Oxide Sorbents Research Articles

Deep insight into the effect of NaCl/HCl/SO2/CO2 in simulated flue gas on gas-phase arsenic adsorption over mineral oxide sorbents

Coal combustion is one of the major pathways by which arsenic enters the ecological environment. An effective method to control arsenic emissions in-furnace is to transform the arsenic from a vapour to fly ash particles using mineral sorbents. However, flue gas components have a significant effect on gas-phase arsenic adsorption, which limits the industrial application of mineral sorbents. In this paper, the effect mechanism of flue gas components (NaCl/HCl/SO2/CO2) on gas-phase arsenic adsorption over different mineral oxide sorbents was investigated. The results demonstrate that the order of arsenic adsorption is CaO > MgO/Fe2O3> NaCl > Al2O3 > SiO2. NaCl promotes the arsenic adsorption of CaO above 800 °C, and the arsenic removal efficiency of CaO with 5 % NaCl is 52.51 % at 900 °C. NaCl inhibits the arsenic adsorption of MgO and Fe2O3, and promotes arsenic adsorption by Al2O3 and SiO2. Acid gases inhibit arsenic adsorption by the sorbents and the order of the inhibition intensity of acid gases at 700 °C is HCl > SO2 > CO2. The active sites (CaO, FeO, or AlO bonds) in the sorbents are the main reaction sites for arsenic adsorption, and captured arsenic is in the form of AsO21− and AsO43-.

New titanium oxide sorbent for As(V) and Cr(VI) removal as well as La(III) and Nd(III) recovery

A new commercial sorbent ADSORBSIA™ As500 was used for As(V) and Cr(VI) removal as well as La(III) and Nd(III) recovery from aqueous solutions. The physicochemical properties were characterized by nitrogen adsorption/desorption analyses, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The adsorption kinetics of ADSORBSIA™ As500 was analysed using the reaction and diffusion base models such as the pseudo-first order, pseudo-second order, intraparticle diffusion, and Dumwald-Wagner. The effect of different pH values, dose, initial concentrations and the type of metal ions on the adsorption capacity was analysed. As for adsorption data, the Langmuir, Freundlich and Temkin models were used. Desorption of adsorbed metal ions from ADSORBSIA™ As500 was not studied. The sorption equilibrium was established within 60 min. The maximum amount of metals (qe) adsorbed at equilibrium was 37.98, 15.91, 24.77 and 22.23 mg/g for As(V), Cr(VI), La(III) and Nd(III), respectively, which can be arranged in the following selectivity order: As(V) > La(III) > Nd(III) > Cr(VI). The sorption capacities were found to be pH, time, concentration and sorbent dose dependent. The equilibrium data were well described by the Langmuir adsorption isotherm, but the kinetic data were fitted by the pseudo-second order model.

Advanced High-Temperature CO2 Sorbents with Improved Long-Term Cycling Stability.

Developing novel sorbents with maximum carbonation efficiency and good cycling stability for CO2 capture is a promising route to sequester anthropogenic CO2. In this work, we have employed a green synthesis method to synthesize CaO-based sorbents suitably stabilized by MgO and supported by in situ generated carbon under inert atmosphere. The varied amounts (10-30 wt %) of MgO were used to stabilize the CaO. The supported mixed metal oxide (MMO) sorbents were screened for high-temperature CO2 capture under CO2 rich (86% CO2) and lean (14% CO2) gas streams at 650 °C and atmospheric pressure. The MMO sorbents captured 53-63 wt % of CO2 per gram of sorbent under 86 and 14% CO2, accounting for about 98% carbonation efficiency, which outperforms the CO2 capture capacity of limestone derived CaO (L-CaO) sorbents (22.8 wt %). All of the synthetic MMO sorbents showed greater capture capacity and cyclic stability when compared to benchmark L-CaO. Because of the high carbonation efficiency and cycling stability of g-Ca0.69Mg0.3O sorbent, it was tested for 100 carbonation/regeneration cycles of 5 min each under CO2 lean conditions. The g-Ca0.69Mg0.3O sorbent showed exceptional CO2 capture capacity and cycling stability and retained about 65% of its initial capture capacity after 100 cycles.

