Mercury Adsorption Research Articles

Inverse Vulcanization of Activated Norbornenyl Esters-A Versatile Platform for Functional Sulfur Polymers.

Elemental sulfur has shown to be a promising alternative feedstock for development of novel polymeric materials with high sulfur content. However, the utilization of inverse vulcanized polymers is restricted by the limitation of functional comonomers suitable for an inverse vulcanization. Control over properties and structure of inverse vulcanized polymers still poses a challenge to current research due to the dynamic nature of sulfur-sulfur bonds and high temperature of inverse vulcanization reactions. In here, we report for the first time the inverse vulcanization of norbornenyl pentafluorophenyl ester (NB-PFPE), allowing for post-modification of inverse vulcanized polymers via amidation of reactive PFP esters to yield high sulfur content polymers under mild conditions. Amidation of the precursor material with three functional primary amines (α-amino-ω-methoxy polyethylene glycol, aminopropyl trimethoxy silane, allylamine) was investigated. The resulting materials were applicable as sulfur containing poly(ethylene glycol) nanoparticles in aqueous environment. Cross-linked mercury adsorbents, sulfur surface coatings, and high-sulfur content networks with predictable thermal properties were achievable using aminopropyl trimethoxy silane and allylamine for post-polymerization modification, respectively. With the broad range of different amines available and applicable for post-polymerization modification, the versatility of poly(sulfur-random-NB-PFPE) as a platform precursor polymer for novel specialized sulfur containing materials was showcased.

An Innovative Approach for Elemental Mercury Adsorption Using X-ray Irradiation and Electrospun Nylon/Chitosan Nanofibers.

A novel approach was proposed, utilizing an electrical field and X-ray irradiation to oxidize elemental mercury (Hg0) and encapsulate it within a nanofibrous mat made of Polyamide 6/Chitosan. The X-rays contributed significantly to the conversion of Hg0 into Hg+ by producing electrons through the photoionization of gas molecules. The positive and negative pole electrodes generated an electric field that exerted a magnetic force, resulting in the redirection of oxidized elemental mercury towards the negative pole electrode, which was coupled with a Polyamide 6/Chitosan nanofiber mat. The evaluation of the Polyamide 6/Chitosan nanofibers exposed to oxidized mercury showed that the mercury, found in the steam of a specially designed filtration device, was captured in two different forms. Firstly, it was chemically bonded with concentrations ranging from 0.2 to 10 ng of Hg in total. Secondly, it was retained on the surface of the Polyamide 6/Chitosan nanofibers with a concentration of 10 microg/m3 of Hg per minute. Nevertheless, a concentration of 10 microg/m3 of mercury is considered significant, given that the emission levels of mercury from each coal power plant typically vary from approximately 4.72 to 44.07 microg/m3. Thus, this research presents a viable approach to reducing mercury emissions from coal-fired power plants, which could result in lower operational expenses and less secondary environmental effects.

Efficient gaseous mercury removal by nano-amorphous red selenium and recycling design of HgSe nanoparticles

Mercury, is a highly toxic chemical that poses serious hazards to both humans and the environment to be controlled. In this paper, Different Se forms have great varying performance of gaseous mercury(Hg0) removal. Nano-amorphous red selenium(ar-Se) has an excellent adsorption effect on Hg0 successfully synthesized by one step oxidation reduction. The factors to ar-Se such as flue gas components, temperature, gas flow rate, and pH affecting mercury removal effect were investigated. The results showed that the ar-Se achieved high utilization (>74.9 %) and mercury affinity (>97 %) at room temperature. Mercury removal rate was almost unaffected by gas components at room temperature, and it kept a stable mercury adsorption in long-time gaseous mercury recovery experiments, which responded to the high electron activity on its surface. Long-range periodic structures with no regular atomic arrangement decide ar-Se in an active state having high specific surface area, surface activity, good dispersion. The HgSe nanoparticles(NPs) was formed by the adsorption of gaseous mercury onto ar-Se. For further recycling of mercury, a recovery route for HgSe has been proposed and oxygen was found having a strong influence on the production of HgSe.

