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As a salt adsorbent, biochar could remove/isolate salt ions e.g. Na through physiochemical adsorption to mitigate the salinity of brackish water, but little is known about its magnitude and mechanisms. The current study aimed to examine the effects of biochar on: (1) Na-adsorptive capacity and mechanism and (2) Electrical Conductivity (EC) and K displacement. Six pyrolysis temperatures (250, 350, 450, 550, 650, and 750ºC) were applied to produce biochars from rice husk. The biochars were then used as adsorbents to adsorb Na from salty water varying in NaCl concentrations. The Langmuir isotherm Model (LMM) and Dubinin-Radushkevick isotherm Model (DRM) were used to quantify the dependence of adsorbed Na on Na concentration at equilibrium. The LMM quantification revealed that the maximum Na-adsorptive capacity of biochars increased from 25.8 to 67.8 (mg g^-1) upon increased temperatures. The EC was reduced and the K amount displaced from biochar was increased with an increase in pyrolysis temperature. The DRM quantification revealed that the Na-adsorptive mechanism was mainly a physical process. A significant relationship between the Na amount adsorbed and the K amount displaced from biochar suggested that the ion-exchange mechanism could co-exist. In brief, the findings indicated that the salinity of the brackish water could be significantly mitigated by the biochar treatment through mainly physical adsorption leading to a reduced EC and increased K: Na ratio.

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The widespread use of silver Nanoparticles (AgNPs) in various industries has raised concerns about the fate of these materials. Therefore, the present study aimed to assess the effects of coating agents of Ag particles in soil and how they interact with plants as the first step in the human food chain. Radish (Raphanus sativus) was exposed to silver Nitrate (AgNO₃) as well as AgNPs with different coatings: Citrate (AgNPs-Cit), Polyethyleneimine (AgNPs-PEI), and Polyvinylpyrrolidone (AgNPs-PVP) at different concentrations. The effect of concentration (5, 25, 125 mg kg^-1 soil) and the type of coatings on the dry weight of radish were compared with the control. The results revealed that the type of treatments affected dry weight of radish and, among all treatments, AgNO₃ had the highest weight loss, in which shoot dry weight decreased by 51%. Total silver measurement in radish root, tuber, and shoot indicated that the accumulation of AgNPs was influenced by the type and concentration of the coating. The AgNPs with positive charge coating (PEI) had a higher transfer ratio than other treatments. The findings indicated that radish had the ability to store silver in its root, tuber, and shoots in large amounts, thus having the potential to act as a source of silver contamination for humans.