New promising composite materials useful in the adsorption of Cu(II) in ethanol based on cellulose and cellulose acetate
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This work describes for the first time the synthesis and characterization of new promising materials based on cellulose (Cel) and cellulose acetate (Celac), previously modified with aluminum oxide (CelAl and CelacAl) and post functionalized with 1,4-diazabicyclo [2.2.2] octane-n-propyltrimethoxysilane chloride (SiDbCl2), resulting the chemically modified hybrid materials CelAl/SiDbCl2 and CelacAl/SiDbCl2. The materials have shown to be useful in the adsorption of CuCl2 from ethanol, presenting high effective adsorption capacity. In the adsorption process, the copper ions diffuse into the solid solution interface and are retained as anionic complexes CuCl 3 − or CuCl 4 2− . An expressive effective adsorption capacity tQ, as well as the stability constants β1 and β2, were found for both adsorbents: (a) CelAl/DbCl2: tQ = 0.33 × 10−3 mol g−1, log β1 = 4.23 (±0.04) and log β2 = 6.99 (±0.03); (b) CelacAl/DbCl2: tQ = 0.48 × 10−3 mol g−1, log β1 = 5.1 (±0.1) and log β2 = 8.3 (±0.1). Both adsorbent materials are potentially useful in the pre-concentration and further analysis of Cu(II) present in trace amounts in ethanol, extensively used as an automotive fuel in Brazil. Regeneration of the adsorbents requires a very simple procedure consisting in their immersion in aqueous solution which causes the immediate release of the Cu(OH2) n 2+ species to the solution phase.
KeywordsCellulose Cellulose acetate Anionic copper complexes Stability constants
YG is indebted to FAPESP and CNPq for financial support; NF, HAM and LTA are indebted to FAPESP for MSc and Pos Doc fellowships. Authors wish to acknowledge Prof. Carol H. Collins for manuscript revision.
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