The recovery of chromate ions from dilute solutions in low voltage electrolysis has been investigated in relation to the effects of diaphragm components and applied voltages. Mixtures of SiO
2 and Al
2O
3 powders and several kinds of porous refractory tubes were used as diaphragm materials. A netlike cathode was used in close contact with the diaphragm in order to remove the chromate ions quickly out of the cathode solution as they were formed. The chromate concentration in the cathode solution decreased logarithmically to the lower limit when the voltage of more than 6 volts was applied. The chromate ion elimination rates increased parabolically in the range of 6-20 volts but were not affected appreciably by the voltage more than 20 volts. The rates were independent of the diaphragm component in the Al
2O
3 range of 0-60% but decreased with increasing ratio of more than 60% Al
2O
3. The lower limit of chromate concentration was less than 3ppm for diaphragms consisting of less than 60% Al
2O
3 and increased with increasing Al
2O
3 content of more than 60%. Chromate ions can be thus recovered electrolytically from dilute solutions in a short time by use of the diaphragm containg more than 40% SiO
2 and in the range of 20-30 volts.
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