Preparation of Cu2O@TiOF2/TiO2and its photocatalytic degradation of tetracycline hydrochloride wastewater

Monitoring Ti3C2Tx MXene Degradation Pathways Using Raman Spectroscopy

Extending applications of Ti3C2Tx MXene in nanocomposites and across fields of electronics, energy storage, energy conversion, and sensor technologies necessitates simple and efficient analytical methods. Raman spectroscopy is a critical tool for assessing MXene composites; however, high laser powers and temperatures can lead to the materials' deterioration during the analysis. Therefore, an in-depth understanding of MXene photothermal degradation and changes in its oxidation state is required, but no systematic studies have been reported. The primary aim of this study was to investigate the degradation of the MXene lattice through Raman spectroscopic analysis. Distinct spectral markers were related to structural alterations within the Ti3C2Tx material after subjecting it to thermal- and laser-induced degradation. During the degradation processes, spectral markers were revealed for several specific steps: a decrease in the number of interlayer water molecules, a decrease in the number of -OH groups, formation of C-C bonds, oxidation of the lattice, and formation of TiO2 nanoparticles (first anatase, followed by rutile). By tracking of position shifts and intensity changes for Ti3C2Tx, the spectral markers that signify the initiation of each step were found. This spectroscopic approach enhances our understanding of the degradation pathways of MXene, and facilitating enhanced and dependable integration of these materials into devices for diverse applications, from energy storage to sensors.

Photocatalytic degradation of tetracycline antibiotic and organic dyes using biogenic synthesized CuO/Fe2O3 nanocomposite: pathways and mechanism insights

Tetracycline (TC) is a frequently administered antibiotic in many countries, due to its low price and excellent potency. However, certain antibiotics can be hazardous to living creatures due to their accumulation by complexation with metal ions which can contribute to teratogenicity and carcinogenicity. In this investigation, copper oxide-ferric oxide nanocomposite (CuO/Fe₂O₃ nanocomposite) was synthesized employing Psidium guajava (P. guajava) leaf extract as a reductant as well as a capping agent in an environment friendly and economical green synthesis method. The as-synthesized CuO/Fe₂O₃ nanocomposite was comprehensively characterized using various sophisticated techniques and its efficiency as a photocatalyst for degradation of tetracycline (TC) antibiotic and toxic dyes, i.e., rhodamine B (RhB) and methylene blue (MB) were investigated. The CuO/Fe₂O₃ nanocomposite exhibited exceptional efficiency for degradation of TC antibiotic (88% removal in 80 min), RhB (96% removal in 40 min), and MB (93% elimination in 40 min) with apparent rate constant of 0.048, 0.068, and 0.032 min^-1, respectively. In the degradation experiments, photocatalytic activity of CuO/Fe₂O₃ nanocomposite was studied by varying different factors such as time of contact, catalyst dose, and solution pH. The role of reactive species in antibiotics and dye degradation was validated by radical scavenging studies which indicated that^.OH radical played a critical role in photocatalytic decomposition. Furthermore, liquid chromatography-mass spectrometry (LC-MS) investigations were employed to anticipate a plausible mechanism for TC degradation.

Construction of an S-scheme TiOF2/HTiOF3 heterostructures with abundant OVs and OH groups: Performance, kinetics and mechanism insight

Developing efficient photocatalysts is of crucial significance for the development of photocatalysis techniques. In this work, an S-scheme alkaline-washed TiOF₂/HTiOF₃(OHTOF) heterostructures with abundant Oxygen vacancies (Ovs) and OH groups was successfully constructed and used to remedy antibiotic wastewater under simulated sunlight. The generation of HTiOF₃ was induced by g-C₃N₄ regulation. The results displayed that OHTOF15 composite possessed the best photocatalytic performance, which could degrade 94.2% tetracyclinehydrochloride (TCH) at a rate speed constant of 1.077 min^-1 in 2.5 h. The after-alkali-washing process increased the concentration of OH groups and Ovs defects, and greatly enlarged the surface area. The abundant Ovs and OH groups were conducive to the formation of free radicals' and the transport of charge carriers. Compared with the pristine TiOF₂, the absorption sidebands of OHTOF series were greatly red-shifted, which indicated that the increase of OH groups and the etching of the morphology of OHTOF further enhanced its visible-light harvesting ability. Furthermore, the metal cycle of the variable state of Ti⁴⁺/Ti³⁺ in OHTOF15 compensated for the charge balance and promoted the efficient separation of the carriers. Additionally, the apparent quantum efficiency (AQE) of the TCH photodegradation system based on Chemical Oxygen Demand (COD) removal efficiency was calculated to be 0.32%. It was confirmed that the electron transport path in TiOF₂/HTiOF₃ nanocomposites system followed the S-scheme type, which increased the charge carriers' separation rate and maintained a strong redox capacity. This work could provide some enlightenment for the construction of the semiconducting heterojunction and controllable surface defects engineering.

