Aqueous Dye Research Articles

Synchronized wet-chemical development of 2-dimensional MoS2 and g-C3N4/MoS2 QDs nanocomposite as efficient photocatalysts for detoxification of aqueous dye solutions

The photocatalytic performance of graphitic carbon nitride (g-C3N4) is improved by the introduction of molybdenum disulfide (MoS2) quantum dots (QDs), aiming the enhanced visible light absorbance in resultant 2-dimensional g-C3N4/MoS2, termed as GCN/MoS2 hereafter. A novel synthetic approach i.e., pseudo-successive ionic layer adsorption and reaction (p-SILAR) was employed to deposit MoS2 QDs on g-C3N4 and to salvage 2-dimensional MoS2 concomitantly. The results of the photocatalytic activity affirm that GCN/MoS2 worked as a better photocatalyst than the pure g-C3N4, while salvaged MoS2 also showed reasonable degradation of Rhodamine-B (RhB) dye. The average pore size (measured with BET analysis) of GCN/MoS2 was reduced to 31.91 nm from 33.11 nm (for g-C3N4), indicating effectual nanoscale deposition of MoS2 which resulted in a decrease in the overall bandgap alignment of the composite from 2.8 eV to 2.2 eV. In-depth material characterization and photocatalytic analysis was carried out to affirm that p-SILAR serves as a suitable synthesis route for the development of GCN/MoS2 nanocomposite as well as salvaged MoS2.

Microstructural investigation of sonochemically synthesized Zn substituted CuFe2O4 nanoparticles for heterogeneous green catalytic click chemistry and dye degradation

Heterogeneous green catalysis by means of magnetically separable nanometal–oxide catalysts is an attractive field of present day research. The microstructural characterization, optical and magnetic properties of sonochemically synthesized Zn substituted CuFe2O4 (CZF) nanoparticles (NPs) are investigated and compared with the unsubstituted CuFe2O4. PXRD (powder X-ray diffraction) pattern and HRTEM (high-resolution transmisson electron microscopy) observation with FTIR (Fourier transform infrared) spectroscopy are applied to analyze the microstructural and optical properties of nanosized (∼14.7 nm) zinc substituted copper ferrite. Rietveld refinement of the PXRD pattern reveals the mixed spinel structure of zinc substituted copper ferrite NPs. Magnetic data confirms the presence of ferromagnetic/ferrimagnetic phase with some admixture of finer superparamagnetic (SPM) nanophases within the sample. The lack of saturation in the M-H loops is due to the presence of spin-canting as well as SPM NPs in the system. These coupled Zn substituted CuFe2O4 magnetic NPs are used as a heterogeneous catalyst for three-component Huisgen 1,3-dipolar CuAAC green catalytic click reactions in aqueous media and dye degradation. Its catalytic reactivity has been compared with CuFe2O4 NPs. By this synthesized magnetic catalytic CZF NPs, we have successfully coupled alkyl halides and boronic acids with terminal alkynes to obtain 1,4-disubstituted 1,2,3-triazoles in good to excellent yields within a short time. The Heterogeneity, reproducibility and reusability of the catalyst has been also tested successfully up to several cycles without significant decrease in the product yield. We have explored CZF NPs as magnetically separable heterogeneous green catalyst for multi-component click reaction. Our synthesized CZF NPs has been used as photocatalyst for the photo degradation of organic dyes under visible light irradiation. The results demonstrate that the unique features of the CZF NPs make it an excellent material for a click chemistry catalyst as well as a highly active photocatalyst under visible light irradiation.