Designing of SrFe2O4-decorated sulfur-MXene for super-fast adsorption of mercury

Needless to say, the severity of water pollution reached its peak, raising awareness to find a convenient strategy for improving this troublesome situation. Mercury (Hg2+) is listed as the 6th among the most jeopardous heavy metals. In this respect, MXene was double modified by; (i) Sulfur-doping to boost its affinity toward Hg2+, and then (ii) blending sulfur-doping MXene with the magnetic SrFe2O4 that could provide excellent recyclability and adsorption aptitude. Characterization analyses like XRD, XPS, and FTIR were applied to assure the well-fabrication of SrFe2O4/S-MXene and investigate its crystallinity, chemical composition, and function groups. The morphological structure of SrFe2O4/S-MXene was shown via SEM. Besides, the magnetization character and net surface charge were deduced by VSM and ZP measurements, respectively. Interestingly, it was observed superior adsorbability of SrFe2O4/S-MXene towards Hg2+ where qmax attained 838.99 mg/g during 15 min merely at pH 6 and 25 °C. Equilibrium isotherms elucidated the appropriateness of Freundlich and Langmuir to model the Hg2+ adsorption onto SrFe2O4/S-MXene. Additionally, kinetic analysis denoted that the adsorption data of Hg2+ obeyed the PSO. The adsorption mechanism of Hg2+ onto SrFe2O4/S-MXene was assumed to proceed by electrostatic interaction, surface complexation, and reduction reaction.

Analysis of mercury removal and sulfur resistance of CrOx-MnOx-SnOx-TiO2 catalysts

To investigate the ability of CrOx-MnOx-SnOx-TiO2 composite catalysts to adsorb and remove substances, particularly in the presence or absence of SO2, Sn was included in CrMnTi catalysts throughout the production procedure. The incorporation of Sn was found to boost the specific surface area, optimize the pore structure, and augment the number of active sites, as determined using characterization methods such as XRD, XPS, and BET. When Sn metal oxides were included in MnTi catalysts individually, the resulting MnSnTi catalysts showed a limited capacity to remove Hg0. However, adding Sn metal oxides allowed for widening the temperature range in which the catalysts found successful application. This will increase the range of application temperature and is of very successful importance for large-scale commercial applications. They demonstrate that, by incorporating chromium metal oxides, the oxygen Oβ reactivity within the MnSnTi catalyst increases, resulting in a greatly improved capacity for Hg0 removal and its resistance to sulfur. This study details the combined effect of Cr, Mn, and Sn ternary composite oxides on sulfur resistance and mercury removal. The result shows that Sn promotes the strengthening of both the physical properties of the catalyst and the adsorption of mercury while also assisting in the dispersion of the catalyst. Cr enhances the ability of the catalyst to transfer electrons while in oxidation and, at the same time, favours the remaining high valence of Mn. Mn supports the catalyst for oxidizing mercury by changing its multivalent state. The CrMnSnTi catalysts have exceptional efficacy in removing mercury and possess excellent resistance to sulfur, making them an ideal catalytic option for industrial demercury removal. The catalysts exhibited excellent efficacy in removing mercury and showed strong sulfur resistance.

Effect of vermiculite-modified biochar on carbon sequestration potential, mercury adsorption stability, and economics

Effect of vermiculite-modified biochar on carbon sequestration potential, mercury adsorption stability, and economics

Probing the potential of mercury removal by covalently immobilized phycobiliproteins onto the surface of chitosan beads

