Extraction Of Mercury Research Articles

Baseline concentrations of mercury species within sediments from Qatar's coastal marine zone

Baseline concentration of total mercury (THg), organic extractable mercury and methylmercury (CH3Hg) concentrations in sediments from the northeastern, eastern and southeastern parts of the Arabian Gulf were assessed. Surface sediments were collected from eleven stations from the coastal waters of Qatar. All analyses were performed on homogenised samples. Total mercury analysis was performed by Cold Vapour Atomic Absorption Spectrometry (CVAAS), and methylmercury was analysed by Cold Vapour Atomic Fluorescence spectrometry (CVAFS) after aqueous phase ethylation of the extracted samples. Total mercury (THg) in sediments varied from 8.0 μg/kg to 34.3 μg/kg. Methylmercury was detected in all stations and ranged from 1.46 μg/kg to 3.10 μg/kg accounting for 5.4% to 18.4% of total mercury. Total organic carbon (TOC) ranged from 0.16 to 0.72%, while Organic extractable mercury ranged from 1.55 μg/kg to 13.3 μg/kg. Analysis, the grain size within these sediments, was carried out previously paving the way for studying the influence of these parameters on the sedimentary mercury concentration. Speciation was also assessed, as were relations between the measured mercury fractions.

Integrated pore-scale characterization of mercury injection/imbibition and isothermal adsorption/desorption experiments using dendroidal model for shales

Distinct from conventional reservoirs, shale formations have limited pore connectivity and unique pore spatial-distributions. Consequently, theoretical pore-network models developed for conventional formations are not representative of the pore topology within unconventional rocks. This paper presents a theoretical pore-network model, dendroidal model, based on the analysis of reconstructed pore-scale model extracted from Scanning Electron Microscope images. Dendroidal model is a semi-acyclic model, which characterizes the poor connectivity of void space without sacrificing the interaction between main flow paths. Dendroidal model infers pore-body distribution based on the hysteresis effect of isothermal adsorption/desorption measurements and characterizes pore-throat distribution using mercury injection capillary pressure data. The use of dual-compressibility model in pore-network model construction eliminates the effect of compressibility of both void space and matrix. Total organic carbon (TOC) content and minerology determine the composition of pore bodies and pore throats. The difference in mercury intrusion and extraction caused by trapping hysteresis and contact-angle hysteresis affects the stochastically distributed parameters, including pore-throat length, pore-throat cross-sectional morphology, coordination number and pore-body spatial distribution. We used shale core samples from Marcellus and Wolfcamp formations to validate the dendroidal models by calculating the absolute permeability without slippage effect. This newly developed pore-network model integrates aforementioned seven distinct types of experimental data to capture the realistic pore structures within shales.

Определение ионов тяжелых металлов в экстрактах корня элеутерококка колючего

The content of cadmium, mercury, zinc and cuprum ions in extracts of Eleutherococcus prickly root powder was determined by stripping voltammetry. The content of Zn2+ cations in the aqueous extracts of the plant adaptogen was below the detection limit for the analysis method used. The concentration of ions Cd2+, Pb2+ in aqueous extracts it was less than 0.0002 mg/kg. The amount of cuprum ions did not exceed 2.6 mg/kg. Consequently, the concentrations of heavy metal cations are below the MPC level (maximum permissible concentration), which allows us to speak about the toxicological safety of the plant material studied. Increasing the maceration temperature from 23 to 40 °C reduces the efficiency of the process. The possible causes of this phenomenon are discussed. The source of raw materials does not have a significant effect on the content of pollutants. For the extraction of plant materials, along with distilled water, tap water can be used, which in its performance meets the standards for the content of heavy metal ions in all areas of the city of Kazan. The maximum value of the total pollution indicator is 4.5 mg/l. It was found in tap water selected in the Vakhitovsky district of the city of Kazan. However the maximum lead content is characteristic of the water selected in the Soviet district of the city. Distillation of water is expected to reduce pollution by pollutants. However complete purification from heavy metal ions does not occur. The most intense distillation is the purification of water from cuprum ions. The minimum amount of pollutants is found in ethanolic extracts of Eleutherococcus root powder. It is obvious that ethanol, as an extractant of heavy metal cations, is less preferable than water.

