Speciation and extraction of mercury has been studied using cloud point extraction of polyethylene glycol (PEG). A solution of PEG itself is reported to form cloud at a considerably high temperature which is unfavorable for the extraction and separation of volatile analytes. Different inorganic salt solutions (Na2SO4, NaH2PO4, NaCl, NaOAc) when used as additives were found to lower the cloud point temperature of PEG (#6000) effectively. The lowest temperature for cloud formation was observed at 35 °C with 0.8 M Na2SO4. The cloud so formed was found suitable to discriminate between inorganic and organic mercury species. 1-(2-pyridylazo)-2-napthol (PAN) was used for spectrophotometric detection of inorganic and organic mercury. Confocal microscopic images and zeta potential values reveal the actual interactions of the inorganic Hg species with the organized PEG micelles in aqueous medium. Environmental samples were also analyzed using the present method. © 2016 Elsevier Ltd.

KAMALIKA SEN

Chemistry

P SAMADDAR

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Journal of Environmental Chemical Engineering

Grafting of guar gum (GG) and in situ strategic attachment of acrylamidosodiumpropanoate (ASP) via solution polymerization of acrylamide (AM) and sodium acrylate (SA) resulted in the synthesis of a sustainable GG-g-(AM-co-SA-co-ASP)/GGAMSAASP interpenetrating polymer network (IPN)-based smart superadsorbent with excellent physicochemical properties and reusability, through systematic optimization by response surface methodology (RSM) for removal of methyl violet (MV) and/or Hg(II). The relative effects of SA/AM ratios, in situ allocation of ASP, grafting of GG into the AMSAASP terpolymer, ligand-selective superadsorption mechanism and relative microstructural changes in individually/synergistically-adsorbed MV−/Hg(II)−/Hg(II)−MV−GGAMSAASPs were determined by extensive analyses using Fourier transform infrared (FTIR), proton nuclear magnetic resonance, ultraviolet−visible (UV−vis), and O 1s-/N 1s-/C 1s-/Hg 4f7/2,5/2-X-ray photoelectron spectroscopies, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, field emission scanning electron microscopy, and energy-dispersive spectroscopy and were supported by % gel content, pHPZC, and % graft ratio. The ionic/covalent-bonding, monodentate, bidentate bridging, and bidentate chelating coordination between GGAMSAASPs and Hg(II), and MV+−Hg(II) bonding were rationalized by FTIR, UV−vis, fitment of kinetics data to the pseudo-second-order model, and thermodynamic parameters. The maximum adsorption capacities of 49.12 and 53.28 mg g−1 were determined for Hg(II) and MV, respectively, under optimized conditions. © 2018 American Chemical Society.

Fulltext

ACS Omega

Guar gum-grafted terpolymer hydrogels for ligand-selective individual and synergistic adsorption: Effect of comonomer composition

The environmentally benign extraction systems like aqueous biphasic system (ABS) and cloud point extraction (CPE) techniques are well exploited for their applications in elemental speciation analysis. In this article we have studied the extraction possibility of different Zn species using ABS and CPE. The extractions are studied at trace concentration levels in the presence and absence of different interfering cations and anions to find the possibility to preconcentrate Zn in the presence of other elements. It has been observed that using CPE, a complete extraction of Zn-PAN is possible with Cu(II) as a potential interfering ion. Using ABS, ~82% extraction of Zn as Zn-insulin complex is possible with no considerable interference from the associated metal ions. However, the anions like PO43-, SCN- and NO2- ions do interfere. Finally, the clouds of the CPE were taken for confocal microscopy after dissolution in suitable media. The images demonstrate the mechanism of micellization of different Zn species. The nanometer sized vesicles with the Zn species incorporated in it indicates a stronger extraction possibility of the CPE than ABS. The results are indicative of the methodology to be chosen for Zn extraction as per the need of the analyst. © 2014 The Korean Society of Industrial and Engineering Chemistry.

Journal of Industrial and Engineering Chemistry

Species dependent sustainable preconcentration of zinc: Possible aspects of ABS and CPE

Trace elements are gaining increasing attention of scientists working in various analytical fields. Presence or absence of a trace element in a system seriously modifies its intrinsic behavior. Cloud point extraction (CPE) is an upcoming technology to preconcentrate and separate many of the trace elements from different chemical and biological systems. The system is sustainable as it involves benign extractants like surfactants and that too at low concentrations at slightly elevated temperatures to form clouds that separate out from the bulk solution. In addition, the extraction behavior of many elements depends on its chemical species. Keeping in view the need to summarize the research encompassing this technique, many review articles were published which cover a selection of the literature published on this topic over several time spans. A myriad of various technological developments has been reported by several workers. These developments have prompted us to revisit the CP technology with a better understanding of its detection, mechanism and extension to species dependent extraction behavior with regard to the state of art determination of trace metals in our day to day applications. The present article summarizes mainly the results of trace metal preconcentration using CP methodology from different practical samples with an insight to the probable mechanism and speciation involved from 2006 onwards. © 2013 The Korean Society of Industrial and Engineering Chemistry.

Cloud point extraction: A sustainable method of elemental preconcentration and speciation

Fluorescence in poly(ethylene glycol) (PEGs 400-12000) solutions is reported here for the first time. PEG solutions form a vesicular organization with the hydrophilic groups attached at both ends which arrange themselves beyond a particular concentration and offer electron-dense regions at the center of the vesicle. These vesicles provide an inherent site for fluorescence generation in PEG solutions. Fluorescence emission was observed at ∼380 nm with an excitation wavelength of 300 nm. PEG of molecular weight 6000 was found to show maximum emission intensity at a particular concentration. The formation of PEG vesicles (∼1 nm size) was confirmed by dynamic light scattering (DLS) and confocal laser microscopy. On addition of metal ions the polymeric vesicle breaks up to monomeric PEG, and hence, the fluorescence intensity decreases with a red shift. Fluorescence lifetime measurements indicate the nature of complexation of the metals with PEG. Since PEGs are used as one of the phases in aqueous biphasic systems (ABS) of liquid-liquid extractions, the nature of the fluorescence emission spectrum of the PEG phase after extraction was studied. Metal extraction in the PEG-rich phase of an ABS leads to quenching of fluorescence in PEG. © 2012 American Chemical Society.

Analytical Chemistry

Poly(ethylene glycol) vesicles: Self-assembled site for luminescence generation

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy

Simultaneous preconcentration of copper and mercury in water samples by cloud point extraction and their determination by inductively coupled plasma atomic emission spectrometry

Journal	Data powered by TypesetJournal of Environmental Chemical Engineering
Publisher	Data powered by TypesetElsevier Ltd
ISSN	2213-3437