Date of Award

12-1981

Degree Name

Bachelor of Science

Department

Paper Science and Engineering

Abstract

The effects of electrocoagulation as a flocculating aide for deinking was evaluated using a "homemade" electrode unit. The unit was inserted into a laboratory-size Voith-Morden forced-air flotation cell. The process of electrocoagulation involves two steps:

1. Reducing the zeta potential of the system to 0.0 mV by pH adjustment.

2. The passing of current through the stock suspension which causes the electrolysis of the water, and thus hydrogen and oxygen gas bubbles are produced. These gas bubbles collect ink particles to form solid-gas composites which can be removed more easily using flotation.

The process was evaluated on the forced-air flotation process using brightness and microscope analysis. A relationship of deinking efficiency and shive analysis was sought, but did not prove informative. The results of the microscopic analysis and brightness measurements of the electrocoagulated stock illustrated the process has a detrimental effect on forced-air flotation system. It was determined, with further investigation, that the acid pH of the system was what was causing the detrimental effects. This suggested a more in depth look at the effects of pH on deinking; however, time was not available. The process could not be carried out under alkaline conditions due to the plating of ink on the electrodes and the degradation of the aluminum under alkaline conditions.

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