Crystal Violet Dye Research Articles

Investigating the Influence of CuS Ratio on Sun light – driven Photocatalytic Performance of ZnS:CuS Nanocomposites and reusability of PVA/ZnS: CuS polymer membrane

In this study, ZnS and CuS nanocomposites (NCs) were synthesized using a simple and cost-effective co-precipitation method. These NCs were evaluated for their photocatalytic activity in degrading Crystal Violet dye under sunlight. ZnS:CuS nanocomposites were created using QDs in ratios of 4:1, 1:1, and 1:4. The synthesized NCs were analyzed for structural, morphological, chemical purity, and optical properties using XRD, TEM, EDAX, and UV-Vis spectroscopy. Structural analysis revealed phase-pure cubic and hexagonal structures for ZnS and CuS nanoparticles, respectively. The average crystallite sizes of the pure ZnS and CuS and their composites (4:1, 1:1 and 1:4) ratios are 1.66, 14.7, 1.90, 11.2 and 12.1 nm, respectively. TEM analysis confirmed aggregated and isolated particles, matching the SAED pattern and d-spacing values from XRD analysis. Increasing the CuS ratio in the composites enhanced absorption due to a bandgap reduction from 3.99 eV to 3.35 eV. The pure ZnS and CuS NPs and their composites in ratios of 4:1, 1:1, and 1:4 exhibited degradation efficiency of approximately 89%, 87%, 99%, 97%, and 96% respectively over a period of 180 minutes. ZnS:CuS (4:1) exhibited outstanding photocatalytic activity, achieving 90% degradation in 80 minutes under sunlight. Detailed discussions included the proposed photocatalytic mechanism, scavenging activity, and dosage effect. Hemolytic activity assays indicated that the synthesized NCs are nonhemolytic. The PVA and PVA/ZnS:CuS (4:1) composite membrane exhibited degradation efficiency of 63 % and 92 % respectively. ZnS:CuS (4:1) NCs, with their superior capacity for wastewater treatment, were incorporated into a PVA polymer membrane to enhance reusability and prevent photo-corrosion.

Modification of nickel ferrite nanoparticles by sodium docusate surfactant for superior crystal violet dye removal from aqueous solutions.

In this study, nickel ferrite (NiFe2O4) nanoparticles were synthesized using the Pechini sol-gel method and modified with sodium docusate surfactant. The modified nanoparticles showed an enhanced adsorption capacity of 384.62mg/g for crystal violet dye, compared to 237.53mg/g for unmodified NiFe2O4. Characterization was performed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM) techniques. The adsorption process was spontaneous, exothermic, and followed the Langmuir isotherm and pseudo-second-order kinetic model. Optimal conditions for maximum dye removal were achieved at pH 10, 50min, and 298K. Additionally, the synthesized adsorbents demonstrated excellent regeneration and reusability over five adsorption-desorption cycles with minimal efficiency loss.

Fabrication of Multifunctional Green-Synthesized Copper Oxide Nanoparticles Using Rumex vesicarius L. Leaves for Enhanced Photocatalytic and Biomedical Applications

Recently, the use of plant extracts has emerged as an innovative approach for the production of various nanoparticles. Enhancing green methods for synthesizing copper oxide (CuO) nanoparticles (NPs) is a key focus in the field of nanotechnology. This study presents a novel and eco-friendly synthesis of CuO NPs using Rumex vesicarius L. leaf extracts, offering a cost-effective and efficient method. The synthesized CuO NPs were evaluated for their cytotoxic effects against human cervical carcinoma (HeLa) cells, as well as their photocatalytic and antimicrobial activities. The morphology, size, and structural properties of the CuO NPs were characterized using various analytical techniques. X-ray diffraction (XRD) analysis confirmed the pure crystalline structure of the CuO NPs with a size of 19 nm, while transmission electron microscopy (TEM) showed particle sizes ranging from 5 to 200 nm. The photocatalytic performance of the CuO NPs was assessed through the photodegradation of crystal violet (CV) and methylene blue (MB) dyes under UV light. The NPs exhibited excellent decolorization efficiency, effectively degrading dyes in aqueous solutions under irradiation. Furthermore, the green-synthesized CuO NPs displayed strong antibacterial and antifungal activities against a variety of human pathogens. They also demonstrated significant dose-dependent cytotoxicity against the HeLa cancer cell line, with an IC50 value of 8 ± 0.54 μg/mL.

