In-depth study on the effect of oxygen-containing functional groups in pyrolysis oil by P-31 NMR

One of the major obstacles to the widespread use of pyrolysis oil is its high oxygen content, with oxygen atoms being mainly present in the hydroxyl and the carboxyl groups. Therefore, quantitative and accurate characterization of oxygen-containing functional groups is of great significance. This study employed ³¹P NMR to conduct in-depth studies on several model compounds including four kinds of alcohols and carboxylic acids. The model compounds have been investigated for stability in ³¹P NMR solution for both short storage (4 hours) and long storage (14 days), namely by in and ex situ monitoring. The experimental phenomena indicates that carboxylic hydroxyl has poor stability compared to alcohols hydroxyl group, which is reflected in the amount of alcohol compounds remaining over 90% after long-term storage. Among the carboxylic acids used in the study, aromatic acids are relatively stable. Interestingly, oxalic acid is extremely unstable and completely decomposed in the first hour, while formic acid had only a small amount left after one day of storage. Therefore, the optimum time for the preparation, storage and upgrading of the pyrolysis oil can be determined by analysis of the stability of the oxygen-containing functional groups in ³¹P NMR solution to ensure accuracy. Moreover, according to the results of the ³¹P NMR and other characterization methods, it can been seen that water was formed during the decomposition of all the model compounds. This is a report on the quantitative characterization of different oxygen-containing functional groups representing pyrolysis oil and the first study on the similarities and differences of the decomposition of carboxylic acids and alcohols in ³¹P NMR solution. The results of this in-depth investigation can provide important assistance in research that will further upgrade and apply pyrolysis oil.

Both aliphatic and carboxylic OH undergo the same decomposition pathway to form water during in situ³¹P NMR monitoring.     

Increasing the oxygen-containing functional groups of oxidized multi-walled carbon nanotubes to improve high-rate-partial-state-of-charge performance

Multi-walled carbon nanotubes (MWCNTs) with different oxygen functional groups were prepared from hot nitric acid reflux treatment. The acid-treated MWCNTs (a-MWCNTs) were introduced to negative active materials (NAMs) of lead-acid batteries (LABs) and the high-rate-partial-state-of-charge (HRPSoC) performance of the LABs was evaluated. A-MWCNTs with high quantities of carboxylic (COO⁻) and carbonyl (C O) functional groups significantly improve the lead sulfate (PbSO₄) reduction to lead (Pb) and thereby improve HRPSoC cycle life. The addition of a-MWCNTs to NAMs is helpful for the formation of larger crystals of ternary lead sulfate (3BS). The improved LABs performance is due to the formation of a sponge crisscrossed rod-like structure at the negative plate in the presence of a-MWCNTs. This unique channels structure is conducive to the diffusion of the electrolyte into the negative plate and delays the PbSO₄ accumulation during HRPSoC cycles. The HRPSoC cycle life with a-MWCNTs is significantly prolonged up to the longest cycles of 39 580 from 19 712. In conclusion, oxygen-containing groups on the a-MWCNTs showed significant influence on the curing process and forming process and then improved HRPSoC performance.

Multi-walled carbon nanotubes (MWCNTs) with different oxygen functional groups were prepared from hot nitric acid reflux treatment.     

Insight into carbon quantum dot–vesicles interactions: role of functional groups

Understanding carbon quantum dot–cell membrane interaction is essential for designing an effective nanoparticle-based drug delivery system. In this study, an attempt has been made to study the interaction involving phosphatidylcholine vesicles (PHOS VES, as model cell membrane) and four different carbon quantum dots bearing different functional groups (–COOH, –NH₂, –OH, and protein bovine serum albumin coated) using various tools such as PL behavior, surface charge on vesicles, QCM, ITC, TEM, LSV, and FTIR. From the above studies, it was observed that the –NH₂ terminating carbon dots were capable of binding strongly with the vesicles whereas other functional groups bearing carbon dots were not significantly interacting. This observation was also supported by direct visual evidence as shown by transmission electron microscopy, which shows that the polyethyleneimine carbon dot (PEICD) bearing –NH₂ functionality has greater affinity towards PHOS VES. The mechanistic insight presented in the paper indicates greater possibility of higher H-bonding, signifying better interaction between –NH₂ functionalized carbon dots and PHOS VES supported by FTIR, QCM, ITC and TEM. Moreover, the transport of neurotransmitters (which are generally amine compound) in neurons for cellular communication through synapse is only possible through vesicular platforms, showing that in our body, such interactions are already present. Such studies on the nano–bio interface will help biomedical researchers design efficient carbon-based nanomaterial as drug/gene delivery vehicles.

