This paper presents a sequential injection system associated with a tangential filtration unit and an ultraviolet detector for on-line monitoring of fulvic acid sorption onto two modified vermiculites. With the proposed approach it was possible to improve the temporal resolution in the investigation of the equilibrium time needed for the system sorbent-sorbate to reach the chemical equilibrium. Sorption onto a 10 g L-1 suspension of vermiculite material modified by intercalation of polyhydroxycations of Fe(III) was fast, reaching the equilibrium after 4 min of contact time, and resulting in sorption of 97.9 % of the initial 10 mg L-1 fulvic acid concentration. Sorption onto a 10 g L-1 suspension of an organic vermiculite which was modified by ion exchange with hexadecyltrimethylammonium bromide exhibited a fast initial rate of sorption, followed by desorption and re-adsorption processes, reaching the equilibrium after 30 min of contact time, with sorption of 98% of the initial 10 mg L-1 fulvic acid concentration.
flow analysis; natural organic matter; sorption; real-time analyses