Liquid–liquid extraction of mercury(II) from aqueous solution using furosemide in benzyl alcohol

A simple, efficient and economical liquid–liquid extraction method has been developed for quantitative extraction of mercury(II) from aqueous buffer solution using furosemide in benzyl alcohol. The effect of various parameters and of various anions and cations on the extraction of mercury(II) was investigated. The separation factor of mercury was quite high in the presence of a number of transition and rare earth metals at pH 3.5. Among strippants, sodium thiosulphate was found most suitable, and the recovery of mercury was noted to be 98%. The stoichiometric composition of the extracted species was found to be [Hg(FS)2].

Use of modified carbon sorbents in extracting mercury from technogenic raw materials

Heavy metal pollution of the environment is an increasingly important issue because heavy metals of both natural and technogenic origin are highly toxic and non-degradable substances. Extracting heavy metals from industrial solutions using carbon sorbents is one of the promising and effective methods providing complete extraction of the pollutants. The paper describes the research on the potential use of the modified activated carbon obtained from brown coal as a sorbent for mercury extraction. The adsorption capacity of the modified ABG (activated brown granular) sorbent has been defined for a solution with the initial ion concentration of 5-15 mg/dm3 in static conditions. Isotherms have been plotted for the initial (ABG) and modified (ABG-M) sorbents. The maximum adsorption capacity of ABG-M has been defined as 21.5 mg/g, which is 1.6 times that of ABG. The use of modified carbon sorbents in extracting heavy metals from waste waters and technogenic formations helps to achieve a high degree of purification without any additional chemical agents polluting the environment.

Adsorption, Kinetic and Thermodynamic Studies for Mercury Extraction from Water Samples Using Mesoporous Silica

Mercury is recognized internationally as an important pollutant since mercury and its compounds are persistent, bioaccumulative and toxic, and pose human and ecosystem risks. A critical aspect of mercury cycling is its bioaccumulation, mainly as methylmercury, along the contaminated water with mercury resulting in high risk of human. Adsorption of mercury from water samples on mesoporous silica, mercaptopropyl functionalysed-SBA-15 (MP-SBA-15) and diethylenetriamine functionalysed-SBA-15 (DETA-SBA-15) has been studied. SBA-15 was prepared by using Pluronic P123, PEO20PPO70PEO20 and tetraethylorthosilicate. Surface modification of SBA-15 was carried out by MP-TMS or DETA-TMS to produce MP-SBA-15 or DETA-SBA-15, respectively. SBA-15 and functionalised SBA-15 materials were characterised for BET surface area, pore size and pore volume. The adsorption kinetics and adsorption isotherms of functionalised SBA-15 for mercury were investigated. Results revealed that the adsorption kinetics were fitted by a pseudo-second-order reaction model and the adsorption thermodynamic parameters ΔH°, ΔS° and ΔE° were 42.08 kJ/mol, 210.3 J/mol.K and 7.20 kJ/mol, respectively for DETA-SBA-15; 101.85 kJ/mol, 397.7 J/mol.K and 23.28 kJ/mol, respectively for MP-SBA-15. Langmuir and Freundlich isotherm models were also applied to analyse the experimental data and to predict the relevant isotherm parameters. The best interpretation for the experimental data was given by the Langmuir isotherm equation. The results indicate that the structure of the materials affects the adsorption behavior. These materials show a potential for the application as effective and selective adsorbents for Hg(II) removal from water.

