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Organic dyes can inflict environmental harm and pose risks to human health, thereby presenting challenges in their treatment within industrial wastewater. Currently, numerous research groups have conducted investigations on the adsorption of organic dyes in industrial wastewater. Herein, this work focuses on the selective adsorption approach towards dyes molecules based on an Anderson-type polyoxometalate (noted as POM-1) as potential adsorbent, which has been functionalized with organic ligands to enhance its negative charge. Adsorption experiments revealed that POM-1 displayed efficient adsorption capabilities towards the cationic dye methyl blue with almost complete adsorption within 25 min, and the adsorption rate was calculated as 98%. A rapid and consecutive filtering experiments have also been performed and further proved the excellent adsorption behavior of POM-1 towards MB. [ABSTRACT FROM AUTHOR]

The research article introduces the unexplored synergistic effect of amorphous titanium dioxide and phosphorus-doped carbon nanodot hybrid [C-TiO2(am)] for the ultrafast adsorption of methylene blue and crystal violet dyes. The hybrid eliminates 98% of methylene blue dye (MB) at a concentration of 32 mg/L and 96% of crystal violet dye at a concentration of 62 mg/L from the aqueous solution within 5 min of contact time at ambient temperature. The incorporation of phosphorus-doped carbon nanodot in amorphous TiO2 modifies the oxygen vacancy, which enhances the material's affinity for organic dyes like MB and crystal violet. The significance of defects on the adsorption efficiency of C-TiO2 (am) is obtained and compared with that of amorphous titanium dioxide [TiO2(am)] and the crystalline phase of hybrid (C-TiO2). The dye removal percentages of TiO2 (am) and C-TiO2 are ca.3% and ca.32%, respectively, which is feeble compared to the dye removal percentage of C-TiO2 (am) (ca. 98%). The possible mechanism of organic dye adsorption of C-TiO2 (am) is derived through the detailed discussion of porosity, morphology, functional groups, and chemical compositions. The impact of temperature on dye adsorption and removal rate is determined using non-linear regression analysis. The remarkable characteristic adsorption features of C-TiO2 (am) suggest that it can be considered as a new potential adsorbent for water purification. The remarkable characteristic adsorption features of C-TiO2 (am) suggest that it can be considered as a new potential adsorbent for water purification. [ABSTRACT FROM AUTHOR]

Dye pollution resulting from the discharge of untreated wastewater has become a major environmental concern. In this study, we propose a green and cost-effective approach for the photocatalytic degradation of dye pollutants using a nanocomposite (NC) of manganese oxide (Mn3O4) modified with polyvinylpyrrolidone (PVP). The Mn3O4 nanoparticles (NPs) were synthesized through a green method using a biogenic extract of Pistacia lentiscus leaves. The resulting Mn3O4 NPs were then modified with PVP, a non-ionic polymer, to enhance their stability and catalytic performance. The synthesized Mn3O4/PVP NC was characterized using various analytical techniques, including Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy. The findings showed that the Mn3O4 NPs and Mn3O4/PPV NC exhibit spherical morphology with an average size of 37 nm and 45 nm, respectively. The Mn3O4 NPs and Mn3O4/PVP NC exhibited optical bandgap energies of 1.8 eV and 1 eV, indicating the effective use of these NPs as photocatalysts. The nanocomposite exhibited exceptional catalytic performance in degrading bromophenol blue (BPB) and ortho-toluidine blue (O-TB), achieving degradation rates of 98% and 95% within 75 minutes. In comparison, Mn3O4 NPs showed lower efficiencies with approximately 14% degradation for BPB and 6% for O-TB. Optimal conditions for dye degradation and subsequent cycles were determined, and first-principles calculations revealed insight into the adsorption energy between the dyes and the Mn3O4/PVP surface. This study highlights the potential of Mn3O4/PVP nanocomposite as an effective and eco-friendly catalyst for dye pollutant degradation, offering a promising solution for wastewater treatment across industries. [ABSTRACT FROM AUTHOR]

