Synthesis, characterization and photocatalytic activity of ZSM-5/ZnO nanocomposite modified by Ag nanoparticles for methyl orange degradation

Preparation and Spectrochemical characterization of Ni-doped ZnS nanocomposite for effective removal of emerging contaminants and hydrogen Production: Reaction Kinetics, mechanistic insights

In this study, we report the successful synthesis of Ni-doped ZnS nanocomposite via a green route using ethanolic crude extract of Avena fatua. The as-synthesized nanocomposite was comprehensively characterized using Dynamic light scattering (DLS), Zeta potential, scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and Atomic force microscopy (AFM). These analyses provided detailed insights into the size, morphology, composition, surface properties, and structural characteristics of the nanocomposite. Subsequently, the synthesized nanocomposite was evaluated for their photocatalytic performance against the organic dye Methyl orange. Remarkably, the nanocomposite exhibited rapid and efficient degradation of Methyl orange, achieving 90 % degradation within only 30 min of irradiation under UV light. Moreover, the photocatalyst demonstrated an exceptional hydrogen production rate, reaching 167.73 µmolg-1h-1, which is approximately 4.5 times higher than that of its pristine counterparts. These findings highlight the significant potential of Ni-doped ZnS nanocomposite as highly efficient photocatalysts for wastewater treatment and hydrogen production applications.

MgO Nanoparticles as a Promising Photocatalyst towards Rhodamine B and Rhodamine 6G Degradation

The increasing global requirement for clean and safe drinking water has necessitated the development of efficient methods for the elimination of organic contaminants, especially dyes, from wastewater. This study reports the synthesis of magnesium oxide (MgO) nanoparticles via a simple precipitation approach and their thorough characterization using various techniques, including XRD, FT-IR, XPS, TGA, DLS, and FESEM. Synthesized MgO nanoparticles' photocatalytic effectiveness was evaluated towards rhodamine B and rhodamine 6G degradation under both UV and visible light irradiation. The results indicated that the MgO nanoparticles possess a face-centered cubic structure with enhanced crystallinity and purity, as well as an average crystallite size of approximately 3.20 nm. The nanoparticles demonstrated a significant BET surface area (52 m2/g) and a bandgap value equal to 5.27 eV. Photocatalytic experiments indicated complete degradation of rhodamine B dye under UV light within 180 min and 83.23% degradation under visible light. For rhodamine 6G, the degradation efficiency was 92.62% under UV light and 38.71% under visible light, thus verifying the MgO catalyst's selectivity towards degradation of rhodamine B dye. Also, reusability of MgO was investigated for five experimental photocatalytic trials with very promising results, mainly against rhodamine B. Scavenging experiments confirmed that •OH radicals were the major reactive oxygen species involved in the photodegradation procedure, unraveling the molecular mechanism of the photocatalytic efficiency of MgO.

Fabrication of a reusable carbon quantum dots (CQDs) modified nanocomposite with enhanced visible light photocatalytic activity

In awareness of industrial dye wastewater, carbon quantum dots (CQDs) and cobalt zinc ferrite (CZF) nanocomposites were synthesised for the making of carbon quantum dots coated cobalt zinc ferrite (CZF@CQDs) nanophotocatalyst using oxidative polymerization reaction. The results of TEM, zeta potential value, and FTIR confirm highly dispersed 1-4 nm particles with the - 45.7 mV carboxylic functionalized surface of CQDs. The results of the synthesised CZF@CQDs photocatalyst showed an average particle size of ~ 15 nm according to TEM, SEM, and XRD. The photocatalyst showed a 1.20 eV band gap, which followed the perfect visible light irradiation. TGA and DTA revealed the good thermal stability of the nanophotocatalyst. VSM was carried out, and the saturation magnetisations for CZF and CZF@CQDs were 42.44 and 36.14 emu/g, respectively. A multipoint study determined the BET-specific surface area of the CZF@CQDs photocatalyst to be 149.87 m2/g. Under visible light irradiation, the final CZF@CQDs nanophotocatalyst demonstrated remarkable efficiency (~ 95% within 25 min) in the photocatalytic destruction of Reactive Blue 222 (RB 222) and Reactive Yellow 145 (RY 145) dyes, as well as mechanical stability and recyclability. Even after the recycling of the degradation study, the nanophotocatalyst efficiency (~ 82%, 7th cycles) was predominantly maintained. The effects of several parameters were also investigated, including initial dye concentration, nanophotocatalyst concentration, CQD content, initial pH of the dye solution, and reaction kinetics. Degradation study data follow the first-order reaction rate (R2 > 0.93). Finally, a simple and low-cost synthesis approach, rapid degradation, and outstanding stability of the CQD-coated CZF nanophotocatalyst should make it a potential photocatalyst for dye wastewater treatment.

