Water-soluble Organic Dyes Research Articles

Asymmetrically superwetting Janus Double-layer fabric for synchronous oil removal and catalytic reduction of aromatic dyes

Effective synchronized removal of oils and aromatic dyes from wastewater is of great significance for environmental and water rehabilitation. Herein, cotton fabric was first grafted with polyaniline (PANI) nanofibers via a dilute solution polymerization to obtain Fabric@PANI. Utilizing the reversible oxidation-reduction property of PANI, the Fabric@PANI was in-situ oxidized to form superhydrophilic Fabric@PANI@Ag. Afterwards, the Fabric@PANI@Ag was post-modified with octadecanethiol (Thiol) to obtain the superhydrophobic/superoleophilic Fabric@PANI@Ag@Thiol. Notably, the PANI nanofibers as the activated anchored sites could uniformly and robustly immobilize Ag nanoparticles on the fabric. Moreover, a functional superwetting double-layer fabric (DL-Fabric) with asymmetric wettability that consisted of a top Fabric@PANI@Ag layer and a bottom Fabric@PANI@Ag@Thiol layer was prepared, on which immiscible oils can pass through both layers of the DL-Fabric and the water with soluble organic dyes can only wet the top layer. In addition, the water-soluble organic dyes can be reductive degradation using NaBH4 with the assistance of Ag catalysis, achieving simultaneous oil-removal (flux > 2.7 L m−2 s−1, oil rejection > 95%) and in situ catalytic reduction of aromatic dyes (0.01–0.02 M, efficiency > 99.2%). Thus, the versatile functionality of the fabric combined with its facile preparation strategy showed great potential applications in cost-effective water purification.

Toward the Highly Ordered Lamellar Hybrid Membrane for Molecular Sieving by One-Pot Self-Assembly of Hybrid Hyperbranched Polymer

Ordered lamellar hybrid membranes are of great interest, due to their application as functional materials, including molecular sieving, biosensors, optical devices, and drug, as well as gene delive...

Two Zn(II) coordination polymers for highly selective detection of phenol based nitroaromatics and removal of water soluble organic dyes

Two new coordination polymers, namely, [Zn2(ctpy)2(bdc)]n (1) and [Zn(ctpy)(suc)0.5]n (2) (Hctpy ​= ​2,2’:6’2’’-terpyridine-4’-carboxylic acid, H2bdc ​= ​1,4-benzene dicarboxylic acid, H2suc ​= ​succinic acid) have been synthesized under solvothermal condition. Structural analysis reveals that complexes 1 and 2 exhibit 1D ladder chain structures formed with the coordinated Zn(II) and Hctpy as ladder chains and the coordinated H2bdc/H2suc as the bars. The neighbouring chains are further linked by π … π packing to form 2D layer structures. Both the two complexes show highly selective detection of 2,4,6-trinitrophenol, 2,4-dinitrophenol, 4-nitrophenol and 2-nitrophenol from benzene based nitroaromatics (NACs), and efficient removal of Congo Red (CR) from aqueous solution.

A thixotropic supramolecular metallogel with a 2D sheet morphology: iodine sequestration and column based dye separation.

Sequestration of hazardous radioactive iodine and dye separation to reduce industrial waste through reutilization is pivotal for environmental safety. In this regard, herein, the synthesis of a new waterborne ultrasensitive supramolecular metallogel (Mg@DEOA) with a 2D sheet morphology is accomplished through direct mixing of a low molecular weight gelator diethanolamine and magnesium nitrate hexahydrate. This porous metallogel (180 m2 g-1) exhibits thixotropic properties and is injectable. The material was found to be an effective (587 mg g-1) host matrix for iodine sequestration from solution. Moreover, the Mg@DEOA xerogel was used to efficiently remove rhodamine B from a mixture of dyes with high separation factors through a xerogel packed column and as an adsorbent material for water-soluble dyes and CO. This column based application demonstrated by the metallogel could be useful for practical industrial dye-separation.

Colorimetric Chemosensor for Hg2+ Based on Nuclear Fast Red and a Cationic Polyelectrolyte in Aqueous Solution.