Selective solid phase extraction and preconcentration of ultra-trace inorganic mercury in water samples using 2,6-dimethyl-morpholine dithiocarbamate

ABSTRACTA sensitive and selective solid-phase spectrophotometric method for the determination of trace amounts of Hg(II) cation in water is described. A complex was created with Hg(II) using 2,6-dimethyl-morpholine dithiocarbamate (DMMDTC) to form Hg(II)–(DMMDTC) and this complex was adsorbed onto microcrystalline naphthalene (MN) and then eluted with 5% acetic acid (in ethanol) solution. A preconcentration factor of 187 and a recovery of 95% were observed at pH of 5.0 and for 10 min. of extraction. The separated Hg(II) ions were quantified by using ultraviolet-visible spectrophotometer at 490.0 nm by creating a colored complex with dithizone in Triton X-100 surfactant media. Molar absorptivity and sandell’s sensitivity for the Hg(II)-dithizone were determined as 4.96 × 105 Lmol−1cm−1 and 0.4032 µg cm−2, respectively. The detection limit (LOD) was 1.7 μg L−1 under the optimized conditions of the analytical method.

Study on Pure Mercurous Chloride Leaching with Sodium Thiosulfate

Mercurous chloride (Hg2Cl2), also known as Calomel, is a typical mercury-containing mineral found in nature. In this work, the leaching behaviour of pure mercurous chloride dissolved in pure water and in thiosulfate solution was investigated. The mercurous chloride hardly dissolved in sulfuric acid solution at pH of 3 and pure water at pH of 6.4, with the corresponding maximum Hg extraction percentage at 3.1 and 7.5% respectively. However, the Hg extraction percentage increased to 45.8% in sodium hydroxide solution at pH of 11.2. The mercury extraction percentage reached a high of 62.6% in thiosulfate solution, and the leaching kinetics results show that the activation energy is 6.6 kJ/mol. This study indicates that the thiosulfate solution can efficiently extract mercury from mercurous chloride.

Combined experimental and theoretical investigation on selective removal of mercury ions by metal organic frameworks modified with thiol groups

Highly efficient and selective extraction of mercury from wastewater is still a challenging issue for public health and ecosystem protection. Herein, defective UiO-66 modified with thiol groups (denoted as UiO-66-SH) was achieved through a facile method under mild conditions and applied for the selective extraction of mercury from aqueous solutions. UiO-66-SH displayed a fast adsorption rate for Hg(II) ions with a high pseudo-second-order rate constant of 3.4 × 10−2 g/(mg·min) and a high adsorption amount of 3.91 mmol/g. In addition, UiO-66-SH showed high adsorption performance over a broad pH range (2.3–8.0) and retained high effectiveness (>90%) after being regenerated seven times. Moreover, it displayed selective adsorption towards Hg(II) ions under the inteference of divalent metal ions (i.e., Co2+, Cd2+, Cu2+, Ni2+, Ba2+ and Mn2+). However, it’s adsorption rate decreased by an average of 30 and 40% under interfering Zn(II) and Pb(II), respectively. Experimental data and density function theory (DFT) calculations disclosed that the excellent extraction effectiveness could stem from the strong interaction between Hg(II) ions and the thiol groups in the surface of UiO-66-SH. The results of DFT calculations carried out for the capture of Ba2+, Zn2+, Pb2+, and different Hg(II) species (Hg2+ and Hg(OH)+) provided a reasonable explanation for the selectivity and the slight decrease of the adsorption rate with the increase of solution pH. UiO-66-SH also provided a high affinity for organic mercury forms (MeHg+, EtHg+ and PhHg+). Therefore, our approach to functionalize the defective UiO-66 by thiol groups would provide a new insight for mercury decontamination in the cleanup of environmental pollution.

