scholarly journals Removal of chromium (VI) ions from aqueous solutions

2021 ◽  
Vol 5 (3(61)) ◽  
pp. 17-20
Author(s):  
Tetiana Obushenko ◽  
Nataliia Tolstopalova ◽  
Mariia Chyrieva
Keyword(s):  
Organic Solvent ◽  
Cationic Surfactant ◽  
Butyl Alcohol ◽  
Process Efficiency ◽  
Molar Ratio ◽  
Chromium Vi ◽  
Carcinogenic Effects ◽  
Real Wastewater ◽  
Flotation Method ◽  
Living Organisms

The object of the research is the flotoextraction of chromium (VI) ions from model and real waste waters. Hexavalent chromium compounds pose a serious hazard to surface and ground waters and can have mutagenic and carcinogenic effects on living organisms. The study of the process of flotoextraction as a method of purifying waste water from heavy metals using the example of chromium (VI) ions is an important task. The paper considers flotoextraction of chromium (VI) ions using a cationic surfactant – hexadecylpyridinium chloride and butyl alcohol as the organic phase. The dependences of the process efficiency on the presence of a cationic surfactant, the flotoextraction time, the type of organic extractant, the nature of the collector and the surfactant: Cr molar ratio, the initial concentration of pollutants, and the pH of the initial solution were obtained. Certain rational conditions for flotation allow removing 98–99.6 % of pollutants. The method was tested on real wastewater. The importance of this study is emphasized by the fact that flotoextraction has a number of features and advantages. In particular, the possibility of multiple concentration of pollutant ions in small volumes of an organic solvent and the possibility of its further regeneration. In this case, a much smaller amount of an organic solvent is used and the process is not limited by the distribution constant (compared to the extraction method). Flotoextraction is also characterized by the absence of foam (compared to the flotation method) and the absence of large amounts of wet sludge (compared to the reagent method). The proposed method provides a sufficient level of chromium ions removal from wastewater, and can also be used in systems for local wastewater treatment with the subsequent return of water to the technological process. This will ensure a reduction in costs for the consumption of water resources, discharge of wastewater into water bodies, and also limit the ingress of harmful substances into the environment.  

Degradation of an Azo Dye by Fenton Type Processes Assisted with UV Irradiation

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Natalija Koprivanac ◽  
Dinko Vujevic
Keyword(s):  
Uv Irradiation ◽  
Azo Dye ◽  
Dye Degradation ◽  
Degradation Products ◽  
Batch Reactor ◽  
Process Efficiency ◽  
Molar Ratio ◽  
Synthetic Dyes ◽  
Ambient Conditions ◽  
Treatment Methods

Organic synthetic dyes are widely produced and used today. Significant losses of organic and inorganic content occurs during the manufacturing and application of dyes and its discharge in the effluent presents a threat to the eco-systems due to general toxicity and resistance to destruction by biological treatment methods. Particularly azo dyes are of special environmental concern due to their degradation products such as aromatic amines, which are considered highly carcinogenic. So, dyes have to be removed from coloured wastewater before discharge. However, traditional treatment methods (adsorption, coagulation/flocculation) mainly transfer the contaminants from wastewater to secondary waste. Therefore, advanced oxidation processes seem to be sustainable and clean technology to decolorize and minimize organic dyes content from wastewater. In this paper, degradation of an azo dye C.I. Direct Orange 39 (DO39) using Fenton type processes (Fe2+/H2O2, Fe3+/H2O2and Fe0/H2O2) has been performed. The molar ratio of Fenton’s type reagents has been varied in the range of 1 : 5 up to 1 : 50 at 0.5 and 1.0 mM concentrations of iron salts and iron powder. Experiments have been conducted for two hours in a batch reactor with magnetic stirring, ambient conditions and pH 3. The process efficiency and formation of degradation by-products have been determined on the basis of results obtained by UV/VIS spectrophotometric, total organic carbon (TOC) and high performance liquid chromatography (HPLC) analyses. The optimal Fenton and Fenton ``like" processes parameters have been applied in the photo reactor, too. It has been observed that simultaneous utilization of UV irradiation with Fenton's and Fenton ``like" reagents increases the degradation of DO39 dye. Degradation of the dye in dilute aqueous solution follows pseudo-first order kinetics. The maximal decolourization of 20 mg L-1 DO39 in water of 93.2% and TOC degradation of 76.9% were obtained using Fe3+/H2O2= 1 : 5 molar ratio. The results indicate that the treatment of DO39 dye wastewater with UV/Fe3 +/H2O2 system was found to be the most efficient.

