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Sulfur-doped biochar (S4BC) was prepared with cherry kernel powder as carbon source, Na2S2O3 as sulfur source and chemical activator. Na2S2O3 can activate biochar through the reaction with carbon, intercalation of alkali metals and the generated gas rushing out of pores, and at the same time, active sulfur atoms are doped into biochar during pyrolysis. The physical and chemical properties of S4BC adsorbent were evaluated by various characterization techniques. The results show that S4BC calcined at 800 °C has huge specific surface area of 959.6 m2/g, developed pore structure, and high content of S (18.84 wt%). Moreover, due to the existence of sulfur and oxygen functional groups, S4BC-800 provides sufficient active sites for the adsorption of Hg2+. According to Langmuir model, the maximum adsorption capacity of S4BC-800 for Hg2+ is 724 mg/g at 313 K, and the adsorption speed is fast with excellent stability and reusability. The microfiltration membrane device based on S4BC-800 can effectively remove the low concentration of Hg2+ in the solution. In this study, a simple method for preparing SBC materials is developed, which is not only of great significance as an adsorbent for Hg2+, but also provides a new choice for the preparation of heteroatom-doped materials.

The mercury adsorption properties of carbon-based materials prepared from jacaranda (Jacaranda mimosifolia) and guava (Psidium guajava) seed wastes are reported and compared in this paper. These adsorbent samples were obtained via pyrolysis and hydrothermal carbonization. Mercury adsorption equilibrium was studied at pH 4 and 20–40 °C, and the adsorption enthalpy changes were calculated for all adsorbent samples. The results showed that jacaranda-based materials contained a higher amount of acidic functional groups than guava seed-based adsorbents, and consequently, their mercury adsorption properties were better. The surface area of these adsorbents was

Adsorbents modified solely with chlorine have limited effectiveness in removing mercury at high temperatures. This study aims to investigate the influence of various acid (HNO3, H2SO4, and H2O2) loadings on the removal efficiency of mercury from NH4Cl-modified adsorbents. The objective is to develop rice straw carbon adsorbents that are both more efficient and cost-effective. The experiments were conducted on a fixed bed experimental platform, with SEM and BET to observe the physical property changes of the modified char samples. XPS analysis was employed to analyze the effects of oxygen, chlorine, and sulfur functional groups. Additionally, a kinetic model was used to investigate the interaction mechanism between the adsorbent and mercury. The findings demonstrate that co-modification surpasses the use of NH4Cl alone, with the combination of NH4Cl and HNO3 yielding the best resu lts. Co-modification enhances the development of a more refined and compact pore structure on the char surface, promoting the physical adsorption of mercury. Moreover, an increased presence of chlorine and oxygen functional groups is observed on the char surface, particularly in the NH4Cl and HNO3 co-modified samples, further enhancing the chemical adsorption capacity of the char. The results from the kinetic analysis support this conclusion. Furthermore, the adsorption process of Hg0 relies on both external mass transfer and chemical adsorption, with the chemical adsorption process playing a more significant role as the controlling factor. [ABSTRACT FROM AUTHOR]

Herein, a new type of super active nitrogen-doped biochar sheet (SNBC) was prepared by two-step pyrolysis and KOH chemical activation with melamine and cherry kernel powder as precursors of nitrogen and carbon source for removing Hg2+ from wastewater. The N2 adsorption/desorption and scanning electron microscope characterization revealed that the resulted SNBC under 600 °C calcination owned huge specific surface area of 2828 m2/g and plenty of well-developed micropores, and X-ray photoelectron spectroscopy and Fourier transform-infrared spectroscopy analysis testified the existence of functional groups containing N and O, which could provide adsorption sites for Hg2+. The SNBC-600 showed high adsorption capacity for Hg2+ even at low pH, and interfering cations had little effect on the adsorption. The adsorption process was rapid and dynamic data fit the pseudo-second-order dynamic model well. The maximum adsorption capacity of Hg2+ on SNBC-600 calculated by Langmuir model was 230 mg/g. After six times of reuse, the adsorption capacity still exceeded 200 mg/g, exhibiting good reusability. The designed microfiltration membrane device base on SNBC-600 could remove low concentration of Hg2+ effectively from solution. This study provided a simple and environment-friendly method for manufacturing nitrogen-doped biochar sheet, which was of great significance in the practical application of Hg2+ pollution treatment. [ABSTRACT FROM AUTHOR]

A mesoporous silica adsorbent modified with 1,2-ethane dithiol was conveniently prepared by co-condensation and further surface grafting method. To achieve this synthesis, trimethoxyvinylsilane (TMVS, 20 mol%) was introduced into the silica wall framework along with tetraethoxysilane (TEOS) in the initial reaction mixture during the sol–gel condensation process. Next, to modify the dithiol groups onto the mesoporous silica adsorbent surfaces, the incorporated vinyl groups into the mesopore walls were reacted with 1,2-ethane dithiol via click reaction. The prepared dithiol-modified silica adsorbent (DTMSA) material was characterized by a range of instruments including XRD, FT-IR, N2 sorption, and so on. The DTMSA material showed selective adsorption of mercury ions with high adsorption quantity of 252 mg/g and a removal capacity of nearly ~ 90% from the initial metal ion mixture containing other competitive metals (Zn2+, Ni2+, Pb2+, Cd2+, and Fe2+) ions. The DTMSA adsorbent showed recyclable properties up to five cycles while treating with an acidic aqueous solution (0.1 M HCl), and therefore the DTMSA adsorbent can be recycled and reused up to five times without altering the adsorption efficiency. The experimental results demonstrated that the DTMSA adsorbent might be used for selective adsorption of harmful Hg2+ ions from an aqueous solution. [ABSTRACT FROM AUTHOR]

