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Biosynthetic of silver nanoparticles (AgNPs) by using fungi has attracted much attention due to its high catalytic efficiency and environmentally friendly characteristic. However, a few studies have focused on the ecological toxicity effects of biogenic AgNPs on algae. Here, we first investigated the catalytic reduction of 4-nitrophenol (4-NP) by WZ07-AgNPs biosynthesized by Letendraea sp. WZ07. WZ07-AgNPs had significant catalytic activity with 97.08% degradation of 4-NP in 3.5 min. Then, the toxic effects of WZ07-AgNPs and commercial-AgNPs were compared by Chlorella pyrenoidosa growth, chlorophyll content, protein content, physiological, and biochemical indexes. The results demonstrated that the algal cell biomass of C. pyrenoidosa was differentially inhibited after exposure to different concentrations of AgNPs, which showed concentration dependence and time dependence. The 96h-EC 50 values of WZ07-AgNPs and commercial-AgNPs on C. pyrenoidosa were 15.99 mg/mL and 12.69 mg/mL, respectively. With the increase concentration of AgNPs, the chlorophyll content was gradually decreased, the protein content was first increased and then decreased, the activities of superoxide dismutase (SOD) and catalase (CAT) were decreased, and the level of malondialdehyde (MDA) was increased significantly of C. pyrenoidosa . In general, AgNPs affect the growth of algae to some extent. However, compared with commercial-AgNPs, WZ07-AgNPs is less toxic to C. pyrenoidosa , which could be used as a potential and an eco-friendly catalyst. This study provides a basis for the safe application of biosynthetic AgNPs.

Efficient waste management, especially in relation to swaste reuse, has become a pressing societal issue. The waste bittern generated during salt production and discarded oyster shells present formidable environmental challenges and a waste of resources for some coastal regions. Therefore, this work developed a two-stage circular process for the environmentally friendly and efficient utilization of both waste materials. In the first stage, CO2 gas and an organic extraction phase comprising Tri(octyl-decyl)amine (R3N) and isoamyl alcohol were introduced into the waste bittern to obtain MgCO3·3H2O (s). The second stage involved reacting the reacted organic extraction phase with oyster shell powders to produce CaCl2·2H2O (s) and CO2 (g) and regenerate R3N. This work focused on investigating the yield of MgCO3·3H2O and the regeneration ratio of R3N, which are crucial indicators for the two stages involved in the process. The results indicate that, under optimal operating conditions, a maximum yield of 87% for MgCO3·3H2O was achieved, and the regeneration ratio of R3N reached 97%. Furthermore, the reaction mechanism and thermodynamic functions of the R3N regeneration process were elucidated as a crucial element in achieving a circular process. The findings of this work offer a sustainable solution to environmental pollution from waste bittern and oyster shells, and provide a promising avenue for green chemical production.

The oil content of tobacco leaves is intimately associated with their aromatic characteristics. This study aims to explore the microstructure and distinctive flavor substances of Yunyan 87 high-oil-content tobacco leaves. The microstructure and characteristic flavor substances of Yunyan 87 tobacco leaves with different oil contents were analyzed using scanning electron microscope (SEM) and comprehensive two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOF MS). The results indicate that the surface of high-oil tobacco leaves was characterized by a high density of glandular hairs, primarily composed of short-stalked glandular hairs featuring enlarged glandular heads. A total of 1551 flavor substances were detected in high-oil tobacco leaves, compared to 1500 metabolites were identified in low-oil tobacco leaves. Among these flavor substances, eight exhibited up-regulated, while three were down-regulated. Notably, the oil-related substances hexadecanoic acid methyl ester and the aroma-related substances nonanoic acid methyl ester and pseudoionone were found to be significantly more abundant in high-oil tobacco leaves compared to their low-oil counterparts. Consequently, hexadecanoic acid methyl ester may serve as a reliable indicator for evaluating the oil content in tobacco leaves, while nonanoic acid methyl ester and pseudoionone could play crucial roles as flavor substances influencing the aroma of tobacco leaves. These findings provide a theoretical foundation for future research on the regulatory mechanisms underlying the synthesis of aroma-producing flavor substances in tobacco leaves.