Adsorption of sodium alginate onto sodium montmorillonite

The interactions between polymers such polysaccharides and clay can be controlled by different factors, such as the functional groups of the polymers, pH and salinity of the suspension. This study was conducted to understand the various kinds of interactions between sodium Alginate (NaAlg) a polyanion negatively charged and sodium montmorillonite (NaMmt). The adsorption isotherms of alginate onto montmorillonite at neutral and acidic pH show two different behavior, a strong adsorption of alginate at acidic (pH 960 mg/g) while for neutral pH the adsorbed amount is very low compared to acidic medium (-200 mg/g). The adsorption of NaAlg by NaMmt at low pH reduce the Zeta potential of the montmorillonite particles due to the protonated carboxylic groups fixed by the montmorillonite surface, diversly at neutral pH, the negative Zeta potential value increase as long as the initial polymer concentration increase till a maximum of (-45 mV), due to negative charge presented by both the NaMmt and NaAlg at this range of pH. XRD analysis was used to develop an overview about the interactions between the polyanion and the clay. The results shows that the modification of NaMmt at the two pH ranges has no effect on the dspacing of NaMmt, accordingly the adsorption occurs on the external surface of the clay layers without intercalation in interlayer of the clay. the small displacement and widening of the 001 line is due to the aggregation of the clay particles by adsorption of few polymeric chains on external surface. (c) 2021 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the Fourth edition of the International Conference on Materials & Environmental Science.