Photodegradation Of Azo Dye Research Articles

Synthesized rGO/f-MWCNT-architectured 1-D ZnO nanocomposites for azo dyes adsorption, photocatalytic degradation, and biological applications

A study has synthesized a composite of carbonaceous nanomaterials, including functionalized multi-walled carbon nanotubes (f-MWCNT) and reduced graphene oxide (rGO), with 1D-architectured zinc oxide nanorods (ZnO NRs), for applications in adsorption and sunlight-assisted photocatalytic degradation. We modified the composite with 1% w/w rGO and f-MWCNT. We studied the adsorption and photodegradation of azo dyes using ZnO and its nanocomposites. The photocatalysts of RZnO and CZnO nanocomposite degraded RhB, MB, CV, MO, and CR dyes with a degradation percentage of 92 to 97%. The nanocomposite demonstrated superior antimicrobial and antioxidant properties compared to ZnO NRs, highlighting their potential in drug delivery.

Chemoinformatics Analysis of the Colour Fastness Properties of Acid and Direct Dyes in Textile Coloration

The efficiency of chemoinformatics methods based on a fragment approach for the analysis of relationships between the chemical structure of textile dyes and colour fastness of the dyeings have been shown by examining a large set of properties, including the light fastness of acid dyes on wool and polyamide fibres, the sensitivity of acid dyes on wool to oxygen bleaching, the wash fastness of acid dyes on wool, the adsorption of direct dyes on cotton, and the photodegradation of azo dyes in solution. An analysis of the developed regression models depicted the contribution of ten substructural molecular fragments for each indicator of the colour fastness properties of acid and direct azo dyes on textile materials. The similarity of several individual multi-atomic fragments for acid and direct azo dyes was found for wool, polyamide, and cotton fibres, which indicates the coinciding mechanisms of the physicochemical processes that accompany the destruction of dyes while testing the light fastness and sensitivity of the dyeings to oxygen bleaching, as well as their adsorption/desorption with the wash fastness and dyeability of wool and cotton.

Photodegradation of Azo Dyes in Sunlight Promoted by Nitrogen–Sulfur–Phosphorus Codoped Carbon Dots

Photodegradation of Azo Dyes in Sunlight Promoted by Nitrogen–Sulfur–Phosphorus Codoped Carbon Dots

Spinel oxide ZnCr2O4 incorporated with ZnS quantum dots for application on visible light driven photocatalyst Azo dye degradation

Azo dyes, a kind of synthetic dye stuff, have a wide range of applications in textile, leather, food and printing industries, but it causes adverse health effects to human beings and to the ecosystem. Herein, we report the photocatalytic degradation of methyl orange dye, by using ZnS/ZnCr2O4 nanohybrid sample. The samples were prepared by simple precipitation process and characterized in order to investigate its crystallinity, morphology, functional group, photophysical properties, elemental composition and mapping. The amino acid capped ZnS/ZnCr2O4 nanohybrid show enhanced photocatalytic properties in the photodegradation of azo dye, compared to that of bare ZnS QDs and ZnCr2O4 nanoparticles. The nanohybrid remain unaffected after four cycles of azo dye degradation. The enhanced performance might be due to the formation of interface between ZnS QDs and ZnCr2O4 nanoparticles. The methionine capped ZnS/ZnCr2O4 nanohybrid provide a new hope to develop an efficient and commercializable photocatalyst with improved efficiency.

