Abstract
Dimethylmonothioarsinic acid (DMMTAV) is a highly toxic, thiolated analogue of dimethylarsinic acid (DMAV). In comparison, a further thiolated analogue, dimethyldithioarsinic acid (DMDTAV), and DMAV both exhibit lower toxicity. To understand the environmental conditions responsible for forming DMMTAV, the kinetics of DMAV thiolation are examined. The thiolation of DMAV is pH-dependent and consists of two consecutive first-order reactions under excess sulfide conditions. The first thiolation of DMAV to form DMMTAV is faster than the second one to DMDTAV. DMMTAV is therefore an intermediate. The first reaction is first-order in H2S at pH 6.0 and 20 °C; therefore, the overall reaction is second-order and the rate coefficient in this condition is 0.0780 M-1 s-1. The rate coefficient significantly decreases at pH 8.0, indicating that H2S(aq) triggers the thiolation of DMAV. The second reaction rate is significantly decreased at pH 2.5; therefore, reaction under strongly acidic conditions leads to accumulation of highly toxic DMMTAV in the early stages of thiolation. The transformation of DMDTAV to DMMTAV is catalyzed in the presence of ferric iron. Formation of DMMTAV should be considered when assessing risk posed by arsenic under sulfidic or sulfate reducing conditions.
| Original language | English |
|---|---|
| Pages (from-to) | 11637-11645 |
| Number of pages | 9 |
| Journal | Environmental Science and Technology |
| Volume | 50 |
| Issue number | 21 |
| DOIs | |
| Publication status | Published - 2016 Nov 1 |
Fingerprint
All Science Journal Classification (ASJC) codes
- Chemistry(all)
- Environmental Chemistry
Cite this
}
Kinetics of Dimethylated Thioarsenicals and the Formation of Highly Toxic Dimethylmonothioarsinic Acid in Environment. / Kim, Youn Tae; Lee, Hosub; Yoon, Hye On; Woo, Nam Chil.
In: Environmental Science and Technology, Vol. 50, No. 21, 01.11.2016, p. 11637-11645.Research output: Contribution to journal › Article
TY - JOUR
T1 - Kinetics of Dimethylated Thioarsenicals and the Formation of Highly Toxic Dimethylmonothioarsinic Acid in Environment
AU - Kim, Youn Tae
AU - Lee, Hosub
AU - Yoon, Hye On
AU - Woo, Nam Chil
PY - 2016/11/1
Y1 - 2016/11/1
N2 - Dimethylmonothioarsinic acid (DMMTAV) is a highly toxic, thiolated analogue of dimethylarsinic acid (DMAV). In comparison, a further thiolated analogue, dimethyldithioarsinic acid (DMDTAV), and DMAV both exhibit lower toxicity. To understand the environmental conditions responsible for forming DMMTAV, the kinetics of DMAV thiolation are examined. The thiolation of DMAV is pH-dependent and consists of two consecutive first-order reactions under excess sulfide conditions. The first thiolation of DMAV to form DMMTAV is faster than the second one to DMDTAV. DMMTAV is therefore an intermediate. The first reaction is first-order in H2S at pH 6.0 and 20 °C; therefore, the overall reaction is second-order and the rate coefficient in this condition is 0.0780 M-1 s-1. The rate coefficient significantly decreases at pH 8.0, indicating that H2S(aq) triggers the thiolation of DMAV. The second reaction rate is significantly decreased at pH 2.5; therefore, reaction under strongly acidic conditions leads to accumulation of highly toxic DMMTAV in the early stages of thiolation. The transformation of DMDTAV to DMMTAV is catalyzed in the presence of ferric iron. Formation of DMMTAV should be considered when assessing risk posed by arsenic under sulfidic or sulfate reducing conditions.
AB - Dimethylmonothioarsinic acid (DMMTAV) is a highly toxic, thiolated analogue of dimethylarsinic acid (DMAV). In comparison, a further thiolated analogue, dimethyldithioarsinic acid (DMDTAV), and DMAV both exhibit lower toxicity. To understand the environmental conditions responsible for forming DMMTAV, the kinetics of DMAV thiolation are examined. The thiolation of DMAV is pH-dependent and consists of two consecutive first-order reactions under excess sulfide conditions. The first thiolation of DMAV to form DMMTAV is faster than the second one to DMDTAV. DMMTAV is therefore an intermediate. The first reaction is first-order in H2S at pH 6.0 and 20 °C; therefore, the overall reaction is second-order and the rate coefficient in this condition is 0.0780 M-1 s-1. The rate coefficient significantly decreases at pH 8.0, indicating that H2S(aq) triggers the thiolation of DMAV. The second reaction rate is significantly decreased at pH 2.5; therefore, reaction under strongly acidic conditions leads to accumulation of highly toxic DMMTAV in the early stages of thiolation. The transformation of DMDTAV to DMMTAV is catalyzed in the presence of ferric iron. Formation of DMMTAV should be considered when assessing risk posed by arsenic under sulfidic or sulfate reducing conditions.
UR - http://www.scopus.com/inward/record.url?scp=84994246045&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84994246045&partnerID=8YFLogxK
U2 - 10.1021/acs.est.6b02656
DO - 10.1021/acs.est.6b02656
M3 - Article
C2 - 27701855
AN - SCOPUS:84994246045
VL - 50
SP - 11637
EP - 11645
JO - Environmental Science & Technology
JF - Environmental Science & Technology
SN - 0013-936X
IS - 21
ER -