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The Precipitation Of Chromium by Sodium Sulfide
To precipitate harmful chromium compounds (VII) from water, sodium sulfide is widely used by industry. The carcinogenic nature of chromium compounds (VI), which are often found in industrial waste water, is well-known (Chittim & Collins, 2019). The important aspect of water treatment is precipitation reactions. This involves the addition of a chemical agent, like Na2S. It causes formation of insoluble salts or precipitates, which can be then removed from water. This equation shows the precipitation reaction between chromium (VII) nitrate and Na2S. 2Na2S+ Cr(NO3)6 2NaNO3 + Cr2S3 (1). This reaction is exothermic which means heat is released. To prevent temperature rises too fast, it is important to monitor and cool the reaction (Chittim, Collins, 2019). The Cr2S3 product is a solid that can be safely disposed off. Na2S can be used for precipitation of chromium compounds (VI). This will ensure that these harmful substances are safely and effectively removed from the environment. This helps reduce the environmental risk from chromium VI (which can lead to further pollution) being introduced. Na2S can also be used in water treatment, as it is inexpensive.