Quantitative structure-activity relationship in the photodegradation of azo dyes

The photolysis characteristics of azo dyes are critically important in environmental pollution control, dye-sensitized solar cells, and dyeing-related industries. However, there is still lack of quantitative relationship between the structures of azo dyes and their photolysis characteristics. To address this issue, the photolysis of 22 azo dyes were conducted side by side at three pH (4.0, 6.0, 9.0). The obtained pseudo-first order photodegradation rate constants (k1) were processed with meta-analysis. Statistically, the hydrazone tautomer had a smaller excitation energy and was easier to undergo photolysis than the azo tautomer. The ortho-substituted sulfonate groups had an obvious protective effect on the photostability of azo dyes. The softness (s), the most positive and negative partial charge on a carbon atom (qC+, qC−) were found to be crucial descriptors in the establishment of QSAR models for the photostability of azo dyes. The QSAR model at pH 9.0 was robust for predicting the photostability of azo dyes under UV irradiation. N2-purging experiments and quantum chemical computation verified that the cleavage of azo bond was not a result of direct photolysis but was caused by the attack of photoinduced reactive oxygen species. The results here are helpful for the design of more stable azo dyes or the selection of suitable approaches for the treatment of dye-contaminated water bodies.

Investigation of electron beam irradiation on In2S3-MxInySz (M = Bi or La) Z-scheme heterojunctions for efficient and stable degradation of water pollutants

Novel Z-scheme In2S3-MxInySz (M = Bi or La) heterojunction composites were fabricated through a hydrothermal method. An electron beam irradiation technology has been served for artificially creating interface defects on the composites to further enhance photocatalytic activity. SEM and TEM results showed that In2S3-MxInySz composites presented tubular structures composed of randomly assembled ultrathin nanosheets with the incorporation of Bi and La. XRD, FT-IR and XPS results proved that the as-synthesized heterostructure composites were mainly InBiS3 and InLa3S6. The In2S3-MxInySz composites presented distinct optical absorption property in visible lights region and exhibited highly enhanced photocatalytic efficiency for the removal of azo dyes and Cr(VI). Specifically, ISB-60 irradiated by electron beam displayed the best removal efficiency for the water pollutants. PL, DRS and EIS measurements showed that electron beam irradiation could reduce the recombination rate of photoexcited electron-hole pair, resulting in great separation rate of charge carriers. The ESR results confirmed the existence of superoxide radical (•O2−), hole (h+) and hydroxyl radical (•OH) in the photocatalysis process. The •O2− and h+ species possessed a significant oxidizing effect towards the photodegradation of azo dyes and the photoreduction of Cr(VI). The possible transformation pathway for the removal of water pollutants by In2S3-MxInySz (M = Bi or La) composites was proposed by means of GC-MS.

Evaluation of effect from Ag-AgX (X = Cl, Br, I) on photodegradation of azo dyes

AgX (X = Cl, Br, I) is prepared by the precipitation method. AgX can easily become Ag-AgX by the indoor sunlight due to its photosensitivity, especially in the case of AgCl and AgBr. In order to evaluate the effect from Ag-AgX, under the simulated sunlight illumination, photodegradation reactions of azo dyes (methyl orange and congo red) by Ag-AgX are performed. The photodegradation kinetics of azo dyes by Ag-AgCl or Ag-AgBr is rapid; however, the photodegradation kinetics of azo dyes by Ag-AgI is slow. We measure HO· generated from Ag-AgX systems and characterize Ag-AgX using different techniques. In this work, though, our focus is to elucidate that Ag-AgX can be decomposed irreversibly by the indoor sunlight, as well as by the simulated sunlight illumination. Therefore, we should not term Ag-AgX the photocatalyst, and we should not term the effect from Ag-AgX the photocatalysis.

Photodegradation of azo dyes: photocatalyst and magnetic investigation of CoFe2O4–TiO2–Ag nanocomposites

In the first step, CoFe2O4 nanostructures were synthesized via a facile precipitation method without using any surfactant. The CoFe2O4-TiO2 nanocomposites were then prepared using the sol–gel method. The silver nanoparticles were produced by reducing silver nitrate (AgNO3) with sodium borohydride (NaBH4). By adding a reducing agent, CoFe2O4–TiO2–Ag was produced by a simple precipitation method. The prepared products were characterized by X-ray diffraction and scanning electron microscopy. The vibrating sample magnetometer shows the ferromagnetic property of ferrite nanostructures. The photocatalytic behavior of the CoFe2O4–TiO2–Ag nanocomposites was evaluated using the degradation of three dyes (acid violet, methyl orange, and acid blue) method ultraviolet light irradiation. The results showed a nanocomposite with an applicable magnetic and photocatalytic performance.

