Photocatalytic degradation of chlorpyrifos using Ag nanoparticles-doped g-C3N5 decorated with dendritic CdS

Nature-inspired polymer photocatalysts for green NADH regeneration and nitroarene transformation

Photocatalysis has emerged as a promising approach for generating solar chemical and organic transformations under the solar light spectrum, employing polymer photocatalysts. In this study, our aim is to achieve the regeneration of NADH and fixation of nitroarene compounds, which hold significant importance in various fields such as pharmaceuticals, biology, and chemistry. The development of an in-situ nature-inspired artificial photosynthetic pathway represents a challenging task, as it involves harnessing solar energy for efficient solar chemical production and organic transformation. In this work, we have successfully synthesized a novel artificial photosynthetic polymer, named TFc photocatalyst, through the Friedel-Crafts alkylation reaction between triptycene (T) and a ferrocene motif (Fc). The TFC photocatalyst is a promising material with excellent optical properties, an appropriate band gap, and the ability to facilitate the regeneration of NADH and the fixation of nitroarene compounds through photocatalysis. These characteristics are necessary for several applications, including organic synthesis and environmental remediation. Our research provides a significant step forward in establishing a reliable pathway for the regeneration and fixation of solar chemicals and organic compounds under the solar light spectrum.

Theoretical insights into the HO●-induced oxidation of chlorpyrifos pesticide: Mechanism, kinetics, ecotoxicity, and cholinesterase inhibition of degradants

The oxidation of the common pesticide chlorpyrifos (CPF) initiated by HO● radical and the risks of its degradation products were studied in the gaseous and aqueous phases via computational approaches. Oxidation mechanisms were investigated, including H-, Cl-, CH3- abstraction, HO●-addition, and single electron transfer. In both phases, HO●-addition at the C of the pyridyl ring is the most energetically favorable and spontaneous reaction, followed by H-abstraction reactions at methylene groups (i.e., at H19/H21 in the gas phase and H22/H28 in water). In contrast, other abstractions and electron transfer reactions are unfavorable. However, regarding the kinetics, the significant contribution to the oxidation of CPF is made from H-abstraction channels, mostly at the hydrogens of the methylene groups. CPF can be decomposed in a short time (5-8 h) in the gas phase, and it is more persistent in natural water with a lifetime between 24 days and 66 years, depending on the temperature and HO● concentration. Subsequent oxidation of the essential radical products with other oxidizing reagents, i.e., HO●, NO2●, NO●, and 3O2, gave primary neutral products P1-P15. Acute and chronic toxicity calculations estimate very toxic levels for CPF and two degradation products, P7w and P12w, in aquatic systems. The neurotoxicity of these products was investigated by docking and molecular dynamics. P7w and P12w show the most significant binding scores with acetylcholinesterases, while P8w and P13w are with butyrylcholinesterase enzyme. Finally, molecular dynamics illustrate stable interactions between CPF degradants and cholinesterase enzyme over a 100 ns time frame and determine P7w as the riskiest degradant to the neural developmental system.

The Catalytic Role of Superparamagnetic Iron Oxide Nanoparticles as a Support Material for TiO2 and ZnO on Chlorpyrifos Photodegradation in an Aqueous Solution

Chlorpyrifos (CP) is a globally used pesticide with acute toxicity. This work studied the photocatalytic degradation of CP using TiO2, ZnO nanoparticles, and nanocomposites of TiO2 and ZnO supported on SPIONs (SPION@SiO2@TiO2 and SPION@SiO2@ZnO). The nanocomposites were synthesized by multi-step incipient wetness impregnation. The effects of the initial pH, catalyst type, and dose were evaluated. The nanocomposites of SPION@SiO2@TiO2 and SPION@SiO2@ZnO showed higher CP photodegradation levels than free nanoparticles, reaching 95.6% and 82.3%, respectively, at pH 7. The findings indicate that iron oxide, as a support material for TiO2 and ZnO, extended absorption edges and delayed the electron-hole recombination of the nanocomposites, improving their photocatalytic efficiency. At the same time, these nanocomposites, especially SPION@SiO2@TiO2, showed efficient degradation of 3,5,6-trichloropyridinol (TCP), one of the final metabolites of CP. The stability and reuse of this nanocomposite were also evaluated, with 74.6% efficiency found after six cycles. Therefore, this nanomaterial represents an eco-friendly, reusable, and effective alternative for the degradation of chlorpyrifos in wastewater treatment.