Removal Of Mercury Ions Research Articles

Hydrothermally synthesis of a green SnS-Carbon microplate adsorbent for the removal of mercury ion from water samples

Mercury ion (Hg2+) finds a broad industrial application and due to its significant toxicity to both humans and aquatic life, development of highly effective adsorbents for its removal holds considerable importance. This study introduces a green adsorbent consisting of tin sulfide (SnS)‑carbon microplates synthesized through a straightforward one-step hydrothermal process followed by its application for the removal of Hg2+ from water samples. The synthesized adsorbent is characterized using Fourier Transform Infrared Spectrophotometry (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive X-ray spectroscopy (EDX), Thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) and X-Ray diffraction analysis (XRD). Through the optimization of crucial parameters and with thanks to the effective interaction between S atoms (soft base) of SnS-C adsorbent and Hg2+ (soft acid), an impressive Hg2+ removal percentage of approximately 99.0 % is achieved for 100 mg L−1 Hg2+. Interpreting of isotherm models indicate that Hg2+ adsorption conforms to the Langmuir isotherm with a maximum adsorption capacity of 238.1 mg/g. Finally, the SnS-Carbon microplate adsorbent exhibits notable advantages, including a green and convenient synthesis route (achieved through a one-step hydrothermal method) and high efficiency, making it a potent adsorbent for the decontamination of Hg2+ from water samples.

Use of Activated and Modified Pumice Stone for Removal of Mercury (II) and Arsenic (III) Ions From Aqueous Solution

Removal of Hg (II) and As (III) ions from aqueous solutions using activated and modified pumice stone were investigated. The pH, temperature, initial metal ion concentration which are very important for removal studies, were investigated by batch method. The experiments demonstrated that the equilibrium adsorption data fit the Freundlich isotherm model well for Hg (II) and As (III) ions. The negative value of ΔH° = -199.92 kJ mol-1 and -78,15 kJ mol-1 for mercury (II) and arsenic (III) ions indicates that the adsorption process is exothermic. ΔS° were calculated as -267.85 J K-1 mol-1 for As (III) ions and the positive value of ΔS° = 0.69 kJ K-1 mol-1 for Hg (II) ions. The negative value of ΔG°=-405.14 kJ mol-1 for Hg (II) ions and -1.67 kJ mol-1 for As (III) ions indicates that adsorption is voluntary. EDTA has been found to be a good desorbent in desorption studies to recover arsenic and Hg ions. The experiments show that pumice stone can be used for Hg (II) and As (III) removal in aqueous solution.

Efficient Removal of Mercury from Wastewater Solutions by a Nitrogen-Doped Hyper-Crosslinked Polyamine.

Mercury, a highly toxic metal and pollutant, poses a significant risk to human health and the environment. This study describes the synthesis of a new nitrogen-doped heteroaromatic hyper-crosslinked polyamine (HCPA) via the polycondensation of 2,6-diaminopyrazine and tris(4-formylphenyl)amine for the efficient removal of mercury ions from aqueous solutions. The HCPA polymer was characterized by solid-state 13C-NMR and FT-IR spectroscopy. A powder X-ray diffraction and thermogravimetric analysis showed that the polymer was semicrystalline in nature and stable up to 500 °C. Adsorption isotherms indicated that mercury adsorption occurred via mono- and multilayer adsorption by HCPA, as depicted by the Langmuir, Freundlich, and Redlich-Peterson isotherm models, with a maximum adsorption capacity of qm = 333.3 mg/g. Adsorption kinetic models suggested that the adsorption process was fast and effective, reaching equilibrium within 20 min. Thermodynamics of the adsorption process revealed that it was endothermic and spontaneous in nature due to the positive ΔH0 of 48 kJ/mol and negative ΔG0 values of -4.5 kJ/mol at 293 K. Wastewater treatment revealed 98% removal of mercury indicating the selective nature of HCPA. Finally, HCPA exhibited excellent performance and regeneration up to three cycles, demonstrating its great potential as an adsorbent for environmental remediation applications.

Mercury Ion Selective Adsorption from Aqueous Solution Using Amino-Functionalized Magnetic Fe2O3/SiO2 Nanocomposite.

