Removal Of Hg Research Articles

Tuning the coordination environment of sulfur on carbon surface via doping with iron for high-capacity gaseous elemental mercury capture

Enhancement of the formation of unsaturated short-chain sulfur represents the key point in enhancing the gaseous elemental mercury (Hg0) capture by sulfur-based sorbents, and yet the sulfur often agglomerates into long-chain species. Herein, by doping with iron cation as the regulator of the coordination environment of sulfur, the long-chain sulfur was successfully converted into short-chain sulfur on carbon. The iron-sulfur loaded carbon shows a high Hg0 adsorption capacity of 72.8 mg·g−1 (80 % breakthrough) and a low cost of $42.09/kg Hg, which are superior to various sulfur modified carbons and metal sulfides. The iron can not only immobilize more amount of sulfur on carbon surface, but also break the S-S bonds. The double interaction of iron and carbon with sulfur facilitates the formation of short-chain sulfur species for Hg0 adsorption. Density functional calculations suggest that S, Fe and C sites on surface are active centers for Hg adsorption. The Hg can tri-coordinate with S, Fe and C sites, which gives a high adsorption energy of − 219.3 kJ‧mol−1, confirming the strong reaction. This work provides a new in insights into the regulation of the coordination environment of sulfur, which allows the designing of high-capacity and low-cost sorbents for gaseous Hg0 removal.

Lithium manganite anchored on mesoporous ceria photocatalyst for removal of Hg(II) ions from aqueous solution under visible illumination

The development of effective photocatalysts is critical for the photo/redox reaction of noxious Hg(II) ions and Hgo in environmental engineering and purification. In this contribution, Li2MnO3 nanoparticles (NPs) were anchored mesoporous CeO2 networks to design photocatalysts with high harvest of visible light, and the obtained Li2MnO3/CeO2 nanocomposites were utilized for photoreduction of Hg(II) ions under visible illumination. The TEM and XRD results showed the formation of Li2MnO3 and CeO2 with the monoclinic and cubic fluorite structures, and the particle size is about 10–20 nm. The enhancement of light absorption of Li2MnO3/CeO2 nanocomposites could create considerable photoinduced carriers during the photocatalytic reactions. The incorporation of Li2MnO3 and CeO2 NPs demonstrated outstanding photocatalytic performance compared with pristine CeO2 NPs, and the optimum 9%Li2MnO3/CeO2 nanocomposite achieved 98 % of the reduction Hg(II) ability within 60 min. The rate constant for 9 % Li2MnO3/CeO2 photocatalyst is ∼ 6.47 and 3.85 times greater than Li2MnO3 and CeO2 NPs. The superior photocatalytic performance of Li2MnO3/CeO2 nanocomposites was ascribed to the efficient separation of photocarriers due to the formation of S-scheme heterojunction, the large surface area, and mesoporous structures. The obtained Li2MnO3/CeO2 nanocomposite was highly stable and efficient for the Hg(II) photoreduction runs up to five successive experiments under similar conditions. Moreover, the possible mechanism over heterojunctions Li2MnO3/CeO2 nanocomposites toward the reduction of Hg(II) ions is examined as well. The formation of S-scheme heterojunction photocatalyst provides better photocatalytic applications in terms of air purification, hydrogen production, and water treatment.

Efficient remediation of mercury-contaminated groundwater using MoS2 nanosheets in an in situ reactive zone

Mercury contamination in groundwater is a serious global environmental issue that poses threats to human and environmental health. While MoS2 nanosheets have been proven promising in removing Hg from groundwater, an effective tool for in situ groundwater remediation is still needed. In this study, we investigated the transport and retention behavior of MoS2 nanosheets in sand column, and employed the formed MoS2in situ reactive zone (IRZ) for the remediation of Hg-contaminated groundwater. Breakthrough test revealed that high flow velocity and MoS2 initial concentration promoted the transport of MoS2 in sand column, while the addition of Ca ions increased the retention of MoS2. In Hg removal experiments, the groundwater flow velocity did not influence the Hg removal capacity due to the fast reaction rate between MoS2 and Hg. With an optimized MoS2 loading, MoS2IRZ effectively reduced the Hg effluent concentration down to <1 μg/L without apparent Hg remobilization. Additionally, flake-like MoS2 employed in this study showed much better Hg removal performance than flower-like and bulk MoS2, as well as other reported materials, with the Hg removal capacity a few to tens of times higher than those materials. These results suggest that MoS2 nanosheets have the potential to be an efficient IRZ reactive material for in situ remediation of Hg in contaminated groundwater.

