Dye In Aqueous Medium Research Articles

Green Synthesis of CoFe2O4 and Investigation of its Catalytic Efficiency for Degradation of Dyes in Aqueous Medium

Abstract The catalytic wet oxidation is one the methods used for elimination of dyes from aqueous medium in which various metal based materials can be used as heterogeneous catalysts. Bimetallic oxides as heterogeneous catalysts have gained much attention as bimetallization improve the catalytic properties of the resulting particles. The biosynthetic green method is the most viable and simple method for synthesis of bimetallic oxides nanoparticles. Here, we report the green synthesis of CoFe2O4 particles using Azadirachata indica leaves extract as reducing and stabilizing agent. The synthesized particles were characterized using X-ray diffraction, thermogravimetric analysis, Fourier-transform infrared spectroscopy and scanning electron microscopy. The synthesized CoFe2O4 particles were tested as a catalyst for mineralization of rhodamine B and methylene blue dyes in the presence of hydrogen peroxide in aqueous media. More than 95% dyes degraded in 120 min. The reaction kinetics was described in terms of Langmuir–Hinshelwood mechanism which suggests that molecules of dye and hydrogen peroxide adsorbed surface of CoFe2O4 and then react together.

Synthesis a novel multilamellar mesoporous TiO2/ZSM-5 for photo-catalytic degradation of methyl orange dye in aqueous media

TiO2 photocatalyst hybridized with new multilamellar vesicles (MLVs) mesoporous ZSM-5 substrate (TiO2/ZSM-5) were prepared by the direct templating technique for decolorization and minerlization of methyl orange (MO) dye effluent. The synthesized materials were characterized by X-ray diffraction (XRD), Field-emission scanning electron microscopy (FE-SEM), Fourier-transformed infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET). It was found that the specific surface area (SBET) of the synthesized TiO2/ZSM-5 was 1151m2g−1. The results also indicated that the zeolite structure conserves mesoporous structure after the removal of surfactant templates. Several parameters were also investigated such as the effect of catalyst types, pH, adsorption/photocatalysis phenomenon and contact time. Under 180min solar irradiation, MO dye was efficiently decolorized and mineralized to be 99.55% and 99%, respectively, at an initial MO concentration of 20mgL−1. Furthermore, the photocatalysis kinetic fit the pseudo-second-order model well and a great potential for saving energy associated with its recyclability. Therefore, the synthesized TiO2/ZSM-5 could be used as a promosing photocatalysis for fast removal and treatment of coloured wastewater.

Immobilized Nanoparticles on Polymeric Carriers for Removal of Reactive Textile Dyes in Aqueous Media

In the waste water treatment, especially in the removal of textile dyes from aqueous media, it is known that photocatalytic oxidation technique has tremendous advantages compared to conventional techniques, such as quick oxidation, prevention of polycyclic end products, and oxidation of organic species even at µg/L concentrations. Heterogeneous photocatalysis consisting semiconductor oxides such as TiO 2 has been effectively implemented in aqueous media. However, problems such as catalyst separation and catalyst recovery are encountered when powder catalysts are used. Meanwhile, the fixation of oxides by any method reduces the catalytic effıciency. In this study, nanoparticles (10-100 nm) as heterogeneous catalysts were synthesized and then immobilized onto cross-linked polymer carriers that are able to swell in aqueous media in order to increase photocatalytic activity to the highest level. It has been seen that the removal of textile dyes is possible by means of nanoparticles immobilized onto cross-linked polymer carriers. The performance of photocatalyst was evaluated in the removal of reactive textile dye (Acid Red 14) from aqueous media.