This study focuses on the development of new amino-functionalized magnetic Fe2O3/SiO2 nanocomposites with varying silicate shell ratios (1:0.5, 1:1, and 1:2) for the efficient elimination of Hg2+ ions found in solutions. The Fe2O3/SiO2-NH2 adsorbents were characterized for their structural, surface, and magnetic properties using various techniques, including Fourier transform infrared spectrum (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Braunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA), zeta-potential, and particle size measurement. We investigated the adsorption circumstances, such as pH, dosage of the adsorbent, and duration of adsorption. The pH value that yielded the best results was determined to be 5.0. The Fe2O3/SiO2-NH2 adsorbent with a silicate ratio of (1:2) exhibited the largest amount of adsorption capacity of 152.03 mg g-1. This can be attributed to its significantly large specific surface area of 100.1 m2 g-1, which surpasses that of other adsorbents. The adsorbent with amino functionalization demonstrated a strong affinity for Hg2+ ions due to the chemical interactions between the metal ions and the amino groups on the surface. The analysis of adsorption kinetics demonstrated that the adsorption outcomes adhere to the pseudo-second-order kinetic model. The study of adsorption isotherms revealed that the adsorption followed the Langmuir model, indicating that the adsorption of Hg2+ ions with the adsorbent occurred as a monomolecular layer adsorption process. Furthermore, the thermodynamic analyses revealed that the adsorption of Hg2+ ions using the adsorbent was characterized by a spontaneous and endothermic process. Additionally, the adsorbent has the ability to selectively extract mercury ions from a complex mixture of ions. The Fe2O3/SiO2-NH2 nanocomposite, which is loaded with metal, can be easily recovered from a water solution due to its magnetic properties. Moreover, it can be regenerated effortlessly through acid treatment. This study highlights the potential use of amino-functionalized Fe2O3/SiO2 magnetic nanoparticles as a highly efficient, reusable adsorbent for the removal of mercury ions from contaminated wastewater.

Optimization and Characterization of a New Environmentally Friendly Adsorbent to Remove Mercury Ions from Aqueous Solutions

Optimization and Characterization of a New Environmentally Friendly Adsorbent to Remove Mercury Ions from Aqueous Solutions

Evaluating the Potential of Modified Mango Leaves as a Biosorbent for the Removal of Mercury (II) Ion and Congo Red from Wastewater

The discharge of harmful metallic elements from industrial byproducts has resulted in notable environmental and public health risks. The aim of this study was to investigate the effectiveness of mango leaves as a cost-effective adsorbent in eliminating Hg (II) ions from industrial effluents. Experimental procedures were carried out under controlled conditions at ambient temperature to evaluate the influence of pH, contact duration, initial metal levels, adsorbent quantity, and temperature on the adsorption mechanism. The most favorable pH for optimal Hg (II) ions adsorption was identified at pH 7. The adsorption process displayed swift kinetics in the initial 30 minutes of contact, leading to a removal rate exceeding 90%, with equilibrium achieved after 70 minutes of stirring. Analysis of kinetics revealed a significant correlation coefficient for a pseudo-second-order kinetic equation. The absorption of Hg (II) ions escalated with increased stirring intensity and decreased adsorbent amount. The interaction between Hg (II) ions, Congo red, and mango leaves was analyzed employing Langmuir, Freundlich, and BET isotherm models. The equilibrium data was best fitted by the Langmuir model, presenting a correlation coefficient of 0.98 and a maximum adsorption capacity of 28.40 mg/g. These results underscore the potential of mango leaves as an affordable bio adsorbent for addressing heavy metal pollution in wastewater.

ZIF-7-NH2 functionalized collagen fibers for effective and selective mercury ion capture

Adsorptive removal of mercury ion from wastewater has become a hot topic due to the toxicity and persistence; acquiring adsorbent materials with high-capacity, rapid-kinetic, super-selective while low-cost features are highly demanded. Herein, based on the full functionality of collagen fiber (CF) from the leather waste, we proposed an innovative synthetic approach through exploiting amino-functionalized ZIF-7 (ZIF-7-NH2) as functional groups to facilely in-situ incorporate with CF, affording low-cost but effective adsorbent materials of CF/ZIF-7-NH2 composite maximizing both functions of CF and ZIF-7-NH2 in the Hg(II) capture. Remarkably, it exhibits an ultra-high capacity as high as 909.09 mg g-1, fast kinetics that could remove 99.01 % of 200 mg·L-1 within 20 min, and significant selectivity of SHg/M (KdHg/KdM) as large as 522–1017 over Mg2+, K+, Ca2+, Cd2+, and Mn2+. We understand such an impressive adsorption is contributed by the synergistic action between functional groups including on the CF and ZIF-7-NH2. This study offers an effective method for removing heavy metal ions, achieving efficient removal of Hg(II) ions for pollution control, and promoting the reuse of waste CF to reduce waste accumulation in various aspects.

Modelling and optimising the performance of graphene oxide-Cu2SnS3-polyaniline nanocomposite as an adsorbent for mercury ion removal.

