Hg Adsorption Capacity Research Articles

Preparation and Adsorption Properties of a Three-Dimensional Superhydrophilic Mercury-Ion-Imprinted Polymer with Dual Recognition Site Based on MoS2/SBA-15.

Water pollution resulting from Hg(II) ions has garnered significant global concern for public health. The flexibility and simplicity of design, cost savings, and ease of operation with adaptive designs provide adsorption with a considerable advantage over other processes. However, MoS2 is hydrophobic in nature, which limits its efficiency in the removal of Hg(II) ions from water. Therefore, the incorporation of hydrophilic SBA-15 as supporting material, combined with a nanoflower-like layered MoS2 and its highly reactive exposed edges, produces hydrophilic properties that effectively eliminate Hg(II) from water . A mercury-ion-imprinted polymer (Hg(II)-IIP) was synthesized on the MoS2/SBA-15 surface using N-allylthiourea (ATU) as a functional monomer to enhance material selectivity and create dual recognition sites. Characterization investigation using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), and water contact angle showed the successful synthesis of Hg(II)-IIP, excellent hydrophilicity, and close interaction between MoS2 and SBA-15. The maximum adsorption capacity of Hg(II)-IIP for Hg(II) under optimized adsorption conditions was 567.78 mg·g-1 in 90 min, which was 6 times greater than that of the IIP solely based only on SBA-15, and followed by pseudo-second-order and aligned more closely fits with the Langmuir adsorption isotherm. Furthermore, the adsorption capacity of the synthesized Hg(II)-IIP was greater than that of three other common monomers IIP. Hg(II)-IIP possesses a strong ability to regenerate, while also showing better selectivity for Hg(II) in the presence of other interfering ions, indicating its robust anti-interference capability in the multivariate mixed solution. The analysis of the actual sample indicated that Hg(II)-IIP attained recoveries between 97.92 and 100.28% in water samples. Theoretical calculations using density functional theory (DFT) and frontier molecular orbital (FMO) indicated that the binding energy of the sulfur atom forming a tetra-ligand with Hg(II) on ATU was 0.6511 eV greater than that of a diligand. The energy gap was determined to be 0.1550 eV, supporting the preference for S-Hg tetra-ligand adsorption.

Plasma-induced aging of microplastics and its effect on mercury transport and transformation

Microplastics are known to adsorb heavy metals, with aged microplastics exhibiting greater adsorption capacity. This study investigates the impact of microplastic aging on the transport and transformation of mercury (Hg), a highly toxic heavy metal. Polystyrene (PS) and polyvinyl chloride (PVC) were aged using plasma treatment to simulate environmental conditions. Characterization of virgin and plasma-treated microplastics revealed aging mechanisms induced by plasma treatment. Notably, aged PS, unlike PVC, did not show a decrease in particle size but exhibited a decrease in specific surface area, likely due to chain cleavage and re-polymerization of polystyrene fragments, and thermal effects during plasma treatment. Both aged PS and PVC demonstrated increased hydrophilicity, enhanced negative charge, and a higher presence of nitrogen- and oxygen-containing functional groups. These changes were correlated with a significant increase in Hg adsorption capacity. Density functional theory (DFT) calculations further indicated that the adsorption of Hg2+ by microplastics is promoted by the presence of oxygen- and nitrogen-containing functional groups. The particularly strong influence of nitrogen-containing functional groups on Hg2+ adsorption was confirmed through both experimental and theoretical approaches. Adsorption kinetics and isothermal experiments, along with X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analyses, were conducted to elucidate the Hg adsorption mechanism of on microplastics before and after aging. The mechanisms involved include pore filling, van der Waals’ forces, electrostatic interactions, hydrophobic interactions, and functional group complexation. The intraparticle diffusion model indicated that adsorption is controlled by multiple steps. Importantly, the surface functional groups of aged microplastics can reduce Hg2+ to Hg+ and adsorb it, suggesting a more complex adsorption process for Hg on aged microplastics. This study provides a scientific basis for understanding microplastic aging and the Hg adsorption mechanism on microplastics, highlighting the complex dynamics of combined microplastic and heavy metal contamination.

