The adsorption of HgCl2, [HgCl4]2– and Hg2+ onto a series ofactivated carbon fibres was studied. These included the as-received commercialactivated carbon fibre (K), that obtained after modification via by sulphuric acidoxidation (KAC) and that obtained after modification by reaction withpentaethylenehexamine (KBAS). The effects of concentration (10–1500 mg/l),solution pH (1–10) and temperature (25°C, 35°C and 45°C) were studied. Themercury(II) adsorption isotherms followed the Langmuir model with maximumadsorption capacities of 361.0, 142.2 and 300.3 mg/g for HgCl2, [HgCl4]2– andHg2+, respectively. Fibre K proved to have the highest adsorption capacitytowards HgCl2 but the best results for the adsorption of [HgCl4]2– and Hg2+ wereobtained with the fibre KAC. The performance of fibre KBAS was always worsethan those of the other two fibres tested. The negative values obtained for ΔH0and ΔG0 indicate that the adsorption was an exothermic and spontaneous processand also demonstrated that the adsorption of Hg(II) is a feasible process.
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