Fluorescent Resin-Assisted Extraction for Selective Separation and

Article pubs.acs.org/jced

Fluorescent Resin-Assisted Extraction for Selective Separation and Preconcentration of Mercury(II) and Its Online Detection Bhavya Srivastava, Dipika Roy, Rimi Sarkar, Sneha Mondal, Mousumi Chatterjee, Siddthartha Banerjee, and Bhabatosh Mandal* Analytical Laboratory, Department of Chemistry, Visva-Bharati, Santiniketan 731235, India S Supporting Information *

ABSTRACT: Dimethyldichlorosilane (DMDCS) driven silane coupling is enabled by productive immobilization of an azo-dye to inorganic carrier through m-nitroaniline as a bridging component. The material has been utilized for the selective sample cleanup of zinc(II), cadmium(II), and mercury(II), respectively, extracted as [Zn5(OH)6(H2O)2]4+, [Cd4(OH)4(H2O)3]4+, and [Hg4(OH)3(H2O)2]5+. The corresponding luminescent nanomaterial was used for selective detection of mercury(II) at trace level (LOD ≥ 0.04 × 10−5 M) amid a matrix of possible interferences. Breakthrough capacity (BTC) and preconcentration factor (PF) for the respective metal ions (BTCZinc(II), 600; BTCCadmium(II), 460; BTCMercury(II), 540 μM g−1; and PFZinc(II), 197; PFCadmium(II), 148; PFMercury(II), 145) were found to be excellent. Sequential separation of zinc(II), cadmium(II), and mercury(II) was achieved by employing selective eluents (mineral acids of very low concentration, 5 × 103 μM). BTC (530 ± 70 μM g−1) was found to be the product of the amount of extractor frontier orbitals (132 μM g−1) and polynuclear state of sorbed species, x (i.e., BTC = {amount of HOMO}× x; x = 4 for cadmium(II), mercury(II); and x = 5 for zinc(II)). Along with these analytical qualities, ease of synthesis, high level of reusability (≤2700 cycles @ 95% exchange capacity), and chemical stability (post treatment BTC with 8 M HNO3, 8 M HCl, and 5 M H2SO4 was ≤95%) is an insignia of the material.

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INTRODUCTION Mercury is widely used in various instruments and industries as well. Considerable amounts of mercury along with its congeners enter into the habitat from both natural (like volcanic eruptions, geothermal sources, and topsoil enriched in mercury) and anthropogenic (metallurgy industries, combustion of coal, and automobiles) accomplishments.1 Amidst several other coexisting congeners, mercury with its unidirectional movement enters continuously at the super selective binding sites in living organisms (LO). This super selective binding ability helps to overcome the matrix effect and trace level mercury surpasses the risk level (fatal dose) in LO2,3 by bioaccumulation and biomagnifications. Thus, it is imperative to develop reliable methods for the detection, estimation, and recovery/removal of mercury at trace level from environmental and biological samples. In principle, the conventional approaches, viz., atomic absorption spectroscopy (AAS) and inductively coupled plasma-mass (ICP-MS), can measure the total Hg content with a satisfying sensitivity.4 However, direct instrumental detection/determination in those real samples is a difficult task; they require complicated, multistep sample preparation and sophisticated instruments, which all limit the applications of these methods for Hg detection.5 The main © 2017 American Chemical Society

hindrance comes from the complexity of the matrix (i.e., along with the desired analyte coexisting congeners enter into the instrumental recorder) where the analyte is present at an untraceable level for the detector. Consequently, a proper cleanup for analyte containing mercury6 is absolutely necessary. The problem is conventionally tackled by the commonly used techniques like cloud point extraction,7 adsorption,8−10 liquid− liquid extraction,11,12 liquid chromatography,13,14 ion-exchange,15 resin chelation,16,17 foam-flotation,18 and solidphase extraction (SPE) methods.19,20 SPE technique has greater applicability over the traditional solvent extraction process.21,22 It requires an efficient adsorbing material, usually the chelating ligands, being present on an inert support interacting with metal ions selectively. A variety of ligands (having sulfur as ligating sites), viz., pyrrolidine-dithiocarbamateAPDC,23 diethyldithiocarbamate,24 sulfydryl,25 2-mercaptoethanol,25 and dithizone26 have been used for the extraction of mercury(II) species on C18 cartridges (as an inert support). However, silica gel (SG) is a widely acceptable Received: February 28, 2017 Accepted: June 9, 2017 Published: June 23, 2017 2350

DOI: 10.1021/acs.jced.7b00224 J. Chem. Eng. Data 2017, 62, 2350−2361

Journal of Chemical & Engineering Data

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Scheme 1. Preparation of FSG Followed by Ligand (EBT) Immobilization (Can Be Assessed with Naked Eye as Deep Red Mass)

particularly in mercury sensing. The highly concerned toxicant is receiving enormous interest in the scientific community because of its duplicitous character (beside its utilities in industries and instruments, it also has been accused of several human pathologies2,3). Ipso facto, along with the sample cleanup, luminescent properties of the synthesized nanomaterial are also being applied here for online detection of mercury at trace level.

ideal inert support for ligands, as it does not swell or strain, possesses sufficient mechanical strength, and also withstands heat treatment.27−32 Covalently bound immobilized chelating ligands on SG forming SPE materials are attractive because of their appreciable sorption capacity, unique selectivity (low matrix effect), high level of preconcentration factor (PF), ecofriendliness, and significant reusability.33−35 Following Weetall36−39 and Hill,40 Sugawara et al.41 in their pioneering works synthesized a controlled-pore-glass-oxine immobilized phase (CPG-8-HQ) for SPE of nickel(II), cobalt(II), iron(III), copper(II), zirconium(IV), titanium(IV), vanadium(V), and aluminum(III). Since then, a considerable amount of work has been done to optimize the immobilization of various chelating ligands on SG.42−48 Here, in all cases, Weetall36−39−Hill40 was followed; in this process, CPG was first refluxed overnight with 10% γ-aminopropyltriethoxysilane in toluene. Subsequently, the cleaned alkylamine glass was treated with p-nitrobenzoyl chloride in chloroform having triethylamine (5%). The nitro compound was converted to its amine derivative by boiling the mass with aqueous sodium dithionite. After its diazotization, the glass was coupled with 0.25% (w/v) of enzyme/chelating ligand solution at 0 °C. Polyakov-Rogovin49 coupled TashiroShimura50 reaction process was also found to be lengthy and complicated, and in fact, it needs a wide range of toxic chemicals (viz., SOCl2, pyridine, DMF, dioxin, etc.). As an outcome of our previous work relating to instantaneous attachment of metal chelators, viz., Xylenol Orange, PAN to SG via a new silane coupling agent (dimethyldichlorosilane)51,52 forming immobilized chelate phases encourages the present authors to develop EBTimmobilized-SG SPE material (EBT@R-{SiO2}n; where R stands for p-NN−C6H4−NH−SiCl2−O−) for selective sample cleanup of mercury(II) from its congeners. Dimethyldichlorosilane simultaneously couples SG and p-nitroaniline and quantitatively produces a stable nitro compound, {SiO2}n−O− Si(Me)2−NH−C6H4−NO2. Subsequently, it is reduced to an arylamine, required to immobilize EBT via diazo coupling reaction. The first step is an instantaneous reaction, needs no refluxing, filtration, and all other Weetall-Hill conditions;36−40 and it replaces the first and second steps of Weetall-Hill36−40 by a one-pot single-step reaction. Along with the procedural ease and rapidity, its composition, DFT computed 3-D structure,33,34 and molecular mass,30 in the present investigation the analytical performance (i.e., quantification and placement of frontier orbitals, FO) and utilities of these quantified FO for sample cleanup of mercury merit mention. Although several investigators are working with luminescent gold-HEPPSO nanocomposites,53 oligonucleotides,53 covalent organic frameworks (COFs),17,54 electrochemical biosensor,55 supramolecular network,56 and metal−organic frameworks57,58 for their potential applications in catalysis, gas storage, drug delivery, and sensing; inorganic−organic frameworks are indeed scanty,

