Degradation Of Various Dyes Research Articles

Fast photocatalytic degradation of dyes using low-power laser-fabricated Cu2O-Cu nanocomposites.

In this study, we report a simple method to controllably synthesize Cu2O–Cu nanocomposites by using a low-power CO2 laser, and application of these nanomaterials for photocatalytic degradation of methylene blue (MB). Our experiments demonstrate that efficient tailoring of the Cu2O–Cu nanocomposites can be realized by accurate control and optimization of the ambient parameters, such as laser energy and NaOH concentration. Compared to hydrothermally fabricated Cu2O–Cu catalysts, the laser-reduced composites exhibit better visible-light photocatalytic activity for MB degradation, which could be attributed to the formation of special catalytically active structures on the nanocomposite surface. Under the conditions of 10 mA laser irradiation and 5 M NaOH addition, the fabricated Cu2O–Cu composites had the highest catalytic activity. The degradation rate of MB is 90.10% after visible-light irradiation for 50 min under the optimum conditions. The as-synthesized Cu2O–Cu composites showed selective dye degradation, and exhibit relatively higher photocatalytic efficiency for positively charged dyes. This work could lead to facile synthesis of high-performance photocatalysts for fast removal of environmentally hazardous dyes from aqueous solution.

Porous-C3N4 with High Ability for Selective Adsorption and Photodegradation of Dyes Under Visible-Light

Porous-C3N4 with high photocatalytic activity of anionic dyes was successfully synthesized by a SiO2-template method. Its photocatalytic selectivity could easily be switched to cationic dye via a simple post-treatment in NaOH solution. Through careful investigation of influencing parameters (the photocatalytic performances, the structure and surface characteristics of the catalysts), the selective degradation of various dyes is closely related to the adsorption selectivity of the porous g-C3N4 catalysts, which originated from the different surface charge. This study provides a new insight into developing metal-free g-C3N4 photocatalyst with high efficiency and selectivity in environmental purification.

Green Synthesis of Silver Nanoparticle Capped with Allium cepa and Their Catalytic Reduction of Textile Dyes: An Ecofriendly Approach

Today, environment pollution control is a matter of concern, everybody is willing to make a product that should be ecofriendly. Nowadays, water resources are full of untreated waste materials, discharge of hazardous and toxic dyes coming from textile and other chemical industries. These environmental hazards are difficult to remove by commercial water treatment plans, thus we need something that would present an efficient means for removal of these hazards. In this research paper, we have synthesize silver nanoparticle in a green way by using aqueous extract of Allium cepa (onion), and further these silver nanoparticle were tested for the catalytic degradation of various dyes by UV/Visible spectroscopy and silver nanoparticle showed reduction in dyes intensity after a particular period of incubation time. SEM and TEM, Particle size and Zeta potential analysis was done to analyze the surface morphology, particle size range and stability of the silver nanoparticle. Greenly synthesized silver nanoparticle was found to be spherical in shape, having particle size value ranged from 50 to 100 nm with a zeta potential value of −29 mV. An EDX spectroscopy method was used to confirm the presence of silver nanoparticle in the synthesized material. An X-ray crystallography was done to ensure the crystallinity of the silver nanoparticle. Further an ATR-FTIR was performed to confirm the capping of the silver nanoparticle with the phenolic group of the onion. All these study emphasized that silver nanoparticle capped with onion (AgNPs@Ac) is the excellent catalyst for the reduction of hazardous and toxic dyes as well as they serve best purpose of the eco-friendly approach.

Preparation of TiO2/Cobalt Ferrite/Reduced Graphene Oxide Nanocomposite Based Magnetically Separable Catalyst with Improved Photocatalytic Activity

We report a simple synthetic route for the preparation of titanium dioxide (TiO2), cobalt ferrite (CoFe2O4) nanoparticle and reduced graphene oxide (RGO) based nanocomposites TiO2/CoFe2O4/RGO. This is the first time a non-hydrothermal technique is reported for preparation of TiO2/CoFe2O4/RGO nanocomposites. Moreover, unlike other reported methods only water was used as reaction medium. Catalytic activity of synthesized nanocomposites towards degradation of various dyes, such as Methyl Orange, Rhodamine B, Methylene Blue under visible light were investigated. Catalysis reactions were monitored by using UV-vis spectroscopy. TiO2/CoFe2O4/RGO exhibited its high capability to act as an excellent magnetically separable catalyst towards degradation of various dyes under visible light. The high catalytic activity and simple preparation methodology make TiO2/CoFe2O4/RGO nanocomposites an attractive catalyst for degradation of hazardous organic dyes.