Hydrophobic hyper-cross-linked polymer shells encapsulating dispersed nanoscale CuS boosting mercury immobilization

Metal sulfides (MSs) hold significant promise for environmental remediation but are hindered by their low accommodation capacity and poor water resistance. Herein, this work reports a hybrid strategy to address these limitations by assembling highly dispersed CuS nanoparticles within the hyper-cross-linked polymer (HCP). Benefiting from the super-hydrophobicity and well-developed porosity of HCP, alongside the high dispersion and multiple active sites of CuS nanoparticles, the resultant CuS@HCP exhibits exceptional water resistance, enhanced surface area, high mass transfer ability, and substantial Hg0 adsorption capacity. The Hg0 adsorption capacity (Q90) of CuS@HCP3 reaches 1.25 and 1.391 mg/g under N2 and simulated flue gas, respectively. Notably, the normalized Q90 of coated CuS surpasses that of pristine CuS by 25-fold under N2 + 15 % H2O and its durability outstrips most previously reported mineral sulfides even in complex simulated flue gas. Universal research confirms MSs@HCP (M = Zn, Sn, and Fe) equally demonstrate over 15-fold increment in Hg0 retention under high humidity conditions compared to the pristine MSs. Such HCP hybrid strategy universally and effectively optimizes the accommodation capacity and water resistance of MSs, endowing MSs@HCP broad application prospects.

Ketone-based conjugated microporous poly(aniline)s for the ultradeep separation of heavy metal ions

The heavy-metal contamination of aquatic environments presents imminent threat. Herein, we report a class of dual-heteroatomic conjugated microporous poly(aniline)s showing high-affinity separation performance toward heavy metals. The prepared keto-CMPA shows monolayer adsorption capacity for Hg (II) as high as 980 mg g−1 according to the Langmuir model, and ultra-rapid kinetic with h reaching 30.41 mg g−1 that could be described by the pseudo-second-order model. It maintains excellent stability across six reuses under harsh conditions, and furthermore demonstrates ultradeep separation efficiency that could adsorb almost all of heavy metals to ppb level with low usage. For further industrialization, a competent adsorption device was developed to remove heavy metals down to 1 ppb with a remarkable breakthrough over 20,000 BV. Characterizations and DFT calculation showed that the triangular synergistic region formed by the N-O-sites in the singular CMPA structure provided a feasible binding energy to enable the above impressive performance.

Multi-ligand strategy for enhanced removal of heavy metal ions by thiol-functionalized defective Zr-MOFs

Given the significant global concern about heavy metal pollution, the development of effective adsorbents to capture pollutants has become an urgent issue. In this work, thiol-functionalized defective Zr-MSA-DMSA was designed by mixing 2,3-dimercaptosuccinic acid and mercaptosuccinic acid, which was applied for the rapid and efficient removal of M(II) (i.e., Pb(II), Hg(II), Cd(II)) from wastewater. Zr-MSA-DMSA exhibited excellent adsorption performance, and the maximum adsorption capacities for Pb(II), Hg(II), and Cd(II) were 715.2 mg g−1, 862.7 mg g−1, and 450.5 mg g−1. In actual wastewater, Zr-DMSA-MSA exhibited up to 97 % M(II) removal efficiency and excellent anti-interference ability. It also maintained good structural stability after five adsorption/regeneration cycles. Thus, the abundant oxygen vacancies and unsaturated adsorption sites on Zr-MSA-DMSA significantly improved the adsorption performance of M(II). Spectral analysis and DFT calculations confirmed that Zr-MSA-DMSA mainly relied on the coordination of sulfur and oxygen atoms, electrostatic attraction and a large number of defective sites to achieve the adsorption of M(II). Fixed bed experiments showed that Zr-MSA-DMSA exhibited a depletion time of 10500 min and a volume of 7.0 L. In summary, Zr-MSA-DMSA holds significant potential for treating heavy metal wastewater and provides potential applications for defect engineering.