Enhanced mitigation of acidic and basic dyes by ZnO based nano-photocatalysis: current applications and future perspectives

Dye wastewater possess immense toxicity with carcinogenic properties and they persist in environment owing to their stability and resistance to chemical and photochemical changes. The bio degradability of dye-contaminated wastewater is low due to its complex molecular structure. Nano-photocatalysts based on zinc oxide are reported as one of the effective metal oxides for dye remediation due to their photostability, enhanced UV and visible absorption capabilities in an affordable manner. An electron-hole pair forms when electrons in the valence band of ZnO nano-photocatalyst transfer into the conduction band by absorbing UV light. The review article presents a detailed review on ZnO applications for treating acidic and basic dyes along with the dye degradation performance based on operating conditions and photocatalytic kinetic models. Several acidic and basic dyes have been shown to degrade efficiently using ZnO and its nanocomposites. Higher removal percentages for crystal violet was reported at pH 12 by ZnO/Graphene oxide catalyst under 400 nm UV light, whereas acidic dye Rhodamine B at a pH of 5.8 was degraded to 100% by pristine ZnO. The mechanism of action of ZnO nanocatalysts in degrading the dye contamination are reported and the research gaps to make these agents in environmental remediation on real time operations are discussed.

Efficient photocatalytic remediation of lerui acid brilliant blue dye using radiation- prepared carboxymethyl cellulose/acrylic acid hydrogel supported by ZnO@Ag

Organic dye pollution from textiles and other industries presents a substantial risk to people and aquatic life. The use of photocatalysis to decolorize water using the strength of UV light is one of the most important remediation techniques. In the present study, a novel nanocomposites hydrogel including carboxymethyl cellulose (CMC), acrylic acid (AAc), Zinc oxide (ZnO), and silver (Ag) nanoparticles was produced using an eco-friendly γ-irradiation technique for photocatalytic decolorization applications. ZnO and Ag nanoparticles were distributed in the CMC/AAc hydrogel matrix without significant aggregation. SEM, XRD, EDX, TEM, and FTIR analyses were used to assess the physicochemical characteristics of the nanocomposite samples. Carboxymethyl cellulose/acrylic acid/Zinc oxide doped silver (CMC/PAAc/ZnO@Ag) nanocomposite hydrogels were developed and utilized in the photocatalytic decolorization of the lerui acid brilliant blue dye (LABB) when exposed to ultraviolet (UV) radiation. UV- Vis spectrophotometry was utilized to analyze the optical properties of the produced nanostructure. Regarding the decolorization of the LABB, the impacts of operational variables were investigated. The optimum conditions for decolorization (93 %) were an initial concentration of 50 mg/L, pH = 4, catalyst dosage of 50 g/L, and exposure time of 90 min. The results illustrated that the LABB acidic dye from wastewater was remarkably decolored.

Rapid determination of 61 acid dyes in chili paste, hotpot seasoning, and bearnaise using double liquid-liquid extraction and UHPLC-Q-Orbitrap-MS

The aims of this study were to establish a novel method for simultaneously determining 61 acid dyes in chili, hotpot seasoning, and bearnaise sauce using double liquid-liquid extraction (d-LLE) technology. A mixture of water, methanol, and dichloromethane (1:3:1, v/v/v) was used as the extraction solution, which was actively separated into aqueous and organic phases at a fixed ratio. The clean-up step was initially completed by discarding the organic phase layer, which contained abundant lipophilic compounds. Subsequently, the aqueous phase was further separated by salting out, which effectively removed interference from the highly hydrophilic compounds. As a result of these two purification steps, the matrix suppression effect was significantly reduced by a minimum of 16.9%. Finally, the extract was analyzed using an ultrahigh-performance liquid chromatography-quadrupole Orbitrap mass spectrometer (UHPLC-Q-Orbitrap-MS), and the characteristic ion fragments (SO3 - , m/z 79.9557) of the acid dyes were utilized for the preliminary qualitative analysis. The results showed that the 61 acid dyes showed a good linear relationship in the range of 0.01-0.2 µg/mL, and the limit of quantification (LOQ) was 0.01 mg/kg. The average recoveries were 74.3%-99.7%, with relative standard deviations (RSD) ≤10%. The proposed method can rapidly identify and quantify acid dyes in complex foods at a low cost, with high sensitivity and reliability.