We have developed a colorimetric chemosensor based on an anionic organic dye, commercially available nuclear fast red (NFR) and a cationic polyelectrolyte, poly(diallyldimethylammonium chloride) (PDADMAC) for detection of Hg2+ in aqueous solution at physiological conditions. Upon addition of Hg2+, a bathchromic shift in the absorption was observed concomitantly with color change from pink to reddish violet which was easily detectable by the naked eye, while such a change was not observed for NFR alone, indicating that PDADMAC played an important role in detecting Hg2+. This investigation can propose the simple and valuable construction method for a novel chemosensor by mixture of a water-soluble organic dye and an oppositely charged polyelectrolyte.

Response of Optically Transparent pH Sensing Films to Temperature and Temperature Variations

There are numerous applications for thin films based chemical pH sensors, in such areas as biomedical, military, environmental, food, and consumer products. pH sensitive films fabricated through the ionic self-assembled monolayers technique were made of polyelectrolyte polyallylamine hydrochloride and the water-soluble organic dye molecule Direct Yellow 4. The films were monitored in various environmental conditions and for selected periods, at temperatures varying between −13.7 and 46.2 °C. Absorbance measurements and atomic force microscopy performed before and after thermal treatment indicate that for optimized thickness and composition the films maintain their functionality and are not affected by long-term exposure at these temperatures.

Smartphone-based image analysis for evaluation of magnetic textile solid phase extraction of colored compounds

Novel modern easily feasible methods for direct evaluation of a new, simple preconcentration analytical procedure have been developed. Two types of smartphone image analysis applications (ON Color Measure and Color Lab) were evaluated to obtain RGB and HSV color spaces data for the quantification of Magnetic textile solid phase extraction of colored compounds (e.g. water-soluble organic dyes). Both direct measurement of color spaces values via the smartphone camera and image analysis of the photograph can be used successfully. The obtained data were similar to those obtained by previously examined professional ImageJ software. The saturation (S) values of the HSV color space are directly proportional to the concentrations of the analyzed dye.

Methylene blue functionalized graphene as binder-free electrode for high-performance solid state supercapacitors

Electrochemical active small organic molecules are potential electrode materials for supercapacitors due to their sustainable and good redox reversibility. However, the poor electrical conductivity restricts their application in supercapacitors. Herein, a water soluble organic dye of methylene blue (MB) has been supported on graphene (GR) through a facile ultrasonic method to form a methylene blue/graphene (MB/GR) composite. A small amount of MB (13%) in MB/GR composite improves the wettability of GR and supplies pseudocapacitance. The MB/GR composite can be used as a binder-free electrode for supercapacitors, and gives a high specific capacitance of 517 F g−1 at 0.5 A g−1 in 0.5 mol L−1 H2SO4 aqueous electrolyte with a satisfactory capacitive retention of 91% after 2000 consecutive cyclic voltammetry tests at 10 mV s−1. Benefiting from the high specific capacitance of MB/GR composite, the as-assembled symmetrical solid-state supercapacitor (MB/GR//MB/GR) delivers a high energy density of 30.36 Wh kg−1 at 0.7 kW kg−1, and excellent cycle stability (nearly 27% drop after 10,000 consecutive constant current charge-discharge at 5 A g−1). This work offers some enlightenment to design and preparation of high-performance electrode materials for supercapacitors.

Synthesis of Dual-Functional and Robust Underwater Superoleophobic Interfaces.