Mercury emissions represent a significant risk to the environment and human health. Mercury is persistent and can circulate in the environment for thousands of years, which is why treating this toxic metal is important. Chitosan polymer is easily obtainable, and it has good mercury adsorption characteristics. This study aimed to improve its capabilities to absorb mercury by immobilizing phycobiliproteins (PBPs) onto the surface of chitosan beads (chitosan–PBPs). Phycobiliproteins, light-harvesting proteins from algae and cyanobacteria, have several industrially essential applications. These proteins can bind heavy metals with high affinities. Protein extracts obtained from both Arthrospira platensis, with C-phycocyanin (C-PC) as the primary protein, and Porphyra yezoensis, with R-phycocyanin (R-PC) and R-phycoerythrin (R-PE) as the dominant PBPs, were covalently immobilized onto chitosan beads. Beads with immobilized PBPs were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. Binding analysis showed that, on average, each chitosan bead weighed 20 mg and immobilized 63.54 μg of PBPs from Spirulina and 44.12 μg of PBPs from Porphyra. Immobilized proteins were still in their native state, with no visible color change months after immobilization. Chitosan–PBPs and chitosan alone were tested for mercury adsorption at pH 4 and pH 7 by atomic absorption spectroscopy. The tested concentration range of mercury was from 1 to 70 ppm. Affinity, calculated using Henry's binding isotherm, of chitosan–PBPs for mercury was twice as much higher at both pH values than chitosan alone. Furthermore, chitosan-PBP beads were able to absorb more mercury than chitosan alone. These results showed that the covalent immobilization of PBPs onto chitosan improves its mercury adsorption characteristics and creates a more efficient eco-friendly adsorbent to potentially remove mercury ions in the tested concentration range from polluted waters.

Mercury Adsorption and Oxidation Performance of an Iron-Based Oxygen Carrier during Coal Chemical Looping Process.

During chemical looping combustion (CLC) and chemical looping gasification (CLG) of coal, the release, migration, and speciation of mercury in coal are significantly influenced by oxygen-carrier materials; however, the underlying mechanism remains inadequately addressed. In this work, the effect of a typical iron-based oxygen carrier on the release behavior of mercury from a bituminous coal and a lignite was investigated based on the Ontario-Hydro method. It is found that the effect of the iron-based oxygen carrier is attributed to three aspects: the enhanced release rate of mercury from coal, the adsorption of the released mercury, and the oxidization of gaseous Hg0 into Hg2+. With the increasing temperature, the adsorbance of mercury by the iron-based oxygen carrier decreases, while the oxidation of mercury enhances. Even at 900 °C, the adsorbance of mercury by the oxygen carrier remained at 0.1687 g/g, with a relative content of Hg2+ at 22.55%. Additionally, it was observed that iron-based oxygen carriers can physically absorb both Hg0 and Hg2+, while chemisorption refers to complex-compound formation between the iron-based oxygen carrier and mercury.

A promotion strategy of enhancing the mercury removal in Shewanella oneidensis MR-1 based on the mercury absorption and electronic consumption via mer operon

Shewanella oneidensis (S. oneidensis) bacteria have bioremediation capabilities for various heavy metals, however, their repertoire of mercury-removal proteins is limited, restricting their effectiveness in mercury remediation. In this study, the integration of an exogenous mer operon into S. oneidensis expanded the range of mercury-removal proteins, significantly boosting both mercury tolerance and removal efficiency. The engineering bacteria (MR-mer) exhibited growth in a 180 mg/L Hg2+ solution, showing a 40% increase in tolerance over S. oneidensis. In a liquid medium with 50 mg/L Hg2+, the MR-mer strain achieved 73% mercury removal efficiency, outperforming the original strain by 50%, and facilitated Hg0 formation on the cell membrane. Extensive analysis of transmembrane structures and Fourier analysis revealed that mer operon proteins might target the cell membrane, modifying its functional group contents to enhance mercury adsorption. Additionally, the absence of the key protein OmcA in the electron transport chain led to a 30% reduction in Hg2+ removal capacity. This suggests that S. oneidensis transfers electrons to the cell surface through this chain, providing electrons for Hg2+ reduction. In conclusion, the mer operon, targeting the cell membrane in MR-mer strain, synergizes with the electron transport chain to markedly elevate Hg2+ removal capability. This approach not only augments Shewanella's mercury biodegradation capacity, but also offers novel perspectives for microbial heavy metal pollutant removal.

