Organic Dye Pollutants Research Articles

Birnessite-MnO2 nanostructures synthesized by facile hydrothermal and green method for dye degradation application

Water contamination resulting from the presence of organic dye pollutants in the ecosystem is a significant issue in the 21st century, that requires urgent resolution. Utilizing an effective nanocatalyst for the removal of dyes from water is a viable solution to address this problem. In this study, we proposed two distinct approaches for synthesizing δ-MnO2 nanostructures: an environmentally friendly, “green” method (MG) and a “cost-effective” hydrothermal method (MH). The leaf extract of Clinacanthus nutans was used for the preparation of MG, while MnSO4 was used for MH as a reducing agent, along with KMnO4, with the reaction time fixed at 90 °C. X-ray diffraction analysis confirmed that both approaches yielded δ-MnO2 nanostructures with a monoclinic Birnessite phase. The MG sample displayed a coagulated nanoflake-like morphology, as observed in FESEM images. On the other hand, the MH sample exhibited a distinct nanoflower morphology. The materials' optical properties were investigated using UV–visible spectra analysis, revealing direct bandgap energies of 2.2 eV and 2.58 eV for the MG and MH, respectively. The surface area of the MG sample was found to be higher as compared to the MH nanoflower, showcasing a mesoporous structure. XPS analysis was employed to determine the oxidation states of the elements. The effect of varying pH levels on the degradation of Methyl Orange dye by the two nanocatalysts was investigated. The results demonstrated that acidic pH led to higher decolouration efficiency, particularly notable for the MG nanocatalyst. Consequently, this study illustrates that the green δ-MnO2 nanocatalyst effectively degrades methyl orange dye under acidic conditions through photocatalysis.

Photocatalytic performance of (Zn,Me)–SnO2 nanoparticles (Me= Nb5+ or W6+) under UV light for efficiently degradation of organic dye pollutants

In this study (Zn,Nb)-doped SnO2 and (Zn,W)-doped SnO2 were synthetized using chemical route by calcination at 600 °C/2 h and milling at 500 rpm/1 h to verify its behavior as a photocatalyst. The powders showed high surface area: 57.1 m2/g for (Zn,Nb)-doped SnO2 and 74.3 m2/g for (Zn,W)-doped SnO2, both showed 10–25 nm of average diameter and rutile crystalline phase after morphological and structural characterizations. UV–vis spectroscopy indicated a band gap of 3.53 eV for (Zn,Nb)–SnO2 and 3.35 for (Zn,W)–SnO2. The photocatalytic activity was verified through the decomposition of Rodhamine B (RhB) aqueous solution under ultraviolet light radiation of 9W. After 120 min the efficiency of (Zn,Nb)–SnO2 was 68.5 % and for (Zn,W)–SnO2 was 71.1 %. Using a UV-lamp of 11W the efficiency in photodiscoloration of RhB aqueous solution increased to 83.2 % with (Zn,W)-doped SnO2 powder in a shorter irradiation time (90 min), indicating its potential use as nanostructured photocatalyst ceramic powder.

A facile green synthesis of gold nanoparticles using Canthium parviflorum extract sustainable and energy efficient photocatalytic degradation of organic pollutants for environmental remediation

Organic dye and nitrophenol pollution from textiles and other industries present a substantial risk to people and aquatic life. One of the most essential remediation techniques is photocatalysis, which uses the strength of visible light to decolorize water. The present study reports Canthium Parviflorum (CNP) leaf extract utilization as an effective bio-reductant for green synthesis of Au NPs. A simple, eco-friendly process with low reaction time and temperature was adopted to synthesize CNP extract-mediated Au-NPs (CNP-AuNPs). The prepared AuNPs characterization involving X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron microscopy (XPS) surface area analysis, ultraviolet–visible spectroscopy (UV–Vis). XRD results showed that the cubic-structured AuNPs had a crystallite size of 14.12 nm. Assessment of organic dyes performance in degrading brilliant green (BTG) and amido black 10B (AMB) under visible light irradiation highlights an impressive 83.25% and 86% degradation efficiency within 120 min, accompanied by a kinetic rate constant dyes was found to be 0.0828 min⁻1, BTG, and 0.0123 min⁻1, Furthermore, the reduction of 4-nitrophenol by NaBH4 using CNP-AuNPs as a catalyst demonstrated good catalytic performance and rapid degradation at 89.4%. and rate constant 0.099 min−1 followed pseudo-first-order. The LC-MS analysis identified various intermediates during the degradation of the CR dye. Radical trapping experiments suggest that photogenerated free electrons and hydroxyl radicals are crucial for degrading the amido black 10B dye The AuNPs influenced the significant factors responsible for the photocatalytic activity, such as the increase in range of absorbance, increased e− and h+ pair separation, improvement in the charge transfer process, and active site formation, which significantly enhanced the process of degradation. We found that the CNP-AuNPs could effectively remove dyes and nitrophenol from industrial wastewater.