Synthesis of novel antibacterial nanocomposite CuO/Ag-modified zeolite for removal of MB dye

Novel CuO/Ag nanocomposites added zeolite (CAZ) were successfully fabricated, and their effectiveness as an antibacterial on S. aureus and MB removal was evaluated. EDX, XRD, and FTIR confirm the presence of the elemental compositions of CAZ. Friable CuO nanorods (10-70 nm in diameter) existed on the surface of the zeolite. Pure zeolite had a higher band gap (5.433 eV) and lower MB removal efficiency than CAZ. The adsorption method by CAZ was more effective at removing MB than photodegradation. 0.10 CAZ had the highest removal effectiveness (~ 99%) and adsorption capacity (~ 70.4 mg g-1) of MB. The inhibitory zone diameter for 0.005 CAZ against S. aureus was 20 mm, while 0.01 CAZ had a diameter of 17 mm. Azithromycin, ceftriaxone, and erythromycin antibiotics demonstrated lower or no efficacy against S. aureus than CAZ. Significant antibacterial activities and wastewater treatment were achieved by CAZ. The combination of photodegradation and adsorption enhanced pollutant removal. It will be interesting to study further the optimal molar ratio for MB removal (0.10 CAZ) in future investigations.

Role of Delocalization, Asymmetric Distribution of π-Electrons and Elongated Conjugation System for Enhancement of NLO Response of Open Form of Spiropyran-Based Thermochromes

Switchable nonlinear optical (NLO) materials have widespread applications in electronics and optoelectronics. Thermo-switches generate many times higher NLO responses as compared to photo-switches. Herein, we have investigated the geometric, electronic, and nonlinear optical properties of spiropyranes thermochromes via DFT methods. The stabilities of close and open isomers of selected spiropyranes are investigated through relative energies. Electronic properties are studied through frontier molecular orbitals (FMOs) analysis. The lower HOMO-LUMO energy gap and lower excitation energy are observed for open isomers of spiropyranes, which imparts the large first hyperpolarizability value. The delocalization of π-electrons, asymmetric distribution and elongated conjugation system are dominant factors for high hyperpolarizability values of open isomers. For deep understanding, we also analyzed the frequency-dependent hyperpolarizability and refractive index of considered thermochromes. The NLO response increased significantly with increasing frequency. Among all those compounds, the highest refractive index value is observed for the open isomer of the spiropyran 1 (1.99 × 10-17 cm2/W). Molecular absorption analysis confirmed the electronic excitation in the open isomers compared to closed isomers. The results show that reversible thermochromic compounds act as excellent NLO molecular switches and can be used to design advanced electronics.

Application of zeolite based nanocomposites for wastewater remediation: Evaluating newer and environmentally benign approaches

The presence of heavy metal ions and emerging pollutants in water poses a great risk to various biological ecosystems as a result of their high toxicity. Consequently, devising efficient and environmentally friendly methods to decontaminate these waters is of high interest to many researchers around the world. Among the varied water treatment and desalination means, adsorption and photocatalysis have been widely employed. However, the discussion and analysis of the use of zeolite-based composites as adsorbents are somehow minimal. The porous aluminosilicates (zeolites) are excellent candidates in wastewater treatment owing to various mechanisms of pollutants removal that they possess. The purpose of this review is thus to provide a synopsis of the current developments in the fabrication and application of nanocomposites based on zeolite as adsorbents and photocatalysts for the extraction of heavy metals, dyes and emerging pollutants from wastewaters. The review goes on to look into the effect of weight ratio on photocatalyst, photodegradation pathways, and various factors that influence photocatalysis and adsorption.

The Promising Antibacterial and Anticancer Activity of Green Synthesized Zinc Nanoparticles in Combination with Silver and Gold Nanoparticles