In situ self-activation strategy for the synthesis of double-layered S/Cl co-doped sorbents for elemental mercury removal from oxy-fuel combustion flue gas

Mercury capture from oxy-fuel combustion flue gas remains an enormous challenge for carbon capture and storage because of the lack of cost-effective, sulfur-resistant and water-resistant sorbent. In this work, double-layered S/Cl co-doped sorbents (CDSs) were synthesized through an in situ self-activation method i.e. co-pyrolysis of waste tire and PVC plastic, which were adopted for elemental mercury (Hg0) immobilization from oxy-fuel combustion flue gas. A synergistic effect between waste tire and PVC plastic was observed during co-pyrolysis. For this reason, chlorine was successfully doped into the CDSs in the form of covalent chlorine and ionic chlorine. The CDSs showed high Hg0 removal efficiency (>80 %) over a wide temperature range (20–140 °C) and excellent sulfur and water resistance. Both the initial Hg0 adsorption rate and adsorption capacity of CDSs were far higher compared with raw tire char. The Hg0 removal mechanisms were further proposed, where Hg0 preferentially reacted with covalent chlorine instead of active sulfur species. Density functional theory calculations revealed that the Hg0 adsorption over CDSs was chemisorption with an adsorption energy of −249.85 kJ/mol. The synergistic effect between sulfur and chlorine was beneficial for the formation of HgCl2 whereas it had negligible effect on the formation of HgCl.

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.

Nanocellulose-stabilized nanocomposites for effective Hg(II) removal and detection: a comprehensive review.

Mercury pollution, with India ranked as the world's second-largest emitter, poses a critical environmental and public health challenge and underscores the need for rigorous research and effective mitigation strategies. Nanocellulose is derived from cellulose, the most abundant natural polymer on earth, and stands out as an excellent choice for mercury ion remediation due to its remarkable adsorption capacity, which is attributed to its high specific surface area and abundant functional groups, enabling efficient Hg(II) ion removal from contaminated water sources. This review paper investigates the compelling potential of nanocellulose as a scavenging tool for Hg(II) ion contamination. The comprehensive examination encompasses the fundamental attributes of nanocellulose, its diverse fabrication techniques, and the innovative development methods of nanocellulose-based nanocomposites. The paper further delves into the mechanisms that underlie Hg removal using nanocellulose, as well as the integration of nanocellulose in Hg detection methodologies, and also acknowledges the substantial challenges that lie ahead. This review aims to pave the way for sustainable solutions in mitigating Hg contamination using nanocellulose-based nanocomposites to address the global context of this environmental concern.

Enhanced reductive removal of aqueous Hg(II) by a novel Pd-Cu-BTC catalyst

The reusability of catalytic materials is crucial for their practical applications to environmental water treatment technologies. In this study, we synthesized a novel catalytic metal–organic framework, Pd impregnated Cu-BTC (1,3,5-benzenetricarboxylate), and investigated its performance in the reductive removal of Hg(II). Our analysis of adsorbed Hg species and valence change of metals on the catalyst surface provided valuable insights into the reaction mechanism. Experimental findings revealed that the reactivity and the transformed Hg(0) adsorbed on the catalyst surface were significantly increased following the metal order of Pd > Ru > Pt. Reduced Pd-Cu-BTC exhibited a remarkable Hg(II) removal of 99.9 % within 2.5 min, with the highest adsorption capacity (4.43 mg·g−1) and pseudo-second-order rate constant (k2 = 0.343 g·mg−1·min−1). Increasing the Pd content significantly enhanced Hg(0) adsorption, from 40 % with 1 % Pd to 96 % with 6 % Pd. Moreover, the catalyst maintained its reactivity throughout nine consecutive cycles, effectively removing all aqueous Hg species. The catalyst shows promising potential for recovery through thermal desorption due to the highest adsorbed Hg(0) from Hg(II) reduction reaction. Hence, the reduced Pd-Cu-BTC is an effective and sustainable catalyst for application in the removal of Hg(II) in water and wastewater treatment technologies, highlighting its long-term usability.

