The present invention relates to a method for bleaching an unbleached or pre-bleached paper pulp comprising at least the following consecutive steps: a) preparing an unbleached or pre-bleached paper pulp having a pH of at least 8, b) bringing the paper pulp obtained at the end of step a) into contact with chlorine dioxide, c) when the pH of the paper pulp obtained from step b) is lower than 10, adding at least one Brønsted base to the paper pulp, d) adding hydrogen peroxide to the paper pulp obtained at the end of step c), e) maintaining the paper pulp obtained at the end of step d) in a first bleaching tower, f) optionally, adding sulphuric acid to the paper pulp obtained at the end of step e) and maintaining the obtained paper pulp in a second bleaching tower, the method dispensing with the need for a step of washing the paper pulp before the end of step e), and, if applicable, before the end of step f).

Recycle fiber bleaching includes an oxygen pre-treatment to activate the fiber for further bleaching. A preferred method of making a high brightness papermaking pulp from recycled cellulose fiber includes: (a) pre-treating a first recycled cellulosic fiber mix with oxygen, said first recycled cellulosic fiber mix having a first high Kappa number prior to pre-treatment and a reduced Kappa number after pre-treatment that is lower than said first high Kappa number; and (b) blending the pre-treated first recycled cellulosic fiber mix with the reduced Kappa number with a second recycled cellulosic fiber mix having a second Kappa number lower than the first high Kappa number of the first recycled cellulosic fiber mix; and (c) oxidatively bleaching the blended recycled cellulosic fiber mix of step (b); and optionally (d) reductively bleaching the blended recycled cellulosic fiber mix of step (c).

An aqueous composition comprising: sulfuric acid; a modifying agent comprising a carbonyl-containing nitrogenous base compound; and a peroxide. Said composition being capable of delignifying biomass under milder conditions than conditions under which kraft pulping takes place.

The present invention provides a method of producing an improved cellulose pulp consisting of cellulose fibers of a desired length, such as cellulose fibers having a length-weighted average fiber length Lc(l)>0.6 mm and its use in cellulose pulp-comprising products, such as packaging material with improved properties.

The present invention relates to a method for increasing the rate of enzymatic hydrolysis of a polysaccharide substrate, said method comprising at least one step of: enzymatic hydrolysis of said substrate with a mixture of enzymes, said mixture comprising at least one enzyme selected from lytic polysaccharide monooxygenases; in the presence of chemically modified lignin, wherein during at least part of the time of said step of enzymatic hydrolysis, H.sub.2O.sub.2 is supplied to the reaction mixture comprising said substrate, said mixture of enzymes and said chemically modified lignin, either from an external source or by generation in situ.

The present invention involves an environmentally friendly process and apparatus for the delignification of lignin-containing materials, such as cardboard newspaper or agricultural or tree pruning wastes. This process produces cellulose using low temperatures and low concentrations of hydrogen peroxide. It can be performed using a column fitted with a semipermeable gasket that pressurizes the column by retaining oxygen released by action of the hydrogen peroxide on a lignin-containing material.

The invention relates to a method for bleaching pulp formed from recycled textile material comprising cellulose, said method comprising ozone bleaching (3; 13a, 13b) of said pulp by means of adding ozone at a charge of at least 12 kg/odt, wherein said ozone bleaching (13a, 13b) is performed as two subsequent steps, each comprising adding ozone at a charge such that the overall charge is at least 12 kg/odt.

Aqueous solutions of hydrogen peroxide are stabilized by at least one polymeric stabilizer selected from phosphino polycarboxylic acids, poly(acrylic acid)-acrylamidoalkylpropane sulfonic acid co-polymers and poly(acrylic acid)-acrylamidoalkylpropane sulfonic acid-sulfonated styrene terpolymers. The polymer-stabilized hydrogen peroxide solutions have applications in aseptic packaging, electronics manufacture, and pulp and paper bleaching.

The present invention involves an environmentally friendly process and apparatus for the delignification of lignin-containing materials, such as cardboard newspaper or agricultural or tree pruning wastes. This process produces cellulose using low temperatures and low concentrations of hydrogen peroxide. It can be performed using a column fitted with a semipermeable gasket that pressurizes the column by retaining oxygen released by action of the hydrogen peroxide on a lignin-containing material.

A process comprising treating a lignocellulosic material preferably pulp in the presence of a transition metal catalyst with a oxidizing agent selected from a group consisting of hydrogen peroxide, hypochlorite, hypochlorous acid and any combination thereof to form a treated lignocellulosic material having a viscosity equal to or less than about 17 cp and having reducing functional groups selected from the group consisting of aldehyde and aldehyde type functional groups at the C6 and C1 positions but predominating at the C1 position.