A green approach to DDT degradation and metabolite monitoring in water comparing the hydrodechlorination efficiency of Pd, Au-on-Pd and Cu-on-Pd nanoparticle catalysis

Meta-analysis of metal nanoparticles degrading pesticides: what parameters are relevant?

The rise in the global population demands an increasing food supply and methods to boost agricultural production. Pesticides are necessary for agricultural production models, avoiding losses of close to 40%. Nevertheless, the extensive use of pesticides can cause their accumulation in the environment, causing problems for human health, biota, and ecosystems. Thus, new technologies have emerged to remove these wastes efficiently. In recent years, metal and metal oxide nanoparticles (MNPs) have been reported as promising catalysts to degrade pesticides; however, a systematic understanding of their effect on pesticide degradation is still required. Therefore, this study focused on a meta-analysis of articles available in Elsevier's Scopus and Thomas Reuters Web of Science, found by searching for "nanoparticle pesticide" and "pesticide contamination." After passing different filters, the meta-analysis was performed with 408 observations from 94 reviews, which comprise insecticides, herbicides, and fungicides, including organophosphates, organochlorines, carbamates, triazines, and neonicotinoids. Herein, 14 different MNPs (Ag, Ni, Pd, Co₃O₄, BiOBr, Au, ZnO, Fe, TiO₂, Cu, WO₃, ZnS, SnO₂, and Fe⁰), improved pesticide degradation, with the highest degradation rates achieved by Ag (85%) and Ni (82.5%). Additionally, the impact of the MNP functionalization, size, and concentration on pesticide degradation was quantified and compared. In general, the degradation rate increased when the MNPs were functionalized (~ 70%) compared to naked (~ 49%). Also, the particle size significantly affected the degradation of pesticides. To our knowledge, this study is the first meta-analysis performed about the impact of MNPs on pesticide degradation, providing an essential scientific basis for future studies.

Synthesis of Pd-CoxOy Hybrid Nanostructure-Encapsulated Hollow Silica Nanospheres through Reverse Microemulsion Systems and Their Application as Efficient Hydrodechlorination Catalysts

Pd-Co_xO_y heteroaggregate-encapsulated hollow porous silica nanoreactors (Pd-Co_xO_y@HPSNs) were synthesized by a reverse microemulsion system. The key design of the developed reverse microemulsion system is to use poly(ethyleneimine) in the water droplets as the void templates for silica deposition and for anchoring the catalytic functionality inside the hollow silica nanospheres. The synthesized Pd-Co_xO_y@HPSNs contain ∼3 nm Pd-Co_xO_y hybrid nanostructures in ∼10 nm central cavities of silica nanospheres and illustrated a significantly promoted efficiency for hydrodechlorination of a series of chlorophenols into phenols under mild reaction conditions. The catalytic enhancement of Pd-Co_xO_y@HPSNs is ascribed to the synergistic effect between Pd and Co_xO_y and the protection of silica shells to the inner catalytic functionality.