High performance and K-poisoning resistance of CuCl2-MnOx/HZSM-5 adsorbent for elemental mercury removal

Manganese-based adsorbents have been extensively researched for the removal of Hg0 from coal-fired flue gas. However, the presence of K2O and K2SO4 in the flue gas significantly diminishes the Hg0 removal performance of the MnOx/HZSM-5 (MH) adsorbent, indicating a lack of tolerance to potassium species. To enhance its K-resistant and further improve the Hg0 removal performance, CuCl2 was applied to modify the MH adsorbent. The optimal CuCl2 loading of 5 wt% (noted as 5CCMH) and Hg0 removal efficiency reach 96.8–100 % between 150 and 250 °C. It was found that CuCl2 modification decreased the surface area, enhanced both reduction ability and surface acidity with two active sites Cu2+ and Cl−, facilitating effective reactions with Hg0 to form HgCl2 and HgO via active chlorine species (Cl*) and chemisorbed oxygen (Oα). Due to the preferential interaction of Cl species with K species, active Cu and Mn species are preserved, enhancing the K2O and K2SO4 resistance of 5CCMH absorbent with high performance for removal Hg0. Additionally, the presence of Cu2+ and Mn4+ contributes abundant acid sites and redox ability, allowing the 5CCMH adsorbents to maintain high Hg0 removal efficiency even after the introduction of K2O and K2SO4. This study provides guidance for designing active adsorbents in power plants using high-alkali-content coal and offers theoretical support for practical applications.

Mechanistic Evidence for Hg Removal from Wastewater by Biologically Produced Sulfur.

A significant quantity of biologically produced sulfur (BPS) is generated as a by-product of chemical and biological desulfurization processes applied to landfill gas treatment. The beneficial upcycling of BPS has seen limited use in the environmental context. The effectiveness and underlying mechanism of BPS as an adsorbent for removing Hg2+ from both solution and wastewater were elucidated based on experiments encompassing surface characterization, adsorption isotherms, kinetics, and thermodynamics. The BPS exhibited remarkable efficacy in removing Hg2+ from solution, with the Langmuir model accurately describing the adsorption process and showing a maximum adsorption capacity of 244 mg g-1. Surface analysis through X-ray photoelectron spectroscopy and scanning electron microscopy revealed that Hg2+ complexed with sulfide on BPS surfaces, forming stable HgS. The adsorbed Hg was strongly retained in BPS, with less than 0.2% of the adsorbed Hg desorbed by strong acids. Adsorption kinetics followed the double-exponential first-order model, showing an initial rapid adsorption phase wherein 75% of the initial Hg2+ was removed within 5 min, followed by a slower adsorption rate. The thermodynamic parameters suggested that adsorption of Hg2+ by BPS was a spontaneous and endothermic process. Additionally, BPS effectively removed Hg2+ from wastewater, showing preference for Hg over other co-existing metals. These findings underscore the potential of BPS as an effective adsorbent for Hg2+ removal from wastewater.

Rational modulation of redox equilibrium over Mn modified Ce-Sn catalyst for low-temperature elimination of NO and Hg0