A simple combustion method for the synthesis of multi-functional ZrO2/CuO nanocomposites: Excellent performance as Sunlight photocatalysts and enhanced latent fingerprint detection

A facile solution combustion synthesis has been adopted to synthesize ZrO2/CuO nanocomposite oxides (NCO’s) by utilizing Oxalyl dihydrazide (ODH) as fuel. The X-ray diffraction patterns and TEM analysis reveals the presence of cubic ZrO2 and CuO in ZrO2/CuO NCO’s. The NCO’s synthesized by simple, fast, highly sensitive and low-cost method is found to be an alternate to traditional luminescent powders for the detection and enhancement of finger marks in a broad range of surfaces. The photoluminescence analysis indicates that the present NCO is an effective blue component in display applications. The synthesized ZrO2/CuO (2:1) composite exhibited excellent photocatalytic activity towards the degradation of various dyes under Sunlight. In particular, Indigo carmine dye was chosen to explore the photocatalytic performance of prepared NCO’s under Sunlight illumination. It was found that ZrO2:CuO (2:1) NCO showed enhanced photocatalytic activity of 97% which was found to be 3.3 times 2.4 times and 1.5 times higher than that of pure ZrO2, CuO and commercial P25. This can be mainly attributed to the balance between the parameters, band gap, nature of morphology, crystallite size, defects and surface area which causes a slow electron-hole pair recombination rate with fast electron transfer ability. It opens new window to use this simple method to synthesize multifunctional character ZrO2-based composite materials in the area of photocatalysis particularly waste water treatment, display applications as well as a labeling agent to enhance latent fingerprints.

Facile preparation of Zn0.5Cd0.5S@RGO nanocomposites as efficient visible light driven photocatalysts

Abstract The reduced graphene oxide (RGO) loaded Zn 0.5 Cd 0.5 S nanocomposite has been successfully prepared by a facile solvothermal method. The as-prepared photocatalysts were characterized by a combination of X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and N 2 absorption-desorption. The Zn 0.5 Cd 0.5 S@RGO composites with a RGO content of 0.5 wt% (GS-0.5) showed the highest photocatalytic activity for the degradation of various dyes (methylene blue, methyl orange and Rhodamine B), which is mainly due to the uniform dispersion of nanoparticles on RGO sheets and the enhanced separation rate of photo-induced electrons and holes. The GS-0.5 photocatalyst can be repetitively used without significant loss of activity. This new material holds great promise for applications in the field of water purification as well as optoelectronic fields at a large scale.

Ultrafine palladium nanoparticle-bonded to polyetheylenimine grafted reduced graphene oxide nanosheets: Highly active and recyclable catalyst for degradation of dyes and pigments

Much attention has been increasingly focused on the applications of noble metal nanoparticles (NPs) for the catalytic degradation of various dyes and pigments in industrial wastewater. We have demonstrated that Pd NPs/Fe3O4-PEI-RGO nanohybrids exhibit high catalytic activity and excellent durability in reductive degradation of MO, R6G, RB. Specific surface area was successfully prepared by simultaneous reduction of Pd(OAc)2 chelating to PEI grafted graphene oxide nanosheets modified with Fe3O4. The as-prepared Pd NPs/Fe3O4-PEI-RGO nanohybrids were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, high-resolution TEM and energy dispersive X-ray spectroscopy, and UV-lambda 800 spectrophotometer, respectively. The catalytic activity of Pd NPs/Fe3O4-PEI-RGO nanohybrids to the degradation of MO, R6G, RB with NaBH4 was tracked by UV-visible spectroscopy. It was clearly demonstrated that Pd NPs/Fe3O4-PEI-RGO nanohybrids exhibited high catalytic activity toward the degradation of dyes and pigments, which could be relevant to the high surface areas of Pd NPs and synergistic effect on transfer of electrons between reduced graphene oxide (RGO), PEI and Pd NPs. Notably, Pd NPs/Fe3O4-PEI-RGO nanohybrids were easily separated and recycled thirteen times without obvious decrease in system. Convincingly, Pd NPs/Fe3O4-PEI-RGO nanohybrids would be a promising catalyst for treating industrial wastewater.

