Research

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1206 KiB

Open AccessArticle

Fractional Factorial Design Study on the Performance of GAC-Enhanced Electrocoagulation Process Involved in Color Removal from Dye Solutions

by Marius Sebastian Secula, Igor Cretescu, Benoit Cagnon, Liliana Rozemarie Manea, Corneliu Sergiu Stan and Iuliana Gabriela Breaban

Materials 2013, 6(7), 2723-2746; https://doi.org/10.3390/ma6072723 - 10 Jul 2013

Cited by 63 | Viewed by 8170

Abstract

The aim of this study was to determine the effects of main factors and interactions on the color removal performance from dye solutions using the electrocoagulation process enhanced by adsorption on Granular Activated Carbon (GAC). In this study, a mathematical approach was conducted [...] Read more.

The aim of this study was to determine the effects of main factors and interactions on the color removal performance from dye solutions using the electrocoagulation process enhanced by adsorption on Granular Activated Carbon (GAC). In this study, a mathematical approach was conducted using a two-level fractional factorial design (FFD) for a given dye solution. Three textile dyes: Acid Blue 74, Basic Red 1, and Reactive Black 5 were used. Experimental factors used and their respective levels were: current density (2.73 or 27.32 A/m²), initial pH of aqueous dye solution (3 or 9), electrocoagulation time (20 or 180 min), GAC dose (0.1 or 0.5 g/L), support electrolyte (2 or 50 mM), initial dye concentration (0.05 or 0.25 g/L) and current type (Direct Current—DC or Alternative Pulsed Current—APC). GAC-enhanced electrocoagulation performance was analyzed statistically in terms of removal efficiency, electrical energy, and electrode material consumptions, using modeling polynomial equations. The statistical significance of GAC dose level on the performance of GAC enhanced electrocoagulation and the experimental conditions that favor the process operation of electrocoagulation in APC regime were determined. The local optimal experimental conditions were established using a multi-objective desirability function method. Full article

(This article belongs to the Special Issue Advances in Colorants)

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2041 KiB

Open AccessArticle

Density Functional Theory (DFT) Study of Coumarin-based Dyes Adsorbed on TiO₂ Nanoclusters—Applications to Dye-Sensitized Solar Cells

by Corneliu I. Oprea, Petre Panait, Fanica Cimpoesu, Marilena Ferbinteanu and Mihai A. Gîrţu

Materials 2013, 6(6), 2372-2392; https://doi.org/10.3390/ma6062372 - 10 Jun 2013

Cited by 72 | Viewed by 10586

Abstract

Coumarin-based dyes have been successfully used in dye-sensitized solar cells, leading to photovoltaic conversion efficiencies of up to about 8%. Given the need to better understand the behavior of the dye adsorbed on the TiO₂ nanoparticle, we report results of density functional [...] Read more.

Coumarin-based dyes have been successfully used in dye-sensitized solar cells, leading to photovoltaic conversion efficiencies of up to about 8%. Given the need to better understand the behavior of the dye adsorbed on the TiO₂ nanoparticle, we report results of density functional theory (DFT) and time-dependent DFT (TD-DFT) studies of several coumarin-based dyes, as well as complex systems consisting of the dye bound to a TiO₂ cluster. We provide the electronic structure and simulated UV-Vis spectra of the dyes alone and adsorbed to the cluster and discuss the matching with the solar spectrum. We display the energy level diagrams and the electron density of the key molecular orbitals and analyze the electron transfer from the dye to the oxide. Finally, we compare our theoretical results with the experimental data available and discuss the key issues that influence the device performance. Full article

(This article belongs to the Special Issue Advances in Colorants)

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1074 KiB

Open AccessArticle

Characterization of Natural Dyes and Traditional Korean Silk Fabric by Surface Analytical Techniques

by Jihye Lee, Min Hwa Kang, Kang-Bong Lee and Yeonhee Lee

Materials 2013, 6(5), 2007-2025; https://doi.org/10.3390/ma6052007 - 15 May 2013

Cited by 35 | Viewed by 9380

Abstract

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) are well established surface techniques that provide both elemental and organic information from several monolayers of a sample surface, while also allowing depth profiling or image mapping to be carried out. The [...] Read more.

Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) are well established surface techniques that provide both elemental and organic information from several monolayers of a sample surface, while also allowing depth profiling or image mapping to be carried out. The static TOF-SIMS with improved performances has expanded the application of TOF-SIMS to the study of a variety of organic, polymeric and biological materials. In this work, TOF-SIMS, XPS and Fourier Transform Infrared (FTIR) measurements were used to characterize commercial natural dyes and traditional silk fabric dyed with plant extracts dyes avoiding the time-consuming and destructive extraction procedures necessary for the spectrophotometric and chromatographic methods previously used. Silk textiles dyed with plant extracts were then analyzed for chemical and functional group identification of their dye components and mordants. TOF-SIMS spectra for the dyed silk fabric showed element ions from metallic mordants, specific fragment ions and molecular ions from plant-extracted dyes. The results of TOF-SIMS, XPS and FTIR are very useful as a reference database for comparison with data about traditional Korean silk fabric and to provide an understanding of traditional dyeing materials. Therefore, this study shows that surface techniques are useful for micro-destructive analysis of plant-extracted dyes and Korean dyed silk fabric. Full article

(This article belongs to the Special Issue Advances in Colorants)

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443 KiB

Open AccessCommunication

The Development of Novel Near-Infrared (NIR) Tetraarylazadipyrromethene Fluorescent Dyes

by Sung-Chan Lee, Duanting Zhai, Parag Mukherjee and Young-Tae Chang

Materials 2013, 6(5), 1779-1788; https://doi.org/10.3390/ma6051779 - 06 May 2013

Cited by 9 | Viewed by 7492

Abstract

Novel structures of an near-infrared (NIR) tetraarylazadipyrromethene (aza-BODIPY) series have been prepared. We designed the core structure containing two amido groups at the para-position of the aromatic rings. The amido group was incorporated to secure insensitivity to pH and to ensure a bathochromic [...] Read more.

Novel structures of an near-infrared (NIR) tetraarylazadipyrromethene (aza-BODIPY) series have been prepared. We designed the core structure containing two amido groups at the para-position of the aromatic rings. The amido group was incorporated to secure insensitivity to pH and to ensure a bathochromic shift to the NIR region. Forty members of aza-BODIPY compounds were synthesized by substitution of the acetyl group with commercial amines on the alpha bromide. The physicochemical properties and photostability were investigated and the fluorescence emission maxima (745~755 nm) were found to be in the near infrared (NIR) range of fluorescence. Full article

(This article belongs to the Special Issue Advances in Colorants)

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Review

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304 KiB

Open AccessReview

Dye Sensitizers for Photodynamic Therapy

by Alexandra B. Ormond and Harold S. Freeman

Materials 2013, 6(3), 817-840; https://doi.org/10.3390/ma6030817 - 06 Mar 2013

Cited by 684 | Viewed by 23023

Abstract

Photofrin^® was first approved in the 1990s as a sensitizer for use in treating cancer via photodynamic therapy (PDT). Since then a wide variety of dye sensitizers have been developed and a few have been approved for PDT treatment of skin and [...] Read more.

Photofrin^® was first approved in the 1990s as a sensitizer for use in treating cancer via photodynamic therapy (PDT). Since then a wide variety of dye sensitizers have been developed and a few have been approved for PDT treatment of skin and organ cancers and skin diseases such as acne vulgaris. Porphyrinoid derivatives and precursors have been the most successful in producing requisite singlet oxygen, with Photofrin^® still remaining the most efficient sensitizer (quantum yield = 0.89) and having broad food and drug administration (FDA) approval for treatment of multiple cancer types. Other porphyrinoid compounds that have received approval from US FDA and regulatory authorities in other countries include benzoporphyrin derivative monoacid ring A (BPD-MA), meta-tetra(hydroxyphenyl)chlorin (m-THPC), N-aspartyl chlorin e6 (NPe6), and precursors to endogenous protoporphyrin IX (PpIX): 1,5-aminolevulinic acid (ALA), methyl aminolevulinate (MAL), hexaminolevulinate (HAL). Although no non-porphyrin sensitizer has been approved for PDT applications, a small number of anthraquinone, phenothiazine, xanthene, cyanine, and curcuminoid sensitizers are under consideration and some are being evaluated in clinical trials. This review focuses on the nature of PDT, dye sensitizers that have been approved for use in PDT, and compounds that have entered or completed clinical trials as PDT sensitizers. Full article

(This article belongs to the Special Issue Advances in Colorants)

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779 KiB

Open AccessReview

Solubilization of Hydrophobic Dyes in Surfactant Solutions

by Ali Reza Tehrani-Bagha and Krister Holmberg

Materials 2013, 6(2), 580-608; https://doi.org/10.3390/ma6020580 - 21 Feb 2013

Cited by 223 | Viewed by 19328

Abstract

In this paper, the use of surfactants for solubilization of hydrophobic organic dyes (mainly solvent and disperse dyes) has been reviewed. The effect of parameters such as the chemical structures of the surfactant and the dye, addition of salt and of polyelectrolytes, pH, [...] Read more.

