Hydroquinone In Solution Research Articles

Кинетика фотоокисления двухатомных фенолов в присутствии пероксида водорода и персульфата калия

Today, wastewater treatment from organic ecotoxicants is one of the most important tasks. Scientists all over the world are working to find an effective and harmless technology for the removal and/or complete destruction of organic pollutants. One of the solutions is technologies using ultraviolet lamps with various catalysts. UV technologies have recently been widely used in various industries, especially in water treatment and water treatment processes. The attractiveness of photolysis is due to the fact that these methods are considered environmentally friendly and are listed in the directories of the best available technologies. In the course of the work, a number of experimental studies were carried out to identify the regularities of the kinetics of the photodestruction processes of diatomic phenols in model aqueous solutions under the action of active particles. All processes were carried out on a laboratory flow-type installation. A 254 nm bactericidal, special ozone-free lamp from OSMAR, Finland, with a power of 9 watts was chosen as an ultraviolet emitter. The contact time of the model solution with the reactor varied from 20 to 120 s. The quantitative determination of diatomic phenols was carried out by the spectrophotometric method. Hydrogen peroxide (3% solution) and potassium persulfate were selected as catalytic additives. In the course of the work, the possibilities of impacts to achieve high efficiency of water purification from diatomic phenols were identified. The paper presents the results of photooxidation of aqueous solutions of pyrocatechin, resorcinol and hydroquinone in the presence of microadditives of hydrogen peroxide and potassium persulfate. The volume of microadditives was varied according to the stoichiometric ratio from 1 to 5 fractions. It has been shown that photodestruction of diatomic phenols is possible with an efficiency of up to 99%. At molar ratios, phenol:oxidizer - 1:5 there is an increase in the rate of the photooxidation reaction by 3-5 times. It has been established that the benzene ring breaks during the destruction process, and the main decomposition products of diatomic phenols are monobasic carboxylic acids and formaldehyde.

Effect of Potassium Peroxodisulphate and Microwave Power on Hydrogel Character Based on Banana Peel Waste Using Microwave Grafting Method

<p><em>Musa paradisiaca var. raja</em> peel waste contains cellulose which has the potential to be a raw material for synthesizing hydrogels. This research utilizes acrylamide monomer grafted onto banana peel cellulose backbone using the microwave grafting method to produce hydrogel. The banana peel waste was dried to a constant weight and then crushed into powder. Banana peel powder was through a delignification process with the addition of NaOH and bleached with NaClO to took only the cellulose of the banana peel. The mixture of banana peel cellulose-acrylamide-potassium peroxodisulfate powder through the grafting process was repeated with variations in KPS concentration and microwave power. The reaction was terminated with a hydroquinone solution, washed with acetone, and then precipitated. The precipitated solid was dried to a powder called cellulose-g-PAAM. A homogeneous solution of 2% carrageenan-cellulose-g-PAAM underwent a physical crosslinking process using KCl and CaCl<sub>2</sub> solutions after passing through palm oil to form a bead gel. The purpose of this research was to determine the effect of potassium peroxodisulfate (KPS) initiator concentration and microwave power on the swelling capacity in water. The properties of obtained dried bead gels were characterized their functional groups using FTIR and swelling capacity test in water. From this research, it can be concluded that banana peel cellulose was successfully grafted onto acrylamide monomer as evidenced by the FTIR test results. The lower KPS concentration is the greater on the swelling capacity and the microwave power has no effect on the swelling capacity of bead gels.</p><p><strong>Keywords: </strong>Banana peel, Bead gel, Microwave, Swelling degree </p>

Characterization of a Ruthenium(II) Complex in Singlet Oxygen-Mediated Photoelectrochemical Sensing.

