Adsorption of 3,4-dihydroxybenzoic acid onto metal oxide surface and the specific ion effects
Jyotirmoy Sarma and Sekh Mahiuddin
Materials Science Division, CSIR-North East Institute of Science and Technology, Jorhat-785006, Assam, India
Simple dihydroxybenzoic acids (DHBA), natural organic matters (NOM) analogues of the biosphere, are important components in the aquatic eco-system [1,2]. They are responsible for a variety of processes that take place in the biosphere including accessibility of micronutrients for plants and several environmentally important geochemical processes such as mineral dissolution, metal-ion sequestration, redox reaction, pH buffering and stability of mineral colloids. 3,4-dihydroxybenzoic acid amongst all DHBA-isomers exhibits quite different adsorption behaviour at pH ≥ 9 and follows catechol adsorption pattern. On the other hand, catechol showed bilayer adsorption onto hematite at pH 5-8 and monolayer at pH ≥ 9. In this paper we report the adsorption behaviour of 3,4- dihydroxybenzoic acid onto alumina and hematite surface and using catechol as an auxiliary model and finally examined how simple ions modulate the adsorption behaviour.
Keywords: Adsorption, Catechol, Dihydroxybenzoic acid, Specific ion effects
1. Chebbi, A.; Carlier, P. Atmos. Environ. 1996, 24, 4233-4249.
2. Strobel, B.W. Geoderma 2001, 99, 169-198.