Facile construction of cost-effective zinc-aluminium polymeric framework for efficient removal of selective both drug and dye from an aqueous medium

A novel aluminium (Al) and its active alloys are extensively been used in nearly all areas owing to their cost-effectiveness. But when it is subjected to an aqueous medium, gets corroded through a chemical response. In this paper, a novel framework was fabricated by copolymer coating over on Al and loaded with zinc via electro polymerization and electrodeposition method ([EDA- OPDA]Al@Zn). The as-fabricated composite has emerged for the sorption of Methylene Blue (MB) aqueous dye and Paracetomal drug (PAR). The as-fabricated composite framework has been categorized via IR spectra, FE-SEM images, and EDX spectra. The sorption progression was optimized for numerous prompting features like pH, contact time and impact of dosage. Based on kinetics data, the growth in QE value by an enhancement in temperature for adsorption and the higher r values shows the adsorption progression is a pseudo-second-order model. The thermodynamic constraints specify that the field of adsorbate is impulsive and typical endothermic process. Instead, the corrosion resistance of a composite in the 3.5% of NaCl. Solution was explored via EIS spectra and potentio-dynamic polarization. Depending on the observed features, it indicates that the [EDA-OPDA]Al@Zn framework provided fantastic corrosion resistance. So it is obvious that the as-synthesized framework is of multitasking, that it could be successfully performed for the exclusion of MB aqueous dye and PAR drug from the aqueous medium and it also withstands effectively in this corrosive medium.

2D layered MXene/TiO2 nano-heterostructures for photocatalytic H2 generation

It is known that 2D MXene can be oxidized in air to form heterostructures of carbides, carbon, and oxides. We prepared MXene/TiO2 nano-heterostructures by in-situ thermal processing of MXene (Ti3C2Tx) at 250–400 °C temperature range in air. The structural studies by x-ray diffraction indicate the formation of MXene/TiO2 nano-heterostructures with increasing the annealing temperature above 300 °C and the resulting structure became mostly TiO2 after 400 °C annealing with no detectable MXene peaks in XRD patterns. The diffuse reflectance UV–Visible absorbance spectroscopy shows the blue shift in the absorbance profile of MXene from 720 to 380 nm by increasing the temperature. Photoluminescence spectra shows two emission peaks, the emission at 370 nm and 470 nm corresponds to band edge emission and oxygen defect, respectively. Raman analysis also supports the formation of MXene and TiO2 nano-heterostructures. Scanning and transmission microscopy results depict the formation-layered structures of MXene transformed into exfoliated sheet-like structures due to etching. The photocatalytic activity of formed nano-heterostructures was investigated for H2 generation via water splitting and aqueous methylene blue dye degradation. The nano-heterostructure formed at 350 °C conferred highest H2 production (366 μmol/0.1 g) as compared to other prepared compositions having apparent quantum yield (AQY) of 5.9% and shows MB degradation rate of 13.16 × 10–3 min−1.The formation of nano-heterostructures, particle morphology, higher surface area, the presence of remaining MXene might be responsible for higher photocatalytic activity. These MXene-based nano-heterostructures will have potentials along with other semiconductors for enhanced hydrogen production.Graphical abstract Schematic presentation of photocatalytic water splitting using Ti3C2Tx/TiO2 nano-heterostructure.

High-performing PVDF membranes modified by Na+ MMT/ionic liquids (ILs) with different chain lengths: dye adsorption and separation from O/W emulsion

At present, the continuous deterioration of water environment is a serious threat to the sustainable society. Therefore, there is an urgent need for an antifouling film which can remove both dyes and oil/water. Herein, a series of ionic liquids (ILs) with different chain length was prepared to modified Na-montmorillonite (Na+ MMT) and mixed with polyvinylidene fluoride (PVDF) by blending technology. The obtained ILs–Na+ MMT film exhibited excellent hydrophilic performance and separation performance in the separation of dye and emulsion wastewater by phase transformation method. Specifically, we inspected ILs–Na+ MMT film with different chain lengths (C4, C8, C12, C16). Interestingly, the ionic liquid chain length(C12) of modified film showed good antifouling performance, the flux recovery rate for anionic (99.67%) and cationic dyes (98.72%) and bovine serum albumin (BSA) (98.1 %) at a high level as well as high rejection efficiency for oil–water emulsions, the modified films have excellent sustainability after 6 cycles of use (over 89%). In addition, dye flux was increased by 671% compared with pure PVDF membranes, and the waste rate reached 99.99% by dye filtration, indicating that PVDF/ILs-Na+ MMT has potential applications in oily and aqueous dye adsorption fields.