Room Temperature Synthesis of Copper Oxide Nanoparticles: Morphological Evaluation and Their Catalytic Applications for Degradation of Dyes and C–N Bond Formation Reaction

AbstractSynthesis of copper oxide (Cu2O and CuO) nanoparticles in different morphologies by a facile and cost effective method has been developed at room temperature. The effect of various copper precursors on the morphology of Cu2O nanoparticles has been addressed and achieved the 100 % uniform cubic morphology of Cu2O nanoparticles. The effect of different capping agents and bases also examined and selectively achieved rod, wire, belt like morphologies of CuO nanoparticles. The each capping agent plays the important role and responsible in building the morphology of copper oxide nanoparticles. Notably the synthesis procedure is simple, faster, economical and energy efficient as compared to the other existing methods with selectivity in morphology of copper oxide nanoparticles. In addition, we have shown the catalytic applications of synthesized Cu2O nanoparticles for the degradation of various dyes like methylene blue, methyl red and crystal violet and also as an efficient catalyst for C–N bond formation coupling reaction.

Degradation of methyl orange by heterogeneous Fenton-like oxidation on a nano-organometallic compound in the presence of multi-walled carbon nanotubes

In this study, heterogeneous Fenton-like processes using ferrocene groups immobilized on aluminum-silicate nanoparticles and multi-walled carbon nanotubes (Si/Al@Fe/MWCNT) show a high degradation and decolorization efficiency for methyl orange (MO). The effects of several parameters such as pH, initial H2O2 concentration, reaction time, catalyst loading, and temperature on the oxidative degradation and decolorization of MO have been studied. The seven cycles of the Fenton-like processes utilizing the aforementioned catalyst showed the steady removal of MO, thereby demonstrating the high stability of the Si/Al@Fe/MWCNT system over several Fenton oxidation processes. Scavenging of the HO produced in the reaction media was assessed using n-butanol and KI and confirmed that this radical, which is generated upon decomposition of H2O2, is mainly responsible for the heterogeneous Fenton-like oxidation of MO. A feasible Fenton-like oxidation pathway for MO in the presence of the Si/Al@Fe/MWCNT nanocatalyst was proposed. Finally, the degradation of various dyes using the Si/Al@Fe/MWCNT system was compared.

Photocatalytic decolorization of methylene blue using zinc oxide supported on mesoporous silica nanoparticles

Various dyes that are used in textile, paper, cosmetics and plastics industries may produce harmful effects on the health of living organisms and the environment if not treated properly before being discharged into water bodies. Among many techniques, photocatalytic process is one of the promising treatment for these dyes. Zinc oxide (ZnO) is well-known comparable with TiO2 due to its unique properties and numerous advantages. While, mesoporous silica nanoparticles (MSN) is an excellent solid support for heterogeneous catalysts due to its high surface area, thermal and mechanical stability, highly uniform pore distribution, tunable pore size, and unique hosting properties. Therefore, in this study, ZnO/MSN (ZM) catalysts were prepared and its physicochemical properties was characterized by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The catalyst was tested on the photodecolorization of methylene blue (MB) dye. The results showed that the interaction between ZnO and MSN support could enhanced the photocatalytic activity. The 0.5 g L-1 of 5ZM was found to give the highest degradation (80 %) of 10 mg L-1 of MB solution at pH 7 after 3 h under UV light irradiation. The photodecolorization followed the pseudo first-order Langmuir-Hinshelwood kinetic model. This study demonstrated that the prepared 5ZM has a potential to be used in photocatalytic degradation of various dyes as well as organic pollutants.

