Reduction of mercury(II) by tropical river humic substances (Rio Negro) - Part II. Influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur)

Rocha, Júlio César; Sargentini, Ézio; Zara, Luiz Fabrício; Rosa, André Henrique; dos Santos, Ademir Bernardo; Burba, Peter

Artigo

Reduction of mercury(II) by tropical river humic substances (Rio Negro) - Part II. Influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur)

The influence of structural features of tropical river humic substances (HS) on their capability to reduce mercury(II) in aqueous solutions was studied. The HS investigated were conventionally isolated from Rio Negro water-Amazonas State/Brazil by means of the collector XAD 8. In addition, the isola...

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Autor principal:	Rocha, Júlio César
Outros Autores:	Sargentini, Ézio, Zara, Luiz Fabrício, Rosa, André Henrique, dos Santos, Ademir Bernardo, Burba, Peter
Grau:	Artigo
Idioma:	English
Publicado em:	Talanta 2020
Assuntos:	Complexation Ions Mercury (metal) Molecular Weight Ph Effects Ultrafiltration Ultraviolet Spectroscopy Volume Fraction Aromaticity Reduction Mercury Phenol Derivative Sulfur Aqueous Solution Binding Affinity Brasil Humic Substance Kinetics Molecular Size Molecular Weight Ph Potentiometry Reduction River Structure Analysis Ultrafiltration Ultraviolet Spectroscopy
Acesso em linha:	https://repositorio.inpa.gov.br/handle/1/18958

