Mercury In Aqueous Solutions Research Articles

Dansyl-labelled cellulose as dual-functional adsorbents for elimination and detection of mercury in aqueous solution via aggregation-induced emission

Dansyl chloride fluorophore exhibits typical aggregation induced fluorescence emission behavior in acetone/water solution. To realize the integration of detective and adsorptive functions, dansyl chloride is covalently immobilized on cellulose substrate to fabricate an efficient adsorbent for mercury ions in water. The as-prepared material exhibits excellent fluorescence sensing performance exclusively for Hg (II) with the presence of other metal ions. A sensitive and selective fluorescence quenching across the concentration range of 0.1–8.0 mg/L is observed with a detection limit of 8.33 × 10−9 M as a result of the inhibition of aggregation induced emission caused by the coordination between adsorbent and Hg (II). Besides, the adsorption properties for Hg (II) including the influence of initial concentration and contact time are investigated. Langmuir model and pseudo-second-order kinetics are demonstrated to fit well with the adsorption experiment for the uptake of Hg (II) by the functionalized adsorbent, also, intraparticle diffusion kinetic model is proved to aptly describe the Hg (II) removal in aqueous solution. In addition, the recognition mechanism is considered to originate from the Hg (II) triggered structural reversals of naphthalene ring units which are verified by the X-ray photoelectron spectroscopy and density functional theory calculation. Moreover, the synthesis method used in this work also provides a strategy for the sensing application of organic sensor molecules with AIE properties in which the aggregated behavior could be appropriately realized.

Removal of Mercury in Aqueous Solutions Using Tri n-Butyl Phosphate-Based Polymer Inclusion Membrane

Polymer inclusion membranes (PIM) have gained global attention in the removal of heavy metals from aqueous samples. Mercury is a toxic metal that can cause serious health effects to humans even if present in traces. Hence, its removal from water bodies and wastewaters is a necessary action. The present work, thus, aims at studying the removal of Hg2+ ions by using PIM with a new and unexplored neutral carrier, namely, Tri n-butyl phosphate and Dioctyl phthalate as a plasticizer. One hundred percent removal was attained for feed phase mercury concentrations from 0.01 to 2 mg/L and about 96% for 10 mg/L under optimum conditions (thickness of the membrane: 30 μm, feed phase acid: 0.3 M, strip phase alkali: 0.4 M, carrier: 3% and stirring speed: 400 rpm). The PIM system has been successfully demonstrated to remove trace concentrations of mercury in spiked seawater, thermal powerplant wastewater discharge, and contaminated lake water samples. The PIM was highly stable (60 h) and selective for Hg2+ ions. Also, the most significant factor in the transport of mercury through the PIM was determined as the feed phase mercury concentration using the Taguchi method. Thus, the proposed PIM system could be used for the selective removal of mercury ions from water and wastewater samples.

Incorporation of perovskite nanocrystals into lanthanide metal-organic frameworks with enhanced stability for ratiometric and visual sensing of mercury in aqueous solution

In-situ growth of CsPbBr3 nanocrystal into Eu-BTC was realized for synthesis of dual-emission CsPbBr3@Eu-BTC by a facile solvothermal method, and a novel ratiometric fluorescence sensor based on the CsPbBr3@Eu-BTC was prepared for rapid, sensitive and visual detection of Hg2+ in aqueous solution. The transmission electron microscopy (TEM), X-ray diffraction pattern (XRD), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller (BET) analysis were used to verify the successful incorporation of CsPbBr3 into the Eu-BTC. Meanwhile, the CsPbBr3@Eu-BTC nanocomposite maintained high fluorescence performance and stability in aqueous solution. After adding Hg2+, the green fluorescence of CsPbBr3 was quenched and the red fluorescence of Eu3+ remained unchanged, while the color changed from green to red obviously. The occurrence of dynamic quenching and electron transfer were verified by fluorescence lifetime, Stern-Volmer quenching constant and XPS analysis. The ratiometric fluorescence sensor shows high analytical performance for Hg2+ detection with a wide linear range of 0–1 μM and a low detection limit of 0.116 nM. In addition, it also shows high selectivity for the detection of Hg2+ and can be successfully applied to detect Hg2+ in environmental water samples. More importantly, a novel paper-based sensor based on the CsPbBr3@Eu-BTC ratiometric probe was successfully manufactured for the visual detection of Hg2+ by naked eyes. This new type of ratiometric fluorescent sensor shows great potential for applications in point-of-care diagnostics.