Prebiotic Vesicles Retain Solutes and Grow by Micelle Addition after Brief Cooling below the Membrane Melting Temperature.

Replication of RNA genomes within membrane vesicles may have been a critical step in the development of protocells on the early Earth. Cold temperatures near 0 °C improve the stability of RNA and allow efficient copying, while some climate models suggest a cold early Earth, so the first protocells may have arisen in cold-temperature environments. However, at cold temperatures, saturated fatty acids, which would have been available on the early Earth, form gel-phase membranes that are rigid and restrict mobility within the bilayer. Two primary roles of protocell membranes are to encapsulate solutes and to grow by incorporating additional fatty acids from the environment. We test here whether fatty acid membranes in the gel phase accomplish these roles. We find that gel-phase membranes of 10-carbon amphiphiles near 0 °C encapsulate aqueous dye molecules as efficiently as fluid-phase membranes do, but the contents are released if the aqueous solution is frozen at -20 °C. Gel-phase membranes do not grow measurably by micelle addition, but growth resumes when membranes are warmed above the gel-liquid transition temperature. We find that longer, 12-carbon amphiphiles do not retain encapsulated contents near 0 °C. Together, our results suggest that protocells could have developed within environments that experience temporary cooling below the membrane melting temperature, and that membranes composed of relatively short-chain fatty acids would encapsulate solutes more efficiently as temperatures approached 0 °C.

Environmental friendly silk and cotton dyeing using natural colorant of Bougainvillea (Bougainvillea glabra) flowers: the sustainable approach towards textile industry.

For the current study, Bougainvillea flowers as environment friendly sustainable source of plant-based natural dye have been selected as an alternative to toxic synthetic dyes for dyeing of cotton and silk. Natural colorant from Bougainvillea flowers (Bougainvillea glabra) was extracted using aqueous and acidic extraction media. Maximum colorant was extracted in aqueous medium, and further it was used for cotton and silk dyeing. The optimum values of the dyeing parameters including dyeing time, dye to liquor ratio and salt level as exhausting agent were found to be 30min, 35-mL liquor ratio and 3.0g for cotton and for silk 45min dyeing time, 45-mL liquor ratio and 3.0g exhausting agent in aqueous dye extract. Bio mordanting has been applied to attain a variety of color shades. The utilization of 3% of henna, 4% of turmeric for silk pre-mordanting and for post-mordantingturmeric at 3% and henna at 4% for silk gave a darker shade. Forcotton bio mordanting, 2% turmeric rhizome powder, 3% henna leaves powder extract as pre-mordant and 2% turmeric, 3% henna as post-mordant hasdeveloped a variety of shade. Overall, it has been found that natural colorant from Bougainvillea flowers is the new dye source for bio-colorationof natural fabrics, and addition of bio mordants has made the process more calming and eco-friendly.

Assessment of Colorimetric and Fastness Properties of Prangos Ferulacea (Jashir) Dyed Wool Yarns in Conjunction with Mixed Metal Mordant Combinations via Reflectance Spectroscopy

ABSTRACT Prangos ferulacea (Jashir) plant possesses various phytoconstituents such as coumarins, flavonoids, alkaloids, umbelliferon, and monoterpenes and has been used in traditional medicine. The presence of flavonoids in aerial parts of Prangos ferulacea necessities further examination of using them as a source of natural colorants for developing natural and beautiful shades on wool yarns. This will add one more new effective natural dye source and ease the dependency of the present-day textile industry on synthetic colorants. Simple adsorption of aqueous dye extract on the wool followed by evaluation of buildup properties using 28 different binary metal combinations as mordants were studied in this study. The dyeing was performed by exhaust dyeing method and dyed samples were analyzed through reflectance spectroscopy and analyzed in terms of color strength, CIEL*a*b*, and CIEL*c*ho values. Color characteristics were evaluated on a spectrophotometer under D65 illuminant and 10° standard observer. FT-IR and SEM analyses were performed to characterize P. ferulacea dyed wool yarns. The results showed that overall 29 different shades having very good to excellent fastness properties were produced by the use of different metallic salt combinations in natural dyeing of wool yarns using aerial parts of P. ferulacea as a source of natural dye.