Arsenic and cadmium removal from water by a calcium-modified and starch-stabilized ferromanganese binary oxide

A new calcium-modified and starch-stabilized ferromanganese binary oxide (Ca-SFMBO) sorbent was fabricated with different Ca concentrations for the adsorption of arsenic (As) and cadmium (Cd) in water. The maximum As(III) and Cd(II) adsorption capacities of 1% Ca-SFMBO were 156.25 mg/g and 107.53 mg/g respectively in single-adsorption systems. The adsorption of As and Cd by the Ca-SFMBO sorbent was pH-dependent at values from 1 to 7, with an optimal adsorption pH of 6. In the dual-adsorbate system, the presence of Cd(II) at low concentrations enhanced As(III) adsorption by 33.3%, while the adsorption of As(III) was inhibited with the increase of Cd(II) concentration. Moreover, the addition of As(III) increased the adsorption capacity for Cd(II) up to two-fold. Through analysis by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR), it was inferred that the mechanism for the co-adsorption of Cd(II) and As(III) included both competitive and synergistic effects, which resulted from the formation of ternary complexes. The results indicate that the Ca-SFMBO material developed here could be used for the simultaneous removal of As(III) and Cd(II) from contaminated water.

Multi-Metals CaMgAl Metal-Organic Framework as CaO-based Sorbent to Achieve Highly CO2 Capture Capacity and Cyclic Performance.

In this study, Ca-based multi-metals metal-organic framework (CaMgAl-MOF) has been designed as precursor material for carbon dioxide (CO2) capture to enhance the CO2 capture capacity and stability during multiple carbonation-calcination cycles. The CaMgAl-MOFs were constructed from self-assembly of metal ions and organic ligands through hydrothermal process to make metal ions uniformly distributed through the whole structure. Upon heat treatment at 600 °C, the Ca-based multi-metals CaMgAl-MOF would gradually transform to CaO and MgO nanoparticles along with the amorphous aluminum oxide distributed in the CaO matrix. XRD, Fourier transform infrared (FTIR), and SEM were used to identify the structure and characterize the morphology. The CO2 capture capacity and multiple carbonation-calcination cyclic tests of calcined Ca-based metal-organic framework (MOF) (attached with O and indicated as Ca-MOF-O) were performed by thermal gravimetric analysis (TGA). The single metal component calcined Ca-MOF sorbent have the highest CO2 capture capacity up to 72 wt.%, but a lower stability of 61% due to severe particle aggregation. In contrast, a higher Ca-rich MOF oxide sorbent with tailoring the Mg/Al ratios, Ca0.97Mg0.025Al0.005-MOF-O, showed the best performance, not only having the high stability of ~97%, but also maintaining the highest capacity of 71 wt.%. The concept of using Ca-based MOF materials combined with mixed-metal ions for CO2 capture showed a potential route for achieving efficient multiple carbonation-calcination CO2 cycles.

Efficient arsenic(III) removal from aqueous solution by a novel nanostructured iron-copper-manganese trimetal oxide