An interaction study at the nano–bio interface involving phosphatidylcholine vesicles (as a model cell membrane) and four different carbon dots bearing different functional groups (–COOH, –NH₂, –OH, and BSA-coated).     

Adsorption–desorption of CO2 on zeolite-Y-templated carbon at various temperatures

This study aims to investigate the adsorption–desorption of CO₂ on a micro-mesoporous zeolite-Y-templated carbon (ZTC) at various temperatures. ZTC was synthesized via sucrose impregnation, carbonization, and template removal. The adsorption–desorption of CO₂ on ZTC was performed using the gravimetric method. Results showed that the CO₂ adsorption capacity was 9.51 wt%, 5.60 wt%, and 3.47 wt%, and desorbed up to 59.83%, 69.70%, 77.5% for temperatures of 30 °C, 40 °C, and 50 °C, respectively. The adsorption process of CO₂ at temperatures of 30 °C and 40 °C follow the pseudo-second order, while at 50 °C follows intra-particle diffusion. The thermodynamic analyses indicate that the adsorption was due to physisorption.

A micro-mesoporous structure of ZTC was synthesized via an impregnation method, and the structure assisted in a faster CO₂ adsorption–desorption equilibrium.     

The synergistic effect of the PEO–PVA–PESf composite polymer electrolyte for all-solid-state lithium-ion batteries

Blending with poly(vinyl alcohol) (PVA) and poly(oxyphenylene sulfone) (PESf) has been investigated to improve the properties of a polymer electrolyte based on a poly(ethylene oxide) (PEO) matrix. The composite electrolyte shows a high ionic conductivity of 0.83 × 10⁻³ S cm⁻¹ at 60 °C due to the significant inhibition of crystallization caused by the synergistic effects of PVA and PESf. The symmetrical cell Li/CPE/Li is continuously operated for at least 200 hours at a current density of 0.1 mA cm⁻² without the enhancement in the polarization potential. In addition, the all-solid-state LiFePO₄/CPE/Li cells exhibit small hysteresis potential (about 0.10 V), good cycle stability and excellent reversible capacity (126 mA h g⁻¹ after 100 cycles).

PVA and PESf have synergistic effects for CPE, resulting in a wider electrochemical window, higher ionic conductivity and better cyclic performance.     

Effects of oxygen-containing functional groups on the synergy effect in pulsed bipolar plasma-catalytic reactions of volatile organic compounds

This study investigated the synergy effect of three high-concentration oxygenated reactants (4000 ppmv), namely 2-butanol, butanone, and ethyl acetate, in pulsed bipolar plasma-catalytic reactions using prepared La_0.7Sr_0.3MnO₃/mullite and isopentane as the catalyst and control compound, respectively. The intensity of the N I 336.62* peak of in situ optical emission spectra was used as the representative intensity to depict the behavior of plasma discharge. The results demonstrate that the variation in trends of plasma discharge with temperature for the four reactants was similar in terms of rising rates, and differences in functional groups did not significantly affect behavior during the reactions. The selected oxygenated organics were clearly more susceptible to catalysis alone and plasma catalysis than the control compound. The results indicate that the relative polarity of oxygenated reactants is a more crucial factor in plasma catalysis than their dielectric constant and ionization potential. A synergy quantitative index (Λ_X) and synergy factor (Ψ_X) were defined to characterize the synergistic behavior of plasma catalysis. The variation of Λ_X with conversion X demonstrates that plasma dissociation was dominant at low conversion rates, and catalysis was dominant at high conversion rates in the plasma-catalytic reaction. The order of Ψ_X values was opposite to that of relative polarities for the reactants. Overall, the plasma-catalytic reaction was construed as the combination of plasma dissociation and synergistic catalysis. Ψ_X was introduced into synergistic catalysis to establish a theoretical formula for the plasma-catalytic reaction. This theoretical formula was proven to be accurate by comparing experimental and theoretical results, and it successfully predicted the conversion–temperature curve of plasma catalysis.

Synergy effect of high-concentration oxygenated reactants were studied under pulsed bipolar plasma-catalytic (La_0.7Sr_0.3MnO₃/mullite) reactors, which theoretical formula was proven to be accurate, and successfully predicted the conversion–temperature curve.     

Highly efficient pollutant removal of graphitic carbon nitride by the synergistic effect of adsorption and photocatalytic degradation

Environmental remediation based on semiconducting materials offers a green solution for pollution control in water. Herein, we report a novel graphitic carbon nitride (g-C₃N₄) by one-step polycondensation of urea. The novel g-C₃N₄ material with a surface area of 114 m² g⁻¹ allowed the repetitive adsorption of the rhodamine B (RhB) dye and facilitated its complete photocatalytic degradation upon light irradiation in 20 min. This study provides new insights into the fabrication of g-C₃N₄-based materials and facilitates their potential application in the synergistic removal of harmful organic pollutants in the field of water purification.

