Abstract: An effluent produced in oxidation of a cellulosic material with an oxidizing agent in the presence of an N-oxyl compound and a bromide and/or iodide is deionized by electrodialysis to an inorganic salt concentration of less than 0.4%, whereby the N-oxyl compound in the effluent is concentrated and recovered. The N-oxyl compound thus recovered can be reused in oxidation of a cellulosic material. Preferably, the effluent is subjected to reduction treatment and ion exchange resin treatment prior to the electrodialysis.

Abstract: A papermaking additive comprising cellulose nanofibers whose aqueous solution at a concentration of 2% (w/v) has a B-type viscosity (60 rpm, 20° C.) of 500 to 7000 mPa·s, preferably 500 to 2000 mPa·s is used to prepare a paper having improved air resistance and smoothness. This additive is prepared by oxidizing a cellulosic material with an oxidizing agent in the presence of (1) N-oxyl compound(s) and (2) bromide, iodide or a mixture thereof to prepare oxidized cellulose, and finely grinding the oxidized cellulose in a wet condition to convert the oxidized cellulose into nanofibers.

Abstract: Cellulose nanofibers are produced using a 4-hydroxy TEMPO derivative by treating a cellulosic material with an oxidizing agent in water in the presence of a cellulose oxidation catalyst containing an N-oxyl compound to prepare oxidized cellulos, and microfibrillating the oxidized cellulose.

Abstract: An effluent produced in oxidation of a cellulosic material with an oxidizing agent in the presence of an N-oxyl compound and a bromide and/or iodide is deionized by electrodialysis to an inorganic salt concentration of less than 0.4%, whereby the N-oxyl compound in the effluent is concentrated and recovered. The N-oxyl compound thus recovered can be reused in oxidation of a cellulosic material. Preferably, the effluent is subjected to reduction treatment and ion exchange resin treatment prior to the electrodialysis.

Abstract: A cellulosic material is oxidized with an oxidizing agent in the presence of (1) an N-oxyl compound and (2) a bromide, an iodide or a mixture thereof. The resulting material is subjected to defibration and dispersion treatment to prepare a cellulose nanofiber dispersion liquid. The dispersion liquid thus obtained is acidified so that the cellulose nanofibers are aggregated to form a gelatinous substance. Ultimately, the gelatinous substance is treated mechanically to obtain a cellulose gel dispersion liquid which has low water absorbency and does not tend to swell.

Abstract: A papermaking additive comprising cellulose nanofibers whose aqueous solution at a concentration of 2% (w/v) has a B-type viscosity (60 rpm, 20° C.) of 500 to 7000 mPa·s, preferably 500 to 2000 mPa·s is used to prepare a paper having improved air resistance and smoothness. This additive is prepared by oxidizing a cellulosic material with an oxidizing agent in the presence of (1) N-oxyl compound (s) and (2) bromide, iodide or a mixture thereof to prepare oxidized cellulose, and finely grinding the oxidized cellulose in a wet condition to convert the oxidized cellulose into nanofibers.

Abstract: The present invention aims to provide a process for producing cellulose nanofibers using a 4-hydroxy TEMPO derivative less expensive than TEMPO and a process capable of rapidly producing homogeneous cellulose nanofibers.