Waste water contaminated with inorganic mercury is considered a serious environmental problem, mainly due to the hazardous effects this contaminant causes on human health. Thus, the present work aims to evaluate the potentiality of the bimetallic nanoadsorbent ((TiO2@MnO2)-NPs) obtained from the biosynthesis in the mercury ions (Hg2+) removal by adsorption. (TiO2@MnO2)-NPs was synthesized from Aloe vera and Matricaria recutita extracts. The nanoadsorbent was characterized by XRD, ZP, and pHZCP. The results confirmed the production of a nanoadsorbent with an average particle diameter around 25 nm. (TiO2@MnO2)-NPs showed negative surface charge (− 11.32 mV), and pHZCP ≈ 7.65. Regarding Hg2+ adsorption, the removal was 86.15%. Adsorption data were fitted by Khan (R2 0.96, qe = 28.07 mg g−1) and intraparticle diffusion (R2 0.97, qt = 28.84 mg g−1) models. Thermodynamics suggested the adsorption is exothermic process (ΔH = − 73.93 kJ mol−1), with decrease of the randomness (ΔS = 0.24 kJ mol−1 K−1) in the solid–liquid interface, being favorable under temperature below 298.15 K (ΔG = − 1.16 kJ mol−1). (TiO2@MnO2)-NPs resulted in more than 80% Hg2+ removal after six cycles of adsorption. Therefore, nanoparticles containing titanium and manganese can be effectively used for the adsorption of Hg2+ ions, collaborating with the environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thiophene-based covalent organic polymers (BTT-COPs) were directly synthesized via the Schiff base reaction. • Plenty of heteroatoms in BTT-COPs act as active sites to absorb Hg2+ ions. • Ultra-fast adsorption of trace Hg2+ at 1000 μg L−1 in the presence of 12 competing ions is achieved. • The photothermal capacity of BTT-COPs under irradiation, facilitate the rapid desorption of Hg2+. • BTT-COPs enables exceptional selectivity and recoverability for Hg2+. Mercury is one of the most toxic heavy metals to humans. Developing highly efficient adsorbent for removing mercury is of great significance. Herein, two thiophene-based COPs were synthesized through Schiff base reaction by rationally selecting thiophene group as COP building block and functional component simultaneously, avoiding the drawbacks of functionalization strategy such as sacrificing the porous structure and blocking the active sites. The high S/N content in the COPs structure enables robust adsorption towards Hg(II), with maximum adsorption capacity up to 468.8 mg g−1. Notably, even in the presence of 12 interfering ions, the resulting COP-BTTS effectively reduced trace Hg(II) at 1000 μg L−1 to 33 μg L−1 within 30 s, achieving a removal rate up to 97 %, and below the regulatory discharge limit of 10 μg L−1 for wastewater in 15 min. Moreover, the temperature of COP-BTTS can rise to 140 °C-150 °C under xenon light due to its exceptional photothermal property, which can facilitate the efficient desorption of Hg2+. And the COP-BTTS maintains its exceptional recoverability after the successive repeated 5 cycles. This work sheds light on the feasible strategy for designing and synthesizing COP adsorbent with high adsorption capacity, selectivity, and irradiation-assisted desorption of metal ions. [ABSTRACT FROM AUTHOR]

Graphene-based materials are attractive adsorbents for water decontamination. In this work, we have produced eco-friendly reduced graphene oxide (rGO)-based sorbents by the hydrothermal reduction of graphene oxide (GO) in presence of caffeic acid (CA) and further modification with chitosan (CA_CS). Scanning electron microscopy observations show porous macrostructures that turn more compact after CA or CA_CS modification. The specific surface area achieves a maximum value of 293 m2 g−1 for the pristine rGO foam. The macropores are mainly distributed in a range between 1–170 µm. The Hg2+ removal efficiency of the rGO-based foams was investigated across several different parameters. The foam modified with caffeic acid exhibited the most promising performance, demonstrating the highest removal efficiency at pH 4–6, with a maximum sorption capacity of 2.79 mg/g as determined by the Sips equation. Kinetic analysis indicates that intraparticle diffusion and the sorption itself are the rate-limiting steps. The notable sorption efficiency, the low desorption rate, and the applicability in real complex water matrices, including tap water, position rGO_CA as a viable material for efficiently capturing Hg(II) from large volumes of water and securely storing it in a small solid volume. [Display omitted] • Graphene-based adsorbents are attractive for water decontamination. • Reduced graphene oxide (rGO)-based sorbents are synthesized hydrothermally using caffeic acid. • The specific surface area achieves a maximum value of 293 m2 g−1 for the pristine rGO foam. • 25 mg/L of rGO_CA foam reduces the Hg2+ to a residual concentration of less than 10 µg/L in 24 h. • The foam revealed an optimum pH for Hg2+ removal between 4–6. [ABSTRACT FROM AUTHOR]

Developing new chemically recyclable polymers is important for a circular plastics economy. Herein, we prepared a class of 1,4-dithian-2-one (DTO) with thioether and thioester functionalities. These sulfur-substituted monomers (DTO) showed excellent reactivity for ring-opening polymerization (turnover frequency (TOF) up to 2.3 × 104h−1), which afforded poly(thioether-thioester)s (P(DTO)s) with high air stability, high crystallinity, and commercial high-density polyethylene-like mechanical property (σB = 29.59 ± 1.08 MPa and εB = 749% ± 36%). Intriguingly, chemical recycling of P(DTO) to monomer could be accomplished with excellent efficiency in dilute solution (1 min) at room temperature or even from a commodity plastic waste mixture under catalyst-free thermal bulk condition (180 °C), thus establishing its circular life cycle. P(Me-DTO) could be applied for selective removal of Hg2+ with >99% removal efficiency. More importantly, Me-DTO could be recovered in high yield after utilization for Hg2+ adsorption. [ABSTRACT FROM AUTHOR]

Sulfur-doped biochar (S 4 BC) was prepared with cherry kernel powder as carbon source, Na 2 S 2 O 3 as sulfur source and chemical activator. Na 2 S 2 O 3 can activate biochar through the reaction with carbon, intercalation of alkali metals and the generated gas rushing out of pores, and at the same time, active sulfur atoms are doped into biochar during pyrolysis. The physical and chemical properties of S 4 BC adsorbent were evaluated by various characterization techniques. The results show that S 4 BC calcined at 800 °C has huge specific surface area of 959.6 m2/g, developed pore structure, and high content of S (18.84 wt%). Moreover, due to the existence of sulfur and oxygen functional groups, S 4 BC-800 provides sufficient active sites for the adsorption of Hg2+. According to Langmuir model, the maximum adsorption capacity of S 4 BC-800 for Hg2+ is 724 mg/g at 313 K, and the adsorption speed is fast with excellent stability and reusability. The microfiltration membrane device based on S 4 BC-800 can effectively remove the low concentration of Hg2+ in the solution. In this study, a simple method for preparing SBC materials is developed, which is not only of great significance as an adsorbent for Hg2+, but also provides a new choice for the preparation of heteroatom-doped materials. [ABSTRACT FROM AUTHOR]

Biochar adsorbents are obtained from rice straw under an air atmosphere through a simple eutectic salt (K 2 CO 3 +Li 2 CO 3) synthesis approach. Pristine biochars present relatively low mercury capture ability probably due to their small specific surface areas with less adsorption sites. Deposition of CuS can notably strengthen the mercury adsorption ability of the biochars. The best CuS content is 5 wt% associated with nearly complete mercury capture within 60–100 °C. The Hg0 removal ability of CuS-doped biochars are subtly degraded by NO and negligibly affected by SO 2. Cu2+ and S2− species function as adsorption sites, resulting in the production of HgS accompanied by the reduction of partial surface Cu2+ ions into low-valence Cu+ ions. • Biochars are facilely obtained via a molten salt method under air atmosphere. • The rice straw derived biochars are employed for Hg0 removal from flue gas. • CuS addition could notably reinforce the Hg0 capture performances of biochars. • NO and SO 2 show slight impacts on Hg0 removal abilities of CuS-doped biochars. [ABSTRACT FROM AUTHOR]