Finding a cost-effective, efficient, and environmentally friendly technique for the removal of mercury ion (Hg2+) in water and wastewater can be a challenging task. This paper presents a novel and efficient adsorbent known as the graphene oxide-Cu2SnS3-polyaniline (GO-CTS-PANI) nanocomposite, which was synthesised and utilised to eliminate Hg2+ from water samples. The soft-soft interaction between Hg2+ and sulphur atoms besides chelating interaction between -N and Hg2+ is the main mechanism for Hg2+ adsorption onto the GO-CTS-PANI adsorbent. Various characterisation techniques, including Fourier transform infrared spectrophotometry (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), elemental mapping analysis, and X-ray diffraction analysis (XRD), were employed to analyse the adsorbent. The Box-Behnken method, utilising Design Expert Version 7.0.0, was employed to optimise the crucial factors influencing the adsorption process, such as pH, adsorbent quantity, and contact time. The results indicated that the most efficient adsorption occurred at pH 6.5, with 12mg of GO-CTS-PANI adsorbent, and 30-min contact time that results in a maximum removal rate of 95% for 50mg/L Hg2+ ions. The study also investigated the isotherm and kinetics of the adsorption process that the adsorption of Hg2+ onto the adsorbent happened in sequential layers (Freundlich isotherm) and followed by the pseudo-second-order kinetic model. Furthermore, response surface methodology (RSM) analysis indicates that pH is the most influential parameter in enhancing adsorption efficiency. In addition to traditional models, this study employed some artificial intelligence (AI) methods including the Random Forest algorithm to enhance the prediction of adsorption process efficiency. The findings demonstrated that the Random Forest algorithm exhibited high accuracy with a correlation coefficient of 0.98 between actual and predicted adsorption rates. This study highlights the potential of the GO-CTS-PANI nanocomposite for effectively removing of Hg2+ ions from water resources.

Preparation of dopamine/L-cysteine modified PVDF composite membrane and its application in the removal of mercury ions from water

Polyvinylidene fluoride (PVDF), embodying a stabilization under thermal environment and capability to resist chemical corrosion, is widely used as a membrane-forming material. However, its inherent hydrophobicity and lack of active functional groups in the structure limit its suitability for adsorption applications. In this study, PVDF-based membranes were first prepared by the non-solvent phase inversion method, and then, polydopamine (PDA) was coated on these membranes by the oxidative self-polymerization of dopamine (DA). Then, L-cysteine (LCys) was grafted by self-assembly to obtain a highly hydrophilic PVDF composite (PVDF@PDA-LCys) membrane with excellent ability for Hg(II) ion capture. The membrane has the following characteristics: excellent hydrophilicity, with a water contact angle (WCA) that drops to 0° within 3 s, which is far superior to the 89.22° WCA of the PVDF-based membrane. Given an 10 mg·L−1 initial concentration of Hg(II), adsorption experiences 120 min, the removal efficiency reaches 95.14%. The fitted maximum adsorption capacity is 97.98 mg·g−1. Additionally, the composite membrane exhibits good acid resistance. When the solution pH is as low as 1.5, the Hg(II) ion removal efficiency is still close to 70%. The performance of the composite membrane remains stable after repeated use. This study demonstrates an environmentally friendly and practical method for preparing PVDF-based composite membranes with potential applications in wastewater treatment.

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.

Post-synthetic modification on metal organic frameworks composite for efficient removal and sensitive detection of mercury ions in water

Post-synthetic modification (PSM) technique is employed on the optimization of metal organic frameworks (MOFs) composites. In this work, a new Zr-MOF derived from UiO-66 is prepared and used as efficient adsorbents for mercury removal from water and able to detect mercury ions with excellent selectivity. It is observed that the fluorescence intensity of UiO-66-An exhibits good linearity across the concentration range of 0.5–2.5 μM and the detection limit of mercury is calculated to be as low as 2.67 × 10-8 M which is below the effluent standard declared by WHO. Furthermore, the removal efficiency of UiO-66-An for Hg (II) can still maintain 64.8 % after 5 cycles of adsorption–desorption process. In addition, the adsorption capacity of the adsorbent is determined to be as high as 303.03 mg/g for mercury, indicating the successful integration of adsorptive and detective functions together on a single adsorbent material which is beneficial for practical application in mercury management.

