Organic Dyes In Aqueous Medium Research Articles

2D and 3D Ag(I) coordination polymers with a 2-methylimidazole substituted cyclotriphosphazene ligand: Structures and dye adsorption properties

Coordination polymers are a promising crystalline framework for dye capture and separation in recent years. We are reporting herein the two new, Ag(I) coordination polymers, namely {[Ag3(MeIm-Cp)2](NO3)3}n (1) and {[Ag(MeIm-Cp)](CH3PhSO3)} (2), were synthesized from hexapodal-shaped 2-methylimidazole substituted cyclotriphosphazene, (MeIm-Cp). MeIm-Cp was characterised by 1H NMR, 31P NMR and mass analysis. Structure of each isolated compounds were assigned by single crystal X-ray crystallography. In complex 1, MeIm-Cp has a κ6N coordination mode by connecting six Ag(I) ions to constitute a 3D coordination framework whereas the ligand in complex 2 displays κ4N coordination mode via linking four Ag(I) ions together to create a 2D coordination polymer. Topologically, coordination polymer 1 exhibits a 4,4,6-connected three nodal net with point symbol {44.62}3{46.68.8}2, while coordination polymer 2 displays a four-connected network having the point symbol {43.63}. According to thermogravimetric analysis, the thermal stability of MeIm-Cp is higher than complexes. The synthesized coordination polymers were used for the adsorption of some cationic and anionic organic dyes in aqueous media, Dye adsorption studies were performed out using UV–Vis. absorption spectroscopy. Adsorption experiments show that complex 1 removes the anionic methyl orange (MO) and tartrazine (E102) from water but shows no adsorption behaviour toward the cationic methylene blue (MB).

Revealing the Dependency of Dye Adsorption and Photocatalytic Activity of ZnO Nanoparticles on Their Morphology and Defect States.

ZnO is an effective photocatalyst applied to the degradation of organic dyes in aqueous media. In this study, the UV-light and sunlight-driven photocatalytic activities of ZnO nanoparticles are evaluated. A handheld Lovibond photometer was purposefully calibrated in order to monitor the dye removal in outdoor conditions. The effect of ZnO defect states, i.e., the presence of zinc and oxygen defects on the photocatalytic activity was probed for two types of dyes: fuchsin and methylene blue. Three morphologies of ZnO nanoparticles were deliberately selected, i.e., spherical, facetted and a mix of spherical and facetted, ascertained via transmission electron microscopy. Aqueous and non-aqueous sol-gel routes were applied to their synthesis in order to tailor their size, morphology and defect states. Raman spectroscopy demonstrated that the spherical nanoparticles contained a high amount of oxygen vacancies and zinc interstitials. Photoluminescence spectroscopy revealed that the facetted nanoparticles harbored zinc vacancies in addition to oxygen vacancies. A mechanism for dye degradation based on the possible surface defects in facetted nanoparticles is proposed in this work. The reusability of these nanoparticles for five cycles of dye degradation was also analyzed. More specifically, facetted ZnO nanoparticles tend to exhibit higher efficiencies and reusability than spherical nanoparticles.

Reduction of toxic organic dyes in aqueous media using N-heterocyclic copper(II) complex immobilized on the beta-cyclodextrin-modified Fe3O4 nanoparticles as a magnetically recyclable catalyst

This study was undertaken to design a stable easy-recoverable nanoadsorbent (Fe3O4@CM-β-CDP@Tet-Cu(II)) hybrid with rich catalytic sites via wet-chemical method for the catalytic reduction of toxic dyes in wastewater. β-cyclodextrin (β-CD) with a hydrophilic character outside and hydrophobic inside cavity play an important role in catalytic reduction process by interacting with organic molecules and also prepared more sites for further surface modifications. Several characterization techniques including FT-IR, TGA analysis, FE-SEM/EDX, TEM, X-Ray diffraction patterns (XRD) measurements were employed to investigate the structural properties of the synthesized material. The catalytic ability of the obtained material was examined in the presence of different dyes including p-nitrophenol, Eosin Y, Rhodamine B, Congo red, and Methyl orange by UV–Vis spectroscopy as a simple and available method. Moreover, the parameters which effect on reduction process, such as dye and reducing agent (NaBH4) concentrations, mass of adsorbent and time were optimized at room temperature. The obtained data demonstrate the considerable catalytic ability of Fe3O4@CM-β-CDP@Tet-Cu (II) besides a remarkable reduction rate and high yield over a short reaction time, in particular for Methyl orange dye. Recycling experiments revealed that Fe3O4@CM-β-CDP@Tet-Cu (II) has an excellent stability wherein the catalyst was recycled five times with a slight decrease in the reduction ability without any remarkable change in morphological properties which confirm by FE-SEM analysis. The high catalytic activity, the magnetic recoverability, along with the excellent stability of Fe3O4@CM-β-CDP@Tet-Cu (II) make it a potential candidate for the reduction of multiple dyes in real wastewater samples.