The removal of arsenite [As(III)] has attracted increasing attentions because it is higher toxic and more difficult to be removed from water than arsenate [As(V)]. For efficient As(III) uptake, a nanostructured iron-copper-manganese trimetal oxide (ICM) was therefore synthesized using a simultaneous oxidation and co-precipitation approach at room temperature. The as-prepared ICM exhibits multifunctional properties, which can not only oxidize effectively As(III) but also sorb the produced As(V). The maximal sorption capacity of As(III) reaches up to 131 mg/g under neutral conditions, which outperforms the majority of adsorbents reported in the literature. The As(III) sorption drops gradually as solution pH increases. However, it is not significantly influenced by ionic strength and present anions except for PO 4 3− , implying a relatively high selectivity. The active sorption sites of spent ICM can be easily restored through NaOH solution treatment. The removal of As(III) is a complicated process involving in both oxidation and adsorption, in which inner-sphere surface complexes are formed. The oxidation of As(III) to As(V) is mainly ascribed to the Mn oxide content in composite, whereas the adsorption of formed As(V) is predominately attributed to the Fe oxide and Cu oxide. The ICM might act as a promising alternative to remove arsenic from groundwater and wastewater, due to its good performance, low cost, facile synthesis and high reusability. • A novel nanostructured Fe-Cu-Mn trimetal oxide sorbent was fabricated. • The sorbent has a high sorption capacity for As(V) and As(III). • The sorbent is highly effective for As(III) removal at trace concentration. • As(III) uptake is mainly achieved by adsorption coupled with oxidation. • The spent sorbent can be easily regenerated and repeatedly used.

Atomically Dispersed Manganese on a Carbon-Based Material for the Capture of Gaseous Mercury: Mechanisms and Environmental Applications.

A novel, atomically dispersed carbon-based sorbent was synthesized by anchoring manganese atoms with N atoms for the capture of gaseous elemental Hg (Hg0). Oxygen atoms were also introduced into the synthesis process to adjust the oxidizing ability of the Mn atoms. High-valence Mn (Mn4+) anchored by the O and N atoms (Mn-O/N-C) in the carbon-based materials provided more exposed active sites. The mercury removal efficiency of the composite exceeded 99%. The composite with a Mn loading of 0.9 wt % exhibited high affinity for Hg0, and the capacity for Hg0 adsorption within 275 min at room temperature reached 16.95 mg·g-1. The Mn utilization was ∼56.61%, which is much larger than that of reported Mn-based oxide sorbents. The atomic-level distribution of Mn was well evidenced by aberration-corrected high-angle annular darkfield scanning transmission electron microscopy. Density functional theory calculations were conducted to evaluate the energy for adsorption of Hg0 on Mn-O/N-C. The results indicated that the amount of N and O atoms in the Mn coordination environment determined the Hg0 adsorption energy, and the presence of five optimized Mn adsorption structures in Mn-O/N-C was confirmed by Hg temperature-programmed desorption analysis. These materials may be utilized for mercury removal from disposal sites with high concentrations of mercury, broken mercury-containing lamps, or mercurial thermometers. The strategy of atomic dispersion during synthesis of the materials and adjusting the oxidizing ability in the single-atom strategy may be helpful for the development of environmentally benign functional materials.

Application of Molybdenum oxide nanoparticles in H2S removal from natural gas under different operational and geometrical conditions

Microporous and nanoporous metal oxides are potential adsorbents for separating H2S from natural gas. Structured porous adsorbents have the potential to improve the energy and production costs in gas separation and catalysis applications by providing higher production rates. Zinc, Manganese, and Iron oxide nanoparticles are among the most potential and most extensively employed materials. Applying this framework, other novel metal oxides have been recognized for separation of H2S from representative H2S/CH4. In the present study, we investigate the performance of Molybdenum oxide nano-particles as an adsorbent for H2S removal and compare it with the performance of zinc oxide nano-particles. The effects of operating conditions such as temperature (65–89 °C), pressure (10–19 bar), initial concentration of H2S in the feed stream (38–73 ppm), and space velocity (0.018–0.045 m s−1) on H2S adsorption from sour gas are evaluated. Our analysis shows that Molybdenum oxide nano-particles have an adsorption capacity of 0.081 and 0.074 g H2S/g Molybdenum oxide in low temperature and low concentration of H2S using non-spherical and spherical Molybdenum oxide sorbent, respectively. Proceeding by two adsorption isotherms, the Langmuir and Freundlich isotherms, analysis of variance displayed that both models can fit the adsorption data of H2S on Molybdenum oxide nanoparticles very well, while the Freundlich isotherm seems to provide R2 value of 0.98–0.99, indicating a better prediction of our experimental data.