Green Synthesis, Characterization, and Evaluation of Photocatalytic and Antibacterial Activities of Co3O4-ZnO Nanocomposites Using Calpurnia aurea Leaf Extract.

The green synthesis of transition metal oxide nanocomposites using plant extracts is a new and effective method that avoids the involvement of hazardous chemicals. Nondegradable organic pollutants and antibiotic drug resistance have become serious public health issues worldwide. Hence, the main objective of this study is to synthesize Co3O4-ZnO nanocomposites using Calpurnia aurea leaf extract and evaluate its photocatalytic and antibacterial activities. The green synthesized particles were characterized using UV-vis spectra, Fourier transform infrared spectroscopy, X-ray diffraction techniques, and scanning electron microscopy combined with energy-dispersive X-ray studies. The synthesized particles were found to be crystalline in nature with average crystallite sizes of 23.82, 14.79, 15.99, 16.46, and 21.73 nm. Scanning electron microscopy shows the spherical morphology of Co3O4-ZnO NCs, and energy-dispersive X-ray analysis confirms the formation of highly pure ZnO NPs and Co3O4-ZnO NCs. The photocatalytic activity was performed under natural sunlight using malachite green as an organic dye pollutant. The green synthesized ZnO NPs, Co3O4 NPs, 1:4, 1:3, and 1:2 Co3O4-ZnO NCs showed high degradation efficiency after 60 min of irradiation. The synthetic material showed good potential against Staphylococcus aureus and Escherichia coli, with the highest growth inhibition recorded by 1:2 Co3O4-ZnO NCs. The kinetics study of the photocatalytic degradation was confirmed as pseudo first order, and the possible mechanisms for both photocatalytic and antibacterial activities were clearly determined.

Graphene Oxide as Novel Visible Light Active Photocatalyst: Synthesis, Modification by Nitrogen and Boron Doping, and Photocatalytic Application

Graphene oxide (GO) has become one of the emerging and important sole photocatalyst nanomaterials in recent years due to its exceptional/tunable optoelectronic properties, multifunctionality, and eco‐friendly nature. However, challenges remain in tuning surface chemistry, tailoring the band gap, developing doping strategies, and understanding the sole photocatalytic mechanism. This contribution investigated the synthesis of GO via the improved Hummers method by varying the ratio of the oxidizing agents (K2Cr2O7:KMnO4), as well as modifications by nitrogen (N) and boron (B) doping in view of its applications in photocatalytic degradation of organic dye pollutants. Furthermore, changes in surface chemistry, optical, compositional, morphological, and structural properties are investigated to understand the photocatalytic mechanism. The synthesized GO showed a broad spectrum of light absorption with a tunable band gap of 2.4–4.3 eV and exhibited more than 91% degradation of methylene blue dye under direct sunlight. However, the photocatalytic activity decreased after N and B doping attributed to reduced oxygen‐containing functional groups, low surface area, and dopants‐induced bonding configurations within the GO structure. This study provides a new insight into replacing metallic semiconductor photocatalysts with highly affordable, environmentally friendly, and potent metal‐free GO photocatalysts.

