Calorimetry of Poly-(Acrylic Acid) Adsorption on TiO2

✍ Scribed by Marcel R. Böhmer; Younès El Attar Sofi; Alain Foissy

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 520 KB
• Volume: 164
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1994.1151

✦ Synopsis

The adsorption of low molecular weight poly-(acrylic acid) (PAA) from aqueous solutions on (\mathrm{TiO}{2}) (anatase) has been studied and at (\mathrm{pH} 10) as a function of the electrolyte type and concentration. At low (\mathrm{pH}) an exothermic heat of adsorption is found but at high (\mathrm{pH}) in (\mathbf{C a C l}{2}) and (\mathrm{NaCl}) solutions heat is consumed during adsorption. This endothermic effect is related to specific interactions between the cations and the (\mathrm{TiO}{2}) surface. If a Ca-salt is used the endothermic effect also originates from (\mathrm{Ca}^{2+}) PAA interactions. The most likely driving force for PAA adsorption on (\mathrm{TiO}{2}) at high (\mathrm{pH}) is the entropy gain by the release of hydration water of specifically interacting ions. (1994 Academic Press, Inc.