Pre-grafting effect on improving adsorption efficiency of cellulose based biosorbent for Hg (II) removal from aqueous solution

Pre-grafting technique with excellent biocompatibility is introduced to cellulose based adsorbent material which greatly enhances the adsorption properties like adsorption capacity, equilibrium time and regeneration performance. • Pre-grafting technique greatly enhances the adsorption performance of adsorbent. • Adsorption capacity is retained more than 85% after five cycles of regeneration. • Pre-grafting technique based on cellulose has excellent biocompatibility. Adsorption technique is considered to be an effective way to remove heavy metal species from aqueous solutions and cellulose based materials are widely used as good candidates of adsorbents. However, low grafting efficiency of functional groups has been a major challenge reducing the heavy metal adsorption capacity of cellulose based adsorbents. In this work, a diethylenetriaminepentaacetic acid modified cellulose is synthesized by an efficient catalyzed approach on the basis of glycidyl methacrylate pre-grafting (G-DMC). As a contrast, epichlorohydrin is employed as coupling side chain to react with the same polyacid (DMC) to evaluate the effect of pre-grafting. It is verified that “pre-grafting technique” significantly improves the load efficiency of polyacid and enhances the adsorption performance that the as-prepared adsorbent using pre-grafting technique shows much higher adsorption capacity ( Q m ) towards mercury in aqueous solutions with Q m of 443.8 mg/g, which is 3.5 folds of the epichlorohydrin grafted one. In addition, the kinetic adsorption experiments confirm that G-DMC achieves its adsorption equilibrium in a shorter time of 10 min. After five cycles of regeneration process, G-DMC could maintain 88.13% of its original adsorption capacity. Moreover, the live/dead cell fluorescence staining demonstrates the good biological safety of the material that the cell viability of murine L929 fibroblasts could retain close to 100% after 24 h of cultivation with G-DMC. Thus, this pre-grafting strategy is expected to provide an environmentally friendly method to amplify the adsorption capacity of the designed receptor for guest species.

Highly sensitive B, N co-doped carbon dots for fluorescent and colorimetric dual-mode detection of mercury ions in wastewater

Mercury ions (Hg2+) owing to excessive discharge cause serious damage to human health and the water ecosystem via bioaccumulation in food chains. Novel materials employed for the high-performance monitoring of Hg2+ are urgently required. Herein, using sucrose, boric acid, and melamine as raw materials, a new nanomaterial sensor, namely boron and nitrogen co-doped carbon dots (B, N-CDs), was designed for fluorescent and colorimetric dual-mode detection of Hg2+. Because of the occurrence of both dynamic and static quenching, B, N-CDs were utilized to function as fluorescent sensors for detecting Hg2+ with a limit of detection (LOD) of 5.3 nM. B, N-CDs performed an action for catalytic oxidation of 3,3′,5,5′-Tetramethylbenzidine (TMB) to a blue cationic radical via peroxidase mimetic activity. By sequentially adding cysteine and Hg2+ to control the emergence of the TMB cation radical, a sensor for the Hg2+ assay was established through the colorimetric "on-off-on" signal and the LOD was as low as 7.8 nM. Moreover, the application potential of B, N-CDs for complex water environments was demonstrated to be excellent. In summary, the dual-mode detection method delivers some valid strategies for the detection of mercury in aqueous solutions employing the functional nanomaterials mentioned, and opens new avenues in tackling the problem of heavy metal ion pollution for environmental monitoring and remediation.