2. EXPERIMENTAL SECTION 2.1. Instrumentation for Morphology and Structural Characterization. See Supporting Information (File S1). 2.2. Reagents and Chemicals. See Supporting Information (File S2). 2.3. Preparation of the Extractor (FSG-EBT). The preparative methodology has already been reported in our earlier article30 (Scheme 1) (see Supporting Information File S3). 2.4. 3-D Structural Optimization of the Synthesized Extractor. (see Supporting Information (File S4). 2.5. Analytical Applicability of the Extractor. 2.5.1. Detection of Mercury(II). Fluorescence spectra (λexcitation: 330 nm and λemission: 350−550 nm) of nano-FSG-EBT (fluorophore) in DMSO at different concentrations (0.0625 × 10−7 to 0.01 × 10−5 M) were recorded on PerkinElmer LS-55-spectrophotometer. Mercury(II) sensing abilities of the fluorophore at its fixed concentration, 0.01 × 10−5 M, were systematically studied over the mercury(II) concentration 0.02 × 10−5 to 0.5 × 10−5 M. 2.5.2. Systematic Investigations for Sample Cleanup of Mercury(II). Monitoring and measurement of mercury(II) amidst coexisting congeners like zinc(II), cadmium(II), and several other ionic interferences (i.e., in real samples) at trace level requires proper sample cleanup. It is effected by two consecutive steps: (1) in an appropriate selective condition, mercury(II) is allowed to be sorbed on the sorbent from its large sample size (mL) of lower level concentration; and (2) followed by a selective elution condition, mercury(II) is allowed to be desorbed with an eluent of minimum volume (mL) to retrieve the analyte at its higher concentration. Sorption efficiency is a function of system variables, viz., initial volume, concentration, pH, and temperature and contact time of analyte solution. Systematic studies on each variable to have optimum values for best sorption efficiency toward mercury(II) and its congeners (zinc(II), cadmium(II)) were done by both batch and column-adsorption techniques. 2.5.3. Batch Adsorption Experiments. In order to optimize the time variable for kinetic studies, 0.1 g resin was allowed to equilibrate with 50 mL metal ion solutions (1.05 × 103 μM) for time periods ranging from 4 to 20 min, with a 2 min increment interval at 27 °C and constant pH (4.0 for zinc(II), 6.5 for cadmium(II), and 2.5 for mercury(II)). On the other hand, to 2351



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of eluents, viz., 5 × 103 μM HNO3, 5 × 103 μM HCl, and 5 × 103 μM H2SO4, and were determined complexometrically.59 2.5.4.2. Matrix Effect on the Extraction of Zinc(II), Cadmium(II), and Mercury(II). Real sample analysis sought a recommendation for systematic studies on sorption, required urgently to scrutinize the interferences of various electrolytes at their natural contamination concentration (50−250 mM). So, 50−1200 mL (40 mM) of an analyte (viz., zinc(II), cadmium(II), mercury(II)) solution amidst common electrolytes (viz., Na(I)/K(I) salts of chloride, fluoride, bromide, nitrate, sulfate, phosphate, acetate, and Ca(II)/Mg(II) salts of chloride) (50−250 mM) was passed through the exchanger at recommended sorption-pH (4.0−5.0 for zinc(II), 6.0−6.5 for cadmium(II), and pH 2.0−2.5 for mercury(II)) to accomplish any real analysis wherever it comes. 2.5.4.3. Breakthrough Capacity (BTC) of the Extractor for Zinc(II), Cadmium(II), and Mercury(II). At an optimum sorption condition, a particular analyte solution (40 mM) traveled through the adsorbent continuously until the column exit was found to contain 10% that of the influent. A plot of the ratio Ceff against the influent volume (where Ceff is the effluent

carry out the systematic investigations on sorption isotherms, 0.1 g dry extractor in 50 mL analyte solution (viz., zinc(II), cadmium(II), and mercury(II)) at different initial concentrations (Ci = 1.05 × 103 to 9 × 103 μM) were held with constant shaking (150−200 rpm: at which the entire surface area comes into contact with metal ions throughout the investigations) for 15 min, sufficient to reach equilibrium. Influence of temperature on adsorption efficiency was studied at various temperatures (298−333 K). From Ce (equilibrium concentration: μM) and qe (amount adsorbed on the sorbent surface at equilibrium: μM g−1; eq 1) the applicability of Langmuir (eq 2) and Freundlich equilibrium isotherms33,34 (eq 3) was examined.

qe =

(C i − Ce) × V m

(1)

Here, Ci and Ce are the concentrations at its initial and equilibrium state; V is the analyte volume (mL) and m (g) is the mass of sorbent. Langmuir isotherm linear regression Ce C 1 = + e qe Q 0b Q0

(2)

Linear regression of Freundlich isotherm ⎛1⎞ log qe = log KF + ⎜ ⎟log Ce ⎝n⎠

(3)

C0

concentrations (mM)) was drawn to have the breakthrough volume, V10% (the required influent volume for which the effluent contain 10% of original amount (mM)). BTC was CV computed using the formula, BTC = 0 10% , where C0 and W W are, respectively, the influent concentration (mM) and mass (g) of the extractor. 2.5.4.4. Elution Study. Systematic investigations were carried out on the stripping performance of zinc(II), cadmium(II), and mercury(II) with a variety of eluents (viz., HCl, HNO3, HClO4, HNO3, and CH3COOH at their diverse strengths 1.00 × 103 to 500 × 103 μM) to achieve the highest preconcentration factor,

where Q0 is the maximum monolayer sorption capacity (μM g−1) and b (Langmuir constant) is a measure of binding energy (L μM−1). On the other hand, KF and 1/n are the Freundlich constants, respectively describing the adsorption capacity and adsorption intensity. The parameter “n” signifies the affinity of the sorbent-surface for the adsorbate. 2.5.4. Studies on Column Extraction. Batch adsorption studies required continuous shaking and repetitive filtration in both sorption and desorption steps to retrieve the analyte in its cleaned and concentration-enriched state. However, in column chromatograhy, the adsorbent column itself acts as efficiently as the filter bed. An analyte is retrieved in concentration-enriched purified form through selective separation and preconcentration.35,36 2.5.4.1. Optimum Condition for Selective Extraction of Zinc(II), Cadmium(II), and Mercury(II). In aqueous solution these coexisting congeners exist as different ionic species which are pH dependent.37 It should also be noted that sorption is species dependent.34,35 Consequently, systematic investigations were made to find out the effect of solution pH on the extraction process. The pH 2.5−7.5 of both the column (1 g dry exchanger; bed height: 2.5−3.0 cm) and the analyte solution (40 mM) was adjusted using hexamine buffer. An aliquot (2 mL) containing an analyte (viz., zinc(II), cadmium(II), and mercury(II)) was passed (at a flow-rate of 5 mL min−1 at 27 °C) through the column to assess the pH−extraction relationship. A comprehensive study on the effect of solution pH on ion conductance was also executed over the pH range 2.5−6.5 to assess the pH−ion conductance−extraction correlation. These studies have prompted the present authors to assess the selectivity of the extractor for specific metal ion species. After extraction, zinc(II), cadmium(II), and mercury(II) were, respectively, stripped with minimum volume (4 mL)