Solution combustion synthesis of zirconia-stabilized calcium oxide sorbents for CO2 capture

Calcium looping process has not yet been commercialized due to challenges associated with the activity loss of CaO sorbents resulting from sintering of the particles in cyclic operations. In the present study, zirconia-stabilized calcium oxide sorbents have been developed through the solution combustion synthesis (SCS) method. The effects of preparation conditions (percentage of Zr stabilizer and fuel-to-metal oxide ratio) on the CO2 capture performance were investigated in a thermogravimetric analyzer. Sorbents with 20% calcium zirconate stabilizer and high fuel-to-metal oxide ratio exhibited an optimal combination of CO2 uptake capacity and stability. Increasing the fuel ratio improved the CO2 uptake capacity due to higher surface area and smaller particle size of the synthesized sorbents. However, increasing the ratio beyond six did not have any significant impact on the performance of the sorbent. Based on the results, the optimum fuel-to-metal oxide ratio for synthesis was six times the stoichiometric ratio. Two sorbents showing the best results (S20-4x and S20-6x) were tested in 50-cycle experiments under mild and harsh calcination conditions for long-term stability assessment. Sorbents displayed high uptake capacity (7.7 and 8.8 mol/kg, respectively, under mild conditions; and 5.0 and 6.5 mol/kg respectively, under harsh conditions) after 50 cycles, which is a significant improvement over the uptake of the benchmark limestone (4.1 and 1.7 mol/kg under mild and harsh conditions, respectively). Based on the results, Zr-stabilized sorbents prepared from solution combustion synthesis method are promising materials for calcium looping CO2 capture.

Theoretical and experimental investigation on improvement of magnesium oxide sorbent by acetic acid washing for enhancing flue gas desulfurization performance

Flue gas desulfurization (FGD) technologies are applied to minimize SO2 emission to the atmosphere and prevention of acid rains. Magnesium oxide (MgO) is one of the common sorbents to capture sulfur dioxide in FGD. Pore blockage and incomplete conversion are the main problems of sorbents such as CaO and MgO. In this study, acid-washed technique as a modification method was applied to enhance SO2 adsorption capacity of MgO. The tests were carried out in thermogravimeter (TG) and packed bed reactor to compare the performance of the acid-washed sorbents with the initial natural samples. The results showed that the acid-washed sorbents has more adsorption capacity than the natural samples. Finally, the single pellet conversion–time profiles and packed bed reactor breakthrough curves for both sorbents were predicted by random pore model (RPM) with fairly good agreements.

Microwave heating motivated performance promotion and kinetic study of iron oxide sorbent for coal gas desulfurization

High temperature coal gas desulfurization is an efficient and environment-friendly process for clean coal technologies. In this study, microwave heating is adopted as the energy source to prepare iron oxide desulfurization sorbents and the effect on the properties of the sorbents is investigated. Sorbent synthesized through the conventional heating method is obtained as well for comparison. Characterization techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), scanning electron microscope (SEM) and N2 adsorption are used to evaluate the as-prepared sorbents. Results from XAS and XRD show that Fe2O3 crystal possesses smaller volume and shorter length in bonds Fe-O and Fe-Fe, suggesting that there is a better dispersion of crystallites under microwave irradiation. According to XPS results, microwave irradiation induces sorbents with higher contents of surface lattice O2−, which is contributive to increasing the absorption efficiency and desulfurization reactivity towards the removal of H2S. With the help of thermogravimetry devices, kinetic studies produce the result that both the desulfurization and regeneration processes adapt the model of unreacted shrinking core. The reaction rates are limited via surface chemical reaction at first and then controlled by internal diffusion control in the later stage. Sorbents produced by microwave heating, on the whole, show a better H2S removal performance due to their facilitated chemical reaction and mass transfer, suggesting the potential of the preparation of improved industrial sorbents.