Functionalization of biosourced silica and surface reactions with mercury in aqueous solutions

This study presents the production of pure silica from rice husk and its stepwise functionalization with triethoxysilane (TES) and silver nanoparticles. The derived TES-SiO2 (0.97 mmol TES per g of SiO2) and Ag0@SiO2 (3.70–21.60 mg Ag per g of SiO2) materials were used for the removal of Hg2+ from aqueous solutions in the presence of chloride ions. The removal of Hg2+ was rapid and the equilibrium solid phase loading was between 21 and 101 mg/g. TES-SiO2 was more effective than Ag0@SiO2 in removing mercury due to the highly reactive hydride groups. In the case of Ag0@SiO2 samples the removal of Hg2+ is proportional to the amount of Ag0. The materials were characterized before and after the removal of Hg2+ to allow insights into the interaction mechanism. The reaction products for TES-SiO2 sample were calomel (Hg2Cl2) and AgCl. On the surface of Ag0@SiO2 samples besides these products the silver amalgams Ag1.1Hg0.9 and possibly Ag2Hg3 were identified. These results show that redox reactions between silicon-hydride group, Ag0 and Hg2+ take place on the surface of the materials. The coexistence of calomel and silver amalgams on amorphous silica is observed for the first time while the calomel formation in heterogeneous Hg2+ redox systems is a rare observation. Also, the samples showed extraordinary efficiency in terms of Hg:Ag molar ratio (2.28–3.02), considerably higher than those reported before. Besides the beneficial effect of the Cl- presence on the removal of Hg2+ from the solution there is evidence of a hyperstoichiometric interaction between Ag0 and Hg2+ at the nanoscale.

Encapsulation of Perovskite Nanocrystals into Lanthanide Metal-Organic Frameworks with Enhanced Stability for Ratiometric and Visual Sensing of Mercury in Aqueous Solution

Encapsulation of Perovskite Nanocrystals into Lanthanide Metal-Organic Frameworks with Enhanced Stability for Ratiometric and Visual Sensing of Mercury in Aqueous Solution

Recycling of Tetra pak wastes via pyrolysis: Characterization of solid products and application of the resulting char in the adsorption of mercury from water

This paper provides a detailed analysis of the recycling of Tetra Pak waste via pyrolysis to recover the most valuable solid products within its composition, char and aluminum, and the subsequent application of the char in the adsorption of mercury in aqueous solutions. The impact of the Tetra Pak pyrolysis conditions on the char and aluminum yields and their associated properties have been analyzed using a variety of physico-chemical techniques. Tetra Pak-derived chars showed outstanding mercury adsorption properties (up to 215.7 mg/g) that can be attributed to the heterogeneous surface chemistry composed mainly by oxygenated functional groups associated to C, Ca, Al and Si. Tetra Pak pyrolysis allowed an effective recovery of aluminum at pyrolysis temperatures of 600 and 800 °C. Higher temperatures, up to 1000 °C, promote its oxidation to aluminum oxide and hydroxide. These findings contribute to increase the versatility in the Tetra Pak reuse to develop new adsorbents with promising performance for water treatment and the associated recovery of aluminum for further industrial applications. • New adsorbents for mercury removal were obtained from Tetra pak pyrolysis. • Tetra pak pyrolysis produced aluminum with different composition of oxide and hydroxyde. • Tetra pak-derived chars are outstanding adsorbents for mercury removal.

Recent Progress in Functional Materials for Selective Detection and Removal of Mercury(II) Ions

AbstractSevere disease and environmental pollution derived from heavy metal ions has become one of the major problems in global public health. In particular, mercury(II) as one type of highly poisonous pollutant can destroy human metabolism, central nervous system, and immune system, representing a critical threat to living systems. Therefore, exploitation of new strategies for designing and synthesizing eco‐friendly, efficient, and economical materials for selective detection and removal of Hg2+ is of great importance. Among the various measures for sensing, detection, and removal of mercury ions, advanced functional systems including nanomaterials, polymers, aggregation‐induced emission luminogens, and porous materials have attracted considerable attention over the past years due to their capabilities of real‐time detection, rapid removal, great anti‐interference, quick response, high selectivity, and low limit of detection. In this review, some efficient techniques and strategies for the detection and removal of mercury in aqueous solutions using the abovementioned functional materials are overviewed and the ways in which these advanced material systems are used to tackle the problem of mercury pollution are also discussed.

