Incorporation of zero valent iron nanoparticles in the matrix of cationic resin beads for the remediation of Cr(VI) contaminated waters.
The objective of present study was to obtain the fixation of nano zero valent iron (nZVI) particles on a permeable matrix and evaluate the performance of this composite material for the removal of Cr(VI) from contaminated waters. The experiments were carried out using the cationic resin Dowex 50WX2 as porous support of the iron nanoparticles. The work was carried out in two phases. The first phase involved the fixation of nZVI on the resin matrix. The resin granules were initially mixed with a FeCl3 solution to obtain the adsorption of Fe(III). Then the Fe(III) loaded resin (RFe) was treated with polyphenol solutions to obtain the reduction of Fe(III) to the elemental state. Two polyphenol solutions were tested as reductants, i.e. green tea extract and gallic acid. Green tea was found to be inefficient, probably due to the relatively big size of the contained polyphenol molecules, but gallic acid molecules were able to reach adsorbed Fe(III) and reduce the cations to the elemental state. The second phase was focused on the investigation of Cr(VI) reduction kinetics using the nanoiron loaded resins (R-nFe). It was found that the reduction follows a kinetic law of first order with respect to Cr(VI) and to the embedded nanoiron. Compared to other similar products, this composite material was found to have comparable performance regarding reaction rates and higher degree of iron utilization. Namely the rate constant for the reduction of Cr(VI), in the presence of 1 mM nZVI, was equivalent to 1.4 h of half-life time at pH 3.2 and increased to 24 h at pH 8.5. The degree of iron utilization was as high as 0.8 mol of reduced Cr(VI) per mole of iron. It was also found that this composite material can be easily regenerated and reused for Cr(VI) reduction without significant loss of efficiency.
Sch. of Mining and Metallurgical Eng., National Technical University of Athens, 15780, Greece.
Aikaterini
A
Toli
Sch. of Mining and Metallurgical Eng., National Technical University of Athens, 15780, Greece.
Konstantina
K
Chalastara
Sch. of Mining and Metallurgical Eng., National Technical University of Athens, 15780, Greece.
Christiana
C
Mystrioti
Sch. of Mining and Metallurgical Eng., National Technical University of Athens, 15780, Greece.
Anthimos
A
Xenidis
Sch. of Mining and Metallurgical Eng., National Technical University of Athens, 15780, Greece. Electronic address: papasiop@metal.ntua.gr.
Nymphodora
N
Papassiopi
D000327:Adsorption; D002857:Chromium / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D007501:Iron / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D012117:Resins, Synthetic / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
D012117:Resins, Synthetic; D014874:Water Pollutants, Chemical; D002857:Chromium; C077982:Dowex 50; C074702:chromium hexavalent ion; D007501:Iron
Cation exchange resin; Groundwater remediation; Hexavalent chromium; Nano zero valent iron (nZVI)