SDS capped and PVA capped ZnO nanostructures with high photocatalytic performance toward photodegradation of reactive red (RR141) azo dye

Two types of ZnO nanostructures have been synthesized successfully in high yield by using either sodium dodecylsulfate (SDS) or polyvinyl alcohol (PVA) as a capping agent via a facile and low temperture chemical precipitation method. The synthesized ZnO samples show well crystallized wurtzite hexagonal phase. The SDS surfactant played a crucial effect on morphology, specific surface area and photocatalytic performance of the ZnO photocatalyst. SDS capped ZnO with high specific surface area of 14.8m2g−1 shows much higher photocatalytic performance in comparision to that of PVA capped ZnO. Nearly 95% and 88% of reactive red (RR141) azo dye decomposed after irradiation for 240min under UV light and 80min under solar light, respectively. The photodegradation reaction follows the pseudo first-order kinetics with the high rate constant (k) of 0.04min−1. The SDS capped ZnO photocatalyst retains its original efficiency of about 87% even after the third cycles of reuse indicating the advantages of stability and reusability. Hole and hydroxyl radical are the two major reactive species involving in photodegradation of azo dye. ZnO nanostructures with SDS as a capping agent will be suitable for photodegradation of organic pollutants in the environmental protection. The method and ideas presented herein will potentially provide cheaper and cleaner means for treatment of a large volume of organic dyes. The photodegradation process can be performed very easily even under solar light irradiation. This offers some insight into the progress of technological applications related to the degradation of industrial dyes.

Photo-degradation of azo dyes: photo catalyst and magnetic investigation of CuFe2O4–TiO2 nanoparticles and nanocomposites

CuFe2O4 nanoparticles were first synthesized via a fast and simple precipitation method. Then CuFe2O4–TiO2 nanocomposites were prepared using sol–gel method. The prepared products were characterized by X-ray diffraction, scanning electron microscopy, and fourier transform infrared spectroscopy. Alternating gradient force magnetometer was used to study the magnetic property of the products. The results illustrated either superparamagnetic or ferromagnetic behaviour of CuFe2O4 nanoparticles. The photo-catalytic behaviour of CuFe2O4–TiO2 nanocomposites was evaluated using the degradation of four various azo dyes under ultraviolet light irradiation. The results show that the prepared nanocomposites are applicable for magnetic and photo-catalytic performance.

Pechini synthesis of Co2SiO4 magnetic nanoparticles and its application in photo-degradation of azo dyes

In this work Co2SiO4 nanoparticles were synthesized via a facile Pechini sol-gel method. The prepared products were characterized by X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FT-IR) spectroscopy. Alternating gradient force magnetometer (AGFM) illustrates para-magnetic behaviour of Co2SiO4 nanoparticles. The photocatalytic behaviour of Co2SiO4 nanoparticles was evaluated using the degradation of three azo dyes (acid black, acid brown and methyl orange) under ultraviolet light irradiation. The results show that nanocomposites have applicable magnetic and photocatalytic performance. In order to prepare polymeric nanocomposite, Co2SiO4 were added to poly styrene (PS) and polysulfone (PSu) matrices. Outcomes confirm that nanoparticles appropriately enhanced both thermal stability and flame retardant property of the PSu and PS matrices.

