岩盐矿提钾老卤中溴离子选择性电氧化过程研究

Selective electro-oxidation of bromide ion in potassium-extracted brine from rock salt mines

中南半岛岩盐矿提钾老卤中溴离子含量约为3000 mg/L,是极具价值的制溴原料。岩盐矿伴生溴资源的有效利用,对提高岩盐矿资源综合利用价值,缓解我国溴资源短缺现状,具有经济、社会及环境多重意义。通过三电极体系线性扫描伏安法与电氧化实验,对含溴模拟卤水中溴离子的氧化速率以及氯离子浓度、电极的有效面积、搅拌速率对其的影响进行研究。结果表明1.150 V为合适的溴离子选择性氧化的电极电位,且反应符合一级反应动力学规律。针对氯离子浓度为280 g/L的岩盐矿提钾老卤,石墨电极的有效面积50.18 cm^(2),搅拌速率400 r/min时溴离子电氧化的速率最快,反应速率常数为0.3042 h^(-1),电氧化8 h后溴转化率为91.9%。

The bromide ion content in the potassium-extracted old brine from the Indo-China Peninsula rock salt mine is about 3000 mg/L,which is a valuable raw material for bromine production.The effective utilization of associated bromine resources in rock salt mines provides a number of significant economic,social,and environmental benefits,which will improve the comprehensive utilization value of rock salt mine resources and alleviate the shortage of bromine resources in our country.In this work,a three-electrode system was designed in which the anode was graphite electrode,the cathode was platinum sheet electrode,and the reference was Ag/AgCl electrode.Firstly,the suitable potential for selective electro-oxidation of Br-in the potassium-extracted brine from rock salt mines was determined by linear sweep voltammetry(LSV)method.Then,the kinetic and the expression of the oxidation rate of the electro-oxidation of Br-in bromine-containing simulated brine under this potential condition were explored through the electro-oxidation experiments in the three-electrode system.Finally,the influence of Cl-concentration,effective electrode area and stirring rate on the oxidation rate of Br-in brominecontaining simulated brine was investigated,and the optimal operating conditions were obtained.The results show that 1.150 V is a suitable electrode potential for the selective oxidation of bromide ions,and the reaction conforms to the first-order kinetic law.For the potassium-extracted brine from the rock salt mines with the Cl-concentration of280 g/L,when the effective area of the graphite electrode is 50.18 cm^(2)and the stirring rate is 400 r/min,the fastest electro-oxidation rate of Br-was observed,the corresponding reaction rate constant is 0.3042 h^(-1),and about 91.9%of Br-was converted after 8 h of electro-oxidation.These results validate the feasibility of the selective oxidation of bromine in potassium-extracted brine from the rock salt mines by electro-oxidation.