Ultrasound-assisted heterogeneous process for organic dye pollutants destruction using the novel MIL-101(Fe)/ZrO2/MnFe2O4 nanocomposite catalyst from water medium

Ultrasound-assisted heterogeneous process for organic dye pollutants destruction using the novel MIL-101(Fe)/ZrO2/MnFe2O4 nanocomposite catalyst from water medium

Graphene-based photocatalytic membrane application for the remediation of organic dye pollutants: A review

The inadequate elimination of emerging organic contaminants, such as pharmaceuticals and personal care items, presents a substantial risk to water security in treating wastewater and its subsequent discharge into the receiving water bodies or recharging groundwater. A practical solution can be found by combining hybrid photocatalytic oxidation with membrane separation technologies. The review examines the crucial process of strengthening photocatalytic membranes by including graphene and its derivatives. Further, it highlights the graphene's ability to improve anti-fouling properties with increased efficiency of pollutant degradation. An in-depth analysis of the synthesis method and its impact on graphene-based photocatalytic membranes' morphology and photocatalytic characteristics is conducted. In addition to discussing membrane alteration, the review delves into the different elements and complexities involved in optimising filtration performance. Adding a comparison with carbon-based support membranes enhances the overall understating of graphene's importance in the membrane matrix. Economic and life cycle aspects have also been elaborated to gauge the practical viability of these neoteric photoactive membranes. The present article also pinpoints the existing lacuna and lays forward potential solutions that can assist in broader acceptance of these membrane for contaminant remediation. Though the development of graphene-based photocatalytic membranes is still in an embryonic phase, the review advocates it as a sustainable successor to conventional membrane-based treatment in the future.

Novel Biomaterial-Derived Activated Carbon from Lippia Adoensis (Var. Koseret) Leaf for Efficient Organic Pollutant Dye Removal from Water Solution

Today, various pollutants, such as dyes from industries, are being released into the environment worldwide, posing significant challenges that require sustainable attention and advanced solutions. This research focuses on the synthesis and characterization of a novel biomaterial-based activated carbon (AC) derived from Lippia Adoensis (Koseret) leaves and investigates its effectiveness in removing MB from aqueous solutions. The biomaterial adsorbent derived from LA was subjected to proximate analysis, pH-point zero charge (pHpzc), FT-IR, and SEM characterization. The pHpzc results indicated a slightly acidic surface functional group for AC. The impact of temperature and chemical impregnation (H<sub>3</sub>PO<sub>4</sub>, NaCl and NaOH) was examined, with the optimal temperature of AC preparation found to be 600°C. The use of H<sub>3</sub>PO<sub>4</sub> for the chemical activation of biomaterials resulted in a high AC surface area. Batch adsorption experiments involved varying pH (2–10), dosage (0.1–0.35 g/50ml), initial concentration (10–35 ppm) and contact time (15–105 min). The optimal parameters were determined as pH = 8, dose = 0.25g, concentration = 10 ppm, and contact time = 75 min. The maximum adsorption capacity and removal efficiency were calculated as 3.99 and 92.2%, respectively. Thermodynamic analysis confirmed the spontaneous and endothermic nature of the system. Adsorption isotherm and kinetic studies revealed a good fit with the Langmuir isotherm (R<sup>2</sup>= 0.999), indicating monolayer adsorption and the pseudo-second order model, respectively. These findings suggest that the use of LA-AC could offer a cost-effective solution for the removal of methylene blue from water, contributing to the solution of water pollution challenges and promoting the adoption of eco-friendly wastewater treatment technologies.

Wurtzite CdS ratio tunability on α-Fe2O3/CdS synergistic heterostructure for enhanced UV-induced photocatalytic decomposition of rhodamine 6G dye pollutant

Hematite α-Fe2O3 exhibits a slow catalytic reaction rate and low performance in aqueous pollutant decomposition. In this work, α-Fe2O3/CdS binary heterostructure composites were created by introducing different ratios of wurtzite CdS into α-Fe2O3 within 0–100 wt% via precipitation and impregnation methods. The photocatalytic performance of α-Fe2O3/CdS was enhanced for the decomposition of aqueous rhodamine 6G (R6G) dye under ultraviolet (UV) irradiation. SEM images reveal that higher CdS loading results in increased interfacial contact between rod-like CdS and spherical-shaped α-Fe2O3. XRD and FTIR results confirm the coexistence of rhombohedral α-Fe2O3 and hexagonal CdS phases, with peak strength proportional to the ratio of component loading, as the respective elements were verified through EDX analysis. The UV-Vis spectroscopic analysis exhibits an enhancement in optical absorption and band gap broadening as the CdS loading rises. α-Fe2O3/CdS with increased CdS loading exhibits faster and more efficient R6G degradation under UV exposure, as evidenced by greater rate constants and degradation efficiency, with optimal CdS loading of 90 wt% achieving a maximum efficiency of 79.14%. The present heterostructure could be employed in future wastewater remediation for effective removal of organic dye pollutants, further promoting clean water preservation for global environmental sustainability.