Novel anthracene and pyrene containing Cd(II)-based coordination polymers for adsorptive removal of toxic dyes from aqueous medium

In the present work, we have synthesized two new one- and two-dimensional Cd(II) coordination polymers (CPs), formulated as [Cd(L1)(Formamide)2]n (1) and [Cd2(L2)2(MeOH)2]n (2), by the solvothermal reactions of Cd(NO3)2·4H2O with the anthracene and pyrene group bearing carboxylic acids 5-{(anthracen-9-ylmethyl)amino}isophthalic acid (H2L1) and 5-{(pyren-1-ylmethyl)amino}isophthalic acid (H2L2), respectively. The newly synthesized CPs were characterized by FT-IR, elemental, thermogravimetry and single-crystal and powder X-ray diffraction analyses. The single-crystal X-ray diffraction analysis demonstrates that CPs 1 and 2 have one-dimensional double chain and two-dimensional structures, respectively. These novel CPs were employed for the adsorptive removal of various toxic cationic and anionic organic dyes in aqueous medium. Both CPs are highly effective for the removal of cationic dyes in comparison to anionic ones. However, the two-dimensional pyrene group containing CP 2 shows a higher efficiency (removal efficiency of 75–97 %) in removing three different 6 × 10−5 M cationic dyes. In addition, the adsorption kinetics and isotherms for both CPs were determined. An insight into the removal of the organic dyes is provided by in silico studies. Moreover, the stability and recyclability of both CPs were tested under adsorption conditions.

Photocatalytic Degradation of Organic Dyes in Aqueous Media Under Visible - Light Irradiation Using Aurivillius – Type Bicrvox Catalysts: Development of New Efficient Photocatalysts for Environmental Applications

Photocatalytic Degradation of Organic Dyes in Aqueous Media Under Visible - Light Irradiation Using Aurivillius – Type Bicrvox Catalysts: Development of New Efficient Photocatalysts for Environmental Applications

CdTe/CdS Core–Shell Quantum Dots: Synthesis and Applications as a Heavy Metal Ion's Fluorescence Sensor and Photocatalyst for Photodegradation of Organic Dyes

Herein, a simple method for the growth of the CdS shell around CdTe QDs and the formation of the CdTe/CdS core–shell structure is proposed. The synthesized QDs are characterized using Raman, Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), transmission electron microscopy (TEM), photoluminescence (PL), and UV–vis analyses. XRD patterns confirm the formation of a core–shell‐type structure and particle sizes, lattice strain (ε), and displacement density (δ) are calculated using Williamson–Hall (W–H) and Williamson–Smallman (W–S) approaches. Obtained results show that the CdTe/CdS QDs are spherical with an average crystal size about 5.41 nm. In this work, derivation of absorption spectrum fitting (DASF) is used for the determination of the optical bandgap of the prepared QDs. Prepared CdTe/CdS QDs are applied for the detection of the heavy metal ions and photodegradation of the different organic dyes in aqueous media. The prepared QDs show good performance for the detection of mercury ions (Hg2+) in water with superior selectivity and for photodegradation of the methylene orange (MO) under UV light. The comparison of the obtained results for CdTe/CdS with bare CdTe QDs shows that the core–shell CdTe/CdS QDs have higher sensitivity and enhanced photocatalyst properties compared to the CdTe QDs.