Treatment of high-concentration phosphorus wastewater based on foamed concrete

Phosphorus is a nonrenewable resource, and the recovery of phosphorus from wastewater containing high concentrations of phosphorus is of great importance. In this work, a novel method for highly efficient treatment of high-concentration phosphorus-containing wastewater (50 mg/L, 100 mg/L and 150 mg/L) with low energy consumption was developed by using the block waste foam concrete (FC) as a potential phosphorus recovery material. The results showed that acid leaching significantly improved the accumulation efficiency of phosphorus in calcium hydroxyphosphate (HAP) via accelerating the release of calcium in wastewater. The recovery rate of phosphorus could reach 99.0% under the pH value of 9.0 at 25 °C, using 2.0 g FC. It was also found that the microporous structure of the surface of FC provided the adsorption sites for phosphorus, resulting in the adsorption rate in different concentrations of phosphorus-containing wastewater up to 14.5%. It indicated that FC achieved the recovery of phosphorus from high-concentration phosphorus-containing wastewater by coupling HAP crystallization and physical adsorption to polyphosphorus.

Preparation of C/Ho co-doped TiO2 for enhancing the photocatalytic degradation efficiency of tetracycline hydrochloride

A new C/Ho co-doped TiO2 catalyst was synthesized with Ti3C2Tx MXene and the photocatalytic performance was found to be significantly enhanced.

Mesoporous TiO2 Implanted ZnO QDs for the Photodegradation of Tetracycline: Material Design, Structural Characterization and Photodegradation Mechanism

A sol-gel method was used to prepare a mesoporous TiO2 implanted with a ZnO quantum dot photocatalyst (TZQ) for the photodegradation of tetracycline (TC) under fluorescent light irradiation. Scanning electron microscopy (SEM) shows the presence of cavities on the photocatalyst surface due to the use of starch as a synthetic template, where the nitrogen sorption results indicate that TZQ contains mesopores with reduced size (ca. 4.3 nm) versus the pore size of the parent meso-TiO2 (ca. 7.5 nm). The addition of ZnO quantum dots (QDs) resulted in spherically-shaped binary composite particles in layers onto the surface of TiO2. The coexistence of the ZnO QDs and TiO2 phase was observed using high resolution-transmission electron microscopy (HR-TEM). The photodegradation of TC was carried out in a homemade reactor equipped with two fluorescent lights (24 W each) and within 90 min of irradiation, 94.6% of TC (40 mg L−1) was photodegraded using 250 mg L−1 of TZQ at pH 9. The major reactive oxygen species identified from the scavenging tests were O2●− followed by HO●. The deconvolution of the photoluminescence spectrum of TZQ indicates the presence of a strong quantum confinement effect (QCE) of the ZnO QDs, a defect related to Ti-species and oxygen. The analysis of the intermediates detected by LC-time-of-flight/mass spectrometry (LC/TOF-MS) suggest two photodegradation pathways. The pathways were validated using the Fukui function approach and the Wheland localisation approach. This simple and efficient photocatalytic technology is anticipated to benefit small-scale animal husbandries and aquaculture operators that have limited access to sustainable water treatment technology.