Photo-Fenton degradation of rhodamine B using Fe2O3–Kaolin as heterogeneous catalyst: Characterization, process optimization and mechanism

An efficient Fe2O3–Kaolin was synthesized as a heterogeneous catalyst for photo-Fenton degradation of organic contaminants. X-ray photoelectron spectroscopy analysis and high-resolution transmission electron microscope analysis confirmed the existence of Fe2O3 nanoparticles in the Fe2O3–Kaolin composite. The specific surface area of the Fe2O3–Kaolin catalyst increased from 19.47 to 39.32m2/g compared to kaolin. The catalytic activity of the Fe2O3–Kaolin catalyst was evaluated by the photo-Fenton degradation of rhodamine B (RhB) under visible light irradiation and the results showed that the catalyst was highly effective for the degradation of RhB in a wide pH range of 2.21–10.13. At optimal conditions, 98% discoloration and 66% mineralization of RhB were achieved in 120min. The catalyst was efficient for the degradation of methylene blue as well. Leaching test indicated that the leached iron from the catalyst was negligible and the catalyst still showed high photocatalytic activity after five reaction cycles, which all showed that the Fe2O3–Kaolin catalyst is a promising heterogeneous photocatalyst for the degradation of various dyes in wastewater. Finally, a possible photocatalytic mechanism was proposed based on photoluminescence measurements and a series of operating conditions.

Ternary Titania–Cobalt Ferrite–Polyaniline Nanocomposite: A Magnetically Recyclable Hybrid for Adsorption and Photodegradation of Dyes under Visible Light

A straightforward strategy is designed for the fabrication of magnetically recyclable ternary titania–cobalt ferrite–polyaniline (P25-CoFe2O4-PANI) photocatalysts with differing P25/CoFe2O4 ratio. The pseudo-second-order and Langmuir models are found to be most suitable for describing the adsorption of methyl orange (MO) onto the photocatalysts. The photocatalytic activity of P25-CoFe2O4-PANI is evaluated by the degradation of various dyes under visible light irradiation, and the results show that the ternary P25-CoFe2O4-PANI photocatalyst exhibits high photocatalytic activity due to the good adsorption capacity of the hybrid and the introduction of P25, which can further improve the separation of the light-induced electron–hole pairs. The degradation of anionic dyes is much more effective than that of cationic dyes due to the negatively charged groups of anionic dyes undergo electrostatic attraction with the positively charged backbone of PANI, and such an effective adsorption helps in promoting the degr...

Photodecolorization of methyl orange over α-Fe2O3-supported HY catalysts: The effects of catalyst preparation and dealumination

An α-Fe2O3-supported HY zeolite (α-Fe2O3/HY) was prepared by introducing nanosized α-Fe2O3 into an HY zeolite support through in situ (α-Fe2O3/HYIS) and ion-exchange (α-Fe2O3/HYIE) methods. The effect of the preparation methods on the physicochemical properties of the catalyst were studied via XRD, FESEM-EDX, TEM, UV–vis DRS, FTIR, XPS, 29Si and 27Al MAS NMR, ESR and BET surface area analysis. In this study, dealumination was accomplished by using a facile electrolysis system without any strong acids, reactive compounds and/or hydrothermal treatment. Dealumination accompanied by ion exchange of Al with Fe3+ ions in the HY zeolite framework resulted in the formation of an active species that had a higher photoactivity towards the decolorization of methyl orange (MO). A 5wt% α-Fe2O3/HYIS was found to produce an 80% photodecolorization of 30mgL−1 of MO at pH 2 with 0.375gL−1 catalyst, while 5wt% α-Fe2O3/HYIE only produced 23% photodecolorization under similar conditions (2h reaction time). This study showed that the kinetics follow a pseudo-first order Langmuir–Hinshelwood model with an activation energy (Ea) calculated for both 5wt% α-Fe2O3/HYIS and 5wt% α-Fe2O3/HYIE to be 45.8kJmol−1 and 70.2kJmol−1, respectively. Measurements of the mineralization of MO by COD, BOD5 and TOC analysis were 27.0%, 69.6% and 16.9%, respectively, after 2h of contact time. The Fe dissolution from the catalyst showed insignificant leaching of Fe (<1%) when subjected to AAS. A reusability study demonstrated that α-Fe2O3/HYIS could be a promising photocatalyst for the degradation of various dyes in wastewater.