Zinc nanoparticles (ZnNPs) are showing promising medical applications. However, their cytotoxicity is relatively high. This study aims to use a green synthesis technique based on the natural propolis (honeybees glue) and produce three counterparts of Zinc nanoparticles (ZnO-NPs, AuNPs@ZnO and AgNPs@ZnO). Then, the three would be analyzed for their potential antibacterial activity and cytotoxicity. The study compares the antibacterial activity and cytotoxicity of ZnO-NPs alone to its combination with gold and silver (AuNPs@ZnO and AgNPs@ZnO). The results showed that AgNPs@ZnO had contributed significantly to antibacterial activity against Gram-positive and Gram-negative bacteria. Moreover, AuNPs@ZnO and AgNPs@ZnO showed similar cytotoxicity to ZnO-NPs with higher safety. Furthermore, the Scanning and Transmission Electron Microscopes’ micrographs (SEM and TEM) displayed the biosynthesized ZnNPs that have a spherical shape with sizes ranging from 17 to 70 nm, from 45 to 75 nm, and from 22 to 73 nm for ZnONPs, ZnO-AgNPs, free AgNPs, and ZnO-AuNPs, respectively. In addition, zeta potential values for ZnONPs were 11.4 mV, while ZnO-AgNPs and ZnO-AuNPs have a higher overall charge of 13.6 mV and 23.9 mV, respectively. Furthermore, ZnNPs exhibited antibacterial activity, yet AgNPs@ZnO demonstrated the highest antibacterial action against Gram-negative and Gram-positive bacteria. In addition, cytotoxicity analyses of biosynthesized ZnNPs on three cell lines; breast cancer cell (MCF-7), liver cancer cell (HepG-2) and Human skin fibroblast (HSF) revealed that Zn-NPs in a combination could function as an anticancer agent. Therefore, there are promising medical applications for the biosynthesized ZnNPs in combinations with other metals, such as ZnO-AgNPs, as safe antibacterial and anticancer medicines.

Graphical Abstract

The Ultrahigh Adsorption Capacity and Excellent Photocatalytic Degradation Activity of Mesoporous CuO with Novel Architecture

In this paper, mesoporous CuO with a novel architecture was synthesized through a conventional hydrothermal approach followed by a facile sintering procedure. HR-TEM analysis found that mesoporous CuO with an interconnected pore structure has exposed high-energy crystal planes of (002) and (200). Theoretical calculations indicated that the high-energy crystal planes have superior adsorption capacity for H⁺ ions, which is critical for the excellent adsorption and remarkable photocatalytic activity of the anionic dye. The adsorption capacity of CuO to methyl orange (MO) at 0.4 g/L was approximately 30% under adsorption equilibrium conditions. We propose a state-changing mechanism to analyze the synergy and mutual restraint relation among the catalyst CuO, H⁺ ions, dye and H₂O₂. According to this mechanism, the degradation rate of MO can be elevated 3.5 times only by regulating the MO ratio in three states.

Heterogeneous Cu2O-Au nanocatalyst anchored on wood and its insight for synergistic photodegradation of organic pollutants

In this study, a Cu₂O-Au nanoparticles (NPs) heterojunction catalyst anchored on wood was developed by in situ reduction and hydrothermal treatment, and the properties of the catalyst were systematically characterized. The catalyst exhibited prominent photocatalysis of methyl orange (MO, 0.169 min^{- 1}), and tetracycline (TC, 0.122 min^-1) which were degraded completely within 20 min. Even after four recyclings, the efficiency of MO degradation by the catalyst remained at 80%. The natural wood with three-dimensional porous structures acted as a reducing agent and a stabilizer for Au NPs and Cu₂O, which helped to maintain high performance and reusability. The presence of Au NPs mediated the light-induced electron transfer and enhanced the absorption of visible light for promoting photocatalytic activity. The intermediates of contaminants within the degradation process were characterized by liquid chromatography-mass spectrometry. Additionally, the photogenerated superoxide radicals and holes were identified by electron spin resonance. Thus, the potential degradation mechanism catalyzed by the Cu₂O-Au NPs-wood was proposed. This findings of this study valorizes biomass as a photocatalyst for wastewater remediation.

Rapid determination of 93 banned industrial dyes in beverage, fish, cookie using solid-supported liquid-liquid extraction and ultrahigh-performance liquid chromatography quadrupole orbitrap high-resolution mass spectrometry

Banned industrial dyes are composed of a large number of chemicals with diverse physical and chemical properties, making their simultaneous determination a challenging task. A one-step extraction and purification of 93 banned industrial dyes from beverage, fish and cookie sample methods was proposed by using solid supported liquid-liquid extraction (SLE). The extract was analyzed by ultrahigh-performance liquid chromatography quadrupole orbitrap high-resolution mass spectrometry (UPLC-Q-Orbitrap-HRMS). The quantitative and qualitative mode adopts Q-Orbitrap-HRMS full scan MS (full scan MS¹) and data-dependent MS/MS (dd-MS²) acquisition mode. The mass resolution was screened under 70,000 FWHM for full-scan MS¹ and 35,000 FWHM for dd-MS². Linearity was observed in the range of 0.01 ∼ 0.5 μg/mL and the limits of quantification were 0.04 ∼ 0.2 mg/kg for 93 dyes. The average recoveries were 70.5-105.8%, with RSD ≤ 10%. The proposed method has the ability to simultaneously screen many banned dyes in foods with high throughput, sensitivity and reliability.

