Preconcentration and Determination of Trace Hg(II) Using a Cellulose Nanofiber Mat Functionalized with MoS2 Nanosheets

Recent Progress in Triazole Based Chromogenic and Fluorogenic Chemosensor for the Detection of Hg2+ Metal ion: A Review

Triazole, a heterocyclic organic molecule containing nitrogen, exhibits strong coordination abilities with various metal ions. Several synthetic techniques, including Claisen-Schmidt condensation, Huisgen-1,3-dipolar cycloaddition reaction (CuAAC), Pellizzari synthesis, Einhorn-Brunner synthesis, Dimroth rearrangement and Boulton-Katritzky Rearrangement have been employed to synthesize triazole derivatives. Experimental and spectroscopic investigations have demonstrated that triazole possesses a high binding affinity for heavy metal ions such as Pb2+, Hg2+, Cd2+, Cu2+ and Al3+. The increasing environmental pollution caused by the uncontrolled discharge of heavy metal ions into water bodies and open spaces poses a serious threat to ecosystem and public health. To address this issue, a cost-effective and efficient chemosensor based on triazole has been developed for selective detection of toxic heavy metal ions. Notably, triazole exhibits fluorescence quenching or enhancement upon interaction with the Hg2+ ions, attributed to changes in its absorption and emission spectra upon coordination. This unique photophysical behaviour makes triazole-based probes valuable tools for monitoring Hg2+ ions in environmental and biological samples. This review provides a comprehensive overview of triazole-based fluorescent chemosensors for Hg2+ ions detection, covering advancements made between 2010-2025. The study highlights the high specificity, excellent sensitivity, and low detection limits of these sensors, emphasizing their potential for practical applications in environmental monitoring and analytical chemistry.

Porous organic polymers for selective enrichment of trace Cu(ii) in food and water samples

Porous organic polymers (POPs) were synthesized by polymerization of benzene triamine and trimesoyl chloride. The POP material is water-stable and shows selective extraction of Cu(ii) due to its intrinsic nitrogen-rich surface, which forms a chelate with Cu(ii) ions. The prepared polymeric material was characterized through Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, energy-dispersive X-ray elemental mapping, and scanning electron microscopy for surface group analysis and structural morphology studies. A microcolumn was developed using POPs for the preconcentration of trace Cu(ii) from complex real samples. The proposed method shows a high enrichment factor of 900 and a quantification limit of 1.1 ppb for Cu(ii) ions. The accuracy of the developed method was confirmed by analyzing standard reference materials (NIES 8 and NIES 10c) and the standard addition method. The method shows good precision with an RSD value of less than 5%.

A Review on Pyridine Based Colorimetric and Fluorometric Chemosensor for Detection of Hg2+ ion

Pyridine, N-containing heterocyclic organic compound, displays strong coordination capabilities with various metal ions. It can be synthesized through various methods, such as Friedlander synthesis, heterocumulene synthesis, cross-coupling reactions, the Radziszewski reaction, Bonnemann cyclization, as well as cobalt-catalyzed synthesis. Experimental and spectroscopic analyses have demonstrated a strong binding affinity between pyridine and several heavy metal ions, including Pb2+, Hg2+, and Cd2+ ions. The escalating environmental pollution caused by the disposal of heavy metal ions in rivers, open air, and water reservoirs poses a significant threat to both ecosystem and human health. To address these environmental challenges, a cost-effective and easily synthesized chemosensor has been prepared for identifying toxic heavy metal ions in various samples. Pyridine's photophysical properties make it an effective sensor for detecting Hg2+ ions, displaying fluorescence quenching or enhancement in their presence. The coordination between pyridine and Hg2+ ions lead to shifts in the absorption spectra. The pyridine-based sensor has been evaluated for its sensitivity, selectivity, and detection limits under different experimental conditions. Pyridine's solubility and environmental stability make it applicable for real-time detection, making pyridine probes valuable tool for monitoring toxic Hg2+ ions in the environment. The results demonstrate that the pyridine-based chemosensor exhibits good selectivity and sensitivity for targeting Hg2+ ions, with detection limits within acceptable ranges. This review (from years 2011 to 2023) emphasizes the preparation of various substituted pyridine compounds as selective, sensitive, and specific sensors for real-time detection of Hg2+ ions.