Preparation of New Carbonaceous Adsorbents Based on Agricultural Waste and Its Application to the Elimination of Crystal Violet Dye from Water Media

Preparation of New Carbonaceous Adsorbents Based on Agricultural Waste and Its Application to the Elimination of Crystal Violet Dye from Water Media

Development of an eco-friendly geopolymer mortar using slag and fly ash with high bentonite content for thermal and environmental applications

The construction industry is exploring the use of low-cost waste materials to create eco-friendly geopolymer mortar binders. Our study aims to develop various environmentally friendly geopolymer mortar mixes for thermal and adsorption applications using natural materials like bentonite and industrial by-products such as ground-granulated blast furnace slag and fly ash. Ternary geopolymer mortar pastes are prepared using equimolar amounts of slag (GBFS) and fly ash (FA), with 6%, 8%, 10%, and 12% weight of bentonite (BC) from the total geopolymer weight to study the bentonite replacement effect. The prepared mortar are tested for their physico-chemical, mechanical, adsorption, and thermal stability properties (300 °C to 900 °C). The adsorption behavior of eco-friendly geopolymer mortar mixes against crystal violet dye in aqueous solutions is also identified. The study found that adding 6% bentonite to the slag/fly ash-based geopolymer mortar mix yielded the highest mechanical characteristics. Moreover, all the ternary geopolymer mortar mixes exhibited excellent thermal stability up to 900 °C. In adsorption study, the results indicated that the mortar mixes had excellent capacities and adhered well to the Freundlich isotherm model, suggesting potential applications in treating wastewater. Using bentonite in slag/fly ash geopolymer mortar offers a sustainable, cost-effective, and heat-resistant alternative to traditional cement binders.

Fabrication and adsorption characteristics of cuprammonium cellulose-based membranes for removing anionic and cationic dyes

A cotton linter-based source was used to form conjugate electrospun membranes composed of cuprammonium cellulose, polyethylene oxide, and polyacrylonitrile for the removal of the anionic and cationic dyes from aqueous media. The highest removal efficiencies of 94 %, 89.9 %, 87.4 % were achieved for the anionic dyes Congo red (CR), Metanil yellow (MY), and Methyl orange (MO), respectively, and less so on the cationic dyes Crystal violet (CV), and Rhodamine B (RB) were 55.8 % and 15.1 %, respectively. The pseudo-second-order model effectively described the adsorption kinetics for both types of dyes. The composite membrane exhibited adsorption behaviors following the Dubinin-Radushkevich (D-R) isothermal model. Thermodynamics study suggests that the adsorption process was spontaneous except for the RB dye. The activation energy values of CR, MY, MO, CV, and RB dyes were 27.65, 21.17, 11.50, 10.47, and 71.12 kJ/mol, respectively, confirming the physisorption phenomenon for CR, MY, MO, and CV dyes, while chemisorption occurs for RB dyes. This study investigates the potential of a conjugate electrospun membranes as a reusable adsorbent for dye removal. The effects of solution pH, temperature, and dye concentration on adsorption performance were systematically evaluated. The conjugate electrospun membrane efficiency declined by only 10 % after undergoing five adsorption/desorption cycles.

Enhanced cationic/anionic dyes removal in wastewater by green nanocomposites synthesized from acid-modified biomass and CuFe2O4 nanoparticles: Mechanism, Taguchi optimization and toxicity evaluation

