Treatment of the butadiene washing stream from a synthetic rubber industry and recovery of p-TBC.
Butadiene is marketed containing p-tertbutylcatechol (p-TBC), a polymerization inhibitor that should be removed before butadiene utilization in synthetic rubber production. p-TBC can be removed from butadiene by washing with sodium hydroxide (NaOH) solution, producing a wastewater with pH 14, which contains high amounts of p-TBC, a toxic chemical compound. The aim of this work was to develop a treatment process that could reduce the content of p-TBC from the wastewater. Since p-TBC is very soluble in basic, but not in neutral and acid solutions, acidification tests were performed with phosphoric acid (H3PO4) to precipitate p-TBC. Reaction between NaOH and H3PO4 can result in crystallization of large amounts of salt without p-TBC precipitation. Under selected acidifying conditions p-TBC precipitates and the wastewater COD is highly reduced (> 90/o). Chromatographic determinations showed that the precipitated p-TBC could be recovered with 99% purity.
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Chemical Engineering Program (COPPE), Federal University of Rio de Janeiro, PO Box 68502, 21941-972 Rio de Janeiro RJ, Brazil.
Azevedo
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Dezotti
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D002070:Butadienes / Q000737:chemistry*; D002396:Catechols / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification*; D011232:Chemical Precipitation; D020724:Elastomers / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D010756:Phosphoric Acids / Q000737:chemistry; D012972:Sodium Hydroxide / Q000737:chemistry
D002070:Butadienes; D002396:Catechols; D020724:Elastomers; D007220:Industrial Waste; D010756:Phosphoric Acids; D012972:Sodium Hydroxide; C015047:p-tert-butyl catechol; C030242:phosphoric acid