Marginal Microleakage of Glass Ionomer-Based Restorations After Conventional Cavity Preparation and Er: YAG Laser Irradiation

Purpose: This study aimed to evaluate the microleakage of glass ionomer restorations (GIC) in Class V cavities prepared with both conventional and Er: YAG laser techniques. Methods: Twenty teeth were used. Standard Class V cavities (4mm wide,3m high,3mm deep) were prepared on the buccal and lingual surfaces of teeth. All teeth were randomly divided into four groups. In Groups II and IV, cavities were prepared by Er: YAG laser, and in Groups I and III cavities were conventionally prepared with a diamond bur. Groups I and II were then restored with conventional GIC (Ketac,3MEspe, U.S.A.).Groups III and IV were restored with high viscosity GIC with resin coating (EQUIA, GC, Tokyo, Japan). Specimens were stored in distilled water at 37°C for 24h. Teeth were then subjected to thermo-cycling (500 cycles,5°C-55°C). All teeth were exposed to 50.000 cycles in a chewing simulator. Specimens were stained with 0.5% aqueous basic fuchsin dye and sectioned buccolingually. Dye penetration was scored under a stereomicroscope. The data were analyzed by Kruskal-Wallis One-Way ANOVA and Mann-Whitney U tests. Results: While the highest microleakage scores were observed in the group prepared with Er: YAG laser and restored with conventional GIC the lowest microleakage scores were observed in the group prepared with Er: YAG laser and restored with high viscosity GIC. When cavities prepared with Er: YAG laser or conventional method were restored with high viscosity GIC, no statistically significant difference was found between them (p> 0.05). Conclusion: High viscosity GIC can be preferred as a restorative material in the restorations of Class V cavities prepared using both conventional and Er: YAG lasers.

Characteristics and aqueous dye removal ability of novel biosorbents derived from acidic and alkaline one-step ball milling of hickory wood

New classes of biosorbents are needed for various environment remediation applications. Thus, a facile and benign approach to synthesize porous biosorbents was developed using acidic or alkaline one-step ball milling of hickory wood biomass (AcBH and AlBH, respectively) without any external heat treatment, and their properties were compared. AcBH and AlBH were richer in O-containing functional groups, had enhanced porous structure and greater ability to remove crystal violet (CV, 476.4 mg g−1) and Congo red (CR, 221.8 mg g−1) dyes from aqueous solution, respectively, relative to hickory wood ball milled at neutral pH. Freundlich isotherm and pseudo second order kinetic models best fitted CR and CV adsorption onto biosorbents, indicating a mainly surface complexation adsorption mechanism. Further, both sorbents exhibited excellent stability and dye adsorption reusability. These results demonstrate that acidic and alkaline one-step ball milling is a facile and efficient approach for converting wood biomass into environmentally friendly biosorbents.

Eco-friendly acid dyeing of silk and wool fabrics using Acid Violet 49 dye.

The effluent load from textile industries has forced traders and industrialists to use sustainable tools that not only save energy, money, and labor but also make the process cleaner. The purpose of this study is to improve the dyeing of proteinous fabrics using Acid Violet 49 dye under microwave radiation. Aqueous and acidic dye solutions were prepared and treated with MW radiations for up to 10min. MW treated and untreated dye solutions were used to color treated and untreated fabrics to observe color yield. It has been found that dyeing of irradiated silk at 65°C for 35min, using 55mL of irradiated dye solution containing 1g/100mL salt, has given excellent results. Whereas good color characteristics are obtained if irradiated wool fabric is dyed at 85°C for 55min, using 55mL irradiated dye solution using 1g/100mL salt. Physicochemical analysis reveals that MW rays have physically modified the fabric without altering its chemistry. ISO standard methods employed for colorfastness show that under optimal conditions, the color developed is fast; statistical analysis shows that the dyeing process has given significant results. It is concluded that MW rays have excellent potential to improve acidic dyeing of proteinous fabric under mild conditions which show that the utilization of MW rays is a cost-, time-, and energy-effective process.

