Environmental Science and Pollution Research Pub Date : 2021-09-21 , DOI: 10.1007/s11356-021-16503-9 Nemanja Barac 1 , Ernest Barcelo 2, 3 , Dusica Stojanovic 4 , Stoja Milovanovic 4 , Petar Uskokovic 4 , Patrick Gane 2, 4 , Katarina Dimic-Misic 2 , Monireh Imani 2 , Djordje Janackovic 4
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In this work, we examine two modifications of fine-ground calcium carbonate material (GCC) in order to enhanced sorption of NO2 and subsequent reaction properties toward NO2−/NO3− formation by firstly exposing the GCC to supercritical (sc) CO2 in order to increase particle surface area, a choice specifically made to avoid altering the surface chemistry, and secondly considering the potential advantage of using a surface coupling agent toward NO2. The modification by the coupling agent amino silane (AMEO silane) was applied in a supercritical CO2–ethanol mixture. The samples were characterised before and after modification by field emission scanning electron microscopy (FESEM), specific surface area determination (BET nitrogen adsorption), ATR-FTIR spectroscopy and ion chromatography to reveal the effects of the surface modification(s) on the morphology, surface textural properties and sorption versus reaction properties with NO2. The performance of the treated sorbents for NO2 capture was evaluated at room temperature. Results show that reactivity of NO2 with GCC was observed to increase as a function of increased surface area resulting from scCO2 exposure, but that the presence of AMEO silane on the surface, while enhancing initial adsorption of NO2 was seen subsequently to act to block reactivity. Thus, judicious use of coupling agent can provide desired rapid initial adsorption of the gas, but the goal of long-term CaCO3-consuming reactivity, so as to prolong the uptake of NO2 beyond surface saturation alone, is achieved by increasing surface area while retaining chemical-free exposed CaCO3 surface.
Graphical Abstract
中文翻译：
在超临界二氧化碳-乙醇混合物下改性 CaCO3 和 CaCO3 针涂纤维素纸以增强 NO2 捕获
在这项工作中，我们检查了细磨碳酸钙材料 (GCC) 的两种改性，以通过首先将 GCC 暴露于超临界 (sc) CO来增强 NO 2的吸附和随后对 NO 2 - /NO 3 -形成的反应特性2为了增加颗粒表面积，特别做出选择以避免改变表面化学，其次考虑使用表面偶联剂对NO 2的潜在优势。偶联剂氨基硅烷（AMEO硅烷）改性应用于超临界CO 2– 乙醇混合物。通过场发射扫描电子显微镜（FESEM）、比表面积测定（BET氮吸附）、ATR-FTIR光谱和离子色谱法对改性前后的样品进行表征，以揭示表面改性对形貌的影响，表面结构特性和吸附与 NO 2的反应特性。在室温下评估处理过的吸附剂对 NO 2捕获的性能。结果表明，观察到 NO 2与 GCC 的反应性随着 scCO 2暴露导致的表面积增加而增加，但 AMEO 硅烷在表面的存在，同时增强了 NO 2的初始吸附随后被发现采取行动阻止反应性。因此，明智地使用偶联剂可以提供所需的气体快速初始吸附，但是通过增加表面积来实现长期消耗 CaCO 3的反应性的目标，从而延长 NO 2的吸收超过表面饱和度同时保留无化学物质暴露的 CaCO 3表面。
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