Kraft pulp, carboxyl content hardwood

This poses a question concerning deacidification. If a deacidification procedure does not remove aluminum from the cellulose carboxyls, will the paper have the stability that one would expect from a paper with an alkaline filler In an attempt to answer this question, a series of hand-sheets was made from a hardwood kraft pulp. This pulp was selected because (a) it had a carboxyl content of 5.75 mmol/100 g pulp, which is similar to that of some old papers (b) it was easy to beat in a laboratory beater and (c) the physical properties of the handsheets were in the "old... 

A hardwood kraft pulp was used for handsheets. This had a carboxyl content of about 5.75 mmols/100 g pulp. 

The exact formation of salts with cellulosic carboxyls has never been resolved. The carboxyl content of the hardwood kraft pulp is about 0.0575 mmol/gram of pulp. If one adds up the meq of metals that have been sorbed by g cellulose, the milliequivalents of metals exceeds the milliequivalents of carboxlys. If one assumes that 1 mmol of metal reacts with 1 meq of carboxyl, then there is a surplus of carboxyls. It would appear that the reaction of metals with carboxyls is nonstoichio-metric. Using aluminum sulfate as an example, the product of the... 

In order to translate this into the real world of papermaking, and of deacidification, handsheets were made under controlled conditions from the hardwood kraft pulp. The pulp was first treated with calcium acetate solution to cover the carboxyls with calcium. Some of this pulp was then treated with A12(S04)3 solution. Handsheets were then made from the original pulp, from the calcium pulp, and from the aluminum pulp. Some of these handsheets were deacidified. The metals contents of these handsheets were then determined and the data are given in Table XVII. 

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