H2S induced in-situ formation of recyclable metal sulfide-based sorbent for elemental mercury sequestration in natural gas

Enlightened by the phenomenon that hydrogen sulfide (H2S) can readily decompose on metal oxides to generate sulfide species and the obtained metal sulfides are generally adopted as Hg-affine ligands for Hg0 capture, a urea modified copper oxide (U-CuO) was prepared via high-temperature calcination of the mixture of urea and copper nitrate for Hg0 removal in natural gas containing H2S. Benefitted from the decomposition of urea and the release of gaseous decomposition products, the as-synthesized U-CuO was enriched with abundant base sites and lattice oxygen, and characterized with developed textural features, which facilitates the diffusion and adsorption of H2S and subsequent sequestration of Hg0. The Hg0 adsorption capacity and uptake rate of U-CuO under simulated natural gas (N2 + 500 ppm H2S+8% H2O) reached as high as 134.06 mg g−1 and 58.32 μg g−1 min−1, respectively, which largely surpassed those of most CuS-based sorbents for Hg0 immobilization. Besides, U-CuO sorbent also exhibited satisfactory recyclability only through simple thermal treatment, the Hg0 removal efficiency of U-CuO maintained above 97 % even after ten adsorption-regeneration rounds. This preparation strategy not only provides valuable hints to guide the design and synthesis of Hg0 sorbents used for natural gas containing H2S but also inspires further investigation for the cost-effective performance enhancement of Hg0 sorbents.

Charge modulation of selenospinel by Mn modification to generate unsaturated Se sites for highly efficient mercury capture

Selenospinel has been regarded as a promising adsorbent for Hg0 capture from the flue gas, and the unsaturated Se1− site is one of the critical factors affecting the Hg0 capture performance. The regulation of selenospinel to generate more unsaturated Se1− sites is a great challenge for the enhanced Hg0 capture performance. Herein, a charge modulation strategy of selenospinel via high-valance Mn modification was proposed to generate the unsaturated Se1− sites for efficient and fast Hg0 capture. The unsaturated Se1− sites showed the high affinity towards Hg0 and decreased the energy barrier of HgSe formation. As a result, Mn modified CuCo2Se4 spinel showed the ultra-high Hg0 adsorption capacity (125.86 mg·g−1) and rate (10.24 mg·g−1∙h−1), which were greatly higher than the previously reported adsorbents. Additionally, Mn modified CuCo2Se4 exhibited the excellent resistance towards SO2 and H2O, making it highly suitable for the practical application. DFT calculation verified the important role of unsaturated Se1− sites derived from Mn modification in the Hg0 removal process. This study developed a metal modification strategy to modulate the charge distribution of selenospinel for Hg0 capture, offering a guidance for adsorbent design in the environmental protection.

Effective elimination of Hg(II) from water bodies with acid-modified magnetic biomass spent coffee grounds: conditional optimization and application.

To maximize the efficiency of biomass waste utilization and waste management, a novel acid-modified magnetic biomass spent coffee grounds (NiFe2O4/SCG) was obtained by pyrolysis at 473K and co-precipitation methods and employed to eliminate bivalent mercury (Hg(II)) in water bodies. The prepared NiFe2O4/SCG adsorbent exhibits remarkable magnetism with a strength of 45.78emu/g and can easily be separated from water via a magnetic force. The adsorption of Hg(II) over the NiFe2O4/SCG has an optimal conditions of pH = 8, T = 39 ℃, and dosage of 0.055 g/L, and the maximal adsorption capacity for Hg(II) is 167.44 mg/g via Response Surface Methodology optimization. The removal of Hg(II) over NiFe2O4/SCG primarily involves ion exchange, electrostatic attraction, and chelation; conforms to the pseudo-second-order kinetic and Langmuir models; and is an endothermic reaction. Additionally, the magnetic biomass NiFe2O4/SCG has good regeneration capability and stability. The application research reveal that inorganic salt ions, nitrogen fertilizer urea, humus, and other contaminants in different actual water bodies (river water, lake water, and the effluent of sewage treatment plant) have little effect on the adsorption of Hg(II) over the NiFe2O4/SCG. The prepared adsorbent NiFe2O4/SCG has practical application value for removing Hg(II) from water bodies.