Adsorption of procion red using layer double hydroxide Mg/Al

Layer double hydroxide Mg/Al was synthesized by inorganic synthetic method. Material was characterized using FTIR and XRD analyses and used as adsorbent of procion red dye in aqueous medium. Factors that affect the adsorption process are adsorption time as the kinetic parameter; and the temperature and concentration of procion red as the thermodynamic parameter. FTIR spectra of layer double hydroxides showed unique vibration at wavenumber 1300 cm -1 and 1600 cm -1 . Characterization using XRD shows diffraction angles at 29 o , 27 o , and 28 o , which are typical of Mg/Al double layer hydroxides. Adsorption of procion red using layer double hydroxide Mg/Al resulted adsorption rate 7.1 minutes -1 , maximum adsorption capacity 111.1 mg/g at 60 o C with increasing energy by increasing adsorption temperature. Keywords: Layered double hydroxides, adsorption, procion red.

Using Natural Stone Pumice in Van Region on Adsorption of Some Textile Dyes

T oxic effect of textile dyes their increasing quantities in air, soil and water environments, because of growing of industrial actives, they must be taken into consideration since they harm to environment. We come across textile dyes in natural wetlands as result of uncontrolled industrial wasted. Textile dyes that can accumulate easily in their environments may show toxic effects. Pumice, accruing as result of volcanic events and durable against chemical factors, is a rock that has porous structure. Pumices have a porous structure because of sudden cooling of the rock and sudden leaving of gases a result of volcanic events. Thanks to these pores, pumices heat and sound insulation are quite high. The most distinctive feature of pumice from other rocks is that it has different colors and there is not crystal water in its porous structure. Adsorption studies are applied with Van Pumice at pH = 6, the adsorption mechanism and changing metal concentration. As result of these researches, it has been found that there are different adsorption movements at pH 6 between textile dyes and Van Pumice. The result of this study shows that the Pumice found in Lake Van gives a better fit for the Langmuir Isotherm (model) and the amount of adsorption increases with the temperature. It is thereby concluded that the Pumice located in Lake Van is a recommended adsorbent for filtering the used textile dye in aqueous medium.

New pyrazole based single precursor for the surfactantless synthesis of visible light responsive PbS nanocrystals: Synthesis, X-ray crystallography of ligand and photocatalytic activity

A pyrazole based heterocyclic compound methyl 3, 5-dimethyl-3-(N′-methylsulfanylthio- carbonyl-hydrazino)-2,3-dihydro-pyrazole-1-carbodithioate (Hmdpc) and [Pb(mdpc)2] have been synthesized and characterized to obtain nanosized visible light responsive PbS nanocrystals (NCs). The presence of four–SCH3 groups in each Pb(II)-center in the SP controls the shape and size of the nanocrystals. A possible growth mechanism based on internal molecular transfer of thiol group for the preparation of spherical nanocrystals has been proposed. The synthesized PbS NCs were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution TEM (HRTEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). The optical properties of the nanocrystals reveal the absorption in the entire visible region and can play significant role in showing photocatalytic activity. The PbS nanocrystals show prominent catalytic activity against degradation of Rose Bengal (RB) dyes in aqueous medium in presence of visible light.

MgFe2O4-Fe2O3 heterostructured nanomaterials: Synthesis and photocatalytic study

MgFe2O4-Fe2O3 composites nanostructures were synthesized by different wet chemical methods such as: precipitation, reflux and hydrothermal method. XRD confirmed the formation of composite MgFe2O4-Fe2O3 phase by precipitation, reflux methods and single MgFe2O4 phase by hydrothermal method with well crystalline nature. From FTIR study, the shifting of adsorption bands of metal-oxygen bond corresponding to the vibration of tetrahedral and octahedral complexes of MgFe2O4-Fe2O3 composites was observed than single MgFe2O4 phase. From FESEM images, it is observed that the MgFe2O4-Fe2O3 nanocomposites prepared by precipitation method contains very smooth particles with average diameters around 20–40nm, the MgFe2O4-Fe2O3 nanocomposites prepared by reflux method contains both uniform microspheres and flower-like hierarchical nanostructures with thickness around 100–200nm and the MgFe2O4 nanomaterials synthesized by hydrothermal method contains irregular spherical nanoparticles with diameter around 60–100nm. The prepared nanomaterials were used as photocatalysts to degrade methylene blue dye in aqueous media under solar light irradiation. The MgFe2O4-Fe2O3 nanocomposite prepared by precipitation method was regarded as a superb photocatalyst; 0.1g of the photocatalyst performed the degradation of 99.9% of methylene blue dye from 100ml of 10mg/L solution within 120mins of irradiation time.