PF (PF =

Vsample Veluent

× Recovery(%)). Eluted metal ions were

determined complexometrically.38 2.5.4.5. Optimization of Preconcentration Factor (PF). Preconcentration is an outcome of two consecutive processes (selective sorption of an analyte from large influent sample volume, Vi, and its desorption with an eluent of minimum volume, Vf) of sample cleanup (section 2.4). Mathematically, preconcentration factor (PF) is represented as a ratio of initial concentration to final concentration of an analyte (eq 4). Due to volume effect,29 recoveries of any analyte gradually declined along with increase in initial analyte volume, Vi, and so, the final V ×C concentration can be expressed as Cf = i V i × recovery(%) f

PF =

Cf Ci

⎤ ⎡V PF = ⎢ i × recovery(%)⎥ ⎦ ⎣ Vf

(4)

where Ci is the influent sample concentration. For a fixed minimum eluent volume (Vf), along with the increase in initial sample volume (Vi) the first term ( Vi ) of PF Vf

(eq 7) increases linearly while the second term (recovery %) decreases gradually. Therefore, an influent of varying sample size (Vi = 50−1200 mL) containing a fixed amount (40 μM) of an analyte (viz., zinc(II), cadmium(II), and mercury(II)) was passed through the column at its optimum sorption conditions; subsequently, metal ions were stripped with different acids at their minimum volume (Vf = 4 mL) to determine optimized PF. 2352



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Figure 1. (a) SEM; (b) TEM; (c) SAED micrographs of FSG-EBT resin; (d) 3-D structure of FSG-EBT; (e) spatially separated frontier orbitals (HOMO and LUMO); (f) HOMO: metal ion species 1:1 ion pair complex.

Figure 2. Florescence spectra of both (a) nano-FSG-EBT and (b) nano-FSG-EBT (0.01 × 10−5 M) containing different concentrations of mercury(II) (0.02 × 10−5 to 0.5 × 10−5 M) amidst common contaminants (viz., Cl−, F−, Br−, NO3−, SO42−, PO43−, and CH3COO− salts of Na/K and Cl− salts of Ca(II)/Mg(II)) (50−250 mM).

2.5.4.6. Sequential Separation of Zinc(II), Cadmium(II), and Mercury(II) from Synthetic and Real Samples. Zinc(II), cadmium(II), and mercury(II), analytical congeners of common occurrence,60 sought selective separation from each other for a wider range of application. With this analytical perspective, diverse synthetic mixtures (binary and multicomponent) were prepared. From these synthetic analytical mixtures, mercury(II), zinc(II), and cadmium(II) were sequentially sorbed at their selective extraction pH (viz., mercury(II) at pH 2.5, zinc(II) at pH 4.0, and cadmium(II) at 6.5). After extraction, zinc(II), cadmium(II), and mercury(II) were, respectively, stripped with minimum volume (4 mL) of 5 × 103 μM HNO3, 5 × 103 μM HCl, and 5 × 103 μM H2SO4. The sequential order of elution was found to be cadmium(II)−

mercury(II)−zinc(II). For a broad spectrum of analytical applications, these metal ions were also separated from some real matrices (viz., pond water, tap water, and human blood samples). 5 mL (40 × 103 μM) of each metal ion (viz., zinc(II), cadmium(II), and mercury(II)) was taken in pond/tap water (30 mL) samples or in 10 mL blood samples containing 5 mL conc. HNO3. After digestion, the analytes were filtered (Whatman 40) and finally the volumes were adjusted at 40 mL. The blood samples were centrifuged (1500 rpm) for 20 min before filtration.

3. RESULTS AND DISCUSSION 3.1. Physicochemical Character. SEM images show that the particles are assembled in a cluster and are a little irregular 2353



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Figure 3. (a) Sorption of M(II) (%) vs contact time; (b) pH of analyte vs extraction (%); (c) pH of analyte vs conductance; (d−f) plot of influent sample volume vs recovery (%), respectively, for zinc(II), cadmium(II), and mercury(II).

addition of mercury(II) (Figure 2b). This clearly indicates a 1:1 ion pair formation by tetrameric mercury(II) species with HOMO of the fluorophore and thereby restricts the transition of HOMO electron. Luminescence intensity of both the fluorophore and mercury(II)-nano-FSG-EBT complex remains unchanged in the presence of common contaminants (like Na(I)/K(I) salts of chloride, fluoride, bromide, nitrate, sulfate, phosphate, acetate, and Ca(II)/Mg(II) salts of chloride) in their natural contaminant concentrations (50−250 mM). This clearly suggests the effectiveness of the method for fluorescent detection of mercury(II) at micromolar concentration (0.04 × 10−5 M). 3.2.2. Sample Cleanup of Zinc(II), Cadmium(II), and Mercury(II). The results of the sorption−time relationship comprising numerous data points indicate an initial increase in sorption with contact time but approaches threshold level within 10−16 min (Figure 3a). On the other hand, the plot of log(qe − qt) vs t (minutes) gives a linear relationship (see Supporting Information Figure S5a−c) with good correlation coefficient (y = −0.0597x + (−1.4112); R = 0.9922; SD = 0.09 for zinc(II); y = −0.06x + (−1.4857); R = 0.9953; SD = 0.07 for cadmium(II); and y = −0.0816x + (−1.7544); R = 0.9880; SD = 0.12 for mercury(II)). It generates the first-order rate constant (k1 in min−1) and t1/2 (half-life period in minutes) as 13.75 × 10−2 and 5.04 for zinc(II); 13.82 × 10−2 and 5.0 for cadmium(II); 18.65 × 10 −2 and 3.7 for mercury(II). Consequently, the sorption of metal ions approaches the limiting value at 10−16 min. So, 16 ± 2 min was chosen as the optimum time variable for the further experimental steps. At this equilibrium time (16 ± 2 min) zinc(II), cadmium(II), and mercury(II) were found to be quantitatively extracted respectively at solution pH 4.0−5.0, 6.0−6.5, and 2.0−2.5 (Figure 3b). At these pH ranges they remain as polynuclear

in size (Figure 1a). TEM and SAED photographs of the corresponding nanocompound (20 ± 5 nm) are also shown in Figure 1b,c. Spherical particles are homogeneously distributed within the matrix. The encircled particle produces amorphous scatter of diffuse rings in its selected area electron diffraction (SAED) pattern. BET surface area was found to be excellently high (SABET: 331 m2 g−1) and the material was porous (pore size > 50A) in nature. In our earlier report33,34 the material is well characterized. In its 3-D-structure the molecule contains 4 equiv EBT moieties, placed at four hands of the tetrahedra (Figure 1d,e). Molecular weight was deduced as 7.563 × 103 g. 1 So, it contains 7.563 × 103 × 106 μM g−1, i.e., 132 μM g−1 HOMO/LUMO and at the same time it also contains 132 × 4 μM g−1 of ligands (EBT) for possible metal trapping centers (Figure 1f).33,34 3.2. Analytical Performances of the Extractor. Two kinds of fascinating properties, (i) selectivity in luminescent character and (ii) selectivity in metal extracting abilities, reflect the versatility of the synthesized ion-exchange-material. 3.2.1. Systematic Studies on Florescence Detection of Mercury(II). The nano-FSG-EBT (fluorophore) in DMSO in the concentration range 0.0625 × 10−7 to 0.01 × 10−5 M, upon excitation at 330 nm, shows strong fluorescence at 415.63 nm, with an intensity of 100−575 units (Figure 2a). 0.01 × 10−5 M nanomaterial of highest fluorescent intensity (575 units) was used as a control (Figure 2a). On addition of mercury(II) the solvent polarity parameters were changed, and the emission peak of the uncomplexed fluorophore was slightly shifted (red shift) (solvent relaxation)61 (Figure 2b) and its intensity was found to be reduced by 50% at 1:2 molar ratio for ligand:mercury(II). The luminescence was completely quenched when 1:4 molar ratio of nano-FSG-EBT and mercury(II) is reached and found to be unchanged on further 2354



