Continuous Coating Color Preparation

Fig. 7.22 Continuous preparation of coating colors (source Metso).

Wear eye protection, laboratory coat, and nitrile rubber gloves. Prepare a 10% aqueous solution of the waste sodium chlorate. For each 10 mL of solution, slowly, and while stirring, add 44 mL of a 10% solution of sodium bisulfite (this allows about 50% excess of reducing agent). The continued presence of chlorate can be detected by adding, to 3 mL of the solution, a freshly prepared solution of potassium iodide (100 mg) in 3 mL of 3 M sulfuric acid (prepared by cautiously adding 0.5 mL of concentrated acid to 2.5 mL of cold water). An amber to brown color indicates the presence of chlorate. Add sodium bisulfite solution until the test is negative. Neutralize the acidic solution with sodium carbonate and discard into the drain with at least 50 times its volume of water.11 12... 

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