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

Email: mahirrljt@yahoo.com

Abstract:

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

References:

1.   Chebbi, A.; Carlier, P. Atmos. Environ. 1996, 24, 4233-4249.

2.   Strobel, B.W. Geoderma 2001, 99, 169-198.