Preparation of porous lignocellulose biochar adsorbent by cold isostatic pressing pretreatment and study on Hg (II) adsorption properties of C and N dual activity sites

Utilizing corn straw (CS) mainly composed of lignocellulose to prepare physically modified biochar (PCSB) via cold isostatic pressing (CIP) in order to increase the biochar’ s Hg (II) adsorption capacity. The results of the characterization indicated that CIP pretreatment renders PCSB-400′ s structure more porous and higher N content of 16.65 %, leading to more N-containing functional groups partaking in the adsorption process. PCSB-400 adsorbed Hg (II) primarily via C/N synergistic complexation and electrostatic attraction between pores, in addition to the presence of redox reactions of surface functional groups on PCSB-400. The adsorption experiment reveals that PCSB-400 has a high selectivity for the adsorption of Hg (II). The adsorption process of Hg (II) by PCSB-400 more closely resembles the Langmuir model and pseudo-first-order adsorption kinetics equation. The adsorption quantity at saturation is 282.52 mg/g at 25 °C. This paper provided an effective idea to selectively remove Hg (II) in wastewater.

Sustainable Solutions for Heavy Metal Contamination: Characterization and Regeneration of Water Hyacinth Biosorbent in Wastewater Treatment

<p>The water hyacinth biosorbent has undergone thorough characterization and assessment for its capacity to remove heavy metals, specifically Pb(II) and Hg(II), from aqueous solutions. Notably, the biosorbent demonstrated an impressive maximum adsorption capacity for Pb and Hg, reaching values of 158.7 mg/g and 123.5 mg/g, respectively. Indeed, these adsorption capacities align with or even surpass those documented in the existing literature for various biosorbents derived from similar agro-industrial waste materials. Several methods were used to characterize the water hyacinth biosorbent's structure and morphology, including pH-Zero Point Change, scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), and infrared spectrometry with Fourier transform (FT-IR). The water hyacinth biosorbent was found to have broken exteriors with mixed particles that involved useful adsorption clusters such as OH, C=O, and C-O-C. The most effective adsorption of Pb(II) and Hg(II) takes place at a pH of 5.0, using a hyacinth dose of 2 g/L. The chemisorption process is the primary cause of the fast growth rate of the adsorption process, which is governed by pseudo-second-order kinetics. Using a 0.1M HNO3 eluent, both biosorbents were effectively regenerated, enabling effective reuse for up to five cycles. The thermodynamic studies confirm the endothermic nature of the adsorption process.</p>

Elemental mercury removal by copper-containing brominated pyrolytic chars derived from waste printed circuit boards

Waste printed circuit boards (WPCBs) containing brominated flame retardants (BFRs) would result in serious environmental pollution without pertinent treatments. However, bromine-containing materials have been proven highly efficient for elemental mercury removal (Hg0). This work proposes a win–win strategy of a cost-effective Hg0 removal method and a highly efficient utilization of WPCB-derived chars. Diverse copper-containing brominated pyrolytic chars of WPCBs were prepared in a fixed bed reactor at 500–700 °C tailored for Hg0 removal from coal-fired flue gas. The resulting copper-containing pyrolytic chars were proven to have a high Hg0 removal efficiency. Various characterizations and adsorption curves insights into the impacts of copper, sorbent weights, pyrolysis and adsorption temperatures, on Hg0 removal efficiency of WPCB-derived chars. The results indicate that copper in WPCBs enhances the fixation of the bromine elements in pyrolytic chars, resulting in improved Hg0 removal performance. The optimal pyrolysis and adsorption temperatures for pyrolytic chars are 600 °C and 140 °C, respectively. Under optimized conditions, a Hg0 removal efficiency exceeding 90 % is realized after 30 min of adsorption. Notably, the results indicating the Hg0 adsorption capacity of WPCB-derived chars rivals that of commercial activated carbons and significantly surpasses that of biochar. Both adsorption kinetics and characterizations affirm that chemisorption is the predominant adsorption method. The C-Br bond and CuO emerge as crucial active sites facilitating the oxidation of Hg0.