A water-soluble ruthenium(II) complex (L), capable of producing singlet oxygen (1O2) when irradiated with visible light, was used to modify the surface of an indium-tin oxide (ITO) electrode decorated with a nanostructured layer of TiO2 (TiO2/ITO). Singlet oxygen triggers the appearance of a cathodic photocurrent when the electrode is illuminated and biased at a proper reduction potential value. The L/TiO2/ITO electrode was first characterized with cyclic voltammetry, impedance spectroscopy, NMR, and Raman spectroscopy. The rate constant of singlet oxygen production was evaluated by spectrophotometric measurements. Taking advantage of the oxidative process initiated by 1O2, the analysis of phenolic compounds was accomplished. Particularly, the 1O2-driven oxidation of hydroquinone (HQ) produced quinone moieties, which could be reduced back at the electrode surface, biased at -0.3 V vs Ag/AgCl. Such a light-actuated redox cycle produced a photocurrent dependent on the concentration of HQ in solution, exhibiting a limit of detection (LOD) of 0.3 μmol dm-3. The L/TiO2/ITO platform was also evaluated for the analysis of p-aminophenol, a commonly used reagent in affinity sensing based on alkaline phosphatase.

Evidence of Gas-Phase Attachment of Molecular Oxygen to Deprotonated Hydroquinone During Ion-Mobility Mass Spectrometry.

Gas-phase addition of dioxygen to certain ions is a well-known phenomenon in mass spectrometry. For this reaction to occur, the presence of a distonic radical site on the precursor ion is thought to be a prerequisite. Herein, we report that oxygen adduct formation can take place also with deprotonated hydroquinone, which in fact is an even-electron species without a radical site. When the product-ion spectrum of the m/z 109 ion, generated by electrospray ionization from a solution of hydroquinone in acetonitrile, was recorded under ion-mobility conditions, a new peak was observed at m/z 141. However, an analogous peak was not visible in the spectrum acquired under nonmobility conditions (i.e., without any gas introduced to the mobility cell). Presumably, traces of oxygen present in the collision gas instigate an ion-molecule reaction to produce an adduct of m/z 141, which upon activation results in CO and H2O loss to form a product ion of m/z 95. Isotope-labeling studies confirmed that one of the hydrogen atoms from the hydroxy group and another from the aromatic ring contribute to the water loss instigated from the m/z 141 adduct. Furthermore, computational methods indicated the three-dimensional structure of the ground-state deprotonated hydroquinone to be distinctly different from those of its 1,2- and 1,3-isomers. Calculations predicted that all atoms in the two m/z 109 ions generated from catechol and resorcinol lie on one plane. In contrast, the structure of the m/z 109 ion from hydroquinone was significantly different. Computations predicted that the hydrogen atom on the intact hydroxyl group of deprotonated hydroquinone protrudes out of plane from rest of the atoms. Consequently, the exposed OH group can interact with an incoming dioxygen molecule. Computations conducted at the CAM-B3LYP/6-311++g(2d,2p) level of theory detected a minimum energy crossing point (MECP) at -4.3 kJ mol-1 below the separated O2 + deprotonated hydroquinone triplet threshold. In contrast, similar calculations conducted for catechol and resorcinol yielded MECPs of +116.9 and +69.1 kJ mol-1, respectively, above the associated triplet thresholds. These results indicated that the curve crossing required to form singlet products upon reaction with triplet O2 is favorable in the case of hydroquinone and unfavorable in the cases of catechol and resorcinol. In practical terms, the selective oxygen addition appears to be a diagnostically useful reaction to differentiate hydroquinone from its ring isomers.

Identifikasi Hidrokuinon Pada Krim Pemutih Wajah Yang Beredar Di Pasar Central Tompasobaru

The board of trustees of medicine and food throughout Indonesia was keeping a routine check on cosmetics that ran from October 2014 to September 2015, there are 30 types of cosmetics that contain the dangerous materials of 13 types of cosmetic product and 17 types of domestic production. The harmful substances identified in such cosmetics as K3 and K10 red dye (Rhodamin B), retinoic acid, mercury and hydroquinine. Hydroquinone is a supposition or a device that ACTS to treat hyperpigmentation in the outer part of the body as skin. Hyperpigmentation is the process by which skin is exposed to such areas as pimples, scars, or brown spots from frequent exposure to sunlight. Excessive use of hydroquinone can cause ookronosis, namely the skin has nodules like sand and bluish-brown in color, people with ookronosis will feel the skin like burning and itching. This type of research is descriptive, which aims to describe and describe the presence or absence of hydroquinone in facial whitening creams. The method used for laboratory testing is qualitatively using the thin layer chromatography method. Sampling using purposive sampling method, namely sampling where the sample taken is a cream that does not have a permit from the Food and Drug Supervisory Agency. From the results of research that has been carried out on three face whitening creams circulating in the Central Tompasobaru market and do not have a permit from the Food and Drug Supervisory Agency, one of which was declared positive for containing Hydroquinone, it is shown from the results of a qualitative test using the thin layer chromatography method which has the same value. with a standard solution of hydroquinone, which is Rf = 0.84 and under UV light 254 has a blackish fluorescence.

