Chromate Reduction By the Flow Method A glass column (ht. 50 em, dia 2.5 em) was packed with 25 g of granulated slag (2-4 mm) from a steel plant. While packing, the same weight (25 g) of glass beads was ~ added to the slag to facilitate a convenient flow within the column. Distilled water (20 ml) was then placed in the column to s~bmerge the contents of the column. The chromate solution of known concentration and acidity was placed in a separatory funnel, and the chromate solution was allowed to flow at a rate of 4.2-5.2 ml/min. The first collection (20 ml) of the effluent which contained mostly distilled water was rejected.

1. REDUCTION OF CHROMATE
By sreeremya.s
Asst professor,sree narayana guru
college,cbe

2. • Hexavalent chromium is toxic not only to man
but
• also to fish for which 1.2 - 5.0 ppm of
chromate have
• been found to be fatal

3. • They are employed in the manufacture of
paint
• pigments, in chrome tanning, aluminium
anodizing and
• other metal cleaning, plating and
electroplating
• operations. The concentrations (mg/1) of
chromium (VI)
• have been reported to be as follows

4. • Wood
• preserving 0.23-1.5, cooling tower blow down
10-60,
• leather tanning 40, electroplating bath 15-70,
anodizing
• bath 15000-52000, dip bath 2000-75000.

5. • The amount of chromium compounds
discharged through the waste streams of
metal finishing industry is estimated to about
2.81 x 107 kg/year 8. 2 X 106 kg (as sodium
dichromate). Approximatelyof chronium (as Cr
• 2o3) are lost as waste from sodium
dichromate manufacture each year.

6. • Chromate Reduction By the Flow Method
• A glass column (ht. 50 em, dia 2.5 em) was packed
• with 25 g of granulated slag (2-4 mm) from a steel plant.
• While packing, the same weight (25 g) of glass beads was ~
• added to the slag to facilitate a convenient flow within
• the column. Distilled water (20 ml) was then placed in
• the column to s~bmerge the contents of the column. The
• chromate solution of known concentration and acidity was
• placed in a separatory funnel, and the chromate solution
• was allowed to flow at a rate of 4.2-5.2 ml/min. The
• first collection (20 ml) of the effluent which contained
• mostly distilled water was rejected.

7. • vessels, and the concentrations of chromate were
• determined titrimetrically using standard ferrous
• ammonium sulfate solution, and ferroin as
indicator. The
• experiment was repeated using different
concentrations
• of chro'~ ite solutions, each time using a freshly
packed
• column.