Photo-degradation of azo-dyes by applicable magnetic zeolite Y–Silver–CoFe2O4 nanocomposites

Magnetic CoFe2O4 and silver nanoparticles were synthesized via simple chemical reactions using precipitation method at temperature of 60 °C. The all obtained materials are in the range of nano-scale magnetic particles. The effect of different surfactants (anionic, cationic and neutral) on the morphology of the products was investigated. zeolite Y–Ag–CoFe2O4 nanocomposites were also prepared by so called “ship in bottle” procedure. Scanning electron microscopy, X-ray diffraction pattern, Fourier transform infra-red were used to study the structural and physical properties of CoFe2O4 nanoparticles. The magnetic properties of the product were also investigated using a vibrating sample magnetometer. The cobalt ferrite nanoparticles exhibit various ferromagnetic behaviours by changing in surfactants at room temperature. The photocatalytic behaviour of zeolite Y–Ag–CoFe2O4 nanocomposite was evaluated using the degradation of four various azo dyes aqueous solution under UV light irradiation. The results confirm that zeolite Y–Ag–CoFe2O4 nanocomposites are suitable materials with suitable performance in photo-catalytic applications.

Deciphering effects of functional groups and electron density on azo dyes degradation by graphene loaded TiO2

This study tended to decipher the mechanism of photo degradation of azo dyes, which bond was favorable to be broken for application of wastewater decolorization. That is, from chemical structure perspective, the critical substituents to affect electron donor/acceptor for dye degradation would be identified in this research. The model reactive blacks (RB5), reactive blue 171 (RB171) and reactive red 198 (RR198) were degraded by graphene loaded TiO2, indicating how the electron withdrawing and releasing groups affect azo dye degradability. The byproducts and intermediate products were analyzed by ultraviolet–visible spectroscopy (UV–vis), gas chromatography–mass spectrometry (GC–MS) and ion chromatography (IC). Furthermore, the radicals involved in the reaction were found by electron paramagnetic resonance (ESR) to confirm the main oxidized species of hydroxyl radicals rather than the light generated positive holes. The finding revealed that the breakages of the bonds were due to the electron density changes around the bonds. This principle can be applicable not only for RB5 degradation, but also for reactive blue 171 (RB171), reactive red 198 (RR198) and some other textile dyes.

New controllable procedure for preparation of SrSnO3 nanostructures: photo-degradation of azo dyes and photovoltaic measurement

SrSnO3 nanoparticles were prepared by a facile co-precipitation method in solvent of water. In this method, complex of strontium was applied as a new precursor to achieve SrSnO3 nanoparticles. Different parameters on morphology of product such as precipitation agent (alkaline), temperature, the rate of stirrer and surfactant were optimized to achieve the best quality product. Two types of azo dyes (acid blue 92 and acid black 1) at presence of ultraviolet and visible light appropriately were degraded from aqueous solution. Results show that the powder illustrate suitable catalytic behavior for degradation of dyes (93 % for monoazo and 96 % for diazo). SrSnO3 nanoparticle was also applied in photovoltaic measurement. As-prepared nanomaterials show photovoltaic behavior in presence of metal free dye.

Facile synthesis of a Ag(i)-doped coordination polymer with enhanced catalytic performance in the photodegradation of azo dyes in water

Immersing {[Pb(Tab)2(bpe)]2(PF6)4}n into AgNO3 solution produced a Ag(i)-doped coordination polymer {[Pb(Tab)2(bpe)]2(PF6)4·1.64AgNO3}n, which enhanced the catalytic activity towards azo dye photodegradation.

Preyssler Heteropolyacid: A Green and Eco-friendly Catalyst in the Hydrothermal Synthesis of ZnO Nanostructures and their Applications in Photodegradation of Azo Dyes

Preyssler Heteropolyacid: A Green and Eco-friendly Catalyst in the Hydrothermal Synthesis of ZnO Nanostructures and their Applications in Photodegradation of Azo Dyes

Different combinations of Fe3O4 microsphere, Polypyrrole and silver as core–shell nanocomposites for adsorption and photocatalytic application