Anchoring thiol-rich traps in 1D channel wall of metal-organic framework for efficient removal of mercury ions

Anchoring thiol-rich traps in 1D channel wall of metal-organic framework for efficient removal of mercury ions

Designing and evaluation of thiosemicarbazide-functionalized/ion-imprinted cellulose for selective removal of mercury (II) ion

For aquatic ecosystems, Hg2+ removal from wastewater is crucial. However, getting high-efficiency Hg2+ extraction is still a challenge due to slow rates and poor selectivity. The active thiosemicarbazide (TSC) chelating units were added to the cellulose (CE) in this work using a novel synthetic pathway. The TSC-CE derivative was then used to produce a Hg2+ ion-imprinted sorbent. Initially, the Michael reaction was used to yield cyanoethyl cellulose (CEC). TSC units were combined by a chemical reaction with the added -CN groups. After Hg2+ was attached to TSC-CE, it was cross-linked with glutaraldehyde before being eliminated via elution with HNO3/EDTA. The Hg2+ imprinted sorbent (Hg-TSC-CE) achieved improved adsorption selectivity for Hg2+ and significantly higher adsorption capacity (qm = 353 ± 0.5 mg/g) in comparison to the non-imprinted sorbent. The FTIR and XPS studies both gave strong evidence supporting the kinetic results for the pseudo-second-order model, which said that coordination is the main process of adsorption. The Langmuir model also well explained the isotherms. It showed that Hg2+ mainly adsorption took place in monolayers, with a pHZPC value of about 5.6. Moreover, the Hg2+ adsorption was endothermic, and the optimum pH was observed at 5.

Highly selective detection and removal of mercury ions in the aquatic environment based on magnetic ZIF-71 multifunctional composites with sufficient chlorine functional groups

The development of both detection and removal technologies for heavy metal ions is of great importance. Most of the existing adsorbents that contain oxygen, nitrogen or sulfur functional groups can remove heavy metals, but achieving both selective detection and removal of a single metal ion is difficult because they bind to a wide range of heavy metal ions. Herein, we selected zeolite imidazolium hydrochloride framework-71 (ZIF-71) with sufficient chlorine functional groups to fabricate magnetic ZIF-71 multifunctional composites (M-ZIF-71). M-ZIF-71 had a large specific surface area, excellent water stability, and good magnetic properties, which made M-ZIF-71 conducive to the separation and recovery of adsorbents and the assembly of electrodes. M-ZIF-71 exhibited high selectivity, wide linear range (1–500 μg/L), and low detection limit (0.32 μg/L) for electrochemical detection of mercury ions (Hg2+). Meanwhile, M-ZIF-71 demonstrated rapid Hg2+ adsorption with a high capacity of 571.2 mg/g and excellent recyclability. The high selectivity for Hg2+ was attributed to the powerful affinity of highly electronegative chlorine and Hg2+. Moreover, XPS spectra demonstrated the interaction between chlorine and Hg2+. This work provides a new inspiration for applications in the targeted monitoring and removal of heavy metal pollution.

Dual-Responsive Hydrogels for Mercury Ion Detection and Removal from Wastewater.

This study describes the development of a fast and cost-effective method for the detection and removal of Hg2+ ions from aqueous media, consisting of hydrogels incorporating chelating agents and a rhodamine derivative (to afford a qualitative evaluation of the heavy metal entrapment inside the 3D polymeric matrix). These hydrogels, designed for the simultaneous detection and entrapment of mercury, were obtained through the photopolymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) and N-vinyl-2-pyrrolidone (NVP), utilizing N,N'-methylenebisacrylamide (MBA) as crosslinker, in the presence of polyvinyl alcohol (PVA), a rhodamine B derivative, and one of the following chelating agents: phytic acid, 1,3-diamino-2-hydroxypropane-tetraacetic acid, triethylenetetramine-hexaacetic acid, or ethylenediaminetetraacetic acid disodium salt. The rhodamine derivative had a dual purpose in this study: firstly, it was incorporated into the hydrogel to allow the qualitative evaluation of mercury entrapment through its fluorogenic switch-off abilities when sensing Hg2+ ions; secondly, it was used to quantitatively evaluate the level of residual mercury from the decontaminated aqueous solutions, via the UV-Vis technique. The ICP-MS analysis of the hydrogels also confirmed the successful entrapment of mercury inside the hydrogels and a good correlation with the UV-Vis method.