Effects of organic solvents on immobilized enzyme catalyses. Chymotrypsin immobilized on porous glass

1981 ◽  
Vol 59 (19) ◽  
pp. 2921-2925 ◽  
Author(s):  
J. Bryan Jones ◽  
Diana H. Pliura
Keyword(s):  
Organic Solvent ◽  
Organic Solvents ◽  
Porous Glass ◽  
Immobilized Enzyme ◽  
Butyl Alcohol ◽  
Solvent Concentration ◽  
Marked Contrast ◽  
Practical Applications ◽  
Tert Butyl Alcohol ◽  
Esterolytic Activity

The esterolytic activity of native chymotrypsin (CT) immobilized on ionically neutral porous glass beads has been studied in the presence of up to 20% (v/v) of the organic solvents methanol, ethanol, 2-propanol, tert-butyl alcohol, dioxane, and DMSO. In marked contrast to the variations observed with native CT, inhibition of CT immobilized on glass (CT–glass) was independent of the nature of the organic solvent. The overall activity, as indicated by kc(app)/km(app), decreased by 35–50% as the concentration of all solvents surveyed was increased up to 20%. In general, high organic solvent concentration accelerated the rate of protein release from the insoluble catalyst. For practical applications in aqueous organic solvents CT–glass conjugates are inferior to those of the enzyme attached to Sephadex.

Polar Probe Study of Water-Organic Solvent-Macromolecule Emulsifier Aggregates Structure

2013 ◽  
Vol 717 ◽  
pp. 233-239
Author(s):  
Hong Jing Zhang
Keyword(s):  
Ethylene Glycol ◽  
Organic Solvent ◽  
Crude Oil ◽  
Structural Properties ◽  
Theoretical Basis ◽  
Butyl Alcohol ◽  
Methyl Red ◽  
Polar Medium ◽  
Micellar Aggregates ◽  
Polar Probe

In this paper, using methyl red as polar probe, a containing LPS macromolecule emulsifier (HBS-1, MW is about 106Da) micellar aggregates in different polar medium (ethanol, n-butyl alcohol, ethylene glycol and DMF) structural properties, and provide a theoretical basis for the mechanism of the emulsified crude oil.

scholarly journals Chemical Reactivities of ortho-Quinones Produced in Living Organisms: Fate of Quinonoid Products Formed by Tyrosinase and Phenoloxidase Action on Phenols and Catechols

2020 ◽  
Vol 21 (17) ◽  
pp. 6080 ◽  
Author(s):  
Shosuke Ito ◽  
Manickam Sugumaran ◽  
Kazumasa Wakamatsu
Keyword(s):  
Nucleophilic Addition ◽  
Quinone Methide ◽  
Side Chain ◽  
Amino Groups ◽  
Melanin Biosynthesis ◽  
Fast Reactions ◽  
Carcinogenic Effects ◽  
Oxidation Of Phenols ◽  
Living Organisms ◽  
Cellular Components

Tyrosinase catalyzes the oxidation of phenols and catechols (o-diphenols) to o-quinones. The reactivities of o-quinones thus generated are responsible for oxidative browning of plant products, sclerotization of insect cuticle, defense reaction in arthropods, tunichrome biochemistry in tunicates, production of mussel glue, and most importantly melanin biosynthesis in all organisms. These reactions also form a set of major reactions that are of nonenzymatic origin in nature. In this review, we summarized the chemical fates of o-quinones. Many of the reactions of o-quinones proceed extremely fast with a half-life of less than a second. As a result, the corresponding quinone production can only be detected through rapid scanning spectrophotometry. Michael-1,6-addition with thiols, intramolecular cyclization reaction with side chain amino groups, and the redox regeneration to original catechol represent some of the fast reactions exhibited by o-quinones, while, nucleophilic addition of carboxyl group, alcoholic group, and water are mostly slow reactions. A variety of catecholamines also exhibit side chain desaturation through tautomeric quinone methide formation. Therefore, quinone methide tautomers also play a pivotal role in the fate of numerous o-quinones. Armed with such wide and dangerous reactivity, o-quinones are capable of modifying the structure of important cellular components especially proteins and DNA and causing severe cytotoxicity and carcinogenic effects. The reactivities of different o-quinones involved in these processes along with special emphasis on mechanism of melanogenesis are discussed.