Remarkable Recycling Process of ZnO Quantum Dots for Photodegradation of Reactive Yellow Dye and Solar Photocatalytic Treatment Process of Industrial Wastewater

The mineralization of five industrial sunlight-exposed wastewater samples was investigated, and the recycling process of ZnO quantum dots (ZQDs) for five reusable times was estimated under the approved Egyptian Environmental Law COD (Chemical Oxygen Demand), which has to be less than 1000 ppm. An improved sol-gel process at a low calcination temperature that ranged between 350 and 450 °C was employed to synthesize ZnO quantum dots (ZQDs). The purity, high crystallinity, and structure of the prepared catalysts were determined by TEM and XRD analysis. The energy bandgap, the crystal size values, and the surface area for Z1 and Z2 were determined based on the TEMs, DRSs, and EBTs, which were equal to 6.9 nm, 3.49 eV, and 160.95 m2/g for Z1 and 8.3 nm, 3.44 eV, and 122.15 m2/g for Z2. The investigation of the prepared samples was carried out by studying the photocatalytic activity and photoluminescence, and it was found that the degradation rate of reactive yellow dye as an industrial pollutant of the Z1 sample was significantly higher than other samples, by 20%. The data collection has shown that photocatalytic efficiency decreases with an increase in the crystallite size of ZQDs.

A polyurethane foam membrane filled with double cross-linked chitosan/carboxymethyl cellulose gel and decorated with ZSM-5 nano zeolite: Simultaneous dye removal

A novel bio-based polyurethane foam was fabricated using double cross-linked chitosan/carboxymethyl cellulose gel, filled with ZSM-5 nano zeolite, and hot-pressed into the membrane. The prepared foam membrane was characterized using FESEM, FTIR, BET, TGA, and pH_ZPC analyses and then used for continuous dye removal. The results modification of polyurethane foam with chitosan/carboxymethyl cellulose gel and ZSM-5 nano zeolite would increase the retention ability of positive cationic methylene blue. Also, the foam could simultaneously remove methyl orange, eriochrome black T, and methylene blue from the binary and trinary solutions but could effectively be used to selectively removal methylene blue. In addition, the dye removal ability at the breakthrough was enhanced with decreasing flow rate, and increasing bed height, pH, initial dye concentration, and nano zeolite content in the foam. To describe the breakthrough curves different models were utilized which best fits were obtained with Modified Dose-Response as compared to Thomas, Adams & Bohart, Yoon-Nelson, and Wolborska models.

Enhanced photocatalytic activity of ZnO hexagonal tube/r-GO composite on degradation of organic aqueous pollutant and study of charge transport properties

ZnO hexagonal tube and ZnO/r-GO nanocomposites were synthesized by hydrothermal method and the nanostructures were characterized by XRD, UV-DRS, PL, FTIR, FESEM, and TEM techniques. The main violet emission peak of the synthesized nanostructures is due to the transition between interstitial zinc and hole (valence band) of ZnO. The potential of ZnO/r-GO nanocomposite was evaluated using methyl orange (MO) and rhodamine-B (RhB), and the results were compared with the activity of synthesized ZnO nanostructures. More than 95% of MO and RhB were by ZnO/r-GO nanocomposite and it was found to be higher than that of ZnO hexagonal tube. The degradation MO and RhB were found to follow first-order kinetics and it has a rate constant of 7.68 × 10^-2and 7.83 × 10^-2 min^-1, respectively. These results are mainly due to the enhanced charge transport property. Trapping experiments show that superoxide radical anion and hydroxide radicals are chief species responsible for the degradation of MO and RhB. The chemical stability of the nanocomposite was evaluated by cycle test experiments and it reveals that the catalyst can be reused up to few cycles without considerable loss of photocatalytic activity. This work affords a simple stratagem to integrate ZnO hexagonal tubes and r-GO nanosheets to construct effective catalysts for the degradation of organic compounds.

Effective Disposal of Methylene Blue and Bactericidal Benefits of Using GO-Doped MnO2 Nanorods Synthesized through One-Pot Synthesis

