Is there still excess hydrogen peroxide in the plating solution of the electric heating tube

Is there still excess hydrogen peroxide in the plating solution of the electric heating tube

When using activated carbon to treat the plating solution, attention should be paid to the quality of the activated carbon to prevent impurities from entering the plating solution. If activated carbon contains zinc impurities, treating the nickel plating solution will cause the nickel layer to turn black or show streaks. In addition, when filtering to remove activated carbon from the plating solution, it is necessary to filter it thoroughly to prevent small particles of activated carbon from entering the plating solution through the filter element, causing rough, dark, pinhole or orange peel like coatings to appear during electroplating.

Sometimes, in order to better remove organic impurities, before using activated carbon for treatment, an oxidant (hydrogen peroxide or potassium permanganate) is used for oxidation treatment, which is called a combination treatment of oxidant and activated carbon. The commonly used method is hydrogen peroxide activated carbon treatment. When performing this operation, it is necessary to remove the excess hydrogen peroxide before adding activated carbon. Otherwise, hydrogen peroxide is an oxidant and activated carbon has reducibility, leading to an oxidation-reduction reaction (2H202+C=2H2O+C02 ↑) between each other; In addition, due to the decomposition of hydrogen peroxide into 02, it will block the fine pores of activated carbon with adsorption capacity, reducing the adsorption capacity of activated carbon. It is best to check whether there is still excess hydrogen peroxide in the plating solution before adding activated carbon. The inspection method is as follows:

(1) Dissolve 5g of KI in 100mL of water, add 5g of soluble starch, and heat until dissolved;

(2) Suck a drop of plating solution onto clean filter paper:

(3) Drop two drops of potassium iodide and starch solution onto the filter paper where the plating solution has been applied;

(4) Observation of color: If blue appears within 5 seconds, it indicates the presence of excess hydrogen peroxide (potassium iodide starch solution is unstable, and it is best to prepare and use it immediately).

The adsorption process of activated carbon is relatively fast, and most organic impurities are adsorbed within a few minutes of initial contact. Therefore, prolonged stirring during treatment is unnecessary, usually only continuous stirring for about 30 minutes is sufficient.

The activated carbon adsorption method can be applied to almost all plating solutions except for those with strong oxidizing properties that cannot be used.

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