Electromembrane extraction and electrochemical measurement system for heavy metal ions detection in aquatic environmental samples

Water contamination is a worldwide problem which deserves attention due to its negative impact on ecosystem, human health as well as economic growth. Heavy metals are a group of the pollutants that have received particular attention due to their high toxicity even at concentration as low as parts pe...

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Main Author:	Kunashegaran, Hamsawahini
Format:	Thesis
Language:	English
Published:	2018
Subjects:	QD Chemistry
Online Access:	http://eprints.utm.my/id/eprint/81010/1/HamsawahiniKunashegaranPFS2018.pdf
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spelling	my-utm-ep.810102019-07-24T00:14:25Z Electromembrane extraction and electrochemical measurement system for heavy metal ions detection in aquatic environmental samples 2018-08 Kunashegaran, Hamsawahini QD Chemistry Water contamination is a worldwide problem which deserves attention due to its negative impact on ecosystem, human health as well as economic growth. Heavy metals are a group of the pollutants that have received particular attention due to their high toxicity even at concentration as low as parts per billion (ppb). Technology advancement in the field of separation and detection of heavy metals has introduced sensitive and selective analytical instruments for real aquatic environmental samples. However, real sample matrices can reduce the quality of results. In modern analytical chemistry, there is a high demand for accurate quantification of trace and ultra-trace of heavy metals from real aqueous samples. In the present study, electromembrane extraction (EME) and electrochemical techniques were combined to develop effective electrodes which can separate, pre-concentrate and determine heavy metals such as Pb(II), Cr(VI) and Cd(II) in real aqueous samples. Electrochemically reduced graphene oxide-graphite reinforced carbon (ErGO-GRC) was utilised in conjunction with square wave anodic stripping voltammetry (SWASV) for the determination of Pb(II). Meanwhile, selective and sensitive determinations of Cr(VI) was carried out using ex-situ prepared nafion-coated antimony film on graphite reinforced carbon (NSbFE-GRC) by square wave adsorptive stripping voltammetry (SWAdSV) in the presence of diethyltriamine pentacetic acid (DTPA). Ex-situ prepared NSbFE-GRC was also used for simultaneous determination of Pb(II) and Cd(II) by SWASV. Simple polyvinylidene fluoride (PVDF) flat sheet membranes were synthesised and characterised in order to combine these developed electrochemical techniques with EME. Heavy metals were extracted from an aqueous sample solution into an acidic acceptor phase in the lumen of a PVDF membrane bag by the application of voltage across the supported liquid membrane (SLM), consisting of organic solvent and complexing carriers. Parameters affecting the EME were optimised for heavy metals. The PVDF–ErGO–GRC electrode system attained enrichment factors of 40 times and 80% extraction with relative standard deviation (n = 5) of 8.3% for Pb(II). Good linearity in the range of 0.25-2 nM was obtained with correlation coefficient of 0.999. The Pb(II) ions detection limit of PVDF–ErGO–GRC electrode was 0.09 nM. Meanwhile, the PVDF–NSbFE–GRC system attained enrichment factors of 86.6 times, 95.6% extraction, and good linearity in the range of 10-60 pM with correlation coefficient of 0.9933. Furthermore, the limit of Cr(VI) detection was found to be around 0.83 pM for the developed PVDF–NSbFE–GRC electrode. On the other hand, the PVDF–NSbFE–GRC was able to attain enrichment factors of 49.3 and 68.4 times, 82.6% and 114.0% extractions, and good linearity ranging from 2 to 10 pM with correlation coefficients of 0.9953 and 0.9883 for Pb(II) and Cd(II), respectively. Furthermore, the limits of detection for Pb(II) and Cd(II) were found to be around 0.65 pM and 0.60 pM, respectively. A chargeable battery operated portable EME system was developed for quantitative determination of heavy metals. The newly developed single setup electrochemical system was applied to the analysis of real aqueous samples such as tap water, industrial waste water, river water and sea water, and it was able to extract with percentage of extraction in the range of 78.7 -103.0% compared to commercially available direct current power supply. 2018-08 Thesis http://eprints.utm.my/id/eprint/81010/ http://eprints.utm.my/id/eprint/81010/1/HamsawahiniKunashegaranPFS2018.pdf application/pdf en public http://dms.library.utm.my:8080/vital/access/manager/Repository/vital:125077 phd doctoral Universiti Teknologi Malaysia, Faculty of Science Faculty of Science
institution	Universiti Teknologi Malaysia
collection	UTM Institutional Repository
language	English
topic	QD Chemistry
spellingShingle	QD Chemistry Kunashegaran, Hamsawahini Electromembrane extraction and electrochemical measurement system for heavy metal ions detection in aquatic environmental samples
