Identification of soil-specific aging processes of EINP

整个研究小组第二阶段要解决的主要过程是纳米颗粒的反应，掩蔽和捕获以及这些过程对其流动性和生态毒理学的影响。我们的项目SOILMOBILE II将重点关注那些被确定为控制这些过程的关键土壤条件（溶液中阳离子的浓度和价态，DOM的质量和浓度，EINP的浓度，土壤颗粒的比表面积）。详细地，我们将测试以下假设：掩蔽和溶解。Ag EINP的溶解受矿物-有机涂层、多价阳离子和聚集控制。有机涂层通过降低EINP表面对氧化剂的可及性来降低Ag 0 EINP的溶解度。有机涂层的这种效果随着有机物质的分子尺寸的增加和/或随着有机物质和Ag之间的阳离子桥的增加而增加（与MASK和PORESURFACE合作）。我们将使用等温纳米量热法研究（i）从各种土壤样品中提取的DOM化合物（<100 kDa，>100 kDa）和（ii）两种模型有机分子（聚半乳糖醛酸，柠檬酸盐）在不同阳离子浓度和价态下对Ag 0 EINPs的吸附。DOM涂层将与MASK合作进行分析。此外，我们将确定涂层和电解质对Ag 0 NPs的溶解动力学的影响（使用我们实验室最近开发的微透析技术）。捕获：土壤材料对EINP（Ag，Au，TiO 2）的保留是由（a）运输到多孔土壤矿物而不是（B）与土壤颗粒的静电相互作用控制的。在接近自然的土壤条件下，稳定EINP的均匀聚集和过滤与吸附和渗透到土壤团聚体中的相关性较小。(a)添加到干燥土壤材料中的EINP可以通过质量流被输送到土壤的微团聚体中。我们将分析土壤微团聚体的大小和孔隙体积特征的保留。将分析土壤团聚体对EINP保持的可逆性。此外，我们将使用薄切片和SEM/EDX分析（与PORENET合作）绘制EINP的空间分布图。(b)我们将量化EINP的吸附作为其大小和表面电荷的函数。此外，还将使用ITC分析吸附热，以确定土壤颗粒对EINP的截留机制（与PORENET、PORESURFACE合作）。

Main processes to be addressed in the second phase of the whole research group are reaction, masking and catching of nanoparticles as well as the consequences of these processes on their mobility and ecotoxicology. Our project SOILMOBILE II will have a focus on those soil conditions which are identified as crucial for controlling these processes (concentration and valency of cations in solution, quality and concentration of DOM, concentration of EINP, specific surface of soil particles). In detail we will test the following hypotheses:Masking and dissolution. The dissolution of Ag EINP is controlled by mineral-organic coatings, by multivalent cations and by aggregation. Organic coatings decrease the solubility of the Ag0 EINP by decreasing the accessibility of EINP surfaces for oxidizing reagents. This effect of organic coatings increases with increasing molecular size of the organic matter and/or with increasing cation bridges between organic matter and Ag (cooperation with MASK and PORESURFACE). We will study the adsorption of (i) DOM compounds (<100 kDa, >100 kDa) extracted from various soil samples and (ii) two model organic molecules (polygalacturonic acid, citrate) to Ag0 EINPs at varying cation concentration and valency using isothermal nano-calorimetry. DOM coatings will be analyzed in cooperation with MASK. Furthermore, we will determine the effects of coatings and electrolytes on the dissolution kinetics of Ag0 NPs (using a micro-dialysis technique which is recently developed in our lab).Catching: The retention of EINP (Ag, Au, TiO2) by soil material is controlled by (a) transport into porous soil minerals rather than by (b) electrostatic interactions with soil particles. Under close-tonatural soil conditions homo-aggregation and filtration of stabilized EINP is of minor relevance compared to adsorption and penetration into soil aggregates.(a) EINP added to dry soil material may be transported via mass flow into the micro-aggregates of the soil. We will analyse the retention by soil micro-aggregates characterised for size and pore volume. The reversibility of EINP retention by soil aggregates will be analysed. In addition, we will map the spatial distribution of EINP using thin sections and SEM/EDX analyses (cooperation with PORENET).(b) We will quantify the adsorption of EINP as a function of their size and surface charge. In addition the heat of adsorption will be analyzed using ITC to identify the mechanism of EINP retention by soil particles (cooperation with PORENET, PORESURFACE).