A novel mercapto-functionalized bimetallic Zn/Ni-MOF adsorbents for efficient removal of Hg(II) in wastewater

Heavy metals, especially mercury ions, pose extreme hazards to human health and environmental sustainability. Receiving significant interest lately, metal-organic frameworks with mercapto-functionalization (SH-MOFs) have shown impressive efficacy in effectively eliminating highly hazardous Hg(II) from wastewater. In this investigation, a novel mercapto-functionalized Zn/Ni bimetallic MOF (ZNM-2) was synthesized utilizing a simple solvothermal technique employing zinc and nickel as metal sources and 2-mercaptobenzimidazole (MBI) as the organic ligand. The Hg(II) adsorption capacity by ZNM-2 reached 744.4 mg/g, surpassing that of a single-nickel MOF (NM) 328.8 mg/g. More impressively, ZNM-2 successfully eliminated 99.99 % of Hg(II) from actual water samples, achieving a concentration level for Hg(II) that is lower than the threshold of 1.0 μg/L specified in the GB 5749–2022 drinking water standard. When the pH of Hg(II) solution ranged from 2.0 to 6.0, it exhibited exceptional adsorption capacity and sustained high removal efficiency throughout four consecutive regeneration cycles. The adsorption mechanisms observed in this study were found to conformity with the Langmuir model and PSO kinetic model, suggesting that the predominant mode of Hg(II) adsorption is through a chemisorption process occurring at a monolayer level. The superior Hg(II) removal rate of ZNM-2 can be attributed to the predominant coordination of Hg(II) to the thiol (-SH) groups, as revealed by a combination of FT-IR, XPS analysis, and DFT calculations. Therefore, ZNM-2 is an efficacious Hg(II) absorbent that provides a novel approach to alleviate mercury contamination in wastewater.

Thiophene network polyamides (TPPA) with tri(4-aminophenyl)benzene: Synthesis and removal of Hg2+ from aqueous solution

In this study, the thiophenyl polyamide (TPPA) derived from tri(4-aminophenyl) benzene was synthesized for the removal of Hg2+ from the aqueous solution. The adsorbent was characterized by the Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, scanning electron microscopy, nitrogen adsorption–desorption, thermogravimetric analysis and differential scanning calorimetry. The adsorption capacity of Hg2+ is 518.7 mg g−1 at a dose of 1.1 g/L of adsorbent. TPPA was shown to have the following advantages: (i) the high selectivity for the excess metal ions Hg2+, (ii) the stability in the pH values ranging between 2 and 6, and (iii) the proper recyclability (87 % of Hg2+ can be removed in 5 adsorption–desorption cycles). Our analysis suggests the models of the pseudo-second-order kinetics and the Langmuir isotherm are suitable for the description of the adsorption of Hg2+ on the thiophene network polyamide. Our experimental and theoretical results reveal the relationship between the structures and the adsorption capacities of TPPA, identifying the oxygen atom (amide) and the sulphur atom (thiophene) as the most important chemical-reaction sites.

