Photocatalytic degradation of 2,4-dichlorophenol with V2O5-TiO2 catalysts: Effect of catalyst support and surfactant additives

Physico-chemical and biological remediation techniques for the elimination of endocrine-disrupting hazardous chemicals

Due to their widespread occurrence and detrimental effects on human health and the environment, endocrine-disrupting hazardous chemicals (EDHCs) have become a significant concern. Therefore, numerous physicochemical and biological remediation techniques have been developed to eliminate EDHCs from various environmental matrices. This review paper aims to provide a comprehensive overview of the state-of-the-art remediation techniques for eliminating EDHCs. The physicochemical methods include adsorption, membrane filtration, photocatalysis, and advanced oxidation processes. The biological methods include biodegradation, phytoremediation, and microbial fuel cells. Each technique's effectiveness, advantages, limitations, and factors affecting their performance are discussed. The review also highlights recent developments and future perspectives in EDHCs remediation. This review provides valuable insights into selecting and optimizing remediation techniques for EDHCs in different environmental matrices.

A Review on Metal Ions Modified TiO2 for Photocatalytic Degradation of Organic Pollutants

TiO2 is a semiconductor material with high chemical stability and low toxicity. It is widely used in the fields of catalysis, sensing, hydrogen production, optics and optoelectronics. However, TiO2 photocatalyst is sensitive to ultraviolet (UV) light; this is why its photocatalytic activity and quantum efficiency are reduced. To enhance the photocatalytic efficiency in the visible light range as well as to increase the number of the active sites on the crystal surface or inhibit the recombination rate of photogenerated electron–hole pairs electrons, various metal ions were used to modify TiO2. This review paper comprehensively summarizes the latest progress on the modification of TiO2 photocatalyst by a variety of metal ions. Lastly, the future prospects of the modification of TiO2 as a photocatalyst are proposed.

The study on adsorption behavior of 2,4-DCP in solution by biomass carbon modified with CTAB-KOH

In this study, rice straw was used to prepare biomass carbon, which was modified with KOH and cetyltrimethylammonium bromide (CTAB) to obtain modified biomass carbon (MBC). The biomass carbon (BC) before and after modification was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR), and the surface morphology, crystal structure and surface group characteristic BC were explored. The specific surface area and micropores of the modified biomass carbon increased significantly, the crystallinity was higher, and the pore structure was more clearly found. The adsorption performance of MBC for 2,4-dichlorophenol (2,4-DCP) was investigated. The results showed that under the best adsorption conditions ((2,4-DCP concentration (200 mg/L), MBC dosage (50 mg), pH (5.5), and loading time (60 min), temperature (room temperature)), the removal rate of 2,4-DCP was up to 42.5%, and adsorption capacity was 85.13 mg/g. The adsorption of 2,4-DCP on MBC materials was better explained by the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model. It was believed that the adsorption of 2,4-DCP by MBC was the monolayer adsorption process on the uniform surface of MBC at high concentration, and there was no interaction between the 2,4-DCP and MBC adsorbate during this process.

Rational design of 3D/2D In2O3 nanocube/ZnIn2S4 nanosheet heterojunction photocatalyst with large-area "high-speed channels" for photocatalytic oxidation of 2,4-dichlorophenol under visible light

We have rationally designed and fabricated of "face-to-face" 3D/2D In₂O₃ nanocube/ZnIn₂S₄ nanosheet heterojunction by growing ZnIn₂S₄ nanosheets on the surfaces of In₂O₃ cubes as photocatalysts for 2,4-dichlorophenol (2,4-DCP) degradation under visible light. Herein, the unique 3D/2D In₂O₃ nanocube/ZnIn₂S₄ nanosheet hierarchical structure not only exposes far more abundant heterojunction interface active sites compared to 3D/0D In₂O₃ nanocube/ZnIn₂S₄ nanoparticle, but also produces numbers of compact high-speed nanochannels in the junctions, which significantly promotes the separation and migration of photogenerated carriers. Profiting by structural and compositional advantages, the optimized 3D/2D ZnIn₂S₄-In₂O₃ photocatalyst shows excellent photocatalytic activity and stability in the degradation of 2,4-DCP, which is 1.85, 2.60, 3.02 and 3.54-fold higher than that of 3D/0D ZnIn₂S₄-In₂O₃, ZnIn₂S₄ nanosheet, ZnIn₂S₄ nanoparticle and In₂O₃, respectively. Meanwhile, the main active species (·O₂^-, ·OH and h⁺) produced in the photodegradation process were determined and the intermediates and degradation mechanism were studied in detail. Besides, the application on the removal of 2,4-DCP in natural water and actual wastewaters by 3D/2D ZnIn₂S₄-In₂O₃ also have been studied. This work provides a new strategy for efficiently optimize the advantages of binary nano-architectures to effectively degrade phenolic pollutants in the environment.

