Organics in soda-anthraquinone black liquors from hot-water-extracted non-wood feedstocks

ABSTRACTThe chemical compositions of black liquors (BLs) obtained from the soda-anthraquinone (AQ) pulping of untreated and hot-water-extracted non-wood feedstocks (okra stalk, miscanthus stalk, and wheat straw) were determined. These under-utilized renewable and widely available feedstocks could provide a cheaper source for producing fiber and precursors for manufacturing green chemicals. These BLs were mainly characterized in terms of carbohydrate-derived volatile carboxylic acids (acetic and formic acids) and non-volatile carboxylic acids (hydroxy acids) as well as lignin. Additionally, in each case, the average molar mass and molar mass distribution of the dissolved lignin were measured. Results indicated typical effects of hot-water extraction; for example, in the case of hot-water-extracted feedstocks, compared to untreated feedstocks, more aliphatic carboxylic acids were formed, whereas in both cases the removal of lignin was similar. The maximum total amounts of aliphatic carboxylic acids were in ...