Interaction of sodium alginate biopolymer with sodium dodecyl sulfate in aqueous medium and different additive solutions at several temperatures

Abstract

Interactions between sodium dodecyl sulfate (SDS) and sodium alginate (NaAlg) in aq. salts/hydrotrope (HDT) media have been investigated using conductivity method with changing the micellar parameters (e.g., critical micelles concentration (CMC), extent of micelle ionization (α), and bound counterions (β)) and thermodynamics of the micellization of SDS + NaAlg mixtures. CMC values and α were assessed from the plots of conductivity versus [SDS]. The micellization of SDS + NaAlg was enhanced in aq. electrolyte and aq. HDTs media. The formation of SDS + NaAlg micelles was found to happen delayed with an increase in temperature in water and aq. 10% (w/w) glycerol (GLY) solution, while in other employed solvents, micelle creation was observed to favor with an upsurge of working temperature. Thermodynamics of SDS + NaAlg mixtures were computed from temperature dependency of CMC. The values of ΔG 0 m were found negative for all the experiments, thereby, examined. The values of Δ H m 0 in the micellization of SDS + NaAlg mixtures in H2O, H2O + sodium acetate (NaOAc), H2O + sodium benzoate (NaBenz), and H2O + 4-amino benzoic acid (4-ABA) media were observed positive, and, hence, the process was endothermic in these solvents. Micellization of SDS + NaAlg was exothermic in 10% (w/w) glycerol (GLY) solutions at all temperatures and in H2O + NaCl at 298.15 and 303.15 K. The values of Δ H m 0 and Δ S m 0 for SDS + NaAlg show that the hydrophobic, van der Waals and exothermic interactions are the driving forces between SDS and NaAlg in electrolytes and HDT media.