Fish-scale-mimicked super oil-repelling wettability that functions under water has emerged as an important avenue for developing various functional materials. Mainly, polymeric hydrogel, brittle metal oxides, and electrostatic multilayers have been utilized for synthesizing an artificial underwater superoleophobic interface, and most of these reported artificial bioinspired wettabilities are likely to be compromised under practically relevant severe settings. Moreover, a design of a dual-functional fish-scale-mimicked interface that would be capable of separating water-soluble organic pollutants, in addition to the eco-friendly removal of different forms of contaminated oils under severe settings, could be highly useful in addressing globally recognized severe water pollution problems. In this report, a dual-functional underwater superoleophobic membrane is introduced for simultaneous removal of contaminated dyes and oil/oily phase, where graphene oxide (GO) nanosheets were strategically integrated with naturally abundant and environmentally friendly cotton fibers by adopting mussel-inspired chemistry. The synthesized membrane was found to exhibit fish-scale-mimicked nonadhesive underwater superoleophobicity, and this super oil repellency remained unaffected even after prolonged exposures to various practically relevant harsh chemical and physical conditions. Moreover, this material was capable of rapid (within 2 min) adsorption of water-soluble cationic organic dyes with high adsorption capacity (136 mg/g for methylene blue), following linear pseudo-second-order kinetics. The biomimicked extreme oil repellency was exploited for separating different forms (bulk and emulsion) of oil/oily (both sedimenting and floating) contaminants with high separation efficiency (above 98%), and the immobilized GO in the biomimicked membrane parallely allowed cationic organic dyes (methylene blue and crystal violet) to be removed from the aqueous phase through a single-step gravity-driven filtration process. The performance of simultaneous removal of cationic dyes and oil/oily contaminants remained unaffected even under various practically relevant severe settings including extremes of pH, sea water, river water, and so forth. Furthermore, the dual-functional biomimicked membrane was repetitively (10 times) used for successful separation of both the contaminated cationic dye and oil/oily phase from the aqueous phase, without affecting the separation efficiency. This simple approach is likely to provide a facile basis for addressing the problem of water pollution under practically relevant diverse and severe settings.

Preparation of blue-colored Al@SiO2@(CuPc-SO3)2Ba pigments: Different silane coupling agents on the corrosion resistance properties and color performance

Blue-colored aluminum pigments with double layer structure Al@SiO2@(CuPc-SO3)2Ba were prepared by a two-step process of surface modification. The aluminum pigments were firstly encapsulated using tetraethoxysilane (TEOS) and silane coupling agents as precursors. A kind of water-soluble organic dye CuPc-SO3H was immobilized onto the surface of Al@SiO2 by liquid-phase deposition. SEM, FTIR, XRD and XPS were used to characterize the surface morphology and chemical structure of the Al@SiO2@(CuPc-SO3)2Ba pigments. The effect of different silane coupling agents and optimum conditions on the two-step surface modification were studied. The corrosion results showed that the coupling agent with long alkyl chain could significantly improve corrosion resistance of aluminum pigments. Chromatism analysis indicated that the glossiness of Al@SiO2@(CuPc-SO3)2Ba pigments decreased slightly and showed angle-dependent optical effect.

Competitive Binding of Organic Dyes between Cucurbiturils and Octa Acid.

Employing six cationic water-soluble organic dye molecules as probes, we have attempted to qualitatively understand the factors that govern the attraction between such molecules and the anionic water-soluble host, octa acid (OA). Examination of the competitive host–guest complexation between cucurbit[8]uril (CB[8]) and OA using absorption and emission spectroscopy revealed that the dye molecules included within CB[8] could be “pulled out” by OA. However, an order of magnitude higher concentration of OA was required to shift the equilibrium toward OA, suggesting that attraction between the anionic host OA and the cationic dye molecules such as cresyl violet perchlorate and methylene blue is weaker than the hydrophobic and cation–dipolar interaction between these dye molecules and CB[8]. The importance of Coulombic attraction between OA and dye molecules is also revealed by monomer-to-dimer conversion upon addition of OA to an aqueous solution of monomeric dye molecules. Under conditions where the dye-to-OA ratio is high, freely dissolved monomeric dye molecules are attracted to the exterior of OA and aggregate as dimers on the exterior wall of OA. On the other hand, at high ratios of OA to dye molecules, the dye molecules adsorb as monomers on the exterior of OA. Thus, the monomer-to-dimer ratio in aqueous solution can be controlled by adjusting the ratio of dye to OA molecules. The results presented are of value in qualitatively understanding the relative binding properties of ionic guests with ionic hosts. Studies are qualitative in nature, and further detailed quantitative studies planned for the future are likely to provide deeper understanding of the interaction between water-soluble dye molecules, OA, and CB.

