The organic impurities of hot galvanizing mainly come from the decomposition product of brightener. Apart from adsorption and loss of inclusions, the brightener will also decompose during electroplating. Especially when adding human oxidant (hydrogen peroxide, potassium permanganate remove iron), brightener is easy to be oxidized decomposition. When these products accumulate to a certain concentration, they will have an impact on the properties of the bath and the coating: too much organic matter in hot galvanizing prevents the brightener from functioning, the coating is not bright, and the brightener consumption increases (the obvious effect of the brightener becomes weaker). There are more organic impurities in the coating, the brittleness of the coating increases, and the corrosion resistance decreases. There is only one method to remove the organic impurities from hot galvanizing: activated carbon adsorption.

Activated carbon has grain shape and powder shape two kinds. The powder has large surface area and adsorption capacity, but the filtration is difficult. The particle size is smaller than the surface area, the adsorption amount is small, but the filtration is easy. Therefore, when activated carbon is used for adsorption, if powder is used, less amount is used (about 1-2 /L). And when using grain shape, want tower above 2~3 times dosage.

Test the activity of activated carbon before using activated carbon adsorption:

Open the activated carbon pocket and put it in the corner of the workshop. The next day, observe the activated carbon (the activated carbon at the top of the pocket) for moisture absorption. If moisture absorption, then this activated carbon can be used, otherwise can not be used.

There are two adsorption methods for activated carbon:

1) adsorb activated carbon powder on the filter core of the filter and filter the plating solution repeatedly. This method can also be used in ordinary production to remove organic decomposition products at any time, but the dosage should be less.

2) sprinkle activated carbon directly into human plating solution, stir lh vigorously and stay still overnight, and filter it the next day. It has to be filtered several times to be clean.

The plating solution treated by activated carbon will lose part of the brightener, which needs to be adjusted. The amount of the brightener is best controlled by hall tank, which can also be used for the trial production of 1-2ml /L.

Sometimes too much brightener is added before treatment, but it doesn't work. After purification, the original brightener will be released. You don't need a brightener.