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Recovery of Chromium from the waste water of Leather Industry

Author: Moghira Badar* , M.K. Qamar* and M. Saleem Akhtar**

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Abstract

The Recovery of chromium from tannery wastewater is attractive not only environmentally but also economically. Chromium III containing wastewaters were oxidized independently in alkaline conditions with three aqueous oxidants i.e. Magnesium Oxide, Sodium Hypochlorite and Calcium Hypochlorite to soluble chromate. Magnesium Oxide was potentially a suitable oxidant as it could oxidize a suspension of Cr(OH)3 to chromate to 98.5% (synthetic solution) and 88.3% (waste water). The percentage recoveries by the hypochlorites were lower than those by Magnesium Oxide. For all three oxidants complete recovery could not be achieved despite different experimental conditions (temperatures and oxidation time). The amount of chromate recovered was determined by spectrophotometry. The results clearly indicate that Magnesium Oxide is the most efficient among the three oxidants.

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Conclusion

The recovery using Magnesium Oxide (MgO) is economical, environment friendly and simple. The cost expended on the recovery of chromate from a 1L 100mg/L Cr III synthetic solution showed that the value for MgO is 19 times lower than that for NaOCl and 8 times lower than that for Ca(OCl)2. Badar, Qamar and Akhtar 55 In tanneries the concentration of chromium (tanning drum) after chrome tanning may range from 3000-6000 mg/L depending on the size of the drum. The drum normally used in small and medium size tanneries are of 8 feet diameter and 8 feet in length. Therefore, we can estimate the amount of water in a drum and in turn the amount oxidant plus alkali required for the recovery. The recovered chromate can be reused in the in the tanning process in various proportions. Besides the recovered chromate can be converted to other useful products such as lead and barium chromates, dichromate, chromic oxide, chromium sulphate, etc.

References

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How to cite this article

Moghira Badar , M.K. Qamar and M. Saleem Akhtar (2017). Recovery of Chromium from the waste water of Leather Industry , Biological Forum – An International Journal 9(1): 52-55.