Spinel-Ferrite-Decorated Graphene-Based Nanocomposites for Enhanced Photocatalytic Detoxification of Organic Dyes in Aqueous Medium: A Review

The contamination of organic dye molecules in aquatic environments caused by the effluents released from vast industrial establishments has been a matter of serious concern in recent years, owing to their strong non-biodegradable nature and acute toxicity. Semiconductor-mediated visible-light-driven photocatalytic-dye detoxification is considered as a sustainable technique because it abundantly utilizes the available solar energy and releases environmentally friendly chemicals such as H2O as byproducts. Adequate textural and microstructural properties, an extended visible-light response, pronounced isolation and transfer of photoinduced charge carriers, and facile magnetic-separation characteristics make spinel-ferrite-decorated graphene or its analogues’ (GO/rGO) nanocomposites (MFGNs) a versatile photocatalytic system for the efficacious detoxification of dyes. Therefore, this review article emphasizes their exceptional photodegradation performance in terms of systematic studies of the above-mentioned features, after a brief description of the synthesis protocols. The mechanism of the photodetoxification of dyes over MFGNs is precisely demonstrated in three different sections based on their redox abilities. The kinetics of the MFGN-driven photodecomposition of dyes are then highlighted. We discuss the role of different parameters such as pH, temperature, catalyst dose, and dye concentration in augmented photocatalytic-dye-degradation reactions. Finally, the emerging challenges that act as hurdles in achieving superior photocatalytic-dye-detoxification performance are addressed, along with the conclusion. We then propose some possible future research directions in order to overcome these challenges, for impressively accomplishing the photodegradation of organic dyes.

Catalytic degradation of methyl orange using bimetallic nanoparticles loaded into poly(N-isopropylmethacrylamide) microgels

The health of living organisms is greatly endangered by the rising concentration of hazardous substances in water, such as organic dyes. A catalytic system containing bimetallic nanoparticles loaded in polymer microgels was designed to degrade the organic dyes in aqueous medium. First, the poly( N -isopropylmethacrylamide) [P(NM)] microgel particles were synthesized using free radical precipitation polymerization method, and then Ag/Co nanoparticles were incorporated into the crosslinked network of P(NM) using the in-situ reduction via NaBH 4 . The P(NM) microgels and Ag/Co nanoparticles encapsulated in P(NM) microgels were characterized by TGA, FTIR, EDX, UV-Vis. and STEM results. The catalytic efficiency of Ag/Co-P(NM) towards degradation of methyl orange (MeOr) was evaluated under various reaction conditions. It was found that Ag/Co-P(NM) had remarkable catalytic efficiency. The catalytic efficiency of Ag/Co-P(NM) was found to be 90% even after recycling process. • The silver and cobalt nanoparticles loaded into microgels have been synthesized successfully. • Catalytic activity of metal nanoparticles loaded microgels were also studied in detail. • pH responsive behavior of hybrid microgels was also studied. • Catalytic efficiency of Ag/Co nanoparticles loaded microgels was observed after recycling.

Biogenic synthesis of Bi2O3 nanoparticles using Cassia fistula plant pod extract for the effective degradation of organic dyes in aqueous medium

Biogenic synthesis of Bi2O3 nanoparticles using Cassia fistula plant pod extract for the effective degradation of organic dyes in aqueous medium

Reduction of Toxic Organic Dyes in Aqueous Media Using N-Heterocyclic Copper(II) Complex Immobilized on the Beta-Cyclodextrin-Modified Fe3O4 Nanoparticles as a Magnetically Recyclable Catalyst

Reduction of Toxic Organic Dyes in Aqueous Media Using N-Heterocyclic Copper(II) Complex Immobilized on the Beta-Cyclodextrin-Modified Fe3O4 Nanoparticles as a Magnetically Recyclable Catalyst

Synthesis, characterization, and application of MOF@clay composite as a visible light-driven photocatalyst for Rhodamine B degradation

Metal Organic Frameworks (MOFs) with natural clay materials is a relatively new research avenue that appears to reduce high production costs and address the instability issues of pure MOFs. A novel MOF and natural clay composites of MOF@Sp_n (n = 1–4) were fabricated by the in situ precipitation of stable MOF, Zr6O4(OH)4 (ABDC)6 (where ABDC = 2-aminobenzene-1,4-dicarboxylic acid), over natural sepiolite (Sp) clay and used as a photocatalysts for elimination of organic dyes in aqueous media. The formation of MOF@Sp_n due to its strong electrostatic interactions between the positively charged MOF and the negatively charged sepiolite. Optimizing the Sp content in the composite strongly influenced the dispersibility, crystallinity of MOFs, resulting in progressively functional hybrid materials with an excellent optoelectronic properties. The composites lessened the shortcomings of the individual components and made them suitable as a visible light-active, highly efficient, standalone photocatalyst material that can degrade RhB.