In this paper, the use of surfactants for solubilization of hydrophobic organic dyes (mainly solvent and disperse dyes) has been reviewed. The effect of parameters such as the chemical structures of the surfactant and the dye, addition of salt and of polyelectrolytes, pH, and temperature on dye solubilization has been discussed. Surfactant self-assemble into micelles in aqueous solution and below the concentration where this occurs—the critical micelle concentration (CMC)—there is no solubilization. Above the CMC, the amount of solubilized dye increases linearly with the increase in surfactant concentration. It is demonstrated that different surfactants work best for different dyes. In general, nonionic surfactants have higher solubilization power than anionic and cationic surfactants. It is likely that the reason for the good performance of nonionic surfactants is that they allow dyes to be accommodated not only in the inner, hydrocarbon part of the micelle but also in the headgroup shell. It is demonstrated that the location of a dye in a surfactant micelle can be assessed from the absorption spectrum of the dye-containing micellar solution. Full article

(This article belongs to the Special Issue Advances in Colorants)

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212 KiB

Open AccessReview

A Review of Aspects of Oxidative Hair Dye Chemistry with Special Reference to N-Nitrosamine Formation

by David Lewis, John Mama and Jamie Hawkes

Materials 2013, 6(2), 517-534; https://doi.org/10.3390/ma6020517 - 13 Feb 2013

Cited by 29 | Viewed by 15876

Abstract

This review discusses a new aspect to the safety profile of oxidative hair dyes using data already in the public domain. These dyes contain secondary amines that are capable of forming potentially carcinogenic nitrosamine derivatives when exposed to atmospheric pollution. Numerous scientific articles [...] Read more.

This review discusses a new aspect to the safety profile of oxidative hair dyes using data already in the public domain. These dyes contain secondary amines that are capable of forming potentially carcinogenic nitrosamine derivatives when exposed to atmospheric pollution. Numerous scientific articles confirm the existence of secondary amines in hair dyes (and their intermediates), the possibility of nitrosation by atmospheric NO_x of secondary amines to give the N-nitrosamines, and the significant safety risks on N-nitrosamines. It is believed that such nitrosamine derivatives should be investigated more fully in the interests of consumer safety. Full article

(This article belongs to the Special Issue Advances in Colorants)

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935 KiB

Open AccessReview

Organic and Inorganic Dyes in Polyelectrolyte Multilayer Films

by Vincent Ball

Materials 2012, 5(12), 2681-2704; https://doi.org/10.3390/ma5122681 - 10 Dec 2012

Cited by 17 | Viewed by 6923

Abstract

Polyelectrolyte multilayer films are a versatile functionalization method of surfaces and rely on the alternated adsorption of oppositely charged species. Among such species, charged dyes can also be alternated with oppositely charged polymers, which is challenging from a fundamental point of view, because [...] Read more.

Polyelectrolyte multilayer films are a versatile functionalization method of surfaces and rely on the alternated adsorption of oppositely charged species. Among such species, charged dyes can also be alternated with oppositely charged polymers, which is challenging from a fundamental point of view, because polyelectrolytes require a minimal number of charges, whereas even monovalent dyes can be incorporated during the alternated adsorption process. We will not only focus on organic dyes but also on their inorganic counterparts and on metal complexes. Such films offer plenty of possible applications in dye sensitized solar cells. In addition, dyes are massively used in the textile industry and in histology to stain textile fibers or tissues. However, the excess of non bound dyes poses serious environmental problems. It is hence of the highest interest to design materials able to adsorb such dyes in an almost irreversible manner. Polyelectrolyte multilayer films, owing to their ion exchange behavior can be useful for such a task allowing for impressive overconcentration of dyes with respect to the dye in solution. The actual state of knowledge of the interactions between charged dyes and adsorbed polyelectrolytes is the focus of this review article. Full article

(This article belongs to the Special Issue Advances in Colorants)

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