This study proposes a new method for producing α-Fe2O3–CuO nanocatalyst that is both cost-effective and ecologically benign. The α-Fe2O3–CuO nanocomposite was prepared via moderate thermal oxidative decomposition of copper hexacyanoferrate. Its structure and surface morphology are affirmed via XRD, SEM, FTIR, EDX, TEM, XPS, and VSM. In the presence of H2O2, α-Fe2O3–CuO is employed as a heterogeneous catalyst to stimulate thermally induced degradation of dyes such as direct violet 4, rhodamine b, and methylene blue. The synergistic effect of Fe2O3 and CuO enhanced the catalytic activity of the nanocomposite compared to Fe2O3 and CuO separately. The effectiveness of DV4 degradation is optimized by evaluating multiple reaction parameters. The reaction rate increased substantially with the temperature, revealing its key role in the degradation process. Higher H2O2 levels and the inclusion of inorganic anions like chloride or nitrate also sped up the degradation process. While sulfate and humic acid, particularly at high doses, slowed it. The mechanism of H2O2 activation on α-Fe2O3–CuO is studied. The measurements of chemical oxygen demand and total organic carbon indicate that all dyes are highly mineralized. The remarkable performance and stability of this nanocomposite in removing diverse dyes render it a promising option for wastewater remedy. [ABSTRACT FROM AUTHOR]

This paper proposes a simple and environmentally friendly method for the green synthesis of SnO2–ZnO/bentonite nanocomposite in the presence of Acroptilon repens flower extract as a reducing and stabilizing agent. The synthesized nanocomposite was characterized using various techniques to investigate their structural properties and morphology. The photocatalytic degradation of the organic dye, eriochrome black-T (EBT) under solar irradiation and in the presence of synthesized nanocomposite was investigated. The results indicated that the nanoparticles were well immobilized onto bentonite as a support with minimum agglomeration. Moreover, the results of photocatalytic reactions showed that SnO2–ZnO/bentonite nanocomposite could remove the dyes in just 2.5 h and the degradation efficiencies approached 100% indicating the excellent performance of the catalyst. The kinetic study revealed that degradation of EBT in presence of the SnO2–ZnO/bentonite nanocomposite obeys first-order kinetics with the rate constant of 1.75 × 10–2 min−1. Furthermore, the biosynthesized nanocomposite exhibited a stable performance and high tolerance to the reaction conditions and was reused in three cycles with negligible loss of activity. [ABSTRACT FROM AUTHOR]

Present study reports the hydrothermal synthesis procedure to prepare the facile and sustainable orthorhombic Molybdenum trioxide (α-MoO3) nanoparticles (NPs) for the degradation of thymol blue dye. Synthesized α-MoO3NPs was characterized by FTIR, XRD, Zeta-potential, SEM, and TEM to investigate the functionalities, texture, size, and morphology of α-MoO3 NPs. The average size was calculated up to 68 ± 5 nm. The α-MoO3NPs was successfully applied to degrade toxic organic dye (thymol blue) in aqueous media. To achieve maximum percentage degredation of dye different parameters were optimized, including a catalyst dose, reaction time, effect of microwave irradiation at low power, reproducibility of catalyst. At optimum conditions, the fabricated α-MoO3NPs-based heterogeneous nano-catalyst was highly efficient for degrading thymol blue dye in aqueous media; the percentage degradation was obtained up to 99% within 60 s just using 120 µg of α-MoO3NPs was used under the microwave radiations. The heterogeneous nano-catalyst shows excellent performance and is highly efficient as compared to previously reported work. The schematic diagram for the degradation of thymol blue dye using prepared MoO3 nano-catalyst [ABSTRACT FROM AUTHOR]