Hydroquinone Solubility in Pure and Binary Solvent Mixture at Various Temperatures with FTIR

Gravimetric method is used to measured hydroquinone solubility in water, ethanol and in water+ethanol binary mixtures at temperatures (293.15, 295.15, 298.15, 300.15, 303.15, 305.15, 308.15, 310.15 and 313.15)K. Mole fractions solubility of hydroquinone are correlated with temperature by using the Apelblat equation. The combined nearly ideal binary solvent (NIBS)-Redlich-Kister equation is used to fit experimental hydroquinone solubility data in mixed solvents at constant temperature. ΔH0soln, ΔG0soln, and ΔS0soln are thermodynamic functions of hydroquinone in different solvents, obtained from the modified van’t Hoff equation. FTIR study is done for some hydroquinone solution.

Boron nitride with high zeta potential via plasma processing in solution for preparation of polyrotaxane composite

Plasma processing in solution is effective for the preparation of composites. To optimize the plasma processing in solution, a method that can be used to sufficiently evaluate the surface modifications is necessary. In this study, to identify such a method, hexagonal boron nitride (hBN) particles modified by plasma processing in solution and exhibiting different zeta potentials were used to prepare a polyrotaxane composite. Plasma processing in a hydroquinone solution yielded hBN particles with a high zeta potential, named HQpBN, and x-ray computed tomography showed a uniform dispersion of the HQpBN/polyrotaxane composite. The tensile strength and elongation of the HQpBN/polyrotaxane composite were twice as high as those of an unmodified hBN/polyrotaxane composite, in which hBN particles aggregated. These results demonstrate that the zeta potential of the modified particles can be used as an indicator to guide optimal surface modification during plasma processing in solution for the preparation of homogeneous composites.

Comparison of effects of 5% hydroquinone cream plus non-ablative fractional 1540 erbium YAG laser and 5% hydroquinone cream alone in the treatment of melasma

Background: Melasma is an acquired Hypermelanosis often difficult to treat. In this study, we assessed efficacy and safety of 5% hydroquinone cream plus non-ablative fractional 1540 erbium YAG laser and 5% hydroquinone cream alone in the treatment of melasma Methods: We selected 40 patients of melasma aged between 18 and 60 years for the study. Group 1 were treated with a cream of 5% hydroquinone and group 2 treated with a solution of hydroquinone 5% plus three sessions of non-ablative fractional 1540 erbium YAG laser at monthly interval. Improvement was assessed by the melasma-area-and-severity-index (MASI) score. Results: The two groups did not differ significantly in (MASI( score in the first month of treatment (p = 0/135), while during the second to fifth months, there were significant differences between the two groups (p <0.05) and (MASI( score was more reduced in the second group. The two groups did not show significant differences in the incidence of complications (erythema, hyperpigmentation, hypopigmentation). (p= 0/746, 0/158, 0/574, 0/135, 0/135 respectively, the first month, second month, third month and fourth month) Conclusion: A combination of hydroquinone and laser therapy had better results in the treatment of melasma. But due to some disagreements about the use of lasers in the treatment of melasma we recommend more studies with larger sample size to be taken to definitely show better therapeutic effect of laser.