A novel g-C₃N₄ with strong adsorption capability and efficient photocatalysis activity was prepared by heating urea through a facile method.     

The development of activated carbon from corncob for CO2 capture

The accumulation and incineration of crop waste pollutes the environment and releases a large amount of CO₂. In this study, corncob crop waste was directly activated using solid KOH in an inert atmosphere to prepare porous activated carbon (AC) to capture CO₂, and to introduce N-containing functional groups that favour CO₂ adsorption, urea was mixed with corncob and KOH to prepare N-doped AC. The physical and chemical properties of the AC were characterized, and the effects of the mass ratio of KOH and urea to corncob, the activation temperature and time as well as regeneration were investigated to explore the optimal preparation process. The pores in the AC are mainly micropores, with the specific surface area and pore volume reaching 926.07 m² g⁻¹ and 0.40 cm³ g⁻¹ for KOH-activated corncob and 1096.70 m² g⁻¹ and 0.48 cm³ g⁻¹ after N-doping; the C–O plus O–H ratio and the –NH– ratio, which favour CO₂ adsorption in N-doped AC were 6.04 and 1.92%, respectively. The maximum adsorption capacities for KOH-activated corncob before and after N-doping were 3.49 and 4.58 mmol g⁻¹, respectively, at 20 °C and remained at 3.44 and 4.52 mmol g⁻¹ after ten regenerations. The prepared corncob-based AC showed good application prospects for CO₂ capture.

The accumulation and incineration of crop waste pollutes the environment and releases a large amount of CO₂.     

The synergetic effect of a structure-engineered mesoporous SiO2–ZnO composite for doxycycline adsorption

The design and synthesis of an efficient adsorbent for antibiotics-based pollutants is challenging due to the unique physicochemical properties of antibiotics. The development of a mesoporous SiO₂–ZnO composite is a novel way to achieve excellent adsorption efficiency for doxycycline hydrochloride (DOX) in aqueous solutions due to the engineered highly open mesoporous structure and the ZnO-modified framework. Unlike the traditional method of obtaining mesoporous composites by post-synthesis techniques, the novel one-step method developed in this study is both effective and environment-friendly. The adsorption mechanism based on the novel synergetic effect between SiO₂ and ZnO was demonstrated through several experiments. SiO₂ led to the creation of a 3D open framework structure that provides sufficient space and rapid transport channels for adsorption, ensuring rapid adsorption kinetics. A higher number of active sites and enhanced affinity of the contaminants are provided by ZnO, ensuring high adsorption capacity. The mesoporous SiO₂–ZnO could be easily regenerated without a significant decrease in its adsorption efficiency. These results indicate that the developed strategy afforded a simple approach for synthesizing the novel mesoporous composites, and that mesoporous SiO₂–ZnO is a possible alternative adsorbent for the removal of DOX from wastewater.

The design and synthesis of an efficient adsorbent for antibiotics-based pollutants is challenging due to the unique physicochemical properties of antibiotics.     

Experimental and theoretical study of CO2 adsorption by activated clay using statistical physics modeling

The objective of this paper was to study CO₂ adsorption on activated clay in the framework of geological storage. The activation of clay was characterized via scanning electron microscopy, N₂ adsorption–desorption isotherms, and X-ray diffraction. The adsorption isotherms were generated at different temperatures, namely, 298 K, 323 K, and 353 K. Based on the experimental result, a new model was simulated and interpreted using a multi-layer model with two interaction energies. The physicochemical parameters that described the CO₂ adsorption process were determined by physical statistical formalism. The characteristic parameters of the CO₂ adsorption isotherm such as the number of carbon dioxide molecules per site (n), the receptor site densities (NM), and the energetic parameters were investigated. In addition, the thermodynamic functions that governed the adsorption process such as the internal energy, entropy, and Gibbs free energy were determined by a statistical physics model. Thus, the results showed that CO₂ adsorption on activated clay was spontaneous and exothermic in nature.

The objective of this paper was to study CO₂ adsorption on activated clay in the framework of geological storage.     