Graphene oxide (GO)-doped MnO2 nanorods loaded with 2, 4, and 6% GO were synthesized via the chemical precipitation route at room temperature. The aim of this work was to determine the catalytic and bactericidal activities of prepared nanocomposites. Structural, optical, and morphological properties as well as elemental composition of samples were investigated with advanced techniques such as X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, UV-visible (vis) spectroscopy, photoluminescence (PL), energy-dispersive spectrometry (EDS), and high-resolution transmission electron microscopy (HR-TEM). XRD measurements confirmed the monoclinic structure of MnO2. Vibrational mode and rotational mode of functional groups (O-H, C=C, C-O, and Mn-O) were evaluated using FTIR results. Band gap energy and blueshift in the absorption spectra of MnO2 and GO-doped MnO2 were identified with UV-vis spectroscopy. Emission spectra were attained using PL spectroscopy, whereas elemental composition of prepared materials was recorded with scanning electron microscopy (SEM)-EDS. Moreover, HR-TEM micrographs of doped and undoped MnO2 revealed elongated nanorod-like structure. Efficient degradation of methylene blue enhanced the catalytic activity in the presence of a reducing agent (NaBH4); this was attributed to the implantation of GO on MnO2 nanorods. Furthermore, substantial inhibition areas were measured for Escherichia coli (EC) ranging 2.10-2.85 mm and 2.50-3.15 mm at decreased and increased levels for doped MnO2 nanorods and 3.05-4.25 mm and 4.20-5.15 mm for both attentions against SA, respectively. In silico molecular docking studies suggested the inhibition of FabH and DNA gyrase of E. coli and Staphylococcus aureus as a possible mechanism behind the bactericidal activity of MnO2 and MnO2-doped GO nanoparticles (NPs).

Photocatalytic Dye Degradation and Biological Activities of Cu-Doped ZnSe Nanoparticles and Their Insights

Environmental nanotechnology has received much attention owing to its implications on environmental ecosystem, and thus is promising for the elimination of toxic elements from the aquatic surface. This work focuses on Cu-doped ZnSe nanoparticles using the co-precipitation method. The synthesized Cu-doped ZnSe nanoparticles were examined for structural, optical, and morphological properties with the help of XRD, FTIR, UV/vis diffuse reflection spectroscopy (DRS), FESEM, TEM, and XPS. The synthesized Cu-doped ZnSe nanoparticles revealed the presence of Cu2+ in the ZnSe lattice, which has been shown to take a predominant role for enhanced catalysis in the Cu-doped ZnSe nanoparticles. The synthesized Cu-doped ZnSe nanoparticles were investigated for their catalytic and antibacterial activities. The 0.1 M copper-doped ZnSe nanoparticles exhibited the highest rate of degradation against the methyl orange dye, which was found to be 87%. A pseudo-first-order kinetics was followed by Cu-doped ZnSe nanoparticles with a rate constant of 0.1334 min−1. The gram-positive and gram-negative bacteria were used for investigating the anti-bacterial activity of the Cu-doped ZnSe nanoparticles. The Cu-doped ZnSe nanoparticles exhibited enhanced photocatalytic and antibacterial activity.

Straightforward Synthesis of Mn3O4/ZnO/Eu2O3-Based Ternary Heterostructure Nano-Photocatalyst and Its Application for the Photodegradation of Methyl Orange and Methylene Blue Dyes

Zinc oxide-ternary heterostructure Mn₃O₄/ZnO/Eu₂O₃ nanocomposites were successfully prepared via waste curd as fuel by a facile one-pot combustion procedure. The fabricated heterostructures were characterized utilizing XRD, UV-Visible, FT-IR, FE-SEM, HRTEM and EDX analysis. The photocatalytic degradation efficacy of the synthesized ternary nanocomposite was evaluated utilizing model organic pollutants of methylene blue (MB) and methyl orange (MO) in water as examples of cationic dyes and anionic dyes, respectively, under natural solar irradiation. The effect of various experimental factors, viz. the effect of a light source, catalyst dosage, irradiation time, pH of dye solution and dye concentration on the photodegradation activity, was systematically studied. The ternary Mn₃O₄/ZnO/Eu₂O₃ photocatalyst exhibited excellent MB and MO degradation activity of 98% and 96%, respectively, at 150 min under natural sunlight irradiation. Experiments further conclude that the fabricated nanocomposite exhibits pH-dependent photocatalytic efficacy, and for best results, concentrations of dye and catalysts have to be maintained in a specific range. The prepared photocatalysts are exemplary and could be employed for wastewater handling and several ecological applications.

