科研之友
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摘要
This research focused on developing a series of (G1.0, G2.0, G3.0 and G4.0) PAMAM dendrimers modified attapulgite (ATP) sorbents (G1.0-G4.0 PAMAM-ATP) to remove Hg(II) from aqueous solution. The effects of several parameters including solution pH, contacting time, temperature and initial Hg(II) ion concentration were studied. Batch sorption results showed that the adsorption process was rapid and over 90% of Hg(II) was removed within 80 min at optimal pH 5.0. The adsorption capacity of PAMAM-ATP adsorbents followed the order of G2.0 > G1.0 > G3.0 > G4.0 and the maximum adsorption capacities significantly increased from 5 mg/g (raw ATP), 90 mg/g (amine modified ATP, M-ATP), 192.5 mg/g (polyacrylamine modified ATP, PAM-ATP) by previous similar studies to 200.8 mg/g (G2.0-PAMAM-ATP). Kinetics of adsorption was suitable for pseudosecond-order and controlled by chemical adsorption over a whole sorption range. The adsorption capacities increased as temperature rise from 283 to 303 K and the thermodynamics properties implied that the adsorption processes was spontaneous and endothermic. Thus, the adsorption capacities decreased when the temperature was above 303 K. The isotherm adsorption was described by Langmuir model well with monolayer behavior. A specific coordination between Hg(II) and the N, O atoms on the functional groups of PAMAM-ATP surface was determined by XPS analysis. Furthermore, the maximum adsorption capacity of the regenerated G2.0-PAMAMATP sorbents could still be higher than 90% after five cycles by acid treatment. The favorable adsorption capacity compared with other adsorbents exhibited that G2.0-PAMAM-ATP was an excellent renewable sorbent for Hg(II) removal.
