Photocorrosion resistant Ag2CO3@Fe2O3/TiO2-NT nanocomposite for efficient visible light photocatalytic degradation activities

Fe2O3/TiO2/reduced graphene oxide-driven recycled visible-photocatalytic Fenton reactions to mineralize organic pollutants in a wide pH range

Photocatalytic Fenton reactions combined the advantages from both photocatalysis and Fenton reaction in mineralizing organic pollutants. The key problems are the efficiency and recycling stability. Herein, we reported a novel Fe2O3/TiO2/reduced graphene oxide (FTG) nanocomposite synthesized by a facile solvothermal method. The TiO2 in FTG degraded organic pollutants and mineralized intermediates via photocatalysis under visible light irradiation, which could also promote Fenton reaction by accelerating Fe3+-Fe2+ recycle. Meanwhile, the Fe2O3 rapidly degraded organic pollutants via Fenton reactions, which also promoted photocatalysis by enhancing visible light absorbance and diminishing photoelectron-hole recombination. The high distribution of TiO2 and Fe2O3 on rGO, together with their strong interaction resulted in enhanced synergetic cooperation between photocatalysis and Fenton reactions, leading to the high mineralization efficiency of organic pollutants. More importantly, it could also inhibit the leaching of Fe species, leading to the long lifetime of FTG during photocatalytic Fenton reactions in a wide pH range from 3.4 to 9.2.

Photocatalytic Degradation of 4-tert-butylphenol Using Solar Light Responsive Ag2CO3

In this work, Ag2CO3 was prepared via a solution-based method and was further characterized by XRD, Raman spectroscopy, SEM/EDS analysis, and UV-VIS spectroscopy. SEM results revealed the formation of micro-sized particles with a rectangular shape. The photocatalytic activity of the catalyst was evaluated in the degradation of 4-tert-butylphenol (4-t-BP) under simulated solar light irradiation. The effects of 4-t-BP initial concentration (2.5–10 ppm), catalyst dosage (100–300 mg/L), different types of lamp sources, and water matrix were investigated. Complete 4-t-BP (5 ppm) degradation was achieved after 60 min by Ag2CO3 (200 mg/L). The effect of anions such as CO32−, HCO3−, NO3−, and Cl- in the concentration range of 100–300 mg/L was also studied. CO32− promoted the photocatalytic degradation process, while HCO3− and NO3− exhibited an inhibition effect, which was marked with increasing HCO3− and NO3− concentrations. The presence of Cl− at the concentration of 100 mg/L increased 4-t-BP degradation, but higher concentrations inhibited the photocatalytic reaction. Cyclic experiments showed that the catalyst practically retained its catalytic activity toward 4-t-BP degradation after three successive experimental runs.

Enhanced Photocatalytic Activity of WS2/TiO2 Nanofibers for Degradation of Phenol under Visible Light Irradiation

Binary composite WS2/TiO2 nanofibers (WTN) were elaborated by electrospinning technique. The photocatalytic efficiency of the binary nanofibers was changed via different ratios between WS2 and TiO2. The structural, morphological and optical properties of the prepared nanofibers were evaluated by Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and UV-Vis diffuse reflectance spectroscopy (UV-vis/DRS), respectively. The prepared nanofibers showed a remarkable performance in photocatalytic efficiency of phenol compound degradation under visible light. WTN nanofibers showed superior photocatalytic activity (83%) and high stability of several cycles under visible light. Therefore, WS2/TiO2 nanofibers have great prospects for the treatment of wastewater from toxic organic contamination due to their excellent photocatalytic performance reusability and recyclability.

Incorporation of a Z-scheme AgI/Ag6Si2O7 heterojunction to PET fabric for efficient and repeatable photocatalytic dye degradation

Anchoring the Z-scheme AgI/Ag6Si2O7 photocatalyst on PET fabric facilitates reuse. AgI enhances the separation effect of photogenerated carriers. The photocatalytic activity and stability of AgI/Ag6Si2O7/PET composites are greatly improved.

