Content Of Oxygen-containing Groups Research Articles

Granular activated carbon supported polyethylene glycol modified nano-zero-valent iron immobilized microbial removal of 2,4-dichlorophenol in water

In recent years, the remediation of 2,4-DCP pollution using immobilized microbial technology has attracted increasing attention. Using granular activated carbon (GAC), polyethylene glycol 4000 (PEG-4000), ferrous sulfate, and sodium borohydride as raw materials, granular activated carbon loaded polyethylene glycol modified nano zero-valent iron composite material (PEG-nZVI/GAC) was prepared via a liquid-phase reduction method. Bacillus marisflavi, capable of degrading phenolic compounds, was immobilized on PEG-nZVI/GAC using an adsorption method to prepare immobilization of microorganisms by granular activated carbon loaded polyethylene glycol modified nano zero-valent iron (PEG-nZVI/GAC@B) for 2,4-DCP removal. Characterization analysis of immobilized microbes was conducted using transmission electron microscopy (TEM) and other methods to determine their physicochemical properties. Response surface methodology (RSM) was employed to optimize the conditions for 2,4-DCP removal, and the performance and mechanism of 2,4-DCP removal by PEG-nZVI/GAC@B were studied. The results indicate that nanoscale zero-valent iron (nZVI) was uniformly distributed in granular activated carbon, Bacillus marisflavi was successfully loaded onto PEG-nZVI/GAC, PEG-nZVI/GAC@B had a higher content of oxygen-containing groups on its surface, and exhibits good dispersibility, stability, and reusability. When the immobilized microbial dosage was 270.32 mg/L, the initial concentration of 2,4-DCP was 50.51 mg/L, and pH was 6.58, the predicted removal rate of 2,4-DCP was 96.53 %. Under these conditions, the actual removal rate of 2,4-DCP was 94.68 %. The removal of 2,4-DCP by PEG-nZVI/GAC@B involved adsorption by granular activated carbon, reductive dechlorination by nanoscale zero-valent iron, and degradation by Bacillus marisflavi. In conclusion, PEG-nZVI/GAC@B is an excellent immobilized microorganism for the removal of 2,4-DCP.

Iron oxyhydroxide catalyzes production of artificial humic substances from waste biomass

Production of artificial humic substances (AHS) from waste biomass will contribute to environmental protection and agricultural productivity. However, there is still a lack of a faster, more efficient and eco-friendly way for sustainable production. In this study, we proposed a method to accelerate the production of AHS from cotton stalks by mild pyrolysis and H2O2 oxidation in only 4 hours, and investigated the formation of AHS during biomass transformation. We found that the process increased the aromatic matrix and facilitated biomass transformation by enhancing the depolymerization of lignin into micromolecular phenolics (e.g., guaiacol, p-ethyl guaiacol, etc.). The optimum conditions of pyrolysis at 250 °C and oxidation with 6 mL H2O2 (5 wt%) yielded up to 19.28 ± 1.30 wt% artificial humic acid (AHA) from cotton stalks. In addition, we used iron oxyhydroxide (FeOOH) to catalyze biomass transformation and investigated the effect of FeOOH on the composition and properties of AHS. 1.5 wt% FeOOH promoted the increased content of artificial fulvic acid (AFA) in AHS from 10.1% to 26.5%, eventually improving the activity of AHS. FeOOH raised the content of oxygen-containing groups, such as carboxylic acids and aldehyde, and significantly increased polysaccharide (10.94%–18.95%) and protein (1.95%–2.18%) derivatives. Polymerization of amino acid analogs and many small-molecule carbohydrates (e.g., furans, aldehydes, ketones, and their derivatives) promoted AFA formation. Finally, carbon flow analysis and maize incubation tests confirmed that AHS were expected to achieve carbon emission reductions and reduce environmental pollution from fertilizers. This study provides a sustainable strategy for the accelerated production of AHS, which has important application value for waste biomass resource utilization.