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Mercury (Hg) pollution poses a significant environmental challenge. One promising method for its removal is the sorption of mercuric ions using biochar. FeS-doped biochar (FBC) exhibits effective mercury adsorption, however may release excess iron into the surrounding water. To address this issue, a novel magnetic pyrrhotite/magnetite-doped biochar with a core-shell structure was synthesized for the adsorption of 2-valent mercury (Hg(II)). The proposed synthesis process involved the use of algae powder and ferric sulfate in a one-step method. By varying the ratio of ferric sulfate and alga powder (within the range of 0.18 - 2.5) had a notable impact on the composition of FBC. As the ferric sulfate content increased, the FBC exhibited a higher concentration of oxygen-containing groups. To assess the adsorption capacity, Langmuir and Freundlich adsorption models were applied to the experimental data. The most effective adsorption was achieved with FBC-4, reaching a maximum capacity (Q m) of 95.51 mg/g. In particular, at low Hg(II) concentrations, FBC-5 demonstrated the ability to reduce Hg(II) concentrations to less than 0.05 mg/L within 30 min. Additionally, the stability of FBC was confirmed within the pH range of 3.8 - 7.2. The study also introduced a model to analyze the adsorption preference for different Hg(II) species. Calomel was identified in the mercury saturated FBC, whereas the core-shell structure exhibited excellent conductivity, which most likely contributed to the minimal release of iron. In summary, this research presents a novel and promising method for synthesizing core-shell structured biochar and provides a novel approach to explore the adsorption contribution of different metal species. [Display omitted] • Pyrrhotite/magnetite and biochar formed core-shell structure in FBC. • High sorption effective at low Hg(II) concentration by FBC-5. • Sorption preference of different Hg(II) species investigated by a new model. • FBCs have almost no iron release within pH range of 3.8-7.2. • FBCs can adsorb multiple heavy metals. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Here we report a novel class of low-cost sulfhydrylated cellulose adsorbents. • Sulfhydrylated cellulose is synthesised by a simple and sustainable synthetic route. • Sulfhydrylated cellulose has a high selectivity and adsorption capacity for Hg(II). • It has a high Hg(II) removal efficiency even in wastewater. [ABSTRACT FROM AUTHOR]

Microcrystalline cellulose microsphere was functionalized by using radiation-induced grafting polymerization and following modification. The adsorption performances of the L-cysteine and pentaethylenehexamine functionalized resin (named CysMC and PMC) toward mercury (Hg) were tested by batch experiment. The experimental isotherm data were both well described by the Langmuir isotherm model. The results showed the maximum adsorption capacity for Hg(II) by CysMC and PMC were calculated to be 264.55 and 169.49 mg/g, respectively. The adsorption kinetic data were well fitted by the pseudo-second-order model for both CysMC and PMC. Thermodynamic studies indicated the Hg(II) adsorption was endothermic by CysMC but exothermic by PMC. The selectivity and repeated use were investigated. The two adsorbents can removal Hg(II) from an aqueous solution selectively and good repeated use performance. Moreover, X-ray photoelectron spectroscopy analysis was used to demonstrate the adsorption mechanism. [ABSTRACT FROM AUTHOR]

Mercury and cadmium are deemed to be the most harmful heavy metal ions for elimination due to their persistent bio‐accumulative and bio‐expanding toxic effects. Although many technologies have been developed for capturing Hg(II) and Cd(II) ions from aqueous solution, developing efficient and practical capature technology remains a big challenge. Metal‐organic frameworks (MOFs) have been considered as the most promising adsorbents for Hg(II) and Cd(II) removal due to their high porosity and easy functionalization, and various of MOF‐based adsorbents based on different synthetic strategies have been prepared and studied. In this article, the progresses of MOF‐based absorbents for Hg(II) and Cd(II) capture are described according to the synthetic strategies and the types of functional groups, and the comparison and practical analysis of various adsorbents are also presented. [ABSTRACT FROM AUTHOR]

The possibility of using the PSTC-3F synthetic organosilicone sorbent for the adsorption removal of mercury from an aqueous solution has been studied. The dependence of mercury adsorption on the pH of the solution, the amount of the adsorbent and the duration of the contact of the solution with the adsorbent is examined. It is shown that the higher the solution acidity is, the higher the adsorption value is. It has been established that the mercury adsorption process on the PSTC-3F sorbent is described by the Freundlich equation. [ABSTRACT FROM AUTHOR]

The removal of Hg from contaminated aquatic media is of major importance, taking into consideration the highly toxic character of the element. One of the most promising water treatment technologies is adsorption by low cost adsorbents, such as activated carbon produced by agricultural byproducts. In this study, activated carbon in granular form (GAC) was produced using pistachio shells from Aegina Island (Greece). Two main GAC products have been synthesized. The first one was chemically activated using ZnCl2. The second one was further treated with Na2S in order to introduce S atoms on the functional groups. The effectiveness of synthesized GAC products for Hg removal was evaluated by conducting batch equilibrium and kinetic experiments. It was found that sulfurization was able to increase by a factor of more than 2 the adsorptive capacity of activated carbon. Namely the maximum adsorption capacity was 73 mg/g for the simple GAC and increased up to 166 mg/g for the S-modified product. The kinetics of adsorption was described with almost equivalent precision using the pseudo-first and the pseudo-second order models, a behavior which is often observed in adsorption experiments, depending on the experimental conditions. The value of activation energy EA was found to be negative (− 18.8 kJ/mol) in the case of simple GAC and positive (8.27 kJ/mol), in the case of S-modified GAC, suggesting that Hg adsorption on the modified carbon follows a different mechanism, closer to chemisorption processes. [ABSTRACT FROM AUTHOR]

The nano-ceramic which is mesoporous silica material was applied to test the removal efficiency of gas-phase Hg0 using a fixed-bed reactor. The physical and chemical properties of nano-ceramic were investigated by various techniques such as BET surface area (BET), X-ray diffraction, fourier transform infrared spectrometer (FTIR), and scanning electron microscope (SEM); then, the sample was tested for mercury adsorption under different conditions. The mercury adsorption tests shown that different Hg0 concentration, adsorption temperature, gas flow rate, and different gas components have significant effects on the mercury removal performance of nano-ceramic, and the adsorption removal rate of nano-ceramic can be 75.58% under the optimal experimental conditions. After fitting the experimental data to the adsorption model, it was found that the theoretical maximum mercury adsorption amount q max of nano-ceramic is 1.61 mg g−1 and there were physical and chemical adsorption at the same time. The adsorption kinetics fitting results shown that the adsorption process of nano-ceramic exhibits multi-segment characteristics of "transmembrane–diffusion–adsorption." [ABSTRACT FROM AUTHOR]