Investigation of elemental mercury removal performance and mechanism of rice straw biochars from a fluidized bed pyrolysis system impregnated by NH4Br

To remove Hg0 from flue gas efficiently and economically, the rice straw biochars prepared in a fluidized bed pyrolysis system and then modified with NH4Br are employed as the sorbents. The mercury adsorption capacity of Br-modified biochar (1786.85 μg/g) is superior to that of activated carbon (207 μg/g), which indicates Br-modified rice straw biochar sorbent displays higher Hg0 adsorption efficiency and can replace high-cost activated carbon. The sorbents are characterized by Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The effects of pyrolysis temperature, pyrolysis atmosphere, reaction temperature, the components of flue gas (O2, NO and SO2) on mercury removal efficiency, kinetics, thermodynamics and mercury removal mechanism are investigated. The results indicate elevating pyrolysis temperature and oxygen content significantly enhance the Hg0 removal efficiency. The Hg0 adsorption process is better fitted by pseudo-second-order kinetic model and proves a spontaneous endothermic process. The presence of O2 and NO in flue gas enhances Hg0 adsorption, while the presence of SO2 restrains it. After Hg0 adsorption, the peak area ratio of C=O (288.5 eV) and C-Br (69.1 eV) by Br-modified rice straw biochars produced under 8 %O2 and 500 °C atmosphere decreases from 17.03 % and 70.14 % to 6.55 % and 50.50 %, respectively, while that of Br− (68.1 eV) increases from 29.86 % to 48.50 %, indicating the surface O* and Br* species are responsible for Hg0 removal, and the products are mainly HgO and HgBr2. This work provides a kind of cost-effective Hg0 removal sorbent and explores the mechanism of Hg0 removal by Br-modified biochars.

In-situ low-temperature sulfur CVD on metal sulfides with SO2 to realize self-sustained adsorption of mercury

Capturing gaseous mercury (Hg0) from sulfur dioxide (SO2)-containing flue gases remains a common yet persistently challenge. Here we introduce a low-temperature sulfur chemical vapor deposition (S-CVD) technique that effectively converts SO2, with intermittently introduced H2S, into deposited sulfur (Sd0) on metal sulfides (MS), facilitating self-sustained adsorption of Hg0. ZnS, as a representative MS model, undergoes a decrease in the coordination number of Zn–S from 3.9 to 3.5 after Sd0 deposition, accompanied by the generation of unsaturated-coordinated polysulfide species (Sn2–, named Sd*) with significantly enhanced Hg0 adsorption performance. Surprisingly, the adsorption product, HgS (ZnS@HgS), can serve as a fresh interface for the activation of Sd0 to Sd* through the S-CVD method, thereby achieving a self-sustained Hg0 adsorption capacity exceeding 300 mg g−1 without saturation limitations. Theoretical calculations substantiate the self-sustained adsorption mechanism that S8 ring on both ZnS and ZnS@HgS can be activated to chemical bond S4 chain, exhibiting a stronger Hg0 adsorption energy than pristine ones. Importantly, this S-CVD strategy is applicable to the in-situ activation of synthetic or natural MS containing chalcophile metal elements for Hg0 removal and also holds potential applications for various purposes requiring MS adsorbents.

Thiol-functionalized cellulose for mercury polluted water remediation: Synthesis and study of the adsorption properties

Mercury pollution poses a global health threat due to its high toxicity, especially in seafood where it accumulates through various pathways. Developing effective and affordable technologies for mercury removal from water is crucial. Adsorption stands out as a promising method, but creating low-cost materials with high selectivity and capacity for mercury adsorption is challenging.Here we show a sustainable method to synthesize low-cost sulfhydrylated cellulose with ethylene sulfide functionalities bonded glucose units. Thiol-functionalized cellulose exhibits exceptional adsorption capacity (1325 mg g−1) and selectivity for Hg(II) over other heavy metals (Co, Cu, Zn, Pb) and common cations (Ca++, Mg++) found in natural waters. It performs efficiently across a wide pH range and different aqueous matrices, including wastewater, and can be regenerated and reused multiple times without significant loss of performance. This approach offers a promising solution for addressing mercury contamination in water sources.