Several core–shell nanocomposites composed of Fe3O4 microspheres, Polypyrrole and silver were fabricated here by a series of wet chemical methods. The as-prepared nanocomposites were further used in adsorption and photodegradation of azo dyes. The chemical properties of the products were characterized by a series of techniques and equipment. The adsorption and photocatalytic activities of the obtained core–shell heterostructure were studied by controlled experiments. It was found that Fe3O4@PPy nanostructure exhibited the highest removal abilities towards organic dyes in aqueous solution among the as-prepared samples. The final removal ratio is 86.2% and 80.4% for Methyl Orange and Orange II aqueous solutions, respectively. Deposition of Ag nanoparticles was employed here to investigate the transportation and separation of photo-induced charges on the surface or interface of Fe3O4@PPy under UV illumination.

Preparation of polyaniline/TiO2 composite nanotubes for photodegradation of AZO dyes

Polyaniline (PANI) composite nanotubes (90–130 nm in diameter) containing titanium dioxide (TiO2) nanoparticles (about 10 nm in diameter) were synthesized through a self-assembly process in the presence of â-naphthalenesulfonic acid (â-NSA) as the dopant. It was found that PANI-TiO2 composites and PANI nanotubes both behaved with significant photocatalytic activities towards AZO dyes, during 2 h photocatalytic processes under natural light, the degradation ratio was 94.2% and 97.2% respectively (methyl orange and orange II). The morphology of such products was characterized by SEM. The specific surface area of such composite nanotubes was 14.7 m2/g compared to normal polyaniline which was 0.27 m2/g. IR and X-ray diffraction characterizations showed that the chemical chain of the composite nanotubes was identical to that of the doped PANI. It may provide a new way for photodegradation of organic contaminants by using conjugated polymer with dimensional structure.

Study of Homologous Elements: Fe, Co, and Ni Dopant Effects on the Photoreactivity of TiO2 Nanosheets

AbstractDespite sustained effort over the years, additional investigations into the relationship between doping elements and the photocatalytic properties of TiO2 are needed. In this work, Fe‐group(Fe, Co, Ni)‐doped anatase TiO2 nanosheets with exposed {0 0 1} facets are prepared by using a facile solvothermal synthetic route. A change in the type and concentration of the doping element consequently leads to a change in the size and percentage of {0 0 1} facets in the TiO2 nanosheets, and finally causes a significant difference in the photocatalytic activities of the as‐prepared TiO2 samples. In this case, the performance of doped TiO2, which serves as the photocatalyst, is investigated by directly assessing its effect on the photodegradation of azo dyes (methylene blue) under UV and visible light irradiation, respectively. Importantly, for the first time these studies reveal that the order of the activities of the doped TiO2 is Ni>Co>Fe, and the optimal value of the percentage of the doping ions to Ti ions is 0.75 %. Electrochemical impedance spectra, photocurrent, and photoluminescence measurements indicate that the charge separation and transportation rate is mainly influenced by the type and concentration of doping ions, which determines the photodegradation activities of the TiO2 host.

Carbon-Doped Titanium Dioxide Nanoparticles Mediated Photocatalytic Degradation of Azo Dyes Under Visible Light

Visible-light active carbon-doped titanium dioxide (C-TiO2) powders were prepared through sol–gel method and were characterized using powder X-ray diffraction and UV–vis diffuse reflectance spectroscopy techniques. Photocatalytic activity of the prepared catalyst toward the photodegradation of azo dyes, Reactive Red 180 and Reactive Red 141, in the presence of visible light was evaluated. C-TiO2 exhibited enhanced degradation of the dyes compared to Degussa P25 TiO2 nanoparticles. The potential of sulfate radical-producing oxidants (oxone (potassium peroxomonosulfate, PMS), potassium peroxodisulfate) in improving photodegradation of model pollutants has been studied in detail. More than 95 % decolorization of model pollutants was achieved within 20 min in the presence of PMS and the prepared catalyst. The effectiveness of the process has been evaluated by measuring the degree of mineralization of the total organic carbon, a complementary indicator of the treatment efficiencies.