The broad application of organic dyes such as 4-nitrophenol (4-NP), rhodamine 6G (R6G), and methylene blue (MB) as raw materials in the manufacture of dyes, explosives, pesticides, preservatives, and pharmaceuticals caused serious damage to the environment, particularly aquatic ecosystems. In this study, silver nanoparticles decorated ZnO/Fe3O4 (Ag/ZnO/Fe3O4) nanocomposite was used as a catalyst to reduce 4-NP, R6G, and MB in the presence of sodium borohydride as a reducing agent. Silver nanoparticles decorated ZnO/Fe3O4 composite was synthesized via a simple and inexpensive chemical reduction method. Scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD) were used to characterize the particles. The surface-enhanced Raman spectroscopy (SERS) activity of the nanocomposites due to AgNPs was used to monitor catalytic reactions with detailed spectral features using SERS. Thus, the catalytic transformation of 4-nitrothiophenol (4-NTP) into 4-aminothiophenol (4-ATP) was traced using SERS. The magnetic property of the nanocomposites enables its repeated use. Easy recovery of the particles from the reaction solution was achieved and run for fifteen cycles with no significant loss of its efficiency. [ABSTRACT FROM AUTHOR]

In this paper, a comparative study about the photocatalytic performance of pure Anatase/Rutile mixed-phase Titania (AR-TiO2) nanoparticles and their nanocomposites with multi-walled Carbon Nanotubes (MWCNTs) & 'Platinum-like' Tungsten Carbide (WC) has been carried out. Nanostructured amorphous-titania was synthesized through the Sol–gel route followed by its crystallization through calcination at ~ 550 °C, while the MWCNTs-TiO2 and WC-TiO2 nanocomposites were produced by the Bath Ultrasonication of their individual aqueous mixtures with the AR-TiO2 nanoparticles. These nanocatalysts were further characterized using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), UV–Visible Spectrophotometry, and Photocatalytic decomposition testing using Methylene Blue (MB) dye. The XRD-based structural examinations determined the occurrence of anatase/rutile mixed phases of titania in all nanocatalysts alongside the MWCNTs and WC in their relevant nanocomposites having connected through physical means only. The chemical analysis was conducted through the FT-IR which also confirmed that there are no chemical interactions in-between the constituents of nanocomposites. The SEM-based morphological studies revealed that the AR-TiO2 nanoparticles were spherical in shape, having average sizes of ≈ 20 nm which were forming flower-like structures around the ends of MWCNTs and were making agglomerates in MWCNTs-TiO2 and WC-TiO2 nanocomposites, respectively. The Optical bandgaps (Eg) were measured through UV–Visible spectrophotometry where the Eg of AR-TiO2 nanoparticles (~ 2.69 eV) was decreased by the mixing of MWCNTs (~ 2.56 eV) while an increasing trend was found with the WC addition (~ 2.75 eV). Finally, the photocatalytic studies showed that MWCNTs-TiO2 and WC-TiO2 nanocomposites have higher efficiencies than the pure AR-TiO2 nanoparticles in the visible and UV-A (λ ~ 366 nm) ranges, respectively. [ABSTRACT FROM AUTHOR]

A novel n-MgFe2O4–n-ZnS heterojunction catalyst was employed via two step approach for photodegradation of organic dyes such as Methylene Blue (MB) and Crystal Violet (CV) dyes under visible light irradiation. The synthesized MgFe2O4/ZnS NCs were characterized using PXRD, FTIR, UV–Visible spectroscopy, PL and FESEM analysis which reveals the formation of flake like structure with size as to be ~ 50 nm. The photocatalytic experimental result demonstrates that the MgFe2O4/ZnS nanocomposites (NCs) improve photodegradation performance with 98.0% and 91% decomposition of MB and CV dyes within 120 min illumination during simulated visible light irradiation. From the result, MgFe2O4/ZnS NCs has higher photocatalytic performance than that of MgFe2O4, and ZnS due to efficient separation of the photo-induced electron–hole pairs and effective electron–hole generation transfer by the formation of n-MgFe2O4–n-ZnS heterojunction. Hence, photodegradation performance implies that the synthesized MgFe2O4/ZnS NCs can be effectively utilized in waste water purification systems. [ABSTRACT FROM AUTHOR]