Synthesis of biosourced silica–Ag nanocomposites and amalgamation reaction with mercury in aqueous solutions

This paper focuses on the synthesis of a new silver nanocomposite adsorbent derived from rice husk as raw material. The synthesis is based on triethoxysilane chemistry and the reduction of silver without the aid of reductant chemicals. The derived AgNPs@SiO2 nanocomposites are fully characterized and then used for the removal of mercury (II) from aqueous solutions. The results demonstrated that the affinity of the composite for mercury is high and the removal mechanism is adsorption accompanied by a redox reaction between mercury and silver followed by the formation of calomel and amalgams between silver and mercury. The silver-mercury reaction is complex, and its stoichiometry seems to scale with the silver content. Besides the importance of the surface reactions, the successful implementation of biosourced silica for mercury removal from water is useful for the development of strategies for the valorization of agricultural waste and boosts the concept of circular economy and bioeconomy.

Adsorption performance of Bacillus licheniformis sp. bacteria isolated from the soil of the Tigris River on mercury in aqueous solutions

ABSTRACTMercury is known to be one of the most toxic heavy metals in the environment and is released into the water systems in significant quantities through natural events and industrial process activities. Many chemical materials are used as adsorbents in the removal of toxic metals from the environment and wastewaters. However, using microorganisms as bio-sorbents instead of chemical materials has become common recently due to their low cost, easy availability and presence in nature. In this study, Bacillus licheniformis in the soil isolated from the Tigris River was used as bio-sorbent. The mercury (Hg(II)) absorption behaviour of Bacillus licheniformis bacteria (BLB) was investigated using inductively coupled plasma mass spectrometry. The effects of equilibrium of adsorption time, temperature, adsorbent dosage and pH on the adsorption of Hg (II) onto BLB were determined. The maximum adsorption capacity of Hg (II) onto BLB was determined as 82.12 mg/g (T = 25°C, pH 5, Co = 50 mg/L, m = 25 mg). The BLB was characterised using Fourier transform infrared spectroscopy analysis, thermal gravimetric analysis/differential thermal analysis, scanning electron microscopy analysis and energy-dispersive X-ray spectroscopy analysis. In addition, pseudo-first-order and pseudo-second-order kinetic models were applied. The equilibrium data for the adsorption of Hg(II) onto BLB were examined by the Langmuir and Freundlich isotherm models. The activation energy was calculated using the pseudo-second-order rate constant. These results suggested the BLB can be used as an efficient adsorbent for the removal of Hg(II) metal ions from wastewater. When the results of bio-sorption studies were examined, it was found that the bio-sorbent could be reused easily. The present study suggests that microorganism bio-sorbents are useful for the efficient removal of mercury from aqueous solutions.

Acoustic cavitation generates molecular mercury(ii) hydroxide, Hg(OH)2, from biphasic water/mercury mixtures.

Emulsification of elemental mercury in aqueous solution in the form of grey particles occurs upon exposure to intense sound fields. We show the concomitant formation of molecular Hg(OH)2 in the solution phase reaching a saturation limit of 0.24 mM at 25 °C. The formation of Hg(OH)2 is consistent with the 'hot spot' model which suggests the formation of OH˙ as a result of acoustic cavitation; such radicals are proposed to combine with Hg to form the Hg(OH)2 species here characterised using voltammetry.

Microwave assisted synthesis of poly (N-vinylimidazole) grafted chitosan as an effective adsorbent for mercury (II) removal from aqueous solution: Equilibrium, kinetic, thermodynamics and regeneration studies

In the present study, chitosan-N-vinyl imidazole was first synthesized and characterized and then its capacity for removal of mercury (II) ions from water was assessed. The graft copolymerization of N-vinyl imidazole onto chitosan chains has been developed in aqueous medium using microwave irradiation. The obtained copolymer was characterized by Fourier Transform Infrared (ATR-FTIR), solid-state 13C Nuclear Magnetic Resonance (NMR), Differential Scanning Calorimetric (DSC) and Thermogravimetric Analysis (TGA). Mercury (II) ions removal capacity by the chitosan-N-vinyl imidazole were investigated in aqueous solutions using different amounts of these ions at pH = 6.0. The effect of the contact time, kinetics and thermodynamic studies on the adsorption of mercury ions was also reported. The maximum adsorption capacity was found to be 112.35 mg g−1 from the Langmuir isotherm model at 25 °C. The obtained negative value of (kJ mol−1) and (kJ mol−1) indicated the spontaneous and endothermic nature of the reactions. The regeneration of CS-N-vinyl imidazole was investigated using PEG-400 in water as desorbing agent. This data make chitosan-N-vinyl imidazole a potential material adsorbent for mercury (II) removal.HighlightsSynthesize of CS-N-vinyl imidazole is done under microwave irradiation.Removal of mercury in aqueous solution was performed in batch studies.Mercury adsorption has been simulated using Langmuir and Freundlich models.Thermodynamic properties of the adsorption process have been determined.Regeneration has been studied using PEG-400 as desorbing agent.