The escalating issue of mercury (II) ions (Hg2+) pollution in water, primarily due to human activities, poses a significant environmental and health risk. Addressing the urgent need for efficient Hg2+ removal, this study introduces a novel porous organic polymer (TpTHU) synthesized through Schiff base condensation of thiourea (THU) and 1,3,5-Triformylphloroglucinol (Tp). TpTHU, enriched with sulfur and nitrogen, facilitates soft–soft interaction with Hg2+, offering a potent solution for mercury contamination. Our experimental results demonstrate TpTHU's remarkable adsorption capacity for Hg2+, reaching 1250 mg/g, attributed to its dense complexation sites. The adsorption behavior aligns well with the Brouers-Sotolongo model. Notably, TpTHU achieves 99.25% mercury removal within 120 min over a broad pH range (4 to 10), underscoring its rapid action. Additionally, in fixed-bed column experiments, TpTHU effectively lowers Hg2+ concentrations in industrial wastewater from 10.0 mg/L to below 5 μg/L, surpassing industrial emission standards. Through XPS analysis and density functional theory calculations, we elucidate the adsorption mechanism, affirming TpTHU's efficiency. With its straightforward synthesis, high efficacy, and excellent reusability, TpTHU emerges as a promising candidate for mitigating Hg2+ pollution in industrial wastewater. • The novel porous organic polymer TpTHU demonstrated robustness and reusability in the removal of Hg2+. • Demonstrated TpTHU's high Hg2+ adsorption capacity and rapid kinetics. • Proved TpTHU's effectiveness in treating Hg2+-contaminated industrial wastewater via fixed-bed experiments. • Elucidated the adsorption mechanism of TpTHU through XPS and density functional theory analysis. [ABSTRACT FROM AUTHOR]

A high‐performance bagasse‐based adsorbent was prepared from agricultural waste bagasse by grafting of acrylamide and aminating with diethylenetriamine. Effects of catalyst dosage, acrylamide concentration, reaction temperature, and bath ratio on the grafting yield were investigated. The adsorption performances for mercury ions were evaluated by batch adsorption experiments and kinetic experiments. The results show that the adsorbent has high adsorption capacity for mercury in a wide range of pH values. The adsorption capacity could be as high as 813.0 mg/g, and the removal percentage for mercury ions can reach 99.9%. The kinetic adsorption experiments show it can achieve adsorption equilibrium rapidly, which implies that the adsorbent has a strong ability to capture mercury ions. Besides, the bagasse‐based adsorbent showed promising regeneration performance, and its adsorption amount of regenerated adsorbent only slightly decreased after five recycling. Practitioner points: An amino‐rich adsorbent was prepared from bagasse.The adsorbent possesses high adsorption capacity and high removal efficiency for mercury.The aminated bagasse adsorbs mercury rapidly.The adsorbent functionalized with amino possesses strong affinity toward mercury. [ABSTRACT FROM AUTHOR]

This study examined the selective removal of gaseous mercury contained in combustion flue gas by potassium iodide (KI) loaded on activated carbon fibers (ACF). Activated carbon, such as ACF, although a useful mercury sorbent, shows poor performance in the direct treatment of high-temperature flue-gases because it removes mercury only by physical adsorption. KI can remove mercury at high temperatures via a gas-solid reaction between mercury and adsorbents, and it has been confirmed experimentally that it shows high mercury removal performance in the temperature range of 100–200 °C. On the other hand, KI in the absence of a porous support with a high surface area has low mercury-adsorption removal efficiency. Hence, a high surface area support is needed for adsorption removal. In the present study, mercury contained in combustion exhaust gas could be removed efficiently using KI as an adsorption activity enhancer on an activated carbon fiber (ACF), which provided a high surface area. [ABSTRACT FROM AUTHOR]

• Copper-manganese spinel-type oxides were synthesized to capture Hg0 from flue gas. • CuMn 2 O 4 exhibits excellent regenerability and recyclability for mercury removal. • Mercury desorption from the spent sorbent is a first-order reaction process. • Mobile-electron environment is responsible for the superior performance of CuMn 2 O 4. To capture elemental mercury from flue gas, a series of novel Cu-Mn spinel-type sorbents were synthesized using the proposed low-temperature sol-gel auto-combustion synthesis method. CuMn 2 O 4 sorbent exhibited excellent mercury removal performance in a wide temperature window of 50–350 °C, which is closely related to the mobile-electron environment caused by the Jahn-Teller distortion. The adsorbed mercury species exist in the forms of Cu-Hg amalgam and HgO on the sorbent surface. The chemisorption mechanism is responsible for Hg0 adsorption on CuMn 2 O 4 surface. Mercury removal by CuMn 2 O 4 sorbent is controlled by mass transfer process when the superficial velocity of flue gas is less than 16.9 cm/s. The surface reaction kinetics dominates mercury removal process when the superficial velocity is larger than 16.9 cm/s. The results of repeated adsorption-regeneration experiments indicate that CuMn 2 O 4 sorbent exhibits excellent regenerability and recyclability for mercury removal from flue gas. During the regeneration process, the gas-phase O 2 in air can decompose over sorbent surface to regenerate the consumed chemisorbed oxygen and replenish the oxygen vacancy. Mercury desorption from spent sorbents is a first-order desorption reaction process. The pre-exponential factor and activation energy for Hg0 desorption from used sorbent surface are 1.06 × 104 s−1 and 61.43 kJ/mol, respectively. [ABSTRACT FROM AUTHOR]

The present study reports on a novel microwave assisted route of synthesis of carboxymethylchitosan-g-polymethylmethacrylate (CMCS-g-PMMA). The synthesized samples were characterized by Fourier transform infrared (ATR-FTIR), 13C solid-state NMR spectroscopy, thermal analysis (TGA, DTGA and DSC), X-ray diffraction (XRD) and SEM analysis to provide evidence of successful grafting. The adsorption ability of mercury (II) from aqueous media on CS, CMCS and CMCS-g-PMMA was investigated. The equilibrium was reached within 90 min. The maximum adsorption capacity was found to be 68.69, 75.75 and 87.71 mg g−1 from the Langmuir isotherm model at 25 °C for CS, CMCS and CMCS-g-PMMA respectively. Our data reveal that Hg2+ removal by the used adsorbents follow the pseudo-second-order model. The thermodynamic study revealed that the adsorption process is spontaneous and exothermic. Besides, the adsorption was found to be physical. A polyethylene glycol -water treatment of the Hg2+ loaded adsorbents (CS, CMCS and CMCS-g-PMMA) desorbed about 96% of the scavenged ions. • Synthesis of carboxymethylchitosan-g-polymethylmethacrylate for metal removal. • Mercury adsorption onto CS, CMCS and CMCS-g-PMMA has been studied. • Langmuir isotherm is suitable to describe the adsorption process. • Thermodynamic properties of the adsorption process have been determined. • Adsorption mechanism, desorption and reusability of adsorbents were investigated. [ABSTRACT FROM AUTHOR]