Rational design of animal-derived biochar composite for peroxymonosulfate activation: Understanding the mechanism of singlet oxygen-mediated degradation of sulfamethoxazole

Animal-derived biochar are identified as a promising candidate for peroxymonosulfate (PMS) activation due to the abundant aromatics and oxygen-containing functional groups. The current investigation focuses on pig carcass-derived biochar (800-BA-PBC) by ball milling-assisted alkali activation. The results showed that 800-BA-PBC could effectively activate PMS and degraded 94.2% sulfamethoxazole (SMX, 10 mg/L) within 40 min. The reaction rate constant was found to be 47 times higher than that observed with PBC. The enhanced catalytic activity is mainly attributed to the increase in specific surface area, the increase content of oxygen-containing groups on the surface, and the formation of graphitic nitrogen. The quenching tests and electron paramagnetic resonance (EPR) analysis demonstrated that 1O2 is the main active species in the degradation of SMX. Moreover, the 800-BA-PBC + PMS system can maintain excellent degradation rate under different water quality, wide pH range, and the presence of different anions. The degradation pathways of SMX in the optimal system are also evaluated through intermediate identification and DFT calculation. These results indicate that the catalytic system has high anti-interference ability and practical application potential. This investigation provides new insight into the rational design of animal-derived biochar and develops a low-cost technology for the treatment of antibiotic containing wastewater.

The effects of formation and functionalization of graphene-based membranes on their gas and water vapor permeation properties

The gas and water vapor permeabilities of graphene-based membranes can be affected by the presence of different functional groups directly bound to the graphene network. In this work, one type of carboxylated graphene oxide (GO-COOH) and two types of graphene oxide synthesized i) under strong oxidative conditions directly from graphite (GO-1) and ii) under mild oxidative conditions from exfoliated graphene (GO-2) were used as precursors of self-standing membranes prepared with thicknesses in the range of 12–55 μm via slow-vacuum filtration preparation method. It was observed that the permeabilities for all tested gases decreased in order GO-2 > GO-1 > GO-COOH and depended on both the arrangement of graphene sheets and their functionalization. The GO-1 membrane with a high content of oxygen-containing groups showed the best performance for water vapor permeability. The GO-2 membrane with a thickness of 43 μm exhibited a disordered GO sheet morphology and, therefore, unique gas-separation performance towards H2/CO2 gas pair, showing high hydrogen permeability while keeping extremely high H2/CO2 ideal selectivity that exceeds the Robeson 2008 upper bound of polymer membranes.

Nitrogen-rich magnetic biochar prepared by urea was used as an efficient catalyst to activate persulfate to degrade organic pollutants

In order to fully exploit the potential of magnetic biochar-based persulfate (PS) systems, N was utilized to modify the magnetic biochar-based catalysts through impregnation-pyrolysis method. A typical antifungal drug, metronidazole (MNZ), is selected as the target pollutant to score the reactivity of as-synthetic nitrogen-rich magnetic biochar (NMBC) catalysts. In the modified system, 99.6% of MNZ was removed, 13.6 times of that in the unmodified system. Active radical verification experiments showed that 1O2 was the key active radical. Various characterization showed that the nitrogen-rich significantly improved the persistent free radical, defect degree, content of oxygen-containing groups, electrochemical conductivity and other catalytic activity related properties. Physicochemical characterization, Fe(II) semi-quantitative analysis and masking experiments confirmed that the doping of magnetic biochar with nitrogen increased its Fe(II) content (23.79 mg/g), approximately 2.6 times higher than that of pristine magnetic biochar. Moreover, N induces strong electron accretion of Fe atom through coordination bond, which leads to the increase of electron density on the Fe atom, which increases the content of Fe (II) in the material, thus improving the ability of the material to activate PS to generate 1O2, and promoting the degradation reaction of MNZ. This paper provides a method to improve the activation performance of magnetic biochar.