A Turn off-on Fluorescent Chemosensor for Sequential Determination of Mercury and Biothiols.

The selective and sensitive determination of biothiols in aqueous media has been great attention due to their important role in biological and pharmacological processes. We synthesized tryptophan functionalized perylene bisimide as a sensing chemosensor for mercury in aqueous solution. This complex between perylene dimide derivate (PDI/Trp) and mercury ions was evaluated and displayed to be turn on fluorescent chemosensor for the determination of biothiols in aqueous media. PDI/Trp showed fluorescence quenching in the presence of Hg2+ and the fluorescence was recovered after addition of biological thiols (cysteine, homocysteine and glutathione). Therefore, PDI/Trp can be employed as a fluorescence probe for the sequencial recognization of Hg2+ and biothiols in aqueous solution. Graphical Abstract ᅟ.

Facile and on−line colorimetric detection of Hg2+based on localized surface plasmon resonance (LSPR) of Ag nanotriangles

A rapid and sensitive colorimetric detection method for the determination of Hg2+ has been successfully developed in this research. Citrate−functionalized silver nanotriangles (AgTrngs) were synthesized via one−pot sodium borohydride method with the edge−length range of 30 − 40 nm. The obtained AgTrngs were fully characterized using UV−Vis spectrophotometry, transmission electron microscopy (TEM), energy dispersed spectroscopy (EDS) and X−ray diffractometer. The efficiency of the developed sensor was optimum at pH= 8 due to interfering effect of H+ ions for Hg2+ under acidic conditions. The successful detection of mercury in aqueous solutions in the concentration range of 10 nmol L−1–50 μmol L−1 indicated the applicability of the developed sensor for effective monitoring and controlling the level of Hg2+ in industrial effluents. The ability of Hg2+ ion to interact with Ag and form the Hg−Ag alloy (amalgam) over the surface of AgTrngs resulted in an obvious color change from blue to violet. UV−Vis spectrophotometry showed that the sensor has the limit of detection (LOD) value of as low as 4 nmol L−1 which was below the safety level of Hg2+ions (10 nmol L−1) in drinking water. The proposed method can be used for on−line determination of Hg2+ in the complex aqueous solutions.

Sensitive detection of mercury using the fluorescence resonance energy transfer between CdTe/CdS quantum dots and Rhodamine 6G

The sensitive and selective detection of mercury in aqueous solution is of paramount importance as the mercury concentration in drinking water above the threshold level set by world health organization can cause serious health issues to humans. We demonstrate a simple, facile, and cost-effective one pot synthesis route to synthesize MPA (3-mercaptopropionic acid) stabilized CdTe/CdS core-shell quantum dots and its application for detection of mercury using the fluorescence resonance energy transfer with a cationic dye, Rhodamine 6G. The quantum dots prepared via chemical reduction strategy using a combination of reducing agents, namely sodium borohydride and citric acid exhibit a high quantum efficiency (> 20% for solid state). Structural as well as luminescence studies of the prepared quantum dots were found to depend on the pH as well as the size of the quantum dots (hydrodynamic diameter ranging from 9 to 16 nm). Analysis of the fluorescence resonance energy transfer (FRET) between the prepared quantum dots and Rhodamine 6G elucidate that efficient energy transfer happens in the presence of a cetyl trimethyl ammonium bromide (CTAB) surfactant. Though the prepared CdTe/CdS quantum dots exhibit fluorescence quenching with an increase in mercury concentration and act as an “OFF-sensor,” the Rhodamine 6G-quantum dot pair employed here found to be a better approach as the inherent fluorescence of Rh6G is insensitive to mercury concentration. Our studies elucidate that the fluorescence ratio of Rh6G in a FRET pair follows a linear nature for the Stern-Volmer plot in the concentration range of Hg2+ ions (0.1 nM to 2 μM) and provide a LOD of 3.8 nM.