We report here the utility of Sida acuta Burm. f. root extract-mediated silver nanoparticles in catalytic degradation of organic dyes such as methyl orange (MO), methylene blue (MB), bromophenol blue (BPB), and congo red (CR) in the presence of NaBH4. Monodispersed nanosilver particles were characterized using UV–Visible spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering particle size-zeta potential analysis (DLS-Zeta) and fourier transform infrared spectroscopy (FTIR). TEM images demonstrated spherical uniform nanocrystals (10–50 nm). Catalytic removal of dyes by time-stable AgNPs was studied in a time-dependent manner. Reactions displayed pseudo-first-order rate and rate constants were figured out for removal of different dyes by the nanocatalyst. The dye removal ability of genetically transformed 'hairy root' nanoparticles (HR-AgNPs) was more pronounced in comparison with that by nanoparticles prepared from natural root extract (NR-AgNPs). Efficiency of degrading MO, MB, BPB and CR, to the extent as high as 85.99%, 79.10%, 82.65% and 70.12%, respectively were achieved in 30 min by employing HR-AgNPs; the rate constants being 0.0812, 0.0616, 0.0646, and 0.0498 min−1, respectively. This adsorptive removal ability of such biogenic nanoparticles could be explored in wastewater treatment for removal of toxic pollutant dyes. [ABSTRACT FROM AUTHOR]

A highly stable three-dimensional (3D) silver chloride cluster based coordination polymer (CP) with diphosphines ligand with the formula of [Ag4Cl4(L)2]n (1) (L = 1,3-bis(diphenylphosphino)propane, bdpp) has been prepared at room temperature. 1 was examined for the removal of Rhodamine B in aqueous solution, exhibiting potential for the removal of contaminants from wastewater. [ABSTRACT FROM AUTHOR]

Herein, eight new donor-π-acceptor organic dyes namely M1–M8 have been theoretically investigated for their potential in optoelectronic properties. The M1–M8 were designed through structural modification of π-conjugated bridge of reference reported molecule IC2. The designed molecules contain Indolo[3,2,1-jk]carbazole as core donor unit and end capped cyanoacrylic acid as acceptor unit. DFT and TDDFT calculations using B3LYP, CAM-B3LYP, ωB97XD and M062X functional were performed to evaluate the photophysical and photovoltaic properties. Results indicate that HOMO–LUMO energy gaps in M1–M8 have been found smaller than IC2. Among all, M7 is a material with lowest energy gap 2.61 eV, red shifted absorption wavelength value 436 nm. Results of the calculated redox potential of the ground state, vertical excitation energy of the dye, oxidation potential of the dye in the excited state, free energy change for electron injection, dye regeneration and open circuit photovoltage and light harvesting efficiency indicates that π-bridges in M1–M8 would show better power conversion efficiency than IC2. Especially, dye M7 with π-bridge 5-(thiazol-5yl)thiazole is found to be the most promising candidate for highly effective DSSCs properties. This theoretical framework may provide new ways for experimentalists to design high-performance DSSCs materials for optoelectronic applications. [ABSTRACT FROM AUTHOR]

The resent work reports synthesis of mixed metal oxides of FeLaO3 and FeNdO3 nanocomposites via Co-precipitation method, as effective photocatalyst. The synthesized metal oxides were characterized by Fourier transfer infrared (FT–IR) spectroscopy; X-ray diffraction pattern, and transmission electron microscopy. Alternating gradient force magnetometer illustrates magnetic behavior of mixed metal oxides of FeLaO3 and FeNdO3 nanocomposites. The photocatalytic property of FeLaO3 and FeNdO3 nanocomposites were evaluated using the photodegradation of methyl violet, and malachite green oxalate under ultraviolet light irradiation at various parameters such as temperature, pH of solution, the concentration of dyes, does of catalysts, and time of illumination of UV light. The results show that these nanocomposites have applicable magnetic and photocatalytic performance. [ABSTRACT FROM AUTHOR]

