content of zinc is over 2 %) is more contrast under the influence of acidic reagents and depends on the component composition of the alloy.It has been proven that the alloy of white gold, composed of palladium and silver (AuAgPd585), is not affected by the acid reagent for assay 585.Testing the alloy of white gold (AuAgPd585) using an acid reagent for assay 750 yields the dark sediment of a bluish tint.We have established a more contrast effect on the alloys of white gold and yellow gold of assay 750 from the acid reagent for alloys of assay 750.

Removal of Pb and Zn from contaminated soil by different washing methods: the influence of reagents and ultrasound.

Pb and Zn contamination in agricultural soils has become an important issue for human health and the environment. Washing is an effective method for remediating polluted soil. Here, we compare several washing materials and methods in the treatment of Pb- and Zn-polluted farmland soil. We examined four washing reagents, hydrochloric acid, citric acid, Na2EDTA, and tartaric acid, all of which independently removed Zn at rates >65 %. Combining washing reagents markedly enhanced heavy metal removal, by using Na2EDTA and either tartaric acid or lactate in sequence: Pb and Zn removal rates improved to 84.1 and 82.1 % for Na2EDTA-tartaric acid; and to 88.3 and 89.9 % for Na2EDTA-lactate, respectively. Additionally, combining ultrasound with conventional washing methods markedly improved washing efficiency, by shortening washing duration by 96 %. We achieved similar removal rates using ultrasound for 10 min, compared with traditional mechanical vibration alone for 4 h. We concluded that treating Pb- and Zn-contaminated soil with appropriate washing reagents under optimal conditions can greatly enhance the remediation of polluted farmland soils.

The influence of reagents on the preparation of Cu nanowires by tetradecylamine-assisted hydrothermal method

Copper (Cu) nanowires are inexpensive conducting nanomaterials intensively explored for transparent conducting electrodes and other applications. Here, Cu nanowires with approximately 40-nm diameter and a few hundreds of micrometers in length were selectively and facilely synthesized by a tetradecylamine (TDA)-assisted hydrothermal method. The Cu nanowires were highly flexible and were not oxidized by oxygen in air because of TDA’s effective coating on the Cu nanowires, which was confirmed by SEM observation and FT-IR spectrum. Moreover, the Cu nanowires tended to self-assemble into close-packed bundles due to hydrophobic–hydrophobic interactions between alkyl chains of TDA. The roles of the reagents in the preparation process were investigated systematically. First, a proper concentration of TDA was essential to high-quality Cu nanowires and TDA had two effects: (1) TDA molecules could coordinate with copper cations to form Cu(II)-complex, which was then reduced to Cu by glucose; (2) In the growth mechanism of Cu nanowires, the newly formed side surfaces, {100} facets, was stabilized through chemical interactions with the nitrogen atom of TDA (capping agent). With regards to Cu source, when using cupric chloride, cupric nitride, cupric acetate, and cupric bromide, Cu nanomaterials with a variety of shapes such as nanowires, nanoparticles, hollow spheres, and nanoflakes could be obtained. Among these Cu sources, cupric chloride was a proper selection for the preparation of Cu nanowires. About reductant agents, glucose could be replaced by other reductant agents such as VC. The UV–Vis absorption spectrum showed that the Cu nanowires had an absorption peak at 580 nm and a slightly higher transmittance in the visible region. These Cu nanowires were expected to find widespread use in the applications such as fabrication of transparent electrodes for flexible electronics and display devices. This TDA-assisted hydrothermal method could be expanded to preparation of different types of Cu nanostructures.

The influence of reagent used for the precipitation of Cs 2HPW 12O 40 salt on its textural and catalytic properties

The series of Cs 2HPW 12O 40 samples was prepared using various reagents, namely Cs 2CO 3 and CsCl, as the precipitating agent. Moreover, the modification of preparation procedure consisting of HCl addition to the colloidal solution of Cs 2HPW 12O 40 salt, precipitated previously with Cs 2CO 3 and H 3PW 12O 40, was also studied. The aim of present research was to recognize the role of precipitating agent in the physicochemical and catalytic properties of Cs 2HPW 12O 40 samples. The samples were characterized by number of techniques, BET, FT-IR, 31P NMR, XRD, XPS, TPD-MS, laser diffraction, NH 3 sorption. It was observed that the lattice parameters and the environment of phosphorous were the same in all studied samples. The Cs 2HPW 12O 40 salt prepared by Cs 2CO 3 exhibited very low specific surface area of about 1 m 2/g. In contrast, the usage of CsCl yielded the sample of remarkably higher surface area (∼78 m 2/g) and dramatically higher catalytic activity for dehydration of ethanol. Thus, an effect of precipitating agent can be ascribed to its influence on the size of colloidal particles formed upon preparation procedure. It has been postulated that the adsorption of HCl/chloride ions on the surface of primary particles of Cs 2HPW 12O 40 salt facilitated the formation of mesoporous structure, which determined its sorption and catalytic properties.

