GB / T 12496.19-1999 wooden activated carbon -- Determination of iron content

1. principle

Ammonia persulfate was used as oxidant, ammonia thiocyanate as developer, Fe3 + and ammonia thiocyanate formed red complex, which was determined by visual method.

2. steps

A. reagent

① Hydrochloric acid "1 + 9" solution;

② Ammonia persulfate, 10g / L ammonia persulfate solution;

③ Ammonia thiocyanate, 10g / L ammonia thiocyanate solution;

④ 0.01mg/ml iron standard solution.

b. Operation method

① Weigh 1.00G (accurate to 10mg) of dry sample crushed to 71um and place it in a 100ml conical flask;

② Add 25ml of "1 + 9" hydrochloric acid solution and simmer for 5min‘

③ After a little cold, filter it into a 50ml colorimetric tube, wash the filter residue several times with hot water, and combine the filtrate and washing solution into the colorimetric tube;

④ Add 5ml of ammonia persulfate solution to the colorimetric tube, then add 5ml of ammonia thiocyanate solution, dilute to the scale with distilled water, shake well, and place for 10min. At the same time, treat the standard sample according to the above steps, and compare the red color with the standard solution.