Photocatalytic Degradation of Various Dyes by Strontium Titanate Nanoparticles

A simple polyacrylamide gel method was used to prepare strontium titanate (SrTiO3) nanoparticles. X-ray diffraction (XRD) analysis reveals that single-phase SrTiO3 can be synthesized at a calcination temperature of 550 °C. Scanning electron microscope (SEM) observation shows that the as-prepared SrTiO3 particles are regularly shaped like spheres and highly uniform in size with an average diameter of ~55 nm. Ultraviolet (UV)-visible diffuse reflectance spectrum analysis indicates that the bandgap of the sample is 3.23 eV. The Brunauer-Emmett-Teller (BET) specific surface area of the sample is measured, by the N2 adsorption-desorption technique, to be 26.4 m2•g−1. The photocatalytic experiments reveal that the SrTiO3 nanoparticles can effectively degrade various dyes including congo red (CR), rhodamine B (RhB), methyl orange (MO), and methylene blue (MB) under UV irradiation.

Synthesis, Structure, Negative Thermal Expansion, and Photocatalytic Property of Mo Doped ZrV2O7

A new series of compounds identified in the phase diagram of ZrO(2)-V(2)O(5)-MoO(3) have been synthesized via the solution combustion method. Single crystals of one of the compounds in the series, ZrV(1.50)Mo(0.50)O(7.25), were grown by the melt-cool technique from the starting materials with double the MoO(3) quantity. The room temperature average crystal structure of the grown crystals was solved using the single crystal X-ray diffraction technique. The crystals belong to the cubic crystal system, space group Pa3 (No. 205) with a = 8.8969 (4) Å, V = 704.24 (6) Å(3), and Z = 4. The final R(1) value of 0.0213 was achieved for 288 independent reflections during the structure refinement. The Zr(4+) occupies the special position (4a) whereas V(5+) and Mo(6+) occupy two unique (8c) Wyckoff positions. Two fully occupied O atoms, (24d) and (4b), one partially occupied O atom (8c) have been identified for this molybdovanadate, which is a unique feature for these crystals. The structure is related to both ZrV(2)O(7) and cubic ZrMo(2)O(8). The temperature dependent single crystal studies show negative thermal expansion above 370 K. The compounds have been characterized by powder X-ray diffraction, solid-state UV-vis diffuse reflectance spectra, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The photocatalytic activity of these compounds has been investigated for the degradation of various dyes, and these compounds show specificity toward the degradation of non-azoic dyes.

A novel method treating organic wastewater: Air-bubble cavitation passing small glass balls

Here, a novel degradation method, air-bubble cavitation induced by air-bubble passing small glass balls, was provided to effectively degrade organic pollutants in wastewaters. In order to demonstrate its universality, the degradation of various dyes (Methyl Orange (MO), Rhodamine B (RM-B), Congo Red (CG-R), Azo Fuchsin (AF) and Acid Red B (AR-B)) was carried out. Meanwhile, the effect of operating parameters such as air-bubbling time, dye initial concentration, NaCl addition amount and glass-ball size on the degradation were investigated. The results showed that the degradation ratio of Methyl Orange in aqueous solution reached 37.82% when the experimental conditions of 10 mg/L initial concentration, 3.0–3.5 mm glass-ball size, 4.5 L/min gas flow rate and pH = 6.0 were adopted with 3.0 h air-bubbling at room temperature (25.0 ± 0.2 °C). Under the same condition, the degradation ratios attained to 60.37%, 64.52%, 71.75% and 75.64%, respectively, for Rhodamine B, Congo Red, Azo Fuchsin and Acid Red B. In addition, the process of air-bubble cavitation and possible degradation mechanism of organic pollutants were discussed primarily. All experiments indicate that this method is an effective, energy saving and simple reaction device for the treatment of organic wastewaters. Hence the degradation by means of air-bubble cavitation is expected to be feasible and promising as an advisable choice for the treatment of organic wastewaters in future.

