TY - JOUR
T1 - Arsenic(III) methylation in betaine-nontronite clay-water suspensions under environmental conditions
AU - Cervini-Silva, Javiera
AU - Hernández-Pineda, Jessica
AU - Rivas-Valdés, María Teresa
AU - Cornejo-Garrido, Hilda
AU - Guzmán, José
AU - Fernández-Lomelín, Pilar
AU - Del Razo, Luz Maria
PY - 2010/6
Y1 - 2010/6
N2 - This paper reports arsenic methylation in betaine-nontronite clay-water suspensions under environmental conditions. Two nontronites (<0.05mm), NAu-1 (green color, Al-enriched) and NAu-2 (brown color, Al-poor, contains tetrahedral Fe) from Uley Mine - South Australia were selected for this study. Betaine (pKa=1.83) was selected as methyl donor. The reaction between 5gL-1 clay, 20ppm As(III), and 0.4M betaine at 7≤pH0≤9 under anoxic conditions was studied. The presence of nontronite clays were found to favor As(III) conversion to monomethylarsenic (MMA). Arsenic conversion was found to be as high as 50.2ngMMA/ng As(III)0. Conversion of As was found to be more quantitative in the presence of NAu-2 ((Na0.72) [Si7.55 Al0.16Fe0.29][Al0.34 Fe3.54 Mg0.05] O20(OH)4) than NAu-1 ((Na1.05) [Si6.98 Al0.95Fe0.07][Al0.36 Fe3.61 Mg0.04] O20(OH)4). The inherent negative charge at the nontronite tetrahedral layer stabilizes positively charged organic intermediate-reaction species, thereby leading to decreases in the overall methylation activation energy. The outcome of this work shows that nontronite clays catalyze As methylation to MMA via non-enzymatic pathway(s) under environmental conditions.
AB - This paper reports arsenic methylation in betaine-nontronite clay-water suspensions under environmental conditions. Two nontronites (<0.05mm), NAu-1 (green color, Al-enriched) and NAu-2 (brown color, Al-poor, contains tetrahedral Fe) from Uley Mine - South Australia were selected for this study. Betaine (pKa=1.83) was selected as methyl donor. The reaction between 5gL-1 clay, 20ppm As(III), and 0.4M betaine at 7≤pH0≤9 under anoxic conditions was studied. The presence of nontronite clays were found to favor As(III) conversion to monomethylarsenic (MMA). Arsenic conversion was found to be as high as 50.2ngMMA/ng As(III)0. Conversion of As was found to be more quantitative in the presence of NAu-2 ((Na0.72) [Si7.55 Al0.16Fe0.29][Al0.34 Fe3.54 Mg0.05] O20(OH)4) than NAu-1 ((Na1.05) [Si6.98 Al0.95Fe0.07][Al0.36 Fe3.61 Mg0.04] O20(OH)4). The inherent negative charge at the nontronite tetrahedral layer stabilizes positively charged organic intermediate-reaction species, thereby leading to decreases in the overall methylation activation energy. The outcome of this work shows that nontronite clays catalyze As methylation to MMA via non-enzymatic pathway(s) under environmental conditions.
KW - Abiotic
KW - Methyl transfer
KW - Remediation
KW - Sediments
KW - Soils
KW - Toxicity
UR - http://www.scopus.com/inward/record.url?scp=77951498450&partnerID=8YFLogxK
U2 - 10.1016/j.jhazmat.2010.01.102
DO - 10.1016/j.jhazmat.2010.01.102
M3 - Artículo
C2 - 20189716
SN - 0304-3894
VL - 178
SP - 450
EP - 454
JO - Journal of Hazardous Materials
JF - Journal of Hazardous Materials
IS - 1-3
ER -