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f

volume or eluent volume.

a

4.0−5.0 6.0−6.5 2.0−2.5 Zinc(II) Cadmium(II) Mercury(II)

0.1 M HNO3 0.005 M HCl 0.005 M H2SO4

V

200 ± 20 mMb 180 ± 25 mMb 175 ± 15 mMb ≥4 ± 0.5 ≥4 ± 0.5 ≥4 ± 0.5 600 460 540

Studied range. bForeign ion stress for quantitative recovery (≥96%). cInfluent sample volume for quantitative recovery (≥96%). dPF = [Vi × recovery(%)], Vi = influent sample volume and Vf = final

recovery amid foreign ionsa (50−250 mM) optimized flow ratea (1.0−6.5 mL min‑1) BTC μM g‑1 eluentsa (Vf : 4 mL) (Conc. 0.001−0.2 M) optimized sorption pHa (1.5−7.0) metal ions (40 μM mL‑1)

Table 1. Analytical Parameters of Metal Ions with Respect to FSG-EBT

PFd (Vi: 50−1200 mL)a M(II): 1 mL

species [Zn5(OH)6(H2O)2]4+, [Cd4(OH)4(H2O)3]4+, and [Hg4(OH)3(H2O)2]5+ of high molecular mass62,63; this is well supported by their low conductance values (Figure 3c). At the optimum sorption conditions [flow rate ≥ 4 ± 0.5; time = 10− 15 min; pH 4.0−5.0 for zinc(II), 6.0−6.5 for cadmium(II), and pH 2.0−2.5 for mercury(II) (i.e., at which recovery (%) was quantitative (≤96%))] the influent sample volumes (Vi = 800 mL for zinc(II), 600 mL for both cadmium(II) and mercury(II)) for the relevant metal ions were found to be excellently high (Figure 3d−f). On the other hand, systematic studies on elution of cadmium(II), mercury(II), and zinc(II) with different eluents reveal that 4 mL of 5 × 103 μM HCl, 5 × 103 μM H2SO4, and 5 × 103 μM HNO3 solution were found to be enough (recovery ≥96%) to retrieve them sequentially (Table 1 and Table 2). At this minimum eluent volume (Veluent = Vf = 4 mL), maximum Vi and quantitative recovery (%) (obtained from influent sample volume vs recovery (%) relationship (Figure 3d−f)) PF for zinc(II), cadmium(II), and mercury(II) were calculated (eq 4) and the values maximize at 197, 148, and 145 for the respective metal ions (Table 1). At constant final volume, Vf (i.e., volume of eluent = 4 mL; see Table 2) PF is a function of both influent sample volume (Vi) and Recovery (%) of the analyte (eq 4). These two variables have an inverse relationship (Figure 3d−f), forcing PF to be attained at the maximum values mentioned. The retention of the metal ions remained quantitative (recovery ≤ 96%) in the presence of some common electrolytes (viz., Na(I)/K(I) salts of chloride, fluoride, bromide, nitrate, sulfate, phosphate, acetate, and Ca(II)/Mg(II) salts of chloride) up to the stress of 200 ± 20 mM for zinc(II), 180 ± 25 mM for cadmium(II), and 175 ± 15 mM for mercury(II) (Table 1). Such stress belongs to the natural range of contamination. Systematic studies reveal that leakage from the sorbent column started after respectively passing 15 mL zinc(II), 11.5 mL cadmium(II), and 13.5 mL mercury(II) at solution concentration of 40 mM. Eventually the extractant shows very high column sorption capacity (BTC): 600, 460, and 540 μM g−1 for the respective metal ions, zinc(II), cadmium(II), and mercury(II) (Figure 4). The Langmuir maximum sorption capacity, Q0 (714, 591, and 564 μM g−1, respectively, for zinc(II), cadmium(II), and mercury(II)) (plot of Ce/qe vs Ce;(Figure 5a−c) agrees well with these column BTC values. It is also noted that the plot of log Ce vs log qe (Figure 5d−f) was found to be far away from linearity (poor correlation coefficient, R) for the respective metal ions, denying the possibility of multilayer sorption (Freundlich). Now, our objective is to determine which metal ion species are extracted in reality and where do they get adsorbed; how many extraction sites are available per gram of extractor; and finally, a quantitative relationship has to be determined to rationalize the BTC of the extractor. 3.2.3. Identification of the Extracted Species. At quantitative sorption pH, zinc(II), cadmium(II), and mercury(II) are, respectively, present as [Zn5(OH)6(H2O)2]4+, [Cd4(OH)4(H2O)3]4+, and [Hg4(OH)3(H2O)2]5+ along with other possible aqua species.62,63 Now, in order to judge the presence and participation of these polymeric metal ion species in the extraction process, TGA investigations were taken into account. At the range of temperature 40−900 °C, pure exchanger exhibits a higher weight loss (19.34%) than the exchanger containing metal ions (zinc(II) 7.52%, cadmium(II) 8.04%, mercury(II) 15.99%) (Figure 6a−d). At 900 °C, SiO2 would be the end product for the pure exchanger (eq 5), but the residue of metal containing exchanger (at 900 °C) will

197 (800)c 148(600)c 145 (600)c

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contain metal oxides along with SiO2 (eq 6). As a result of this, at 40−900 °C, the TGA weight loss differences between the pure and the metal-containing exchanger (11.82%, 11.3%, and 3.35%, respectively, for zinc(II), cadmium(II), and mercury(II); obtained by subtracting the TGA weight loss for curves b−d from curve a (Figure 6)) would be the measure of weight loss for the conversion of metal ion species ([Zn5(OH)6(H2O)2]4+, [Cd4(OH)4(H2O)3]4+, and [Hg4(OH)3(H2O)2]5+, extracted on the extractor) to their corresponding oxides (eq 6); computed as 12.47%, 10.14%, and 2.60%, respectively, for zinc(II), cadmium(II), and mercury(II) (eq 7). The close proximity between the words (computed values: 12.47%, 10.14%, and 2.60%) and deeds (experimental TGA differences: 11.82%, 11.3%, and 3.35%) has thus unquestionably justified [Zn 5 (OH) 6 (H 2 O) 2 ] 4 + , [ Cd 4 ( O H ) 4 (H 2 O) 3 ] 4 + , a nd [Hg4(OH)3(H2O)2]5+ as the sorbed species. TGA weight loss (10.45%) of the pure extractor at 100 °C suggests the presence of surface water (denoted as δ = 49; eq 5) and it was found to be much higher than that for the metal loaded extractor (2.57 ± 0.14%) (Figure 6b−d). This reveals that the metal-loaded extractor contains only 25% of the original surface water (i.e., δ1 = 49−37 ± 2; eq 6). It suggests that during the sorption process, a considerable amount of surface water was replaced from the extractor surface.