Synthesis of a Polymer Composite Based on a Modified Aminohumic Acid Tuned to a Sorbed Copper Ion

A composite based on amino-containing humic acid with the immobilization of multi-walled carbon nanotubes preliminarily tuned to a copper ion has been obtained. The synthesis of a composite pre-tuned for sorption by the local arrangement of macromolecular regions was obtained by introducing multi-walled carbon nanotubes and a molecular template into the composition of humic acid, followed by copolycondensation with acrylic acid amide and formaldehyde. The template was removed from the polymer network by acid hydrolysis. As a result of this tuning, the macromolecules of the composite "remember" conformations that are favorable for sorption, i.e., adsorption centers are formed in the polymer network of the composite, capable of repeated, highly specific interaction with the template and the highly selective extraction of target molecules from the solution. The reaction was controlled by the added amine and by the content of oxygen-containing groups. The structure and composition of the resulting composite were proven by physicochemical methods. A study of the sorption properties of the composite showed that after acid hydrolysis, the capacity increased sharply compared to a similar composite without tuning and a composite before hydrolysis. The resulting composite can be used as a selective sorbent in the process of wastewater treatment.

Demulsification of water-in-heavy oil emulsions by oxygen-enriched non-ionic demulsifier: Synthesis, characterization and mechanisms

Separation of water-in-heavy oil (W/HO) emulsions is a critical issue in petroleum industry (especially for the thickened oils and natural bitumen) due to its high viscosity and rigid interfacial film formed by natural stabilizers (e.g., asphaltenes). Herein, two different strategies have been proposed to enhance the demulsification of the W/HO emulsions from the aspects of interfacial reconstruction and bulk oil phase property regulation. Firstly, to break the rigid interfacial film at the oil–water interface, a novel demulsifier (TJU-3, Mn: 6131 g/mol) has been successfully designed, introducing high content of carboxyl groups and ester groups to the molecules. The chemical groups, molecular structure, content of oxygen-containing groups, solubility, turbidity and phase distribution rules of TJU-3 have been instrumentally determined. It was observed that TJU-3 performed well in breaking the W/HO emulsions with faster rate (reaching 100% dehydration in less 25 min) and no “tailing phenomenon” compared with other commercial demulsifiers. Secondly, to facilitate the diffusion of demulsifer molecules from bulk oil phase to oil–water interface which promote the demulsification rate, the effect of oil viscosity on the demulsification efficiency has been investigated. Results showed that, after working with demulsifiers, when only one single method (heating or dilution at ambient conditions) was used, the dehydration rate of W/HO emulsions is limited (no more than 50%). When combining demulsifiers with diluents at slight heating conditions, a complete dehydration (∼100%) of W/HO emulsions was obtained, which was optimized at 60 ℃, 400 ppm. This synergistic effect was mainly contributed to the fact that viscosity reduction weakens the obstruction of the demulsifier diffusion and increases the average kinetic energy of the thermal movement of demulsifiers. This work would provide insights for developing new low-carbon demulsification separation method for petroleum production.

Essential Role of Forest Fires in Humic Acids Structure and Composition Alteration

Pyrogenic components of soil organic matter are practically not taken into account when assessing the implications of global climate changes on the SOM sequestration rate and its stability. In this regard, both the amount and structural stability of SOM were investigated for postpyrogenic forest–steppe environments. Mature unaffected by fire Psamment Entisols were investigated in comparison with same soil strongly affected by surface and crown fires in 2010 in Tolyatti city. This article discusses postpyrogenic succession when comparing the results of field works in 2010 with 2020. The elemental composition of humic acids as well as 13C NMR spectra were investigated for the studied humic acids. Moreover, for the first time ever, integrated indicators of HAs’ molecular composition were presented for postpyrogenic soils. The data obtained showed that there are significant changes in the structural organization of organic matter as a result of forest fires. A simultaneous decrease in the H/C and O/C atomic ratios was identified as a result of fire, which indicates a slight loss of oxygen-containing functional groups, while the aromaticity degree of molecules increases. An increase in the content of oxygen-containing groups in the HA molecules was shown for 10 years after the fires, which was accompanied by the oxidation of the HA molecule with the same increase in the aromaticity degree of the HA molecule. The HA molecules of 2020 turned out to be more resistant to environmental factors compared to analogues in 2010. As a result of fires, the aromaticity degree of HAs molecules significantly increases.