Functionalized porous carbon microspheres packed column for solid phase extraction and preconcentration of trace metal ions in food and water samples

Porous materials play a crucial role in the extraction of trace analytes; yet, the attainment of high selectivity and efficient regeneration continues to pose a considerable problem. In this study, we employed a green method to synthesize porous carbon microspheres. These microspheres were subsequently functionalized with aminophosphonic acid to facilitate the extraction of heavy metal ions from real samples. A comprehensive analysis of the aminomethylphosphorylated carbon microspheres was conducted using FTIR, SEM, EDX, TEM, BET and water contact angle measuring techniques. The potential optimization of analyte enrichment can be accomplished by the proposed solid-phase extraction (SPE) approach, which notably reduces spectrum interferences following sample purification. Following the IUPAC equation, the detection limit of the proposed method was found to be 0.04 ng mL-1, after running 20 replicate blank tests. The primary focus of sequestration of trace metal ions is the formation of metal-ligand chelates within the carbon spheres, resulting in enhanced selectivity and extraction rates exceeding 99.9% from samples with low concentrations. The present studies show a significant preconcentration limit of 0.4 ng mL-1 and a substantial preconcentration factor of 500. The method was implemented to examine real food and water samples, and the obtained data exhibit significant accuracy with a relative standard deviation (RSD) of less than 5%.

Valorization of sugarcane bagasse with in situ grown MoS2 for continuous pollutant remediation and microbial decontamination

In this study, sugarcane bagasse (SB) was strategically subjected to a delignification process followed by the in situ growth of multi-layered molybdenum disulfide (MoS2) nanosheets with hexagonal phase (2H-phase) crystal structure via hydrothermal treatment. The MoS2 nanosheets underwent self-assembly to form nanoflower-like structures in the aligned cellulose inter-channels of delignified sugarcane bagasse (DSB), the mechanism of which was understood through FTIR and XPS spectroscopic studies. DSB, due to its porous morphology and abundant hydroxyl groups, shows remediation capabilities of methylene blue (MB) dye through physio-sorption but shows a low adsorption capacity of 80.21 mg/g. To improve the removal capacity, DSB after in situ growth of MoS2 (DSB-MoS2) shows enhanced dye degradation to 114.3 mg/g (in the dark) which further improved to 158.74 mg/g during photodegradation, due to catalytically active MoS2. Interestingly, DSB-MoS2 was capable of continuous dye degradation with recyclability for three cycles, reaching an efficiency of > 83%, along with a strong antibacterial response against Gram-positive Staphylococcus aureus (S.aureus) and Gram-negative Escherichia coli (E. coli). The present study introduces a unique strategy for the up-conversion of agricultural biomass into value-added bio-adsorbents, which can effectively and economically address the remediation of dyes with simultaneous microbial decontamination from polluted wastewater streams.

In Situ Fabrication and Characterization of g-C3N4 onto Cellulose Nanofibers and Selective Separation of Heavy Metal Ions

Graphitic carbon nitride nanosheets were synthesized onto cellulose nanofiber surfaces utilizing an eco-friendly salt melt approach. The fabricated material CNF@C3N4 selectively removes Ni(II) and Cu(II) from electroplating wastewater samples. The immobilization of g-C3N4 on solid substrates eases handling of nanomaterial in a flow-through approach and mitigates sorbent loss during column operations. Characterization techniques such as scanning electron microscopy, tunneling electron microscopy, and X-ray photoelectron microscopy were employed to analyze the surface morphology and chemical bonding within the synthesized material. Selective Cu(II) and Ni(II) sorption predominantly arises from the soft-soft interaction between metal ions and associated nitrogen groups. An inner-sphere surface complexation mechanism effectively elucidated the interaction dynamics between the metal and CNF@C3N4. Experimental findings demonstrated satisfactory separation of Ni(II) and Cu(II) ions, with the extraction of 340.0 and 385.0 mg g-1 of material, respectively. Additionally, the devised technique was executed for the preconcentration and quantification of trace metals ions in water samples with a detection limit and limit of quantification of 0.06 and 0.20 μg L-1, respectively.