Reinventing waste: Transforming discarded optical discs into polycarbonate-organosilane adsorbent for effective removal of mercury(II) in water

Polycarbonate, renowned for its versatile properties, has become indispensable in numerous domestic applications. However, the escalating rates of consumption and disposal raise significant concerns for sustainable development. Of particular concern is the inadequate management of obsolete optical discs, which pose a serious environmental threat due to the non-biodegradable polycarbonate component. To address this challenge, this study aimed to repurpose polycarbonate derived from optical disc waste into adsorbent materials using 3-aminopropyl triethoxysilane (APTES) coupling. The waste-derived products underwent comprehensive characterization employing Fourier transform infrared spectroscopy, field emission-scanning electron microscopy, energy dispersive X-ray spectroscopy, Brunauer-Emmett-Teller, and Barrett-Joyner-Halenda techniques. Additionally, batch experiments were conducted to evaluate the mercury(II) adsorption behaviours. The successful immobilisation of APTES on polycarbonate surfaces was confirmed by the detection of nitrogen, silicon, and urethane groups. Notably, the product modified with 3 mL of APTES exhibited the highest surface area (61.992 m2 g−1), suggesting its potential for the adsorptive removal of mercury(II). Analysis based on the Langmuir (R2 =0.9824) and Redlich-Peterson (R2 =0.9834) isotherm models suggested a predominantly monolayer adsorption mechanism with an estimated maximum capacity of 1.284 mg g–1, while the adsorption process followed pseudo second-order kinetics (R2 =0.9998). The results highlight the efficacy of waste-derived polycarbonate-organosilane adsorbents in removing mercury(II) from diverse water matrices, rendering them attractive from both economic and environmental sustainability perspectives.

Evaluation of sodium thiosulfate activated carbon for high-performance mercury removal from aqueous solutions

The current study presents a novel approach for the synthesis of activated carbon that is both environmentally benign and efficient in removing mercury from aqueous solutions. Activated carbon was produced by utilizing walnut shells as a renewable precursor and sodium thiosulfate as a benign activating agent. This approach effectively addressed environmental concerns traditionally associated with activated carbon fabrication. The resulting product exhibited a BET surface area of 451.1 m2/g and a total pore volume of 0.303 cm3/g. Comprehensive kinetic and equilibrium studies illustrated the underlying mechanisms governing mercury adsorption. Advanced characterization techniques, including SEM, EDX, XPS, and N2 adsorption/desorption isotherms, were employed to provide detailed insights into the adsorption process. The maximum adsorption capacity demonstrated by the synthesized AC is 164.4 mg/g under the following experimental conditions: 35 °C temperature, pH solution of ≈ 2, 0.02 g mass, and 180 RPM of mechanical shaking. The process was effectively described by the Freundlich isotherm and pseudo-second-order kinetics, which emphasized the significance of both chemical and physical adsorption.

Fluorescent dendritic fibrous nanosilica@chitosan porous composite microbeads: Selective and sensitive probes and removal adsorbents for Hg2+/Hg+ ions

