Visible absorption spectroscopy study of the adsorption of Congo Red by montmorillonite

AbstractThe adsorption of the anionic dye Congo Red (CR) by Na-, Cs-, Mg-, Cu-, Al- and Fe-montmorillonite was investigated by electronic spectroscopy. Spectra of the aqueous suspensions of different clay concentrations and different loadings were recorded. The spectra were curve fitted and were compared to spectra of aqueous solutions of CR at different pH values. Four bands representing anionic varieties and two representing protonated varieties of CR were identified in spectra of CR-treated Na-, Cs-, Mg-, Cu- and Al-montmorillonite. Spectra of CR-treated Femontmorillonite were slightly different, showing three bands representing anionic varieties and four representing protonated CR. The ratio between areas of bands, which represent the protonated varieties, and those representing the anionic varieties were determined showing correlation with the acidity of the metallic cation. The clay in the aqueous suspensions became coloured after the adsorption of CR. The following stainings were obtained, Na- and Mg-clay, red, Cs-clay, violet-red, Cu-clay, reddish-violet, Al-clay, dark violet and Fe-clay, dark blue. It appears that CR can serve as an indicator of the surface acidity of montmorillonite. The effects of aging on the sorption of the dye and on the surface-acidity of the CR-clay complex were investigated.

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Direct Fluorescent Detection of Organothiophosphorus Pesticides and Some of Their Sulfur-containing Breakdown Products After Thin Layer Chromatography

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/50.5.1088 ◽

1967 ◽

Vol 50 (5) ◽

pp. 1088-1098

Author(s):

Mohamed Tawfik H Ragab

Keyword(s):

Thin Layer ◽

Ethyl Acetate ◽

Thin Layer Chromatography ◽

Ultraviolet Light ◽

Congo Red ◽

Fluorescent Detection ◽

Bromine Vapor ◽

Layer Chromatography ◽

Sulfur Containing ◽

Dark Blue

Abstract A rapid, simple, convenient, and widely applicable method for the direct fluorescent detection of organothiophosphorus pesticides and some postulated breakdown products of these compounds is presented. The coinpounds were spotted on thin layer chromatographic sheets, developed in ethyl acetate :nhexane, and made visible by exposure to bromine vapor followed by spraying with ferric chloride and 2-(o-hydroxy phenyl) benzoxazole. Of the 47 compounds tested, 32 compounds produced fluorescent blue spots vinder longwave ultraviolet light; these consisted of 25 organothiophosphorus pesticides, 5 sulfur-containing breakdown products, and phosphoric and hypophosphorous acids. A superimposed Congo red spray destroyed the fluorescence and resulted in dark blue spots against a red backgrovind. The sensitivity of this method is in the range of 0.2 to 5.0 μg, depending on the specific compound.

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Fractal humic acids in aqueous suspensions at various concentrations, ionic strengths, and pH values

Colloids and Surfaces A Physicochemical and Engineering Aspects ◽

10.1016/s0927-7757(96)03949-0 ◽

1997 ◽

Vol 127 (1-3) ◽

pp. 57-68 ◽

Cited By ~ 35

Author(s):

N. Senesi ◽

F.R. Rizzi ◽

P. Dellino ◽

P. Acquafredda

Keyword(s):

Humic Acids ◽

Ph Values ◽

Aqueous Suspensions

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Chemisorption of methylene blue by kaolinite

Clay Minerals ◽

10.1180/claymin.1967.007.1.02 ◽

1967 ◽

Vol 7 (1) ◽

pp. 19-31 ◽

Cited By ~ 8

Author(s):

F. A. Faruqi ◽

Susumu Okuda ◽

W. O. Williamson

Keyword(s):

Methylene Blue ◽

Special Reference ◽

Cation Exchange ◽

High Ph ◽

Inorganic Cations ◽

Ph Values ◽

Aqueous Suspensions ◽

Exchange Site

AbstractThe chemisorption of methylene blue by kaolinite crystals increased as the aqueous suspensions changed from acid to alkaline because, at high pH values, not only the basal pinacoids but the edge-faces were negatively charged. The inability to calculate acceptable specific surfaces or cation exchange capacities from the chemisorption data is discussed, with special reference to the orientation of adsorbed dye cations, the covering of more than one exchange site by a monomer or polymer, the different concentrations of exchange sites on the basal pinacoids and edge-faces respectively, the possibility that such sites occur on the tetrahedral rather than on the octahedral basal pinacoid, and the incomplete replacement of inorganic cations.