BiVO4 photoanode modified with FeOOH cocatalyst for visible-light-driven photoelectrocatalytic degradation of organic pollutants

Photoelectrocatalytic (PEC) could effectively and gently treat wastewater. Nonetheless, catalysts face the pronounced tendency of sluggish photogenerated carrier transfer and carrier recombination. In this paper, we herein fabricate FeOOH/BiVO4 photoanode through the incorporation of a cocatalyst FeOOH onto the BiVO4 surface. This modified photoanode demonstrated improved performance when coupled with peroxomonosulfate (PMS) for the purpose of oxidizing tetracycline hydrochloride (TCH) within the PEC system. In the presence of 0.3 mM PMS, the degradation efficiency of TCH increased from 65 % to 88 % within 60 min. The effects of PMS concentration, applied voltage and TCH concentration on the decomposition were studied in detail. Through free radical scavenging experiments, it was found that SO4•-, h+ and ·OH played an important role in TCH degradation. In addition, the FeOOH/BiVO4 with PMS activation in the PEC system also could be capable of dealing with some more organic pollutants (antibiotics and dyes) and achieving good degradation effect. More importantly, TCH degradation rate by FeOOH/BiVO4 photoanode is still over 80 % after five cycles of reuse. This work provides a promising approach for the synthesis of novel photoanodes in the PEC systems with excellent PEC properties in removing environmental pollutants.

The effective polymeric macromolecule as peroxymonosulfate activator as an alternative to metal oxides in the treatment of organic dye pollutants

Catalyst efficiency is affected by inhomogeneous catalyst atom placement on the substrate, leading to nano-level aggregation and reduced performance. Research on single-atom catalysts aims to place them at the atomic level to maximize efficiency, but faces challenges and high costs. This study presents a cost-effective approach using polymeric phthalocyanine Co(II) complex (poly-CoPc) prepared by a simple method. Poly-CoPc shows superior catalytic activity by acting as a catalyst without requiring additional processing. Co(II) atoms in the polymer matrix are covalently coordinated into single atoms and inhibit nanoparticle growth. The poly-CoPc/PMS system outperforms Co3O4 and unsubstituted cobalt phthalocyanine, achieving 97.06% Rhodamine B degradation in 20 min. Furthermore, the poly-CoPc proves to be the most effective, with a degradation efficiency of 69.94% for tap water and 95.76% for seawater, producing predominantly 1O2. These results position poly-CoPc as a promising PMS activator for environmental treatment that surpasses metal oxide derivatives in terms of activity and properties.

Ultrafast catalytic reduction of organic pollutants using ternary zinc–copper–nickel layered double hydroxide

Water is the utmost essential commodity for the support of life process in animals. In recent decades, rapid industrialization and uncontrolled agricultural practices have led to increased level of toxic pollutants in groundwater, including organic pollutants (dyes, nitroarene compounds, antibiotics, etc.), inorganic pollutants (heavy metals, nanoparticles, etc.), and pesticides, posing a serious threat to human health and the environment. Although various technologies such as adsorption, photocatalysis, reverse osmosis, filtration, sedimentation, flocculation, and precipitation are available for the elimination of toxic pollutants from wastewater, issues such as their cost and efficacy limit their usage. Recently, catalysis has been found to be the most effective approach since it exhibits significant capability to eliminate almost all the pollutants and offers the benefit of simple design and low initial cost. In the present study, ternary zinc–copper–nickel layered double hydroxide (ZnCuNi‐LDH) synthesized using facile acid hydrolysis method was employed as an efficacious heterogeneous catalyst for the reduction of NACs (para‐nitrophenol and para‐nitroaniline) and degradation of organic azo dyes (methyl orange, amaranth, and brilliant black). ZnCuNi‐LDH exhibited superior catalytic activity for the reduction of all five model pollutants with reduction efficiency of more than 95% within a short time span of 5 min. Therefore, keeping in view the layered structure, high specific surface area, and remarkable catalytic performance, ZnCuNi‐LDH holds immense potential for the large‐scale catalytic degradation of refractory pollutants.

