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1140

Pure Chromium Sulfate Heptahydrate from Waste Tanning Solutions

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Last updated: 22 Jan 2023

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Abstract

  THIS work defines a method for the preparation of pure chromium sulfate heptahydrate from waste tanning solution. The waste resource contains free and soluble fats, calcium hydroxide, iron, magnesium as soluble elements together with chromium ions. The waste solution was filtered to get rid of insoluble materials. This was followed by removal of calcium, iron and magnesium by precipitation as insoluble oxalate salts using 1.3 stoichiometric ratio of oxalic acid in faint acidic medium. Soluble fats were removed by solvent extraction using 1:1 mixture of petroleum ether and isopropanol at 60°C. The remaining solution contains chromium sulfate together with minor fat impurities. Chromium was selectively precipitated as insoluble hydroxide cake at pH 8.5. Polyacrylamide (0.05%) solution helps fast agglomeration and sedimentation of Cr (OH)   3. The hydroxide was washed repeatedly with hot distilled water. The hydroxide cake was partially dehydrated prior to reaction with pure sulfuric acid to prepare pure chromium sulfate solution. Dry chromium sulfate heptahydrate salt was prepared by addition of absolute ethyl alcohol at room temperature whereby the salt is insoluble in alcohol. The influence of some parameters that affect the productivity of the method was studied.

DOI

10.21608/ejchem.2012.1140

Keywords

Chromium sulfate, Tanning waste solutions, Precipitation and Chemical techniques

Volume

55

Article Issue

2

Related Issue

280

Issue Date

2012-04-01

Receive Date

2012-04-23

Publish Date

2012-04-30

Page Start

161

Page End

178

Print ISSN

0449-2285

Online ISSN

2357-0245

Link

https://ejchem.journals.ekb.eg/article_1140.html

Detail API

https://ejchem.journals.ekb.eg/service?article_code=1140

Order

4

Type Code

292

Publication Type

Journal

Publication Title

Egyptian Journal of Chemistry

Publication Link

https://ejchem.journals.ekb.eg/

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Article

Created At

22 Jan 2023