Some variations provide a process for producing a nanocellulose material, comprising: providing a biomass feedstock comprising a bleached or unbleached pulp material; fractionating the feedstock in the presence of an acid, a solvent for lignin, and water, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin; and mechanically treating the cellulose-rich solids to form cellulose fibrils and/or cellulose crystals, thereby generating a nanocellulose material. The process is preferably co-located with, or adjacent to, a mill that generates the pulp material. There are several advantages of a bolt-on AVAP? nanocellulose plant to an existing pulp mill, as disclosed herein.

Some variations provide a process for producing a nanocellulose material, comprising: providing a biomass feedstock comprising a bleached or unbleached pulp material; fractionating the feedstock in the presence of an acid, a solvent for lignin, and water, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin; and mechanically treating the cellulose-rich solids to form cellulose fibrils and/or cellulose crystals, thereby generating a nanocellulose material. The process is preferably co-located with, or adjacent to, a mill that generates the pulp material. There are several advantages of a bolt-on AVAP? nanocellulose plant to an existing pulp mill, as disclosed herein.

Various processes are disclosed for producing nanocellulose materials following steam extraction or hot-water digestion of biomass. Processes are also disclosed for producing nanocellulose materials from a wide variety of starting pulps or pretreated biomass feedstocks. The nanocellulose materials may be used as rheology modifiers in many applications. Water-based and oil-based drilling fluid formulations and additives are provided. Also, water-based and oil-based hydraulic fracturing fluid formulations and additives are provided. In other embodiments, polymer-nanocellulose composites are provided.

Some variations provide a process for producing a nanocellulose material, comprising: providing a biomass feedstock comprising a bleached or unbleached pulp material; fractionating the feedstock in the presence of an acid, a solvent for lignin, and water, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin; and mechanically treating the cellulose-rich solids to form cellulose fibrils and/or cellulose crystals, thereby generating a nanocellulose material. The process is preferably co-located with, or adjacent to, a mill that generates the pulp material. There are several advantages of a bolt-on AVAP? nanocellulose plant to an existing pulp mill, as disclosed herein.

Some variations provide a process for producing a nanocellulose material, comprising: providing a biomass feedstock comprising a bleached or unbleached pulp material; fractionating the feedstock in the presence of an acid, a solvent for lignin, and water, to generate cellulose-rich solids and a liquid containing hemicellulose and lignin; and mechanically treating the cellulose-rich solids to form cellulose fibrils and/or cellulose crystals, thereby generating a nanocellulose material. The process is preferably co-located with, or adjacent to, a mill that generates the pulp material. There are several advantages of a bolt-on AVAP? nanocellulose plant to an existing pulp mill, as disclosed herein.

A method for providing a treated cellulose-comprising mixed starting material (110), in particular a mixed starting material (110) for forming a, in particular regenerated, cellulosic molded body (102) is described. The method comprises: i) providing (10) a first starting material (101a) which comprises a lignocellulosic raw material, ii) providing (1) a second starting material (101b) which comprises a cellulose-containing lignin-free product, iii) mixing (15) the first starting material (101a) and the second starting material (101b) to a mixed starting material (101), and iv) at least partially commonly treating (20) the first starting material (101a) and the second starting material (101b) for obtaining the treated mixed starting material (101), in particular a mixed pulp.

A method for providing a treated cellulose-comprising mixed starting material (110), in particular a mixed starting material (110) for forming a, in particular regenerated, cellulosic molded body (102) is described. The method comprises: i) providing (10) a first starting material (101a) which comprises a lignocellulosic raw material, ii) providing (1) a second starting material (101b) which comprises a cellulose-containing lignin-free product, iii) mixing (15) the first starting material (101a) and the second starting material (101b) to a mixed starting material (101), and iv) at least partially commonly treating (20) the first starting material (101a) and the second starting material (101b) for obtaining the treated mixed starting material (101), in particular a mixed pulp.

An aqueous composition comprising: sulfuric acid; a modifying agent comprising an arylsulfonic acid; and a peroxide. Said composition being capable of delignifying biomass under milder conditions than conditions under which kraft pulping takes place.

An aqueous composition comprising: sulfuric acid; a modifying agent comprising an arylsulfonic acid; and a peroxide. Said composition being capable of delignifying biomass under milder conditions than conditions under which kraft pulping takes place.

Processes for pulping raw pulp material, such as wood chips, to provide pulp fibers having increased bulk, as well as bleaching the resulting pulp fibers to provide bleached pulp fibers having increased bulk. These pulp fibers and bleached pulp fibers may be incorporated into or used various products, such as multi-ply coated paperboards, fluff pulp, etc.