This article addresses the nanoadsorption mechanisms of rhodamine B (RB), crystal violet (CV), and Congo red (CR) using acid-treated C.edulis (ATCE)/CuFe2O4 (ATCE@CuFe2O4) from an aqueous solution. The physical and chemical characterizations of nanobiomass were studied using different techniques. The specific surface areas of the ATCE and ATCE@CuFe2O4 composites were 15.88 and 337.81 m2/g, respectively, indicating a significant specific surface area of ​​the ATCE@CuFe2O4 nanocomposite. A number of functional groups were determined, which promote the binding of the dye to the adsorbent. The SEM also shows that the adsorbent has a homogeneous texture with deep voids and significant porosity, which likely explains the retention and binding of dye ions on the surface of the adsorbent. In fact, the Langmuir isotherm with a correlation coefficient of 99 % for CV, RB and CR, respectively, represents the most suitable model to explain the adsorption mechanism. The maximum adsorption amount is 666.6 mg/g for CV, 645.16 mg/g for RB and 434.71 mg/g for CR at 308 °K. The adsorption kinetic processes were predicted by the pseudo-second order kinetic model. The thermodynamic properties showed that the adsorption on ATCE@CuFe2O4 was possible and spontaneous. The ATCE@CuFe2O4 recycling and elimination CV, RB, and CR were 74.23 %, 72.75 %, and 67.84 %, respectively, after seven cycles. The design, modeling and optimization of the adsorption parameters were carried out using the Taguchi experimental design. The maximum removal efficiency of CV, RB and CR dyes in optimal operating conditions were 99.96, 98.29 and 97.76 %, respectively. Which at the optimal conditions of 1 g/L, 90 min, 20 mg/L, 298 °K, pH 10 for CV and RB dyes and 1 g/L, 90 min, 20 mg/L, 308 °K, pH 4 for CR. This research demonstrated the performance of ATCE@CuFe2O4 in bean seed germination test and its effectiveness in removing dyes from wastewater.

Phenazinium- and Malachite Green-Based Pd(II) Cages: Chiroptical Discrimination of Nucleoside Triphosphates.

Organic chromophores have been successfully implemented into supramolecular systems to bestow them with distinct photophysical properties for various applications, ranging from solar energy conversion, photochemical reactions or as receptors for guest molecules with optical readout. We had previously introduced first members of the large family of coal-tar dyes (methylene blue, crystal violet and rhodamine) as integral components of coordination cages. Here, we add two new chromophores, malachite green (MGP) and a purple phenazinium dye (PHP), serving as backbones of bis-monodentate banana-shaped ligands with pyridine donors. We show the formation of corresponding green and purple coloured Pd2L4 coordination cages and investigate their interaction with chiral guest molecules via UV-Vis and CD spectroscopy. The PHP cage can be used to recognize nucleoside triphosphates, based on chirality transfer from the guests to the structurally flexible helicate. In combination with the already known methylene blue cage MBP we could further differentiate between all four canonical NTPs through characteristic changes in the observed CD signatures.

Two-Dimensional MXene Flakes with Large Second Harmonic Generation and Unique Surface Responses.

MXenes are a family of two-dimensional (2D) materials with broad and varied applications in biology, materials science, photonics, and environmental remediation owing to their layered structure and high surface area-to-volume ratio. MXenes have exhibited significant nonlinear optical characteristics, which have been primarily explored in the context of photonics applications, yet the second-harmonic generation (SHG) behavior of MXenes remains an unexplored aspect of their optical properties. Herein, we demonstrate and quantify large second-order responses of 2D Ti3C2Tx MXenes both in aqueous solutions and on a silicon substrate for the first time. MXene flakes showed strong second-harmonic scattering (SHS) in a dilute suspension with a sensitivity of less than 0.1 μg/mL. Angle-dependent SHS experiments further found that the second-order responses originate from coherent 2D dipole radiation. Through confocal and atomic force microscopies, we found that the intense SHG signal from free-standing MXene flakes increases exponentially with decreasing thickness, while two-photon fluorescence increases linearly with thickness. The second-order susceptibility of the MXenes was determined to be 3.6 pm V-1 with a thickness of 10 nm, almost twice of that for an often-used SHG crystal, beta barium borate. We further explored surface properties of the MXene sheets by investigating the SHS responses upon addition of organic dye molecules to the system. It was found that the adsorption of crystal violet (CV) obeys a Langmuir adsorption model while the addition of malachite green (MG) resulted in almost no change in SHG intensity, even though the adsorption capacities for both CV (61.3 ± 1.7 mg/g) and MG (54.8 ± 2.8 mg/g) are similar. Such a stark difference in adsorption characteristics between cationic organic CV and MG dyes is likely due to their distinct orientational orderings on the MXene surfaces. This work opens many possibilities for the further employment of the family of 2D materials in photonics, optics, and surface catalysis applications.