Use of transition metal dichalcogenides (TMDs) in analytical sample preparation applications

Since the discovery of graphene, nano-sized two-dimensional (2D) transition metal dichalcogenides (TMDs) such as MoS2, MoSe2, MoTe2, NbS2, NbSe2, WS2, WSe2, TaS2 and TaSe2, which have been classified as next-generation nanomaterials resembling graphene (G) have complementary basic properties with those of graphene in terms of their practical applications. TMDs are attracting great attention due to their attractive physical, chemical and electronic properties. Despite being overshadowed by graphene in terms of frequency of use, TMDs have been used frequently in many areas in recent years instead of carbon-based materials such as graphene (G), graphene oxide (GO), carbon nanotubes (CNTs) and nanodiamonds (NDs). It is seen that the first and frequent uses of TMDs, which are classified as new generation materials, are in the fields of catalysis, electronic applications, hydrogen production processes and energy storage, but it has been used as an adsorbent in sample preparation techniques in recent years. Similar to graphene, layers of TMDs are held together by weak van der Waals interactions. The sandwiched layers of TMDs provide sufficient and effective interlayer spaces so that foreign molecules, ions and atoms can easily enter these spaces between the layers. Intermolecular interactions increase with the entry of different materials into these spaces, and thus, high activity, adsorption capacity and efficiency are obtained in adsorption-based analytical sample preparation methods. Although there are about 35 research articles using TMDs, which are classified as promising materials in analytical sample preparation techniques, no review studies have been found. This review, which was designed with this awareness, contains important informations on the properties of metal dichalcogenides, their production methods and their use in analytical sample preparation techniques.

Hybrid biomaterials to preconcentrate and determine toxic metals and metalloids: a review

Toxic elements represent a serious threat to the environment and cause harmful effects on different environmental components, even at trace levels. These toxic elements are often difficult to detect through the typical instrumentation of an analytical laboratory because they are found at very low concentrations in matrices such as food and water. Therefore, preconcentration plays a fundamental role since it allows the effects of the matrix to be minimized, thus reaching lower detection limits and greater sensitivity of detection techniques. In recent years, solid-phase extraction has been successfully used for the preconcentration of metals as an environmentally friendly technique due to the fact that it eliminates or minimizes the use of reagents and solvents and offers reduced analysis times and low generation of waste in the laboratory. Hybrid biomaterials are low-cost, eco-friendly, and useful as efficient solid phases for the preconcentration of elements. In this review, recent investigations based on the use of hybrid biomaterials for the preconcentration and determination of toxic metals are presented and discussed, given special attention to bionanomaterials. A brief description of hybrid biomaterials often used for analytical purposes, as well as analytical techniques mostly used to characterize the hybrid biomaterials, is explained. Finally, the future prospects that encourage the search for new hybrid biomaterials are commented upon.

Covalently Functionalized Cellulose Nanoparticles for Simultaneous Enrichment of Pb(II), Cd(II) and Cu(II) Ions

Cellulose nanoparticles are sustainable natural polymers with excellent application in environmental remediation technology. In this work, we synthesized cellulose nanoparticles and covalently functionalized them with a multi-functional group possessing ligands. The hybrid material shows excellent adsorption properties for the simultaneous extraction of multiple metal ions in the sample preparation technique. The sorbent shows excellent sorption capacity in the range of 1.8-2.2 mmol/g of material. The developed method was successfully employed for the simultaneous extraction of Pb(II), Cd(II) and Cu(II) from real-world samples (industrial effluent, river water, tap and groundwater) and subsequently determined by inductively coupled plasma optical emission spectroscopy (ICP-OES). The method shows a preconcentration limit of 0.7 ppb attributes to analyze the trace concentration of studied metal ions. The detection limit obtained for Pb(II), Cd(II) and Cu(II) is found to be 0.4 ppb.