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Interaction of the Vanadyl(IV) Cation with L-Ascorbic Acid and Related Systems

Zeitschrift für Naturforschung B ◽

10.1515/znb-1998-0220 ◽

1998 ◽

Vol 53 (2) ◽

pp. 256-262 ◽

Cited By ~ 8

Author(s):

E. G. Ferrer ◽

P. A . M. Williams ◽

E. J. Baran

Keyword(s):

Ascorbic Acid ◽

Electronic Spectroscopy ◽

Dehydroascorbic Acid ◽

Solid Complex ◽

Acid Interaction ◽

Ph Values ◽

Spectroscopic Behavior ◽

Solid Complexes

Abstract The interaction of VO2+ with L-ascorbic acid and dehydroascorbic acid was investigated by electronic spectroscopy in solution at different pH values. In the case of ascorbic acid, two different solid complexes containing one or two monodeprotonated ascorbate ligands could be isolated and characterized. With dehydroascorbic acid, interaction begins at pH = 4 but at higher pH values the ligand is hydrolysed irreversibly, generating 2,3-diketogulonic acid. A solid complex containing this ligand could be precipitated at pH = 7. Its spectroscopic behavior confirms the interaction of the cation with an enolised form of the acid.

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Removal of Toxic Congo Red Dye Using Water Hyacinth Petiole, an Efficient and Selective Adsorbent

Journal of the chemical society of pakistan ◽

10.52568/000802/jcsp/41.05.2019 ◽

2019 ◽

Vol 41 (5) ◽

pp. 825-825

Author(s):

Abul Kalam Md Lutfor Rahman Abul Kalam Md Lutfor Rahman ◽

Rajib Al Mamun Rajib Al Mamun ◽

Nafees Ahmed Nafees Ahmed ◽

Aparna Sarkar and Akash Mamon Sarkar Aparna Sarkar and Akash Mamon Sarkar

Keyword(s):

Congo Red ◽

Water Hyacinth ◽

Freundlich Isotherm ◽

Batch Process ◽

Living System ◽

Sodium Chlorite ◽

Order Kinetic ◽

Ph Values ◽

Equilibrium Data ◽

Selective Adsorbent

Congo red (CR), one of the major dyes used in the textile mills of Bangladesh has carcinogenic and chronic effect on living system. Removal of CR was done by using water hyacinth petiole (WHP), an efficient and selective adsorbent. Adsorption experiment was performed through batch process at different pH values, dye concentrations, contact times, particle sizes and dosages of adsorbent. A comparable study was carried out using untreated and sodium chlorite treated WHP at different pH values. Equilibrium adsorption was attained after 240 minutes. The highest removal 94.88% was obtained using sodium chlorite treated water hyacinth petiole (SCT-WH) and 94.51% using untreated water hyacinth petiole (UT-WH) at pH 6. Adsorption increased with the increase of initial dye concentration and after a certain time saturation was attained. Adsorption decreased with the increase of particles size (≤ 75and#181;m, ≤ 150and#181;m and ≤ 300and#181;m) and increased with the amount of adsorbent (0.25g, 0.50g and 0.75g). The equilibrium data were best described by the Freundlich isotherm and adsorption kinetics better fitted to pseudo-second-order kinetic model.