Utilization of red mud waste into mesoporous ZSM-5 for methylene blue adsorption-desorption studies

Red mud as industrial waste from bauxite was utilized as a precursor for the synthesis of mesoporous ZSM-5. A high concentration of iron oxide in red mud was successfully removed using alkali fusion treatment. Mesoporous ZSM-5 was synthesized using cetyltrimethylammonium bromide (CTABr) as a template via dual-hydrothermal method, and the effect of crystallization time was investigated towards the formation of mesopores. Characterization using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N₂ adsorption-desorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) indicated the formation of cubic crystallite ZSM-5 with high surface area and mesopore volume within 6 h of crystallization. Increasing the crystallization time revealed the evolution of highly crystalline ZSM-5; however, the surface area and mesoporosity were significantly reduced. The effect of mesoporosity was investigated on the adsorption of methylene blue (MB). Kinetic and thermodynamic analysis of MB adsorption on mesoporous ZSM-5 was carried out at a variation of adsorption parameters such as the concentration of MB solution, the temperatures of solution, and the amount of adsorbent. Finally, methanol, 1-butanol, acetone, hydrochloric acid (HCl), and acetonitrile were used as desorbing agents to investigate the reusability and stability of mesoporous ZSM-5 as an adsorbent for MB removal.

Synthesis and Photocatalytic Activity of Hierarchical Zn-ZSM-5 Structures

Hierarchical Zn-ZSM-5 photocatalyst structures were synthesized via a hydrothermal one-pot synthesis route using a double template. Activated attapulgite (Si-ATP) and zinc nitrate (Zn(NO3)2) precursors were used as silicon and zinc sources, respectively. The structural properties, morphology, photocatalytic activity and the texture properties of the synthesized Zn-ZSM-5 photocatalysts were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), diffracted ultraviolet–visible (UV–Vis) spectrometry (DRUV–Vis) and N2 adsorption/desorption, respectively. It was found that the composites exhibit a typical MFI framework structure, a hexahedral twin structure and typical UV absorption peaks at 292 nm and 246 nm, when the Zn/Si mole ratio reaches its optimum value of 1:100. The hierarchical nanocrystals exhibit a similar Brunauer–Emmett–Teller surface area (309 m2 g−1) and a high mesopore ratio (37.47%) as compared to commercial zeolites. Sub-nano-sized zinc oxide (ZnO) particles with small size moieties were implanted and isolated in the silica matrices of micro-mesoporous zeolite, which had a significant photocatalytic activity and reusability of degrading methylene blue (MB) dyeing wastewater. Using a 500 W mercury lamp with the wavelength range from 185–500 nm operating during an illumination time of 30 min, the concentration of MB decreases significantly in the presence of Zn-ZSM-5 photocatalyst leading to a 95.56% of degradation, where the ratio still remained at 94.32% after six times of reuse.

Nanoparticulate Double-Heterojunction Photocatalysts Comprising TiO2(Anatase)/WO3/TiO2(Rutile) with Enhanced Photocatalytic Activity toward the Degradation of Methyl Orange under Near-Ultraviolet and Visible Light

Nanoparticulate double-heterojunction photocatalysts comprising TiO_2(Anatase)/WO₃/TiO_2(Rutile) were produced by a sol-gel method. The resulting photocatalysts exhibit clear synergistic effects when tested toward the degradation of methyl orange under both UV and visible light. Kinetic studies indicate that the degradation rate on the best double-heterojunction photocatalyst (10 wt % WO₃-TiO₂) depends mainly on the amount of dye concentration, contrary to pure oxides in which the degradation rate is limited by diffusion-controlled processes. The synergistic effects were confirmed through systematic and careful studies including holes and OH radical formation, X-ray diffraction, electron microscopy, elemental analysis, UV-vis diffuse reflectance spectroscopy, and surface area analysis. Our results indicate that the successful formation of a double heterojunction in the TiO_2(Anatase)/WO₃/TiO_2(Rutile) system leads to enhanced photoactivity when compared to individual oxides and commercial TiO₂ P25.

Recycling for solar photocatalytic activity of Dianix blue dye and real industrial wastewater treatment process by zinc oxide quantum dots synthesized by solvothermal method

Solar photocatalytic activity of zinc oxide quantum dots (ZOQDs) was investigated and two samples of ZOQDs were synthesized by solvothermal method and characterized using different spectroscopic techniques. Crystal and morphological properties were obtained from XRD and HRTEM showed the purity, high crystallinity single phase and the elongated shape of prepared quantum dots. The measured crystallite size of the S1 and S2 samples is 8.4 and 9.6 nm respectively. The results of BET analysis and the optical properties of the samples shown that the first sample have larger values for both the specific surface area and band gap energy. Estimation of the photocatalytic performance indicated that the first sample give the best degradation rate of the synthetic Dianix Blue dye (DB) dye (2.47 × 10^-2 s^-1). Likewise, in the photo-oxidation of coumarin, the sample with the smallest particle size achieves the highest by 20% fluorescence rate than the largest particle size sample. In addition, the work included a study of the mineralization and recycling efficiency of industrial wastewater as a study case in the presence of different doses of ZOQDs by sun light for a one year and this evaluation done according to Egyptian allowed COD limit according to local environmental ministry law.