Graphene Oxide Deposited with Transition Metal Chalcogenide for Selective Extraction and Determination of Hg(II): Experimental and Computational Analysis

A graphene oxide (GO/CdS) nanocomposite was synthesized by an in situ hydrothermal process and studied to develop a micro solid phase extraction procedure. Microscopic and spectroscopic characterizations have confirmed the successful preparation of the GO/CdS composite. The prepared nanocomposite selectively extracts Hg(II) ions from various water samples (tap, river, and groundwater). The intriguing characteristic of GO sheets is to provide exceptional hydrophilicity and Hg(II) accessibility to surface-decorated CdS nanoparticles. The GO/CdS nanocomposite shows excellent extraction of trace Hg(II) in a short interval of time. Computations based on density functional theory (DFT) suggest that energetically favorable multinuclear S-Hg binding leads to rapid adsorption with high sorption capacity at GO/CdS sites. The analytical features of merit suggested that the developed method has a low detection limit (0.07 µg L^-1) and shows good accuracy and precision (with RSD 3.5%; N = 5). The developed method was verified by analyzing SRM 1641d (Standard Reference Material) and real samples after spiking to a predetermined amount.

Covalently linked mercaptoacetic acid on ZrO2 coupled cellulose nanofibers for solid phase extraction of Hg(ii): experimental and DFT studies

Zirconium oxide (ZrO₂) nanoparticles were introduced onto cellulose nanofibers after being covalently functionalized with mercaptoacetic acid. We experimentally demonstrate that the nanocomposite is capable of selectively capturing Hg(ii) from aqueous samples down to trace level concentrations. Density functional theory (DFT) calculations indicate that energetically favorable R-S → Hg ← O-R bidentate complex formation enhances the rapid adsorption, leading to selective extraction of Hg(ii). Furthermore, the loss of ZrO₂ particles during flow-through studies is controlled and restricted after binding to CNF rather than being used directly in the column. The Hg(ii) selectivity is primarily due to the Lewis soft-soft acid-base chelation of Hg(ii) with the mercapto functionalities of the adsorbent. The experimental observations depict a high sorption capacity of 280.5 mg g^-1 for Hg(ii). The limit of detection and quantification of the proposed approach were found to be 0.04 μg L^-1 and 0.15 μg L^-1, respectively. Analytical method accuracy and validity were determined by analyzing Standard Reference Materials and by the standard addition method (recovery > 95% with a 5% RSD). The findings of a Student's t-test were found to be lower than the critical Student's t value. Real water samples were successfully analyzed using the developed procedure.

Boosting photocatalytic efficiency of MoS2/CdS by modulating morphology

CdS-based composites as the highly efficient photocatalyst have been extensively investigated in recent years due to the suitable band gap and high photocatalytic efficiency. In this study, the effect of various factors (pH, U(VI) concentration, contents, and types of photocatalyst) on photocatalytic reduction of U(VI) by MoS₂/CdS composite was investigated. The optimized experimental conditions (e.g., pH 7.0, 20 mg/g U(VI), and 1.0 g/L photocatalyst) was obtained by batch techniques. Approximately 97.5% of U(VI) was photo-catalytically reduced into U(IV) by 2.5 wt% MoS₂/CdS composite within 15 min. After 5 cycles, 2.5 wt% MoS₂/CdS composite still exhibited the high removal efficiency of U(VI) under 50-min irradiation, indicating the good stability. The photo-reduction mechanism of U(VI) on MoS₂/CdS composite was attributed to the O^-₂ radicals by quenching experiments, ESR, and XPS analysis. The findings indicate that CdS-based catalyst has a great potential for the photocatalytic reduction of uranyl in actual environmental remediation.

