Abstract
To clarify the differences in the mechanism of adsorption among cadmium (II), lead (II), and mercury (II) by wood charcoal produced from sugi (Cryptomeria japonica D. Don), the adsorption characteristics of these heavy metals in mixed aqueous solutions were examined.In the case cadmium (II) and lead (II) are present in the same aqueous solution system, the adsorption of each of them by sugi wood charcoal decreases. It is therefore assumed that the same mechanism of adsorption is involved in the adsorption of cadmium (II) and lead (II) by sugi wood charcoal, and that these heavy metals compete for this adsorption. Because the presence of mercury (II) does not affect the adsorption of cadmium (II) and lead (II), it is assumed that a different mechanism of adsorption is involved in the adsorption of mercury (II), and that mercury (II) does not take part in the competitive adsorption of cadmium (II) and lead (II).Regarding the mechanism of adsorption of cadmium (II) and lead (II) by sugi wood charcoal in an acidic solution, we inferred that when the cadmium (II) and lead (II) ions come in contact with the sugi wood charcoal surface in an aqueous solution, hydroxides are formed by a high concentration of alkali on the charcoal surface and deposited and stabilized on the surface or in the micro pores of the charcoal. It is assumed that the adsorption of mercury (II) by sugi wood charcoal occurs on the basic surface oxide, and that such chemical species of mercury as the complex anions [HgCl4]2- and [HgCl3]- and the non-charged complex [HgCl2] are adsorbed by sugi wood charcoal.Almost the entire quantity of the cadmium (II) and lead (II) adsorbed to sugi wood charcoal was desorbed at pH1.2, the recovery rate being 99% for cadmium (II) and 97% for lead (II). The mercury (II) adsorbed to sugi wood charcoal was not desorbed in the pH range from 1.2 to 9.0; its desorption characteristic was found to be quite different from that of cadmium (II) and lead (II). The difference in desorption characteristic is attributable to a difference in the mechanism of adsorption between mercury (II) and cadmium (II) or lead (II). The adsorption of mercury (II) by sugi wood charcoal is assumed to be much more irreversible than that of cadmium (II) and lead (II).
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
