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%). Chromatographic determinations showed that the precipitated p-TBC could be recovered with 99% purity.
Treatment of the butadiene washing stream from a synthetic rubber industry and recovery of p-TBC
C.F. Loss, E.B. Azevedo, M. Dezotti; Treatment of the butadiene washing stream from a synthetic rubber industry and recovery of p-TBC. Water Sci Technol 1 November 2006; 54 (10): 17–21. doi: https://doi.org/10.2166/wst.2006.885
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