Removal Of Hg Research Articles

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.

Decoupling the influence of NOx in flue gas on the application of nano-amorphous selenium for mercury removal

Nitrogen oxides are inevitable hazardous components in coal-fired flue gas. This study designed a series of experiments and combined theoretical calculations to systematically investigate the effect of NOx on the removal of element mercury (Hg0) by nano-amorphous selenium (nano-a-Se). It was found that the impact of NOx on the removal of Hg0 by nano-a-Se primarily involves two mechanisms: competitive adsorption between NOx and Hg0, and the induced reduction effect of NOx on chemisorbed mercury (HgSe). NO inhibits the removal of Hg0 by nano-a-Se, and competitive adsorption is identified as the main influencing factor. Whereas the inhibitory effect of NO2 on the adsorption of Hg0 by nano a-Se can be counteracted due to its oxidizing effect on Hg0. Therefore, although NO2 presents stronger competitiveness than NO in the competitive adsorption with Hg0, it still shows a promoting effect on Hg0 removal, with 50 ppm NO2 restoring 5.7 % of the Hg0 removal efficiency. Additionally, the mechanism of NOx-induced reduction of HgSe was investigated in detail. NO2 is more capable of inducing the reduction of Hg(II) from HgSe to Hg0. This study presents new insights into the underlying influence mechanism, which could provide valuable references for the application of other selenium-based adsorbents.

Enhanced Hg(II) removal by polyethylenimine-modified fly ash-based tobermorite

The polyethylenimine (PEI)-modified fly ash based tobermorite (PTFA) was prepared from fly ash (FA) by hydrothermal synthesis of fly ash-based tobermorite (TFA) and PEI grafting. The TFA and PTFA were systematically characterized, and their Hg(II) removal properties from aqueous solutions were investigated. The influences of pH, adsorbent dosage, contact time, initial concentration, and coexisting ions on removing Hg(II) by PTFA were systematically investigated. The results showed that PTFA had good adsorption capacity and adsorption selectivity towards Hg(II). The optimum dosage of PTFA was 1 g/L, and the preferred pH range was 3 ∼ 5. The adsorption of Hg(II) on PTFA was found to follow the pseudo-second-order and Langmuir model, indicating chemical adsorption and monolayer adsorption between Hg(II) ions and PTFA. The thermodynamic results suggested that the adsorption of Hg(II) on PTFA was spontaneous, heat-absorbing, and entropy-increasing. The maximum adsorption capacity of PTFA for Hg(II) was 43.89 mg/g, which was higher than that of TFA and other reported FA-based adsorbents. The main removal mechanisms involved chemical chelation with oxygen and nitrogen atoms and ion exchange with Ca(II). This study shows that PTFA has good application prospects in treating wastewater containing Hg(II).

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.

Efficient adsorption and desorption of elemental mercury by ordered mesoporous cerium oxide nanoparticles derived from Ce-based metal–organic frameworks

Metal oxide-based adsorbents not only exhibit effective elemental mercury (Hg0) removal capacity but also offer suitability for wet desorption, which is a green treatment method to avoid secondary contamination of deactivated adsorbents. Nevertheless, the limited dispersing capacity of the carrier restricts the loading of active substances, hindering further enhancement of adsorption capacity. The pore structure of adsorbent is also a key factor for wet desorption. In this work, we synthesized a hollow cerium-based metal–organic framework (Ce-mesoMOF) as a sacrificial precursor to obtain ordered mesoporous cerium oxide (OM-CeO₂) via a mesoporous genetic pyrolysis-oxidation mechanism. OM-CeO2 inherits the excellent structural properties of mesoporous MOF with better catalytic activity, exhibiting strong adsorption capacity in various atmospheres (97.6 % in pure N2, 98.8 % in N2 + H2S). Wet desorption of Hg compounds and reduction of the active site can be synergized in Na2S2O3 solution. The octahedral structure with an ordered mesoporous shell greatly facilitates the mass transfer process, as evidenced by the strong adsorption capacity and fast kinetic parameters of OM-CeO2. Density functional theory analysis reveals that the conversion reaction of adsorbed Hg has a low energy barrier on the pyrolytic-oxidized OM-CeO2 and the inhibitory effect of reactive S for Hg0 adsorption transforms into a facilitating effect. This study leverages the structural advantages of ordered mesoporous MOFs in the field of Hg adsorption and imparts reactivity through modification for efficient adsorption–desorption.

