| 摘要 |
<p>The oxidising agent to be measured is changed by chemical action into a second oxidising agent which is more reducible. The second oxidising agent is electrolysed between two electrodes held at a low difference of potential, e.g., 0.5-0.7 volts. During periodic reversals of electrode polarity, the measured intensity of elctrolysis current is proportional to the amt. of first oxidising agent to be measured. The first oxidising agent is pref. chlorine which is changed into residual iodine by reaction with an excess of potassium iodide, the liberated iodine being electrolysed. Pref. both electrodes are made of the same metal and have equal surface areas; in partic. the electrodes are both tubular helices, one inside the other, with electrolyte flowing between them. Pref. the amt. of residual oxidising agent in the treated water is monitored continuously, results are compared with a standard value and the treatment adjusted accordingly. The installation can be calibrated after chemical titration of standard samples. The proportion of oxidising agent is continuously and automatically regulated to precisely that required for optimum treatment; a slight but not significant excess of oxidising agent can opt. be assured.</p> |
