A process for producing a nanofibrillar cellulose hydrogel comprises obtaining bleached cellulose pulp fibers and providing an aqueous suspension thereof; and subjecting the cellulose pulp fibers in the aqueous suspension to at least 2 cycles of high pressure mechanical disintegration to obtain a nanofibrillar cellulose hydrogel and thereby reducing the number of viable microorganisms present in the suspension by a factor of at least 10.sup.2; wherein all steps of the process after obtaining the bleached cellulose pulp fibers are performed under conditions of ISO 8 of ISO 14644-1 cleanroom standards or stricter. A nanofibrillar cellulose hydrogel, a system for producing the same and the use of a disintegrating apparatus are also disclosed.

A process for producing a nanofibrillar cellulose hydrogel comprises obtaining bleached cellulose pulp fibers and providing an aqueous suspension thereof; and subjecting the cellulose pulp fibers in the aqueous suspension to at least 2 cycles of high pressure mechanical disintegration to obtain a nanofibrillar cellulose hydrogel and thereby reducing the number of viable microorganisms present in the suspension by a factor of at least 10.sup.2; wherein all steps of the process after obtaining the bleached cellulose pulp fibers are performed under conditions of ISO 8 of ISO 14644-1 cleanroom standards or stricter. A nanofibrillar cellulose hydrogel, a system for producing the same and the use of a disintegrating apparatus are also disclosed.

Fibres and nonwoven materials comprising microfibrillated cellulose, and optionally inorganic particulate material and/or additional additives, and optionally a water soluble or dispersible polymer. Nonwoven materials made from fibres comprising microfibrillated cellulose, and optionally inorganic particulate material and/or a water soluble or dispersible polymer.

Fibres and nonwoven materials comprising microfibrillated cellulose, and optionally inorganic particulate material and/or additional additives, and optionally a water soluble or dispersible polymer. Nonwoven materials made from fibres comprising microfibrillated cellulose, and optionally inorganic particulate material and/or a water soluble or dispersible polymer.

The present invention provides a powder-assembled composite micro-nano fiber and a method for preparing the powder-assembled composite micro-nano fiber. The method includes the following steps: (1) preparing two-dimensional cellulose from a cellulose-raw-material; (2) dispersing the two-dimensional cellulose and a powder material in a solvent to form a mixed suspension; and (3) performing freeze drying on the mixed suspension to obtain the powder-assembled composite micro-nano fiber, wherein a temperature difference between two ends in a vertical direction of the mixed suspension is controlled to be 10-100? C. in a freezing process of the freeze drying. In the present invention, a new non-destructive processing path from primary particles to macro applications is constructed, and rich material platforms and infinite possibilities are provided for basic studies and technical applications. The technology will play a huge role in energy, medical material, environment, protection, catalysis, photoelectricity, food engineering, daily necessity and other vast fields.

The present invention provides a powder-assembled composite micro-nano fiber and a method for preparing the powder-assembled composite micro-nano fiber. The method includes the following steps: (1) preparing two-dimensional cellulose from a cellulose-raw-material; (2) dispersing the two-dimensional cellulose and a powder material in a solvent to form a mixed suspension; and (3) performing freeze drying on the mixed suspension to obtain the powder-assembled composite micro-nano fiber, wherein a temperature difference between two ends in a vertical direction of the mixed suspension is controlled to be 10-100? C. in a freezing process of the freeze drying. In the present invention, a new non-destructive processing path from primary particles to macro applications is constructed, and rich material platforms and infinite possibilities are provided for basic studies and technical applications. The technology will play a huge role in energy, medical material, environment, protection, catalysis, photoelectricity, food engineering, daily necessity and other vast fields.

A method for preparing an aqueous suspension may include providing a fibrous substrate comprising cellulose having a Canadian Standard freeness equal to or less than 450 cm.sup.3, and microfibrillating the fibrous substrate in an aqueous environment by grinding in the presence of a grinding medium consisting essentially of mullite. The grinding may be carried out in the absence of grindable inorganic particulate material. The grinding medium may be present in an amount of at least about 10% by volume of the aqueous environment. The microfibrillated cellulose may have a fibre steepness of from about 20 to about 50.

A method for preparing an aqueous suspension may include providing a fibrous substrate comprising cellulose having a Canadian Standard freeness equal to or less than 450 cm.sup.3, and microfibrillating the fibrous substrate in an aqueous environment by grinding in the presence of a grinding medium consisting essentially of mullite. The grinding may be carried out in the absence of grindable inorganic particulate material. The grinding medium may be present in an amount of at least about 10% by volume of the aqueous environment. The microfibrillated cellulose may have a fibre steepness of from about 20 to about 50.

Hydrothermal pretreatment of mechanically compressed straw in unagitated reactors provides a simple and inexpensive solution to poor C5 monomer yields with autohydrolysis processes. Unlike raw straw, compressed straw pellets or briquettes can be pretreated on commercial scale using unagitated batch reactors or simplified unagitated continuous systems. The chemistry of hydrothermal pretreatment is thereby altered such that loss of C5 sugars to unwanted byproduct reactions is reduced. With compressed straw, water content can be introduced within the reactor while it is pressurized, which reduces energy costs and capital expense. Provided are methods of processing straw feedstocks using semi-continuous or continuous systems and a pretreatment reactor adapted to processes compressed straw with high throughput through a small reactor volume in which water content is added within the reactor under pressure.

Hydrothermal pretreatment of mechanically compressed straw in unagitated reactors provides a simple and inexpensive solution to poor C5 monomer yields with autohydrolysis processes. Unlike raw straw, compressed straw pellets or briquettes can be pretreated on commercial scale using unagitated batch reactors or simplified unagitated continuous systems. The chemistry of hydrothermal pretreatment is thereby altered such that loss of C5 sugars to unwanted byproduct reactions is reduced. With compressed straw, water content can be introduced within the reactor while it is pressurized, which reduces energy costs and capital expense. Provided are methods of processing straw feedstocks using semi-continuous or continuous systems and a pretreatment reactor adapted to processes compressed straw with high throughput through a small reactor volume in which water content is added within the reactor under pressure.