Photocatalytic Decomposition of Organic Dyes Using a Rotating Cylinder System.

In this study, a rotating cylinder system was used in the photocatalytic decomposition of organic dyes in aqueous medium for water purification. To this end, the titania nanoparticle dispersion was mixed with an organic dye solution under a rotating inner cylinder at controlled speed. The rate constant was adjusted by changing the speed of rotation to determine the optimal circulating velocity. Since nanoparticle dispersion is a secondary contaminant after wastewater treatment, the titania paste was deposited on the inner surface of the stationary outer cylinder to form a photocatalytic film. During repeated batch-mode operation, the deactivation of the deposited film was analyzed by measuring the rate constant as a function of time. Continuous operation was also used to remove organic dye in the water to study factors affecting the removal efficiency of methylene blue. Higher rotating velocity and slow feed rate facilitated the removal of contaminants via desorption of adsorbed dyes with adequate retention time.

Self-assembled lignosulfonate-inorganic hybrid nanoflowers and their application in catalytic reduction of methylene blue and 4-nitrophenol

• Synthesis of hierarchical copper phosphate-lignosulfonate (Cu-LS) nanoflowers. • Structural confirmation of Cu-LS nanoflowers by FTIR, BET, XRD, SEM, elemental mapping and EDS analyses. • Catalytic performance of Cu-LS nanoflowers in the reduction of 4-NP and MB in aqueous media. • Cu-LS nanoflowers can be reused five times without any remarkable loss of catalytic activity. Hierarchical inorganic-organic nanostructures prepared using biosourced compounds have attracted a large amount of interest owing to their unique structure, good stability and potential applications. This study was undertaken to design efficient and green hierarchical copper phosphate-lignosulfonate (Cu-LS) nanoflowers with high catalytic sites by an eco-friendly self-assembly method for application in the catalytic reduction of organic dyes in aqueous media. The lignosulfonate played a critical role in controlling the size and morphology of Cu-LS nanoflowers. Moreover, catalytic tests showed the excellent catalytic degradation activity of Cu-LS nanoflowers toward methylene blue (MB) and 4-nitrophenol (4-NP) in the presence of NaBH 4 . In addition, the recycling tests showed the high stability and reusability of Cu-LS nanoflowers for at least five cycles with almost constant catalytic performance. This work presents new insights into the fabrication of lignin based catalysts with sustainable biomass derived components to degrade organic pollutants from aqueous solutions efficiently.

Synthesis and characterization of SnO2 NPs for photodegradation of eriochrome black-T using response surface methodology.

The domestic and industrial sewage contains an extensive range of various organic compounds. Due to the toxicity of these materials, their degradation is considered one of the great environmental challenges. To address this problem, SnO2 nanoparticles (NPs) were synthesized via a green route, and they were used as an efficient catalyst for the degradation of an organic dye. In the stage of synthesis of nanoparticles, Thymus vulgaris L. extract acted as an efficient capping agent and renewable reducing agent, and SnO2 NPs were synthesized without addition of any hazardous surfactants. The successful synthesis of SnO2 NPs was confirmed by XRD, FT-IR, SEM, EDX, and TEM. The photocatalytic performance of SnO2 NPs was examined for the degradation of eriochrome black-T (ECBT) as a toxic organic dye in aqueous medium under ultraviolet irradiation. Furthermore, the response surface methodology (RSM) with central composite design (CCD) model was carried out to study of the effects of three different operational parameters on degradation of ECBT. In this design, initial pH of solution (3-11), reaction time (0.5-4h), and the catalyst loading (0.05-0.12g) were selected as three factors, whereas the degradation efficiency was chosen as the response. The results of the experimental design indicated that initial pH and catalyst loading were highly significant factors, whereas the reaction time was less important than other factors. Also, recyclability of catalyst was investigated, and the obtained results showed that SnO2 NPs could be easily recovered and reused for at least 4 cycles without any significant decrease in their activity.

