Synergic adsorption of Pb2+ and reactive dye--RB5 on two series of organomodified bentonites.

Two series of organobentonites (OBs) were synthesized from Na(+)-exchanged bentonite clay from Bogovina, Serbia. In the first series the starting material was modified using hexadecyltrimethylammonium (HDTMA(+)) ion in the amounts corresponding to 0.2, 0.5, 1.0 and 2.0 of the CEC value. The second series was obtained using quaternary alkyl ammonium cations (QAACs) with different alkyl chain lengths: hexadecyltrimethylammonium (HDTMA(+)), dodecyltrimethylammonium (DDTMA(+)) and tetramethylammonium (TMA(+)) ions. The synthesized OBs were characterized. The adsorption of anionic reactive dye Reactive Black 5 (RB5) and Pb(2+) from single component solutions and their bi-component solution was investigated for both series of OBs. The adsorptive properties of the OBs were correlated to the amount and type of incorporated QAACs. The correlation was tested using different mathematical models and best fits were found. Experimental results showed that simultaneous adsorption of RB5 and Pb(2+) exhibited synergic effect. The adsorption capacity for both RB5 and Pb(2+) was higher in their bi-component solution than in single-component solutions. These results indicate the creation of new adsorption sites during the simultaneous adsorption.