Nanobioengineered Al2O3 Core-Shell Nanoparticle Preparation Using Bauhinia Variegate Plant Extract for Efficient Photocatalysis and Electrochemical Sensing.

Core-shell-based nanomaterials have garnered considerable attention in the recent past not only in catalytic applications but also in their potentiality in selective and efficient sensing. Present research reports the first and successful biosynthesis of the core (c-Al2O3)-shell nanoparticles (NPs) using Bauhinia variegate blossom extract as reducing and capping agents. The synthesized c-Al2O3 NPs were characterized and utilized to fabricate nanobioengineered electrodes on indium tin oxide (ITO) substrates via electrophoretic deposition. Electrochemical analysis, including cyclic voltammetry and differential pulse voltammetry, revealed quasi-reversible processes with high electron-transfer rates (Ks = 0.66 s-1) and a diffusion coefficient (D = 5.84 × 10-2 cm2 s-1). The electrode exhibited a very high sensitivity (23.44 μA μM-1 cm-2) and a low detection limit (0.463 μM) for sodium azide (NaN3) over two linear ranges of 1-6 and 8-20 μM. Additionally, c-Al2O3 NPs demonstrated the effective photocatalytic degradation of crystal violet dye under visible light, following pseudo-first-order kinetics. The fabricated electrode showed excellent selectivity, stability, and reproducibility, highlighting its potential for environmental monitoring and clinical diagnostics.

Solvothermal synthesis, photoelectricity and photocatalysis of biselenide-containing selenidostannate hybrid with one-dimensional structure

A biselenide-containing selenidostannate hybrid with narrow band gap, [Ni(terpy)2]2[Sn3Se7][Sn3Se6(Se2)]·4H2O (1) (terpy = 2,2′:6′,2′’-terpyridine), was prepared using a Ni(II)-terpy complex cation as the template under solvothermal conditions. In 1, two SnSe5 PBUs and one SnSe4 PBU are joined through edge-sharing to form a Sn3Se9 SBU. The Sn3Se9 SBUs are connected into a 1-D [Sn3Se7]n2n− chain by sharing two Se atoms, while the Sn3Se7(Se2)2 SBUs are interlinked via the same conncetion mode to form a [Sn3Se6(Se2)]n2n− polyselenide chains containing biselenide ligands. Compound 1 exhibited sensitive photocurrent responses under Xe light irradiation, and had a steady current density of 6.88 μA·cm−2 under visible light irradiation at power of 150 W. Compound was photocatalytically active in the degradation of the organic dye crystal violet (CV) in aqueous solution at room temperature, and the degradation ratio of CV reached 93.8 % after 60 min of light irradiation. Radical quenching experiments showed that all the ∙O2− and ·OH radicals, and the photogenerated positive holes h+ were involved in the photodegradation of CV.

Kinetic adsorption studies of methylene blue and crystal violet dyes removal in single and competitive systems using lemon peels/activated carbon/alginate composite

Kinetic adsorption studies of methylene blue and crystal violet dyes removal in single and competitive systems using lemon peels/activated carbon/alginate composite

Pea Pod–Derived Biochar–Zeolitic Imidazolate Framework Composite for the Photocatalytic Degradation of Two Organic Dyes Crystal Violet and Victoria Blue

ABSTRACTThe rapid increase of water pollution globally is a vital environmental concern that requires the immediate attention of researchers to find new innovative ways to remove unwanted environmental pollutants from our water sources. With the advances in the field of sustainable engineering, there is a high demand for the effective utilization of biomass resources for the removal of aqueous environmental contaminants. Biochar is carbon carbon‐enriched substance obtained by biomass pyrolysis; it is inexpensive and has received wide attention in the field of wastewater treatment. Herein, we describe the synthesis of pea pod (PO) biochar‐reinforced zeolitic imidazolate framework (ZIF‐8) nanocomposite (PO@ZIF‐8) through the in situ precipitation of ZIF‐8 onto the biochar surface. The crystal growth, morphology, chemical composition, and optical characteristics of fabricated PO@ZIF‐8 nanocomposite were scrutinized through PXRD, SEM, TEM, UV‐DRS, PL, and XPS analysis. The dodecahedral‐shaped PO@ZIF‐8 particles have an average size between 140 and 160 nm. The biochar‐reinforced ZIF‐8 nanocomposite showed significantly higher photocatalytic activity than the pure ZIF‐8 for the degradation of two commonly found organic dyes crystal violet (CV) and Victoria Blue (VB) in the presence of direct sunlight irradiation. The PO@ZIF‐8 nanocomposite showed the highest degradation efficiency of ~87% and ~80% within 50 min of irradiation time at a catalyst dosage of 20 mg for 30 ppm CV and VB dye solutions at pH 8. First‐order kinetics were obeyed during the photodegradation with 0.041 and 0.030 min−1 as the constant of degradation for the removal of CV and VB. The radical scavenger experiment and the photoluminescence analysis confirm the active participation of ·OH radical in the degradation of both dyes. LC–MS and TOC analysis was also performed to determine the degradation products and for evaluation of the degradation progress. Moreover, the synthesized PO@ZIF‐8 composite also exhibit good stability till the fourth cycle with high degradation efficiency thus making it a good choice of catalyst in the field of environmental decontamination.