The powder coke was obtained by three methods: carbonization, carbonization followed by activation（ twostep method） and simultaneous carbonization activation（ one-step method）, respectively, under the condition of simulated coal-fired hot gas in a drop-tube reactor. The biggest advantage of using the one-step method was that it can greatly simplify the process, and the investment were significantly reduced comparing with the other two methods. The active cokes obtained by three different methods were used to explore the adsorption property of Hg0, further, the effects of O2, SO2 and SO2+O2 on Hg0 removal efficiency were examined in flue gas. Besides, the desorption of Hg0 was explored and the regeneration experiments conducted under microwave and thermal methods were investigated. The results indicate that the active coke prepared by the one-step method has a large specific surface area, microporous specific surface area and abundant CO functional groups, thus has a better Hg0 removal efficiency than that of the other two methods, and the adsorption capacity was 6. 53, 3. 62 and 5. 41 μg/g in 3 h, respectively. The O2 provided reactive oxygen sites on the surface of the active coke, promoting the adsorption of Hg0 on the surface of the active coke. However, the SO2 exhibited effect on Hg0 removal due to the competitive adsorption between the SO2 and Hg0 on the active coke. Interestingly, the SO42-with strong oxidation ability would be formed when the O2 and SO2 were injected into the reactor simultaneously, which greatly promoted the chemical adsorption of Hg0. Furthermore, the spent active coke was desorption completely within 15 min by microwave, and its desorption rate was higher than that in high temperature condition. Secondary adsorption for the active coke was performed after the high temperature and microwave desorption, and the adsorption capacity after microwave desorption was remarkably improved comparing with thermal methods, where the adsorption amounts of 5. 962 and 7. 280 μg/g in 3 h were achieved. The reason was that microwave could reactivate the active coke and promote the formation of micropores in the microwave desorption process. [ABSTRACT FROM AUTHOR]

Abstract Controlling of pre-oxidation conditions can effectively enhance the aimed active functional groups via promoting the oxidation and grafting reaction on biochar's surface. Here, the effect of different nitric acid pre-oxidation concentration (NAPOC) was investigated on the type and content of active oxygen-containing functional sites during the pre-oxidation stage, as well as the active nitrogen-containing binding sites for the following grafting process. And the possible reaction mechanisms for introducing nitrogen/oxygen-containing functional groups such as amide, pyridinic, carbonyl, carboxyl, etc., into the surface by ethylenediamine (EDA) were proposed. The samples were characterized by various analyses including N 2 adsorption/desorption, Boehm titration, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Results showed that the NAPOC played a crucial role in promoting the formation of oxygen-containing initiators, and difference of NAPOC resulted in different reaction principles. At higher NAPOC, more carbonyl, carboxyl and hydroxyl functional groups were formed, which facilitated the decoration of nitrogen binding active sites of amide and pyridinic for mercury ions adsorption into the carbon lattice of mesoporous biomass-derived biochar (MBB). The proportions of micropore and mesopore remained basically unchanged, indicating that the decorated nitrogen/oxygen sites were highly uniformly dispersed in MBB's frame and thus resulted in high activity. The comparison of adsorption properties of MBB showed that MBB-25-EDA had the highest adsorption capacity of 153 mg g−1 at pH 6, confirming that the 25% was the optimum NAPOC for introducing nitrogen/oxygen functional binding sites for effectively anchoring mercury. Graphical abstract Image 1 Highlights • Nitric acid pre-oxidation has a great effect on nitrogen/oxygen active decoration sites. • The decorated N/O sites on mesoporous biochar were uniformly dispersed. • More N/O active sites on biochar can be doped at 25% HNO 3 pre-oxidation concentration. • N/O active decoration sites promote the mercury adsorption on biochar. • The possible N/O doping and mercury adsorption mechanisms on biochar were proposed. [ABSTRACT FROM AUTHOR]

Highlights • Porous carbon-supported CuCl 2 was synthesized to remove Hg0 from syngas. • CuCl 2 -PC exhibited superior Hg0 adsorption ability at 200 °C. • Effects of syngas components on Hg0 adsorption were clarified. • XPS analyses were applied to identify the Hg0 adsorption mechanism. Abstract A series of sorbents based on biomass-derived porous carbon-supported CuCl 2 (CuCl 2 -PC) were synthesized and employed for elemental mercury (Hg0) removal from the syngas. The CuCl 2 -PC sorbent with a Cu mass content of 5.6 wt% exhibited superior Hg0 adsorption ability (98.5%) at 200 °C. The meso-/micropores structure of porous carbon is favorable for the well-dispersing of CuCl 2 in the inner pores with the formations of abundant Cu and Cl active sites, and beneficial for Hg0 fast transfer among pores, thereby enhancing the effective collision of Hg0 with active sites. Hg-Cu compound and mercury chlorides could be formed by the reactions of Hg0 with Cu and Cl species. The effects of syngas components on Hg0 adsorption ability of sorbent were investigated. HCl improved Hg0 adsorption by increasing the Cl concentration on sorbent surface. CO, H 2 S and H 2 O did not exhibit notable effects on Hg0 adsorption. Although H 2 could not affect the surface chemistry of sorbent, it could occupy the inner pores of sorbent, thereby making the interactions of Hg0 with active sites difficult. The amount of Cu2+ on sorbent surface decreased after Hg0 adsorption, indicating that the oxidation state of copper changed from Cu2+ to Cu+ under syngas atmosphere. [ABSTRACT FROM AUTHOR]

Abstract Novel adsorbents with low cost and high efficiency that do not produce secondary pollutants are vital for removing gaseous elemental mercury (Hg0) from coal-fired power plants. In this study, eight diatomite-based adsorbents were developed and used to remove Hg0 in a bench-scale fixed-bed reactor. The effects of active substances, reaction temperature, and gas components on the Hg0 removal performance of diatomite (Dia) and the mechanisms were investigated. After modification, the specific surface area of diatomite increased by 2-to-12 fold, and the Hg0 removal performance was greatly improved. The Hg0 removal efficiencies of the adsorbents decreased in the following order: I-Dia > Br-Dia > Cl-Dia. The Hg0 removal efficiency of CuBr 2 -Dia reached 91% in the simulated flue gas at the optimal reaction temperature (140 °C). The simultaneous presence of O 2 and HCl promoted the Hg0 removal by CuBr 2 -Dia. NO alone also played a significant role in Hg0 removal. However, SO 2 exhibited clear inhibitory effect. The average Hg0 removal efficiencies of CuBr 2 -Dia were 60% under 1200 ppm SO 2 , 87% under 1200 ppm SO 2 + 300 ppm NO, and 93% under 4% O 2 + 1200 ppm SO 2 + 300 ppm NO. The changes in the active adsorption sites caused by NO, and those caused by NO + SO 2 were different and irreversible. During the Hg0 removal process, Hg0 was oxidized to the Hg2+ or Hg+ species, while Cu2+ and Br radicals were reduced to Cu+ and Br−, respectively. Graphical abstract Unlabelled Image Highlights • Low cost and high efficiency adsorbents needed for Hg0 removal from flue gas. • Diatomite-based adsorbents exhibited excellent performance for Hg0 removal. • CuBr 2 -Dia had high Hg0 removal efficiency at 60–180 °C. • NO alleviated the inhibitory effect of SO 2 on Hg0 removal by CuBr 2 -Dia. • NO and NO + SO 2 caused distinct changes in the surface chemistry of adsorbent. [ABSTRACT FROM AUTHOR]