Hazardous waste treatment technologies

This is a review of the literature published in 2018 on topics related to hazardous waste management in water, soils, sediments, and air. The review covers treatment technologies applying physical, chemical, and biological principles for contaminated water, soils, sediments, and air. PRACTITIONER POINTS: The management of waters, wastewaters, and soils contaminated by various hazardous chemicals including inorganic (e.g., oxyanions, salts, and heavy metals), organic (e.g., halogenated, pharmaceuticals and personal care products, pesticides, and persistent organic chemicals) was reviewed according to the technology applied, namely, physical, chemical and biological methods. Physical methods for the management of hazardous wastes including adsorption, coagulation (conventional and electrochemical), sand filtration, electrosorption (or CDI), electrodialysis, electrokinetics, membrane (RO, NF, MF), photocatalysis, photoelectrochemical oxidation, sonochemical, non-thermal plasma, supercritical fluid, electrochemical oxidation, and electrochemical reduction processes were reviewed. Chemical methods including ozone-based, hydrogen peroxide-based, persulfate-based, Fenton and Fenton-like, and potassium permanganate processes for the management of hazardous were reviewed. Biological methods such as aerobic, anaerobic, bioreactor, constructed wetlands, soil bioremediation and biofilter processes for the management of hazardous wastes, in mode of consortium and pure culture were reviewed.

Magnetically separable BiOBr/Fe3O4@SiO2 for visible-light-driven photocatalytic degradation of ibuprofen: Mechanistic investigation and prototype development

The increasingly ubiquitous release of emerging refractory pollutants into water is a serious concern due to associated risks. In this study, mesoporous hierarchical BiOBr/Fe₃O₄@SiO₂-a solvothermally synthesized visible-light-driven magnetic photocatalyst-not only exhibited fast kinetics (t_1/2 = 8.7 min) in the photocatalytic degradation of ibuprofen in water but also achieved almost complete mineralization over a prolonged irradiation of 6 h. Various reactive species, including O₂¯, OH, and H₂O₂, were detected, while the scavenging experiments revealed that e_CB^--mediated reactions and direct-hole oxidation are the major degradation routes. The magnetically recycled BiOBr/Fe₃O₄@SiO₂ maintained ∼80% of its initial photocatalytic activity even after five consecutive cycles. The typically copresent wastewater constituents, including NOM and anions, inhibited the photocatalytic performance to varying extents, and hence necessitated an increase in the photocatalyst dosage to achieve complete ibuprofen degradation in real sewage. Based on the findings of batch experiments, the process was scaled up by developing a 5 L prototype photocatalytic reactor integrated with an electromagnetic separation unit. The results of prototype photocatalytic experiments were comparable to those of batch experiments, and an electromagnetic separation efficiency of ∼99% was achievable in 5 min.

Engineering nanomaterials for water and wastewater treatment: review of classifications, properties and applications

Based on their characteristics and applicability, a new category of NMs is proposed for water and wastewater treatment.

An ultrasonic method for the synthesis, control and optimization of CdS/TiO2 core–shell nanocomposites

In this study, an ultrasonic method was utilized in combination with microemulsion to synthesize CdS/TiO₂ core–shell nanoparticles and control their particle size and ultimately optimize the influential parameters. Moreover, response surface methodology (RSM) was used to optimize the thickness of the shell. Herein, four parameters, i.e. temperature (67–79 °C), synthesis retention time (45–105 min), TiO₂ : CdS ratio (1.5–7.5) and the power of ultrasound waves (37–53 watt), were optimized to synthesize nanoparticles with an average size of up to 10 nm. A correlation equation was introduced for the size range of 10–90 nm, which was then proven to have excellent predictions. To verify the proposed model, two different sets of combinations were selected to synthesize 10 nm composites, and consequently, nanocomposites with the sizes of 10.4 and 10.9 nm were successfully synthesized. The power of ultrasound waves and retention time had the most influence on the size of the particles. Further experiments proved that the optical absorption spectrum of the composite particles was extended to the visible region. Furthermore, the formation of CdS/TiO₂ core–shell nanocomposites was confirmed by different characterization techniques including XRD, TEM, EDAX, UV-vis, FTIR and DLS.

In this study, an ultrasonic method was utilized in combination with microemulsion to synthesize CdS/TiO₂ core–shell nanoparticles and control their particle size and ultimately optimize the influential parameters.