Photocatalytic Degradation of Magenta Effluent Using Magnetite Doped TiO2 in Solar Parabolic Trough Concentrator

Due to population growth and industrial development consumption of non-renewable energy sources, and consequently pollution, has increased. In order to reduce energy utilisation and preserve the environment, developed and developing countries are increasingly trying to find solutions based on renewable energy sources. Cost-effective wastewater treatment methods using solar energy would significantly ensure effective water source utilisation, thereby contributing towards sustainable development goals. In this paper, special emphasis is given to the use of solar energy as the driving force of the process, as well as the use of highly active magnetic TiO2-based catalysts. Therefore, in this study, we investigated the possibility of photocatalytic degradation of aqueous magenta graphic dye using titanium dioxide as a catalyst and DSD model in order to achieve the best process optimisation. TiO2 was successfully coated with magnetic nanoparticles by one step process and characterized using different techniques (BET, SEM/EDS, FTIR, XRD). Based on DSD statistical method optimal reaction conditions were pH = 6.5; dye concentration 100 mg/L; TiO2–Fe3O4 0.6 g/L, at which the highest degree of magenta dye decolourisation was achieved (85%). Application of solar energy coupled with magnetic TiO2 catalyst which could be recovered and reused makes this approach a promising alternative in green wastewater treatment.

The roles of polymer relaxation phenomena, aqueous dye solubility and the physical properties of water in the mechanism of adsorption of a disperse dye on poly(ethylene terephthalate) fibres: Part 3 physical properties of water and water‐derived fibre properties

AbstractIn the absence of published information regarding the temperature dependency of water‐derived poly(ethylene terephthalate) fibre properties, the findings reported for the thermally regulated interactions between water and 100% amorphous poly(ethylene terephthalate) materials were interpreted from the perspective of the amorphous domains that reside within semi‐crystalline polyester textile fibres. This analysis suggests that the pronounced temperature dependent uptake of a commercial grade disperse dye on poly(ethylene terephthalate) fabric achieved during an aqueous dyeing process at temperatures between 30 and 130°C is the likely result of the combination of three separate, but inherently inter‐related, thermally activated phenomena, namely, polymer structural relaxation, in which polymer glass transition assumes a dominant role, dissolution of disperse dye in the aqueous dyebath, as well as various water–fibre interactions, in the guise of water sorption, water molecule diffusivity, water‐induced swelling and water‐induced plasticisation. Although thermally regulated macromolecular relaxation processes adopt the principal role in dye uptake, temperature dependent dye solubility and water‐derived fibre properties nevertheless likely provide crucially important supportive roles.

Facile synthesis of multifunctional zinc vanadate/polyaniline composite for photocatalytic degradation and supercapacitor applications