• Two models, Cu-O 2 /CeO 2 and CuO/CeO 2, are built to study the adsorption of Hg0, SO 2 , and H 2 O. • Cu-O 2 /CeO 2 has a much larger Hg0 adsorption energy than CuO/CeO 2 , resulting in a stronger mercury oxidation ability. • SO 2 tends to be adsorbed on copper sites on both surfaces. • Cu-O 2 /CeO 2 uses ambient O 2 instead of oxygen on CeO 2 for hydrolysis, resulting in better water resistance. Copper species dispersed on ceria have emerged as promising catalysts for various energy and environmental applications. However, the presence of water vapor in the actual application environment can significantly hinder the catalyst activity. Flame-synthesized catalysts have been found to possess good water resistance as well as strong mercury oxidation and sulfur resistance. In this study, two types of copper-cerium binary structures were compared: Cu/CeO 2 and CuO/CeO 2 , which represent highly dispersed copper on the CeO 2 lattice surface (the main structure of the flame-synthesized catalyst) and CuO clusters supporting on the CeO 2 lattice (the main structure of catalyst synthesized by impregnation methods), respectively. The adsorption energies of SO 2 , H 2 O, and Hg0 over these structures were studied by density functional theory calculations. The results revealed that Cu-O 2 /CeO 2 (Cu/CeO 2 with absorbed O 2) had the highest Hg0 adsorption energy (−81.4 kJ/mol), followed by CuO/CeO 2 (−13.1 kJ/mol) and CeO 2 (−4.4 kJ/mol). Both Cu-O 2 /CeO 2 and CuO/CeO 2 showed improved sulfur resistance compared to CeO 2 , because SO 2 was preferentially absorbed on copper sites, protecting the active sites on the CeO 2 surface·H 2 O was absorbed and hydrolyzed into hydroxyl groups on the surfaces of all structures. The hydrolysis process consumed active oxygen on the CeO 2 surface for CeO 2 and CuO/CeO 2 , but consumed oxygen absorbed from the surrounding air for Cu-O 2 /CeO, leading to its best water resistance among the three. This finding opens up possibilities for the development of highly efficient and water-resistant catalysts. [ABSTRACT FROM AUTHOR]

UiO-66 is an extremely versatile metal organic framework (MOF) due to its remarkable water stability and high specific surface area. The incorporation of modified chemical and structural defects (missing linker and missing cluster defects) into the crystalline UiO-66 by the simultaneous use of an amino modified ligand and a thiol containing monocarboxylic acid modulator (thioglycolic acid, TGA) during synthesis resulted in developing a novel dual-functional MOF, designated as NH 2 -UiO-66-SH_C. This material was characterized using FTIR, XRD, FESEM, EDX, XPS, BET and Zetasizer to explore the morphological integrity and chemical composition. NH 2 -UiO-66-SH_C crystals demonstrated irregular nano-sized morphology (< 100 nm) and microporous nature with specific surface area of 519.6 m2/g. The material was subsequently tested to adsorb the highly toxic aqueous mercury (Hg) which is responsible for severe damages to human health. The maximum adsorptive capacity for aqueous inorganic mercury was 885 mg/g at 303 K. The optimum adsorbent dose and solution pH were 0.3 g/L and 5, respectively. The adsorption was endothermic and followed pseudo-second order kinetics. The developed nano-adsorbent illustrated enhanced sorption capacities which were far higher compared to its parent MOFs (UiO-66 as well as NH 2 -UiO-66) and other reported modified forms of UiO-MOFs. A regeneration method that was effective over 5 cycles (Hg removal efficiency > 90%) was also reported. Overall, this study reports the development of a newly modified nano-crystalline MOF, by manipulation of the synthetic chemistry (with defect modulation), which is a promising adsorbent for Hg (II) in aqueous phase. [Display omitted] • Solvothermal synthesis of bi-functional (amine and thiol) MOF was reported. • Crystal defects were induced by thioglycolic acid in MOF structure. • Adsorption capacity of 885 mg/g for Hg (II) was obtained with excellent selectivity. • The adsorption was endothermic and followed pseudo-second order kinetics. • Chemisorption was identified as the governing adsorption mechanism. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel class of conjugated micro-mesopores poly(aniline)s (CMMPAs) was reported. • Mesopore in CMMPAs is facile created and " in-situ " decorated by ZIF-7-NH 2. • CMMPAs show extraordinarily fast kinetics rate, high capacity and super selective features. • Hg (II) could be removed from 10 ppm to 2 ppb in 2 s using our POU filtra-adsorption units. • Diffusion coefficient k 2 relates to mesopore volume V within 15–50 nm, i.e. k 2 = 0.0215 V -0.000079. Attempts to develop adsorbents for toxic Hg (II) removal from wastewater in an all-round high-capacity, rapid-kinetic and super-selective manner remain interesting but unsolved. Here, we report a novel class of conjugated micro-mesoporous poly(aniline)s (CMMPAs) by an ingenious integrated porosity design and decoration over porous organic polymers (POPs). We pre-create unstable ZIF-7-NH 2 and crosslink it into POPs but remove it subsequently through a time-saving acid wash to allow the formation of mesopores and the " in-situ " decoration of ZIF-7-NH 2 ligands as adsorption sites on the pore wall. The resulting adsorbent exhibits an ultra-high capacity of 1032 mg g−1, extremely fast kinetic with h of 1425 mg g−1 min−1 that could reduce Hg (II) from 10 to 1 ppm in 2 s and further to 2 ppb in ca. 30 min, and nearly 100% exclusive adsorption towards Hg (II). The mesopore volume within 15–50 nm as created is responsive to the diffusion coefficient k 2 (k 2 = 0.0215 V -0.000079); the outstanding capture is also essentially trigged by the unique affinity from N sites, thus highlighting CMMPA as an appealing platform for drinking-water purification that would significantly serve for practical environmental application. [ABSTRACT FROM AUTHOR]