Table 2. Stripping Behavior of Metal Ions with Acids of Different Concentrations volume (mL) and concentration (μM) of acids for quantitative elution different acids HNO3 HClO4 H2SO4 HCl CH3COOH

zinc(II) 4 mL; 5 × 103 μM

cadmium(II)

6 mL; 5 × 103 μM 3 5 mL; 5 × 10 μM 5 mL; 5 × 103 μM 6 mL; 4 mL; 10 × 103 μM 5 × 103 μM 15 mL; 4 mL; 10 × 103 μM 5 × 103 μM 10 mL; 15 mL; 10 × 103 μM 5 × 103 μM

mercury(II) 5 mL; 5 × 103 μM 5 mL; 10 × 103 μM 4 mL; 5 × 103 μM 15 mL; 10 × 103 μM 10 mL; 10 × 103 μM

[Si(OSi)3 (OH) ·0.1H 2O]n = 28 Figure 4. Breakthrough curve of zinc(II), cadmium(II), and mercury(II).

[−Si(CH3)2 NHC6H4NNEBT]4 ·δ H 2O → {SiO2 } + CO2 + NOx + H 2O + SOx

(5)

Figure 5. Isotherm profiles for zinc(II), cadmium(II), and mercury(II): (a−c) Langmuir; (d−f) Freundlich. 2356



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Figure 6. TGA weight loss (a) pure extractor. (b) Mercury-loaded extractor [Hg4(OH)3(H2O)2 → 4HgO + H2O + 5H; Wt loss = 2.60% (exp: 19.34−15.99 = 3.35%)]. (c) Cadmium-loaded extractor [Cd4(OH)4(H2O)3 → 4CdO + 3H2O + 2H2; Wt loss = 10.14% (exp: 19.34−8.04 = 11.3%)]. (d) Zinc-loaded extractor [Zn5(OH)6 (H2O)2 → 5ZnO + 3H2O + 2H2; Wt loss = 12.47% (exp: 19.34−7.52 = 11.82%)].

cadmium(II), and mercury(II)); 657, 526, and 552 μM g−1. The experimental findings of isotherms are in conformity with the Langmuir monolayer sorption and agree with the ion-pair formation with an appreciable binding affinity (0.16, 0.1, and 0.07 L μM−1, the respective Langmuir “b” values for zinc(II), cadmium(II), and mercury(II) are found to be quite high). FTIR spectra for metal-loaded extractor (FSG-EBT-M(II); M = zinc(II), cadmium(II), or mercury(II)) differs from the pure extractor by the following: (i) appearance of two more developed peaks at 2354−2363 cm−1 (high intense sharp peak for C−N linkage33,34,64) and 1871−2002 cm−1 (broad and low intense peak for diazo-NN33,34,64); (ii) appearance of two new peaks at 1230 ± 12 cm−1 and 555 ± 5 cm−1; (iii) more diffuse character (3400 ± 400 cm−1) of the broad peak appears at 3300 ± 300 cm−1 (for -NH and H-bonded surface water33,34,64); and (iv) disappearance of the intense broad peak found at 1346 cm−1 in its FT-IR spectra (Figure 7a). FTIR peak intensity is a function of change in dipole moment and concentration of the particular bond.64 Symmetry of the pure extractor is lost by virtue of HOMO: metal ion species 1:1 ion pair formation (Figure 1f) at one hand of the tetrahedra and the change in dipole moment gets increased. It increases the peak intensity of the corresponding peaks (within HOMO region) at 2354−2363 cm−1 and 1871−2002 cm−1. The coordinated water molecules and MOH bending modes in bridging OH groups in aqua hydroxyl metal complexes ([Zn 5 (OH) 6 (H 2 O) 2 ] 4 + , [Cd 4 (OH) 4 (H 2 O) 3 ] 4 + , and

[Si(OSi)3 (OH) ·0.1H 2O]n = 28 [−Si(CH3)2 NHC6H4NNEBT]4 ·δ1H 2O· [M θ(μ2 ‐OH)φ (H 2O)r ](2p − φ) + → {SiO2 + MO2 }+CO2 + NOx + H 2O + SOx

(6)

where θ = 4 for mercury(II) and cadmium(II), 5 for zinc(II); φ = 3 for mercury(II), 4 for cadmium(II), 5 for zinc(II); r = 2 for zinc(II) and 3 for cadmium(II); p = charge of metal ion; δ = 49 and δ1 = 49−37 ± 2 ⎡ [W ⎤ [Mθ (μ2 ‐OH)ϕ (H2O)r ](2p − ϕ) + − W[MO] × θ ] Wt loss(%) = ⎢ × 100⎥ ⎢⎣ ⎥⎦ (W[Mθ(μ2 ‐OH)ϕ (H2O)r ](2p − ϕ) +) (7)

3.2.4. Mechanistic Path of the Sorption Process. The ionexchange material contains 132 μM g−1 electron-rich HOMO (section 3.1) which are able to produce 1:1 ion pairs (section 3.2.1) with the metal ion species ([Zn5(OH)6(H2O)2]4+, [Cd4(OH)4(H2O)3]4+, and [Hg4(OH)3(H2O)2]5+). It attains the breakthrough capacity (BTC) at 132 × 5 μM g−1 for zinc(II) and 132 × 4 μM g−1 for both cadmium(II) and mercury(II). These calculated BTC values (660 and 528 μM g−1) are in close proximity to the average of experimental values (BTCcolumn: 600, 460, and 540 μM g−1 and BTCbatch:714, 591, and 564 μM g−1for the respective metal ions, zinc(II), 2357



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Figure 7. (a) FT-IR spectra of FSG-EBT and FSG-EBT-M(II) (M(II): zinc(II), cadmium(II), and mercury(II)). (b) Plot of metal sorption capacity (100% = 600, 460, and 540 μMg1− for zinc(II), cadmium(II), and mercury(II)) vs concentration of mineral acids. (c) Plot of mercury(II) sorption capacity (100% =540 μM g−1) vs reusability (cycles).

Table 3. Binary and Multicomponent Separation of Diverse Metal Ions from Their Synthetic Solutiona amount of cations (μM) sample no.

cations

added

recovered

recovery (%)

relative error (%)

1

Cadmium(II) Zinc(II) Mercury(II) Zinc(II) Cadmium(II) Mercury(II) Zinc(II) Cadmium(II) Mercury(II)

200 200 200 200 200 200 200 200 200

192.8 194.2 194.4 193.6 196.2 192.4 193.6 194.4 193.8

96.4 97.2 97.2 96.8 98.1 96.2 96.8 97.2 96.9

3.6 2.9 2.8 3.2 1.9 3.8 3.2 2.8 3.1

2 3 4

eluents used (μM) 5 5 5 5 5 5 5 5 5

× × × × × × × × ×

103 103 103 103 103 103 103 103 103

HCl HNO3 H2SO4 HNO3 HCl HCl HNO3 HCl H2SO4

Sample volume: 400 mL; pH 2.5, 4.0, and 6.5; Concentration: 500 μM; Flow rate: 5 mL min−1; Eluents volume: 4 mL; Temperature: 27 °C; Amount of FSG-EBT: 3 g; Column height: 3 cm].

a

[Hg4(OH)3(H2O)2]5+) are confirmed by the appearance of the two new peaks at 555 ± 5 cm−1 and 1230 ± 12 cm−1 (Figure 7a), respectively, in the FT-IR spectra of metal-loaded complexes.64 It is also to be noted that the original FT-IR peak (at 3300 ± 300 cm−1) for H-bonded surface water was found to be broadened (3400 ± 400 cm−1), thus exemplifying the presence of H-bonded residual surface water (found in TGA; δ1 = 49−37 ± 2; eq 6), found at the vicinity of HOMO:metal ion species ion pair 1:1 complex. All these results in unison clearly and quantitatively describe BTC as a function of the amount of HOMO (eq 8) which is confirmed by luminescence quenching (section 3.2.1), 1:1 ion pair formation of tetrameric-mercury(II) species with HOMO of the probe

