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Submitted Chris Haslego, Nov 21 2011 11:21 AM | Last updated Nov 21 2011 01:29 PM

Category:	Refining
Question:	How are the acids commonly found in petroleum streams removed?
Keywords:	acid,removal,petroleum,streams,weak,scrubbing,scrub,scrubber
Answer:	The organic acids present in petroleum distillates include carboxylic acids, naphthenic acids, and various phenols which are weak acids (e.g., phenol, cresols, xylenes, ethylphenols, and others).Intermediate streams within a petroleum refinery such as naphthas, jet fuel, and kerosene, are often scrubbed with 10-15 degree Baume aqueous solutions of sodium hydroxide (i.e., caustic) to remove sulfur compounds such as mercaptans and/or hydrogen sulfide. Sometimes, the sodium hydroxide scrubbing systems also utilize a catalyst (as in the commonly used Merox processes). The sodium hydroxide scrubbing solution would also remove some or all of the organic acids present in those intermediate distillate streams. Thus, the "spent caustic" solutions from those scrubbing systems will contain sodium sulfide, sodium mercaptides, and the sodium salts of the organic acids (i.e., sodium naphthenate, sodium phenolate, etc.).For more information, you should read "Aqueous Wastes from Petroleum and Petrochemical Plants", written by M.R. Beychok and published by John Wiley and Sons in 1967.