Chitosan-coated magnetic nanoparticles used as substrate immobilization carrier for α-arbutin biosynthesis process

Chitosan-coated magnetic nanoparticles (MNPs@CTS) which used as substrate immobilization carrier of glucosyl acceptor for α-arbutin production is introduced in this study. Fe3O4@CTS microspheres were prepared via an oxidation hydrothermal method, and further modified with chitosan. Substrate hydroquinone (HQ) was immobilized on the Fe3O4@CTS. When 1.0 g/L Fe3O4@CTS was shaken in HQ solution (7.0 g/L) at 28 °C with 120 rpm for 12 h, the maximum amount of HQ immobilization on the Fe3O4@CTS could reach 312 mg HQ per gram Fe3O4@CTS. The optimal reaction conditions for α-arbutin synthesis were also investigated. When 25 g/L Fe3O4@CTS@HQ (70.9 mM HQ) was shaken in fermentation broth at 30 °C with 180 rpm for 40 h, the final yield of α-arbutin reached 7.85 g/L. This work is useful for the industrial-scale production of α-arbutin.

Tracing nitrogenous byproducts during ozonation in the presence of bromide and ammonia using stable isotope labeling and high resolution mass spectrometry

Ammonia has been widely used to inhibit bromate formation during ozonation. However, our recent study found that during ozonation in the presence of bromide and ammonia, toxicity increased under certain conditions that might be attributed to the formation of nitrogenous byproducts. Herein, a typical structural moiety of natural organic matter (NOM), hydroquinone, was evaluated for its potential to form nitrogenous byproducts. During ozonation of the hydroquinone solution containing bromide and ammonia, toxicity of organic byproducts increased significantly. As organic bromine was hardly detected, organic nitrogen was responsible for the increased toxicity. An effective method combining ultra-performance liquid chromatography in tandem with high resolution mass spectrometry (UPLC-HRMS) with an isotope labeling strategy was used to trace nitrogenous byproducts. Four newly formed nitrogenous byproducts were detected, two of which were also detected in Suwannee River natural organic matter (SRNOM) solution treated under the same ozonation condition. Furthermore, the molecular structures and formation pathways of these nitrogenous byproducts were proposed. This study highlights that, despite the widespread use, adding ammonia to inhibit bromate formation during ozonation might increase the toxicity posed by nitrogenous byproducts. During ozonation in the presence of bromide and ammonia, particular attention should be paid to nitrogenous byproducts.

Aqueous dispersion of hexagonal boron nitride via plasma processing in a hydroquinone solution

Plasma processing in a solution with a hydroquinone additive was performed for the aqueous dispersion of hexagonal boron nitride (h-BN), and the effect of the hydroquinone additive was determined by analyzing the zeta potential distribution. The hydroquinone additive enhanced plasma modification in the solution to produce well-dispersed h-BN particles separated by centrifugation. The mean zeta potential improved up to −50 mV at neutrality and maintained in a pH range of 6–9. Infrared absorption spectra suggested that the dispersed h-BN particles were modified with hydroxyl functional groups by plasmas in the solution.

Label‐free Immunosensor for the Determination of Microcystin‐LR in Water

AbstractThis paper describes the development of a label‐free electrochemical immunosensor based on polyethyleneimine‐stabilized magnetite nanoparticles (MGNnP‐PEI) for the determination of microcystin‐LR (MC‐LR). MGNnP‐PEI was immobilized on the glassy carbon electrode (GCE) surface and employed as a platform for anchorage of the anti‐MC‐LR. Hydroquinone in solution was used as a redox probe. After optimization, the immunosensor exhibited a linear response to MC‐LR concentrations in the range of 0.1 to 500 ng mL−1 with a calculated detection limit of 0.053 ng mL−1. The immunosensor was satisfactorily applied in the quantification of MC‐LR in a water sample collected from a freshwater lagoon.

Processes for Electrochemical Production of Electrolyte-free Hydrogen Peroxide

Hydrogen peroxide is the focus of growing attention for distributed manufacturing, reflecting its decentralized applications and shipping hazards. Two recent reports, one in Science by Wang and colleaugues and one in this issue of Joule by Surendranath, Hatton, and colleaugues, introduce innovative electrochemical methods to produce electrolyte-free aqueous solutions of hydrogen peroxide.

