折光法在线测定混合溶剂中丙酮

Online determination of acetone in mixed solvents by refractometry

建立在线折光法快速测定混合溶剂中丙酮浓度的方法。采用MSDR-SH 70系列防爆浓度传感器,以折射率为检测信号,在线检测丙酮-植物油抽提溶剂混合溶剂中丙酮浓度,同时研究了混合溶剂中姜精油含量、含水率高低对溶剂折光率波动的影响。实际生产中引入的姜精油含量、含水量对实际控制的混合溶剂折射率影响不大。通过测定不同浓度丙酮-植物油抽提混合溶剂在20~50℃范围内的折射率,利用最小二乘法原理和python编程建立了浓度、温度和折射率之间的关系曲线和经验公式(n=1.37732-0.00014φ-0.00036t)。自制11批样品重复测量5次的相对标准偏差均不大于2.2%,说明该方法检测精密度良好;与理论值相比,测定值的相对偏差均不大于5.0%,说明该方法准确度较高。在线取样检测值与气相色谱法检测值对比,绝对误差不大于2%,可满足车间实际生产过程控制需要。

An on-line refraction method for rapid determination of acetone concentration in mixed solvent was established.MSDR-SH 70 series explosion-proof concentration sensors were used to detect the concentration of acetone in the mixed solvent of acetone-vegetable oil extraction solvent with refractive index as the detection signal.The influence of the content of ginger essential oil and moisture content in the mixed solvent on the fluctuation of refractive index was also studied.It was found that the essential oil and water content introduced in the actual production had little influence on the refractive index of the actual controlled mixed solvent.By measuring the refractive index of acetone-vegetable oil extraction mixed solvents with different concentrations at temperatures ranging from 20 to 50°C,a relationship curve and empirical formula(n=1.37732-0.00014φ-0.00036t)between concentration,temperature,and refractive index were established using the least squares method and python programming.The relative standard deviation of 11 batches of self�made samples measured for 5 times was less than 2.2%,indicating that the detection precision of this method was good.Compared with the theoretical values,the relative deviations of the measured values were less than 5.0%,indicating that the method was highly accurate.The absolute error was less than 2%when comparing the value of online sampling with that of gas chromatography,which could meet the need of actual production process control in the workshop.