Process for producing peracids from aliphatic hydroxy carboxylic acids

Claim 1

In a wood pulp processing system of the type producing both pulp and a stream of lactic acid-containing black liquor solution, the processor for production of peracid bleaching agents from hydroxy acid contained in the black liquor solution, comprising: adjusting the pH of said black liquor solution to the range of about 8-9 by exposing the solution to CO 2 carbon dioxide to form an alkaline precipitate; separating solids from the black liquor solution to produce a residual solution containing lower aliphatic hydroxy acids selected from the group consisting of lactic acid, glycolic acid, 2-hydroxybutanoic acid, xyloisosaccharinic acid, and glucoisosaccharinic acid; decarboxylating said lower aliphatic hydroxy acids to corresponding gaseous aliphatic aldehydes by admixing a powdered semiconductor with said residual solution to form a slurry, said semiconductor being selected from the group consisting of doped n-TiO 2 , both platinized and unplatinized, n-WO 3 , a-Fe 2 O 3 and other insoluble semiconductors having bandgaps equal to or higher than a-Fe 2 O 3 , and then irradiating said slurry by a means for causing photoelectro-chemical reaction at the site of the semiconductor material resulting in decarboxylation of the carboxylic acid and produuction of CO 2 and corresponding aldehydes; removing said gaseous aldehydes from the residual solution by sweeping gas flow as soon as they are generated to prevent further oxidation to carboxylic acids; reacting said gaseous aldehydes with oxygen to form corresponding peracids; and applying said peracids as bleaching agents to said pulp produced in the pulp processing system.