BTC = {amount of HOMO} × x

(8)

where x = 4 for both cadmium(II) and mercury(II), and x = 5 for zinc(II). 3.2.5. Desorption Constants. A plot (Figure 3d−f) of Vi (influent volume) vs recovery (%) of analyte in question generates two linear segments for each (y = −0.024x + 100, R = 0.999, SD = 0.067, and y = −0.150x + 220, R = −1.0, SD = 0.01 for zinc(II); y = −0.0051x + 100.41, R = −0.999; SD = 0.049, and y = −0.115x + 165, R = −1.0, SD = 0.01 for cadmium(II); y = −0.0028x + 100, R = −0.998, SD = 0.01, and y = −0.12x +171, R = 1.0, SD = 0.036 for mercury(II), respectively) intersecting at a volume of 800 mL for cadmium(II)), the degree of desorption gets increased; and the recovery (%) would be zero for the sample volume ≥1467 mL, 1435, and 1425 mL (extrapolated value), respectively, for zinc(II), cadmium(II), and mercury(II). This reveals that cationic parts of the solute and solvent take part in sorption and desorption by interchanging their positions during column operation. Thus, desorption efficiency of analyte becomes predominant for higher sample size (mL) of the mobile phase and it completes for a solvent volume greater than 1470 mL. That is, at this optimum condition, the mobile phase itself acts as the stripping agent. 3.2.6. Sequential Separation of Zinc(II), Cadmium(II), and Mercury(II). To explore the versatility in analytical application of the developed method, several synthetic mixtures (binary and multicomponent) (400 mL) containing different metal ions were prepared. The separation of these metal ions was achieved either by selective extraction (which is effected by exploiting the differences in pH) or by selective stripping (employing suitable eluents (Table 3)). The extracted metal ions were selectively stripped with the help of a selective stripping agent of minimum volume to obtain the targets at their concentration-enriched state. In most cases, recoveries (%) were quantitative (97.2 ± 0.9%) and the relative errors were found to be 96%) (Table 4). 3.2.7. Chemical Stability and Reusability. The ion-exchange material was kept in mineral acids for 4 h at different concentrations and its sorption capacity toward mercury(II) was investigated to find out the chemical stability and utility of the material. The mercury(II) sorption capacity (100% = 540 μM g−1) was found to be quantitative (≤95%) up to 8 M HNO3, 8 M HCl, and 5 M H2SO4 (Figure 7b). Extended operation at higher level of pH yields hydrolysis of the substrate and it leads to cleavage of the bonded phase, subsequently reducing sorption capacity. Because of significant hydrolysis, the bonded phase “bleeds” to yield a pinkish effluent. The

4. CONCLUSION In summary, the mesoporous extractor contains 132 μM g−1 spatially well separated HOMO. Nanomaterial is selectively able to detect mercury(II) at trace level (LOD ≥ 0.04 × 10−5 M) amid its chemical congeners (zinc(II), cadmium(II)) and other possible cationic/anionic interference of raw water. At a particular time interval, HOMO makes a 1:1 complex with a particular metal ion species. Zinc(II), cadmium(II), and mercury(II) being respectively present as μ2O-hydroxo [Zn 5 (OH) 6 (H 2 O) 2 ] 4 + , [ Cd 4 ( O H ) 4 (H 2 O) 3 ] 4 + , a nd [Hg4(OH)3(H2O)2]5+gets quantitatively extracted, respectively, at pH 4.0−5.0, 6.0−6.5, and 2.0−2.5. BTC for zinc(II), cadmium(II), and mercury(II) were found to be high (respectively, 600, 460, and 540 μM g−1). Experimental BTC values are in close proximity to the calculated values (i.e., HOMO values (132 μM g−1) × x, where x = 4 for both cadmium(II) and mercury(II), and 5 for zinc(II)). Preconcentration factors (197, 148, and 145, respectively, for zinc(II), cadmium(II), and mercury(II)) were optimized at a sample volume of 800 mL for zinc(II), and 600 mL for both cadmium(II) and mercury(II). Sequential separations of these metallic toxicants of analytical utility from their synthetic and real mixtures were achieved quantitatively (recovery >95%).

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jced.7b00224. Instrumentation, reagents and chemicals, preparation of the extractor (FSG-EBT), 3-D structural optimization of the synthesized extractor, adsorption kinetics (PDF)

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AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected] ; dr. [email protected]. Tel.: +91-9474738517. 2359



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(14) Yao, C.-H.; Jiang, S.-J.; Sahayam, A. C.; Huang, Y.-L. Speciation of Mercury in Fish Oils Using Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry. Microchem. J. 2017, 133, 556− 560. (15) Houserová, P.; Kubáň , P.; Kubáň , V. Ion Exchange Preconcentration and Separation of Mercury Species by CE with Indirect Contactless Conductometric Detection. Electrophoresis 2006, 27, 4508−4515. (16) Atia, A. A.; Donia, A. M.; Elwakeel, K. Z. Selective Separation of Mercury(II) Using a Synthetic Resin Containing Amine and Mercaptan as Chelating Groups. React. Funct. Polym. 2005, 65, 267− 275. (17) Ding, S.-Y.; Dong, M.; Wang, Ya-W.; Chen, Y.-T.; Wang, H.-Z.; Su, C.-Y.; Wang, W. Thioether-Based Fluorescent Covalent Organic Framework for Selective Detection and Facile Removal of Mercury(II). J. Am. Chem. Soc. 2016, 138, 3031−3037. (18) Hosseini, M. S.; Hashemi-Moghaddam, H. Sensitized Extraction Spectrophotometric Determination of Mercury(II) with Dithizone after Its Flotation as Ion-Associate Using Iodide and Ferroin. Talanta 2005, 67, 555−559. (19) Chai, X.; Chang, X.; Hu, Z.; He, Q.; Tu, Z.; Li, Z. Solid Phase Extraction of Trace Mercury(II) on Silica Gel Modified with 2-(2Oxoethyl)Hydrazine Carbothioamide and Determination by ICP-AES. Talanta 2010, 82, 1791−1796. (20) Faraji, M.; Yamini, Y.; Saleh, A.; Rezaee, M.; Ghambarian, M.; Hassani, R. A Nanoparticle-Based Solid-Phase Extraction Procedure Followed by Flow Injection Inductively Coupled Plasma-Optical Emission Spectrometry to Determine Some Heavy Metal Ions in Water Samples. Anal. Chim. Acta 2010, 659, 172−177. (21) Lee, J. S.; Gomez-Salazar, S.; Tavlarides, L. L. Synthesis of Thiol Functionalized Organo-Ceramic Adsorbent by Sol-Gel Technology. React. Funct. Polym. 2001, 49, 159−172. (22) Tsoi, Y. K.; Tam, S.; Leung, K. S. Y. Rapid Speciation of Methylated and Ethylated Mercury in Urine Using Headspace Solid Phase Microextraction Coupled to LC-ICP-MS. J. Anal. At. Spectrom. 2010, 25, 1758−1762. ̌ (23) Spicka, J.; Svoboda, L.; Janoǔskov́a, D. Determination of Methylmercury in Fish Muscle by HPLC Method with UV Detection. Chem. Listy 2003, 97, 1024−1026. (24) Blanco, R. M.; Villanueva, M. T.; Uŕıa, J. E. S.; Sanz-Medel, A. Field Sampling, Preconcentration and Determination of Mercury Species in River Waters. Anal. Chim. Acta 2000, 419, 137−144. (25) Mena, M. L.; McLeod, C. W.; Jones, P.; Withers, A.; Minganti, V.; Capelli, R.; Quevauviller, P. Microcolumn Preconcentration and Gas Chromatography-Microwave Induced Plasma-Atomic Emission Spectrometry (GC-MIP-AES) for Mercury Speciation in Waters. Fresenius' J. Anal. Chem. 1995, 351, 456−460. (26) Haji-Shabani, A. M.; Dadfarnia, S.; Nasirizadeh, N. Speciation Analysis of Mercury in Water Samples by Cold Vapor Atomic Absorption Spectrometry after Preconcentration with Dithizone Immobilized on Microcrystalline Naphthalene. Anal. Bioanal. Chem. 2004, 378, 1388−1391. (27) Mandal, B.; Ghosh, N. Combined Cation-Exchange and Extraction Chromatographic Method of Pre-concentration and Concomitant Separation of Bismuth(III) with High Molecular Mass Liquid Cation Exchanger. J. Hazard. Mater. 2010, 182, 363−370. (28) Mandal, B.; Ghosh, N. Extraction Chromatographic Method of Preconcentration and Separation of Lead (II) with High Molecular Mass Liquid Cation Exchanger. Desalination 2010, 250, 506−514. (29) Mandal, B.; Roy, U. S.; Datta, D. N.; Ghosh, N. Combined Cation-Exchange and Extraction Chromatographic Method of Preconcentration and Concomitant Separation of Cu(II) with High Molecular Mass Liquid Cation Exchanger after Its Online Detection. J. Chromatogr. A 2011, 1218, 5644−5652. (30) Mandal, B.; Barman, M. K.; Srivastava, B. Extraction Chromatographic Method of Preconcentration, Estimation and Concomitant Separation of Vanadium (IV) with Silica Gel-Versatic 10 Composite. J. Chromatogr. Sci. 2014, 52, 1135−1144.