Sensitive and Simultaneous Determination of Hydroquinone and Catechol in Water Using an Anodized Glassy Carbon Electrode with Polymerized 2-(Phenylazo) Chromotropic Acid

Hydroquinone (HQ) and catechol (CT) are considered as environmental pollutants with high toxicity. We have developed a simple electrochemical sensor using an anodized glassy carbon electrode modified with a stable 2-(phenylazo) chromotropic acid- (CH-) conducting polymer (PCH/AGCE). The PCH/AGCE sensor showed good electrocatalytic activity and reversibility towards the redox of HQ and CT in phosphate buffer solution (PBS, pH 7.0). The cyclic voltammetry (CV) in mixed solution of HQ and CT showed that the oxidation peaks of them became well resolved with a peak separation of 0.1 V. The detection limits of HQ and CT were 0.044 and 0.066 μM, respectively, in a wide linear response range of 1–300 μM for both. Moreover, the sensor displayed an excellent selectivity in the presence of common interferences. This study provided a simple, sensitive, and high recovery method for simultaneous and quantitative determination of HQ and CT in aqueous medium.

Modeling and Experimental Studies on Ozone Absorption into Phenolic Solution in a Rotating Packed Bed

Ozonation in rotating packed bed (RPB) is a promising method to treat organic pollutants in wastewater. Mass transfer efficiency of ozone in RPB is of importance to the application of this method. In this work, an overall volumetric mass-transfer coefficient (KGa) model of ozone absorption into organic solution accompanied by an irreversible pseudo-first-order reaction in an RPB was established. The mass transfer processes in both the packing and cavity zones in the RPB were considered for modeling KGa. The predicted and experimental KGa agreed well with the deviations within 10% and 15% for a hydroquinone solution and phenol solution, respectively, suggesting that this model has good predictability for the mass transfer process of ozone absorption into organic solutions with different reaction rates in RPB. It is also noted that the ozone absorption percentage in phenol solution was 40%–60%, but a much higher ozone absorption percentage in hydroquinone solution of 80%–95% was achieved due to a higher KGa...

New cathodic peak of quinone caused by the ultrafast diffusion of protons in unbuffered aqueous solution

The electrochemical behavior of hydroquinone in unbuffered aqueous solution was investigated using cyclic voltammetry. Subsequent cathodic scan showed a new cathodic peak at the negative potential and another similar cathodic peak for catechol. The peak current increased with the increasing pH of the bulk solution and concentration of hydroquinone. We observed that only the new cathodic peak increased, whereas the other peaks remained constant with the addition of quinone to the test solution. This new cathodic peak was caused by the ultrafast diffusion of proton from the electrode surface to the bulk solution. The results can help us understand the unique characteristics of hydroquinone in unbuffered solution.

Treating the Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate) Surface with Hydroquinone Enhances the Performance of Polymer Solar Cells.

The introduction of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as a standard hole transport layer greatly increased the efficiency of early organic solar cells. However, because PEDOT:PSS has a metallic property, it can still form a barrier by means of metal-semiconductor contact at its interface with the photoactive layer. In this study, we modified the PEDOT:PSS surface with hydroquinone (HQ) to remove that barrier. HQ treatment of the PEDOT:PSS surface lowered the hole transport barrier at the interface between the PEDOT:PSS and the active layer. In addition, because of the secondary doping effect of HQ, the sheet resistance of the PEDOT:PSS surface decreased by almost 2 orders of magnitude. As a result, the device fabricated with the HQ-modified PEDOT:PSS showed a 28% increase in efficiency compared to the device without HQ treatment. Modifying the PEDOT:PSS surface with HQ solution is an easy way to effectively boost the performance of polymer solar cells.