Iodide- and electrochemical assisted removal of mercury by Cirsium arvense from gold tailings in the Amansie West District, Ghana

Mercury (Hg) pollution in Ghana through mining has become a serious environmental challenge. This study investigates the potential of Cirsium arvense to photostabilize Hg using electrokinetic current with or without an iodide solution in gold mine tailings heavily contaminated through mining activities in southern Ghana. An initial Hg concentration of 9.60 mg/kg using cold vapor atomic absorption spectrometry (CVAAS) was determined. The biological absorption coefficient, bioconcentration factor, and translocation factor of Hg have been presented. Cirsium arvense therefore had a higher bioconcentration factor (BCF) of 2.6–5.15 mg/kg, and a transfer factor (TF) of 0.24–0.36 indicating a higher efficiency for phytostabilization. Both the rate and time of extractions of Hg from the tailings by Cirsium arvense are efficiently improved in the combined electric current and iodide treatment. Plant and electric current combined treatment and plant and iodide combined treatment had only 60 and 50% phytostabilization rates, respectively. The combined plant, iodide, and electric current treatment has proven to be superior with about >90% Hg removal rate. Therefore, the combined plant, iodide, and electric current treatment resulted in a higher Hg removal efficiency by Cirsium arvense in a shorter period due to higher solubilization rate and electromigration effects on Hg species.

High-performance sulfur-rich COF/PTFE composite membrane for the efficient removal of Hg(II) from acidic wastewater

Covalent organic frameworks (COFs) have emerged as advanced materials for addressing heavy metal pollution in acidic environments. However, powdered COF adsorbents face challenges such as poor operability and a tendency to agglomerate, limiting their industrial wastewater treatment applications. In this study, we prepared a sulfur-rich COF-OSH/mPTFE composite membrane through in situ growth and subsequent modification of COFs on the surface of amino-functionalized PTFE porous membranes. The COF-OSH/mPTFE composite exhibits a remarkable adsorption capacity for mercuric cations (Hg2+), reaching 223.5 mg/g. Notably, even at pH 1, the adsorption capacity remains high at 68.9 mg/g. The adsorption process demonstrates excellent resistance to interference from Na+ and Ca2+ ions and shows good reusability. Furthermore, COF-OSH/mPTFE reduced the concentration of Hg2+ in a 100 mL solution (5 mg/L) by over 80 % within 13 min at pH 5, and by over 40 % at pH 2. Even after continuous treatment of 20 L of Hg2+ solution, a significant reduction in Hg2+ concentration in the filtrate was still observed. The COF-OSH/mPTFE composite membrane addresses the cleanliness and recovery issues associated with powdered adsorbents in adsorption environments. The simple, efficient, and low-energy filtration process endows COF-OSH/mPTFE with excellent capability for treating acidic wastewater containing Hg2+.

Mercury removal from water: insights from MOFs and their composites

Abstract Mercury pollution is disturbing, human health by causing many serious types of diseases. Therefore, elimination of mercury from water bodies is very important that is gaining attention among researchers, and researchers are setting priority measures to make mercury free water. One such measure is the use of MOFs and their composites which are extensively applied for the removal of Hg from water, because of displaying majestical characteristics like high water stability, tunable porosity and surface area as well as easy to synthesize. In this review, we discussed the elimination of Hg ions using MOFs and their composites. We also discussed how MOFs and their composites can be modified that can be more reliable and efficient for removal of pollutants from water particularly mercury ions. Furthermore, we explored the challenges in the application of MOFs and present measures to boost the application range of MOFs. In the same way we also discussed potential of MOFs and their composites to overcome difficulties and research directions for the elimination of Hg (II) ions from water bodies. We expect that this review will offer inclusive and clear understanding to researchers about MOFs and their composite for practical applications to remove mercury from water bodies.

Synthesis of Thiol Functionalized MOF-808 and its Efficiency for Mercury Removal.

A thiol-functionalized MOF-808 was produced and used to remove mercury by post-synthetic modification using 6-mercaponicotinic acid (6mna). Parent MOF-808 was impregnated for varied periods of time in the 6mna solution to create modified MOF-808 materials, known as MOF-808-6mna-x, where x refers to the impregnation time. Diffraction and several spectroscopic techniques were employed to quantify and confirm the coordination of 6mna into MOF-808 framework. The amount of grafted 6man and the ability for adsorption of mercury (Hg) were shown to be linearly associated; the functionalized MOF-808-6mna-36 demonstrated improved Hg(II) removal, with an adsorption capacity of 250 mg/g.