Utilization of Bacillus thuringiensis MC28 as a biosorbent for mercury in groundwaters from some selected gold mining communities in the Wassa West District of the Western Region of Ghana

In this study, Bacillus thuringiensis MC28 was investigated for its utilization as a potential adsorbent for mercury in aqueous solutions. The batch adsorption procedure was used to optimize the method. At optimal conditions of pH 8, 3.5 mL of organism, contact time of six days and 35 °C, 99.94–99.98% of mercury in groundwater samples were removed. The Langmuir isotherm parameters estimated by nonlinear method best fitted the adsorption data. The maximum monolayer coverage of the organism, the Langmuir constant, and the Langmuir separation factor (RL) were found to be 6.23E + 00 mg/mL, 253.82E + 03 L/mg and 3.94E − 07 respectively. The mercury removal was found to have occurred by chemisorption. The Elovich kinetic model best fitted the data and the rate determining step of the process was found to be bulk diffusion process. The thermodynamic properties viz: ΔH°, ΔS° and ΔG° of the mercury – B. thuringiensis MC28 adsorption system were estimated to be −114.80 kJ/mol, 391.42 kJ/mol and −506.22 kJ/mol respectively. Under the optimum physico – chemical conditions, the minimum energy required to initiate mercury removal was estimated to be 167.50E − 03 kJ/mol. The findings showed that, mercury removal process was exothermic, spontaneous, thermodynamically feasible, and the B. thuringiensis MC28 demonstrated remarkable affinity for mercury. Therefore, B. thuringiensis MC28 could be used as an adsorbent in water treatment procedure to remove mercury and restore mercury contaminated waters to their pristine.

7 硫黄添加処理を施した石炭の水溶液中における水銀吸着特性(改質・処理・クリーン化(1))

7 硫黄添加処理を施した石炭の水溶液中における水銀吸着特性(改質・処理・クリーン化(1))

Catalysis-reduction strategy for sensing inorganic and organic mercury based on gold nanoparticles

In view of the high biotoxicity and trace concentration of mercury (Hg) in environmental water, developing simple, ultra-sensitive and highly selective method capable of simultaneous determination of various Hg species has attracted wide attention. Here, we present a novel catalysis-reduction strategy for sensing inorganic and organic mercury in aqueous solution through the cooperative effect of AuNP-catalyzed properties and the formation of gold amalgam. For the first time, a new AuNP-catalyzed-organic reaction has been discovered and directly used for sensing Hg2+, Hg22+ and CH3Hg+ according to the change of the amount of the catalytic product induced by the deposition of Hg atoms on the surface of AuNPs. The detection limit of Hg species is 5.0pM (1 ppt), which is 3 orders of magnitude lower than the U.S. Environmental Protection Agency (EPA) limit value of Hg for drinking water (2 ppb). The high selectivity can be exceptionally achieved by the specific formation of gold amalgam. Moreover, the application for detecting tap water samples further demonstrates that this AuNP-based assay can be an excellent method used for sensing mercury at very low content in the environment.

Electrochemical detection of low concentrations of mercury in water using gold nanoparticles.

The electrochemical detection of mercury in aqueous solutions was studied at glassy carbon (GC) and indium-tin oxide (ITO) electrodes modified by gold nanoparticles (Au NPs). Two methods of modification were used: electrochemical reduction of HAuCl4 and electrostatic adsorption of Au NPs stabilized by citrate. We found that the Au NPs modified surfaces yielded higher sensitivity and sharper and more reproducible stripping peaks of Hg as compared with the bare electrodes. The effect of the modification by Au NPs on the stripping potential was examined. Interestingly, the stripping of Hg on GC and ITO modified by Au NPs occurred at the same potential as on bare GC and ITO, respectively. Only the full coverage of ITO by either electrochemically deposited Au for a long time or by vapor deposition, shifted the stripping potential more positive by ca. 0.4 V to that observed on a bare Au electrode. These and further experiments led us to conclude that the Au NPs served as nucleation sites for the deposition of Hg, whereas the GC or ITO are superior for the stripping of mercury. Hence, a combination of well-defined Au NPs on ITO or GC were found ideal for the electrochemical detection of Hg. Indeed, we achieved a remarkable detection limit of 1 μm·L(-1) of Hg using an ITO surface modified by electrostatically adsorbed Au NPs.