Facile and fast preparation of Nano-rod ZnO for photocatalytic application under low intensity of UV light irradiation

Objective: This study aims to degrade the organic dyes in aqueous medium and low UV intensity by nano-rod ZnO. Methodology: The ZnO was prepared by a facile and fast method, as-synthesized ZnO was characterized by SEM,XRD, N2 adsorption/desorption isotherm, and diffuse reflectance UV-vis. The composition of samples before and after calcination steps was analyzed by XRD. The catalytic performance of ZnO was evaluated by the degradation of dyes in aqueous solution under a low UV light irradiation. Finding: the precursor was completely transformed to ZnO at 400 ◦C. The ZnO was nanorod structure with the crystalline phase of hexagonal wurtzite. The degradation efficiency of ZnO for Janus Green B in 10 min was 96.8%, it was 95.8% in 40 min for Congo Red. The reaction kinetic of photodegradation of dyes was followed by the first-order kinetic model and the photodegradation mechanism of ZnO for dyes was proposed. Application/Improvement: The facile and fast method was developed for the synthesis of nano-rod ZnO, it could be applied for practical application in wastewater treatment. Keywords: ZnO; dyes; photocatalyst; first-order kinetic; Nano-rod

Efficient and selective adsorption and separation of methylene blue (MB) from mixture of dyes in aqueous environment employing a Cu(II) based metal organic framework

In view of the increasing demand of the better adsorbents for separation of organic aromatic pollutants from waste water, we have made an attempt to design a stable polymeric material for the purpose. In this report, a copper based metal organic framework (MOF), [Cu2(Hbtc)2(H2O)2(µ2-H2O)]H2O (Cu-btc-1), where H3btc = benzene-1,2,4-tricarboxylic acid is synthesized employing one pot solvothermal method. The crystalline material, Cu-btc-1 is characterized by single crystal X-ray, XRPD, TGA and various spectroscopic techniques. X-ray data confirm that Cu(II) is present in square pyramidal environment. Topological features reveal the hxl topology of the MOF. The present MOF (Cu-btc-1) is water stable and recyclable and therefore has been employed in adsorption and separation of methylene blue with excellent efficiency from the mixture of three organic dyes, methylene blue (MB), methyl orange (MO) and rhodamine (Rh-B) in aqueous phase. MB was observed to show highest adsorption of nearly 98% at neutral pH and optimum temperature (25 °C). At equilibrium, the removal efficiency of Cu-btc-1 towards MB from the mixture of dyes was found to be 98.67%. The efficiency and highest adsorption of MB could be attributed to the cationic nature of the dye and nucleophilic aromatic moieties of carboxylates of Cu-btc-1 framework where strong electrostatic interactions take place for adoption of the MB+ molecules. Not only the cationic nature but also the linearity of the MB helps enhance its adsorption by the adsorbent by easily approaching to the sites available on MOF. H-bonding and π–π interactions are also responsible for the adsorption of the dye molecules here. Thus, mechanism of adsorption is the result of interplay of the electrostatic attraction/repulsion, π–π interactions, H-bonding and weak Van der Waals interactions. The present MOF thus represents an excellent class of adsorbent material and establishes a fine tuning between the structure-efficiency relationships for separation of the aromatic organic dyes in aqueous medium for future endeavours.

Synthesis of Porous Silica Particles for the Adsorption of Organic Dye in Aqueous Medium

This study investigated the removal of the organic dye like methylene blue using porous particles in a batch adsorption process. Porous silica microparticles were synthesized with macropores or meso-macropores and used as adsorbent particles. The hierarchically porous structures with additional mesopores were found to be more effective adsorbent than simple macroporous particles. The size of the macropores affected the adsorption capacity of the porous particles, and smaller pore size resulted in a larger amount of organic dye being adsorbed on the particle surface, due to increased surface area. Silica microparticles with wrinkled surfaces were also tested, and their adsorption capacities were studied in relation to their morphologies. Unlike previous studies using mesoporous silica as adsorbents, in this study the methylene blue adsorption kinetics could be explained by the second to fourth order reaction, implying that faster removal of dye molecules is possible compared to photocatalytic reactions, with first order kinetics. The higher order kinetics can be advantageous, providing a faster removal rate, compared to the conventional photocatalytic removal of dyes and other adsorbents.