Aldehyde functionalized ionic liquid on electrochemically reduced graphene oxide as a versatile platform for covalent immobilization of biomolecules and biosensing

An aldehyde functionalized ionic liquid, (3-(3-formyl-4-hydroxybenzyl)-3-methylimidazolium hexafluorophosphate) (CHO-IL) has been employed herein as a multiple host platform for the covalent immobilization of mediator as well as enzyme. The CHO-IL was immobilized on electrochemically reduced graphene oxide (ERGO) through the π-π stacking of hydroxybenzyl and imidazolium groups with ERGO and subjected to further covalent attachment of Azure A (Azu-A) mediator or glucose oxidase (GOx) enzyme. Electroactive, water soluble organic dye Azu-A was effectively immobilized to the host IL through simple Schiff base reaction. Azu-A was rendered leak-free in the electrode setup and also responded well for the amperometric determination of H2O2 over a linear range of 0.03–1mM with a detection limit and sensitivity of 11.5µM and 133.2µAmM−1cm−2, respectively. Further, attempts were made to explore the CHO-IL platform for the covalent immobilization of GOx enzyme which served well in retaining the enzyme nativity, reactivity and stability. Under optimized conditions, mediatorless GOx biosensor developed based on direct electrochemistry has exhibited an impressive analytical signal towards glucose detection in the linear range of 0.05–2.4mM with a detection limit and sensitivity of 17µM and 17.7µAmM−1cm−2, respectively. The reliability of the proposed Azu-A based chemical sensor and GOx based biosensor towards the determination of H2O2 and glucose in the real samples have been demonstrated. The remarkable analytical parameters and long term stability of both the sensors could be envisioned as a result of facile immobilization platform and immobilization strategy.

Selective Blocking Property of Microporous Polymer Membranes Fabricated by Chemical Vapor Deposition

Poly-p-xylylene films have been utilized as protective and barrier layers for gases and solvents on electronic and implantable devices. Here we report a new approach to create highly permeable and selective nanofiltration membranes coated with microporous poly-p-xylylene nanofilms fabricated through a dry chemical vapor deposition process by using [2.2]paracyclophanes derivatives on ultrafiltration membranes. The introduction of crosslinking points into rigid poly-p-xylylenes enhanced microporosity and mechanical strength due to insufficient packing and depression of structural relaxation among polymer chains in three-dimensional networks. Crosslinked nanofilms with thicknesses down to 50 nm showed outstanding permeability for water and alcohols at a pressure difference of 0.5 MPa and exhibited higher rejection ratios for water-soluble organic dyes than non-crosslinked nanofilms. Poly-p-xylylene nanofilms also showed an excellent blocking property for non-polar organic solvent permeation through specific interaction of hydrophilic pores with organic solvents.

Catanionic Coacervate Droplets as a Surfactant-Based Membrane-Free Protocell Model.

We report on the formation of surfactant-based complex catanionic coacervate droplets in mixtures of decanoic acid and cetylpyridinium chloride or cetyltrimethylammonium bromide. We show that coacervation occurs over a broad range of composition, pH, and ionic strength. The catanionic coacervates consist of elongated micelles, sequester a wide range of solutes including water-soluble organic dyes, polysaccharides, proteins, enzymes, and DNA, and can be structurally stabilized by sodium alginate or gelatin-based hydrogelation. These results suggest that catanionic coacervates could be exploited as a novel surfactant-based membrane-free protocell model.

Dye Aggregates as New Stabilizers for (Mini)emulsions.

Water-soluble organic dyes such as fluorescein are widely used, mainly for coloration of, e.g., biological samples and groundwater tracing, and they are not obviously amphiphilic by molecular structure like surfactants. Here, we show that the dyes alone stabilize oil-in-water emulsions. Exemplarily, fluorescein is compared with the classical surfactant sodium dodecyl sulfate (SDS) by means of surface/interfacial tension, concentration of stabilizer and electrolyte, as well as pH. The principle can be extended to further classes of water-soluble dyes, which keep up with or exceed SDS by efficiency. Various organic liquids of different polarities can be employed and be polymerized in the case of styrene as disperse phase. Thus, surfactant free latex solely stabilized by water-soluble dyes is accessible. The emulsions can be destabilized by absorption of the dyes to hydrogels, and their complete removal is easily followed visually. The stabilization mechanisms are different for SDS and the dyes: The latter stabilize droplets not as monomers but by their aggregates as molecular scale Pickering stabilizers, which is a new concept of stabilization.

