Adsorption of 3,4-dihydroxybenzoic acid onto hematite surface in aqueous medium: Importance of position of phenolic -OH groups and understanding of the same using catechol as an auxiliary model

作者：Saikia Nabanita; Sarma Jyotirmoy; Borah Jayanta M; Mahiuddin Sekh^*

来源：Journal of Colloid and Interface Science, 2013, 398: 227-233.

DOI：10.1016/j.jcis.2013.02.028

• Adsorption
• Catechol
• 3,4-Dihydroxybenzoic acid
• Hematite
• DRIFT spectra
• Mineral dissolution

A comparative adsorption kinetics, isotherms, dissolution and surface complexation of 3,4-dihydroxybenzoic acid (3,4-DHBA) and 1,2-dihydroxybenzene (catechol) at the hematite/electrolyte interface were investigated. The kinetics at pH 10 and 298.15 K suggested that the adsorption behaviour of 3,4-DHBA and catechol onto hematite surface is similar and attain same equilibration time of 60 min. The adsorption kinetics data of 3,4-DHBA and catechol fit the pseudo-second-order kinetic equation of nonlinear form best. The adsorption density of 3,4-DHBA at pH >= 9 increases and thereby mimics the behaviour of catechol. The solubility of hematite depends on both pH of the suspension and concentration of adsorbate. The inner-sphere complex is formed by 3,4-DHBA and catechol onto hematite surface but the mode orientation is likely to be different in the pH range 5-8 and 9-10. The advance microscopic scanning in conjunction with the vibration spectroscopy would provide better pictorial presentation of the mode of orientation of 3,4-DHBA and catechol onto hematite surface at different pH.

• 出版日期2013-5-15