The synergistic catalytic removal of NO and Hg0 under low temperatures is still a great challenge. Here, we report a Mn-modified Ce-Sn catalyst for simultaneous removal of NO and Hg0 at low temperature. The optimum Mn0.2/Ce0.33Sn0.67 exhibited more than 95 % NO conversion and N2 selectivity above 86 % at 150–250 ℃ as well as Hg0 removal of nearly 100 % within 150–300 ℃. SnO2-promoted Ce-Sn solid solution enhanced the surface proportion of Ce3+, the number of surface chemisorbed oxygen and the electronic interaction within Ce-Sn linkage. Mn modification further reasonably promoted redox cycling at low temperatures and improved acidic distribution of catalyst. Under the cooperation of Ce-Sn and Mn sites, the presence of Hg0 could substantially facilitate the reduction of NO at 250–300 ℃ and the SCR atmosphere had a weak inhibitory effect on Hg0 removal. During the SCR process, the NH4+ and NH2 species that directly reacted with gaseous NO following the Eley − Rideal mechanism and the improved reactivity of NH2 with nitrates following the Langmuir − Hinshelwood mechanism enhanced the NO conversion efficiency at low temperature. Meanwhile, Mn modification could alleviate competitive adsorption of NH3 on Hg0 and promote the formation of more chemically adsorbed mercury species. This work will provide guidance for the design of low-temperature catalysts for the simultaneous removal of NO and Hg0 in flue gas.

Engineering halogen ligand in Fe-based ionic liquid for elemental mercury removal from flue gas

The application of Fe-based ionic liquids (ILs) in elemental mercury (Hg0) removal from flue gas is limited by the low oxidative activity of the Fe(III) center. Here, a strategy of engineering halogen ligand to enhance the oxidative activity of Fe-based ILs for mercury removal was proposed. We developed a series of ionic liquids [Bmim][FeCl4-xBrx] (x = 0–4) with varying ratios of Cl− and Br− ligand substitutions. Mercury removal performance evaluations demonstrated a positive correlation between the oxidative activity towards Hg0 and the number of Br ligand substitutions in the ILs. [Bmim][FeBr4] achieved ∼99 % removal efficiency in the temperature range of 50–150 °C, with a saturated adsorption capacity reaching 205.4 mg/g (at 150 °C). In-situ Raman spectroscopy, DFT calculations, Hg-TPD, and XPS collectively revealed that the introduction of Br significantly lowered the excitation energy of the ligand–metal p-d orbital electron transitions, which facilitates the generation of active bromine species with unfilled 4p orbital, consequently enhancing the oxidative removal performance of Fe-based ILs for Hg0. This work provides an application of metal-based ILs in the realm of mercury removal and broadens the scope of ligand–metal interaction for IL design.

Plackett-Burman and Box-Wilson designs for the removal of mercury (II) by cypress pines and leaves, optimizing the surrounding conditions

In this study, the removal of Hg (II) from cypress leaves and cypress pines was examined. Factors like time of contact (1–60 min), amount of biosorbent used (0.02–0.06 min), pH levels (1.2–6.52 min), initial metal concentration (100–250 ppm) temperature (20–40 min), strength of ions (0.5–1.5 M), and speed of stirring (0–250 min) were studied. Kinetic data were described using both pseudo-first-order and pseudo-second-order models. Equilibrium data were analyzed using Langmuir and Freundlich models, with the Langmuir model fitting the data best. The kinetic data were best described by the pseudo-second-order model. Thermodynamic studies showed that the removal of Hg(II) by cypress leaves was exothermic. The Plackett–Burman design (PBD) and Box–Wilson designs were used for optimization, recommending values of 250 mg/L, 5.98, 7.98 min, and 0.5 g for the variables Co (initial concentration of Hg(II) ions), pH (acidity level), contact time, and mass of KNO3 (potassium nitrate) for the removal of mercury (II) by cypress pines.

Mn-TiO2 catalyst collaborates with trace O3 to enhance the removal of mercury in ESP environment

