黄原胶用于大体积空腔容器静态泡沫去污初探

PRELIMINARY STUDY ON XANTHAN GUM USED FOR TANK DECONTAMINATION BY STATIC FOAM

黄原胶作为一种用途很广的生物增稠剂和发泡剂,具有抗剪切性和耐酸、耐碱和抗氧化等特点,这些特点恰好满足静态泡沫去污对增稠剂的要求。本文测量并分析了碱性体系中(Na2CO3体系)影响发泡液粘度的几种因素(搅拌速度、黄原胶浓度、碳酸钠浓度及温度);以及酸性体系中(HNO3+H3PO4体系)黄原胶浓度和发泡液放置时间对泡沫稳定性的影响;比较分析了铝片在酸性发泡液及其生成泡沫中的失重情况。试验结果表明黄原胶无论是在碱性溶液还是在酸性溶液中均具有一定的稳定性,能够满足泡沫去污的要求;其稳定性随时间推移而降低的特性有利于泡沫去污产生的二次废液的处理。黄原胶酸性发泡液能够产生稳定的泡沫,对铝片具有良好的腐蚀效果。在本实验中,当铝片处于距底端4cm高度位置时,腐蚀速率达到1.0 mg/(cm2.h)。因此,黄原胶有望作为放射性污染大体积空腔容器静态泡沫去污的增稠剂。

Xanthan gum is widely used as a biological thickening and foaming agent for its properties of anti-shearing, resistant to acid, alkaline and oxidization condition, which just meet the requirements of decontamination with static foam for thickening agent. This paper introduces the principle of determining the stability of foam with TURBISCAN LAB, analyses the influence of some factors system,such as stirring speed, xanthan gum concentration, Na2CO3 concentration and temperature on viscosity of solution in NaECO3 system; analyses the influence of xanthan gum concentration and the retaining time of foaming solution in acidic system （HNO3 ＋ H3PO4） on the stability of foam; and compares the weight loss of aluminum plate in acidic foam and foaming solution. The results indicate that xanthan gum can be used as thickening agent in solution containing NaECO3, and HNO3 respectively,and the foam produced with the acidic solution can be stable and corrode the aluminum during the first hours after foaming. The property that the solution deteriorates with time facilitates the treatment of the liquid waste arising from the foam decontamination process. Therefore, xanthan gum is a promising thickening agent for the decontamination of radioactively contaminated tank with static foam.