萃取分光光度法测定氯化钾体系中的十八胺  

Extraction Spectrophotometric Determination of Octadecylamine in Potassium Chloride

作　　者：宋忠梅 路淼 张慧芳[1] 张鹏瑞 房得珍 马亮 刘青青 于雪峰 刘海宁 叶秀深[1] 马珍 彭文博 吴志坚[1] SONG Zhong-mei;LU Miao;ZHANG Hui-fang;ZHANG Peng-rui;FANG De-zhen;MA Liang;LIU Qing-qing;YU Xue-feng;LIU Hai-ning;YE Xiu-shen;MA Zhen;PENG Wen-bo;WU Zhi-jian(Key Laboratory of Green and High-end Utilization of Salt Lake Resources,Salt Lake Resources Chemistry of Qinghai Province,Qinghai Institute of Salt Lakes,Chinese Academy of Sciences,Xining 810008,China;Salt Lake Corporation Central Research Istitute,Qinghai Salt Lake Ind ustry Co.,Ltd.,Golmud 816000,China;Department of Science and Technology Affaris,Qinghai Productivity Pro motion Center Co.,Ltd.,Xining 810008,China;School of Chemical Science,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院青海盐湖研究所,青海省盐湖资源化学重点实验室,青海西宁810008 [2]青海盐湖工业股份有限公司盐湖股份中央研究院,青海格尔木816000 [3]青海省生产力促进中心有限公司科技事务部,青海西宁810008 [4]中国科学院大学化学科学学院,北京100049

出　　处：《光谱学与光谱分析》2024年第8期2240-2249,共10页Spectroscopy and Spectral Analysis

基　　金：国家自然科学基金项目(U20A20150);青海省自然科学基金项目(2023-ZJ-940J);青海省重点研发与转化计划项目(2023-GX-103);青海省中青年科技人才托举工程(2021QHSKXRCTJ-11)资助。

摘　　要：十八胺是冷结晶-正浮选法生产氯化钾的常用捕收剂,用量显著影响浮选分离效率。由于其会吸附在氯化钾表面,不可避免地在氯化钾中残留,不利于高纯钾盐产品的开发。针对氯化钾生产过程及产品中十八胺含量测定的需求,依据十八胺和溴酚蓝通过范德华力和氢键络合的作用原理,开发了以乙酸丁酯为萃取剂、溴酚蓝钠盐为显色剂的萃取分光光度法测定氯化钾中十八胺的浓度。考察了溶液pH、十二烷基吗啉、共存盐、平衡时间、显色剂用量对十八胺浓度测量的影响。结果表明:当溶液pH从3~9逐渐增大时,十八胺与溴酚蓝的络合作用减弱且络合分子极性增大,导致吸光度降低;在pH<5时,十二烷基吗啉和溴酚蓝能形成有色络合物,当pH为6~9时萃取液吸光度值趋近于零;共存氯化钾、氯化钠、硫酸钾、氯化镁等溶液的离子强度增大,氢键作用减弱但络合分子的盐析效应增强,溶液中微量的Li^(+)、NH_(4)^(+)和B对萃取液吸光度影响不大;显色剂用量过大时,吸光度值太大且不符合朗伯-比尔定律,平衡时间影响较小。选择测定条件为:溶液的pH为6、离子强度为1 mol·L^(-1),2 mmol·L^(-1)显色剂的用量为0.50 mL,采用缓冲溶液定容至25 mL,反应5 min后加入5.00 mL乙酸丁酯萃取,待分层平衡2 min后于458 nm处测定萃取液吸光度,工作曲线为A=0.04949c+0.06624(R^(2)=0.9923,ε=1.33×10^(4) L·mol^(-1)·cm^(-1),0~10 mg·L^(-1))。该方法的相对标准偏差为0.33%~2.63%,平均相对误差为-0.90%,十八胺和十二烷基吗啉混合体系的平均相对误差为-0.25%。采用该方法测得正浮选精钾母液中十八胺含量为8.66 mg·L^(-1),加标回收率为95.5%~106%,可用于测定盐湖钾肥生产过程中十八胺的浓度。Octadecylamine is a flotation collector commonly used to produce potassium chloride by cold crystallization-positive flotation,and its dosage will significantly affect the flotation separation efficiency.In addition,octadecylamine will adsorb on the surface of potassium chloride and inevitably remain in potassium chloride products,which is inconducive to developing high-purity potassium salt products.To meet the requirement of determination of octadecamide potency in potassium chloride,an extraction spectrophotometry was developed,based on the principle of van der Waals force and hydrogen bonding between octadecylamine and bromophenol blue with butyl acetate as extractant and bromophenol blue sodium salt as chromogenic agent.The effects of solution pH,dodecyl morpholine,co-existing salt,equilibrium time,and the amount of chromogenic agent on the concentration measurement of octachylamine were investigated.The results show that when the solution pH increases from 3 to 9,the absorbance of the extract decreases because the complexation between octachylamine and bromophenol blue weakens.The polarity of the complex molecules increases.When the solution pH is less than 5,dodecyl morpholine and bromophenol blue can also form colored complexes.While pH is between 6 and 9,the absorbance tends to zero.The ionic strength of the coexisting solutions of potassium chloride,sodium chloride,potassium sulfate and magnesium chloride increases,weakening the hydrogen bonding.Still,the salting-out effect of the complex molecules is enhanced,and the trace Li^(+),NH_(4)^(+) and B in the solution have little effect on the absorbance.The absorbance does not conform to Lambert-Beer law when the amount of chromogenic agent is too large.Besides,equilibrium time has little effect on the absorbance.The determination conditions in potassium chloride solution are as follows:The solution pH is 6,the ionic strength is 1 mol·L^(-1),and the amount of 2 mmol·L^(-1) chromogenic agent is 0.5 mL.5 mL butyl acetate is added to the 25 mL aqueous soluti

关 键 词：十八胺 萃取分光光度法 氯化钾 十二烷基吗啉 盐湖 

分 类 号：O657.32[理学—分析化学]