Abstract
In this paper, a set of online measurement devices of multi-electrochemical sensor was investigated. Combined with industrial distributed control system, it was first applied in extracting bromine from seawater to realize the real-time adjustment of production process parameters. In the process of extracting bromine from seawater, the pH value of acidified raw brine, the addition amount of Cl2 in the oxidation stage and the addition amount of SO2 in the absorption stage are key parameters to control the whole production process. The multi-electrochemical sensor realized a rapid and high-throughput detection of the above parameters by integrating an all-solid-stage bromide ion selective electrode (Br-ISE), Eh electrode and pH electrode. The Br-ISE and the pH electrode were self-developed electrodes and the Pt electrode was Eh electrode. The pH electrode was used to control the addition amount of H2SO4 during the acidification of the brine. The Eh electrode was used to control the addition amount of Cl2 during the oxidation stage and the addition amount of SO2 during the absorption stage. The Br-ISE was used to monitor the Br− concentration change in the raw brine. Results showed the optimum range of Eh in the oxidation stage and absorption stage of brine were 950–1000 mV and 580–610 mV, respectively. The application of multi-electrochemical sensor in industrial bromine production can realize real-time control of material addition and save the cost of production.
Highlights
In this paper, a set of online measurement devices of multielectrochemical sensor was investigated
We independently developed a multielectrochemical sensor integrated with bromide ion selective electrode (Br-ISE), pH electrode and Eh electrode, which is expected to automatically control the addition of Cl2, H2SO4 and SO2
We have tested the feasibility of applying the multi-electrochemical sensor control to industrial bromine production
Summary
The brine is alkaline ( pH = 8) and Br2 and Cl2 can be hydrolysed in brine under such a condition. Hydrolysis will cause the loss of bromine in the form of HBrO and other oxides. During the brine oxidation stage, the oxidation degree of the brine determines the final bromine extraction rate. If the concentration of H+ in seawater is improved, hydrolysis of bromine can be inhibited, it is the purpose of acidification. When the pH of the brine is too low, a large amount of acid will be consumed, but the oxidation rate does not improve greatly, which will increase the cost. It is necessary to control the pH value of the oxidation liquid accurately. According to experiments reported in the open literature, the pH of the oxidized brine is usually stabilized at 3.5–4 [41]
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