Environmentally benign Fe(III)\u2013montmorillonite for rapid adsorption of methylene blue dye in aqueous medium under ambient conditions

Herein we have explored the highly efficient and environmentally benign clay mineral, Fe(III)–montmorillonite [Fe(III)–Mt], for adsorption of methylene blue (MB) dye from aqueous solution under ambient conditions. The Fe(III)–Mt was interacted with MB dye solution at different pH, temperature and solid-to-liquid ratio. The concentration of MB dye removal was estimated from its optical density at λmax = 665 nm using UV–Vis spectrophotometer. The MB dye removal was rapid at basic pH and increases with temperature up to 40 °C. A complete reduction (100%) was occurred in about 7 min at pH 7 and 10 while at pH 3 in about 10 min. The time taken for complete reduction at 0, 30 and 40 °C are 10, 7 and 5 min respectively. The removal followed by adsorption of dye molecules on the spent clay mineral was evident from FESEM/EDX analysis. More importantly, Fe(III)–Mt could be separated and retrieved easily after the reaction by centrifugation from the degraded MB dye solution. The experimental results of MB dye removal from Fe(III)–Mt follows the pseudo first order kinetics. This study reveals that Fe(III)–Mt has the potential to be used as reductant/adsorbant to remove cationic pollutants effectively and rapidly from drinking water and large scale of industrial wastewater.

Sonophotocatalytic degradation of Orange II dye using low cost photocatalyst

The photocatalytic and sonophotocatalytic degradation of Orange II was investigated using a synthesized catalyst with low cost materials. Iron (III) oxide-titanium (IV) oxide (1% Fe) photocatalyst was synthesized by sol-gel method and pure titanium dioxide was used as photocatalytic reference material. Their crystallographic structures were determined by X-ray diffraction. The surface area and pore diameter was studied by Brunauer–Emmett–Teller method (N2 adsorption/desorption). The samples were characterized by Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Analysis (EDX). SEM images show the formation of particles with spherical geometry. Synergistic effects of ultrasound and photocatalysis were demonstrated. Three different ultrasonic frequencies were tested 250 kHz, 500 kHz and 1000 kHz. The best catalytic activity (higher Orange II degradation efficiency) was obtained at 500 kHz. Test results show that it is possible the total decolourisation of the Orange II dye in aqueous media by the sonophotocatalytic process using visible light, without producing hazardous by-products. The process can be considered as a potential environmentally friendly technique for organic synthetic dyes degradation.

A comparative spectroscopic study of thiourea effect on the photophysical and molecular association behavior of various phenothiazine dyes

This paper describes the role of a structure breaking additive (thiourea) on the photophysical and molecular association of a series of phenothiazine dyes in aqueous media using the absorption and fluorescence spectroscopic methods for the first time. The studied dyes were thionine, azure A, azure B, toluidine blue, and methylene blue. The spectral data were analyzed using DECOM program. Relevant spectral parameters in the dye solutions were estimated and discussed based on the chemical structure of the additive and excitonic treatment. The observation of spectral changes in the spectral data of the (water-additive-dye) system indicates the possible structure formation between the dye and additive molecules. However, it is found that in the high concentrations of thiourea the dimer geometries (H- and J-type dimers) are influenced by the dye-additive interactions. As a result, a competition between the dye-additive and dye-dye interactions was also observed.