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Surface acidity and basicity of oxide catalysts: From aqueous suspensions to in situ measurements

Kinetics and Catalysis ◽

10.1134/s0023158408060104 ◽

2008 ◽

Vol 49 (6) ◽

pp. 859-867 ◽

Cited By ~ 41

Author(s):

T. S. Glazneva ◽

N. S. Kotsarenko ◽

E. A. Paukshtis

Keyword(s):

Surface Acidity ◽

In Situ Measurements ◽

Oxide Catalysts ◽

Aqueous Suspensions ◽

Acidity And Basicity

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Behaviour of polysulfone ultrafiltration membrane for dyes removal

Water Science & Technology ◽

10.2166/wst.2018.124 ◽

2018 ◽

Vol 77 (8) ◽

pp. 2093-2100 ◽

Cited By ~ 12

Author(s):

A. M. Hidalgo ◽

M. Gómez ◽

M. D. Murcia ◽

M. Serrano ◽

R. Rodríguez-Schmidt ◽

...

Keyword(s):

Congo Red ◽

Textile Industry ◽

Rejection Rate ◽

Ultrafiltration Membrane ◽

Methyl Green ◽

Permeate Flux ◽

Separation Processes ◽

Ph Values ◽

Rejection Coefficient ◽

Limited Application

Abstract Although ultrafiltration membranes have been used for the separation of macromolecules and colloids from solutions, this process has a limited application in the removal of dyes present in coloured discharges of textile industry, as these typically have much lower molecular weight than the molecular cut-off of the membranes (MWCO). In the present work, we have evaluated the behaviour of a polysulfone ultrafiltration membrane in the removal of different dyes from aqueous solutions (Congo red, methyl green and amaranth). Different variables (tangential flow rate, concentration of dye and pH of the feed) were studied to determine their influence on the separation processes (permeate flux and rejection coefficient). The results show that Congo red is easily removed with a GR60PP membrane (MWCO = 25 kDa), whereas methyl green and amaranth show rejection coefficient values of approximately 25.78% and 13.85%, respectively, at neutral pH. Also, an interesting effect is observed for the rejection coefficient for methyl green at different pH values. In addition, several treatments were performed to the membrane so as to modify its surface, trying to improve the values obtained for permeate flux and rejection rate.

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Stabilization of Palygorskite Aqueous Suspensions Using Bio-Based and Synthetic Polyelectrolytes

Polymers ◽

10.3390/polym13010129 ◽

2020 ◽

Vol 13 (1) ◽

pp. 129

Author(s):

Eduardo Ferraz ◽

Luís Alves ◽

Pedro Sanguino ◽

Julio Santarén ◽

Maria G. Rasteiro ◽

...

Keyword(s):

High Speed ◽

Visual Inspection ◽

Colloidal Stability ◽

The Other ◽

Morphological Properties ◽

Ph Values ◽

Aqueous Suspensions ◽

Magnetic Stirring ◽

The Stability ◽

Physical Treatments

Palygorskite is a natural fibrous clay mineral that can be used in several applications, for which colloidal stability in aqueous suspensions is a key point to improve its performance. In this study, methods of magnetic stirring, high-speed shearing, and ultrasonication, as well as different chemical dispersants, combined with these methods, namely carboxymethylcellulose, alginate, polyphosphate, and polyacrylate, were used to improve the dispersibility and the formation of stable suspensions of palygorskite in different conditions of pH. The stability and particle size of suspensions with a low concentration of palygorskite were evaluated by visual inspection, optical and electron microscopy, dynamic light scattering, and zeta potential measurements. Moreover, the palygorskite used in this work was initially characterized for its mineralogical, chemical, physical, and morphological properties. It was found that more stable suspensions were produced with ultrasonication compared to the other two physical treatments, with magnetic stirring being inefficient in all tested cases, and for higher pH values (pH of 12 and pH of 8, the natural pH of the clay) when compared to lower pH values (pH of 3). Remarkably, combined with ultrasonication, carboxymethylcellulose or in a lesser extent polyphosphate at near neutral pH allowed for the disaggregation of crystal bundles of palygorskite into individualized crystals. These results may be helpful to optimize the performance of palygorskite in several domains where it is applied.

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