Facile synthesis of hierarchical MoS2/ZnS @ porous hollow carbon nanofibers for a stable Li metal anode

Lithium metal is considered as an ideal anode candidate for next generation Li battery systems since its high capacity, low density, and low working potential. However, the uncontrollable growth of Li dendrites and infinite volume expansion impede the commercialized applications of Li-metal anodes. In this work, we rationally designed and constructed a hierarchical porous hollow carbon nanofiber decorated with diverse metal sulfides (MS-ZS@PHC). This composite scaffold has three advantages: First, the synergistic effect of multiple-size lithiophilic phases (nano ZnS and micro MoS₂) can regulate Li ions nuclei and grow up homogenously on the scaffold. Second, the enlarged interplanar spacing of MoS₂ microsphere on the fibers can provide abundant channels for Li ions transportation. Third, the porous scaffold can confine the volume expansion of Li metal anode during cycling. Therefore, in a symmetrical cell, the MS-ZS@PHC host presents a homogenous Li plating/stripping behavior and runs steadily for 1100 h at 5 mA cm^-2 with a capacity of 5 mAh cm^-2 and even for 700 h at 10 mA cm^-2 with a capacity of 1 mAh cm^-2. A full cell using MS-ZS@PHC /Li composite as anode and coupled with LiFePO₄ as cathode delivers an excellent cyclic and rate performances.

Cationic microcrystalline cellulose - Montmorillonite composite aerogel for preconcentration of inorganic anions from dairy wastewater

Development of efficient adsorbents to inorganic anions as a solid phase extraction (SPE) material is highly desirable for chromatographic analysis and pollution control. In this work we developed a new hybrid cationic microcrystalline cellulose aerogel composite. Cationic cetylpyridinium imbedded montmorillonite (CPC-MT) was uniformly entrapped in microcrystalline cellulose (MCC) to enhance anionic adsorption efficiency and mechanical stability. The developed CPC-MT@MCC aerogel was used as an SPE adsorbent for anions from dairy wastewater by coupling with ion-column chromatography. Further quaternized CPC-MT@MCC aerogel (CPC-MT@QMCC) showed unique low density (10.6 mg cm^-3), large specific surface area (320 m² g^-1), porosity 70%, 800 mg g^-1 nitrate adsorption capacity within 60 min and ease of elution in alkaline solutions. The CPC-MT@QMCC aerogel showed efficient regeneration and reuse performances for up to 10 cycles. More importantly, a dynamic binding efficiency of 710 mg g^-1 highlights its excellent performance for practical applications. 96% of nitrate anion from environmental manure wastewater samples were adsorbed with 98.7% recovery. A good linear relationship was obtained in the range of 0.01-10 mg L^-1 and the limits of detection was 0.5 mg L^-1 using CPC-MT@QMCC aerogel as a preconcentration column. The successful synthesis of such intriguing and economic CPC-MT@QMCC aerogel may provide a promising matrix for high-performance and high efficiency chromatographic media.

Direct Synthesis of Sulfur-Decorating PAMAM Dendrimer/Mesoporous Silica for Enhanced Hg(II) and Cd(II) Adsorption

Water security caused by heavy metals poses a deleterious hazard to public health and the ecological system. The construction of adsorbents by polyamidoamine (PAMAM) dendrimers for efficient removal of metal ions has attracted considerable interest. However, the general method for the fabrication of these adsorbents was achieved by the surface chemical modification of the substrates with PAMAM dendrimer, which usually causes the defects of low density and uneven distribution of the dendrimer, the blocking of pores, and reducing the adsorption performance. Hence, the development of a new method for preparation of PAMAM dendrimer-based adsorbent to realize the efficient and enhanced adsorption of metal ions is still a challenge. Herein, methylisothiocyanate decorated PAMAM dendrimer/mesoporous silica composites (G0-S-1/x, G1.0-S-1/x, G2.0-S-1/x, x = 2, 4, 6, 8, 10) were synthesized by the direct sol-gel reaction of alkoxysilyl-containing functional PAMAM dendrimer. The adsorbents display enhanced adsorption property for Hg(II) and Cd(II) as compared with the same adsorbents which were prepared by traditional chemical modification method. Take G2.0-S-1/2 as an example, the maximum adsorption capacities are 2.41 and 0.87 mmol·g^-1 for Hg(II) and Cd(II), respectively . Moreover, the adsorbents show excellent selective adsorption and regeneration property. G2.0-S-1/2 displays distinct selectivity for Hg(II) with the presence of Co(II), Pb(II), Cd(II), and Cu(II). The regeneration percentage still maintains 95.2% after five adsorption-desorption cycles. The adsorption mechanism is also certified by the experimental method and theoretical calculation.

