高盐废水中硅的形态定性识别及定量分析

Qualitative identification and quantitative analysis of the form of silicon in high-salt wastewater

在工业高盐废水的排放处理过程中,废水中存在的硅元素会导致硅垢产生,产生的硅垢质地坚硬,很难清洗,严重影响废水处理效率及系统运行。为提高废水处理过程中的除硅效率,优化除硅工艺流程,需要对高盐废水中硅元素的存在形态及含量进行测试,选择合适的除硅方法及除硅药剂。分别使用硅钼黄分光光度法和硅钼蓝分光光度法对某水处理脱盐段反渗透浓盐水中的硅含量进行测试,并对两方法进行精密度分析,结果表明,当测定硅含量小于5 mg/L的水样时,硅钼蓝分光光度法的精确度略高于硅钼黄分光光度法。当测定硅含量大于50 mg/L的水样时,硅钼黄分光光度法的精确度明显高于硅钼蓝分光光度法,方法RSD小于1%,并且硅钼黄法更为简便。选用硅钼黄分光光度法进行硅元素形态的定性识别及定量分析,测试结果表明,全硅含量为138.82 mg/L,活性硅含量为79.89 mg/L。并把高盐废水中硅元素的存在形态分为3种,即Si_(a)(单硅酸和二聚硅酸)、Si_(b)(低聚硅酸)、Si_(c)(高聚硅酸及非活性硅),含量分别为72.57 mg/L、7.32 mg/L、58.93 mg/L。

In the process of the discharge of industrial high-salt wastewater,the silicon element in the wastewater will result in the production of silica scale.And difficulty of removing silica scale seriously affects the efficiency of wastewater treatment and the operation of the system.In order to improve the efficiency of silicon removal in the wastewater treatment process and optimize the silicon removal process,it is necessary to test the presence state and content of silicon in high-salt wastewater,and choose appropriate silicon removal methods and silicon removal agents.Silicon-molybdenum yellow spectrophotometry and silicon-molybdenum blue spectrophotometry were used to test the silicon content in reverse osmosis concentrated brine in a water treatment desalination section,and the precision analysis of the two methods showed that when the silicon content of water samples was less than 5 mg/L,the precision of the silicon-molybdenum blue spectrophotometry is slightly higher than that of the silicon-molybdenum yellow spectrophotometry.When the silicon content of water samples was more than 50 mg/L,the precision of the silicon-molybdenum yellow spectrophotometry is obviously higher than that of the silicon-molybdenum blue spectrophotometry,the relative standard deviation is less than 1%,and this method is more convenient.The silicon-molybdenum yellow spectrophotometric method is used for the qualitative identification and quantitative analysis of silicon form.And the results indicated that the total silicon content was 138.82 mg/L and the active silicon content was 79.89 mg/L.And the existence of silicon in high-salt wastewater was divided into three types,namely Si_(a)(monosilicic acid and dimeric silicic acid),Si_(b)(oligosilicic acid),and Si_(c)(high-polysilicic acid and inactive silicon),whose contents were 72.57 mg/L,7.32 mg/L,and 58.93 mg/L,respectively.