Removal of dyes by adsorption on magnetically modified activated sludge

The ability of magnetically modified activated sludge affected by thermal treatment to remove water-soluble organic dyes was examined. Twelve different dyes were tested. Based on the results of the initial sorption study, four dyes (namely aniline blue, Nile blue, Bismarck brown Y and safranin O) were chosen for further experiments due to their promising binding onto magnetic activated sludge. Significant factors influencing adsorption efficiency such as dependence of contact time, initial pH or temperature were studied in detail. The adsorption process was very fast; more than 88 % of dye content (55 mg/L) was adsorbed within 15 min under experimental conditions used. The equilibrium adsorption data were analyzed by Freundlich, Langmuir and Sips adsorption isotherm models, and the fitting of each isotherm model to experimental data was assessed on the basis of error functions. The maximum adsorption capacities of magnetic activated sludge were 768.2, 246.9, 515.1 and 326.8 mg/g for aniline blue, Bismarck brown Y, Nile blue and safranin O, respectively. The kinetic studies indicated that adsorption of all selected dyes could be well described by the pseudo-second-order kinetic model, and the thermodynamic data suggested the spontaneous and endothermic process.

Magnetically modified Posidonia oceanica biomass as an adsorbent for organic dyes removal

Magnetically modified Posidonia oceanica sea grass dead biomass was employed as an adsorbent of organic dyes. The adsorption of seven water-soluble organic dyes was characterized using Langmuir adsorption model. The highest calculated maximum adsorption capacity was found for Bismarck brown Y (233.5 mg g-1), while the lowest capacity value was obtained for safranin O (88.1 mg g-1). The adsorption processes followed the pseudo-second-order kinetic model and the thermodynamic studies indicated spontaneous and endothermic adsorption.

Sonochemically Synthesized Beta-Cyclodextrin Functionalized Graphene Oxide and its Efficient Role in Adsorption of Water Soluble Brilliant Green Dye

In this short communication, we report a novel and inexpensive approach to synthesize Beta-Cyclodextrin functionalized Graphene Oxide (GOCD) which has been fabricated for the adsorption of water soluble organic dyes from aqueous solution. The adsorbent GOCD has been synthesized using facile sonochemical route and accordingly characterized using techniques such FTIR, TGA, RAMAN and TEM respectively. Brilliant green dye (BG), a cationic, water soluble dye, commonly used as green pigment in textile/dye printing technology, is a highly toxic compound and consequently GOCD has been employed for its removal before recyclability of the waste water. The adsorption study of BG onto GOCD is investigated using UV-vis absorption spectroscopy. The exploration established the fact that the as-synthesized material GOCD has appreciable capability in dye removal and therefore possesses significant roles in waste water treatment technology.

One-Pot Synthesis of Cy5-Encapsulated Photostable Fluorescent Silica Nanoparticles for Bioimaging

A new type of Cy5-encapsulated photostable fluorescent silica nanoparticles (FSNPs) bearing positive charges have been successfully fabricated by a reverse microemulsion synthesis in one-pot. The Cy5 dye containing four primary amines are embedded into silica via covalent bonds through a silane coupling agent (GPTMS), followed by co-condensation with tetraethylorthosilicate. The uniform-sized, spherical and monodispersed FSNPs have high fluorescence intensity and photostability. The FSNPs exhibit high stability, good biocompatibility as well as low cytotoxicity. These FSNPs can be internalized into live cells and thus fluorescently label the cells. This study provides a simple synthesis approach that can be applied to other water-soluble and amino-modified organic dye molecules for biological targeting and fluorescent cell imaging.

γ-Fe2O3 modified with C-18 carboxylic acids: A magnetic carrier for immobilized organic compounds

Ferromagnetic γ-Fe2O3 was modified with stearic and oleic acids. Diffuse reflection spectra show that modification occurs both via the interaction with free surface hydroxyl groups and by forming bidentate carboxylates with iron atoms. Surface modification enhances adsorption of water-soluble organic dyes (orange acid and methylene blue dyes, cytochrome C enzyme) due to contribution of hydrophobic interaction to adsorption. Differences in adsorption of dyes onto the modified γ-Fe2O3 caused by different structures of hydrocarbon chains in stearic and oleic acids were revealed. The effect of electrolyte concentration and pH of a solution on adsorption of cytochrome C was studied. The activated iron(III) oxide can be used as a magnetic carrier for immobilized enzymes in bioreactors and for targeted drug delivery.