Hybridization between cellulose nanofibrils and faceted silver nanoparticles used with surface enhanced Raman scattering for trace dye detection

This research studies the surface enhanced Raman scattering (SERS) activity of cellulose nanofibrils (CNFs) hybridized with faceted silver nanoparticles (AgFNPs) for the detection of organic dyes in aqueous media. Faceted AgNPs were synthesized under environmentally benign conditions using TEMPO-oxidized CNFs as both shape-regulating, reducing and stabilizing agents. Small, zero valent, spherical AgNPs first formed on the CNF surface and transformed into larger and faceted AgNPs when reacting with H2O2 through a thermodynamically driven Ostwald ripening mechanism. The as-synthesized hybrids exhibited strong analytical enhancement in the Raman signal of methylene blue, up to 6.8 × 103 at 448 cm−1 with less than 32% spatial variations and 10% sample-to-sample variability, enabling the detection of dyes in water at the sub part-per million level. The origin of the SERS enhancement came from discrete hotspots of high silver content on the substrate, as characterized by spatially resolved laser ablation inductively coupled plasma mass spectrometry.

Direct growth of ZnO nanowires on civil engineering materials: smart materials for supported photodegradation

Photocatalysis is one of the most promising processes for treating air and water pollution. Innovative civil engineering materials for environmental depollution by photocatalysis have already been synthesized by incorporating TiO2 or ZnO nanoparticles in cement. This method suffers from two flaws: first, most of the NPs are incorporated into the cement and useless for photocatalysis; second, rain and wind could spread the potentially carcinogenic nanoparticles from the cement surface into nature. Thus, we propose the efficient synthesis of nontoxic and biocompatible ZnO nanostructures solely onto the surface of commercially available concrete and tiling pavements by a low-cost and low-temperature hydrothermal method. Our samples exhibited enhanced photocatalytic activity for degrading organic dyes in aqueous media, and dye molecules are commonly used in the pharmaceutical, food, and textile industries. Durability studies showed no loss of efficiency after four photocatalysis experiments. Such supported structures, which are easy to implement onto the varying surfaces of commercially available materials, are promising for integration into civil engineering surfaces for environmental depollution in our daily life.

Immobilization of Cr-MIL-101 over the NiO/13X zeolite nanocomposite towards ultrasound-assisted destruction of organic dyes in aqueous media

The present research focuses on the fabrication and application of the Cr-MIL-101@NiO/13X as a novel sonocatalyst nanocomposite. The characterization study of the prepared samples was carried out by employing techniques including FTIR, XRD, FESEM, AFM, EDAX, and X-ray dot-mapping. The fabricated nanocomposite was applied for the sonodestruction of organic dyes in the aqueous media. All of the dependent reactions were performed under the optimized conditions following by the UV–vis analysis to monitor the destruction progress. The extent of sonocatalytic potency of the Cr-MIL-101@NiO/13X nanocomposite was investigated versus the H2O2-associated destruction of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) as prevalent organic dyes under the ultrasonic irradiation. In addition, several influential parameters such as contact time, initial dye concentration, catalyst amount, H2O2 concentration, scavenger type, and process type and their impact on the destruction of the MB, RhB and MO were evaluated. Also employing the first order model, the reaction kinetic was surveyed. The values of 0.0323 min−1 and 21.4551 min were attained for the rate constant (k) and the half-life (t1/2) for the destruction of MB in the Cr-MIL-101@NiO/13X/US/H2O2 system. Moreover, considering the gathered details, the significant performance of OH as a radical scavenger emanated from H2O2 during sonocatalytic destruction procedure is vividly proved. Besides, to challenge the destruction potential of the new nanocomposite and to show the effective combination of its components, the sonocatalytic function of the bare 13X and NiO/13X were studied under the equivalent conditions and the subsequent results were precisely reported.