Synchronous removal of oxytetracycline and Cr(Ⅵ) in Fenton-like photocatalysis process driven by MnFe2O4/g-C3N4: Performance and mechanisms

Enhanced photocatalytic H2 generation and Cr(VI) reduction by a sheet-on-sheet Cd(OH)2/CdS nanocomposite

The advancement of efficient photocatalysts is essential for tackling global energy and environmental issues. In this work, a unique sheet-on-sheet Cd(OH)2/CdS photocatalyst was synthesized via a facile solution strategy, demonstrating significantly improved photocatalytic performance for H2 generation and Cr(VI) reduction. The optimal 5% Cd(OH)2/CdS obtained an impressive H2 production rate of 3475 μmol g-1 h-1 under visible light, marking a 6.3 times increase compared to CdS. Additionally, the kinetics of Cr(VI) reduction were markedly accelerated, with a rate constant of 0.2803 min-1, representing a 5.7 times improvement over pure CdS. Moreover, the 2D/2D Cd(OH)2/CdS photocatalyst exhibited exceptional stability, maintaining high photocatalytic activity over multiple reaction cycles. Experimental findings and DFT calculations revealed the charge transfer mechanism between CdS nanosheets and Cd(OH)2 cocatalyst. This work provides insights into designing high-performance CdS-based nanophotocatalysts for water splitting and environmental remediation.

Construction of MoS2/g-C3N4 S-scheme heterojunction promotes plasma-photocatalytic degradation of methyl p-hydroxybenzoate: Electron transfer and adsorption reduction mechanisms

A novel method of S-scheme heterojunction photocatalyst assisted with plasma was proposed to degrade the methyl p-hydroxybenzoate (MeP) in wastewater. The two-dimensional MoS2/g-C3N4 composite was prepared by the thermal polycondensation method. The sheet-like morphologies and S-scheme heterogeneous structure were validated by XRD, XPS, EDS, FTIR, and TEM in the MoS2/g-C3N4 composite. The addition of MoS2/g-C3N4 increased the MeP degradation from 74.85% to 89.85% and the TOC removal rate from 25.16% to 40.12%. The MeP solution reduced the toxicity after treating the plasma/MoS2/g-C3N4 system. Quenching experiments and electron paramagnetic resonance (EPR) spectra showed that the UV light generated by the discharge is utilized by the catalyst, which increases the yield of O2-· and 1O2, enhancing the degradation efficiency of MeP. The absorption spectral range and electron transfer ability are improved by the interaction between MoS2 and g-C3N4. The proposed charge transfer mechanism is driven by the S-scheme heterojunction built-in electric field (IEF), thereby reducing the recombination of photogenerated electron-hole pairs. The production of free radicals is increased by the adsorption-reduction reaction on the surface of MoS2 and g-C3N4. In addition, the catalytic material has good photocatalytic performance after recycling. MoS2/g-C3N4 combined with plasma exhibits excellent photocatalytic performance and has a wide range of application prospects.

Ternary heterojunction of cross-linked benzene Polymer/Bi2MoO6-Graphene oxide catalysts promote efficient adsorption and photocatalytic removal of oxytetracycline

Antibiotics are refractory degradable organic pollutants that present a significant hazard to water environments. In this work, a ternary composite (KB/BMO-GO) comprising of graphene oxide (GO), Bi2MoO6 (BMO), and a cross-linked benzene polymer (KB) was synthesized and applied to promote the synergistic adsorption-photocatalytic degradation of the refractory pollutant, oxytetracycline (OTC). The inclusion of GO and KB in the composite enhanced the OTC adsorption performance of the catalysts, and the construction of Z-scheme heterojunction promoted the photogenerated charge separation efficiency and broadened the range of light absorption, thereby enhancing the photocatalytic performance. Moreover, we compared the performance of catalysts loaded with different mass ratios of KB (x% KB/BMO-GO). Among them, the 15 % KB/BMO-GO catalyst sample had the best OTC degradation performance. Specifically, 15 % KB/BMO-GO could adsorb 69.7 % of OTC in 30 min, reaching an OTC degradation rate of 93.3 % under visible light irradiation. h+ and 1O2 are the main active substances in the photocatalytic process. In addition, the catalysts are acid-alkali and salt-resistant, as well as good reusability. This study provides a valuable reference for the preparation of highly efficient photocatalysts for synergistic adsorption-photodegradation processes.

Magnetization and ZIF-67 modification of Aspergillus flavus biomass for tetracycline removal from aqueous solutions: A stable and efficient composite

In the present work, the biomass of Aspergillus flavus (AF) was modified using magnetic nanoparticles MnFe2O4 and metal-organic framework of ZIF-67, and its ability to remove tetracycline antibiotic (TCH) was investigated. With the help of physicochemical tests, AF biomass modification with ZIF-67 and MnFe2O4 magnetic nanoparticles was confirmed. Based on the BET value, AF-MnFe2O4-ZIF-67 (139.83 m2/g) has a higher surface value than AF (0.786 m2/g) and AF/MnFe2O4 (17.504 m2/g). Also, the magnetic saturation value revealed that the modified biomass can be isolated from the treated solution using a simple magnetic field. Maximum TCH elimination (99.04%) using AF-MnFe2O4-ZIF-67 was obtained at pH 7, adsorber mass of 1 g/L, adsorption time of 40 min, and TCH content of 10 mg/L. The thermodynamic study indicated that the TCH abatement using the desired composite is spontaneous and exothermic. The experimental results showed that the adsorption process is compatible with the pseudo-second-order kinetic and Freundlich model. The maximum adsorption capacity for AF, AF-MnFe2O4, and AF-MnFe2O4-ZIF-67 was quantified to be 9.75 mg/g, 25.59 mg/g, and 43.87 mg/g, respectively. The reusability of the desired adsorbers was examined in up to 8 steps. The outcomes showed that the adsorbers can be used several times in TCH elimination. The provided composite can remove TCH from hospital wastewater, so it can be suggested for use in water and wastewater treatment works.

Light-driven photocatalysis as an effective tool for degradation of antibiotics

Antibiotic contamination has become a severe issue and a dangerous concern to the environment because of large release of antibiotic effluent into terrestrial and aquatic ecosystems. To try and solve these issues, a plethora of research on antibiotic withdrawal has been carried out. Recently photocatalysis has received tremendous attention due to its ability to remove antibiotics from aqueous solutions in a cost-effective and environmentally friendly manner with few drawbacks compared to traditional photocatalysts. Considerable attention has been focused on developing advanced visible light-driven photocatalysts in order to address these problems. This review provides an overview of recent developments in the field of photocatalytic degradation of antibiotics, including the doping of metals and non-metals into ultraviolet light-driven photocatalysts, the formation of new semiconductor photocatalysts, the advancement of heterojunction photocatalysts, and the building of surface plasmon resonance-enhanced photocatalytic systems.