^(10)BF_(3)制备H_(3)^(10)BO_(3)反应进程在线监测

On-line Monitoring of H_(3)^(10)BO_(3)Preparation from^(10)BF_(3)

工业规模生产富集^(10)B的硼酸(H_(3)^(10)BO_(3),^(10)B>19.8%)时需要监测反应的进行程度和判定反应的终点。为解决现有监测方法步骤繁琐、人为误差大、精准度低等问题,本文设计并建造了一套在线监测反应进行程度的实验装置,并采用该实验装置对通过富集^(10)B的三氟化硼(^(10)BF_(3),^(10)B>19.8%)与难溶于水的碳酸锶(SrCO_(3))反应制备H_(3)^(10)BO_(3)的实验进行原位、实时、在线监测。测试得到的溶液离子浓度随时间变化的数据曲线可以用c_(t)-c_(1)=c_(0)e^(-kt)公式进行拟合,其拟合系数R^(2)为1.00000。在相同条件下,进行了4次重复性测试实验,得到的4条溶液离子浓度随时间变化的数据曲线用c_(t)-c_(1)=c_(0)e^(-kt)公式拟合,其拟合系数R^(2)都为1.00000,说明用该实验装置进行长时间、多次测试,得到的数据精准度高、误差小、重现性好;且拟合方程的3个参数c1、c0、k的标准偏差(s)均小于0.3%,这说明用c_(t)-c_(1)=c_(0)e^(-kt)方程拟合的精密度高。c_(t)-c_(1)=c_(0)e^(-kt)方程可以用于^(10)BF_(3)制备H_(3)^(10)BO_(3)反应的进行程度监测。实验得到的离子浓度-时间曲线的拟合方程c_(t)-c_(1)=c_(0)e^(-kt)与化学反应的一级动力学方程ct=c_(0)e^(-kt)在表现形式上一致,表明用c_(t)-c_(1)=c_(0)e^(-kt)方程拟合^(10)BF_(3)制备H_(3)^(10)BO_(3)反应的进行程度符合化学反应进行实质,c_(t)-c_(1)=c_(0)e^(-kt)方程能够作为^(10)BF_(3)制备H_(3)^(10)BO_(3)反应进行程度和反应终点的判定依据。^(10)BF_(3)制备H_(3)^(10)BO_(3)较合理的加料方式是难溶固体粉末SrCO_(3)与H2O先混溶,搅拌下形成悬浮液,然后把悬浮液加热至设定温度并保持恒定,再向悬浮液中加入^(10)BF_(3)。在线监测结果表明,^(10)BF_(3)制备H_(3)^(10)BO_(3)需经过3步加羟基脱氟取代反应,其前两步反应是快反应,第3步反应是慢反应,即第3步反应是^(10)BF_(3)制备H_(3)^(10)BO_(3)反应的速率控制步骤。^(10)BF_(3)制备H_(3)^(10)BO_(3)反应为表观化学一级动力学反应。

The industrial production of H_(3)^(10)BO_(3)(^(10)B>19.8%)requires monitoring the extent of the reaction and determining the endpoint of the reaction.In order to solve the problems of complicated steps,large human error and low accuracy of the existing monitoring methods,an experimental device for on-line monitoring the progress of the reaction was designed and built,and the experiment of H_(3)^(10)BO_(3)prepared by the reaction of^(10)B-enriched boron trifluoride(^(10)BF_(3),^(10)B>19.8%)and strontium carbonate(SrCO_(3))insoluble in water(H2O)was monitored in situ,in real time and on-line by using this experimental device.The data curves of the ion concentration of the solution changing with time obtained by the test can be fitted by the formula of c_(t)-c_(1)=c_(0)e^(-kt),and the fitting coefficient R^(2)is 1.00000.Under the same conditions,four data curves of the ion concentration of the solution changing with time are fitted by the formula of c_(t)-c_(1)=c_(0)e^(-kt),and the fitting coefficient R^(2)are all equal to 1.00000.The long-term and repeated test results of this experimental device indicate that the obtained data has high accuracy,small error,and good reproducibility.The standard deviations(s)of the three parameters of c1,c0 and k of the fitting equation are all less than 0.3%,which shows that the fitting precision of c_(t)-c_(1)=c_(0)e^(-kt)equation is high.The equation of c_(t)-c_(1)=c_(0)e^(-kt)can be used to monitor the progress of the reaction of preparing H_(3)^(10)BO_(3)from^(10)BF_(3).The fitting equation c_(t)-c_(1)=c_(0)e^(-kt)of the data curve of ion concentration changing with time obtained from the experiment is consistent with the first-order kinetic equation of ct=c_(0)e^(-kt)of chemical reaction,which shows that the progress of the reaction of preparing H_(3)^(10)BO_(3)by fitting^(10)BF_(3)with c_(t)-c_(1)=c_(0)e^(-kt)equation is in line with the essence of chemical reaction,and the equation c_(t)-c_(1)=c_(0)e^(-kt)can be used as^(10)BF_(3)to prepare H_(3)^(10)BO_(3).The most reasonable feeding method for preparing H_(3)^(10)BO_(3)from^(10)BF_(3)is that insoluble solid powder SrCO_(3)and H2O are mixed and stirred to form a suspension,then the suspension is heated to a set temperature and kept constant,and then^(10)BF_(3)is added to the suspension.The on-line monitoring results show that the preparation of H_(3)^(10)BO_(3)from^(10)BF_(3)requires three steps of defluorination hydroxyl substitution reaction,in which the first two steps of defluorination hydroxyl substitution are fast reactions,and the third step of defluorination hydroxyl substitution is slow reactions,that is,the third step of hydroxyl substitution reaction is the rate control step of the preparation of H_(3)^(10)BO_(3)from^(10)BF_(3).The reaction of preparing H_(3)^(10)BO_(3)from^(10)BF_(3)is an apparent chemical first-order kinetic reaction.