Integration of Preparation and Stabilization for Hemihydrate Calcium Sulfate Whiskers

The integration process of hemihydrate calcium sulfate whiskers with optimum additives was carried out, and the influence of reagents on the crystal shape and stability of hemihydrate calcium sulfate whiskers was investigated too. The products were characterized by FT-IR, SEM and XRD.The results show that the integration of preparation and stabilization of hemihydrate calcium sulfate whiskers can be achieved with addition of 0.025% sodium stearate and 0.15% sodium oleate by adding agents in different steps.

Some regularities of chlorosilanes etherification

The influence of reagents, solvent polarity, and temperature on the etherification of chlorosilanes ClCH2SiCl3, VinSiCl3, PrSiCl3, and Ph3SiCl with ethanol was studied. Influence of reaction temperature on the ratio of the synthesized alkoxysilane and related side-product siloxane is revealed. Use of excess alcohol is shown to increase the content of siloxane. Introduction of FeCl3 does not affect the synthesis. Solvents are shown to influence the reaction rate: the rate constant increases with increasing ɛ parameter of the solvent. The rate constant of etherification of chlorosilanes with ethanol falls in the series: ClCH2SiCl3 > VinSiCl3 > PrSiCl3. An explanation of the regularities is suggested.

Influence of the reagent pretreatment of wastewaters from chemical plants on the efficiency of their biological treatment

Structure formation in the flocculant-wastewater component system was studied by viscometry and IR spectroscopy. Statistical treatment of the experimental data revealed regular trends in the influence of the polymeric reagent on the efficiency of the biological oxidation of phenol, nonionic synthetic surfactants, and oxygen-consuming compounds as a whole.

Reversible Transformations of Gold Nanoparticle Morphology

Herein is reported a metamorphosis taking place in a gold nanosized system. The observed phenomenon of shape and size transformations was found to be completely reversible. Unlike most procedures in the literature where shape and size control occur in the synthetic step by adding growth- and shape-controlling agents such as surfactants or polymers, in this system postsynthetic changes in shape and size can be carried out simply by changing the ratio of reactive, competing reagents, more specifically, alkylthiols versus tetralkylammonium salts. Interestingly, the transfer of gold metal occurs (large prismatic particles to small particles and vice versa) under the influence of reagents that do not cause such interactions with bulk gold. All intermediate steps of the morphology change were observed using HRTEM and electron diffraction. The processes of breaking down and "welding back" solid metal nanoparticles occur under mild conditions and are remarkable examples of the unique chemical properties of nanomaterials. The described process is expected to be relevant to other nanoscale systems where similar structural circumstances could occur.

Spectrophotometric Determination of Nitrite and Nitrate in Cured Meat by Sequential Injection Analysis

ABSTRACT: A robust, automated, labor‐saving, accurate, and economical sequential injection system was developed for simultaneous determination of nitrite and nitrate in cured meat samples, based on the Shinn reaction. Nitrite is coupled and diazotized with sulfanilamide and N‐(1‐naphtyl)‐ethylenediamine dihydrochloride, to form a colored compound that absorbs at 538 nm. Nitrate is previously in‐line reduced to nitrite in a copperized cadmium column and measured as nitrite. The solutions' aspiration sequence, the influence of reagent and buffer concentrations, the manifold parameters, and the characteristics of the reducing column were studied. Nitrite and nitrate can be determined within the 0.030 to 1.22 of N‐NO2− and 0.034 to 3.95 mg/L of N‐NO3− ranges, respectively, at a sampling rate of 9/h. Detection limits of 9 μg/L of N for nitrite and 9 μg/L of N for nitrate were obtained, and the conversion rate of nitrate to nitrite was 100.6%± 1.8%. The results were in good agreement with those obtained by the reference methods, with relative standard deviations (r.s.d.) better than 3.70% for nitrites and 2.42% for nitrates.

Differential pulse cathodic stripping adsorption voltammetric determination of trace amounts of lead using factorial design for optimization

A sensitive cathodic stripping voltammetric method is developed for determination of lead(II), with adsorptive collection of complexes with Pyrogallol red (PGR) on to a hanging mercury drop electrode. After accumulation of the complex at −0.80 V vs. Ag/AgCl reference electrode, the potential is scanned in a negative direction from −0.20 to −0.50 V with differential pulse method. Then the reduction peak current for the lead(II)–PGR complex is measured at −0.39 V. The influence of reagent and instrumental variables was completely studied by factorial design analysis. The optimum analytical conditions for the determination of lead(II) were established. Under optimum conditions, lead(II) determined in the range of 0.1–30.0 ng ml −1 with a limit of detection of 0.06 ng ml −1. The method is successfully applied to determination of lead(II) in water sample.