Constructed of Cd-based organic framework heterostructure material for solar-powered organic dye purification

A novel water-stable Cd-based organic framework material (Cd-MOF) has been synthesized based on the 4,4′-([2,2′-bipyridine]-6,6′-diylbis(oxy))phthalic acid (H4L) ligand and Cadmium nitrate tetrahydrate (Cd(NO3)2·4H2O) with a solvothermal method. We also prove that the rational design and preparation of Cd-MOF\\Ag heterojunctions by depositing Ag nanoparticles on the surface of Cd-MOF is an effective photocatalyst for the degradation of organic dyes in water. The photodegradation rates of RhB and MO were significantly improved under simulated sunlight conditions (AM1.5G), which reaching 0.68 and 1.549 min−1 g−1, respectively. The prominent performance is attributed to the efficient separation of photo-generated electrons and holes caused by the composite heterojunction of Cd-MOF/Ag. The surface plasmonic resonance (SPR) effect of Ag nanoparticles and the Schottky junction between Ag and Cd-MOF play crucial role in the photocatalytic degradation process. This work provides a new strategy for preparing photocatalysts and promoting the development of the degradation of organic dye pollutants in effluent with MOF-based material as photocatalysts.

A nanocomposite containing orange emissive quantum dots for degradation of fluorescein sodium

Obtaining high-efficiency photocatalytic materials responsive to visible light is crucial to eliminating organic dye pollution in industrial wastewater. The paper describes the optical characteristics of ZnO-decorated visible-light-responsive orange-emitting carbon quantum dots ZnO (ZnO/O-CQDs composites). The composite was tested for its photocatalytic capabilities through the photodegradation of fluorescein sodium, a dye. Despite its vast usage and irritant properties, this is the first report on the photodegradation of fluorescein sodium using a customized ZnO/CQDs photocatalyst. Under visible light, the photocatalytic degradation efficiency reached 96.3 % over just 40 min. We also investigated the structural and elemental composition of the ZnO/O-CQDs using TEM, FESEM, EDS, and XPS. The results confirm that O-CQDs with varying properties promote ZnO's photocatalytic activity. The degradation obeyed the pseudo-first-order kinetics model with a photocatalytic rate constant (k) of 0.082 min−1, significantly higher than that of pure ZnO (0.048 min−1).

Revolutionizing dye removal: g-C3N4-Modified ZnO nanocomposite for exceptional adsorption of basic fuchsin dye

Organic dye pollution poses a critical environmental challenge, necessitating sustainable solutions for effective removal. This study presents a g-C3N4-modified ZnO nanosorbent to remove Basic Fuchsin dye from aqueous solutions efficiently. Synthesis and comprehensive characterization (SEM, BET, XPS, FTIR, XRD) elucidated the nanosorbent's properties and adsorption performance and mechanisms. Experimental results demonstrate optimal performance under alkaline conditions, with significant adsorption capacity (up to 478.14 mg/g at 300 ppm dye concentration). Adsorption behavior is well-described by the Freundlich isotherm and pseudo-first-order kinetic models. The nanosorbent demonstrates reusability and cost-effectiveness and exploits hydrogen bonding and π-π interactions for adsorption. This work highlights the potential of g-C3N4@ZnO as a promising solution for mitigating dye pollution and promoting sustainable water treatment technologies.

S-Schematic CuWO4/ZnO nanocomposite boosted photocatalytic degradation of organic dye pollutants

S-schematic CuWO4/ZnO nanocomposite photocatalyst was synthesized by an impregnation method. Synthesized CuWO4 and ZnO nanoparticles, and CuWO4/ZnO nanocomposites were thoroughly characterized. X-ray diffraction (XRD) analysis of the CuWO4/ZnO nanocomposite confirmed the respective triclinic and hexagonal wurtzite structures of CuWO4 and ZnO crystals. Raman and Fourier transform infrared (FTIR) spectra and X-ray photoelectron spectroscopy (XPS) revealed bond formations in CuWO4 and ZnO, and confirmed the synthesis of the CuWO4/ZnO nanocomposite. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed CuWO4 nanoparticles adhered to ZnO aggregates. Energy dispersive X-ray spectrometry (EDS) confirmed the distribution of CuWO4 on the ZnO aggregates. UV–Vis diffuse reflectance spectroscopy (DRS) showed optical bandgap energies of 2.36 eV for CuWO4 and 3.18 eV for ZnO nanoparticles. The photocatalytic performance of the CuWO4/ZnO nanocomposite was investigated through the degradation of the cationic dyes methylene blue (MB) and Rhodamine B (RhB) and the anionic dye methyl orange (MO). A 5.0%CuWO4/ZnO nanocomposite degraded 100% of MB within 120 min, 91.02% of RhB within 300 min, and 89.13% of MO within 300 min. The pseudo-first order kinetic rate constant fit well for the degradation of all the dyes on the CuWO4/ZnO nanocomposite. The CuWO4/ZnO nanocomposite could better degrade the cationic dyes than the anionic dye in an aqueous solution. The hole (h+), the hydroxyl radical (•OH), and the superoxide ion (•O2−) were the active species responsible for degrading MB, RhB and MO dyes. The proposed CuWO4/ZnO nanocomposite could be applied for environment friendly wastewater treatment.

