Abstract: A method and apparatus for contacting and reacting fine cellulosic material with acid to produce partly-hydrolyzed cellulose, in which the cellulose is compressed to form higher density material, resulting in reduced consumption of acid and increased uniformity of reaction times. Cellulosic material, such as ground wood pulp, is compressed to reduce the interstitial spaces therein. The compressed material is contacted with an acid, such as sulfuric acid, which is allowed to wick into the interstitial spaces and react with the cellulose to produce partly-hydrolyzed cellulose.

Abstract: A method of recovering purified partly-hydrolyzed cellulose particles from a composition comprising agglomerated partly-hydrolyzed cellulose particles and an acid, using electrodialysis. The invention addresses the problem of reducing the acid to very low levels while avoiding the high capital and operating costs, high water usage and large filtration surface area or dilution time requirements of the prior art processes. Following dilution, concentration by centrifuging or settling, and/or dialysis of the composition, the composition is treated in an electrodialysis cell to remove ions, such as free sulfate from sulfuric acid. The method may include having an anion exchange resin in the feed compartment of the electrodialysis cell, adding a base to the receiving solution in the electrodialysis cell, and a second step of electrodialysis of the purified partly-hydrolyzed cellulose particles.

Abstract: A method of recovering purified partly-hydrolyzed cellulose (36) from a composition (14) comprising partly-hydrolyzed cellulose and an acid, such as sulfuric acid. A base (28) having a cation that forms a precipitate with the anion of the acid is added to the composition. For example, a base such as barium hydroxide is added to form a sulfate precipitate. The precipitate (38) is then separated from the partly-hydrolyzed cellulose (36), thus reducing its acid content. The method may include additional steps of centrifugation (18) of the composition, breaking-up agglomerations (44) in the composition after precipitation, and dialysis (42).

Abstract: A method of recovering purified partly-hydrolyzed cellulose particles from a composition comprising agglomerated partly-hydrolyzed cellulose particles and an acid, using electrodialysis. The invention addresses the problem of reducing the acid to very low levels while avoiding the high capital and operating costs, high water usage and large filtration surface area or dilution time requirements of the prior art processes. Following dilution, concentration by centrifuging or settling, and/or dialysis of the composition, the composition is treated in an electrodialysis cell to remove ions, such as free sulfate from sulfuric acid. The method may include having an anion exchange resin in the feed compartment of the electrodialysis cell, adding a base to the receiving solution in the electrodialysis cell, and a second step of electrodialysis of the purified partly-hydrolyzed cellulose particles.

Abstract: A method and apparatus for contacting and reacting fine cellulosic material with acid to produce partly-hydrolyzed cellulose, in which the cellulose is compressed to form higher density material, resulting in reduced consumption of acid and increased uniformity of reaction times. Cellulosic material, such as ground wood pulp, is compressed to reduce the interstitial spaces therein. The compressed material is contacted with an acid, such as sulfuric acid, which is allowed to wick into the interstitial spaces and react with the cellulose to produce partly-hydrolyzed cellulose.

Abstract: A method of recovering purified partly-hydrolyzed cellulose (36) from a composition (14) comprising partly-hydrolyzed cellulose and an acid, such as sulfuric acid. A base (28) having a cation that forms a precipitate with the anion of the acid is added to the composition. For example, a base such as barium hydroxide is added to form a sulfate precipitate. The precipitate (38) is then separated from the partly-hydrolyzed cellulose (36), thus reducing its acid content. The method may include additional steps of centrifugation (18) of the composition, breaking-up agglomerations (44) in the composition after precipitation, and dialysis (42).