A facile solvothermal syntheses of NiFe layered double hydroxide-Bi2MoO6 heterostructure/reduced graphene oxide with efficient photodegradation for tetracycline

Synthesis and characterization of new composite from modified silica-coated MnFe2O4 nanoparticles for removal of tetracycline from aqueous solution

In this study, a new composite from silica coated MnFe2O4 nanoparticles, diethylenetriamine, 3-chloropropyl trimethoxysilane and Mg-Al Layered Double Hydroxide (Mg-Al LDH/DETA/CPTMS/SCNPs) composite was synthesized. The Mg-Al LDH/DETA/CPTMS/SCNPs composite was examined by Fourier transform infrared spectrometer (FT-IR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDS), X-ray diffraction (XRD), Thermogravimetric Analysis (TGA) and Vibrating Sample Magnetometry (VSM). The synthesized composite exhibited magnetic property with a saturation magnetization of 0.40 emu g-1. The Mg-Al LDH/DETA/CPTMS/SCNPs composite was utilized as a successful adsorbent for removal of tetracycline from aqueous solutions. The effect of various operation factors such as initial drug concentration, adsorbent dosage, pH and contact time were investigated. The optimized variable conditions such as adsorbent dose of 60 mg L-1, drug concentration of 100 mg L-1, pH = 7 and contact time 30 min were obtained. For describing the adsorption isotherms, the Langmuir, Freundlich and Temkin adsorption models were utilized. The results indicated that the adsorption isotherm is in good agreement with Langmuir model. According to the Langmuir analysis, the maximum adsorption capacity (qm) of the Mg-Al LDH/DETA/CPTMS/SCNPs composite for tetracycline was obtained to be 40.16 mg g-1. The kinetic studies revealed that the adsorption in all cases to be a pseudo second-order process. The negative value of ΔG° and the positive value of ΔH° showed the adsorption process to be spontaneous and endothermic.

Visible light-driven sliver-modified titanium dioxide / bismuth molybdenum oxide with rapid interfacial charge-transfer for dual highly efficient photocatalytic degradation and disinfection

Enhancing interfacial charge transfer is a promising approach to improve the efficiency of photocatalysts. This research effectively exploited an Ag-modified Z-scheme TiO2/Bi2MoO6 heterojunction for photocatalytic degradation and disinfection under visible light. The catalyst was fabricated using simple hydrothermal and photo-deposition methods, and the characterization outcomes revealed that a built-in electric field (BIEF) was generated in the TiO2/Bi2MoO6 heterojunctions, which significantly promotes the separation of photogenerated carriers and increases light absorption efficiency. Besides, the theoretical calculation demonstrated that electron migration between TiO2 and Ag resulted in a strong coupling on the surface, which serves as the foundation for driving photoelectric charge transfer. Furthermore, the TiO2/Bi2MoO6/Ag-45 displayed 459% and 512% higher degradation efficiency of tetracycline hydrochloride (TC-HCl) and ciprofloxacin (CIP) after 100 min compared to pristine TiO2. Moreover, the complexes wholly inactivated gram-negative Escherichia coli (E. coli) and significantly inhibited the growth of gram-positive Staphylococcus albus (S. albus) after 200 min. Additionally, we have deduced the potential degradation pathways of TC-HCl and CIP and photocatalytic mechanisms. The research results provide an idea to solve the problems of limited light absorption range and rapid carrier combination speed of traditional photocatalytic materials, which is expected to be applied in the field of actual wastewater treatment.

Self-Assembly of Bi2Sn2O7/β-Bi2O3 S-Scheme Heterostructures for Efficient Visible-Light-Driven Photocatalytic Degradation of Tetracycline

Fabrication of S-scheme heterojunctions with enhanced redox capability offers an effective approach to address environmental remediation. In this study, high-performance Bi₂Sn₂O₇/β-Bi₂O₃ S-scheme heterojunction photocatalysts were fabricated via the in situ growth of Bi₂Sn₂O₇ on β-Bi₂O₃ microspheres. The optimized Bi₂Sn₂O₇/β-Bi₂O₃ (BSO/BO-0.4) degradation efficiency for tetracycline hydrochloride was 95.5%, which was 2.68-fold higher than that of β-Bi₂O₃. This improvement originated from higher photoelectron-hole pair separation efficiency, more exposed active sites, excellent redox capacity, and efficient generation of ^·O₂ ^- and ^·OH. Additionally, Bi₂Sn₂O₇/β-Bi₂O₃ exhibited good stability against photocatalytic degradation, and the degradation efficiency remained >89.7% after five cycles. The photocatalytic mechanism of Bi₂Sn₂O₇/β-Bi₂O₃ S-scheme heterojunctions was elucidated. In this study, we design and fabricate high-performance heterojunction photocatalysts for environmental remediation using S-scheme photocatalysts.

Regulation of Structure and Anion-Exchange Performance of Layered Double Hydroxide: Function of the Metal Cation Composition of a Brucite-like Layer

As anion-exchange materials, layered double hydroxides (LDHs) have attracted increasing attention in the fields of selective adsorption and separation, controlled drug release, and environmental remediation. The metal cation composition of the laminate is the essential factor that determines the anion-exchange performance of LDHs. Herein, we review the regulating effects of the metal cation composition on the anion-exchange properties and LDH structure. Specifically, the internal factors affecting the anion-exchange performance of LDHs were analyzed and summarized. These include the intercalation driving force, interlayer domain environment, and LDH morphology, which significantly affect the anion selectivity, anion-exchange capacity, and anion arrangement. By changing the species, valence state, size, and mole ratio of the metal cations, the structural characteristics, charge density, and interlayer spacing of LDHs can be adjusted, which affect the anion-exchange performance of LDHs. The present challenges and future prospects of LDHs are also discussed. To the best of our knowledge, this is the first review to summarize the essential relationship between the metal ion composition and anion-exchange performance of laminates, providing important insights for regulating the anion-exchange performance of LDHs.

Integration of iron-manganese layered double hydroxide/tungsten carbide composite: An electrochemical tool for diphenylamine H•+ analysis in environmental samples

Incompetent governance of post-harvest horticultural crops especially apples and pears lead to numerous physiological storage disorders. In order to manage this issue, diphenylamine (DPA) is widely used as an antioxidant and anti-scald agent to preserve fruits from superficial scalds and degradation during storage. As a result, this research focuses on utilizing disposable electrodes constructed with sphere-shaped iron-manganese layered double hydroxide (FeMn-LDH) entrapped tungsten carbide (WC) nanocomposite on its electrochemical performances towards emergent food contaminant, DPA. The importance of the current work is the selection and design of hierarchically structured functional materials especially layered double hydroxides, in virtue of their outstanding properties. These multi-dimensional structures when introduced to form a composite with the highly beneficial tungsten carbide offer excellent characteristics such as exceptional accessibility to active sites, enhanced surface area, and high mass transport and diffusion which serves as advantageous for the electrochemical quantification of DPA. Furthermore, the synergy between FeMn-LDH and WC nanomaterials contributes to the higher active surface area, increased electrical conductivity, fast electron transportation, and ion diffusion, resulting in static properties including a wide linear range (0.01-183.34 μM), low detection limit (1.1 nM), greater sensitivity, selectivity, and reproducibility thus confirming the potential capability of the WC@FeMn-LDH sensor towards the interference-free determination of DPA which validates its practicality and feasibility in real-time. Hence, this work aims to stimulate the fabrication of various advanced hierarchical structures by a simple hydrothermal approach that can have veracity of potential applications.