Trapa natans husk-derived carbon as a sustainable electrode material for plant microbial fuel cells

The plant microbial fuel cell (PMFC) is a novel technology that can be used to convert solar energy into electrical energy using microbes in the rhizosphere of plants. However, low power density is one of the major obstacles to the development of PMFCs. In this study, we show that the Trapa natans husk-derived carbon (TNH-GBG) is a potential sustainable electrode material for the Canna indica-based PMFCs. The results of the polarization curve measurements showed that the maximum power density of the PMFC utilizing the TNH-GBG-coated graphite felt as the electrodes could reach 55 mW m−2. This was considerably higher than that of the PMFC with pure graphite felt electrodes (22 mW m−2). The enhanced power density of the TNH-GBG was attributed to its high surface area and high content of oxygen-containing groups on the surface of carbon, which enhanced the hydrophilicity and possibly enhanced the microbial attachment, thereby reducing the activation polarization. Furthermore, when the PMFC (with TNH-GBG-coated graphite felt electrodes) was connected to an external load (1000 Ω), a power density of 20 mW m−2 was maintained for over 10 days, which is also higher than that of the PMFC with the graphite felt electrodes. The PMFC with the TNH-GBG-coated graphite felt electrodes shows a similar performance with the one with commercial activated carbon-coated graphite felt electrodes. However, the price of the TNH-GBG is only one-fifth of the commercially activated carbon. Furthermore, the TNH-based PMFC-supercapacitor system was assembled, and it demonstrated that TNH is a potential low-cost electrode material for sustainable power generation-energy storage applications.

Structure and evolution features of cutinite with different coal rank from stacking and arrangement of aromatic fringes in HRTEM

The structure and evolutionary features of cutinites isolated from the two samples of different ranks were evaluated by image analysis of aromatic fringes in high resolution transmission electron microscopy (HRTEM) combined with Photoshop and ArcGIS software. The distributions of aromatic fringes (length, orientation, curvature, segmented angle and cumulative angle) were quantified to establish the differences in stacking and spatial arrangement of the aromatic systems in the two cutinites. The bonding states of organic carbon in cutinite, derived from XPS spectra, mainly existed in the form of –CC–, followed by –C–O bonds, whereas the content of π–π bonds was the lowest. The content of oxygen-containing groups decreased and the amount of π–π bonds increased with rank. HRTEM aromatic fringe image analysis showed that short (<0.59 nm) and middle-sized fringes (<1.49 nm) in cutinite were dominant, and that the aggregated structure was mainly 1–2-ring aromatics. The preferred orientations and distribution of aromatic fringes were closely related to the stacking configurations of aromatic systems and to the rank. The larger polyaromatic clusters were observed with higher rank, and the aromatic fringes became more regular. The aromatic systems of cutinite-P (cutinite isolated from Panzhihua area) contained abundant carbon structural layers with screw dislocations, and the contents of Y-type and T-shape arrangements were lower than those of cutinite-L (cutinite isolated from Luquan area). T-shape and Y-type structures were widely distributed in the short fringes (<0.59 nm). The stacking geometry of screw dislocations was observed extensively in medium and long fringes, and the local molecular-oriented domain was isolated by short fringes. Further, the evolution of chemical structure in cutinites in terms of the distribution of orientation, curvature, and cumulative angle of aromatic fringes showed different trends. This present paper is one part of a study that seeks to establish new perspectives on the relationships between coal structure and reactivity.