Abstract Bamboo carbon (BC) is a renewable and low-cost material used as sorbent in the industry. Hydrogen peroxide (H 2 O 2) has been used to modify BCs to enhance its mercury adsorption ability. However, the mechanism of enhancement needs to be further investigated because the H 2 O 2 modification technique is environment-friendly. The Brunauer–Emmett–Teller (BET) method, ultimate analysis (UA), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were used to reveal the physicochemical characteristics of the modified BCs. Our results indicated that the action of H 2 O 2 on BC increased the number of C–O and OH oxygen functional groups on the surface of BC, thus significantly enhancing the efficiency of mercury adsorption. At the same time, H 2 O 2 modification increased the BET surface area of BCs. Increasing both the number of oxygen functional groups and BET surface area of BCs helped improve the adsorption of elemental mercury (Hg0). The presence of oxidized mercury (Hg2+) both in the flue gas and on the surface of BCs after the adsorption process indicated that chemisorption occurred on the surfaces of the H 2 O 2 modified BCs. Simulating a pseudo-second-order reaction model also demonstrated that the chemisorption of Hg0 occurred on the surfaces of H 2 O 2 -modified BCs. When compared with commercial activated carbon (AC), H 2 O 2 -modified BC was demonstrated to be a promising sorbent for mercury removal from flue gas. [ABSTRACT FROM AUTHOR]

Mercuric chloride supported on activated carbon was widely used as the catalyst for vinyl chloride monomer (VCM) production especially in Asia. The resultant depleted mercury-containing catalyst (DMC) was a hazardous solid waste due to the high mercury toxicity. Microwave heating (MWH) was used to decontaminate DMC. Effects of microwave power and treatment time on mercury removal efficiency were studied. Up to 99.98% of mercury could be recovered under the optimum treatment conditions of 700 W for 20 min with microwave energy consumption being 15.56 kW h kg −1 (DMC); meanwhile the treated DMC was a clean regenerated activated carbon (RAC) without mercury leaching toxicity. The obtained RAC was a satisfactory mercury adsorbent with high specific surface area (632.9 m 2 /g) and abundant surface functional groups. Then the RAC was used to absorb mercury from HgCl 2 solution. Effects of pH, adsorbent dose, agitation time and initial mercury concentration on mercury sorption were investigated. Reduction and ion exchange were mainly responsible for mercury sorption mechanisms. Adsorption process conforms to pseudo-second-order kinetic model and Langmuir adsorption isotherm model. The calculated adsorption capacity of RAC was 109.05 mg/g. The absorbed mercury was efficiently desorbed by MWH. High sorption capacity of RAC maintained after five times of cyclic sorption/desorption. This new process realized the recycling of secondary resource, providing a new idea for cleaner production of VCM in engineering applications. [ABSTRACT FROM AUTHOR]

The knowledge of the risks associated with the mercury pollution and the presence of mercury in gas processing plants has motivated the development of new efficient technologies for mercury removal from natural gas streams. In this work, the results of the physicochemical characterization of a synthetic adsorbent are used to understand the gaseous mercury adsorption process. The adsorbent is a mesoporous copper sulfide (Cu x S y )-hydroxyapatite with well-dispersed active sites presenting high-performance for mercury removal and fixation. Experimental results indicated that mercury migrates by diffusion into the mesopores where it is chemisorbed in two active sites located on the crystalline surface. These experimental results were considered in a phenomenological description of transport and adsorption processes resulting in a novel and more realistic mathematical model. In addition, experimental breakthrough curves at different conditions were used to validate the proposed mechanisms. The integration of experimental and modeling allowed an in-depth understanding of the adsorbents as well as the mercury removal process. [ABSTRACT FROM AUTHOR]

Effective, one-pot method of CNTs phosphonylation is presented. Cheap and readily available reagents are used, so the process can be easily transferred to large-scale production. The product was analyzed using spectroscopic methods (FTIR, UV-vis, XPS). Thermal properties of the bis-phosphonated nanotubes are reported for the first time. Newly obtained material was tested as an adsorbent for mercury removal from water. The sorption capacity for newly developed adsorbent was as high as 223.7 mg/g. The adsorption kinetics were studied within framework of Lagergren model, and Langmuir and Freundlich isotherms have been described. The effect of pH on the adsorption process has been evaluated and the optimal environmental conditions were determined to be neutral. The presence of bivalent ions Cd2+, Ni2+ in the solution did not affect adsorption efficiency of novel materials. [ABSTRACT FROM AUTHOR]

A new functionalized hybrid adsorbent is prepared by covalent grafting of thiosemicarbazide to the silica surface for the abatement of environmental mercury. The material was characterized using spectral techniques like SEM, TGA, FTIR, EDX and BET surface area analysis. The EDX images showed that the chelating ligand was successfully grafted on the surface. The material is analyzed as Hg(II) extractant by using radiotracer in batch experiments. Maximum adsorption capacity for the adsorbent is about 4.83 mg g −1 at pH 7, pHzpc 6.5 and equilibration time of 30 min. The kinetics are best described by Pseudo second order kinetic model (R 2  > 0.99). The equilibrium adsorption data are modeled with Langmuir, D-R and Freundlich isotherms. The adsorption capacity (0.05 mmol g −1 ) calculated from Freundlich model is in agreement with the experimental results (0.023 mmol g −1 ). Freundlich isotherm predicted heterogeneous nature of the sorbent surface and infinite surface coverage. The adsorption process of mercury is endothermic (ΔH = 27.53 J K −1 mol −1 ), favorable (ΔS = 106.13 J K −1 mol −1 ) and spontaneous (ΔG = − 3695.83 J mol −1 ) in nature, as suggested by thermodynamic investigations. [ABSTRACT FROM AUTHOR]

Mercury adsorption characteristics of Mississippi River deltaic plain (MRDP) freshwater marsh soil in the Louisiana Gulf coast were evaluated under various conditions. Mercury adsorption was well described by pseudo-second order and Langmuir isotherm models with maximum adsorption capacity of 39.8 mg g −1 . Additional fitting of intraparticle model showed that mercury in the MRDP freshwater marsh soil was controlled by both external surface adsorption and intraparticle diffusion. The partition of adsorbed mercury (mg g −1 ) revealed that mercury was primarily adsorbed into organic-bond fraction (12.09) and soluble/exchangeable fraction (10.85), which accounted for 63.5% of the total adsorption, followed by manganese oxide-bound (7.50), easily mobilizable carbonate-bound (4.53), amorphous iron oxide-bound (0.55), crystalline Fe oxide-bound (0.41), and residual fraction (0.16). Mercury adsorption capacity was generally elevated along with increasing solution pH even though dominant species of mercury were non-ionic HgCl 2 , HgClOH and Hg(OH) 2  at between pH 3 and 9. In addition, increasing background NaCl concentration and the presence of humic acid decreased mercury adsorption, whereas the presence of phosphate, sulfate and nitrate enhanced mercury adsorption. Mercury adsorption in the MRDP freshwater marsh soil was reduced by the presence of Pb, Cu, Cd and Zn with Pb showing the greatest competitive adsorption. Overall the adsorption capacity of mercury in the MRDP freshwater marsh soil was found to be significantly influenced by potential environmental changes, and such factors should be considered in order to manage the risks associated with mercury in this MRDP wetland for responding to future climate change scenarios. [ABSTRACT FROM AUTHOR]