Heavy metal decontamination by ion exchange polymers for water purification: counterintuitive cation removal by an anion exchange polymer

Ion exchange polymers were used for mercury and lead ions removal in water. The heavy metal ion concentration was analyzed by two independent methods: inductively coupled plasma–optical emission spectroscopy (ICP-OES) and gravimetry. The studied cation exchange polymer (CEP) was sulfonated poly(ether ether ketone) (SPEEK), and the anion exchange polymer (AEP) was poly(sulfone trimethylammonium) chloride (PSU-TMA). The removal capacity was connected with the ion exchange capacity (IEC) equal to 1.6 meq/g for both polymers. The concentration ranges were 0.15–0.006 mM for Hg2+ and 10.8–1.0 mM for Pb2+. SPEEK achieved 100% removal efficiency for mercury and lead if the concentration was below the maximum sorption capacity (Qmax), which was about 210 mg/g for Pb2+ with SPEEK. For PSU-TMA, the surprising removal efficiency of 100% for Hg2+, which seemed incompatible with ion exchange, was related to the formation of very stable complex anions that can be sorbed by an AEP. Langmuir adsorption theory was applied for the thermodynamic description of lead removal by SPEEK. A second-order law was effective to describe the kinetics of the process.

A green route to the synthesis of highly porous activated carbon from walnut shells for mercury removal

Activated carbon with a high surface area was synthesized using walnut shells with the objective of removing mercury ions. The procedure involved the utilization of potassium carbonate as the chemical activator. The porous material obtained was subjected to characterization using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) analysis, and X-ray photoelectron spectroscopy (XPS). The BET surface areas obtained in this study reach up to 1046.9 m2/g, whereas the pore volumes range up to 0.665 cm3/g. Additionally, the findings indicate that the utilization of K2CO3 for chemical activation leads to the formation of a mostly amorphous structure. The present study aimed to evaluate the impact of several factors including mass dosage, pH, initial concentration of mercury, temperature, and contact time, on the efficiency of mercury removal. It was observed that the adsorption process exhibited spontaneity, endothermicity, and an increase in entropy. At a temperature of 35 °C, the adsorbent had a maximum adsorption capacity of 182.9 mg/g. The mechanism of adsorption involves the participation of ion exchange and electrostatic attractions, which combine synergistically to facilitate the process. This highlights the significance of both chemical and physical adsorption in the overall phenomenon.

Rational construction of MoSx via defect engineering for efficient removal of mercury ions from aqueous solution

Mercury ions (Hg2+) are one of the most physiologically toxic heavy metal ions in water. Developing adsorbents for separating and removing mercury ions from aquatic systems has important environmental and social significance. Owing to the hard-soft-acid-base interaction between mercury and sulfur (S) atoms, two-dimensional layered MoS2 holds great promise in capture physiologically toxic Hg2+ from water, but most S atoms are located inside the bulk MoS2, hindering the effective contact with mercury. Defects engineering is considered as an effective way to adjust the structure and achieve superior performance of MoS2. However, reasonable and fine defect modulation to enhance the mercury adsorption performance remains a challenging task. Herein, we reported that molybdenum sulfide with Mo-vacancy structure (MV-MoSx) was fabricated via hydrothermal method and employed to uptake Hg2+. The results showed that this defect type significantly increased the concentration of Mo stripping defects, exposed more active S atoms, and provided MoSx with excellent adsorption performance in adsorption capacity, adsorption kinetics, distribution coefficient, selectivity and so on. In particular, MV-MoSx demonstrates a substantial actual adsorption capacity for mercury, reaching as high as 3723.3 mg/g, which is in close proximity to its theoretical adsorption capacity of 3945.95 mg/g. More importantly, a functionalized composite aerogel system based on MV-MoSx was constructed, which successfully reduced the concentration of Hg2+ solution below the concentration permitted by drinking water standards. Our study not only provide a theoretical basis for the design of novel defect engineering, but also expand the application of transition metal sulfides in the enrichment and separation of heavy metal ions.

Role of EDTA protonation in chelation-based removal of mercury ions from water.

A robust method of hazardous metal ion removal from an aqueous environment involves the use of chelating agents, such as ethylenediaminetetraacetic acid (EDTA). Here, we focus on mercury (Hg2+) uptake by EDTA using both molecular dynamics and density functional theory simulations. Our results indicate that the deprotonation of the EDTA carboxylate groups improves the localization of negative charge on the deprotonated sites. This mechanism facilitates charge transfer between the metal ions and EDTA, and provides a stronger and more stable EDTA-Hg2+ complex formation improving the efficiency of the chelation process. The best metal removal conditions are achieved using the fully deprotonated form of EDTA, which naturally occurs at pH levels above 3.

Synthesis of dithioglycol-functionalized periodic mesoporous organosilicas for the simultaneous removal of mercury ions and organic dyes from water

Synthesis of PMOs containing thiol and thioether groups for simultaneous removal of Hg(ii) and RhB from simulated sewage is reported.