Removal of Hg(II) with MgAl-layered double hydroxide functionalized by schiff base ligands: Application and condition optimization

To effectively remove heavy metal Hg(II) from water bodies, a novel adsorbent of MgAl-layered double hydroxide (LDH) was designed and functionalized with Schiff base. The characterization results of the adsorbent (MgAl-LDH@SiO2-AG) show that the Schiff base polymer was successfully coated onto the outside surface of MgAl-LDH with hexagonal structure. The theoretical maximum adsorption capacity to Hg(II) is 228.46 mg/g at pH 7 and 298 K. The different pH solutions were investigated from pH 2 to 8, and the optimal capacity of MgAl-LDH@SiO2-AG toward Hg(II) achieves 268.7 mg/g at pH = 7.2, T = 36.8 °C, C0 = 32.1 mg/L and dosage = 0.083 g/L. In reality, the adsorbent not only exhibits efficient removal of Hg(II) in various water bodies, including lake water, river water, effluent from sewage treatment plant, but also has an excellent selectivity in electroplating wastewater containing different heavy metal ions. Low contents of TN and TP in real wastewater have less effect on the removal of Hg(II). Moreover, the prepared adsorbent had a good reusability and stability. The reaction mechanism mainly involves chelation with nitrogen/oxygen-containing groups and the predominant participation of nitrogen atoms in the Schiff base functional group. The removal of Hg(II) relies on the pseudo-second-order kinetics and Langmuir model, and is an endothermic and spontaneous chemical reaction. The present work offers a practical method for preparing highly effective adsorptive materials with the LDH composites and for the treatment of heavy metal Hg(II) from water bodies.

Hollow tubular MnOx prepared by flame annealing with cotton fiber as sacrificial template and its applications for Hg0 adsorption in flue gas

The mass discharge of mercury from coal-fired power plant has caused great harm, abating mercury emissions is of preoccupation for protecting public environmental safety and human health. Metal oxides are often used for Hg0 removal in the flue gas. In this paper, a hollow tubular MnOx(MnCot) was successfully prepared by rapid flame annealing using cotton fiber as a sacrificial template. The MnCot were then well characterized and tested for its capability for Hg0 removal in flue gas. The results indicate that the flame assisted synthesis method for rapidly prototyping metal oxides with typical structures is achievable. The hollow tubular structure of the cotton fiber is well reprinted with good crystallization of Mn3O4. The inner diameter of the hollow tubular MnCot is about 10 μm, and the thickness of the tube is about 1 μm. The Hg0 removal efficiency on MnCot can be maintained as high as 90 % under simulated flue gas atmosphere below 240°C. O2 and NO have a positive effect on the Hg0 removal, which can act as the fresh active sits thus enhancing its capability for Hg0 removal. However, the presence of SO2 will result in the surface sulfation on MnCot, thus deteriorating its capability for Hg0 removal. Further, the competitive adsorption between SO2 and Hg0 on the material will also weaken its capability for Hg0 removal. The hollow tubular MnOx rapidly prepared by one-step flame annealing has a good industrial application potential for Hg0 removal in coal-fired flue gas.

Upcycling rice husk ash and coal-fired fly ash as si/al sources into hierarchical ZSM-5 for efficient mercury capture from industrial flue gas

Limiting gaseous Hg0 emission is pressing due to the high toxicity in the ecosystem. Zeolites can be regarded as a promising alternative to carbon-based Hg0 adsorbents. However, the mass transfer limitations of conventional singe-sized zeolites constrain the industrial application of zeolites. This study explores the synthesis of hierarchical ZSM-5 zeolites using rice husk ash (RHA) and coal-fired fly ash (FA) as sustainable sources of silicon and aluminum, aimed at enhancing Hg0 removal from industrial flue gases. By adopting a one-step hydrothermal method, we introduced hierarchical porosity into the ZSM-5 framework, enhancing mass transfer and adsorption efficiencies. Iron (III) chloride (FeCl3) was utilized as an active species for modifying the hierarchical ZSM-5, significantly boosting its Hg0 adsorption capabilities. Fe/6RF-hZ demonstrating more than 92% mercury removal efficiency in 60 min under mixed flue gas condition. The structural and chemical attributes of the synthesized ZSM-5 were detailedly characterized, revealing notable differences in surface chemistry and porosity that correlate with varying calcination temperatures of RHA. TEA analysis reveals that hierarchical ZSM-5 zeolites outperform traditional sorbents in demercuration (DeHg) applications, with exceptional DeHg efficiency, energy efficiency (12 kWh), synthesis cost (860 $/ton), and carbon content (non-carbon). This study not only sheds light on the upcycling of solid wastes in synthesizing novel adsorbents but also contributes to the broader application of zeolitic materials in environmental remediation.