Synthesis and Characterization of Zinc Oxide and Evaluation of its Catalytic Activities for Oxidative Degradation of Rhodamine B Dye in Aqueous Medium

Abstract We herein report the synthesis of zinc oxide and evaluation of its catalytic performance for degradation of Rhodamine B dye in aqueous medium. Sodium hydroxide and zinc acetate dihydrate were used as precursor materials for synthesis of zinc oxide catalyst. X-ray difractometry, Fourier transform infer red spectroscopy, scanning electron microscopy, thermogravimetric and surface area analyses were used as characterization techniques. Catalytic performance of prepared zinc oxide was evaluated for degradation of Rhodamine B dye in aqueous medium. Catalytic degradation of dye was taking place according to Eley-Rideal mechanism which states that oxygen adsorbed at the surface of ZnO reacts with dye in fluid phase. During the reaction, reactive radicals are formed as a result of electron-hole pair formation between conduction and valence band of zinc oxide catalyst which degrade the dye into water and carbon dioxide.

Bis(thiadiazole)quinoxaline- and bis(thiadiazole)phenanthroquinoxaline-based donor–acceptor type dyes showing simultaneous emission efficiency and color changes from molecular aggregation and twisted intramolecular charge transfer

The development of light emitting systems that exhibit turn-on type emission changes and ratiometric emission color changes is important for biological imaging applications. In this paper, we report that turn-on-type double emission changes and ratiometric emission color changes can be achieved simultaneously by exploiting the aggregation of V-shaped bis(thiadiazolo)quinoxaline- and bis(thiadiazole)phenanthroquinoxaline-triphenylamine donor–acceptor type dyes in aqueous media. When the water fraction of THF/water media in which the dyes were placed was increased, the initial red emission of the monomer state changed to an orange emission in the aggregated state via the quenching of near-infrared emissions. This unusual double emission change was attributed to the combined effect of aggregation and twisted intramolecular charge-transfer.

Investigation of equilibrium, kinetics and thermodynamics of extracted chitin from shrimp shell in reactive blue 29 (RB-29) removal from aqueous solutions

The presence of reactive dyes in aqueous medium cause many problems; therefore, it is necessary to reduce its content in industrial effluents before their discharge into environment. The aim of this study was to investigate the removal of reactive blue 29 (RB-29) dye from aqueous solutions using extracted chitin from shrimp shells as an adsorbent. This study was conducted in a batch experimental system. After extraction of chitin from shrimp shells, the effects of different variables such as pH, RB-29 concentration, contact time and adsorbent dose were investigated. Furthermore, adsorption isotherms, thermodynamics and kinetics of the process were also studied. The results of this study showed that the maximum adsorption capacity (q(max)) of chitin was 116.07 mg/g at a RB-29 concentration of 50 mg/L and contact time of 90 min. In addition, the maximum adsorption was observed at pH = 3 and adsorbent dosage of 0.2 g/L. The experimental data showed that the results were consistent with the Langmuir isotherm model. According to the results of thermodynamic study, standard entropy change Delta S is equal to 25.40 J/mol K, standard enthalpy change Delta H is equal to 7,054.39 J/mol and standard Gibbs free energy values (Delta G) were negative, that represents a spontaneous and endothermic process of RB-29 adsorption by the extracted chitin. Moreover, adsorption kinetics followed the pseudo-second-order kinetic model. Based on the results of this study it can be concluded that chitin can efficiently remove RB-29 dye from aqueous solutions. Keywords Author Keywords:Reactive blue 29; Chitin; Adsorption; Isotherms; Thermodynamics; Kinetics

Well-defined copolymers synthesized by RAFT polymerization as effective modifiers to enhance the photocatalytic performance of TiO2