Dendritic fibrous nano-silica (DFNS) possesses unique porous structure, making it an outstanding candidate for heavy metal adsorption and separation. It is interesting to introduce natural polymer (chitosan) into DFNS and produce natural materials-based porous DFNS. Initially, in this work, DFNS underwent modification to enlarge size and enrich with -C≡C bonds. And then, NH2-naphthalimide fluorophore was click-reacted with the modified DFNS, forming fluorescent DFNS (FL-DFNS). Eventually, chitosan was integrated into FL-DFNS using diacyl chloride, generating the organic–inorganic fluorescent composite micro-beads (FL-DFNS@CS-3). FL-DFNS acts as a “turn on” sensor for Hg2+/Hg+ ions, showing up to 5 times fluorescence increase. Also, it exhibited effective mercury adsorption. Due to its porous structure, it demonstrated good performance in adsorbing and separating Hg2+/Hg+ ions, achieving removal ratios of 98.8 % and 96.1 %, and adsorption capacities of 196.2 mg/g and 180.4 mg/g, respectively. It reached effective adsorption equilibrium within 15 min and was reusable up to seven times. Overall, this work confirms the practical applicability of FL-DFNS and FL-DFNS@CS micro-beads for identifying and removing Hg2+/Hg+ ions. Further exploration is worthy to explore its potential in environmental science and engineering.

One-step synthesis of a core-shell structured biochar using algae (Chlorella) powder and ferric sulfate for immobilizing Hg(II)

Mercury (Hg) pollution poses a significant environmental challenge. One promising method for its removal is the sorption of mercuric ions using biochar. FeS-doped biochar (FBC) exhibits effective mercury adsorption, however may release excess iron into the surrounding water. To address this issue, a novel magnetic pyrrhotite/magnetite-doped biochar with a core-shell structure was synthesized for the adsorption of 2-valent mercury (Hg(II)). The proposed synthesis process involved the use of algae powder and ferric sulfate in a one-step method. By varying the ratio of ferric sulfate and alga powder (within the range of 0.18 - 2.5) had a notable impact on the composition of FBC. As the ferric sulfate content increased, the FBC exhibited a higher concentration of oxygen-containing groups. To assess the adsorption capacity, Langmuir and Freundlich adsorption models were applied to the experimental data. The most effective adsorption was achieved with FBC-4, reaching a maximum capacity (Qm) of 95.51 mg/g. In particular, at low Hg(II) concentrations, FBC-5 demonstrated the ability to reduce Hg(II) concentrations to less than 0.05 mg/L within 30 min. Additionally, the stability of FBC was confirmed within the pH range of 3.8 - 7.2. The study also introduced a model to analyze the adsorption preference for different Hg(II) species. Calomel was identified in the mercury saturated FBC, whereas the core-shell structure exhibited excellent conductivity, which most likely contributed to the minimal release of iron. In summary, this research presents a novel and promising method for synthesizing core-shell structured biochar and provides a novel approach to explore the adsorption contribution of different metal species.

Assessment and modeling of mercury adsorption on carbon-based adsorbents prepared from Jacaranda mimosifolia and guava biomass via pyrolysis and hydrothermal carbonization

Abstract The mercury adsorption properties of carbon-based materials prepared from jacaranda (Jacaranda mimosifolia) and guava (Psidium guajava) seed wastes are reported and compared in this paper. These adsorbent samples were obtained via pyrolysis and hydrothermal carbonization. Mercury adsorption equilibrium was studied at pH 4 and 20–40 °C, and the adsorption enthalpy changes were calculated for all adsorbent samples. The results showed that jacaranda-based materials contained a higher amount of acidic functional groups than guava seed-based adsorbents, and consequently, their mercury adsorption properties were better. The surface area of these adsorbents was <10 m2/g thus being classified as low-porosity materials. Elemental analysis indicated that all adsorbents were mainly composed of oxygen (4–25%) and carbon (75–95%). The calculated adsorption capacities at saturation of the best adsorbent were 18.05–30.09 mg/g under the tested experimental conditions. Statistical physics calculations also indicated that the adsorption mechanism of HgCl2 species was multi-molecular and endothermic. Ligand exchange and van der Waals forces were involved in generating the mercury–adsorbent interface. These results highlight the importance of comparing and optimizing biomass thermochemical conversion routes to tailor the surface properties of adsorbents used for water purification.