Crystalline Phase Regulates Microbial Methylation Potential of Mercury Bound to MoS2 Nanosheets: Implications for Safe Design of Mercury Removal Materials.

Transition-metal dichalcogenides (TMDs) have shown great promise as selective and high-capacity sorbents for Hg(II) removal from water. Yet, their design should consider safe disposal of spent materials, particularly the subsequent formation of methylmercury (MeHg), a highly potent and bioaccumulative neurotoxin. Here, we show that microbial methylation of mercury bound to MoS2 nanosheets (a representative TMD material) is significant under anoxic conditions commonly encountered in landfills. Notably, the methylation potential is highly dependent on the phase compositions of MoS2. MeHg production was higher for 1T MoS2, as mercury bound to this phase primarily exists as surface complexes that are available for ligand exchange. In comparison, mercury on 2H MoS2 occurs largely in the form of precipitates, particularly monovalent mercury minerals (e.g., Hg2MoO4 and Hg2SO4) that are minimally bioavailable. Thus, even though 1T MoS2 is more effective in Hg(II) removal from aqueous solution due to its higher adsorption affinity and reductive ability, it poses a higher risk of MeHg formation after landfill disposal. These findings highlight the critical role of nanoscale surfaces in enriching heavy metals and subsequently regulating their bioavailability and risks and shed light on the safe design of heavy metal sorbent materials through surface structural modulation.

Enhanced performance of amine and thiol chemically modified graphene oxide for effective removal of Hg(II), Pb(II), and Cr(VI) from aqueous solution

This study describes a novel adsorbent with a multidentate ligand that was facilely fabricated by covalently bonding 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole on graphene oxide (AHMT-PRGO). The AHMT-PRGO nano-adsorbent was used for the effective removal of Hg(II), Pb(II), and Cr(VI) from wastewater. The AHMT-PRGO nano-adsorbent was synthesized by a nucleophilic substitution reaction between GO acyl chloride and AHMT chelating ligand in the presence of tetrabutyl-ammonium bromide as a catalyst. The successful modifications were confirmed via several spectroscopic and electron microscopy instrumentations including UV–Vis, FTIR, Raman, XRD, XPS, SEM, and TEM. The maximum adsorption capacities of Hg(II), Cr(VI), and Pb(II) on the AHMT-PRGO nano-adsorbent were 370.0, 136.2, and 109.6 mg/g, respectively, exceeding those of most previously reported adsorbents. Additionally, the equilibrium contact times for Hg(II), Pb(II), and Cr(VI) were 60, 30, and 400 min, respectively. In a mixture of nine heavy metal ions containing 250 ppm of each ion, the AHMT-PRGO nano-adsorbent exhibited high selectivity for Hg(II) ions. Furthermore, the AHMT-PRGO nano-adsorbent showed high stability over five adsorption–desorption cycles. Additionally, the AHMT-PRGO nano-adsorbent was successfully applied to remove heavy metal ions from real water samples. The novelty of AHMT-PRGO lies in the combination of a multidentate ligand for strong and selective binding with the high surface area and stability offered by covalently bonded graphene oxide. This combination offers potential advantages over traditional adsorbents in terms of adsorption capacity, selectivity, and reusability.

Bifunctional materials based on poly(3-aminocarbazole) for efficient and highly selective detection and adsorption of Hg2+ in water

Herein, two poly(3-aminocarbazole) derivatives containing imidazole N-type acceptor were synthesized and reported, which are named PCPI and PCBI respectively. The fluorescence spectrum shows that PCPI (Em = 498 nm) and PCBI (Em = 398 nm) both have a strong fluorescence emission. It is worth noting that PCPI has a larger stokes shift of 153 nm, which is beneficial for improving the sensitivity of the sensor and enhancing its anti-interference ability. As expected, our experimental results indicate that both PCPI and PCBI can cause a specific response of “fluorescence OFF” to Hg2+ compared with other ions. And PCPI and PCBI both have excellent detection capabilities for Hg2+, with detection limits of 69.8 nM and 11.4 nM respectively. Moreover, PCBI exhibits excellent absorption of Hg2+ with a maximum absorption capacity of 477.8 mg/g at 20 °C. It indicates that PCBI can be used as a functional material for the detection and removal of Hg2+ in water.