Novel CoFe2O4@ZnO-CeO2 ternary nanocomposite: Sonochemical green synthesis using Crataegus microphylla extract, characterization and their application in catalytic and antibacterial activities

In this study, CoFe₂O₄@ZnO-CeO₂ magnetic nanocomposite (CoFe@Zn-Ce MNC) was successfully prepared by facile sonochemical method for the first time. CoFe@Zn-Ce MNC was obtained by green and cost-effective process in the presence of Crataegus microphylla (C. microphylla) fruit extract. Influence of some parameters like capping agents (C. microphylla, SDS and CTAB), sonication time (10, 30 and 60 min) and sonication power (40, 60 and 80 W) were studied to achieve optimum condition. The as-obtained products were characterized by FT-IR, FESEM, TEM, DRS, VSM, EDS, TGA and XRD analysis. Results showed that high magnetic properties (20.38 emug^-1), 70-80 nm size and spherical morphology were unique characteristics of synthesized nanocomposite. Antibacterial activity of CoFe@Zn-Ce MNC was examined against E. coli, P. aeruginoss and S. aureus bacteria. Among theme, S. aureus as gram-positive bacteria showed excellent antibacterial activity. Furthermore, photocatalytic performance of the CoFe@Zn-Ce MNC was investigated by degradation of humic acid (HA) molecules under visible and UV light irradiations. The influence of morphology of products and incorporation of cerium oxide with CoFe₂O₄@ZnO on photocatalytic activity of CoFe₂O₄@ZnO was performed. After 100 min illumination, the decomposition of HA pollutant by magnetic nanocomposite were 97.2% and 72.4% under exposure of UV and visible light irradiations, respectively. Also, CoFe@Zn-Ce MNC demonstrated high stability in the cycling decomposition experiment after six times cycling runs.

Dielectric barrier discharge plasma with photocatalysts as a hybrid emerging technology for degradation of synthetic organic compounds in aqueous environments: A critical review

Dielectric barrier discharge (DBD) plasma has been recently used for removal of synthetic organic compounds (SOCs) from aqueous environments. The removal of SOCs by alone DBD is significantly limited by its high electricity needs and inefficient mineralization, which affects the further application of DBD for SOCs. The combined application of DBD with other technologies and the addition of a supplementary substance for energy-saving were proposed to resolve these problems. The addition of catalysts is considered to be a promising and innovative approach to increase the energy yield of DBD, improve the environment friendly of DBD, develop the variety of goal SOCs, and improve the removal efficiency of DBD system. Despite the increasing use of the coupling form of DBD and catalysts, as catalytic dielectric barrier discharge (CDBD), but it still requires a comprehensive review to summarize the last studies and highlight the future perspectives in this area. Therefore, this work is the first literature review aimed to critically assess the latest developments of catalysts coupling with DBD employed in aqueous environments. Moreover, performance evaluation, energy yield, toxicity, eco-friendly, and future perspectives of the CDBD systems for SOCs removal were discussed and overviewed. The results showed that the coupling of catalysts with DBD presents synergistic effects and had excellent removal performance for aqueous SOCs. Overall, it can be concluded that the essential principles of environmental and economic sustainability have been addressed for the removal of persistent pollutants from aqueous environments in the CDBD systems.

Photocatalytic degradation of methyl orange from wastewater using a newly developed Fe-Cu-Zn-ZSM-5 catalyst

Photo-Fenton oxidation is one of the most promising processes to remove recalcitrant contaminants from industrial wastewater. In this study, we developed a novel heterogeneous catalyst to enhance photo-Fenton oxidation. Multi-composition (Fe-Cu-Zn) on aluminosilicate zeolite (ZSM-5) was prepared using a chemical process. Subsequently, the synthesized catalyst was characterized by using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), high-resolution transmission electron microscopy (HRTEM), energy dispersive X-ray (spectroscopy) (EDX), and Brunauer-Emmett-Teller (BET). Activity of the synthesized catalyst is analysed to degrade an azo dye, methyl orange. Taguchi method is used to optimize color removal and total carbon content (TOC) removal. The dye completely degraded, and 76% of TOC removal was obtained at optimized process conditions. The amount of catalyst required for the desired degradation of dye significantly reduced up to 92% and 30% compared to conventional homogenous and heterogeneous Fenton oxidation processes, respectively.

C-Dot TiO2 nanorod composite for enhanced quantum efficiency under direct sunlight

Watermelon rind-derived C-dots were prepared via a facile route and decorated on Ti nanorods for enhanced electron mobilisation and visible light utilisation.