High-Performance Liquid Chromatography Determination of Acrylamide after Its Extraction from Potato Chips

2019 ◽  
Vol 25 (4) ◽  
pp. 338-344
Author(s):  
Maryam Ghalebi ◽  
Samin Hamidi ◽  
Mahboob Nemati
Keyword(s):  
Organic Solvent ◽  
Organic Phase ◽  
High Performance ◽  
Single Step ◽  
Potato Chips ◽  
Process Efficiency ◽  
Local Market ◽  
Good Precision ◽  
Time Saving ◽  
Relative Standard

Background: Acrylamide is a known carcinogenic product that has been found among the substances such as potato chips which to be processed under the heat-treatment. In order to extract amounts of acrylamide from fried chips in market, an ultrasound-assisted liquid– liquid extraction (UA-LLE) technique is proposed. The UA-LLE coupled LLE and ultrasonication in a single step. Methods: Chips samples were dissolved in an extracting organic solvent using ultrasonication to prompt transferring of acrylamide into the organic phase. As a result, the extraction time and process efficiency were significantly enhanced through increasing the collision power and mass transfer between grounded chips and organic phase. Results: Important parameters affecting the extraction efficiency such as kind of organic solvent and its volume, re-dissolving solvent and pH were optimized. This newly proposed method has been applied to determine the trace acrylamide in potato chips samples purchased from local market. Conclusion: UA-LLE is a handy, economic and time-saving method, with high extraction yield (over 103% average recovery) and good precision (lower than 15% relative standard deviation, RSD). Most importantly, it seems this method to be an ideal pre-treatment method for the extraction of acrylamide in food matrix in food quality control laboratories.

Reentrant swelling behavior of poly(4-vinyl phenol) gel in aqueous organic solvent mixtures

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Michiko Sakurai ◽  
Mitsuru Satoh
Keyword(s):  
Organic Solvent ◽  
Mixed Solvents ◽  
Butyl Alcohol ◽  
Poly Vinyl Alcohol ◽  
Solvent Mixtures ◽  
Oh Groups ◽  
Solvent Content ◽  
Water Composition ◽  
Vinyl Phenol ◽  
Pva Gel

AbstractSwelling behaviours of poly(4-vinyl phenol) (P4VPh) hydrogel in various kinds of mixed solvents (methanol, ethanol, 2-propyl alcohol, t-butyl alcohol, acetone, acetonitrile, dioxane, THF and DMSO) have been investigated. With increasing the organic solvent content, the gel first significantly deswelled and then reswelled via lowest swelling points (10-60 vol.% depending the solvent species), and finally showed a second deswelling in the highest content region (typically ≧ 80 vol.%). The rather unique swelling-deswelling sequence was not reproduced when the solvent content was decreased; namely, the backward swelling curves obtained with increasing water composition in the mixed solvents first followed the forward one until the lowest swelling points, then, however, continued the deswelling trend without recovering the initial swelling state in water. This remarkable hysteresis as well as the reentrant swelling with the extra second deswelling has been interpreted in terms of the intermolecular interactions, i.e., hydrogen bonding between the phenol OH groups and the π- π stacking of the phenol rings, by referring to the corresponding results of poly(vinyl alcohol) (PVA) gel system.

Chromium(VI) adsorption from aqueous solution onto Moroccan Al-pillared and cationic surfactant stevensite

2007 ◽  
Vol 140 (1-2) ◽  
pp. 104-109 ◽  
Author(s):  
Abdelaziz Benhammou ◽  
Abdelrani Yaacoubi ◽  
Lahbib Nibou ◽  
Boumediane Tanouti
Keyword(s):  
Aqueous Solution ◽  
Cationic Surfactant ◽  
Chromium Vi

Synthesis and Characterization of Nanocrystalline Anatase by Microwave Hydrothermal Method

