Ammonium Chloride Production and Optimization of Brine Ammoniation for Lime Removal in Leather Processing
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Date
2014-06
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Addis Ababa University
Abstract
Leather industry occupies a place of prominence in Ethiopian economy in view of its massive potential for employment, growth and export. The need of import substituting leather processing chemicals from locally available feed stocks is an urgent matter both from economic and environmental point of view. One of the chemicals used in leather processing is ammonium chloride which is a deliming agent in Beam house operation. In this study, the production of ammonium chloride from proven available urea feed stocks ammonia, carbon dioxide and from the cheapest chlorine source sodium chloride which is readily available in Ethiopia, and its use and efficiency as a deliming chemical as compared to standard ammonium chloride is analyzed. A modified Solvay process approach was adopted in search of a route to the production of ammonium chloride locally. The method involves brine purification, ammoniated brine formation, carbonation of ammoniated brine, separation of sodium bicarbonate from ammonium chloride containing mother liquor, evaporation of ammonium chloride filtrate, cooling of the evaporated ammonium chloride filtrate to crystallize, centrifugation and drying of ammonium chloride which is collected as a white solid crystal of 98.5 - 99.5 wt.% NH4Cl. This preparation met the established specification for ammonium chloride of Indian Society for Testing and Materials (ISTM). The maximum yield of ammonium chloride (92.5%) was produced when the brine ammoniation reaction was carried out at a temperature of 100C, ammonium solution to saturated brine molar ratio of 2 and reaction time of 1 hour. Therefore, these values can be considered as optimal for ammonium chloride production using ammonium solution, dry ice and saturated brine in batch reactor. The reaction temperature was varied in the range of 100C - 200C, ammonium solution to saturated brine molar ratio was varied in the range of 1 – 3; and reaction time was varied in the range of 0.5 - 1.5 hours. Testing of the optimal product on leather met the IULTCS standards.
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Process Engineering