In-silico and in-vitro targeting of organic dye pollutants from synthetic and real wastewater by the hierarchically self-assembled laccase@bismuth phosphate hybrid nanorods

The increasing presence of dyes in wastewater and even surface or groundwater has progressively become an emerging global concern. This study evaluated the potential use of facile, straightforward, and hierarchical laccase@BiPO4•hybrid nanostructures (HNSs) in the elimination of anthraquinone, monoazo, diazo, and triarylmethane dyes from municipal wastewater through in-silico and in-vitro analyses. The prepared HNSs possessed rod-like morphological features with more than 8 cycles of reusability and about 10 U mg–1 catalytic activity. The nitrogen sorption analysis revealed that the prepared HNRs presented a Brunauer-Emmett-Teller (BET) surface area of 15.3 ± 1.6 m2 g−1 and an average pore size of 9.7 ± 0.5 nm. The total pore volume of HNRs was also measured at 4.0 ± 0.1 (× 10−2 cm3 g−1). Molecular docking predicted the preferred orientation of dye molecules with the enzyme's active site, facilitating the formation of stable complexes. The constructed hybrid nanorods (HNRs) showed proper in-vitro oxidation activity on the pollutant dyes with a more than 95% bioremoval for Direct Blue-15, Direct Blue-71, Crystal Violet, and Acid Blue-92. The maximum adsorption capacity of the prepared HNRs was 401 ± 11 mg per g of the carrier after 240 min of contact time with initial dyes' concentrations. Freundlich isotherm well fitted on the removal data compared with the Langmuir model due to the formation of a uniform monolayer of the dyes onto the prepared HNRs. For Direct Blue-15, Direct Blue-71, Crystal Violet, Acid Blue-92, and Acid Red-18, R2 values of pseudo-second-order kinetic were closer to 1 than that of first-order. The thermodynamic evaluations indicated that the removal of the dyes by the immobilized enzyme proceeded spontaneously and favorably (0 > ΔG°), albeit with endothermic characteristics (0 < ΔH°). Bioremoval efficiencies of 32%, 51%, 64%, and 72% were recorded when actual wastewater samples underwent treatment with 0.3 U mL−1, 0.6 U mL−1, 0.9 U mL−1and 1.2 ≤ U mL−1 of HNPs, respectively. Furthermore, the enzymatic removal process led to less toxic metabolites as confirmed using the bacterial growth inhibition test. Therefore, laccase@BiPO4•HNRs can be a worthy approach in dye removal from wastewater due to their distinct physicochemical and catalytic properties.

Syzygium cumini-mediated synthesis of rGO/Ag-Au nanostructures: Efficient catalysts for rapid degradation of organic dyes