2012 ◽  
Vol 500 ◽  
pp. 104-107
Author(s):  
Zhi Qin Chen ◽  
Xiang Liang Chen ◽  
Shu Juan Zhang ◽  
Jun Xi Hu ◽  
Wen Kui Li
Keyword(s):  
Hydrothermal Method ◽  
Average Particle Size ◽  
Butyl Alcohol ◽  
Molar Ratio ◽  
Tetrabutyl Titanate ◽  
Average Particle ◽  
Synthesis Conditions ◽  
Microwave Hydrothermal ◽  
Microwave Hydrothermal Method

Uniform nanocrystalline pure anatase has been synthesized and characterized using tetrabutyl titanate aqueous solution as starting precursors by microwave hydrothermal method. The influences of synthesis conditions (reaction time and temperature) on the formation, crystal phase and crystallite size of TiO2has been investigated. A mixture solution of tetrabutyl titanate and normal butyl alcohol in 1:4 molar ratio is processed in a microwave hydrothermal autoclave at low temperature 120°C for different durations, at 200°C for 20 min to precipitate titania powders, respectively. It was revealed that uniformly dispersed and granulous single phase anatase prepared at 120°C for 180 min with the average particle size of 10 nm was formed by means of XRD and TEM.

Experimental Research on Apparent Viscosity Behavior of Cationic/Anionic Worm-Like Micelles

2014 ◽  
Vol 644-650 ◽  
pp. 4884-4887
Author(s):  
Ni Li ◽  
Rui Zhang
Keyword(s):  
Double Bond ◽  
Cationic Surfactant ◽  
Experimental Research ◽  
Anionic Surfactant ◽  
Apparent Viscosity ◽  
Self Assembly ◽  
Molar Ratio ◽  
Trimethylammonium Chloride ◽  
Viscosity Behavior

In this paper, cationic surfactant and anionic surfactant form worm-like micelles by self-assembly. The cationic surfactant is acryloxyethyl trimethylammonium chloride (DAC). The anionic surfactant is potassium erucic (KEU). Mixed the cationic surfactant and anionic surfactant, because the DAC molecule contain a double bond, then, polymerized the solution with VA - 044. By contrast many experiments, the purpose is to get the highest apparent viscosity. After comparing, when the molar ratio of n (KEU) : n (DAC) = 5:1, the largest viscosity of worm-like micelles is 1450mPa•s.

scholarly journals Biomimetic Synthesis of Hydroxyapatite in Presence of Imidazole-4,5-dicarboxylic Acid Grafted Chitosan for Removing Chromium(VI)

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Zhangxu Chen ◽  
Baorong Wu ◽  
Xiaodan Huang ◽  
Xianxue Li ◽  
Yonglong Lin
Keyword(s):  
Dicarboxylic Acid ◽  
Removal Rate ◽  
Biomimetic Synthesis ◽  
Molar Ratio ◽  
Optimum Conditions ◽  
X Ray ◽  
Natural Bone ◽  
Chromium Vi ◽  
Orthogonal Experiments ◽  
Novel Method

In order to biomimetic synthesize hydroxyapatite similar to natural bone. Hydroxyapatite (HAP) is biomimetic synthesized in simulated body fluid (SBF) by addition of imidazole-4,5-dicarboxylic acid grafted chitosan (IDACS). The effect of molar ratio of chitosan (CS) to imidazole-4,5-dicarboxylic acid (IDA) on preparation of HAP was investigated. The structure, size, and crystal phase of the obtained hydroxyapatite were observed by Fourier transform infrared spectroscopy, X-ray powder diffraction, and scanning electron microscopy. The results show that the molar ratio of CS to IDA is 1 : 3, the temperature is 37.0°C, the aging time is 48 h, the synthesized nanorod-like hydroxyapatite with diameter 20–30 nm, and length ranging from 75 to 120 nm presents excellent phase, which disperses well and is similar to the natural bone of HAP. The obtained HAP can be used to remove chromium(VI) by the orthogonal experiments, and the results indicated that the removal rate can reach 95.66% under the optimum conditions. These results suggest that the morphology of the obtained HAP is more affected by the material ratio of chitosan to imidazole-4,5-dicarboxylic acid than its structure, and the obtained HAP can effectively remove Cr(VI), which provides a novel method for biomimetic synthesis of other biomaterials and application in the water purification.

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