Investigation on solar photocatalytic degradation of various dyes in the presence of Er 3+:YAlO 3/ZnO–TiO 2 composite

In this work, Er 3+:YAlO 3/ZnO–TiO 2 and ZnO–TiO 2 composites were prepared by the ultrasonic dispersion and liquid boiling method. In succession, they were then characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Acid red B as a model dye compound was degraded under solar light irradiation to evaluate the photocatalytic activities of the Er 3+:YAlO 3/ZnO–TiO 2 and ZnO–TiO 2 composites. We found that the photocatalytic activity of ZnO–TiO 2 composite can be enhanced by adding an appropriate amount of Er 3+:YAlO 3. We reviewed influencing factors, such as Er 3+:YAlO 3 content, heat-treated temperature and heat-treated time on the photocatalytic activity of the Er 3+:YAlO 3/ZnO–TiO 2 composites. In addition, the effects of solar light irradiation time, dye initial concentration, Er 3+:YAlO 3/ZnO–TiO 2 amount and solution acidity on the photocatalytic degradation of acid red B dye in aqueous solution were investigated in detail. Simultaneously, the degradation and comparison of other dyes such as methyl orange (MO), rhodamine B (RM-B), azo fuchsine (AF), congo red (CG-R) and methyl blue (MB) were also reviewed. In addition, we attempted to explore both the principle of possible excitation of Er 3+:YAlO 3/ZnO–TiO 2 under solar light irradiation and the mechanism of photocatalytic degradation.

Synthesis, Structure, and Photocatalytic Activity in Orthorhombic Perovskites LnVO3 and Ln1−xTixVO3 (Ln = Ce, Pr, and Nd)

Orthorhombic perovskite type LnVO3 and Ln1−xTixVO3 (Ln = Ce, Pr, and Nd) have been synthesized by the solid state method. The structures of these compounds have been unequivocally established based on high resolution powder X-ray diffraction data using Rietveld refinement methodology followed by difference Fourier analysis. It is shown that substitution of Ti occurs at the vanadium site and not at the cerium site. The compounds have been tested for photocatalytic degradation of various dyes and substituted phenols. It is observed that doping of Ti remarkably improves the photodegradation efficiency of these orthorhombic perovskites.

Synthesis, structure and photocatalytic properties of β-ZrMo2O8

Monoclinic ZrMo2O8 was synthesized via solid state method and single crystals of the title compound have been grown by the hydrothermal method. The crystals belong to monoclinic crystal system with space group C2/c (No. 15) with a = 11·4243(19) Å, b = 7·9297(6) Å, c = 7·4610(14) Å and β = 122·15(2)°, Z = 4. The bandgap of the compound was 2·57 eV. Unlike the other polymorphs of ZrMo2O8, the monoclinic form has unique crystallographic features with ZrO8 and Mo2O8 polyhedra. The photocatalytic activity of this compound has been investigated for the first time for the degradation of various dyes under UV irradiation and has been compared with the photoactivity of the trigonal form of ZrMo2O8. It has been observed that this compound exhibits specificity towards the degradation of cationic dyes.

Synthesis, Characterization, and Photocatalytic Properties of ZrMo2O8

ZrMo2O8 was synthesized via two routes, namely, the traditional solid-state method and the solution combustion method. The compounds were characterized by powder X-ray diffraction, UV−visible spectroscopy, scanning electron microscopy, and transmission electron microscopy. The crystals belong to a trigonal crystal system, space group P 1c (No. 163) with a = 10.1391(6) A, c = 11.7084(8) A, and Z = 6. The band gap of the compounds was around 2.7 eV, and DFT calculations suggest the indirect nature of the band gap. The irregular MoO4 tetrahedra create a dipole and inhibit the process of electron−hole recombination, thereby making the material photoactive. The photocatalytic activity of the compounds prepared by both routes has been investigated for the degradation of various dyes under UV irradiation, and this showed the specificity of the compounds towards the degradation of non-anthraquinonic dyes.