Aspergillus flavus is a well-known, widespread fungus that contaminates a great number of crops used for human and animal consumption, but previous study showed that camellia seed cake was not susceptible to A. flavus. This study was designed to evaluate the antifungal effect of the active substance in camellia seed cake on the growth and production of aflatoxins of A. flavus. Eighty percent methanol extracts of camellia seed cake showed greater activity than that of 80% ethanol, ethyl acetate, and pure water against A. flavus. The filtrate from the 80% methanol extract was extracted with ethyl acetate and saturated n-butanol; among the extracts, the n-butanol phase exhibited strong inhibitory activity against A. flavus. The inhibitory zone diameter increased from 15.25 mm at 25 mg/mL concentration up to 22.00 mm at 100 mg/mL concentration. The mycelial dry weight was reduced significantly from 0.16 g at 25 mg/mL to 0.11 g at 100 mg/mL, whereas the aqueous and ethyl acetate phases exhibited weak antifungal activity and no activity, respectively. In addition, the n-Butanol phase inhibited the production of aflatoxin B1 effectively, caused mycelia deformity, and reduced the production of conidia. n-Butanol extract of camellia seed cake exhibited apparent antagonistic effect on the growth and aflatoxin production of A. flavus. The concentration of 100 mg/mL worked best. This study provides a scientific basis for further study of its inhibiting mechanism.
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Ag@AgCl/GO was prepared by chemical coupling, in-situ deposition of supported AgCl, and photoreduction. The morphology, structure, and surface area of the prepared Ag@AgCl/GO were characterized by SEM, TEM, FT-IR, Raman spectra, and BET. The optical properties of the photocatalyst were analyzed by PL and UV-Vis DRS, respectively. The surface electrical properties and degradation stability were evaluated by zeta potential measurement and cyclic catalytic degradation experiments, and the photocatalytic mechanism was proposed in detail based on the ESR test and trapping experiment. The results showed that Ag@AgCl nanoparticles were spherical and cluster distributed on the folded structure of GO. The prepared Ag@AgCl/GO had good adsorption performance and photocatalytic degradation stability. The material showed good visible light catalytic performance; especially, the degradation rates of cationic dyes RhB and MB were significantly higher than those of anionic dyes MO and CR, and their degradation processes were in line with the quasi-first-order reaction kinetics. Holes (h+) and superoxide radicals (·O2-) were the main active species for the degradation of RhB.
Chemical coupling, in-situ deposition of supported AgCl, and photoreduction were used to create Ag@AgCl/CA. The morphology, structure, and surface area of the prepared Ag@AgCl/CA were characterized by SEM, TEM, FT-IR, and BET. The photogenerated electron transport efficiency and visible light absorption were analyzed by photocurrent and electrochemical impedance spectroscopy (EIS), respectively. The surface electrical properties and degradation stability were evaluated by zeta potential measurement and cyclic catalytic degradation experiments, and the photocatalytic mechanism was proposed in detail based on the ESR test and trapping experiment. The results showed that the cluster of Ag@AgCl nanoparticles were distributed on the CA crosslinking structure. The prepared Ag@ AgCl/CA photocatalytic material has a high Zeta potential, stable photocurrent, and small photogenerated electron transfer resistance. It has good adsorption and photocatalytic degradation stability for OTC. The material has a relatively strong absorption in the visible light range. Temperature and initial pH had significant effects on the degradation of OTC by photocatalytic materials. The photocatalytic degradation rate was the highest at 40°C and pH6, and the photocatalytic degradation process conformed to the quasi-first-order reaction kinetics. Holes (h+) and superoxide radicals (·O2-) were the main active species for the degradation of OTC.
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