Development of technology for the alkylation of hydroquinone with aliphatic alcohols

The paper presents the results of research of technology of alkylation of hydroquinone, propyl, isopropyl, isobutyl and tert-butyl alcohols in the presence of concentrated phosphoric acid. The temperature of the alkylation reaction was maintained between 70–72 °С. On the basis of literature data and preliminary investigations the reaction was performed for 4 hours. Upon completion of the reaction, we removed the unreacted hydroquinone, aliphatic alcohol and phosphoric acid are added to a solution of distilled water (solvent corresponding connections) and sodium bicarbonate to slightly acidic (pH 5–6). For separation from the reaction medium of alkylhydroquinones in the reaction mixture was added benzene in which the original hydroquinone dissolves much less. Concentration of the benzene extract alkylhydroquinones conducted by Stripping the solvent under vacuum at temperatures above 70 °С in air atmosphere. Higher temperature vacuum distillation AIDS in the oxidation of alkylhydroquinones to alkylphenones. Precipitated after crystallization, alkylhydroquinones were dried under vacuum in a drying pistol at 56 °С. Dried products were identified by defining the melting temperature, the study of spectral characteristics and qualitative reactions with FeCl3. We also studied the solubility of alkylhydroquinones in various solvents, which showed low solubility of alkylhydroquinones in water, benzene, toluene and higher solubility in propyl and isopropyl alcohols and in acetone. Analysis of the results shows that the obtained alkylhydroquinones are not chemically pure compounds, and contain in their composition of admixture source of hydroquinone. Qualitative reactions of solutions of alkylhydroquinones with FeCl3 solution differ from the corresponding reaction of a solution of hydroquinone. The results of investigations of electronic absorption spectra of alkylhydroquinones and source of hydroquinone in isopropyl alcohol solution did not significantly differ from each other and have a maximum absorption at ? = 210 nm. From the presented investigations it follows that the maximum efficiency of the alkylation of hydroquinone was studied aliphatic alcohols in acidic medium is observed for t-butyl alcohol.

Efficient detection of hazardous catechol and hydroquinone with MOF-rGO modified carbon paste electrode

Reduced graphite oxide (rGO) was incorporated into a metal organic framework (MOF) MIL-101(Cr) for the modification of carbon paste electrode. Taking advantages of the large surface area of MOF and the electrical conductivity of rGO, the resulted electrodes exhibited high sensitivity and reliability in the simultaneous electrochemical identification and quantification of catechol (CC) and hydroquinone (HQ). Specifically, in the mixture solution of catechol and hydroquinone (constant concentration of an analyte), the linear response ranges for catechol and hydroquinone were 10–1400 μM and 4–1000 μM, and detection limits were 4 μM and 0.66 μM (S/N = 3) for individual catechol and hydroquinone, respectively. Therefore, the relatively easy fabrication of modified CPE and its fascinating reliability towards HQ and CC detection may simulate more research interest in the applications of MIL-101(Cr)-rGO composites for electrochemical sensors.

Phenolic profiles in apple leaves and the efficacy of selected phenols against fire blight (Erwinia amylovora)

The content and type of phenolic compounds in apple leaves as potential markers of resistance to fire blight were analysed. The amounts of phenolic acids and flavonoids were determined before and after E. amylovora inoculation of leaves of two cultivars: ‘Enterprise’ (highly resistant) and ‘Idared’ (highly susceptible). The basic levels of phenolics in both cultivars was similar but, following the inoculation, in the resistant one faster and more distinguishable changes were observed. The difference between the cultivars was related to the content of the compounds and the rate of release of free phenols from their glucosides. Regarding age dependency, the levels of eight out of 15 phenolics was significantly higher in young leaves of ‘Idared” than in ‘Enterprise’. In the older leaves the differences were limited to four compounds. The amount of salicylic acid in ‘Idared’ was lower than in ‘Enterprise’. In ‘Idared’ accumulation of salicylate after infection was better pronounced than in ‘Enterprise’. Higher levels of naringenin glucosides, 4-hydroxbenzoic acid and gentisic acid were found in ‘Enterprise’. The activity of 13 phenolics tested in vitro against the pathogen showed that gallic acid, phloroglucinol, hydroquinone and phloretin, suppressed its growth. The aqueous solutions of gallic acid, phloroglucinol and hydroquinone also significantly limited the development of disease on pear fruitlet slices but only hydroquinone maintained its protective activity for longer time. It also showed very high efficacy in preventing disease spread on apple shoots. The study adds novel information on the contribution of specific phenolics to apple resistance to fire blight.