Simultaneous catalytic oxidation of Hg0 and NO over CoxCuy metal oxides catalyst

In this work, Co3O4, CoxCuy and CuO metal oxides catalysts were synthesized by coprecipitation method and tested in catalytic oxidation of Hg0 and NO. The Co3Cu1 catalyst exhibited nearly 100% Hg0 oxidation efficiency at 100–400 ℃ and 84% NO oxidation efficiency at 250 ℃. Respectively, 1155.2 μg g−1 Hg0 adsorption capacity and 92.9 μmol g−1 NOx adsorption capacity over Co3Cu1 catalyst were measured by Hg0-TPD and NOx-TPD. The largest BET specific surface area of Co3Cu1 catalyst was obtained, reaching 26.2 m2 g−1. And H2-TPR demonstrated that the first reduction peak temperature (192 ℃) of Co3Cu1 catalyst was much lower than that of other catalysts. O2-TPD illustrated that the oxygen storage capacity and oxygen mobility ability of Co3Cu1 catalyst were higher than that of other catalysts. These results were consistent with the results of Hg0 and NO oxidation activity tests. In addition, in-situ DRIFTS spectra of NO adsorption indicated that the band at 1390 cm−1 over Co3Cu1 catalyst disappeared after the pretreatment of Hg0. And the transient experiments of Hg0 adsorption suggested that Hg0 could also be extruded from the surface of Co3Cu1 catalyst after the introduction of NO. It was speculated that there might be competitive adsorption between Hg0 and NO over Co3Cu1 catalyst. Finally, the XPS characterization demonstrated that the Oα and the redox cycle of Co3+ + Cu+ ↔ Co2+ + Cu2+ were involved in Hg0-NO simultaneous oxidation. The Co3Cu1 catalyst was an excellent candidate for Hg0-NO oxidation reaction.

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.

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.

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.

Use of Fe-Mn magnetic adsorbent to remove mercury from wastewater

In this work, Fe-Mn magnetic adsorbent was used to remove mercury from wastewater. This research characterizes the structural properties of the adsorbent and also investigates the effects of the operating conditions to evaluate the adsorbent effectiveness for water treatment applications. In the adsorbent preparation stage, the MnCl2 concentration in the solution was chosen at 0.03 mol/L to synthesize the best adsorbent. The structural properties of the Fe-Mn magnetic adsorbent were examined through SEM, ICP, FTIR, XRD, and VSM analyses. XRD results confirmed the presence of FeMnO4 and Fe3O4. VSM showed the superparamagnetic properties of the adsorbent. The influences of the solution pH, Hg (II) initial concentration, adsorption time, and adsorbent dose were explored. The mercury removal of 99% occurred at 30 min, Hg (II) initial concentration 42 mg/L, pH 6, and adsorbent dose of 4.4 g/L. The pseudo-second order kinetic fitted better to the experimental data. The Langmuir isotherm also suitably corresponded to the data. The maximum Hg (II) adsorption capacity of Fe-Mn magnetic adsorbent was 5.408 mg/g. The positive changes of the Gibbs free energy indicated that the adsorption process was endothermic and spontaneous. Overall, Fe-Mn magnetic adsorbent exhibits commendable performance in removing mercury from wastewater.

Metal-Organic framework derived vulcanized functional materials for ultra-efficient treatment of Hg(Ⅱ) ions in water

Metal-organic frameworks (MOFs) and their derivatives have unparalleled potential in removing heavy metal ions from water. Herein, the synthesis and adsorption performance of porous materials derived from MOF derived (Sulfur@MOF) are described. Sulfur@MOF, which was prepared via a simple vulcanisation method, exhibited increased affinity for Hg(Ⅱ) ions owing to the successful introduction of sulfur. The adsorption capacity of Hg(Ⅱ) ions was studied by measuring the adsorption isotherms, adsorption kinetics and adsorption thermodynamics. Sulfur@MOF exhibited extremely high selectivity for Hg(Ⅱ) ions and could efficiently (99.9 %) capture Hg(Ⅱ) ions with an adsorption capacity of 1.2 g/g (ca. 120 min), reducing reducing pollutants with different concentrations from wastewater to drinking water standards. Moreover, Sulfur@MOF showed good reusability, with the removal rate after six cycles being greater than 95 %. Owing to its ultra-efficient removal ability and high adsorption capacity for Hg(Ⅱ) ions and good recyclability, Sulfur@MOF exhibits good application prospects as an adsorbent for pollutant removal.