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Nanozero-valent iron (NZVI) shows great potential in the remediation of water pollution, but its application is limited by its instability and tendency to aggregate. To enhance the dispersibility and antioxidant properties of NZVI, we prepared composites (SN) by wrapping NZVI with sodium alginate (SA) for the removal of Pb(II) from water. Various characterization methods such as SEM-EDS, BET, XPS, and FT-IR were used to study the structure of the materials, and the adsorption properties of Pb(II) in the materials were analyzed using adsorption kinetics and adsorption isotherm experiments. The results showed that SN had a specific surface area of 47.05 m2/g, which was significantly higher than the 7.56 m2/g of NZVI, and the surface passivation was reduced. The maximum adsorption amount of SN on Pb(II) was obtained by fitting the adsorption isotherm model at 70.92 mg/g. After five cycles of adsorption, SN exhibited a removal rate of 95.11% for Pb(II). The mechanism of Pb(II) removal by SN involved the synergistic effect of electrostatic adsorption, redox reaction, ion exchange, and coprecipitation. Notably, even after 90 days of aging, the removal rate of Pb(II) by SN remained high at 95.39%, demonstrating good reactivity. These results indicated that SN is an effective adsorbent to remove Pb(II) contamination. [ABSTRACT FROM AUTHOR]

Tetracycline (TC) is a commonly used antibiotic and enters the soil environment continuously. As humic acid (HA) is one of the most important components in soils, it is necessary to investigate the adsorption behavior of TC by HA under different conditions. In this paper, the factor of "aging" was considered. The methodology of coating CaCO3 precipitation on the surface of HA was adopted to simulate the aging process. The adsorption kinetics and isotherm demonstrated that the uptake of TC over HA was quicker with more amount than aged HA, meaning that aging affected the mass transfer of TC from the bulk solution to the outer surface of HA as well as from HA outer surface to its interior pores. To explain the effect of aging, BET was utilized to characterize the morphology of HA and aged HA. It was found that aging resulted in a decrease in specific surface area and pore size. XPS, FTIR, and 2D-COS revealed how aging influenced the chemical composition of HA. Five kinds of functional groups carried by HA contributed to the adsorption of TC, in which the binding affinity towards TC followed the order of − COO > N − H > − C − C > C − O > O − H. These results indicated that -COO was the most sensitive adsorption site. Compared to HA, the content of -COO for aged HA decreased obviously. In summary, aging affected the morphology and chemical position of HA and consequently lead to the change in adsorption kinetics and isotherm of TC. [ABSTRACT FROM AUTHOR]

A six‐week feeding trial was conducted to determine the effects of different concentrations of fucoidan (1 g/kg, 10 g/kg and 30 g/kg; w/w) from Undaria pinnatifida on gibel carp (Carassius auratus gibelio). Our results demonstrated that 30 g/kg fucoidan significantly increased (p <.05) growth performance, intestinal digestive enzyme activities, acid phosphatase activity and immunoglobulin M content. Histological examinations revealed that gibel carp receiving 30 g/kg fucoidan had significant higher abundance of mucin‐containing goblet cells in middle and distal intestine as compared with control treatment (p <.05). Intestinal microbiota analysis showed that 30 g/kg fucoidan supplementation significantly increased (p <.05) the abundance of Cetobacterium and Aeromonas, but lowered (p <.05) the prevalence of pathogenic bacteria Plesiomonas and a mucin‐degrading bacterium Mucinivorans. Furthermore, RNA‐seq and RT‐qPCR analysis indicated that 30 g/kg fucoidan caused significant changes (p <.05) in the expression of genes involved in immune regulation (such as interleukin‐8 and cyclooxygenase), signal transduction (such as phosphatidylinositol‐4,5‐bisphosphate 3‐kinase and protein kinase B) and nutrition utilization (maltase–glucoamylase and muscarinic acetylcholine receptor 3). Together, the current study shows that fucoidan supplementation could elevate the activity of intestinal digestive enzymes, modulate intestinal microbial communities and potentiate a higher state of immune readiness, which might consequently improve growth performance and intestine health status of gibel carp. [ABSTRACT FROM AUTHOR]