dc.contributor.author | Vudamala, K. | |
dc.contributor.author | Chakraborty, P. | |
dc.date.accessioned | 2016-03-09T09:32:06Z | |
dc.date.available | 2016-03-09T09:32:06Z | |
dc.date.issued | 2016 | |
dc.identifier.citation | Microchemical Journal, vol.126; 2016; 551-557 | |
dc.identifier.other | no | |
dc.identifier.uri | http://drs.nio.org/drs/handle/2264/4924 | |
dc.description.abstract | Competing ligand exchange method (CLEM) in conjunction with direct mercury analyzer (DMA) was found to be a useful method for kinetic speciation study of (mercury–humic acid) Hg–HA complexes in aqueous systems. Ambersep GT74 (containing a thiol functional group) was used as a suitable competing ligand for this study. The CLEM/DMA was used to estimate lability and dissociation rate constant of Hg–HA complexes in aquatic systems. Influences of pH, metal loading and varying major cation (Ca<sup>2+</sup>) concentrations on Hg–HA complexes were investigated. Concentration of dynamic Hg–HA complexes gradually increased with increasing Hg loading in the system. The dissociation rate constant (k<sub>d1</sub>) of labile Hg–HA complexes were found to vary from 4.3 × 10<sup>-3</sup> s<sup>-1</sup> to 9.2 × 10s<sup>-3</sup> s<sup>-1</sup> with increasing Hg loading from 1.0 × 10<sup>-8</sup> M to 1.42 × 10<sup>-7</sup> M. The concentrations of Hg–HA complexes with low thermodynamic stability were found to be similar at pH 4 and 5 (~ 59% and 58% of the total Hg with k<sub>d1</sub> values of ~2 × 10<sup>-1</sup> and 1.7 × 10<sup>-3</sup> s<sup>-1</sup>, respectively). The complexation of Hg with HA was found to increase with increasing pH from 4 to 7. The concentration of inert complexes (c<sub>2</sub>) with dissociation rate constant (k<sub>d2</sub>) gradually increased with increasing pH. Increasing concentration of Ca<sup>2+</sup> in the model solutions increased the concentrations of Hg–HA dynamic complexes in the system. This finding suggests that the Hg–HA bond is predominantly ionic in nature. It suggests that Ca<sup>2+</sup> ions screen out Hg<sup>2+</sup> ions from undergoing complexation reaction with HA. | |
dc.language.iso | en | |
dc.publisher | Elsevier | |
dc.relation.requires | Microchem_J_126_551.jpg | |
dc.rights | An edited version of this paper was published by Elsevier. Copyright [2016] Elsevier | |
dc.subject | AQUATIC POLLUTION | |
dc.subject | CHEMISTRY AND BIOGEOCHEMISTRY | |
dc.subject | CHEMISTRY AND BIOGEOCHEMISTRY | |
dc.title | Kinetic speciation of mercury–humate complexes in aqueous solutions by using competing ligand exchange method | |
dc.type | Journal Article | |