Flow injection catalytic determination of ruthenium with spectrophotometric detection

A new flow injection catalytic method was described for the determination of ruthenium(III) based on its catalytic effect on the oxidation of brilliant cresyl blue (BCB) by periodate in acidic media. The reaction was followed spectrophotometrically by measuring the absorbance of the dye at 635 nm. Under optimum conditions, ruthenium can be determined in the range of 1.0–100.0 ng ml−1 with a relative standard deviation of 1.1% and with a limit of detection of 0.70 ng ml−1. The influence of reagent and manifold variables were studied and optimized. The method was tested for the determination of ruthenium(III) in some synthetic mixtures.

Determination of Ultratrace Amounts of Ruthenium by Differential Pulse Voltammetry Using Factorial Design for Optimization

A simple and sensitive electrochemical technique for the convenient determination of trace amounts of ruthenium was developed, based on the catalytic current of a Ru(III)–bromate system on the surface of a hanging mercury electrode at about −0.2 V versus Ag/AgCl reference electrode. The influence of reagent and instrumental variables was completely studied by factorial design analysis. Optimum analytical conditions for the determination of ruthenium were established. Ruthenium(III) can be determined in the range 0.005–0.350 μg/ml with a limit of detection of 0.003 μg/ml. The influence of potential interfering substances on the determination of ruthenium was studied. The method was evaluated by analyzing synthetic samples.

APTT in Heparinized Plasma: Influence of Reagent, Acute-Phase Reaction, and Interval Between Sampling and Testing

Plasma samples from 10 healthy persons and 10 patients with acute-phase reaction were heparinized in vitro to obtain 0.00-0.70 U/ml. The activated partial thromboplastin time (aPTT) was then determined, using an optical method (Automated Coagulation Laboratory) and four reagents (actin, Cephotest, Platelin, and Throm bosil). The heparin sensitivity showed variation between individuals and was lower in acute-phase plasma than in normal plasma. There was also a marked difference in heparin sensitivity among the different reagents; actin was the least sensitive reagent, while Platelin was the most sensitive reagent in normal plasma and Thrombosil the most heparin-sensitive reagent in acute-phase plasma. Delay in testing prolonged the aPTT values in both acute- phase and normal heparinized plasma. With actin and Ce photest, a delay of 90 min at 22°C resulted in 30-50% prolongation of the aPTT. A delay of 150 min caused a prolongation of 75-110% with actin. Cephotest, Platelin, and Thrombosil were less prolonged. Ex vivo samples from heparinized plasma showed similar degrees of pro longation. Storage at 4°C resulted in less prolongation. Assuming a therapeutic range of 0.35-0.70 U/ml of hep arin, the therapeutic aPTT ratio ranges in heparinized, acute-phase plasma were 1.5-3.0 for actin and 2.5-4.5 for Cephotest, Platelin, and Thrombosil. These results un derscore certain limitations in monitoring heparin therapy with the aPTT system. Unless the assay is performed within 30 min after sampling, unduly prolonged aPTT val ues will be recorded. This may lead to underdosing of the patient.

State-of-the-Art Review : Activated Partial Thromboplastin Time in Heparinized Plasma: Influence of Reagent, Acute-Phase Reaction, and Interval Between Sampling and Testing

Plasma samples from 10 healthy persons and 10 patients with acute-phase reaction were heparinized in vitro to obtain up to 0.70 U/ml. Activated partial throm boplastin time (APTT) was then determined using an op tical method (Automated Coagulation Laboratory or ACL Machine) and four different reagents (Actin, Ceph otest, Platelin, and Thrombosil). Heparin sensitivity var ied between individuals, and it was lower in acute-phase plasma than in healthy plasma. There was also a marked difference in heparin sensitivity among the different re agents; Actin was the least sensitive reagent, while Plate lin was the most sensitive reagent in healthy plasma and Thrombosil the most sensitive reagent in acute-phase plasma. Delay in testing prolonged the APTT values both in acute-phase and healthy heparinized plasma. With Ac tin and Cephotest, a delay of 90 min at 22°C resulted in 30-50% prolongation of APTT. A delay of 150 min caused a prolongation of 75-110% with Actin. Cephotest, Plate lin, and Thrombosil were less prolonged. Ex vivo samples from heparinized plasma showed similar degrees of pro longation. Storage at 4°C resulted in less prolongation. Assuming a therapeutic range of 0.35-0.70 U/ml of hep arin, the therapeutic APTT ratios in heparinized acute- phase plasma were 1.5-3.0 for Actin and 2.5-4.5 for Cephotest, Platelin, and Thrombosil. These results un derscore certain limitations in monitoring heparin therapy with the APTT system. Unless the assay is performed within 30 min after sampling, unduly prolonged APTT values will be recorded, which may lead to giving the patient an inappropriately small dose of heparin.