Insights into the photocatalytic process of surface-platinized hierarchical anatase TiO2 nanoparticles by in-situ DRIFT analysis

BackgroundEnvironmental remediation researchers are challenged to unravel the mechanisms of dual-responsive photocatalysts for degrading pollutants in both liquid and gas phases. This study aims to provide comprehensive insights into the photocatalytic processes employed by surface-platinized hierarchical anatase TiO2 nanoparticles. The investigation includes an in-depth analysis of the associated mechanism through in-situ DRIFT analysis. MethodsUtilizing surfactant-assisted surface platinized TiO2 samples synthesized through soft-template and chemical reduction techniques, this study investigated their efficacy in the degradation of crystal violet dye (10 ppm) under irradiation from a 380.8 W mercury-xenon lamp. The photooxidation of gas-phase ethanol was subsequently examined using the DRIFT technique. Significant findingsThe Pt-deposited C-TiO2 nanoparticles exhibited an impressive photocatalytic dye degradation efficiency of 87.07 %, surpassing the performance of other synthesized catalysts. To elucidate the mechanism behind this enhancement, an in-situ DRIFT analysis was conducted using the photo-oxidation of ethanol. The enhanced efficiency can be attributed to the incorporation of Pt metal, which serves as an electron collector in the n-type TiO2 semiconductor, thereby prolonging electron lifetime. Additionally, the pivotal role of hydroxyl radicals and holes in generating intermediates was thoroughly examined through DRIFT analysis, providing comprehensive insights into the photocatalytic reaction and the reactive intermediate species involved.

Antibiofilm activities of lactoferricin-related Trp- and Arg-rich antimicrobial hexapeptides against pathogenic Staphylococcus aureus and Pseudomonas aeruginosa strains.

Recently, several antimicrobial peptides (AMPs) varying in length from 12 to 37 residues, have been shown to act as antibiofilm agents. Here we report a study of twenty-three hexapeptides modeled after four different Trp- and Arg-rich AMPs, including the RRWQWR-NH2 peptide, derived from bovine lactoferrin. They were tested against the pathogenic Gram-negative Pseudomonas aeruginosa PAO1 strain and a Gram-positive Staphylococcus aureus MRSA strain. Both strains were engineered to express the GFP protein, and fluorescence detection was used to measure the ability of the peptides to prevent biofilm formation (MBIC) or to cause the breakdown of established biofilms (MBEC). Similar antibiofilm activities were obtained with the standard crystal violet dye assay. Most Trp- and Arg-rich hexapeptides displayed a potent antibiofilm activity against the Gram-positive S. aureus MRSA strain. In particular, hexapeptides with 3 Arg and 3 Trp were very effective, especially when they contained the three Trp in sequence. Somewhat unexpectedly, the antimicrobial (MIC) values correlated with the MBIC and MBEC values, which has not been seen for some other AMP/antibiofilm peptides. Our results demonstrate that short Trp- and Arg-rich peptides merit further studies as antibiofilm agents, that could be deployed to address part of the antimicrobial resistance problem.

