A high efficiency bleaching method for cellulosic pulp includes: (a) providing a charge of aqueous cellulosic pulp to a bleaching vessel at a consistency of from 10% to 30% along with a peroxy bleaching agent and an alkaline agent effective to adjust pH of the charge to 9.5 to 12.5; and (b) bleaching the aqueous cellulosic pulp in the bleaching vessel while maintaining a bleaching temperature of from 110 F. (43 C.) to 135 F. (57 C.) and a pH of the charge from 9.5 to 12.5 for an extended bleaching retention time. The bleaching method is advantageously used to bleach low brightness recycle pulp, and/or as part of a multistage process with bleaching stages of lesser duration, and/or as a high peroxy efficiency, low dose bleaching process or in connection with concurrently storing and bleaching pulp.

This disclosure relates to improved products containing oxidized cellulose. This disclosure further relates to improved methods of making oxidized cellulose in multi-stage bleaching processes, including, for example, in four-stage and three-stage bleaching processes. This disclosure further relates to products made therefrom, including wipe, tissue, towel, and napkin products.

A modified kraft pulp fiber with unique properties is provided. The modified fiber can be a modified bleached kraft fiber that is almost indistinguishable from its conventional counterpart, except that it has a low degree of polymerization (DP). Methods for making the modified fiber and products made from it are also provided. The method can be a one step acidic, iron catalyzed peroxide treatment process that can be incorporated into a single stage of a multi-stage bleaching process. The products can be chemical cellulose feedstocks, microcrystalline cellulose feedstocks, fluff pulps and products made from them.

The present invention relates to a method of generating chlorine dioxide from chlorite salts in the presence of a manganese ion-containing complex, a method of treating a substrate with a chlorine-containing oxidant in the presence of a manganese ion-containing complex and related aqueous media, kits and compositions.

A method to optimize the chemical balance at a sulfate pulp mill, which produces at least pulp bleached with chlorine dioxide and has a chlorine dioxide plant using at least chlorate, methanol and sulfuric acid for making chlorine dioxide. The method includes: a) gases from the mill's concentrated non-condensable gas system are incinerated in order to form a gas containing sulfur dioxide, which is treated to produce concentrated sulfuric acid, and b) raw methanol from the mill processes is purified to produce methanol, and c) side streams containing sodium compounds and/or sulfur compounds produced by mill processes are used as make-up chemicals, wherein the production of chlorine dioxide uses the sulfuric acid produced in step a) and methanol purified in step b), with a sulfuric acid concentration of 94-99%, preferably 95-98%, and using in step c) sesquisulfate or sodium sulfate produced during the production of chlorine dioxide.

The present invention provides an enzymatic method for reducing the content of hexenuronic acids in a chemical cellulosic pulp and/or improvement of the brightness of cellulosic pulp using haloperoxidase.

A process for obtaining cellulose, hemicellulose and lignin from lignocellulose can be carried out in an environmentally friendly manner when it comprises the following steps: step a) wherein a lignocellulose from plant biomass is provided, step b) wherein the lignocellulose is brought into contact with a first mixture M1 containing water and an alkaline component, and a first suspension S1 forms, the first suspension S1 comprises a first solid F1 and a first liquid phase P1, wherein the first solid F1 contains a crude cellulose, and the first liquid phase P1 contains hemicellulose and lignin, and step c) wherein the crude-cellulose-containing solid F1 is brought into contact with a second mixture M2 containing formic acid and water and optionally acetic acid, and a second suspension S2 forms, the second suspension S2 comprises a second solid F2 and a second liquid phase P2, wherein the second solid F2 contains a pure cellulose, and the second liquid phase P2 contains hemicellulose and lignin.

Compositions including treated Kraft pulp, useful for making rayon fibers, having a lower degree of polymerization, a high R18, a low hemicellulose content, and high reactivity, are described. Methods of making the compositions are also described.

A bleached softwood kraft pulp fiber with high alpha cellulose content and increased brightness and whiteness is provided. Methods for making the kraft fiber and products made from it are also described.

A modified kraft pulp fiber with unique properties is provided. The modified fiber can be a modified bleached kraft fiber that is almost indistinguishable from its conventional counterpart, except that it has a low degree of polymerization (DP). Methods for making the modified fiber and products made from it are also provided. The method can be a one step acidic, iron catalyzed peroxide treatment process that can be incorporated into a single stage of a multi-stage bleaching process. The products can be chemical cellulose feedstocks, microcrystalline cellulose feedstocks, fluff pulps and products made from them.