The present paper reports an unexplored simple, single step and cost effective green process for the preparation of highly stable silver nanoparticles (AgNPs) using Epilobium parviflorum (EP) extract and investigates their catalytic activity towards hazardous organic dyes, congo red (CR), rhodamine B (RhB), methyl orange (MO), methyl red (MR), and colorimetric sensing ability for Hg2+ ions in solutions. Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR–FTIR) studies confirmed the capping and stabilization of the AgNPs by EP extract. X-ray diffraction (XRD) pattern showed face centered cubic structure for the AgNPs. Transmission electron microscopy (TEM) validated that the AgNPs are spherical in shape with narrow size distribution of 5.59 ± 1.12 nm. The results indicate that regardless of their good linear dynamic range (0.5–5.0 µM), detection limit (58.11 nM, 11.62 ppb) and selectivity for the accurate determination of Hg2+ ions, the AgNPs can be attractive choices for wastewater management systems. [ABSTRACT FROM AUTHOR]

The effect of nature of carbazole like groups on polarizability and hyperpolarizability of organic dyes has been investigated in this article. Quantum chemical methodologies are used to compute the electronic structures, UV-visible absorption spectra and non-linear optical response. The computed results indicate that the polarizability, oscillator strength, light harvesting efficiency and hyperpolarizability of isoindigo bridging acceptor (BA4) is greater than that of phthalimide bridging acceptor (BA1). The simulated absorption spectra show that the wavelength of dye with BA4 group is red-shifted as compared to that of dye with BA1 group. These results indicate that the BA4 group can effectively improve the non-linear optical response. These theoretical frameworks might be useful to design other organic dyes as these are the first quantum mechanical models to enhance nonlinearity through BA. Graphical Abstract: Quantum mechanical design based on A-π-CorA-π-A combination to enhance NLO response. [ABSTRACT FROM AUTHOR]

Photocatalytic behavior was investigated for TiO-graphene nanocomposite in the degradation of acid orange 7 (AO7) as a model pollutant under ultraviolet light in aqueous solution. XRD, SEM, TEM, DRS, FT-IR and EDX techniques were used for the characterization of the prepared nanocomposite. The effect of synthesis variables such as weight ratio of TiO to graphene and operational key factors such as initial dye concentration, irradiation time, catalyst dosage and solution distance from UV lamp were studied in the photocatalytic degradation of AO7. This excellent catalytic ability is mainly attributed to the synergic effect of photocatalyst and adsorbent. The effect of operational variables was optimized for the photocatalytic degradation of AO7 as a pollutant model using the RSM technique. In this case, the amount of the determination coefficient (R = 0.97) shows that 97% of the variability in the response could be described by the model. The maximum degradation efficiency (96%) was achieved at the optimum operational conditions: catalyst dosage of 0.5 g L, the irradiation time of 50 min and distance the solution from UV lamp of 0.3 cm. [ABSTRACT FROM AUTHOR]

Over the past few decades, increasing attention has been focused on overcoming the scarcity of fresh water resources, with the rapid effluents of dyes from modern chemical industries causing issues in photosynthetic activity of aquatic organisms. In the process of recycling wastewater, the degradation of dye pollutants such as 4-nitrophenol, methylene blue, and methyl orange has become more crucial. Noble metal (silver, gold, palladium, and platinum) materials have significant potential applications in the areas of water purification, conversion of automobile exhaust emissions, and catalysis. Ultra-small alkylamine-capped palladium nanoparticles (APd NPs) with sizes below 10 nm are synthesized using hexadecylamine (HDA) as a stabilizing material, and HDA can prevent the irreversible aggregation of small-sized nanoparticles in solution-based reactions. The fabricated ultra-small APd NPs are investigated using UV-Vis, XRD, SEM, TEM, FTIR and TGA studies. In the presence of NaBH as a reducing agent, the APd NPs achieve high catalytic performance toward the degradation of dye pollutants such as 4-nitrophenol, methylene blue and methyl orange. Graphical Abstract: Catalytic activity of alkylamine capped palladium nanoparticles for organic pollutant degradation. [ABSTRACT FROM AUTHOR]