Energy Feature of Air Bubble Detachment from a Low-Rank Coal Surface in the Presence of a Dodecane–Oleic Acid Collector Mixture

It has been generally proved that mixed collectors can enhance the flotation of low-rank coal (LRC). However, the inhibition effect of mixed collectors on the detachment between particles and bubbles is still unclear. In this paper, the energy feature of air bubble detachment from the LRC surface in the presence of dodecane (D), oleic acid (OA), and the mixture of dodecane and oleic acid (OA–D) was studied. The effect of collectors on the LRC surface property was analyzed using contact angle measurement, X-ray photoelectron spectroscopy, and wetting heat measurement. The force and displacement during the detachment process were measured synchronously using microforce balance. The results showed that the collector treatment increased the C–C/C–H content and decreased the content of oxygen-containing groups on the LRC surface. The synergistic effect between OA and D enabled the mixed collector to exhibit higher contact angle and wetting heat. Bubble detachment from the LRC surface can be divided into two stages: bubble stretching and bubble sliding, which corresponded to activation energy and detachment work, respectively. The activation energy and detachment work decreased in the same order of OA–D > OA > D, indicating that the mixed collector OA–D increased the energy of bubble detachment from the LRC surface and enhanced the adhesion strength. The theoretical detachment work was calculated, and the calculated results were in agreement with the measured results. This research provides a new perspective on the mechanism of LRC flotation being improved by mixed collectors.

Revealing the role of oxygen-containing functional groups on graphene oxide for the highly efficient adsorption of thorium ions

Oxygen-containing functional groups on the surface of carbon materials can promote the adsorption capacity of radioactive thorium ions (Th(IV)), but their effect on the adsorption of Th(IV) has not been systematically revealed. Herein, to elucidate the nature of oxygen-containing group-mediated Th(IV) adsorption, a series of graphene oxide nanoflakes (GONFs) with different contents of oxygen-containing groups on the surface were prepared. The experimental results showed that the high adsorption of Th(IV) not only resulted from the oxygen content, but also was related to the type of oxygen-containing functional groups on GONFs. Subsequent density functional theory (DFT) calculations revealed that the high adsorption capacity for Th(IV) originated from the oxygen-containing groups and their adjacent activated sp2 carbon atoms. More importantly, the coordination of Th(IV) with oxygen functional groups induced the aggregation of GONFs, leading to the sedimentation of GONFs, which facilitated the separation of adsorbents and enabled the GONFs to be a more practical adsorbent for Th(IV). This work deepens our understanding of the role of oxygen-containing groups on Th(IV) adsorption and provides a new strategy for the design and synthesis of high-performance surface oxygen-containing carbon-based adsorbents with practical application potential.

Impedance matching strategy boost excellent wave absorption performance of zinc-Aluminosilicate cladded short carbon fiber core-sheath structure

Excellent impedance matching and practical material design are the keys to obtaining excellent microwave absorption performance and application. In this paper, a zinc aluminosilicate (ZAS) glass-ceramic precursor was prepared by a sol-gel method, short carbon fiber (SCF) was used as the main wave absorber, and a silane coupling agent (KH-550) was used to combine the ZAS and SCF. The oxidation concentration of short carbon fibers affects the load of KH-550, which changes the concentration of oxygen-containing groups on the SCF, affecting the thickness of the ZAS coated on the SCF to adjust the impedance matching of the material. In short, through simple experimental methods and adjustment methods, we can obtain the target's absorption performance and corresponding bandwidth. Our work provides a new idea for obtaining impedance matching adjustment of high-performance carbon fiber, and glass-ceramic composite electromagnetic (EM) wave absorbing materials.