Pilot Test of the Permeable Reactive Barrier for Removing Uranium from the Flooded Gunnar Pit

This work reports on applying iron oxide coated sand (IOCS) media in an experimental permeable reactive barrier to remove uranium (U) species from uranium containing water. A field study was conducted at the legacy Gunnar uranium mine & mill site that was abandoned in the 1960s with limited to no decommissioning. The flooded Gunnar mine pit presently contains about 3.2 million m3 of water contaminated by dissolved U (1.2 mg/L), Ra-226 (0.4 Bq/L), and minor concentrations of other contaminants (As, Se, etc.). The water is seeping over the pit rim into Lake Athabasca, posing potential environmental and health concerns. IOCS media can be used to immobilize uranium species through an adsorption process. Herein, the preparation of hydrous ferric oxide sorbents and their supported forms onto silica sands is described. Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffraction (pXRD) were used for structural characterization. The adsorption properties of the IOCS sorbent media were modeled by the Langmuir adsorption isotherm, where a maximum uranium uptake capacity was estimated. Bench-scale adsorption kinetic experiments were also performed before moving to a field trial. Based on these lab results and input on field-scale parameters, a pilot permeable reactive barrier was fabricated and a field test conducted near the Gunnar pit in June 2019. This pilot test provided technical data and information needed for designing a full-scale permeable barrier that employs the IOCS media. This approach can be applied for in-situ water treatment at Gunnar and other legacy uranium sites.

Effect of lignite as support precursor on deep desulfurization performance of semicoke supported zinc oxide sorbent in hot coal gas.

In this study, four different semicoke supported zinc oxide sorbents were prepared by combining high-pressure impregnation and heat treatment using four different lignites (Zhaotong, Xiaolongtan, Huolinhe, and Shengli districts) as precursors of supports and zinc nitrate as precursor of the active component. Their desulfurization performances were studied in a fixed-bed reactor at 400 °C in simulated coal gas. The physico-chemical properties of raw lignites were investigated using chemical titration, nitrogen adsorption and thermogravimetry (TG). The physico-chemical structures of sorbents were characterized by atomic absorption spectrometry (AAS), X-ray diffraction analysis (XRD), nitrogen adsorption, and scanning electron microscopy (SEM). The results indicate that the lignite as support precursor plays a critical role in the desulfurization performance of the sorbent. It affects the desulfurization activity of the prepared sorbent by influencing the loading content and utilization rate of the active component of the sorbent. The sorbent HPZn/C(Z) prepared using Zhaotong lignite presents the best desulfurization performance owing to its higher content and utilization rate of the active component, with a 13.74 h breakthrough time with the breakthrough sulfur capacity of 3.69 g sulfur/100 g sorbent. It is found that the loading content of the active component depends on the pore structure of the raw lignite, how its pore structure changes in high-pressure impregnation process and the content of oxygen-containing functional groups on its surface. The utilization rate of the active component is associated with the pore structure properties of the sorbent formed during heat treatment.

H2S-Selective Catalytic Oxidation to Sulfur over Iron Oxide Sorbent Supported on Semi-Coke

Iron oxides modified by semi-coke sorbents (referred to as FeSC) were prepared by the hydrothermal impregnation method and were used for the selective catalytic oxidation of H₂S to sulfur. The physicochemical properties of samples were characterized by Brunauer–Emmett–Teller analysis, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry (TG), and X-ray photoelectron spectroscopy. The results showed that iron oxide could be highly loaded on semi-coke with a microporous structure and high specific surface area. Fe₂O₃ was considered the only major active component on the surface of the sorbent. Fe7SC stably maintained the catalytic performance at 180 °C with the longest breakthrough time and highest release sulfur capacity. There was no benefit to desulfurization with excess oxygen in the feed gas. Through further analysis by TG, elemental sulfur was confirmed to be the main product of the catalytic oxidation of H₂S. Besides, a possible mechanism of H₂S selective catalytic oxidation over sorbent was proposed, in which the key step was the oxidation of FeS into S⁰ and Fe³⁺ by O₂. Moreover, sorbent deactivation was mainly caused by pore structure blockage by the sulfur product.