Ozone, known for its strong oxidizing properties, is commonly utilized in water pollution control. However, the catalytic ozonation of gaseous pollutants also shows potential as an emission reduction technology. The challenge lies in the high concentrations of ozone required in the catalytic process, which increases costs and complexity, hindering widespread adoption. Industrial electrostatic precipitators (ESPs) powered by high-voltage sources can produce ozone during operation, potentially causing environmental pollution if not managed. This study suggests utilizing a catalyst in the low-concentration ozone environment generated by an ESP for the catalytic oxidation of Hg0 in flue gas. The removal efficiency of Hg0 by either the catalyst alone or ozone alone (O3: 10 ppm) is modest at 43 % and 8 % respectively. However, when combined, the catalyst and ozone demonstrate a remarkable removal efficiency of over 98 %, significantly outperforming their individual capabilities. Furthermore, this process exhibits consistent high efficiency in a wide temperature range of 50–150 ℃. The study reveals that in the absence of O3, adsorbed oxygen acts as the primary oxidant, limiting the oxidation of Hg0. The introduction of O3 enhances electron transfer within the Mn-Ti catalyst, optimizing the electronic structure of oxygen and enhancing the oxidizing capacity of lattice oxygen, resulting in superior Hg0 removal efficiency. These findings offer valuable insights for the catalytic ozonation of Hg0.

Experimental and theoretical study on recovered nano amorphous selenium as efficient adsorbents for mercury capture from flue gas

The cost-effective removal of gaseous elemental mercury from coal-fired flue gas is crucial for environmental protection. In this study, nano amorphous selenium (nano-a-Se) adsorbent was recovered from desulfurization wastewater to remove Hg0 in flue gas. The results indicate that nano-a-Se has a high efficiency in the amorphous form with a saturated adsorption capacity of 2034.32 mg g−1. The Se utilization ratio of nano-a-Se reached 80% of the theoretical limit. Meanwhile, nano-a-Se exhibited high resistance to NO and SO2 poisoning. Moreover, the Hg0 removal mechanism of nano-a-Se was analyzed by experimental analysis and density functional theory (DFT) calculations. The results demonstrate that nano-a-Se can convert Hg0 into stable mercury selenide, a high-value by-product with little risk of mercury re-release. Therefore, nano-a-Se is expected to be a novel adsorbent with high efficiency in capturing Hg0, which can help realize the resource utilization of toxic elements from the environment.

Adsorption Behaviors of H2S and CO2 on the Synergistic Removal of HCl and Hg0 in Pyrolytic Waste Plastic Gas on 4Ca-1Co/CA

Adsorption Behaviors of H₂S and CO₂ on the Synergistic Removal of HCl and Hg⁰ in Pyrolytic Waste Plastic Gas on 4Ca-1Co/CA

Comprehensive life cycle assessment of NH2-functionalized magnetic graphene oxide for mercury removal: Carbon emissions and economic evaluation

Heavy metals contamination critically affects human health and ecosystems, necessitating pioneering approaches to diminish their adverse impacts. Hence, this study synthesized aminated magnetic graphene oxide (mGO-NH2) for the removal of mercury (Hg) from aqueous solutions. Although functionalized GO is an emerging technology at the early stages of development, its synthesis and application require special attention to the eco-environmental assessment. Therefore, the life cycle assessment and life cycle cost of mGO-NH2 were investigated from the cradle-to-gate approach for the removal of 1 kg Hg. The adsorption process was optimized based on pH, Hg concentration, adsorbent dose, and contact time at 6.48, 40 mg/l, 150 mg/l, and 35 min, respectively, resulting in an adsorption capacity of 184.17 mg/g. Human carcinogenic toxicity with a 40.42% contribution was the main environmental impact, relating to electricity (35.76%) and ethylenediamine (31.07%) usage. The endpoint method also revealed the pivotal effect of the mGO-NH2 synthesis on human health (90.52%). The most energy demand was supplied by natural gas and crude oil accounting for 70.8% and 22.1%, respectively. A 99.02% CO2 emission originated from fossil fuels consumption based on the greenhouse gas protocol (GGP). The cost of mGO-NH2 was about $143.7/kg with a net present value of $21064.8 per kg Hg removal for a 20-year lifetime. Considering the significant role of material cost (>70%), the utilization of industrial-grade raw materials is recommended to achieve a low-cost adsorbent. This study demonstrated that besides the appropriate performance of mGO-NH2 for Hg removal, it is essential that further studies evaluate eco-friendly approaches to decrease the adverse impacts of this emerging product.

