TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: In the process: the volatile carboxylic acid is separated from the organic solvent by distillation; organic solvent obtained from the step of separating is reused in the process; the step of contacting, the organic solvent comprises an aliphatic amine having at least 10C and a phenol, a naphthol or (1-40C alkyl)phenol. In the process, the aqueous stream that is evaporated is a fermentation broth comprising a fermentation product produced by pretreating the lignocellulosic feedstock with acid or alkali to produce a pretreated feedstock composition comprising fiber solids containing cellulose, hydrolyzing the cellulose to glucose and then fermenting the glucose to produce the fermentation broth comprising the fermentation product. In the process, the aqueous stream that is evaporated is a still bottoms stream produced by pretreating the lignocellulosic feedstock with acid or alkali to produce a pretreated feedstock composition comprising fiber solids containing cellulose, hydrolyzing the cellulose to glucose, fermenting the glucose to produce a fermented solution comprising ethanol and distilling the fermented solution to produce concentrated ethanol and the still bottoms stream. In the process, the aqueous stream that is evaporated is a stream produced by hydrolyzing hemicellulose and cellulose present in the lignocellulosic feedstock with acid or alkali. In the process: the evaporating is conducted at 40-145 degrees C (preferably 60-120 degrees C) and the evaporating is operated at atmospheric pressure, under vacuum, and/or at a pressure above atmospheric pressure; the extracting is conducted at 60-175 degrees C (preferably 60-130 degrees C) and the extracting is operated at atmospheric pressure, under vacuum, and/or at a pressure above atmospheric pressure. In the process, the volatile carboxylic acid that is recovered is acetic acid. In the process, in the step of contacting, water is insoluble in the organic solvent. In the process, the volatile carboxylic acid that is present in the aqueous stream fed to the evaporating step is at a concentration of less than 5 wt.%. Preferred Components: The alkylphenol is nonylphenol or octylphenol. The aliphatic amine is tributylamine, tripentylamine, trihexylamine, trioctylamine and/or tridecylamine. The lignocellulosic feedstock is maize stover, soybean stover, maize cobs, rice straw, rice hulls, switch grass, maize fiber, wheat straw, barley straw, canola straw, oat straw and/or oat hulls. EXAMPLE - Feed flask, containing an aqueous 3.4% (34.14 g/l) acetic acid solution (50 ml), and the scrubber flask containing scrubbing solution (organic solvent, which was a 30:70 mixture of Alamine 336 (RTM: Tri-octyl/decyl amine) and nonylphenol) (50 ml), were heated in a 140 degrees C oil bath. Simultaneously, the collection flask was cooled to 0 degrees C in an ice-water bath. With heating, the vapor generated in the feed flask (the feed reflux temperature is 101 degrees C) was directed through the gas inlet tube into the scrubbing solution and bubbled through it. The glass adaptor connecting the scrubber flask to the collection flask directs the vapor generated, after passing through the organic solvent, to gas inlet tube and then into the cooled collection flask where it condenses. After 75 minutes, an aqueous solution (24 ml) was recovered in the collection flask and 19 ml of liquid remained in the feed flask. The recovered aqueous solution in the collection flask contained 1.76 g/l of acetic acid. The organic solvent removed 0.78 g of acetic acid from the 24 ml recovered in the collection flask or 94.8 % of the acetic acid.