Bhabatosh Mandal: 0000-0002-5474-6778 Funding

This research was supported by UGC (ref. no. 3274/NETJUNE2011); (Grant 201213-NETJRF-10076−8-ACTIVE), New Delhi and the Department of Chemistry, Visva Bharati University, India. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS B. Srivastava thankfully acknowledges the experimental support from CSIR-CMERI-Laboratory, India. REFERENCES

(1) Zhang, W.; Zhen, G.; Chen, L.; Wang, H.; Li, Y.; Ye, X.; Tong, Y.; Zhu, Y.; Wang, X. Economic Evaluation of Health Benefits of Mercury Emission Controls for China and The Neighboring Countries in East Asia. Energy Policy 2017, 106, 579−587. (2) Kim, N.-S.; Ahn, J.; Lee, B.-K.; Park, J.; Kim, Y. Environmental Exposures to Lead, Mercury, and Cadmium Among South Korean Teenagers (KNHANES 2010−2013): Body Burden and Risk Factors. Environ. Res. 2017, 156, 468−476. (3) Antochshuk, V.; Jaroniec, M. 1-Allyl-3-Propylthiourea Modified Mesoporous Silica for Mercury Removal. Chem. Commun. 2002, 3, 258−259. (4) Gao, Y.; Shi, Z.; Long, Z.; Wu, P.; Zheng, C.; Hou, X. Determination And Speciation Of Mercury in Environmental and Biological Samples by Analytical Atomic Spectrometry. Microchem. J. 2012, 103, 1−14. (5) Li, X.; Zhang, Y.; Chang, Y.; Xue, B.; Kong, X.; Chen, W. Catalysis-Reduction Strategy for Sensing Inorganic and Organic Mercury Based on Gold Nanoparticles. Biosens. Bioelectron. 2017, 92, 328−334. (6) Houserov́a, P.; Matejıcek, D.; Kuban, V. High-Performance Liquid Chromatographic/Ion-Trap Mass Spectrometric Speciation of Aquatic Mercury as its Pyrrolidinedithiocarbamate Complexes. Anal. Chim. Acta 2007, 596, 242−250. (7) Celebi, M. S.; Ozyoruk, H.; Yıldız, A.; Abacı, S. Determination of Hg2+ on Poly(Vinylferrocenium) (PVF+)-Modified Platinum Electrode. Talanta 2009, 78, 405−409. (8) Sun, P.; Zhang, B.; Zeng, X.; Luo, G.; Li, X.; Yao, H.; Zheng, C. Deep Study on Effects of Activated Carbon’s Oxygen Functional Groups for Elemental Mercury Adsorption Using Temperature Programmed Desorption Method. Fuel 2017, 200, 100−106. (9) Zhang, Y.; Zhang, Z.; Liu, Z.; Norris, P.; Pan, W.-p. Study on the Mercury Captured by Mechanochemical and Bromide Surface Modification of Coal Fly Ash. Fuel 2017, 200, 427−434. (10) Oh, Y.; Morris, C. D.; Kanatzidis, M. G. Polysulfide Chalcogels with Ion-Exchange Properties and Highly Efficient Mercury Vapor Sorption. J. Am. Chem. Soc. 2012, 134, 14604−14608. (11) Yamini, Y.; Rezaee, M.; Khanchi, A.; Faraji, M.; Saleh, A. Dispersive Liquid−Liquid Microextraction Based on the Solidification of Floating Organic Drop Followed by Inductively Coupled PlasmaOptical Emission Spectrometry as a Fast Technique for the Simultaneous Determination of Heavy Metals. J. Chromatogr. A 2010, 1217, 2358−2364. (12) Martinis, E. M.; Berton, P.; Olsina, R. A.; Altamirano, J. C.; Wuilloud, R. G. Trace Mercury Determination in Drinking and Natural Water Samples by Room Temperature Ionic Liquid BasedPreconcentration and Flow Injection-Cold Vapor Atomic Absorption Spectrometry. J. Hazard. Mater. 2009, 167, 475−481. (13) Döker, S.; Bosgelmez, I.̇ I.̇ Rapid Extraction and Reverse PhaseLiquid Chromatographic Separation of Mercury(II) and Methylmercury in Fish Samples with Inductively Coupled Plasma Mass Spectrometric Detection Applying Oxygen Addition into Plasma. Food Chem. 2015, 184, 147−153. 2360