Effect of C-Cl functional groups on adsorption and desorption of elemental mercury over an ordered mesoporous carbon modified with C-Cl functional groups

Wet desorption presents an environmentally sustainable approach for the disposal of deactivated elemental mercury (Hg0) removal adsorbents. However, the prevalence of insoluble Hg compounds in the adsorption products poses a significant impediment to the wet desorption process. In this work, an ordered mesoporous carbon modified with C-Cl functional groups (OMC-Cl) was synthesized via the evaporation-induced self-assembly (EISA) method. It has a high specific surface area (∼630 m2/g), large pore volume (∼0.64 cm3/g), and uniform pore size (∼22.0 nm). The presence of C-Cl functional groups provides a remarkable adsorption capacity to the adsorbent, exhibiting high adsorption efficiency in various adsorption atmospheres (96.8 % in pure N2; 91.7 % in N2 + H2S) and promoting the prevalence of soluble HgCl2 in the adsorption product. Density functional theory analysis has elucidated that the C-Cl functional groups exerted inhibitory effects on the formation of HgO and HgS mainly by weakening the adsorption process of Hg0 on C = O and C-S. The desorption efficiencies of adsorption products in the above atmospheres in HCl solution (0.5 mol/L) achieved 95.4 % and 81.3 %, respectively. The high concentration of H+ ions serves to prevent the re-adsorption of Hg2+ by the -SH generated during the adsorption process. Furthermore, the adsorbent desorbed in HCl solution manifests substantial potential for recyclability. This study introduces a novel approach for efficient wet desorption in terms of designing active sites to modulate the adsorption products and pore structures to facilitate mass transfer.

MERCURY (II) ADSORPTION ON MINERALS OF MAIKOP SERIES ROCKS AND MUD VOLCANO CLAYS

The acid-base properties of the surface of the Maikop series clays and mud volcano clays, as well as their adsorption properties with respect to mercury (II) ions, were studied. It is shown that pH PZC for the former is 7.1 on average; for the second — 9.0. The pH PZC value for mud volcano clays is consistent with the pH values in the waters of mud volcanoes in the Kerch-Taman region. When the mass ratio of the sorbent and solution is 1:900, adsorption equilibrium occurs after 4 days with active stirring. Experimental data on mercury adsorption from NaCl–NaHCO 3 solution on natural sorbents are best described by the Redlich-Peterson and Toth equations. The process of mercury adsorption on clays of the Maikop series is more intense than on mud volcano clays.

Efficient and selective capture of various mercury species from water using an exfoliated thiocellulose

The primary challenge in mercury (Hg) adsorbents for large-scale practical applications is to achieve the balance between performance and economy. This work attempts to address this issue by synthesizing an exfoliated thiocellulose (CU-SH) with high thiol density and hierarchical porosity using in-situ ligands grafting combined with chemical stripping. The prepared CU-SH shows remarkable physical stability and chemical resistance, and the micron sized fiber is conducive to separation from water. Hg(II) adsorption tests in water demonstrate that CU-SH has broad working pH range (1−12), fast kinetics (0.64 g/(mg‧min)), high adsorption capacity (652.9 mg/g), outstanding selectivity (Kd = 6.2 × 106 mg/L), and excellent reusability (R > 95 % after 20 cycles). Importantly, CU-SH exhibits good resistance to various coexisting ions and organic matter, and can efficiently remove Hg(II) from different real water. CU-SH can be made into a Point of Use (POU) device for continuous and efficient removal of Hg(II) from drinking water. 0.1 g CU-SH filled device can purify 3.2 L of Hg(II) (0.5 ppm) contaminated tap water before the breakthrough point of 2 ppb. Moreover, CU-SH also reveals good adsorption affinity for Hg-dissolved organic matter complexes (Hg(II)-DOM) in water, chloro(phenyl)mercury (PMC) in organic media and Hg0 vapor in air, suggesting the great practical potential of CU-SH.