کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4705161 1352945 2005 13 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Surface complexation model for multisite adsorption of copper(II) onto kaolinite
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
Surface complexation model for multisite adsorption of copper(II) onto kaolinite
چکیده انگلیسی

We measured the adsorption of Cu(II) onto kaolinite from pH 3–7 at constant ionic strength. EXAFS spectra show that Cu(II) adsorbs as (CuO4Hn)n−6 and binuclear (Cu2O6Hn)n−8 inner-sphere complexes on variable-charge ≡AlOH sites and as Cu2+ on ion exchangeable ≡X--H+ sites. Sorption isotherms and EXAFS spectra show that surface precipitates have not formed at least up to pH 6.5. Inner-sphere complexes are bound to the kaolinite surface by corner-sharing with two or three edge-sharing Al(O,OH)6 polyhedra. Our interpretation of the EXAFS data are supported by ab initio (density functional theory) geometries of analog clusters simulating Cu complexes on the {110} and {010} crystal edges and at the ditrigonal cavity sites on the {001}. Having identified the bidentate (≡AlOH)2Cu(OH)20, tridentate (≡Al3O(OH)2)Cu2(OH)30 and ≡X--Cu2+ surface complexes, the experimental copper(II) adsorption data can be fit to the reactions 2≡AlOH+Cu2++2H2O=(≡AlOH)2Cu(OH)20+2H+3(≡AlOH)+2Cu2++3H2O=(≡Al3O(OH)2)Cu2(OH)30+4H+ and equation(A1)≡X−--H++Cu2+=≡X−--Cu2++X+.≡X−--H++Cu2+=≡X−--Cu2++X+.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Geochimica et Cosmochimica Acta - Volume 69, Issue 15, 1 August 2005, Pages 3733–3745
نویسندگان
, ,