对变色酸分光光度法分析采气污水中甲醇含量的改进

Improvement of chromotropic acid spectrophotometry for determining methanol content in gas production wastewater

目前采气污水中甲醇含量的常用测定方法包括气相色谱法、变色酸分光光度法.其中变色酸分光光度法因设备简单,操作简便,在气田现场得到广泛应用.然而该法在甲醇浓度较高时,存在测定不准确、重现性差的问题.通过对变色酸分光光度法测定甲醇含量的实验条件优化,实现了高浓度甲醇废水的准确测定.结果表明:在最佳实验条件下,甲醇质量浓度在0～150 mg.L-1范围内线性关系良好(R=0.999 6),重现性好,准确度高,加标回收率为98.60%～104.30%,对现场含醇采气污水的测定结果与气相色谱法分析结果相符,完全满足高含醇采气污水的测定要求.

At present,there are two main methods for determining methanol content in gas production wastewater,including gas chramatography and chromotropic acid spectrophotometry.The latter is now widely applied in the site because of simple equipment and easy operation.However,it would lead to fatal inaccuracy and poor reproducibility when the concentration of methanol is high.For solving those problems,the chromotropic acid spectrophotometry for determining methanol content is improved.The improved chromotropic acid spectrophotometry achieved the accurate determination of high concentration methanol in the wastewater.The test results indicated that there is a good linear relationship between methanol percentage and absorbance(r=0.999 6) under the optimum experiment conditions in the mass concentration range of 0～150 mg·L-1.The average recovery of addition standard is 98.60%～104.30%.The measured results were compared with those obtained by using gas chramatogram method,and both are consistent.Therefore,this improved method could meet with the demand of determining the content of high concentration methanol on the site.