Competitive Removal of Cd2+ and Hg2+ Ions from Water Using Titanosilicate ETS-4: Kinetic Behaviour and Selectivity


Mercury and cadmium are priority hazardous substances. Some titanosilicates have been tested for the removal of Cd2+ and Hg2+ from single solutions by ion exchange. In this work, the competition between both contaminants for the exchanger binding sites of titanosilicate Engelhard titanosilicate material number 4 (ETS-4) was studied by performing batch experiments with aqueous solutions containing the two counter ions. The results evidenced the large capacity of ETS-4 and shown that the cadmium(II) diffusivity through the sorbent is higher than that of mercury(II). Furthermore, the ETS-4 exhibited higher kinetic and equilibrium selectivities for Cd2+, which attained values in the ranges 8.9-12.5 and 7.9-12.8, respectively. With respect to modelling, the pseudo-second-order equation described successfully the competitive removal of Cd2+ and Hg2+.



subject category

Environmental Sciences & Ecology; Meteorology & Atmospheric Sciences; Water Resources


Cardoso, SP; Lopes, CB; Pereira, E; Duarte, AC; Silva, CM

our authors


Authors acknowledge the Fundacao para a Ciencia e a Tecnologia for the financial support to Associate Laboratory CICECO (Pest-C/CTM/LA0011/2011), project PTDC/EQU-EQU/100476/2008, and research grants of C.B. Lopes (SFRH/BD/45156/2008) and S.P. Cardoso (SFRH/BD/75164/2010).

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