A three-dimensional nano-network WO3/F-TiO2-{001} heterojunction constructed with OH-TiOF2 as the precursor and its efficient degradation of methylene blue

In this study, three-dimensional nested WO₃/F-TiO₂-{001} photocatalysts with different WO₃ loadings were prepared by a hydrothermal process and used to degrade methylene blue (MB). The photocatalysts with various ratios of WO₃ to OH-TiOF₂ can be transformed into a three-dimensional network WO₃/F-TiO₂ hetero-structure with {001} surface exposure. The results showed that the composite catalyst with 5% WO₃, denoted as FWT5, had the best comprehensive degradation effect. FWT5 has a limited band gap of 2.9 eV, which can be used as an advanced photocatalyst to respond to sunlight and degrade MB. The average pore diameter of the composite catalyst is 10.3 nm, and the multi-point specific surface area is 56 m² g⁻¹. Compared with pure TiOF₂, the average pore size of the composite catalyst decreased by 8.44 nm and the specific surface area increased by 51.2 m² g⁻¹, which provides a larger contact space for the catalytic components and pollutants. Moreover, TiO₂ on the {001} surface has higher photocatalytic activity and methylene blue can be better degraded. Under the irradiation of 0.03 g FWT5 composite catalyst with a simulated solar light source for 2 h, the degradation rate of 10 mg L⁻¹ methylene blue can reach 82.9%. The trapping experiment showed that photo-generated holes were the principal functional component of WO₃/F-TiO₂-{001} photo-catalysis, which could capture OH⁻ and form hydroxyl radical (˙OH) and improved the photocatalytic degradation performance. Kinetic studies show that the photocatalytic degradation of MB fits with the quasi-first order kinetic model.

A new type of WO₃/F-TiO₂-{001} heterostructure semiconductor material with a three-dimensional network structure was successfully prepared by the hydrothermal method.

The preparation of three-dimensional flower-like TiO2/TiOF2 photocatalyst and its efficient degradation of tetracycline hydrochloride

A kind of high-efficiency photocatalyst of the three-dimensional flower-like TiO2/TiOF2 was synthesized by a one-step hydrothermal method. XRD, FE-SEM, EDS, HTEM, BET, XPS, PL, and UV-Vis-DRS were utilized to characterize the photocatalyst. The photocatalyst of TiO2/TiOF2 shows a narrow band gap of 2.8 eV. The generation of Ti3+ and an oxygen vacancy (Ov) in the photocatalyst are helpful to increase the absorption of visible light, and to inhibit faster charge recombination by capturing photogenerated carriers. Through the degradation of tetracycline hydrochloride (TCH) under simulated sunlight, the photocatalytic activity and stability of the synthesized samples were investigated. The results showed that the removal rate of tetracycline hydrochloride was 59% only in 0.5 h of dark reaction and 85% in 0.5 h of simulated sunlight. The removal efficiency of the photocatalyst for the adsorption and photocatalytic degradation of TCH is higher than that of the single TiO2, TiOF2, and Degussa P25. The synthesized three-dimensional flower-like TiO2/TiOF2 has great application potential in the treatment of antibiotic wastewater.

Self-Cleaning Polyester Fabric Prepared with TiOF2 and Hexadecyltrimethoxysilane

In this study, self-cleaning polyester (PET) fabrics were prepared using TiOF2 and hexadecyltrimethoxysilane(HDS) treatment. TiOF2 was synthesized via direct fluorination of a precursor TiO2 at various reaction temperatures. The prepared PET fabrics had superior photocatalytic self-cleaning properties compared with anatase TiO2/HDS-treated PET fabrics under UV and sunlight with 98% decomposition of methylene blue. TiOF2/HDS-treated PET fabrics also had superior superhydrophobic self-cleaning properties compared with anatase TiO2/HDS-treated PET fabrics with a 161° water contact angle and 6° roll-off angle. After the self-cleaning tests of the non-dyed TiOF2/HDS-treated PET fabrics, we prepared dyed TiOF2/HDS-treated PET fabrics to test practical aspects of the treatment method. These PET fabrics were barely stained by tomato ketchup; even when stained, they could be self-cleaned within 4 h. These results suggest that practical self-cleaning PET fabrics with superhydrophobicity and photocatalytic degradation could be prepared using TiOF2/HDS-treatment.