Экогеохимия ртути в почвах и углях юга Кузбасса

Assessment for content of mercury as a toxic component of coal combustion by-product in rocks and deposit environments is aimed at identification of risks caused by impact of hazardous activities on the environment in full concordance with green chemistry concept. In this paper have been presented results of mercury content determination for the South Kuzbass coals and soils of the coal-mining area. The mercury contents in soils (30 samples) and coals (30 samples) were determined by atomic absorption method on the RA‑915+ mercury analyzer with pyrolytic attachment. The mercury content in Mezhdurechensk strip mines’ coals varies from 0.13 to 2.46 mg/kg with the average concentration of 0.57±0.10 mg/kg. The determined content exceeds the Clarke of mercury in coals by factor of 1.3 to 24.6. The mercury content in soil samples varies from 0.012 to 0.173 mg/kg with the average value of 0.057±0.007 mg/kg, which is by 1.7 times more than the average mercury content in the Earth crust. There are five locations within Mezhdurechensk city area where the mercury content in the soil exceeds 3.1–5.3 times the Clark value. During past 25 years the average mercury content in the soil has been decreased by 2.8 times. The solubility of mercury from technogenic landscapes’ soils has been studied by methods of successive acetate-ammonium and hydrochloric acid extracts. The solubility of mercury in aqueous extracts from Mezhdurechensk soils is by 2.2–2.9 times higher than the ones taken from undisturbed landscapes, in acetate-hydrochloric acid and alkaline extracts it is within the limits of content in natural soils; in strongly acidic extracts has been found the maximum solubility of mercury (30.6–84.8% from the total amount). Based on the major contribution of coal dust in the gross input of mercury into the environment of Mezhdurechensk, it is possible to expect the increasing of mercury background in and around the city caused by the growth of coal mining in the area without implementation of modern and effective methods for dust suppression.

Organic-inorganic hybrids: an efficient extractant of environmental mercury ions

A functionalized organic-inorganic hybrid is synthesized by Mannich reaction after its activation with organosilane coupling agent and subsequent conjugation with and 1-napthyl-2-thiourea (ANTU). The material is characterized by fourier transform infrared spectroscopy, elemental and thermogravimetric analysis. Its efficacy as adsorbent is tested for the extraction of low level of mercury from aqueous solutions using radiotracer technique. Various parameters affecting mercury extraction are optimized. Maximum sorption (92%) of Hg(II) ions occured at pH 6 in 30 min using 50 mg of nanohybrid as extractant. In competitive environment only chromate and fluoride increased while thiosulfate reduced its extraction efficiency. The mercury adsorption process is chemisorption in nature and follows second-order kinetic model. The sorption follows Freundlich and D–R models over a wide range of concentration studied. The maximum uptake capacity of the material is 156.7 mmolg−1.

Mercury Capture from Petroleum Using Deep Eutectic Solvents

Mercury capture is a major challenge in petroleum and natural gas processing. Recently, ionic liquids (ILs) have been introduced as mercury extractants from oil and gas. ILs yield very high mercury extraction efficiencies (>95%) from hydrocarbons, but their drawbacks include complex synthesis, toxicity, and difficult regeneration after mercury capture. In this work, a new technology using deep eutectic solvents (DESs) for elemental mercury (Hg0) extraction from hydrocarbons is demonstrated. DESs are an innovative class of designer solvents exhibiting similar properties as ILs, such as low vapor pressure and low flammability, but DESs are formed from inexpensive hydrogen-bond donor and acceptor compounds that are often biodegradable. In this work, four DESs were investigated including choline chloride:urea, choline chloride:ethylene glycol, choline chloride:levulinic acid, and betaine:levulinic acid, where the molar ratio is 1:2 in all cases. The DESs were tested for their thermal stability, density, and v...

Enhancer assisted-phytoremediation of mercury-contaminated soils by Oxalis corniculata L., and rhizosphere microorganism distribution of Oxalis corniculata L.

The present study investigated remediation of mercury-contaminated soils using Oxalis corniculata L. combined with various enhancers (sodium thiosulfate, ammonium thiosulfate, ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid). The experiment was conducted using Oxalis corniculata seedlings planted in pots containing mercury loaded soils. Investigations included analysis of soil properties, plant growth conditions, ability of the plants to accumulate and extract mercury, and rhizosphere microorganism distribution. The maximal mercury content of the aerial parts and the mercury-translocation ratio of Oxalis corniculata treated with enhancers increased compared to Oxalis corniculata without enhancers. Compared with no enhancers, the theoretical reduction in phytoremediation time was about 50%, 25%, 20% and 21% when Oxalis corniculata was treated with sodium thiosulfate (Na2S2O3), ammonium thiosulfate ((NH4)2S2O3), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA), respectively. The results indicated that the dominant species in rhizosphere soils varied with different enhancers. However, the evenness of background soils, rhizosphere soils of Oxalis corniculata, Oxalis corniculata treated with Na2S2O3, (NH4)2S2O3, EDTA and DTPA was not largely different at 0.62, 0.61, 0.57, 0.64, 0.61 and 0.63, respectively. These findings demonstrate that Oxalis corniculata treated with Na2S2O3 has the potential to recover and reclaim mercury-contaminated soils in pots.