Multifunctional Zn3V2O8/Polyaniline (ZnV/PANI) composite was prepared by in-situ oxidative polymerization method. The formation of ZnV and ZnV/PANI composite was proved by various characterization tools including such as FTIR, XRD, SEM, BET, VSM, TEM and XPS analysis. The average crystalline size calculated using Scherrer equation of ZnV and ZnV/PANI were found to be 45 nm and 92 nm respectively. From the Tauc plots the bandgap values (Eg) were found to be 2.4 eV and 2.0 eV for ZnV and ZnV/PANI respectively. The FE-SEM images clearly show the flakes incorporated cluster-like morphology. The BET surface area of ZnV and ZnV/PANI was found to be 22 m2 g−1 and 40 m2 g−1. The XPS results also confirm the successful formation of ZnV/PANI composite. The as-prepared samples were utilized as photocatalyst and electrode materials for energy applications. The ZnV/PANI composite showed an outstanding photocatalytic activity (94%) in the degradation of aqueous RhB dye under visible light irradiation. The optimum catalyst dosage for the degradation of 50 mL of 1 × 10−5 M RhB dye aqueous solution was 50 mg. The Langmuir-Hinselwood (L-H) kinetic model proves that the photodegradation mechanism follows pseudo-first order kinetics. Further, the supercapacitive behavior of the ZnV/PANI composite was tested using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) techniques in 1 M KOH electrolyte at the potential window of 0–0.55 V. ZnV/PANI electrode displayed a specific capacitance (Csp) of 664 F g−1 at 1 A/g. The satisfactory performance of ZnV/PANI composite is mainly ascribed to the synergistic effect of ZnV-PANI matrixes with the occurrence of multiple electroactive sites in the composite. The cycling stability test proved that ZnV/PANI electrode material retained 92% of its initial capacitance even after 6000 GCD cycles at 2 A/g. The finding of this study will help to determine the most efficient and cost-effective method for the removal of dyes from textile industry wastewater and also as an effective material for supercapacitor applications.

Engineering of heterojunction TiO2/CaIn2S4@rGO novel nanocomposite for rapid photodegradation of toxic contaminants

The in-situ reduction of GO to rGO and simultaneous deposition of TiO2 and varying concentrations CaIn2S410 % (rGO-C1), 20 % (rGO-C2), and 40 % (rGO-C3) resulted in the formation of robust photocatalysts for the degradation of aqueous (azo and thiazine) dyes methylene blue (MB), congo red (CR) and real wastewater. Batch experiments were performed to analyse the effect of pH, catalyst dose, initial dye concentration and time. Compared to other synthesised composites, rGO-C2 demonstrated enhanced photodegradation activity, with a degradation efficiency of almost 100 % within 25–30 min. A possible mechanism for the photodegradation of dyes was also proposed, and post-degradation products were analysed using the LC–MS technique. The kinetic studies show that the degradation efficiency of rGO-C2 followed pseudo-first-order reaction kinetics (k = 0.027 min−1. The rGO-C2 photocatalysts demonstrated excellent photocatalytic degradation in real textile industry wastewater and landfill leachate wastewater. It displayed excellent recyclability and stability up to the four-cycle.

Comparative Evaluation of Microleakage of Flowable Composite Resin Using Etch and Rinse, Self-Etch Adhesive Systems, and Self-Adhesive Flowable Composite Resin in Class V Cavities: Confocal Laser Microscopic Study.

The essential factor in determining the preservation of restoration is the marginal seal. Restoring cervical lesions with a resin composite has always been a challenge. Composite resins with various viscosities and different bonding systems are being researched to reduce the microleakage. Confocal laser scanning microscopy (CLSM) is the latest non-destructive technique for visualizing the microleakage. Objectives: To evaluate and compare the microleakage of Universal Flo composite resin (G-aenial) using etch and rinse adhesive system ER-2 steps (Adper Single Bond 2), self-etch adhesive system SE-1 step (G-Bond), and self-adhesive flowable composite resin (Constic) in Class V cavities using a confocal laser scanning microscope. Materials and Method: Class V cavities were prepared on 27 caries-free human extracted premolar teeth on the buccal and lingual surfaces with standardized dimensions of 2 mm height, width 4 mm, and a depth of 2 mm. After the cavity preparation, all teeth were randomly divided into three groups, namely Group-I: G-aenial Universal Flo with Single Bond 2 (n = 9 teeth); Group-II: G- aenial Universal Flo with G-Bond (n = 9 teeth), and Group-III: Constic (n = 9 teeth). The prepared and restored specimens were then subjected to thermocycling for 500 cycles in a water bath at 5 °C and 55 °C with a dwelling time of 30 s. The specimens were placed in 0.6% aqueous rhodamine dye for 48 h. Sectioning was carried out bucco-lingually and specimens were evaluated for microleakage under a confocal laser scanning microscope. Results: There was a significant difference (p = 0.009) in microleakage when comparing total etch and rinse, specifically between Adper Single Bond 2 ER-2 steps (fifth generation) and self-adhesive flowable composite resin, which is Constic. There was more microleakage in the self-etch bonding agent, particularly G-Bond, SE-1 step (seventh generation), when compared to ER-2 steps (fifth generation bonding agent); however, the results were not statistically significant (p = 0.468). The self-adhesive flowable composite resin showed more microleakage than SE-1 step and ER-2 steps. Conclusions: None of the adhesive systems tested were free from microleakage. However, less microleakage was observed in the total etch and rinse, especially Adper Single Bond 2 (ER-2 steps), than the self-etch adhesive system SE-1 step and self-adhesive flowable composite resin. Clinical significance: Constant research and technological advancements are taking place in dentin adhesives to improve the marginal seal. This has led to the evolution of total acid-etching dentin bonding agents termed as etch and rinse (ER)-2 steps (fifth generation dentin bonding agents) and self-etching (SE) 2 steps, and SE-1 step dentin bonding agents termed as the sixth and seventh generation bonding agents, respectively.