Αbstract The enhancement of the photocatalytic performance of anatase TiO2 nanoparticles is demonstrated by a facile route, involving their in-situ surface modification with preformed polymer chains. Random copolymers of poly(ethylene glycol) methyl ether acrylate-co-methacrylic acid (PEGA-co-MAA) or poly(ethylene glycol) methyl ether acrylate-co-dopamine methacrylamide (PEGA-co-DMA) were synthesized by reversible addition−fragmentation chain-transfer (RAFT) polymerization and were bound onto the surface of anatase titania nanoparticles via the “grafting to” method. The hybrid nanocatalysts were characterized by fourier transform infrared spectroscopy, zeta-potential measurements, X-ray powder diffraction, thermogravimetric analysis and transmission electron microscopy. Their photocatalytic performance was evaluated by the decoloration of methylene blue (MB) dye in aqueous media under UV–vis light irradiation. The enhanced photoactivity and reusability of the polymer modified photocatalysts compared to that of bare TiO2 nanoparticles was attributed to their improved dispersability and colloidal stability, the smaller particle size that leads to a larger surface area and the increased adsorption capacity of the dye onto the polymer modified nanoparticles.

Native, acidic pre-treated and composite clay efficiency for the adsorption of dicationic dye in aqueous medium.

Environmental applications of composites have attracted the interests of researchers due to their excellent adsorption efficiency for pollutants. Native, HCl pre-treated clay and MnFe2O4/clay composite were investigated as an adsorbent for removal of methyl green from aqueous solution. The adsorption behaviors of dye onto native, HCl pre-treated and composite clays were studied as a function of contact time, adsorbent dose, pH, initial dye concentration and temperature. Maximum dye adsorption of 44 mg/g was achieved at pH of 8, contact time 40 min, adsorbent dose 0.20 g/L and initial dye concentration of 125 mg/L using clay composite. The Langmuir isotherm and pseudo-second-order kinetic model best explained the methyl green dye adsorption onto clay adsorbents. Thermodynamic parameters revealed the endothermic and spontaneous adsorption nature of dye. From results, it is concluded that clay has potential for adsorbing methyl green and can be used for the removal of dyes from industrial effluents.

Influence of calcination temperature on the photocatalytic property of Fe–Cu–ZnO/graphene under visible light irradiation

Fe–Cu–ZnO/graphene composites are prepared by sol-gel method. The influence of the calcination temperature on the catalytic performance of Fe–Cu–ZnO/graphene composites has been studied and their physicochemical properties are characterized via X-ray diffraction (XRD), fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), thermogravimetry-differential scanning calorimetry (TG-DSC) and UV-Vis diffuse reflectance spectra (UV–Vis–DRS). The results show that Fe–Cu–ZnO/graphene composite calcined at 400°C exhibits the highest photocatalytic activity and the degradation rate of dark green dye in aqueous medium achieves 99.28% under exposure of visible light irradiation. The zinc species in the catalyst calcined at 400°C are all converted to the hexagonal wurtzite structures, and Cu2+ and Fe3+ are substituted ions in Zn2+ sites or incorporated into interstitial sites in the ZnO lattice which broaden the spectral response range to visible light. Meanwhile, the electrical properties of graphene are excellent which contribute to the enhanced charge carrier separation, extended light absorption, and increased surface hydroxyl groups. In addition, the catalyst is found to be relatively high reusable.

Optical, phonon and efficient visible and infrared photocatalytic activity of Cu doped ZnS micro crystals

We report, the enhanced photocatalytic behaviour of Cu doped ZnS micro crystals. ZnS and different concentrations of Cu doped ZnS microcrystals were prepared. X-ray diffraction confirms the crystalline and phase of the particles. Morphology and sizes were studied using Scanning Electron Microscopy (SEM). Recorded optical absorption spectra show a band for around 365nm for pure ZnS, but there is a broad band in the near infrared regime for the Cu-doped ZnS microcrystals which are attributed to the d-d transitions of Cu2+ ions. Phonon properties of as-prepared samples were investigated using Raman spectroscopy. Present work we investigate the potential of ZnS and Cu doped ZnS as a photocatalyst. For this from the degradation of methylene blue dye in aqueous media the photocatalytic activity of pure and highest doped ZnS samples with the irradiation of white light and infrared, enhanced photocatalytic activity were observed. Mechanism of white light an IR light based photocatalytic activity is explained based on the electron-hole pair production.

