Studies often neglect the different trends between enantiomers in soil chiral contaminants. In the present study, paclobutrazol was chosen as the target analyte and the selective degradation patterns of this chiral pesticide were investigated in soils. After 14 days of culture, the degradation kinetics results demonstrated the degradation process of the two enantiomers conforms to first-order degradation kinetics equation, and the degradation rates were significantly different (paired t-test, P < 0.05). The degradation rate of (2S,3S)-paclobutrazol (S-paclobutrazol) was higher than that of (2R,3R)-paclobutrazol (R-paclobutrazol), with the concentration decrease of 42.6 and 28.7%, respectively. Meanwhile, the enantiomer fraction (EF) was 0.43 at final sampling point, and the half-life (t1/2) of S-paclobutrazol and R-paclobutrazol were 17.3 and 28.9 days, which demonstrated significant enantioselective degradation. Results from this study served to enhance our understanding about the enantioselective degradation behaviors of chiral pesticides, which provided some scientific basis for the potential risk assessment of chiral pesticides in the environment.

In this study, a novel deep eutectic solvent (DES) containing choline chloride and ethylene glycol was synthesized, and the magnetic polydopamine (PDA) was modified with this deep eutectic solvent to form Fe3O4@PDA-DES. Fourier transformed infrared spectroscopy, scanning electron microscopy, and vibrating sample magnetometer were used to characterize the proposed adsorbent. Then, this magnetic material was used as an adsorbent in the magnetic solid phase extraction process for the extraction of four sulfonylurea herbicides in water samples. The main parameters relevant to this method were investigated. Under the optimum conditions, the linearity was obtained by five points in the concentration range of 1.0-200 µg L-1 and with the correlation coefficients (r) ≥ 0.9927. The enrichment factors were in a range of 495 to 615 and the relative standard deviations were less than 4.3%. The limits of detection varied from 0.0092 to 0.0113 µg L-1. The recoveries of environmental water samples were 61.9 to 100.1%, and the recoveries of drinking water samples were 71.1-101.9%. All results highlighted the excellent potential of magnetic solid phase extraction coupled with ultra-high performance liquid chromatography strategy in selective separation and extraction of sulfonylurea herbicides in water samples.

A sensitive and stable electrochemical sensor based on polyaniline/graphene-ferrocenecarboxylic acid (PANI/GR-FCA) composite film modified glass carbon electrode for determination of nitrite was presented and its morphology and structure were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray powder diffraction (XRD). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were used to investigate the electrochemical behavior of the nitrite oxidation, which exhibited an enhanced voltammetric response at the modified electrode. In the optimal condition, the oxidation of nitrite in Britton-Robinson buffer solution (BR) of pH 4.0 had the higher peak current than the bare electrode. A linear calibration curve over the concentration range 0.4-300 µmol L-1 of nitrite were obtained with a linear regression equation I (µA) = 0.1589 + 0.0020C (µmol L-1) (R = 0.9991, n = 13) and the detection limit was down to 0.02 mmol L-1 (S/N = 3). The recoveries of all determinations ranged between 96-102%. At the same time, the modified electrode showed a good long-term stability and reproducibility for determination of nitrite, as well as high selectivity.

Através da técnica de polimerização radicalar por transferência atômica (ATRP) foram preparadas novos polímeros tipo pente com molhabilidade ajustável (líquido iônico) de hexafluorfosfato poli[2-(1-butilimidazolino-3-ila)etila metacrilato (PBIMH-PF6-), a partir de um substrato bruto modificado com uma camada iniciadora composta de brometo 2-bromoisobutirila. Várias técnicas de caracterização como elipsometria, medidas de ângulo de contato estático, espectroscopia fotoeletrônica de raios X (XPS) e microscopia de força atômica (AFM) foram utilizadas para caracterizar os filmes em cada etapa de modificação da superfície. Estudos cinéticos revelaram um aumento linear na espessura do filme polimérico em função do tempo de reação, indicando que o crescimento da cadeia a partir da superfície, é um processo cujo controle apresenta características de polimerização "viva". As medidas de molhabilidade indicaram que as interações de troca iônica podem ser usadas para alterar as características da superfície de hidrofilicidade para hidrofobicidade de forma reversível. O substrato bruto obtido por ataque químico exibiu uma melhor hidrofobicidade quando comparado à superfície lisa do substrato plano modificado com as mesmas cadeias poliméricas tipo pente (líquido iônico).

Using surface initiated atom transfer radical polymerization (ATRP), novel tunable wettability polymer (ionic liquid) brushes poly[2-(1-butylimidazolium-3-yl)ethyl methacrylate hexafluorophosphate] (PBIMH-PF6-) from a rough substrate modified with an initiator layer composed of 2-bromoisobutyryl bromide was prepared. Various characterization techniques including ellipsometry, static water contact angle measurements, X-ray photoelectron spectroscopy (XPS), and atomic force microscope (AFM) were used to characterize the films for each surface modification step. Kinetic studies revealed a linear increase in polymer film thickness with reaction time, indicating that chain growth from the surface was a controlled process with a "living" characteristic. Wetting measurements indicated that ion exchanging interactions can be used to switch surface characteristics from hydrophilicity to hydrophobicity in a reversible manner. Compared with the smooth surface of the flat substrate modified with the same polymer (ionic liquid) brushes, the rough substrate by chemical etching exhibited better hydrophobicity.