In this paper, we develop a facile and convenient two-step strategy for preparation of ZIF-8/ZnO/KPWO (PW) ternary composite materials for the first time. ZIF-8/ZnO are fabricated by a 'direct mixing' synthesis strategy and served as the substrate for subsequent PW deposition. Then, ZIF-8/ZnO/PW ternary composite was prepared in PW aqueous solution through electrostatic interaction process. Further, the composites with different loading of PW were achieved by reacting with different concentration of PW aqueous solution. The as-prepared composite materials were characterized and confirmed by powder X-ray diffraction, TEM, EDS, ICP, FT-IR spectra, UV-Vis diffuse reflectance spectroscopy, and electrochemical test. It is noteworthy that the hybrid composites exhibit high efficient activities in the removal of cationic dyes, which could be ascribed to the high adsorption capacity derived from the strong electrostatic interaction between PW and cationic dyes. Based on the investigation, the composites have potential application for waste water purification. [ABSTRACT FROM AUTHOR]

Applying of the most toxic halogenated and aromatic flame retardants is limited with respect to the environmental requirements. Nontoxic Al(OH) nanoparticles were synthesized via a simple surfactant-free precipitation reaction at room temperature. The effect of various precipitation-agents on the morphology of the products was investigated. Al(OH) nanoparticles were added to the polysulfone and poly styrene (PS) matrices. Electron microscope images show excellent dispersion of aluminium hydroxide in PS matrix. Nanoparticles appropriately enhanced both thermal stability and flame retardant property of the polymeric matrices. The enhancement of flame retardancy is due to endothermic decomposition of Al(OH) that absorbs heat and simultaneously releases of water (makes combustible gases diluted and cold). Dispersed nanoparticles play the role of a barrier layer against flame, oxygen and polymer volatilization. Al(OH) was converted to AlO and its photo-catalyst property in degradation three different organic dyes as pollutants was investigated. [ABSTRACT FROM AUTHOR]

In this study, the iron oxide/silver (FeO/Ag) nanocomposite has been successfully prepared by a facile one-step method using goethite (α-FeOOH) rods as support. The diameter of the as-synthesized goethite rods was between 250 and 500 nm and the silver nanoparticles sizes were about 10-50 nm. By varying the concentrations, the FeO/Ag nanocomposite with different Ag contents are successfully obtained. The FeO/Ag nanocomposite was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy dispersive spectroscopy, respectively. Due to the unique nanostructure, these nanocomposites can catalyze degradation of both aromatic nitro compounds and organic dyes only within a few minutes, which show high catalytic performance. [ABSTRACT FROM AUTHOR]

Effect of triethanolamine, n-octylamine, starch, polyethylene glycol and hexadecyltrimethylammonium bromide as template have been investigated on the formation of Bi2O3 prepared via sol gel method. The prepared catalysts were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared, UV–visible diffuse reflectance and Brunauer–Emmett–Teller techniques and subsequently used as photodegradation catalyst to purify contaminated water by Congo red and methylene blue as phenolic dyes. It was found that whereas Bi2O3-starch, Bi2O3-CTAB and Bi2O3-PEG have the most photodegradation effect on methylene blue under visible irradiation, Bi2O3-starch and Bi2O3-CTAB are the most active catalysts for Congo red under UV irradiation. In other word, the type of organic dyes, photocatalyst morphologies and templates are important factors on the photodegradation and adsorption phenomena. [ABSTRACT FROM AUTHOR]