Mesoporous Zn-Fe-based binary metal oxide sorbent with sheet-shaped morphology: Synthesis and application for highly efficient desulfurization of hot coal gas

Mesoporous Zn-Fe-based binary metal oxide sorbent for hot coal gas desulfurization was derived from the Zn-Fe-based layer double hydroxide (ZnFe-LDH). Considering the great disparity of the pH required for the precipitation of Zn2+ and Fe3+, a two-step approach, namely the co-precipitation (Zn2+ and Fe2+) plus subsequent H2O2 oxidation, was proposed for the synthesis of the ZnFe-LDH, the precursor of the sorbent. The preliminary synthesis mechanism of the ZnFe-LDH was discussed. The results reveal that the formation of the layered structure occurs during the oxidation step process rather than the precipitation stage. A series of LDH-derived double metal oxides (DMOs) with the Zn/Fe molar ratios ranging from 1:1 to 5:1 were obtained and contain both ZnO and ZnFe2O4. Furthermore, sheet-shaped morphology is observed for most of the DMOs. The desulfurization performance of the DMOs was evaluated over a fixed-bed reactor. The results indicate that the DMO with the Zn/Fe molar ratio of 5:1 performs best and has the highest sulfur capacity (25 g of sulfur per 100 g of sorbent) at 550 °C. The reaction kinetics was analyzed via the deactivation model. The sorbent has lower deactivation rate constants (0.0185–0.0282 min−1) compared to other Zn-based sorbents, beneficial for the sulfidation reaction. In comparison to ZnO, the DMO sorbent shows lower regeneration temperature. Furthermore, regeneration could effectively recover the plugged pore structure caused by the sulfidation reaction. In addition, the sorbents could maintain high sulfur capacity during four sulfidation-regeneration cycles, showing great potential for industrial desulfurization of hot coal gas.

Conductive polyaniline-graphene oxide sorbent for electrochemically assisted solid-phase extraction of lead ions in aqueous food samples

This work describes an electrochemical-assisted desorption method that has been developed for solid-phase extraction of metal ions (Pb2+), based on a well-ordered conducting sorbent: an array-like polyaniline nanofiber synthesized on the surface of graphene oxide (PANI-GO). Combining the advantages of the allowable mechanical deformation of GO with the reduced ionic-diffusion path of vertical PANI nanofibers, this method’s synergistic effect lends the prepared sorbent an enhanced stability and high analyte-desorption effectiveness. In terms of the adsorption and electrochemical-assisted desorption behavior of PANI-GO, the paper reports that the adsorption/desorption process is accompanied by the changes of the as-prepared sorbent in cyclic voltammetry, and that the prepared PANI-GO exhibits good anti-interference properties across various interference ions. Given optimal pH values, the limit of detection of the proposed method is 0.04 μg L−1; the repeatability relative standard deviation (RSD) and reproducibility RSD are 1.97% and 2.51%, respectively; and the method shows good recovery capability in the case of real beverage samples spiked with Pb2+.

Determination of 2,4-Dichlorophenoxyacetic acid in food and water samples using a modified graphene oxide sorbent and high-performance liquid chromatography

In the present work, dispersive micro-solid phase extraction (D-μ-SPE) method using magnetic graphene oxide tert-butylamine (GO/Fe3O4/TBA) nanocomposite, as an efficient sorbent, was applied for determining 2,4-dichlorophenoxyacetic acid (2,4-D) in water and food samples. Detection was carried out using high-performance liquid chromatography (HPLC) instrument. Influential parameters of D-μ-SPE such as sorbent and its amount, elution solvent and its volume, adsorption and desorption times and pH of sample solution were investigated and optimized. Under the optimized conditions, limit of detection and quantitation values were 0.007 and 0.02 μg/mL, respectively. Recovery data for several real samples were obtained within the range of 88.0–94.0% with a relative standard deviation (RSD) less than 7.5%. The proposed method was successfully applied to quantitative determination of 2,4-D in several vegetables and water samples.