BackgroundThe increasing human health risk caused by contamination of water by both natural and synthetic dye pollutants has become a crucial issue and poses an immense urge to find a sustainable approach for the removal of dye contaminants from wastewater. Photocatalysis performed in the presence of nanomaterials holds huge promise as an efficient and environmentally safe oxidation technology for organic dye removal from waste water. MethodsOur preparation methodology utilizes the extract derived from the endocarp of Syzygium cumini (SC) effects for concurrent reduction of GO and metal ions to form rGO/Ag-Au. The prepared rGO/Ag-Au nanostructures effectively breakdown organic dye pollutants like methylene blue (MB) and methyl orange (MO) dyes. Significant findingsA robust interaction between the rGO matrix and the Ag-Au nanoparticles was established by structural characterization, while morphological investigation displayed the nanoscale Ag-Au particles uniformly coated over the rGO sheet surface. The catalytic efficiency of the rGO/Ag-Au nanocomposite toward methylene blue (MB) and methyl orange (MO) chromophores decomposition was assessed with the aid of sodium borohydride (NaBH4). The decoration of well-spaced Ag-Au nanoparticles over the rGO sheet created firm catalytic active sites in the rGO/Ag-Au composite. With the improved catalytic active surface, the MB/MO dye was completely removed in a very short time of 2.5 to 5 min. The rGO/Ag-Au composite exhibited exceptional catalytic prowess in the disintegration of both dyes, leading to complete degradation. The remarkable efficacy in the dye degradation process can be attributed to the predominance of both electrostatic as well as π-π interactions between the nanocomposite and the dyes. As a result, the current study has developed an easy-to-use and green method for creating rGO/Ag-Au composites, offering a workable way to dispose of hazardous organic dyes in an affordable and efficient way.

Synthesis of highly efficient ternary phase graphene/Bi/SnO2 photocatalyst for degradation of organic dye pollutants

In this work, graphene nanosheets (GNs) are prepared from graphite rods obtained from waste dry-cell batteries using the electrochemical exfoliation (ECE) method. Then GNs used as a matrix to modify tin oxide (SnO2) and Bismuth (Bi) nanoparticles to prepare a binary phase SnO2@G and ternary-phase Bi@SnO2@G nanocomposite materials by wet-chemical method and used as a photocatalysts for degradation of organic dye pollutants. XRD diffraction pattern clearly confirmed the presence of tetragonal crystal system of SnO2 which was maintaining its structure in SnO2@G and G/Bi/SnO2. The stretching and bending vibrations of the functional groups were analyzed using FTIR analysis. FESEM images demonstrated the surface morphology and the texture of the as synthesized sample. Raman Spectroscopic investigation was carried out to confirm the in-plane blending of SnO2 and graphene inside the composite matrix. The as-prepared ternary-phase Bi@SnO2@G-based photocatalyst showed high degradation efficiency of 99.6% and 94.5% for direct blue (DB) and methyl blue (MB) dyes, respectively, under visible light irradiation by (i) minimizing the hole and electron recombination, (ii) providing a high surface area, and (iii) reducing the band gap energy. This study provides an effective, low-cost, and smart approach for producing GNs on a wide scale from battery waste along with nanohybrid composites with high photocatalytic efficiency.

Ulva lactuca L. extract bio-templated fabrication of CuO/ZnFe2O4 nanocomposites for photodegradation organic dye pollutants and in vitro biological activities

In this present work, a novel CuO/ZnFe2O4 nanocomposites has been fabricated via hydrothermal-assisted synthesis using Ulva lactuca L. extract as both a reducing and capping agent A comprehensive investigation such as structural, morphological, optical, and electronic properties of the CuO/ZnFe2O4 NCs were investigated in details. The photocatalytic efficacy of the prepared CuO/ZnFe2O4 NCs was assessed for Congo red (CR) dye degradation and the experimental results demonstrate the CuO/ZnFe2O4 NCs exhibits superior photocatalytic activity (91.13% k=0.03289 min−1) compared to pure CuO and ZnFe2O4 catalysts under 120 min of visible light irradiation. Additionally, the CuO/ZnFe2O4 NCs exhibited excellent long-term recycling stability over four consecutive cycles. This enhanced photocatalytic performance of CuO/ZnFe2O4 NCs was attributed to the synergism between CuO and ZnFe2O4, which facilitate the exceptional properties such as large specific area, a wide visible-light absorption range, and efficient electron-hole separation. Furthermore, the prepared CuO/ZnFe2O4 NCs were evaluated for their in vitro antibacterial and anticancer properties. The results of the disc diffusion assay with CuO/ZnFe2O4 NCs as an antibacterial agent demonstrated a highest zone of inhibition of 18.23 ± 0.30 mm for Bacillus subtilis and 19.83 ± 0.76 mm Escherichia coli. Moreover, in vitro cytotoxicity assessments using the MTT assay indicated a 64.94% cytotoxic activity against HT-29 colon cancer cells. The multifunctional advantages of Ulva lactuca L. extract-mediated green CuO/ZnFe2O4 NCs hold significant promise for environmental remediation and in vitro-based therapeutic applications.