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spelling	oai:repositorio:1-18958 Reduction of mercury(II) by tropical river humic substances (Rio Negro) - Part II. Influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur) Rocha, Júlio César Sargentini, Ézio Zara, Luiz Fabrício Rosa, André Henrique dos Santos, Ademir Bernardo Burba, Peter Complexation Ions Mercury (metal) Molecular Weight Ph Effects Ultrafiltration Ultraviolet Spectroscopy Volume Fraction Aromaticity Reduction Mercury Phenol Derivative Sulfur Aqueous Solution Binding Affinity Brasil Humic Substance Kinetics Molecular Size Molecular Weight Ph Potentiometry Reduction River Structure Analysis Ultrafiltration Ultraviolet Spectroscopy The influence of structural features of tropical river humic substances (HS) on their capability to reduce mercury(II) in aqueous solutions was studied. The HS investigated were conventionally isolated from Rio Negro water-Amazonas State/Brazil by means of the collector XAD 8. In addition, the isolated HS were on-line fractionated by tangential-flow multistage ultrafiltration (nominal molecular-weight cut-offs: 100, 50, 30, 10, 5 kDa) and characterized by potentiometry and UV/VIS spectroscopy. The reduction of Hg(II) ions to elemental Hg by size-fractions of Rio Negro HS was assessed by cold-vapor AAS (CVAAS). UV/VIS spectrometry revealed that the fractions of high molecular-size (F1 > 100 kDa and F2: 50-100 kDa) have a higher aromaticity compared to the fractions of small molecular-size (F5: 5-10 kDa, F6: < 5 kDa). In contrast, the potentiometric study showed different concentration of functional groups in the studied HS fractions. The reduction of Hg(II) by aquatic HS fractions at pH 5 proceeded in two steps (I, II) of slow first order kinetics (t1/2 of I: 160 min, t 1/2 of II: 300 min) weakly influenced by the molecular-size, in contrast to the differing degree of Hg(II) reduction (F5 > F 2 > > F1 > F3 > F4 > > F6). Accordingly, Hg(II) ions were preferably reduced by HS molecules having a relatively high ratio of phenolic/carboxylic groups and a small concentration of sulfur. From these results a complex 'competition' between reduction and complexation of mercury(II) by aquatic HS occurring in tropical rivers such as the Rio Negro can be suggested. © 2003 Elsevier B.V. All rights reserved. 2020-06-15T22:04:11Z 2020-06-15T22:04:11Z 2003 Artigo https://repositorio.inpa.gov.br/handle/1/18958 10.1016/S0039-9140(03)00351-5 en Volume 61, Número 5, Pags. 699-707 Restrito Talanta
institution	Instituto Nacional de Pesquisas da Amazônia - Repositório Institucional
collection	INPA-RI
language	English
topic	Complexation Ions Mercury (metal) Molecular Weight Ph Effects Ultrafiltration Ultraviolet Spectroscopy Volume Fraction Aromaticity Reduction Mercury Phenol Derivative Sulfur Aqueous Solution Binding Affinity Brasil Humic Substance Kinetics Molecular Size Molecular Weight Ph Potentiometry Reduction River Structure Analysis Ultrafiltration Ultraviolet Spectroscopy
spellingShingle	Complexation Ions Mercury (metal) Molecular Weight Ph Effects Ultrafiltration Ultraviolet Spectroscopy Volume Fraction Aromaticity Reduction Mercury Phenol Derivative Sulfur Aqueous Solution Binding Affinity Brasil Humic Substance Kinetics Molecular Size Molecular Weight Ph Potentiometry Reduction River Structure Analysis Ultrafiltration Ultraviolet Spectroscopy Rocha, Júlio César Reduction of mercury(II) by tropical river humic substances (Rio Negro) - Part II. Influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur)
topic_facet	Complexation Ions Mercury (metal) Molecular Weight Ph Effects Ultrafiltration Ultraviolet Spectroscopy Volume Fraction Aromaticity Reduction Mercury Phenol Derivative Sulfur Aqueous Solution Binding Affinity Brasil Humic Substance Kinetics Molecular Size Molecular Weight Ph Potentiometry Reduction River Structure Analysis Ultrafiltration Ultraviolet Spectroscopy
description	The influence of structural features of tropical river humic substances (HS) on their capability to reduce mercury(II) in aqueous solutions was studied. The HS investigated were conventionally isolated from Rio Negro water-Amazonas State/Brazil by means of the collector XAD 8. In addition, the isolated HS were on-line fractionated by tangential-flow multistage ultrafiltration (nominal molecular-weight cut-offs: 100, 50, 30, 10, 5 kDa) and characterized by potentiometry and UV/VIS spectroscopy. The reduction of Hg(II) ions to elemental Hg by size-fractions of Rio Negro HS was assessed by cold-vapor AAS (CVAAS). UV/VIS spectrometry revealed that the fractions of high molecular-size (F1 > 100 kDa and F2: 50-100 kDa) have a higher aromaticity compared to the fractions of small molecular-size (F5: 5-10 kDa, F6: < 5 kDa). In contrast, the potentiometric study showed different concentration of functional groups in the studied HS fractions. The reduction of Hg(II) by aquatic HS fractions at pH 5 proceeded in two steps (I, II) of slow first order kinetics (t1/2 of I: 160 min, t 1/2 of II: 300 min) weakly influenced by the molecular-size, in contrast to the differing degree of Hg(II) reduction (F5 > F 2 > > F1 > F3 > F4 > > F6). Accordingly, Hg(II) ions were preferably reduced by HS molecules having a relatively high ratio of phenolic/carboxylic groups and a small concentration of sulfur. From these results a complex 'competition' between reduction and complexation of mercury(II) by aquatic HS occurring in tropical rivers such as the Rio Negro can be suggested. © 2003 Elsevier B.V. All rights reserved.
format	Artigo
author	Rocha, Júlio César
author2	Sargentini, Ézio Zara, Luiz Fabrício Rosa, André Henrique dos Santos, Ademir Bernardo Burba, Peter
author2Str	Sargentini, Ézio Zara, Luiz Fabrício Rosa, André Henrique dos Santos, Ademir Bernardo Burba, Peter
title	Reduction of mercury(II) by tropical river humic substances (Rio Negro) - Part II. Influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur)
title_short	Reduction of mercury(II) by tropical river humic substances (Rio Negro) - Part II. Influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur)
title_full	Reduction of mercury(II) by tropical river humic substances (Rio Negro) - Part II. Influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur)
title_fullStr	Reduction of mercury(II) by tropical river humic substances (Rio Negro) - Part II. Influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur)
title_full_unstemmed	Reduction of mercury(II) by tropical river humic substances (Rio Negro) - Part II. Influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur)
title_sort	reduction of mercury(ii) by tropical river humic substances (rio negro) - part ii. influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur)
publisher	Talanta
publishDate	2020
url	https://repositorio.inpa.gov.br/handle/1/18958
_version_	1787142973597679616
score	11.755432

Reduction of mercury(II) by tropical river humic substances (Rio Negro) - Part II. Influence of structural features (molecular size, aromaticity, phenolic groups, organically bound sulfur)

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