Method of de-inking paper and other cellulosic materials

Abstract

A method of de-inking cellulosic fibrous materials comprising: 1) admixing an alkaline reagent with hydrogen peroxide and an aqueous suspension of inked cellulosic fibrous material in amounts whereby the alkaline reagent and hydrogen peroxide react at the ink particle/cellulosic fiber interfaces to dislodge the ink particles from the cellulosic materials; and, 2) removing the dislodged ink particles from the aqueous suspension, wherein the alkaline reagent comprises sodium carbonate or a mixture of sodium carbonate and a) ammonium hydroxide, b) sodium bicarbonate or c) mixtures of sodium carbonate and ammonium hydroxide.

1 . A method of de-inking cellulosic fibrous materials comprising: 
 1) admixing an alkaline reagent with hydrogen peroxide and an aqueous suspension of inked cellulosic fibrous material in amounts whereby said alkaline reagent and hydrogen peroxide react at the ink particle/cellulosic fiber interfaces to dislodge said ink particles from said cellulosic materials; and    2) removing said dislodged ink particles from said aqueous suspension, wherein said alkaline reagent consists essentially of sodium carbonate or a mixture of sodium carbonate and a) ammonium hydroxide, b) sodium bicarbonate or c) mixtures of sodium bicarbonate and ammonium hydroxide.    
     
     
         2 . The method of  claim 1  wherein said aqueous suspension of inked cellulosic material is pulped wastepaper.  
     
     
         3 . The method of  claim 2  wherein said wastepaper is newsprint.  
     
     
         4 . The method of  claim 1  including the step of: 
 3) removing de-inked cellulosic fibers from said aqueous suspension.    
     
     
         5 . The method of  claim 4  including the step of: 
 4) recycling the aqueous liquid remaining after removal of said de-inked cellulosic fibers to step  1 ).    
     
     
         6 . The method of  claim 1  wherein said aqueous suspension contains up to about 2% solids loading.  
     
     
         7 . The method of  claim 1  wherein said aqueous suspension, after admixture with said alkaline reagent and hydrogen peroxide, has a pH in the range of from about 9.5 to about 10.0.  
     
     
         8 . The method of  claim 1  wherein the amount of alkaline reagent admixed with said aqueous suspension is from about 0.5 to about 1.0 weight percent by weight of dry cellulosic material.  
     
     
         9 . The method of  claim 1  wherein said alkaline reagent admixed with said aqueous suspension is in the form of a 0.01% to 0.02%, by weight, aqueous solution.  
     
     
         10 . The method of  claim 1  wherein said dislodged ink particles are removed from said aqueous suspension by flotation.  
     
     
         11 . The method of  claim 10  wherein said aqueous suspension is sparged with a gas to aid said flotation of ink particles.  
     
     
         12 . The method of  claim 11  wherein said gas is air.  
     
     
         13 . The method of claims  1  or  5  conducted continuously.  
     
     
         14 . The method of  claim 1  wherein the amount of alkaline reagent is in the range of from about 0.5% to about 1.0%, by weight, based on the dry weight of the cellulosic material.  
     
     
         15 . In a method for recycling waste cellulosic material, the improvement comprising de-inking cellulosic fibrous materials by a method comprising: 
 1) admixing an alkaline reagent with hydrogen peroxide and an aqueous suspension of inked cellulosic fibrous material in amounts whereby said alkaline reagent and hydrogen peroxide react at the ink particle/cellulosic fiber interfaces to dislodge said ink particles from said cellulosic materials; and    2) removing said dislodged ink particles from said aqueous suspension, wherein said alkaline reagent consists essentially of sodium carbonate or a mixture of sodium carbonate and a) ammonium hydroxide, b) sodium bicarbonate or c) mixtures of sodium bicarbonate and ammonium hydroxide.    
     
     
         16 . The method of  claim 14  wherein the amount of alkaline reagent is in the range of from about 0.5% to about 1.0%, by weight, based on the dry weight of the cellulosic material.  
     
     
         17 . A composition for de-inking cellulosic fibrous materials in kit form comprising separately packaged effective amounts of: a) an alkaline reagent and b) hydrogen peroxide, wherein said alkaline reagent comprises sodium carbonate, or a mixture of sodium carbonate and a) ammonium hydroxide, b) sodium bicarbonate or c) mixtures of sodium bicarbonate and ammonium hydroxide.  
     
     
         18 . (canceled)  
     
     
         19 . An article of manufacture comprising separate packages and an alkaline reagent contained within one of said packages and hydrogen peroxide contained within another of said packages, wherein said packaged materials are effective for de-inking cellulosic fibrous materials, and wherein said packages also comprise a label which indicates that said packaged materials can be used for de-inking cellulosic fibrous materials, wherein said alkaline reagent comprises sodium carbonate, or a mixture of sodium carbonate and a) ammonium hydroxide, b) sodium bicarbonate or c) mixtures of sodium bicarbonate and ammonium hydroxide.  
     
     
         20 . (canceled)