Structure-activity relationships, product species distribution and the mechanism of effect of multi-component flue gas on Hg0 adsorption and oxidation over CuO/ACs.

A series of Cu-doped activated cokes (CuO/ACs) were synthesized via an impregnation method and applied for the removal of elemental mercury (Hg0). Structure-activity relationships between Hg0 removal and CuO/AC surface characteristics were identified. Hg0 removal over CuO/AC occurs through a combination of physisorption and chemisorption and is mainly dominated by chemisorption. It was found that 1 nm micropores facilitate Hg0 physisorption. Hg0 could weakly adsorb onto an O-terminated crystal layer, whereas strongly adsorb onto Cu-terminated single highly dispersed, clustered and bulk CuO (110) crystal planes via the Mars-Maessen mechanism. Product distributions and mechanisms of Hg0 adsorption and oxidation over the CuO/AC catalyst under multi-component flue gases are also discussed. O2 enhances both physisorption and chemisorption toward Hg0 by 38%. Inhibition of Hg0 removal by SO2 originates from the competitive adsorption and deactivation of CuO cation vacancies, whereas the impact is weakened by O2 through generating 20% of physically adsorbed mercury product species. NO and O2 promote Hg0 chemisorption efficiency by 93% to form Hg(NO3)2. HOCl and/or Cl2 produced by HCl can oxidize 100% of Hg0 to HgCl2, and the catalytic oxidation efficiency is approximately 29%, but O2 slightly lowers the Hg0 catalytic oxidation efficiency by 8%. The affinity ability between various flue gases and Hg0 follows the order O2 < NO < HCl.

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.

Industrial grade calcium sulfide modified by selenium for elemental mercury removal from flue gas

Metallic sulfides (MS) adsorption is considered as an effective method to remove Hg0 from coal-fire flue gas. Se modification can significantly improve Hg0 removal process on MS due to the high affinity constant between Se and Hg0. CaS as a production from wet flue gas desulfurization has potential Hg0 removal ability. Therefore, in the present work, Se modified industrial grade CaS was prepared to remove Hg0 and the effect of the ratio of CaS to Se on Hg0 removal process was studied. Characterization results show that Ca1-Se1.7 had the richest porous structure and largest surface area resulting in more available surface active sites. In addition, Ca1-Se1.7 has the highest content of Se−, who can remove Hg0 via Hg0(ad)+Se22-→HgSe+Se2-. As a result, Ca1-Se1.7 has the highest Hg0 removal efficiency of nearly 100 % from 60 ℃ to 100 ℃, and it reaches 85 % even in the presence of 500 ppm SO2. The Hg0 adsorption kinetic was well defined by the pseudo-first-order kinetic model and internal diffusion model, so that Hg0 diffusion especially internal diffusion is the primary controlling step.

Karakterisasi Performa Adsorben Cangkang Telur Pada Proses Penyerapan Logam Merkuri (Hg)

Mercury (Hg) is a highly toxic heavy metal with no biological benefits, posing significant environmental and health risks upon exposure. This study investigates the adsorption characteristics of chicken eggshell-derived adsorbents for the removal of Hg from aqueous solutions. The adsorbent preparation involved washing, drying, calcination, and KOH activation. Results indicated that the 170-mesh size adsorbent exhibited the highest adsorption efficiency, achieving a 99.70% removal rate of Hg. adsorption capacity tests revealed values ranging from 79,90 to 88,90 mg/g, conforming to the Indonesian National Standard (SNI) for activated carbon. Functional group analysis using Fourier-Transform Infrared Spectroscopy (FT-IR) identified a significant increase in aldehyde and ketone groups post-activation. The adsorption process reached equilibrium within 90 minutes, with optimal removal efficiency observed at an initial Hg concentration of 3,0 mg/L. These findings suggest that chicken eggshell-based adsorbents are a cost-effective and efficient solution for mitigating Hg contamination in wastewater, offering a sustainable alternative to conventional methods.

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.