Effects of surface characteristics of wood on bonding performance of low-molar ratio urea–formaldehyde resin

ABSTRACT Low-molar ratio UF resin was used in bonding veneers of five wood species. Significantly different bonding strengths were observed among the used wood species. Much higher bonding strengths were found for cherry, sapele mahogany and black walnut, which would be attributed to their natural roughness that allows formation of more mechanical interlockings. After 60s Gliding Arc Discharge (GAD) plasma treatment of wood surface, the wet bonding performance was significantly improved for most of the wood species. The SEM images of wood surface indicated that the roughening, micrometer-scale peeling or etching effects of GAD plasma treatment would be related to the improved bonding performance. XPS characterizations showed that plasma treatment resulted in remarkable increase of O/C ratio for all wood species. Detailed analysis of C1s spectra revealed that drastic oxidation induced by plasma generated high content of oxygen-containing groups, while degradation led to exposure of more oxygen-containing components like cellulose and hemicellulose. In contrast to untreated surface, stronger interactions can be formed between highly polar wood surface and UF resin. GAD plasma appeared to be an efficient tool in both physical and chemical modifications of wood surface.

ИЗМЕНЕНИЕ СОСТАВА ПОВЕРХНОСТИ ЯЧЕИСТОГО УГЛЕРОДА ПРИ ФИЗИКО-ХИМИЧЕСКОМ МОДИФИЦИРОВАНИИ

The possibility of using both gas-phase (CO2) and liquid-phase (HNO3, H2O2) modification of cellular carbon foam with the study of changes in the content of oxygen-containing groups on its surface is shown. It has been established that when the cellular carbon foam is activated in a CO2 at a temperature of 350°C, there is no loss of mass of the initial sample, and an increase in the activation time from 1 to 3 hours leads to an increase in the number of functional groups by 11 rel.%. Liquid-phase oxidation allowed us to establish that an increase in the concentration of the oxidant, as well as the temperature and duration of the process leads to an increase in the number of functional groups on the surface.

Study of the interaction mechanism between GO/rGO and trypsin

The mechanism of GO/rGO interaction with trypsin is investigated using multiple methods. UV-Vis reveals that trypsin has a maximum absorption at 278 nm, the absorption intensity increased demonstrating GO/rGO alters the solvent environment of trypsin and exposes the aromatic chromogenic groups. ITC experiments with GO and trypsin provide a negative ΔH of -25.98 KJ mol−1and the association constant Ka of 4.829 × 10−4. The negative ΔS of -23.64 J mol−1∙K−1 is further given by the Gibbs–Helmholtz equation. Combining with the ζ potential result, the driving forces for binding include hydrogen bonding, electrostatic interaction forces and van der Waals forces. Fluorescence spectroscopy shows that GO/rGO can significantly quench the fluorescence intensities of trypsin. The equilibrium constant Kd of GO/ rGO-24h / rGO-48h is 4.41±0.07, 5.82±0.53, 7.24±0.25, respectively, which means the reduced content of oxygen-containing groups can weaken the binding forces between GO/rGO and trypsin. CD show that even low concentrations of GO/rGO affect the secondary structure of trypsin, mainly decreasing the α-helix and β-fold content while increasing the β-turn and random coil content of trypsin. Overall, GO/rGO can effectively interact with trypsin, the oxidation degree of GO/rGO can affects the combination of trypsin and further influence on protein conformation and function.

Modification of carbon sorbents by ozonation

The paper presents the results of a study of changes in the textural and physicochemical properties of the carbon sorbent surface after oxidative modification with an ozone-oxygen mixture. For the study, we used a carbon sorbent sample obtained on the basis of long-flame coal. It is shown that oxidative modification with the mixture leads to an increase in the surface area of the studied sorbent, mainly due to the growth of micro-and mesopores. In this case, according to IR spectroscopy data, an increase in the content of oxygen-containing groups on its surface is observed.

