Electrokinetic properties of chemically modified jute fabrics

In this work, the electrokinetic properties of alkali and oxidatively modified jute fabrics were studied. In contrast to the control fabric, chemically modified jute fabrics had a small positive zeta potential in the basic pH range, which could be attributed to the presence of sodium cations (originating from the undertaken chemical modifications) on their surfaces. At lower pH values, the samples modified under milder alkali and oxidative conditions had about 2.2–3.5 times lower zeta potential since the protonation process led to the formation of a higher positive charge in the electrochemical double layer, causing higher adsorption of Cl- (originating from the electrolyte). On the other hand, more intensive chemical modifications increased the zeta potential at lower pH values due to the increased amount of carboxyl groups and the ability of the fibres for water retention and hence swelling. The isoelectric point of the fabrics, having lower zeta potentials than that of the control fabric, was shifted towards higher pH values, indicating to a lower contribution of surface acidic groups of the fabrics. In the case of extensive oxidation conditions (60 and 90 min), the isoelectric point was shifted toward lower pH values because of lignin removal and the mentioned higher availability of newly formed carboxyl groups.