The Dow Chemical Company

Robert J Michalowski

David A Wilson

Steven H Christiansen

Jaime Simon

R Keith Frank

Walter L Vaughn

Jimmy Myers

Teresa Littleton

The invention is an improvement in a process for making cellulosic articles said process involving a separation of cellulosic material from a mixture containing a liquid, metal cations, and cellulosic material. The improvement involves adding to the mixture at least one retaining material which binds at least one metal cation and, in the separation, is retained with the cellulosic material. Suitable retaining agents are either organic or inorganic and include chelate-forming polymers, both synthetic and natural, colloidal suspensions of inorganic compounds, and mixed metal hydroxides. In each case, the metal cations remain in the cellulosic article, e.g. paper, rather going into waste water from which they would otherwise need to be removed.

Process for removing metal ions from liquids

Bleaching of wood pulp is improved by the combination of a pretreatment of the pulp with a polyaminocarboxylic acid, e.g. ethylenediaminetetraacetic acid, prior to bleaching with an alkaline aqueous peroxide solution containing a stabilizing amount of an aminophosphonic acid derivative together with a polymer of an unsaturated carboxylic acid or amide or an alkylsulfonic acid substituted amide.

Bleaching of cellulosic pulps using hydrogen peroxide

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Midland, MI, United States of America

Robert J Michalowski