Preconcentration and determination of trace Hg(ii) using ultrasound-assisted dispersive solid phase microextraction

Defect rich molybdenum disulfide (MoS₂) nanosheets were hydrothermally synthesized and their potential for ultrasound assisted dispersive solid phase microextraction of trace Hg(ii) ions was assessed. Ultrasonic dispersion allows the MoS₂ nanosheets to chelate rapidly and evenly with Hg(ii) ions and results in improving the precision and minimizing the extraction time. The multiple defect rich surface was characterized by X-ray diffraction and high-resolution transmission electron microscopy. The surface charge of intrinsically sulfur rich MoS₂ nanosheets and their elemental composition was characterized by zeta potential measurements, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. The cracks and holes on the basal planes of MoS₂ led to diffusion of the Hg(ii) ions into the interior channels. Inner-sphere chelation along with outer-sphere electrostatic interaction were the proposed mechanism for the Hg(ii) adsorption onto the MoS₂ surface. The experimental data showed good selectivity of MoS₂ nanosheets towards Hg(ii) adsorption. The systematic and constant errors of the proposed method were ruled out by the analysis of the Standard Reference Material (>95% recovery with <5% RSD). The Student's t-test values for the analyzed Standard Reference Material were found to be less than the critical Student's t value at 95% confidence level. The limit of detection (3S) was found to be 0.01 ng mL⁻¹. The MoS₂ nanosheets were successfully employed for the analysis of Hg(ii) in environmental water samples.

Hg(ii) ion adsorption onto an MoS₂ surface.

Graphene oxide lamellar membrane with enlarged inter-layer spacing for fast preconcentration and determination of trace metal ions

We report a graphene oxide (GO) lamellar membrane with increased inter-layer spacing for efficient permeation of water molecules and heavy metal ions through nanoporous graphene oxide. The inter-layer spacing of the GO sheets in the lamellar structure was increased by introducing poly-aminophosphonic acid (APA) in between the GO sheets. We demonstrate experimentally, the use of a prepared membrane (GO–APA) by a SPE technique for the preconcentration and extraction of heavy metal ions by chelate formation and their determination by ICP-OES. We found that this sub-micrometer-thick membrane allows unimpeded permeation of water molecules through two-dimensional capillaries formed across the pores and by closely spaced graphene sheets. Compared to the bulk GO sorbent, GO–APA membrane offers enhanced sensitivity and permeability for heavy metal ions due to relatively large inter-layer spacing and high surface area (extraction phase) with a high number of active functional groups. The potential of this technique for the preconcentration and extraction of Pb(ii), Cd(ii) and Cu(ii) is illustrated with the contaminated ground water and industrial waste water analysis. The detection limit achieved for studied ions was 1.1 ng L⁻¹, under optimized experimental conditions. The co-existing ions did not hinders the extraction of trace heavy metal ions. Accuracy of the developed method was assessed by analyzing Standard Reference Materials. The Student's t test values were found to less than the critical Student's t value of 4.303 at the 95% confidence level. The method shows good precision as coefficients of variation for five replicate measurements were found to be 4–5%.

A porous graphene oxide membrane with increased interlayer spacing of GO sheets was prepared by covalently introducing poly-aminophosphonic acid in between the GO sheets. The membrane was successfully employed for the extraction of heavy metal ions.

