Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA 19104, USA.
Water Res. 2010 Jun;44(12):3659-68. doi: 10.1016/j.watres.2010.04.024. Epub 2010 Apr 29.
The effect of underwater pulsed spark discharge on the precipitation of dissolved calcium ions was investigated in the present study. Water samples with different calcium hardness were prepared by continuous evaporation of tap water using a laboratory cooling tower. It was shown that the concentration of calcium ions dropped by 20-26% after 10-min plasma treatment, comparing with no drop for untreated cases. A laser particle counting method demonstrated that the total number of solid particles suspended in water increased by over 100% after the plasma treatment. The morphology and the crystal form of the particles were identified by both scanning electron microscopy and X-ray diffraction. Calcite with rhombohedron morphology was observed for plasma treated cases, comparing with the round structure observed for no-treatment cases. It was hypothesized that the main mechanisms for the plasma-assisted calcium carbonate precipitation might include electrolysis, local heating in the vicinity of plasma channel and a high electric field at the tip of plasma streamers, inducing structural changes in the electric double layer of hydrated ions.
本研究考察了水下脉冲火花放电对溶解钙离子沉淀的影响。通过实验室冷却塔连续蒸发自来水制备了不同钙硬度的水样。结果表明，等离子体处理 10 分钟后，钙离子浓度下降了 20-26%，而未处理的水样则没有下降。激光颗粒计数法表明，等离子体处理后水中悬浮的固体颗粒总数增加了 100%以上。通过扫描电子显微镜和 X 射线衍射对颗粒的形态和晶体形式进行了鉴定。等离子体处理后的方解石呈菱面体形态，而未处理的则呈圆形结构。据推测，等离子体辅助碳酸钙沉淀的主要机制可能包括电解、等离子体通道附近的局部加热以及等离子体射流尖端的高电场，这导致水合离子双电层的结构发生变化。