description	Water contamination is a worldwide problem which deserves attention due to its negative impact on ecosystem, human health as well as economic growth. Heavy metals are a group of the pollutants that have received particular attention due to their high toxicity even at concentration as low as parts per billion (ppb). Technology advancement in the field of separation and detection of heavy metals has introduced sensitive and selective analytical instruments for real aquatic environmental samples. However, real sample matrices can reduce the quality of results. In modern analytical chemistry, there is a high demand for accurate quantification of trace and ultra-trace of heavy metals from real aqueous samples. In the present study, electromembrane extraction (EME) and electrochemical techniques were combined to develop effective electrodes which can separate, pre-concentrate and determine heavy metals such as Pb(II), Cr(VI) and Cd(II) in real aqueous samples. Electrochemically reduced graphene oxide-graphite reinforced carbon (ErGO-GRC) was utilised in conjunction with square wave anodic stripping voltammetry (SWASV) for the determination of Pb(II). Meanwhile, selective and sensitive determinations of Cr(VI) was carried out using ex-situ prepared nafion-coated antimony film on graphite reinforced carbon (NSbFE-GRC) by square wave adsorptive stripping voltammetry (SWAdSV) in the presence of diethyltriamine pentacetic acid (DTPA). Ex-situ prepared NSbFE-GRC was also used for simultaneous determination of Pb(II) and Cd(II) by SWASV. Simple polyvinylidene fluoride (PVDF) flat sheet membranes were synthesised and characterised in order to combine these developed electrochemical techniques with EME. Heavy metals were extracted from an aqueous sample solution into an acidic acceptor phase in the lumen of a PVDF membrane bag by the application of voltage across the supported liquid membrane (SLM), consisting of organic solvent and complexing carriers. Parameters affecting the EME were optimised for heavy metals. The PVDF–ErGO–GRC electrode system attained enrichment factors of 40 times and 80% extraction with relative standard deviation (n = 5) of 8.3% for Pb(II). Good linearity in the range of 0.25-2 nM was obtained with correlation coefficient of 0.999. The Pb(II) ions detection limit of PVDF–ErGO–GRC electrode was 0.09 nM. Meanwhile, the PVDF–NSbFE–GRC system attained enrichment factors of 86.6 times, 95.6% extraction, and good linearity in the range of 10-60 pM with correlation coefficient of 0.9933. Furthermore, the limit of Cr(VI) detection was found to be around 0.83 pM for the developed PVDF–NSbFE–GRC electrode. On the other hand, the PVDF–NSbFE–GRC was able to attain enrichment factors of 49.3 and 68.4 times, 82.6% and 114.0% extractions, and good linearity ranging from 2 to 10 pM with correlation coefficients of 0.9953 and 0.9883 for Pb(II) and Cd(II), respectively. Furthermore, the limits of detection for Pb(II) and Cd(II) were found to be around 0.65 pM and 0.60 pM, respectively. A chargeable battery operated portable EME system was developed for quantitative determination of heavy metals. The newly developed single setup electrochemical system was applied to the analysis of real aqueous samples such as tap water, industrial waste water, river water and sea water, and it was able to extract with percentage of extraction in the range of 78.7 -103.0% compared to commercially available direct current power supply.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Kunashegaran, Hamsawahini
author_facet	Kunashegaran, Hamsawahini
author_sort	Kunashegaran, Hamsawahini
title	Electromembrane extraction and electrochemical measurement system for heavy metal ions detection in aquatic environmental samples
title_short	Electromembrane extraction and electrochemical measurement system for heavy metal ions detection in aquatic environmental samples
title_full	Electromembrane extraction and electrochemical measurement system for heavy metal ions detection in aquatic environmental samples
title_fullStr	Electromembrane extraction and electrochemical measurement system for heavy metal ions detection in aquatic environmental samples
title_full_unstemmed	Electromembrane extraction and electrochemical measurement system for heavy metal ions detection in aquatic environmental samples
title_sort	electromembrane extraction and electrochemical measurement system for heavy metal ions detection in aquatic environmental samples
granting_institution	Universiti Teknologi Malaysia, Faculty of Science
granting_department	Faculty of Science
publishDate	2018
url	http://eprints.utm.my/id/eprint/81010/1/HamsawahiniKunashegaranPFS2018.pdf
_version_	1747818292132708352

Electromembrane extraction and electrochemical measurement system for heavy metal ions detection in aquatic environmental samples

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