New insight into the intrinsic effect of sulfur dioxide on Hg0 oxidation in the absence/presence of SCR atmosphere

Collaborative control of Hg0 in selective catalytic reduction (SCR) device is considered to be feasible and cost-effective, whereas the negative impact of SO2 remains a thorny issue for industrial applications. Herein, the intrinsic effect mechanism of SO2 on Hg0 oxidation in the absence/presence of SCR atmosphere over the hollow nanotube CoMnTiOx was systematically investigated. It was demonstrated that SO2 possessed a bidirectional effect on Hg0 oxidation, the facilitating effect was attributed to the production of HgSO4 and the inhibiting effect was due to the formation of metal sulfate, which was exactly equilibrated when the deposition of sulfate on the catalyst reached 3.88 %. Interestingly, the presence of SCR atmosphere enhanced the suppression of SO2 on Hg0 oxidation, which was caused by the fact that SO2 + O2 consumed partial Hg0 to form HgSO4, upsetting the reaction equilibrium of HgO reduction induced by SCR atmosphere and ultimately aggravating the reduction process of the already generated HgO. This work provides a new and comprehensive insight into the effect of SO2 on Hg0 oxidation during the synergistic removal of Hg0 in SCR device, which is instructive in exploring strategies to mitigate the SO2 poisoning.

Radiation grafting mediated tailoring of a mercury (Hg(II)) selective adsorbent “RAdMer”: Mechanistic insights, uptake performance and reusability evaluation in artificially contaminated groundwater

The presence of mercury (Hg(II)) in water bodies poses a pressing threat not only to aquatic life forms but also human health. This work proposes the fabrication of a novel thiol (-SH), amine (–NH–) and carboxylic (-COOH) group containing trifunctional adsorbent based on a radiolytically surface engineered biodegradable platform for selective sequestration of Hg(II) from aqueous media. Polyacrylonitrile (PAN) was gamma radiolytically incorporated onto cotton fabric via Radiation Induced Graft Polymerization (RIGP) process, followed by chemical conversion of the nitrile groups using dl-Cysteine as the trifunctional agent. The developed adsorbent RAdMer was characterized by FTIR, TGA, SEM-EDX, EDXRF, XRD, CHNS, 13C NMR and XPS techniques, and tested for Hg(II) removal in batch and continuous flow adsorption modes. Adsorption kinetics and equilibrium characteristics were validated using various theoretical models as well column adsorption models. Density Functional Theory (DFT) calculations performed to determine the complexation mechanism revealed the binding to be occurring predominantly in a 1:2 metal to ligand ratio with calculated binding affinity of −19.63 kcal.mol−1. RAdMer demonstrated fast uptake kinetics with over 60 % of total Hg(II) adsorption occurring within the first 30 min, while peak adsorption capacity was calculated at 174.3 mg.g−1. Moreover, RAdMer could be reused for >5 iterative cycles using an optimized HCl-Thiourea eluent system. Acting upon the UNOs SDG6 principle of providing “clean water and sanitation for all”, RAdMer efficiency was demonstrated with Hg(II) spiked ground water samples to successfully achieve the WHO permissible limit of <1.0 μg.L−1, and can therefore be potentially upscaled as an efficient methodology for remediation of Hg(II) ions in contaminated water.

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.

Rapid coating of polyamide, polyurea, and polythiourea on metal–organic framework surfaces

Well-defined metal–organic framework (MOF)@polymer core–shell composite particles with polyamide, polyurea, and polythiourea as the shell layer have been constructed for the first time using non-solvent-induced surface-aimed polymerization. This surface polymerization method utilizes non-solvent-induced phase separation to concentrate and direct monomers onto MOF particle surfaces, thus completing the coating process in less than 5 min. The generalizability of this method has been demonstrated with different MOFs. Coating MOF particles with any of the three polymers can effectively improve the stability of the MOF in harsh chemical environments. When used for heavy metal removal, polythiourea-coated composite particles (MOF@HDA-PDTC) exhibited a drastically improved Hg(II) removal rate and full utilization of the thione groups for Hg(II) binding compared to their neat polymer counterparts. This highlights the unique benefit of this core–shell architecture for the optimization of diffusion.