Determining kinetic constants for reactions of zinc oxide sorbents with syngas components

Hot gas clean-up (HGC) technology uses special zinc oxide based sorbents. Sorbent attrition is one of the negative factors that should be improved. The current study has determined that one of the main reasons of sorbent reduction is interaction with syngas components, namely, carbon monoxide, hydrogen, methane and carbon (side reactions). In this study, kinetics of main reaction (h2s adsorption by zinc oxide) and side reactions were considered and compared. Models of chemical processes and mechanisms were considered as well. Complicated nature of HGC process was researched. It is stated that the process can run in three different phases (gas, solid, dust). Methods of TGA data calculation are presented and compared with literature. In syngas where hydrogen sulphide concentration is much lower than concentration of hydrogen and carbon monoxide, main reaction is dominant at temperatures near 300–500 °C. At 650 °C main reaction takes the second place after H2 reduction, and at 850°C it is the third after CO reduction (with diffusion resistance of product shell). Hydrogen reduction is more active than carbon monoxide reduction, that is why CO/H2 ratio in syngas should be increased for rising the HGC operation temperature. A wide range of processes (main and side reactions) was considered with the use of the same materials, equipment and methods.

A nanostructured composite polyhydroquinone/graphene oxide sorbent: synthesis and physical-chemical properties

The prospect of using nanostructured materials in sorption-desorption cycles is substantiated by their unique physical-chemical characteristics determining the performance properties of modern sorbents. Functional polymer compounds are increasingly being used as modifying additives to carbon matrices. The authors have developed a method for synthesizing an innovative nanocomposite based on 1,4-benzoquinone-modified graphene oxide. The product obtained is technically called “polyhydroquinone/graphene oxide” (PHQ/GO). Technological parameters of the nanocomposite production were comprehensively studied. Quantitative dependences of the effect of the ratio of the initial components participating in the synthesis on the degree of GO surface modification were revealed. It was established that the amount of the modifier grafted nonlinearly depends on the weight of the initial monomer. This is presumably due to concurrent occurrence of several chemical reactions during the 1,4-benzoquinone polymerization. The physical-chemical characteristics of the material synthesized were investigated implementing the following techniques: scanning electron microscopy/energy dispersive X-ray spectroscopy, Raman spectroscopy, and thermogravimetry. The results of studying the structural, physical-chemical and operational properties of the nanostructured composite developed suggest that this material can be used as an efficient universal sorbent for the purification of aqueous media from different contaminants.

New versatile zincic sorbent for tobacco specific nitrosamines and lead ion capture

New carbon-doped ferric zinc oxide sorbents were fabricated to capture the environment carcinogen tobacco specific nitrosamines (TSNA) efficiently in solution, following new adsorption model of electrostatic attraction instead of traditional geometric constraints. The influence of ferric content on the structure-property of the sorbents was systemically studied with XRD, N2 adsorption-desorption and SEM methods combined with the adsorption of TSNA in different solutions. New sorbent captured 99% of 4-methylnitrosamino-1-3-pyridyl-1-butanone (NNK) in simulated surface water and 40% of TSNA in the tobacco extract solution, more than activated carbon or zeolites. Ferric ZnO sorbent took about 15 min to reach the adsorption equilibrium in the NNK or Pb(Ⅱ) solution, faster than NaZSM-5 zeolite. Moreover, the adsorbed NNK on ferric ZnO sorbent decomposed at mild conditions for the first time, providing a new way to control environment pollution.