Removal and confinement of Hg(II) by polyurethane foam functionalized with potassium O-ethyldithiocarbonate

Polyurethane foam functionalized with potassium O-ethyldithiocarbonate was evaluated as an extractant material for Hg(II). Several parameters such as pH, mass amount and extraction time were studied. Under the best conditions, a 86% of mercury extraction was achieved. Dubinin–Radushkevich isotherm model indicated that the nature of interaction between functionalized foam and Hg(II) is chemical. Regarding interferents, metallic ions Ag(I) and Sn(IV) have a significant influence on the Hg extraction percentage. In the case of silver, it had a synergistic effect increasing the percentage of mercury due to a metallophilic interaction. Also, once the mercury was extracted, its leaching from the functionalized polyurethane foam was evaluated by means of two sequential extraction procedures. In this way, the functionalized foam emerges as a good material for the removal and confinement of chemical species. Obtained results show that mercury extraction is successful even from complex solution and that mercury-foam material is stable under extreme chemical and temperature conditions.

漢方処方エキス中のヒ素，カドミウム，鉛及び水銀の実態調査

漢方処方エキス中のヒ素，カドミウム，鉛及び水銀の実態調査

Introduction of Molecular Building Blocks to Improve the Stability of Metal-Organic Frameworks for Efficient Mercury Removal.

With expanding human needs, many heavy metals were mined, smelted, processed, and manufactured for commercialization, which caused serious environmental pollutions. Currently, many adsorption materials are applied in the field of adsorption of heavy metals. Among them, the principle of many mercury adsorbents is based on the interaction between mercury and sulfur. Here, a S-containing metal-organic framework NENU-400 was synthesized for effective mercury extraction. Unfortunately, the skeleton of NENU-400 collapsed easily when exposed to the mercury liquid solution. To improve the stability, a synthetic strategy installing molecular building blocks (MBBs) into the channels was used. Modified by the MBBs, a more stable nanoporous framework was synthesized, which not only exhibits a high capacity of saturation mercury uptake but also shows high selectivity and efficient recyclability.

Determination of Mercury(II) in Drinking Water by Total Reflection X-ray Fluorescence Spectrometry and Liquid–Liquid Microextraction

ABSTRACTThe total reflection X-ray fluorescence determination of mercury(II) in drinking water at concentrations of 7 × 10−2 to 3.0 µg/L is reported. The mercury(II) preconcentration protocol includes directly suspended droplet microextraction with benzene as a molecular iodine complex. The proposed approach is highly selective. The elements Cr, Mn, Fe, Co, Ni, Zn, and Pb at concentrations up to 0.1 g/L did not interfere with the extraction of trace mercury(II). The method is characterized by high sensitivity (limit of detection of 21 ng/L) and suitable reproducibility (relative standard deviation of 0.12 for 100 ng/L). The accuracy of the results was confirmed by recovery and the method of standard addition.

Efficient mercury recovery from mercuric-thiosulfate solutions by ultraviolet photolysis

Mercury-containing wastes are hazardous due to the high toxicity and bio-accumulative effect of mercury. Examples of mercury-containing wastes include fluorescent light bulbs, thermostats, and thermometers. Recently, several aqueous-phase methods have been developed to extract mercury from mercury-containing wastes. However, the slow kinetics of mercury recovery limits the application of the aqueous-based technology. Here we designed a method of mercury recovery from a mercuric-thiosulfate solution assisted by ultraviolet photolysis. We evaluated the effect of initial pH, thiosulfate concentration and temperature on ultraviolet photolysis. The precipitation products were characterized by X-ray diffraction and X-ray photoelectron spectroscopy (XPS). Results show a mercury recovery ratio of 87.94% after ultraviolet photolysis during 240 min. We conclude that mercury can be efficiently recovered from mercuric-thiosulfate complex solutions by ultraviolet photolysis.

