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Abstract
Preventing environmental contamination and avoiding economic loss, mass transfer parameters effective kinetic mass transfer coefficient (β) and effective intraparticle diffusivity (Def ) have been determined for designing the recovery of ammonium nitrate from caustic condensate (waste of granular fertilizers production: (NH 3 0.211 to 0,003 mol-1 and NH 4 NO 3 0 to 0.214 mol-1, pH of 11.1 to 5.3), using sulphonic cation exchangers Purolite C 160 MBH (macroporous) and Purolite SGC 100x10 MBH (gel). On decreasing the concentration of ammonia in influent and increasing that of ammonium nitrate instead, and subsequently, decreasing the pH, the β value, characterizing mass transfer in the liquid film surrounding the bead, for Purolite C 160 MBH (resistant to shrinking and swelling) increases from 2.4 10-2 to 8.7 10-2 s-1, whereas the Def value varies from 0.18 10-10 to 0.11 10-10 m2 s-1. For Purolite SGC 100x10 MBH (shrinking in alkaline and swelling in acidic medium) β varies from 1.8 10-2 to 2.8 10-2 s-1, although Def increases from 0.1 10-10 to 0.34 10-10 m2 s-1, whereas uptake by both cation exchangers decreases. Inside the beads of Purolite SGC 100x10 MBH the diffusion is hindered by shrinking in alkaline medium and promoted by swelling in acidic medium. For Purolite C 160 MBH breakpoint is later, capacity at breakthrough (Eb ), capacity at exhaustion (Ee ) and efficiency of utilization (λ) are higher than those for Purolite SGC 100x10 MBH. On the basis of parameters considered Purolite C 160 MBH has been installed for the recovery of ammonium nitrate from caustic condensate in fertilizer production.