Impact of ball-milling of carbide-derived carbons on the generation of hydrogen peroxide via electroreduction of oxygen in alkaline media

Ball-milling is an effective method to decrease the size of carbide-derived carbon (CDC) grains, but milling might also affect other properties of CDC materials including but not limited to specific surface area (SSA), porosity, elemental composition and electrochemical properties. Thus, the goal of this work is to ball-mill various CDCs synthesised from silicon or titanium carbides and explore the effect of milling conditions on their physico-chemical and electrochemical properties. N 2 physisorption studies reveal that small ZrO 2 beads (0.5 mm in diameter) affect the SSA much less than bigger balls (5 mm in diameter) and the total porosity increases in the milled CDCs as compared to the initial microporous CDC materials referring to the formation of mesopores. Scanning electron microscopy (SEM) studies show that the morphology of the ground CDCs resembles that of submicron carbon powder. Slight changes regarding the total content of oxygen-containing groups on CDCs after grinding was confirmed by X-ray photoelectron spectroscopy (XPS). No significant change was observed between the activity of the initial and ball-milled CDCs towards the oxygen reduction reaction (ORR) in alkaline media by rotating ring-disc electrode (RRDE) method. The ORR on CDCs proceed via 2 + 2e − mechanism: O 2 reduction to HO 2 − followed by further electroreduction of HO 2 − to OH − . • Ball-milling with small beads (0.5 mm) have drastic impact on the CDC's morphology. • High specific surface area of CDC materials is maintained if small beads are used. • The electrocatalytic ORR activity slightly improved after ball-milling of CDCs. • Pristine and ball-milled CDCs produce high yield of HO 2 − at low overpotentials.

La and Sr Composite Oxides-modified Graphite Felt for Aqueous Organic Redox Flow Batteries

In this study, aqueous organic redox flow batteries(AORFBs) with NaCl as supporting electrolyte were investigated. In AORFBs, the chlorine evolution reaction should be retarded, not the hydrogen evolution reaction. To enhance the catalytic activity of the graphite felt(GF) electrode, the metal oxides were proposed to decorate on the GF surface. Among the loading oxides, significant enhancement of the mass transfer and reaction activity was obtained by the presence of LaSrOx nanoparticles. X-Ray photoelectron spectroscopy and contact angle measurements revealed that the content of oxygen-containing groups and the hydrophilicity were remarkably increased. After the electrode assembled in the battery, the LaSrOx/GF electrode presented huge enhancement of the battery performance, obviously increasing in the battery capacity and efficiency. At a current of 50 Am/cm2, the energy efficiency(EE) of the battery increased from 54.76% to 61.37% by the LaSrOx/GF electrode. Furthermore, the cyclability of the system tested that no obviously fading was observed after 100 cycles, signifying the excellent stability of the LaSrOx/GF electrode.

Adsorption of Volatile Organic Compounds at Medium-High Temperature Conditions by Activated Carbons

Activated carbon (AC) adsorption is an effective method for abatement of volatile organic compounds (VOCs) in coal-fired power plants. The adsorption behaviors of VOCs (toluene and chlorobenzene) for ACs (coconut shell-based AC (CSAC) and wood-based AC (WAC)) under medium-high temperature (MHT: 90–150 °C) conditions were investigated in a fixed-bed reactor. The results indicated that the adsorption capacity of VOCs was reduced with increasing temperature. CSAC had a higher adsorption capacity and adsorption rate for the two VOCs than WAC at the same adsorption temperature. The adsorption capacity of toluene was within the range of 13.9–49.9 mg/g, while that for chlorobenzene was 26–80.3 mg/g. The content of oxygen-containing groups on the AC surface was increased with acid modification and decreased with alkali modification. The adsorption capacity of AC was improved to varying degrees after chemical modification. Adsorption was mainly controlled by physical adsorption, whereas the effects of chemisorption became evident with increasing temperature. The interactions between oxygen-containing groups and VOCs were more beneficial for improving adsorption capacity than π–π interactions. The pseudofirst-order kinetic model better described the adsorption of VOCs by ACs. The MHT conditions promoted the intraparticle diffusion; lower VOC concentration resulted in the external mass transfer of AC becoming the adsorption rate-limiting step. Increasing the external surface area and micropore volume of AC and enriching the content of surface oxygen-containing groups were useful in enhancing the VOC removal efficiency.