Highly efficient removal of oxytetracycline using activated magnetic MIL-101(Fe)/γ-Fe2O3 heterojunction catalyst.

A novel magnetic nanocomposite MIL-101(Fe)/γ-Fe2O3 was synthesized by hydrothermal method. The physical structure and chemical property of the as-obtained magnetic nanocomposite was characterized. The ability of MIL-101(Fe)/γ-Fe2O3 to promote photo-assisted peroxydisulfate (PDS) activation was investigated by using oxytetracycline (OTC) as the target pollutant. The results showed that the composite with a FeCl3•6H2O: γ-Fe2O3 mass ratio of 10:1 exhibited the highest degradation efficiency (up to 91.2%). Influencing factors such as pH, catalyst dosage, PDS concentration and OTC concentration on the catalytic performance of MIL-101(Fe)/γ-Fe2O3 were also investigated to determine the optimum conditions. More importantly, the MIL-101(Fe)/γ-Fe2O3 can be magnetically recovered and reused for 4 cycles. Based on radical quenching and electron spin resonance (ESR), the possible degradation mechanism of OTC in photo-assisted PDS activation (PPA) system was proposed. This research provided novel insights for the design and preparation of a new type of magnetic Fe-MOFs for environmental remediation.

Construction of Z-scheme g-C3N4 / MnO2 /GO ternary photocatalyst with enhanced photodegradation ability of tetracycline hydrochloride under visible light radiation.

A facile wet-chemical method was adopted to synthesize g-C3N4/MnO2/GO heterojunction photocatalyst for visible-light photodegradation of tetracycline hydrochloride (TC). The addition of MnO2 and GO increased the absorption of visible light and the specific surface area of the photocatalyst. The results of photoluminescence, electrochemical impedance spectroscopy, and photocurrent response indicated that CMG-10 had the lowest electron-hole recombination probability, which was beneficial for the photocatalytic reaction. The ternary photocatalyst exhibited enhanced photoelectric performance and superior photocatalytic activity with 91.4% removal of TC (10 mg/L) under a mere 60 min visible light illumination, which showed enhanced photocatalytic degradation when compared with binary (CM, 77.95%; CG, 78.83%) and single (C3N4, 55.5%; MnO2, 36.41%) photocatalysts. A pH of 6 was optimal for the CMG-10 photocatalytic degradation of TC, and the optimal photocatalyst dosage was 0.5 g/L. Common coexisting ions influenced the removal of TC by influencing the production of active species. The catalyst is stable and reusable with only a 10% reduction in removal efficiency after four cycles. According to the active species analysis, the Z-scheme mechanism was a charge transfer behavior in the composite photocatalyst, which could prevent the recombination of photogenerated carriers. This study presents a photocatalytic approach to the effective removal of TC from water bodies, which provides practical implications to advance the use of photocatalytic technology in the restoration of aqueous environmental pollution.

Degradation of oxytetracycline by magnetic MOFs heterojunction photocatalyst with persulfate: high stability and wide range.

Photocatalysis with persulfate (PS) is an effective method for the degradation of degrading organic pollutants. In this study, Fe3O4/MIL-101(Fe), a magnetic heterojunction photocatalyst, was produced using a hydrothermal method. The material coupled with PS exhibited excellent removal efficiency for oxytetracycline (OTC) (87.1%, 1 h). And it has a wide range of applications, with good removal efficiency for OTC concentrations of 30 to 70 mg/L and pH values of 3 to 9. •SO4- and •OH played a major role in the OTC removal reaction and there was an Fe(III)/Fe(II) cycle during the reaction. With excellent stability and recoverability, the OTC removal efficiency decreased by only 4.29% after four cycles, and the Fe leaching did not exceed 0.035 mg/L per cycle. This study provides significant insights into the removal of organic pollutants from water bodies.

A review of metal organic framework (MOFs)-based materials for antibiotics removal via adsorption and photocatalysis.

Antibiotic abuse has led to serious water pollution and severe harm to human health; therefore, there is an urgent need for antibiotic removal from water sources. Adsorption and photodegradation are two ideal water treatment methods because they are cheap, simple to operate, and reusable. Metal organic frameworks (MOFs) are excellent adsorbents and photocatalysts because of their high porosity, adaptability, and good crystal form. The aim of this study is to suggest ways to overcome the limitations of adsorption and photocatalysis treatment methods by reviewing previous applications of MOFs to antibiotic adsorption and photocatalysis. The different factors influencing these processes are also discussed, as well as the various adsorption and photocatalysis mechanisms. This study provides a valuable resource for researchers intending to use MOFs to remove antibiotics from water bodies.

Efficient dehydration of 6-gingerol to 6-shogaol catalyzed by an acidic ionic liquid under ultrasound irradiation.

6-Gingerol and 6-shogaol are the main bioactive compounds in ginger. Although 6-shogaol has more and better bioactivities than its precursor 6-gingerol, the low content of 6-shogaol in ginger restricts its bioactive effects in functional foods. The traditional preparation methods of 6-shogaol are defective because of the environmental hazards and low efficiency of the processes. In this study, an efficient, easy and eco-friendly dehydration conversion of 6-gingerol to 6-shogaol is presented using an acidic ionic liquid 1-butyl-3-methylimidazolium hydrosulfate ([Bmim]HSO4) under ultrasound irradiation. The key parameters, including reaction temperature, reaction time, mass ratio of catalyst to substrate and ultrasonic power in each reaction process, were investigated. The yield of 6-shogaol reached as high as 97.16% under optimized condition. The catalyst could be separated from the reaction mixture and reused five times with only a slight loss of activity.