Synthesis, Characterization, Biological Potency, and Molecular Docking of Co2+, Ni2+, and Pd2+ Complexes Derived From Carbohydrazone Ligand and Its Application in Dye Removal

ABSTRACTAs a result of the Schiff base condensation reaction between carbohydrazide and 4‐aminoacetophenone, novel HL ligand [(Z)‐N′‐((Z)‐1‐(4‐aminophenyl)ethylidene)‐2‐(1‐(4‐aminophenyl)ethylidene)hydrazine‐1‐carbohydrazide] and three coordination compounds were successfully obtained with the formulas of [Co2(L)(Cl)3(H2O)].Cl, [Ni2(L)(Cl)2(H2O)2].Cl.H2O, and [Pd (HL)(Cl)(H2O)].Cl, the obtained structures were analyzed using analytical and spectroscopic techniques such as Fourier‐transform infrared (FT‐IR), NMR, UV–Vis, molar conductivity, elemental analysis, and magnetic susceptibility measurements. Additionally, thermal stabilities, kinetic, and thermodynamic parameters were estimated utilizing thermogravimetric analysis. The structures were confirmed through quantum chemical computations. The antioxidant, anticancer, and antimicrobial biological efficacies of the ligand and its metal chelates were assessed. The ligand shows optimistic results as an antioxidant, while Co2+ and Pd2+ complexes showed the highest antimicrobial activities. The DNA binding affinity and cleavage of the isolated compounds were evaluated. Furthermore, the fluorescence spectrum of ligand in the absence and presence of Co2+ was recorded in order to investigate the interaction affinity along with the limit of detection. Another application of this work is the removal of methylene blue and crystal violet dyes from wastewater and reusability, through an inventive synthesis of a cellulose‐based material “LDC” Schiff base.

Green synthesis of Z-scheme CeO2 decorated ZnO nanocomposites for photodegradation of organic pollutants, antioxidant activity and its effects on seed germination

The present work aimed to report a green synthesis of CeO2@ZnO nanocomposites via co-precipitation method using azadirachta indica aqueous leaf extract. The characterization of the prepared CeO2@ZnO nanocomposites were done using XRD, FTIR, SEM, EDAX, UV–vis, and PL techniques to examine the structural properties, functional group, morphological and electronic properties. As prepared CeO2@ZnO nanocomposites have been used for photo degradation of Crystal Violet (CV), Methylene blue (MB) and Rhodamine B (RhB) dyes in presence of solar light in aqueous solution. From structural analysis the mean crystallite sizes of the synthesized nanocomposites varied from 27 nm to 9 nm. The degradation of MB, CV and RhB dyes follows pseudo-first order reaction rate with the rate constants k1 for MB is 10.09 × 10−3 min−1, k1 for CV is 8.71 × 10−3 min−1, k1 for RhB is 0.92 × 10−3 min−1.The characterized nanocomposites were used for seedling growth, physiological and biochemical responses during seed germination. In CeO2@ZnO nanocomposites treatments, significantly higher values of shoot length and root length were observed in CZ1 (0.5, and 1 mg/ml) treated seedlings as compared to other samples. Similarly, the activities of ɑ-amylase and protease enzymes were recorded to be maximum for CZ1 nanocomposites. For instance, the increased activity of α-amylase was observed to be 2.12, 2.09, and 1.33 folds higher in CZ1, CZ2, and CZ3 (1 mg/ml) treated seedlings as compared to the control. Similarly, the protease activity was reported to be increased by 0.011 folds in CZ1 nanocomposites (1 mg/ml) treated seedlings as compared to the control. Furthermore, all the CeO2@ZnO nanocomposites have excellent DPPH, and ABTS free radical scavenging activities, confirmed by the Ferric-Reducing Antioxidant Power (FRAP) assay. The CZ1 nanocomposites showed the best results. The CeO2@ZnO nanocomposites were found to have no toxic effects on cellular division confirmed with improved mitotic index under different treatment regimens.