Preparation of the Ag/RGO nanocomposite by use of Abutilon hirtum leaf extract: A recoverable catalyst for the reduction of organic dyes in aqueous medium at room temperature

This paper reports on the biosynthesis, characterization and catalytic activity of silver (Ag) nanoparticles (NPs) supported on the reduced graphene oxide (Ag/RGO) surface using Abutilon hirtum leaf extract as a reducing and capping agent without using any synthetic reagent or toxic chemicals. Introducing A. hirtum leaf extract into an aqueous mixture of AgNO3 and GO caused the speedy reduction of the GO and silver ions and efficiently lead to their nucleation as highly stable Ag NPs on the RGO surface. The crystalline nature of the Ag/RGO nanocomposite was identified using XRD analysis. The possible mechanism leading to the formation of NPs was developed to illustrate this process. The Ag/RGO nanocomposite was employed as catalyst for the reduction of organic dyes such as 4-nitrophenol (4-NP), Congo red (CR) and Rhodamine B (RhB) in the shortest possible time in water at mild conditions. The catalytic reduction reactions were monitored by employing UV-Vis spectroscopy. Furthermore, the nanocomposite can be recovered and recycled several times without significant loss of activity.

Solid‐phase extraction and spectrophotometric determination of Allura Red (E129) in foodstuff, soft drink, syrup and energy drink samples: a comparison study

SummaryAmberlite XAD‐7 and XAD‐8 resins were used as adsorbents for preconcentration and determination of Allura Red (AR) food dye in aqueous medium. The effects of pH, sample volume, sample and eluent flow rates on the extraction of AR were optimised. The determination of dye was performed at 506.0 nm using spectrophotometry. Interference effects of matrix ions and some dyes were also investigated under optimised conditions. The methods permitted low detection limits which were 1.2 and 0.6 μg L−1 for XAD‐7 and XAD‐8, respectively. Adsorption behaviours were investigated by adsorption isotherms and zero charge pH experiments. Validations of the method were performed by determination of AR contents in some foodstuffs. AR contents of liquid samples were found between 58 and 440 μg mL−1. AR concentrations of solid samples were between 416 and 432 μg g−1. The XAD‐7 and XAD‐8 resins presented a fast and reliable potential to determine AR dye in real samples.

Study on the Effect of an Electrolyte on the Self-Aggregation and the Geometry of the Dye Aggregates of Methylene Blue in Aqueous Media

The self-aggregation of Methylene Blue (MB) dye in aqueous media has been investigated spectrophotometrically in presence of sodium chloride (NaCl) at 293.15, 303.15 and 313.15K. The dimerization constant (K<sub>D</sub>) of the MB dye in aqueous solution with or without the electrolyte has been computed using a non-linear least square regression technique. It is observed that presence of the electrolyte resulted into sharp increase in K<sub>D</sub> of MB indicating that presence of the electrolyte favours formation of dye aggregates. There is, however, a decrease in K<sub>D</sub> with increase in temperature. From the observed spectra of the dye, the twist (θ<sub>1</sub>) and the tilt (θ<sub>2</sub>) angles between the dipoles of MB molecules in the aggregates have been computed based on exciton model. Change in the monomeric fractions of the dye (α) in presence of the added electrolyte as a function of the dye concentration has also been computed. The results indicated that the dye aggregates formed is essentially of the sandwich type geometry (H-aggregates) with a slight deviation from an exact parallel stacking arrangement and reduced twist angle. The thermodynamic parameters of the aggregation process in presence of the electrolyte have been evaluated from the temperature dependence of K<sub>D</sub>. It is observed that the aggregation process is an enthalpy rather than entropy controlled one.