Boosting photocatalytic interaction of sulphur doped reduced graphene oxide-based S@rGO/NiS2 nanocomposite for destruction of pathogens and organic pollutant degradation caused by visible light

Semiconductive materials that are activated by solar light and have a low e- and h+ pair recombination rate, a short bandgap, and fast charge carrier characteristics are effective organic pollution treatment catalysts. Synthesizing sulphur doped reduced graphene oxide/NiS2 ([email protected]/NiS2) nanocomposites (NCs) for effective dye-degradation through photocatalysis under solar irradiation is the subject of this paper. [email protected]/NiS2 NCs were made using a simple and efficient [email protected] nanosheets in NiS2 solution technique. When bound to rGO, NiS2 nanoparticles (NPs) act as an effective catalyst for the removal of methylene blue (MB) dye. SEM, EPR, FTIR, UV–vis, photocurrent responses, XRD, and EDX were used to characterize [email protected]/NiS2 NCs. [email protected]/NiS2 is predominantly utilized as a photocatalyst for photoreaction-based degradation of aqueous MB dye. The nanocomposite removes 96 percent of the MB dye in 84 min. The presence of NiS2 NPs in the catalyst increases the formation of hydroxyl radicals (OH), which supports the photocatalytic process by suppressing electron (e-) and hole (h+) recombination, resulting in the destruction of organic contaminants. The catalyst's effectiveness is further tested by altering the pH of the MB solution medium. The reaction rate is pH dependent, with the quickest degradation time in the presence of [email protected]/NiS2 NCs occurring at pH 8. The reusable catalytic characteristics of suspended [email protected]/NiS2 NCs are investigated for six cycles, yielding a degradation efficiency of more than 93 percent in 84 min. Under sunlight, the antibacterial effectiveness of [email protected]/NiS2 was investigated against Gram-positive and Gram-negative microorganisms. These promising findings could be used to purify polluted water from numerous sectors.

Analysis of flower extract and natural dye solution from Sesbania javanica using Fourier-transform infrared spectroscopy (FTIR) chemometrics, and determination of its antioxidant and anti-glucosidase activities

Fourier-transform infrared spectroscopy (FTIR) chemometrics and determination of antioxidant and anti-glucosidase activities of flower extract and natural dye solution from Sesbania javanica were performed. Total phenolic content and total flavonoid content were the highest in ethanolic flower extract, while antioxidant activity (1/EC50 = 0.4935) and α-glucosidase inhibition (1/EC50 = 2.9671) were the highest in dye solution, obtained from mixing white clay filler with aqueous dye extract. The correlations of FTIR data, bioactive compound contents, and biological activities were assessed by partial least squares structural equation modelling. Results showed that a strongly positive relationship was significantly demonstrated between FTIR fingerprints and bioactive compound contents (β = 0.825, t = 17.037, p value < 0.05), and between bioactive compound contents and biological activities (β = 0.563, t = 3.000, p value < 0.05). However, a strongly negative relationship was significantly found between FTIR fingerprints and biological activities (β = -1.204, t = 6.065, p value < 0.05). Moreover, the PCA and cluster analysis from FTIR data led to well grouping in PC plots and phylogenetic trees. Interestingly, the PCA and cluster analysis from FTIR data of plant extracts in powdered form provided better separation in PC plots and phylogenetic trees than in liquid form.