Structural and morphological studies of g-C3N4-functionalized MWCNTs nanocomposite for sunlight-responsive photocatalytic activity

Photocatalytic degradation of organic contaminants has been proven to be one of the greatest economical and efficient techniques to address environmental pollution problems. Multi-walled carbon nanotubes (MWCNTs)/g-C3N4 (GCN) nanocomposites (NCs) were synthesized by a hydrothermal process aided by ultrasound to produce active photocatalysts. The effective synthesis of GCN, MWCNTs, and MWCNTs/GCN NCs was confirmed by X-ray diffraction (XRD) patterns. The fabrication of GCN nanosheets (NSs), the nanotubular structure of MWCNTs, and a network of neuron-like structures for MWCNTs/GCN NCs were all revealed by structural and morphological characterization. The elemental mapping of NCs containing the suitable quantity of MWCNTs revealed a uniform distribution of the sample's component elements. When the optical properties of the fabricated nanomaterials were examined by employing UV–visible spectroscopy, the results revealed a blue shift (a shift of maximum absorption to the UV region), which suggests that the addition of MWCNTs increased the band-gap energy. The behaviour of e––h+ pair recombination was revealed by measuring the charge carrier movement and trapping efficiency using photoluminescence (PL) spectroscopy. Crystal violet (CV) dye was photocatalytically degraded using prepared NCs in the presence of sunlight, and the synergistic effects of GCN and MWCNTs were examined. With a degradation efficiency of 99.32 %, MWCNTs/GCN NCs demonstrated the best sunlight-irradiated photocatalytic activity for CV degradation. The degradation of CV was discovered to follow pseudo-first-order kinetics. Throughout five consecutive studies, the NCs demonstrated the highest levels of catalytic efficiency and recyclability, with 5 % reduced degrading activities. The trapping tests showed that the primary reactive species involved in the breakdown of CV were the •O2– and •OH radicals.

Phyto-mediated synthesis of ZnO nanoparticles and their sunlight-driven photocatalytic degradation of cationic and anionic dyes

Abstract In this study, zinc oxide-based nanocatalysts were biosynthesized using Ocimum basilicum (OB) and Olea africana (OA) leaf aqueous extracts, termed OB-ZnO and OA-ZnO, as a simple, affordable, and environmentally friendly approach. Their characteristics and efficacy in photodegrading cationic dyes (crystal violet and methylene blue) and anionic dyes (methyl orange and naphthol blue black) were investigated. The catalyst’s properties were analyzed using various techniques, including Fourier transform infrared, X-ray diffraction, photoluminescence, thermogravimetric analysis, UV-Vis, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and Brunauer–Emmett–Teller. Analysis revealed pure products having a hexagonal wurtzite structure, crystallite sizes of 15.04 and 21.46 nm, surface areas of 23.65 and 7.97 m2/g, particle sizes of 35 and 170 nm with spherical (uniform) and oval-like (non-uniform) shapes, and optical bandgaps of 3.15 and 3.05 eV, respectively. Photocatalytic applications under sunlight indicated excellent activity of both catalysts against targeted cationic and anionic dyes. Most notably, even though OA-ZnO has a lower surface area than OB-ZnO, it demonstrated greater efficiency. The variation in effectiveness is explained by the lower bandgap value of OA-ZnO and its ability to reduce electron–hole recombination due to its larger crystal size, which accelerates the degradation process. Additionally, both catalysts exhibited high stability after being used four times.

The Dynamic Impact of Synthetic Dyes on the Physicochemical Parameters of Cationic and Anionic Surfactants

Introduction: The interaction of dyes (crystal violet, malachite green, and congo red) with cationic (cetrimide) and anionic surfactants (sodium dodecyl sulfate) in the aqueous medium were studied via conductometric and UV-visible spectroscopy. Method: The critical micelle concentration (CMC) of both cetrimide and SDS upsurges in all the selected dyes on increasing the temperature. Thermodynamic parameters like change in Gibb’s free energy of micellization (Δ G°m ), change in enthalpy of micellization (Δ H°m ) as well as change in entropy of micellization (Δ S°m ) were calculated by employing mass action model. Result: The Δ S°m values obtained are positive with Δ G°m and Δ H°m values being negative signified that the phenomenon of micellization is spontaneous as well as exothermic in nature. Moreover, the more negative Δ H°m in water as well as in the presence of dyes signify the presence of electrostatic forces of attraction between the oppositively charged dyes and surfactant moieties. UV-spectroscopy reveals that spectral changes occur because of the interaction of surfactants with dye molecules. Conclusion: By analyzing shifts in absorption peaks, changes in intensity, and alterations in band shape, insights into the nature of surfactant-dye complexes and their potential applications in various industries can be assessed. This understanding can help in the design and optimization of products and processes involving surfactants and dyes.