摘要
碳酸镁和碳酸钙一样也具有胶结作用,且镁矿强度远大于钙矿,因此研究碳酸镁固化技术具有重要意义。本文测量了巴氏芽孢杆菌在培养过程中的吸光度和脲酶活性,并计算得到单位脲酶活性;研究了尿素、氯化钠、醋酸根、Ca^2+和Mg^2+浓度对脲酶活性的影响;控制温度、pH值和离子浓度对比了钙和镁沉淀效率和不同温度不同尿素浓度下碳酸镁沉淀产率;对比研究了碳酸钙和碳酸镁沉淀下砂土固化效果。结果表明,48 h培养过程中,吸光度和脲酶活性的增长都先缓慢后迅速增长再减小最后停止,单位脲酶活性则是先增加后减小。适当增加尿素或Mg^2+浓度可增强细菌脲酶活性,氯化钠和醋酸根浓度对酶活性无明显影响,Ca^2+浓度对脲酶活性有明显抑制作用。同一温度、pH值和离子浓度条件下,碳酸镁产率明显小于碳酸钙。而在菌液中添加尿素可促进碳酸镁沉淀生成,且温度相同,尿素浓度越高,碳酸镁产率越大。菌液中添加尿素可使得碳酸镁固化砂土成型并具有一定强度,因此,该方法可解决砂土固化碳酸镁沉淀不足的问题,为后续碳酸镁固化试验奠定基础。
The magnesium carbonate has a cementing feature like calcium carbonate, and the strength of magnetite ore is much higher than that of calcium ore, so it is important to study the solidification technology of magnesium carbonate. The absorbance and urease activity of Sporosarcina pasteurii are measured in the cultural process, and the unit urease activity is calculated. The influences of various factors on the urease activity are studied. Some comparison tests on the precipitation efficiency between calcium carbonate and magnesium carbonate are conducted as well as the magnesium precipitation efficiency with various urea additions. The solidification tests on the calcium carbonate and magnesium carbonate are comparatively studied. The results show that during 48 h-culture period, the absorbance and urease activity curve both increase gradually and boom, then slow down and tend to be stable. The unit urease activity increases to the peak and then decreases. The increase of the urea concentration and magnesium ion can enhance the urease activity. The concentration of sodium chloride and acetate has little effect on it, and that of calcium ion has a significant inhibitory effect. Under the same condition, the yield of magnesium carbonate is significantly smaller than that of calcium carbonate. By adding urea to medium, the precipitation significantly increases. The higher the urea concentration, the more the magnesium carbonate gets. The sample with adding urea is solidified to own certain strength in the case of magnesium carbonate precipitation. Therefore, this method can solve the problem of insufficient magnesium precipitation and establish the foundation for the curing tests on magnesium carbonate in future.
作者
孙潇昊
缪林昌
童天志
王呈呈
SUN Xiao-hao;MIAO Lin-chang;TONG Tian-zhi;WANG Cheng-cheng(Institute of Geotechnical Engineering,Southeast University,Nanjing 210096,China)
出处
《岩土工程学报》
EI
CAS
CSCD
北大核心
2018年第7期1309-1315,共7页
Chinese Journal of Geotechnical Engineering
基金
国家自然科学基金项目(51578147,51278099)
关键词
巴氏芽孢杆菌
影响因素
碳酸钙
碳酸镁
砂土固化
Sporosarcina pasteurii
influence factor
calcium carbonate
magnesium carbonate
sand solidification