Thiourea-Isocyanate-Based Covalent Organic Frameworks with Tunable Surface Charge and Surface Area for Methylene Blue and Methyl Orange Removal from Aqueous Media.

A thiourea hexamethylene diisocyanate covalent organic framework (TH COF) was synthesized by adjusting the surface charge and surface area. The surface charge value of TH COF, −3.8 ± 0.5 mV, can be changed to −29.1 ± 0.4 mV by treatment with NaOH (dp-TH) and 17.1 ± 1.0 mV by treatment with HCl (p-TH). Additionally, the surface area of TH COF was 39.3 m2/g, whereas the surface area of dp-TH COF and p-TH COF structures were measured as 41.4 m2/g and 42.5 m2/g, respectively. However, the COF structure had a better adsorption capability with acid and base treatments, e.g., dp-TH COF absorbed 5.5 ± 0.3 mg/g methylene blue (MB) dye, and p-TH COF absorbed 25.9 ± 1.4 mg/g methyl orange (MO) dye from 100 mL 25 ppm aqueous dye solutions, thereby increasing the MB and MO absorption amounts of the TH COF structure. Furthermore, by calculating the distribution, selectivity, and relative selectivity coefficients, the absorption capacity order was determined as dp-TH > TH > p-TH COFs for the MB dye, whereas it was p-TH > TH > dp-TH COFs for the MO dye. Finally, the reusability of dp-TH COF for MB absorption and p-TH COF for MO absorption were investigated. After five repeated uses, dp-TH COF retained 64.6 ± 3.7% of its absorption ability, whereas p-TH COF preserved 79.7 ± 3.2% of its absorption ability relative to the initial absorption amount.

Synthesis and spectral properties of H acid-containing dyes and their Mannich-type dyeing performances on silk fibroin

The colouration of silk fibroin through a Mannich-type reaction with aromatic primary amine-containing dyes (APADs), named Mannich-type dyeing, is a novel dyeing method with the advantages of moderate conditions, high selectivity, and high wet fastness. In this study, three novel APADs, including an H acid structure, D1-D3, were designed and synthesized. A similar dye, C1, without an aromatic primary amine group, was selected as the control. Their spectral and colour fastness properties in aqueous solutions and on silk fabrics were measured and evaluated. In addition, their Mannich-type reactivity to silk fabric was evaluated via experiments and simulated calculations. It was revealed that for the H acid-containing dye with the same chromosome structure, the electron accepting/donating properties of the diazo and coupling components affect the colour of the dye after the Mannich-type dyeing. The substituent effect of dyes C1–D3 demonstrated that with the changing properties of electron donation and acceptance in the case of the diazonium component, the absorption spectrum (λmax) of the neutral aqueous dye solution changed from reddish-orange (505 nm) to bluish-violet (541 nm). The λmax of Mannich-type dyed fabrics was generally red-shifted in comparison with that of dyed fabrics by acidic dyeing, which implied the formation of a reactive bond between the dye and the silk fibroin. The presence of aromatic primary amine groups in dyes is the prerequisite for Mannich-type reactivity. The primary amine groups on both benzene and naphthalene rings have Mannich-type reactivity, which is related to the electron cloud density of amino N atoms. With the increase in electron cloud density of the amino N atom, the colour fixation of the dye and the fibre was improved. After the Mannich-type dyeing, the colour fastness of the dyed fabrics and DMF stripping resistance significantly improved, also indicating the formation of a covalent bond between the dye and the fibre. The simulated calculation predicted the colour of APAD in an aqueous solution and on dyed silk fabric after Mannich-type dyeing, which guides the design and enrichment of APADs’ chromatography.