Facile synthesis of magnetic molybdenum disulfide@graphene nanocomposite with amphiphilic properties and its application in solid-phase extraction for a wide polarity of insecticides in wolfberry samples

A novel magnetic molybdenum disulfide@graphene (Fe₃O₄/MoS₂@G) nanocomposite with amphiphilic properties was prepared via a co-mixing solvothermal method. To demonstrate the feasibility of Fe₃O₄/MoS₂@G as a sorbent during sample preparation, it was employed for the magnetic solid phase extraction (MSPE) of ten pyrethroids, three triazoles and two acaricide pyridaben and picoxystrobin in an emulsified aqueous solution. Dichloromethane was used as the extractant to form an emulsified aqueous solution. Subsequently, the Fe₃O₄/MoS₂@G sorbent with amphiphilic properties was used to retrieve 15 wide polarity insecticides from dichloromethane via MSPE. The proposed method has the advantage of being applicable to different polar pesticides, strengthening the capacity of enrichment and purification of target analytes. The π-π interaction between the hydrophilic and hydrophobic moieties of Fe₃O₄/MoS₂@G and the aromatic rings of target analytes were responsible for the efficient sorption. Thus, a reliable, convenient, and efficient method for the analysis of 15 insecticides with wide polarity in wolfberry samples was established by coupling Fe₃O₄/MoS₂@G nanocomposite MSPE with gas chromatography-mass spectrometry (GC-MS) analysis. The obtained linearity of this method was in the range from 1 to 5000 ng mL^-1 for 15 analytes, with determination coefficients (R²) ≥0.9907. The limit of detection (LOD) for 15 insecticides was in the range from 0.1 to 5.0 ng g^-1. The recoveries of 15 insecticides from spiked wolfberry samples were in the range from 71.41% to 110.53%, and RSD was less than 14.8%.

3D Nanoarchitecture of Polyaniline-MoS2 Hybrid Material for Hg(II) Adsorption Properties

We report the facile hydrothermal synthesis of polyaniline (PANI)-modified molybdenum disulfide (MoS2) nanosheets to fabricate a novel organic-inorganic hybrid material. The prepared 3D nanomaterial was characterized by field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction studies. The results indicate the successful synthesis of PANI-MoS2 hybrid material. The PANI-MoS2 was used to study the extraction and preconcentration of trace mercury ions. The experimental conditions were optimized systematically, and the data shows a good Hg(II) adsorption capacity of 240.0 mg g-1 of material. The adsorption of Hg(II) on PANI-MoS2 hybrid material may be attributed to the selective complexation between the-S ion of PANI-MoS2 with Hg(II). The proposed method shows a high preconcentration limit of 0.31 µg L-1 with a preconcentration factor of 640. The lowest trace Hg(II) concentration, which was quantitatively analyzed by the proposed method, was 0.03 µg L-1. The standard reference material was analyzed to determine the concentration of Hg(II) to validate the proposed methodology. Good agreement between the certified and observed values indicates the applicability of the developed method for Hg(II) analysis in real samples. The study suggests that the PANI-MoS2 hybrid material can be used for trace Hg(II) analyses for environmental water monitoring.

Semiconducting Polymer Interfaces for Electrochemically Assisted Mercury Remediation

Nanostructured polymer interfaces can play a key role in addressing urgent challenges in water purification and advanced separations. Conventional technologies for mercury remediation often necessitate large energetic inputs, produce significant secondary waste, or when electrochemical, lead to strong irreversibility. Here, we propose the reversible, electrochemical capture and release of mercury, by modulating interfacial mercury deposition through a sulfur-containing, semiconducting redox polymer. Electrodeposition/stripping of mercury was carried out with a nanostructured poly(3-hexylthiophene-2,5-diyl)-carbon nanotube composite electrode, coated on titanium (P3HT-CNT/Ti). During electrochemical release, mercury was reversibly stripped in a non-acid electrolyte with 12-fold higher release kinetics compared to nonfunctionalized electrodes. In situ optical microscopy confirmed the rapid, reversible nature of the electrodeposition/stripping process with P3HT-CNT/Ti, indicating the key role of redox processes in mediating the mercury phase transition. The polymer-functionalized system exhibited high mercury removal efficiencies (>97%) in real wastewater matrices while bringing the final mercury concentrations down to <2 μg L^-1. Moreover, an energy consumption analysis highlighted a 3-fold increase in efficiency with P3HT-CNT/Ti compared to titanium. Our study demonstrates the effectiveness of semiconducting redox polymers for reversible mercury deposition and points to future applications in mediating electrochemical stripping for various environmental applications.