Synthesis of highly porous inorganic adsorbents derived from metal-organic frameworks and their application in efficient elimination of mercury(II)

Innovative solid-phase adsorbent is needed urgently for highly efficient extraction of mercury (Hg(II)) from aqueous solution. Herein, highly porous inorganic materials, including ZrOx, ZrOxyPhos and ZrSulf, were obtained from topotactic transformations of metal–organic frameworks (MOFs) via a facile ligand extraction process, which preserved the original MOF morphology and introduced useful functionalities. ZrOx and ZrOxyPhos exhibited high adsorption efficiency for Hg(II). And ZrSulf showed fastest adsorption kinetics (1.1 × 10−2 g/(mg min)) and highest adsorption capacity (824 mg/g) among the obtained three inorganic materials due to the presence of accessible sulfur-based functionality, which surpassed most of other benchmark porous adsorbents. Moreover, ZrSulf showed good regeneration ability and excellent selectivity for Hg(II) in the presence of other coexisting metal ions, such as Cd(II), Ni(II), Co(II), Mn(II) and Zn(II), and other inorganic cations, such as K+ and Na+. The excellent adsorption performance of ZrSulf towards Hg(II) can be traceable to the covalent bond formation with sulfur-based functionality combined with ion exchange with Na. Given its low-cost and easy preparation nature, ZrSulf could be potentially valuable candidates for the elimination of Hg(II) from aqueous media. Changing the MOF templates and using different digest solutions will introduce different metal and structural possibilities, which demonstrates the potential of such ligand extraction method for synthesizing porous inorganic adsorbents for heavy metal ion decontamination.

Two frequency ultrasound in preparation of the samples of natural brines to determine mercury by “cold vapor” absorption

Using of two-frequency ultrasound (US) in preparation of the samples of brines to determine Mercury by “cold vapor” absorption was studied. At this process US was used for: to destruct organic Mercury compounds, to carry out the process of Mercury extraction by ditizone in Carbon tetrachloride solution and to destruction and homohenization of Mercury extracts. It was found out by experiment that: to destruct organic Mercury compounds, also to destruct and homohenizate Mercury extracts using of simultaneous action of US of high and low frequencies is optimal. Comparison of the results, obtained with use of US of high (0.9-5.0 МHz)and low (18-100 kHz) frequencies show us that the best results were obtained with use of US of high (1.5-2.5 МHz) frequency. Change of frequency of low frequency US from 18 up to 100 kHz does not make the significant influence on the value of Mercury extraction at destruction of organic Mercury compounds. At this process intensity of low frequency US should be 1.5-2.5 W/cm2, of high frequency-2.5-3.0 W/cm2. The dependence between the degree of Mercury extraction and contain of fulvic acids (FA) in brines was determined. It was shown that for brines with contains of FA up to 10 mg/kg, the degree of Mercury extraction is 95-98%, for brines with contains of FA 10-20 mg/kg, the degree of Mercury extraction is 90-95%, and for brines with contains of FA above 20 mg/кg, the degree of Mercury extraction less than 90%. At using the standard methodic to determine Mercury in brines with contains of FA above 30 mg/kg, the degree of Mercury extraction less than 80%. At the destruction of Mercury extracts (Mercury (ІІ) dithizonates in Carbon tetrachloride) the maximal possible value of Mercury extraction was observed at simultaneous action of US of two frequencies- 18-100 kHz and intensity 1.5-2.5 W/cm2 , of frequency- 1.0-2.5 МHz and intensity 2.5-3.0 W/cm2 during 15-30 s. At Mercury extraction under US action the maximal possible value of Mercury extraction was observed at frequency- 500-800 kHz and intensity 0.3-0.5 W/cm2 during 1-3 min. The methodic to determine Mercury in natural brines with low end 0.0005 mkg/l was developed. The standard deviation of the obtained results is 0.06-0.09, according to standard methodic Sr ≥0.12. Simplification of reproducibility of the obtained results let us to control the tendency of fluctuations of Mercury content in natural brines as a result of anthropogenic pollution also as a result to using brines from various sources from various depth of the well.