Electrokinetic removal of Ca(NO3)2 from bricks to avoid salt induced decay
Electrokinetic removal of Ca(NO3)2 from bricks to avoid salt induced decay
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电动去除砖中的 Ca(NO3)2 以避免盐引起的腐烂
DOI：
10.1016/j.electacta.2006.03.118
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Inge Rörig
中科院分区：
文献类型：
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作者：
L. Ottosen;Inge Rörig
盐引起的砖石结构的腐烂是对我们文化遗产的严重威胁。在农业用地或马厩附近的建筑物中，砌体可能会受到硝酸盐引起的盐腐蚀的严重影响。在实验室条件下，用单块砖研究了外加电场电迁移去除Ca（NO3）2的可行性。为了将获得的硝酸盐浓度与盐致衰变的危险性联系起来，将浓度与奥地利ÖNORM B 3355-1的值进行了比较。它被证明是可能的，甚至从砖中去除硝酸盐的初始浓度范围内没有危险的盐引起的衰变，这表明该方法可以达到足够低的浓度。它还表明，硝酸盐浓度可以从一个范围内减少，其中盐引起的衰变可以预期的范围内没有风险，虽然实验应该进行更长的时间，以获得这个低浓度的所有通过砖。还进行了钙去除。与硝酸盐相反，钙被吸附在砖内部表面的可交换部位，由于轻微的碱性孔隙溶液，也可能发生沉淀。在实验过程中也除去了钙，但实验装置没有成功地防止酸从阳极前面的砖表面上下来。结果发现，砖本身具有对酸化的缓冲能力，并且参与缓冲反应的可能是钙的释放。应避免砖与酸接触。观察到砖内液体的电渗运输的趋势。与阴极单元中相比，阳极单元中的液体体积不断减少。
Salt-induced decay of masonry is a serious threat to our cultural heritage. In buildings near agricultural land or stables the masonry may suffer seriously from salt-induced decay from nitrates. It was investigated in laboratory scale with a single brick if Ca(NO3)2could be removed by electromigration in an applied electric field. To relate the obtained nitrate concentrations to the danger for salt-induced decay the concentrations were compared with values from the Austrian ÖNORM B 3355-1. It was shown possible to even remove nitrate from bricks with initial concentrations in the range of no danger for salt-induced decay and this shows that the method can reach sufficiently low concentrations. It was also shown that the nitrate concentration could be reduced from a range where salt-induced decay can be expected to the range where there is no risk, though the experiments should proceed longer to obtain this low concentration all through the brick. Calcium removal was followed as well. On the contrary to nitrate, calcium was seen adsorbed in exchangeable sites to the internal brick surfaces and precipitation may also occur due to slight alkaline pore solution. Calcium was also removed during the experiments but the experimental setup did not successfully prevent acid from the brick surface in front of the anode. It was found that the brick itself had a buffering capacity against acidification, and involved in the buffering reaction may have been a release of calcium. This contact with acid to the brick should be avoided. A tendency for electroosmotic transport of liquid within the brick was seen. The volume of liquid in the anode unit was constantly decreased compared to in the cathode unit.