过滤苯甲醇注射液后的滤球,用水反复冲洗,较难除尽苯甲醇,故在用洗液处理滤球时,存余的苯甲醇和重铬酸钾的洗液发生氧化还原反应,苯甲醇被重铬酸钾氧化为苯甲酸,而重铬酸钾中的铬被从Cr~(6+)还原为Cr~(3+),此时,滤球板上产生绿色斑块, Filter benzene methanol injection after the filter ball, repeated washing with water, it is more difficult to get rid of benzyl alcohol, so when the filter ball with the lotion, the remaining benzyl alcohol and potassium dichromate lotion redox reaction, benzene Methanol is oxidized by potassium dichromate to benzoic acid, while the chromium in potassium dichromate is reduced from Cr 6+ to Cr 3+. At this time, green plaques are generated on the filter plate,