Polyelectrolyte behavior of chemically modified cotton cellulose

Abstract

Ion exchange and sorption of charged molecules such as dyes, crosslinking agents, etc., by cotton cellulose very much depend on the charge on cellulose, which in turn is known to depend on the external pH of the medium. In order to understand the role of various fixed groups in cellulose in its polyelectrolyte behavior, the standard cellulose was deliberately oxidized with nitrogen dioxide and sodium periodate, and the sorption of formaldehyde and dimethylol dihydroxyethylene urea by these oxycelluloses as well as by alkali‐treated nitrogen dioxide–oxycellulose was investigated. The results obtained are interpreted in terms of polyampholyte behavior of oxycellulose. The nitrogen dioxide–oxycellulose is positively charged and is a polycation in acidic medium due to protonation of aldehyde groups while it is negatively charged and acts as a polyanion in slightly acidic to alkaline medium due to dissociation of carboxyl groups.

Salt sorption on regenerated cellulosic fibers: electrokinetic measurements

“…The literature reported pKa of cellulosic carboxyl and hydroxyl groups are in the regions of 3-4 and 9-10 respectively (Farrar and Neale 1952;Räsänen et al 2001;Bygrave and Englezos 1998;Saric and Schofield 1946;Bagrovskaya et al 2002;Shet and Yabani 1982;Fras et al 2004). The pH of all salt-salt streaming solutions was in the range of 5-6.…”

Oxycellulose modification

“…Monocarboxy cellulose is negatively charged and acts as a polyanion in slightly acidic to alkaline media due to dissociation of carboxyl groups. 10 In the present investigation, IR results of modi®ed oxycellulose are analysed and discussed. Refaktan K, a liquid of density 1.093 from Chemotex as, Decin 32 ± Boltice nad Labem, Czech Republic, was activated before use by mixing 1 kg of Refaktan K with 1.33 M NaOH with gentle manual stirring to full solubility of both compounds.…”