Preparation of F-doped H2Ti3O7-{104} nanorods with oxygen vacancies using TiOF2 as precursor and its photocatalytic degradation activity

Photocatalytic degradation is an eco-friendly and sustainable method for the treatment of water pollutants especially tetracycline hydrochloride (TCH). Herein, we developed F-doped H₂Ti₃O₇-{104} nanorods with oxygen vacancies using TiOF₂ as a precursor by simple alkali hydrothermal and ion-exchange methods. The phase structure, surface composition, optical properties, specific surface areas and charge separation were analysed by a series of measurements. The effects of KOH concentration on the structure and properties of H₂Ti₃O₇ were investigated. It is confirmed that the TiOF₂/H₂Ti₃O₇ composite can be formed in low concentration KOH solution (1 mol L⁻¹), while the H₂Ti₃O₇ single phase can be formed in high concentration KOH solution (>3 mol L⁻¹). The prepared F-doped H₂Ti₃O₇-{104} nanorods provide a high specific surface area of 457 m² g⁻¹ and a macroporous volume of 0.69 cm³ g⁻¹. The appropriate mesoporous structure of the photocatalyst makes TCH have a stronger affinity on its surface, which is more conducive to the subsequent photodegradation. Moreover, a synergistic mechanism of photosensitization and ligand–metal charge transfer (LMCT) in the photocatalytic degradation of TCH was proposed. In addition, the prepared F-doped H₂Ti₃O₇-{104} nanorods showed excellent cycle stability and resistance to light corrosion. After five cycles of photodegradation, the degradation rate of TCH was only reduced from 92% to 83%. This low-cost strategy could be used for the mass production of efficient photocatalysts, which can be used for TCH clean-up in wastewater treatment.

Efficient photocatalytic degradation of tetracycline hydrochloride by F-doped H₂Ti₃O₇-{104} nanorods.

Impact of Titanium Dioxide (TiO2) Modification on Its Application to Pollution Treatment—A Review

A high-efficiency method to deal with pollutants must be found because environmental problems are becoming more serious. Photocatalytic oxidation technology as the environmentally-friendly treatment method can completely oxidate organic pollutants into pollution-free small-molecule inorganic substances without causing secondary pollution. As a widely used photocatalyst, titanium dioxide (TiO2) can greatly improve the degradation efficiency of pollutants, but several problems are noted in its practical application. TiO2 modified by different materials has received extensive attention in the field of photocatalysis because of its excellent physical and chemical properties compared with pure TiO2. In this review, we discuss the use of different materials for TiO2 modification, highlighting recent developments in the synthesis and application of TiO2 composites using different materials. Materials discussed in the article can be divided into nonmetallic and metallic. Mechanisms of how to improve catalytic performance of TiO2 after modification are discussed, and the future development of modified TiO2 is prospected.

Transformation of novel TiOF2 nanoparticles to cluster TiO2-{001/101} and its degradation of tetracycline hydrochloride under simulated sunlight

The anatase type cluster TiO₂-{001/101} was rapidly generated by a one-step hydrothermal method. The transformation process of coral-like TiOF₂ nanoparticles to cluster TiO₂-{001/101} was investigated for the first time, and the sensitization between cluster TiO₂-{001/101} and tetracycline hydrochloride (TCH) was also discussed. The degradation rate of TCH by cluster TiO₂-{001/101} under simulated sunlight was 92.3%, and the total removal rate was 1.76 times that of P25. Besides, cluster TiO₂-{001/101} settles more easily than P25 in deionized water. The study showed that cluster TiO₂-{001/101} derived from coral-like TiOF₂ nanoparticles had a strong adsorption effect on TCH, which was attributed to the oxygen vacancy (O_v) and {001} facets of cluster TiO₂-{001/101}. The strong adsorption effect promoted the sensitization between cluster TiO₂-{001/101} and TCH, and widened the visible light absorption range of cluster TiO₂-{001/101}. In addition, the fluorescence emission spectrum showed that cluster TiO₂-{001/101} had a lower luminous intensity, which was attributed to the heterojunction formed by {001} facets and {101} facets that reduces the recombination rate of carriers. It should be noted that cluster TiO₂-{001/101} still has good degradation performance for TCH after five cycles of degradation. This study provides a new idea for the synthesis of cluster TiO₂-{001/101} with high photocatalytic performance for the treatment of TCH wastewater.

Degradation of tetracycline hydrochloride by cluster TiO₂-{001/101} under simulated sunlight.