Article

(31) Barman, M. K.; Srivastava, B.; Chatterjee, M.; Mandal, B. Solidphase extraction, Separation and Preconcentration of Titanium (IV) with SSG-V10 from Some Other Toxic Cations: A Molecular Interpretation Supported by DFT. RSC Adv. 2014, 4, 33923−33934. (32) Goswami, A.; Singh, A. K. Enrichment of Iron(III), Cobalt(II), Nickel(II), and Copper(II) by Solid-Phase Extraction with 1,8Dihydroxyanthraquinone Anchored to Silica Gel Before Their Determination by Flame Atomic Absorption Spectrometry. Anal. Bioanal. Chem. 2002, 374, 554−560. (33) Srivastava, B.; Barman, M. K.; Chatterjee, M.; Mandal, B. EBT Anchored SiO2 3-D Microarray: A Simultaneous Entrapper of Two Different Metal Centers at High and Low Oxidation States Using its Respective Highest Occupied and Lowest Unoccupied Molecular Orbital. RSC Adv. 2015, 5, 55686−55703 and references therein.. (34) Srivastava, B.; Barman, M. K.; Chatterjee, M.; Roy, D.; Mandal, B. Solid Phase Extraction, Separation and Preconcentration of Rare Elements Thorium(IV), Uranium(VI), Zirconium(IV), Cerium(IV) and Chromium(III) amid Several Other Foreign Ions with Eriochrome black T Anchored to 3-D Networking Silica Gel. J. Chromatogr. A 2016, 1451, 1−14. (35) Chatterjee, M.; Srivastava, B.; Barman, M. K.; Mandal, B. Combined Cation-Exchange and Solid Phase Extraction for the Selective Separation and Preconcentration of Zinc, Copper, Cadmium, Mercury and Cobalt among Others Using Azo-Dye Functionalized Resin. J. Chromatogr. A 2016, 1440, 1−14. (36) Weetall, H. H.; Hersh, L. S. Urease Covalently Coupled to Porous Glass. Biochim. Biophys. Acta Enzymol. 1969, 185, 464−465. (37) Weetall, H. H. Trypsin and Papain Covalently Coupled to Porous Glass: Preparation and Characterization. Science 1969, 166, 615−616. (38) Weetall, H. H. Alkaline Phosphatase Insolubilized by Covalent Linkage to Porous Glass. Nature 1969, 223, 959−960. (39) Weetall, H. H. Storage Stability of Water-Insoluble Enzymes Covalently Coupled to Organic and Inorganic Carriers. Biochim. Biophys. Acta 1970, 212, 1−7. (40) Hill, J. M. Silica Gel as an Insoluble Carrier for the Preparation of Selective Chromatographic Adsorbents: The Preparation of 8Hydroxyquinonline Substituted Silica Gel for the Chelation Chromatography of Some Trace Metals. J. Chromatogr. 1973, 76, 455−458. (41) Sugawara, K. F.; Weetall, H. H.; Schucker, G. D. Preparation, Properties, and Applications of 8-Hydroxyquinoline Immobilized Chelate. Anal. Chem. 1974, 46, 489−492. (42) Tong, A.; Akama, Y.; Tanaka, S. Pre-Concentration of Copper, Cobalt and Nickel with 3-methyl-1-phenyl-4-stearoyl-5-pyrazolone Loaded on Silica Gel. Analyst 1990, 115, 947−949. (43) Kasahara, I.; Terashima, M.; Mukaiyama, T.; Taguchi, S. Synthesis of Silica-Gel Immobilized Xanthurenic Acid and Its Application to the Preconcentration/Determination of Trace Metals in Natural Water Samples. Bunseki Kagaku 1998, 47, 1061−1067. (44) Mahmoud, M. E.; Osman, M. M.; Amer, M. E. Selective PreConcentration and Solid Phase Extraction of Mercury(II) from Natural Water by Silica Gel-Loaded Dithizone Phases. Anal. Chim. Acta 2000, 415, 33−40. (45) Soliman, E. M.; Mahmoud, M. E.; Ahmed, S. A. Synthesis, Characterization and Structure Effects on Selectivity Properties of Silica Gel Covalently Bonded Diethylenetriamine Mono- and BisSalicyaldehyde and Naphthaldehyde Schiff,s Bases Towards Some Heavy Metal Ions. Talanta 2001, 54, 243−253. (46) Marshall, M. A.; Mottola, H. A. Synthesis of Silica-Immobilized 8-Quinolinol with (Aminophenyl)trimethoxysilane. Anal. Chem. 1983, 55, 2089−2093. (47) Liu, P.; Pu, Q.; Su, Z. Synthesis of Silica Gel Immobilized Thiourea and Its Application to the On-Line Preconcentration and Separation of Silver, Gold and Palladium. Analyst 2000, 125, 147−150. (48) Kocjan, R. Retention of Some Metal Ions and Their Separation on Silica Gel Modified with Acid Red 88. Microchim. Acta 1999, 131, 153−158.

(49) Polyakov, A. I.; Rogovin, Z. A. Synthesis of New Cellulose DerivativesXXIII. Synthesis of Chlorocellulose and Its Conversion Products. Preparation of Amino- and Nitrilocellulose. Polym. Sci. U.S.S.R. 1963, 4, 610−618. (50) Tashiro, T.; Shimura, Y. Removal of Mercuric Ions by Systems Based on Cellulose Derivatives. J. Appl. Polym. Sci. 1982, 27, 747−756. (51) Barman, M. K.; Chatterjee, M.; Srivastava, B.; Mandal, B. Characterization and Density Functional Theory Optimization of a Simultaneous Binder (FSG-XO) of Two Different Species Exploiting HOMO−LUMO Levels: Photoelectronic and Analytical Applications. J. Chem. Eng. Data 2015, 60, 2197−2208. (52) Chatterjee, M.; Srivastava, B.; Barman, M. K.; Mandal, B. Facile Synthesis of a Luminescent Material, PAN@{SiO2}n, Having a Simultaneous Binding Capacity of High and Low Oxidation States: (HOMO/or LUMO), Quantum-mechanical Descriptor of Breakthrough Capacity. Anal. Sci. 2016, 32, 989−998. (53) Wen, S.; Zeng, T.; Liu, L.; Zhao, K.; Zhao, Y.; Liu, X.; Wu, H. C. Highly Sensitive and Selective DNA-Based Detection of Mercury(II) with α-Hemolysin Nanopore. J. Am. Chem. Soc. 2011, 133, 18312− 18317. (54) Bera, K.; Das, A. K.; Nag, M.; Basak, S. Development of a Rhodamine−Rhodanine-Based Fluorescent Mercury Sensor and Its Use to Monitor Real-Time Uptake and Distribution of Inorganic Mercury in Live Zebrafish Larvae. Anal. Chem. 2014, 86, 2740−2746. (55) Xiong, E.; Wu, L.; Zhou, J.; Yu, P.; Zhang, X.; Chen, J. A Ratiometric Electrochemical Biosensor for Sensitive Detection of Hg2+ based on Thymine−Hg2+−thymine Structure. Anal. Chim. Acta 2015, 853, 242−248. (56) Wu, J.; Liu, W.; Ge, J.; Zhang, H.; Wang, P. New Sensing Mechanisms for Design of Fluorescent Chemosensors Emerging in Recent Years. Chem. Soc. Rev. 2011, 40, 3483−3495. (57) Ghosh, P.; Saha, S. K.; Roychowdhury, A.; Banerjee, P. Recognition of an Explosive and Mutagenic Water Pollutant, 2,4,6Trinitrophenol, by Cost-Effective Luminescent MOFs. Eur. J. Inorg. Chem. 2015, 2015, 2851−2857. (58) Mahata, P.; Mondal, S. K.; Singha, D. K.; Majee, P. Luminescent Rare-earth-based MOFs as Optical Sensor. Dalton trans. 2017, 46, 301−328. (59) Pribil, R. Chelometry, Basic Determinations; Praha, Czechoslovakia, Chemapol, Prague, 1961. (60) Cotton, F. A.; Wilkinson, G.; Murillo, C. A.; Bochmann, M. Advanced Inorganic Chemistry, 5th ed.; John Wiley & Sons: New York, 1998. (61) Reichardt, C. Empirical Parameters of Solvent Polarity as Linear ″Free Enthalpy″ Relationships. Angew. Chem. 1979, 91, 119−131. (62) Schindler, P.; Reinert, M.; Gamsjager, H. On the Thermodynamics of Metal Carbonates 3. Solubility Constants and Free Formation Enthalies of ZnCO3 and Zn5(OH)6(CO3)2 at 25°C. Helv. Chim. Acta 1969, 52, 2327−2337. (63) Baes, C. F.; Mesmer, R. E. The Hydrolysis of Cations; Wiley & Sons: Inc., New York, 1976. (64) Nakamoto, K. Infrared and Raman Spectra of Inorganic and Coordination Compounds, Part B; John Wiley & Sons: New York, 1977.

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