The Hg2+ removal performance of fishbone charcoal prepared from discarded fishbone has been investigated in this work. The XRD, FTIR, and BET results demonstrated that the main composition of fishbone charcoal was hydroxyapatite and the specific surface area was 117 m2/g. The adsorption experiments indicated that fishbone charcoal had an extremely high adsorption capacity for Hg2+ (243.77 mg/g). The excellent Hg2+ adsorption capacity might be ascribed to the ion exchange of Hg2+ to the Ca2+ in the structure of fishbone charcoal, complexation of Hg2+ with ≡Ca(OH)2+ on the surface of fishbone charcoal, as well as electrostatic interaction between electronegative fishbone charcoal surface and cation Hg2+. This work transformed kitchen garbage (i.e., fishbone) into an effective mercury adsorbent with considerable capacity, giving a perspective sight for the utilization of solid waste. [ABSTRACT FROM AUTHOR]

Calcium carbide (CaC 2 ) is a potential feedstock for various alkynyl chemicals, but its actual activity is very low due to its high lattice energy and insolubility. A stirring ball mill was used here to intensify its reaction with perchloro-hydrocarbons (PCHCs), namely hexachlorobenzene (HCB), hexachloroethane (HCE), tetrachloroethene (TCE) and tetrachloromethane (TCM), forming corresponding alkynyl carbon materials (ACMs), viz. ACM HCB , ACM HCE , ACM TCE and ACM TCM , respectively. The reaction intensification may be ascribed to the activation of CaC 2 and its effective collision with PCHCs by the intensive impingement of the milling balls. The as-prepared ACMs were characterized by XRD, Raman, elemental analysis, XPS, SEM and BET analysis, and their adsorption performance was evaluated. These ACMs are mesoporous materials with over 70% carbon content, varying amount of acetylenic groups, rich micro-pores and high specific areas ranging from 270 to 970 m 2  g −1 . ACM HCB is found to be a promising sorbent with adsorption capacity of 514.7 mg-Hg g −1 for HgCl 2 aqueous solution and 24.4 mg-S g −1 for DBT oil, which is much superior to most of carbonaceous sorbents due to its rich micro-porosity and abundant acetylenic groups. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel hydrophilicity-tunable CMPA-CS polymer was prepared in-situ. • CMPA-CS exhibits ultrahigh adsorption capacity, rate and selectivity for Hg(II). • CMPA-CS efficiently reduces Hg(II) levels from 0.578 ppm in real water to 1.106 ppb. • The active and abundant O − and N − sites were responsible for Hg(II) adsorption. Conjugated microporous poly(aniline)s (CMPAs) are an intriguing material platform for the selective capture of toxic heavy metal ions from water. However, the hydrophobic, monotonous N heteroatom and microporous properties limit their application scopes, particularly for the in-depth treatment requiring to a parts per billion (ppb) level. Herein, we report a novel chitosan-anchored CMPA (CMPA-CS), as designed through delicately exploiting the chitosan as either adsorption sites or pore templates for CMPA to acquire highly functionalized mesopores that could considerably facilitate Hg(II) adsorption. The CMPA-CS thus displayed excellently wide pH suitability (1.0–13.0), large capacity (862.1 mg g−1), ultrafast removal rate (k 2 = 0.163 mg g−1 min−1), high affinity (K d = 7.1 × 106), and strong anti-interference performance (selectivity of minimum 94.5% under the extreme influence of 100-fold-concentration cations). Besides, the Hg(II) concentration could be decreased from 0.578 ppm to less than 1.106 ppb in Minjiang river water substrates, below the EPR drinking water standards of 2 ppb. Comprehensive characterization revealed that the removal mechanism of Hg (II) was primarily a synergetic chelation reaction from the unique nitrogen ligands and O-containing groups, with the following features intensified: (i) good wettability to increase the interaction between CMPA and Hg(II) as contributed by the plentiful oxygen-containing groups; (ii) hierarchical mesopores that would promote ions transport efficiency as created by the chitosan. The new insight in this work can offer valuable guidelines for the design and structure optimization of CMPAs, facilitating its real-world commercial implementation. [ABSTRACT FROM AUTHOR]

Micro-nano composite material was prepared to adsorb Hg(II) ions via the co-precipitation method. Oyster shell (OS), Fe3O4 nanoparticles, and humic acid (HA) were used as the raw materials. The adhesion of nanoparticles to OS displayed by scanning electron microscopy (SEM), the appearance of the (311) plane of standard Fe3O4 derived from X-ray diffraction (XRD), and the transformation of pore sizes to 50 nm and 20 μm by mercury intrusion porosimetry (MIP) jointly revealed the successful grafting of HA-functionalized Fe3O4 onto the oyster shell surface. The vibrating sample magnetometer (VSM) results showed superparamagnetic properties of the novel adsorbent. The adsorption mechanism was investigated based on X-ray photoelectron spectroscopy (XPS) techniques, which showed the process of physicochemical adsorption while mercury was adsorbed as Hg(II). The effects of pH (3−7), initial solution concentration (2.5−30 mg·L−1), and contact time (0−5 h) on the adsorption of Hg(II) ions were studied in detail. The experimental data were well fitted to the Langmuir isotherm equation (R2 = 0.991) and were shown to follow a pseudo-second-order reaction model (R2 = 0.998). The maximum adsorption capacity of Hg(II) was shown to be 141.57 mg·g−1. In addition, this new adsorbent exhibited excellent selectivity.

Functionalized graphene was efficiently prepared through ball-milling of graphite in the presence of dry ice. In this way, oxygen functional groups were introduced into material. The material was further chemically functionalized to produce graphene derivative with phosphonic groups. The obtained materials were characterized by spectroscopic and microscopic methods, along with thermogravimetric analysis. The newly developed material was used as an efficient mercury adsorbent, showing high adsorption efficiency. The adsorption isotherms were fitted using Freundlich and Langmuir models. The adsorption kinetics were fitted with pseudo-first order and pseudo-second order models. Adsorption selectivity was determined in the presence of cadmium ions and nickel ions. The presence of mentioned bivalent ions in the solution did not affect mercury adsorption efficiency.