Highly efficient degradation of 2,4-dichlorophenol over CeO2/g-C3N4 composites under visible-light irradiation: Detailed reaction pathway and mechanism

Herein, we report for the first time the highly efficient degradation of 2,4-dichlorophenol (2,4-DCP) over CeO₂/g-C₃N₄ composites (xCeO/CN) prepared via wet-chemical solution method. It is shown that the resultant nanocomposites with a proper mass ratio percentage (15%) of CeO coupled exhibit greatly enhanced visible-light activity for 2,4-dichlorophenol (2,4-DCP) degradation compared to the bare g-C₃N₄. From photoluminescence (PL) and Fluorescence (FL) results, it is suggested that enhanced photo-degradation is attributed to the significantly improved charge separation and transfer as a result of the proper band alignments between g-C₃N₄ and CeO components. Further, from radical trapping experiments, it is confirmed that hydroxyl radicals (OH) are the predominant oxidants involved in the degradation of 2,4-DCP over CeO/CN composites. Furthermore, a possible reaction pathway and detailed photocatalytic mechanism for 2,4-DCP degradation is proposed mainly based on the detected liquid chromatography tandem mass spectrometry (LC-MS) intermediate products, that readily transform into CO₂ and H₂O. This work would help researchers to deeply understand the reaction mechanism of 2,4-DCP and would provide feasible routes to fabricate g-C₃N₄-based highly efficient photocatalysts for environmental remediation.

Fabrication of Surfactant-Enhanced Metal Oxides Catalyst for Catalytic Ozonation Ammonia in Water

The new surfactant-enhanced metal oxides composite catalysts have been prepared using solid state method and characterized by the N₂-adsorption-desorption, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscope (TEM), and X-ray diffraction (XRD) techniques. Catalytic activity of the synthesized powders has been investigated in the liquid-phase catalytic ozonation ammonia nitrogen (NH₄⁺) (50 mg/L). Especially, the effect of parameters such as optimum molar ratio for metal salt, NaOH and surfactants, temperature, and time of calcinations was also considered. Leveraging both high catalytic activity in NH₄⁺ degradation and more harmless selectivity for gaseous nitrogen, the CTAB/NiO catalyst is the best among 24 tested catalysts, which was generated by calcining NiCl₂·6H₂O, NaOH, and CTAB under the molar ratio 1:2.1:0.155 at 300 °C for 2 h. With CTAB/NiO, NH₄⁺ removal rate was 95.93% and gaseous nitrogen selectivity was 80.98%, under the conditions of a pH of 9, ozone flow of 12 mg/min, dosage of catalyst 1.0 g/L, reaction time 120 min, and magnetic stirring speed 600 r/min in room temperature.

Degradation and Mineralization of Benzohydroxamic Acid by Synthesized Mesoporous La/TiO₂

Rare earth element La-doped TiO₂ (La/TiO₂) was synthesized by the sol-gel method. Benzohydroxamic acid was used as the objective pollutant to investigate the photocatalytic activity of La/TiO₂. The physicochemical properties of the prepared materials were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectroscopy, specific surface area and porosity, scanning electron microscopy and transmission electron microscopy. As a result, the doping of La could inhibit the crystal growth of TiO₂, increase its specific surface area and expand its response to visible light, thus improving its photocatalytic activity. La/TiO₂ with the doping ratio of 0.75% calcined at 500 °C, showing the highest photocatalytic activity to degrade benzohydroxamic acid under the irradiation of 300 W mercury lamp. About 94.1% of benzohydroxamic acid with the original concentration at 30 mg·L^-1 was removed after 120 min in a solution of pH 4.4 with an La/TiO₂ amount of 0.5 g·L^-1. Furthermore, 88.5% of the total organic carbon was eliminated after 120 min irradiation. In addition, after four recycling runs, La/TiO₂ still kept high photocatalytic activity on the photodegradation of benzohydroxamic acid. The interfacial charge transfer processes were also hypothesized.