Enhanced photocatalytic reduction of CO2 to CO over BiOBr assisted by phenolic resin-based activated carbon spheres

Photocatalytic reduction of CO₂ using solar energy to decrease CO₂ emission is a promising clean renewable fuel production technology. Recently, Bi-based semiconductors with excellent photocatalytic activity and carbon-based carriers with large specific surface areas and strong CO₂ adsorption capacity have attracted extensive attention. In this study, activated carbon spheres (ACSs) were obtained via carbonization and steam activation of phenolic resin-based carbon spheres at 850 °C synthesized by suspension polymerization. Then, the BiOBr/ACSs sample was successfully prepared via a simple impregnation method. The as-prepared samples were characterized by XRD, SEM, EDX, DRS, PL, EIS, XPS, BET, CO₂ adsorption isotherm and CO₂-TPD. The BiOBr and BiOBr/ACSs samples exhibited high CO selectivity for photocatalytic CO₂ reduction, and BiOBr/ACSs achieved a rather higher photocatalytic activity (23.74 μmol g⁻¹ h⁻¹) than BiOBr (2.39 μmol g⁻¹ h⁻¹) under simulated sunlight irradiation. Moreover, the analysis of the obtained results indicates that in this photocatalyst system, due to their higher micropore surface area and larger micropore volume, ACSs provide enough physical adsorption sites for CO₂ adsorption, and the intrinsic structure of ACSs can offer effective electron transfer ability for a fast and efficient separation of photo-induced electron–hole pairs. Finally, a possible enhanced photocatalytic mechanism of BiOBr/ACSs was investigated and proposed. Our findings should provide new and important research ideas for the construction of highly efficient photocatalyst systems for the reduction of CO₂ to solar fuels and chemicals.

Photocatalytic reduction of CO₂ using solar energy to decrease CO₂ emission is a promising clean renewable fuel production technology.     

Synthesis of palm sheath derived-porous carbon for selective CO2 adsorption

Biomass-derived porous carbons are regarded as the most preferential adsorbents for CO₂ capture due to their well-developed textural properties, tunable porosity and low cost. Herein, novel porous carbons were facilely prepared by activation of palm sheath for the highly selective separation of CO₂ from gas mixtures. The textural features of carbon materials were characterized by the analysis of surface morphology and N₂ isotherms for textural characterization. The as-prepared carbon adsorbents possess an excellent CO₂ adsorption capacity of 3.48 mmol g⁻¹ (298 K) and 5.28 mmol g⁻¹ (273 K) at 1 bar, and outstanding IAST selectivities of CO₂/N₂, CO₂/CH₄, and CH₄/N₂ up to 32.7, 7.1 and 4.6 at 298 K and 1 bar, respectively. Also, the adsorption evaluation criteria of the vacuum swing adsorption (VSA) process, the breakthrough experiments, and the cyclic experiments have comprehensively demonstrated the palm sheath derived porous carbons as efficient adsorbents for practical applications.

Novel porous carbons were facilely prepared by activation of palm sheath for the highly selective separation of CO₂ from gas mixtures.     

Chemically activated core–shell structured IF-WS2@C nanoparticles enhance sugarcane-based carbon/epoxy nanocomposites

Ternary composites have demonstrated better capability than binary composites in enhancing the mechanical properties of the modified epoxy resins and are, therefore, currently under intensive investigation. Herein, we report a novel ternary nanocomposite prepared by filling a binary BPF (bisphenol F epoxy resin)/SCPs (sugarcane-based carbon powders) matrix with C-coated inorganic fullerene-like tungsten disulfide (IF-WS₂@C) nanoparticles, and the analysis of its interface synergetic effect using XPS/FTIR. This activated nano-carbon core–shell structure filler is considered an ideal nanofiller and shows the excellent mechanical performance of the ternary composites. XRD, IR, XPS, SEM, and TEM characterizations were applied in investigating this nanocomposite. The improvement of the thermal and mechanical properties demonstrated the enhancement effects of this nanofiller. The results show that the great improvement of the bending modulus of 39.4% increased with the addition of 0.5 wt% IF-WS₂@C nanoparticles, while 34.1% enhancement of bending strength was obtained with the addition of 0.2 wt% IF-WS₂@C nanoparticles. The hardness and thermal conductivity were also boosted up to 5.2% and 33.1% with 0.5 wt% addition, respectively. The incorporation of a chemically activated coating may provide a novel means for improving graphite crystallization, which could somehow expand the potential application of IF-WS₂@C nanoparticles.

Schematic diagram and typical curing mechanism of epoxy resins and the unique interactions of the IF-WS₂@C nanoparticles introduced into the matrix.     

Preparation of low carbon olefins on a core–shell K–Fe5C2@ZSM-5 catalyst by Fischer–Tropsch synthesis

In this study, a core–shell catalyst based on Fe₅C₂@ZSM-5 (ZSM-5 capped Fe₅C₂ as active phase) is prepared by the coating-carbonization method for Fischer–Tropsch synthesis (FTS). Further, the designed ZSM-5 zeolites are utilized to screen the low carbon hydrocarbons from the products generated on the iron carbide active centre, and for catalytic disassembly of the long-chain hydrocarbons into low carbon olefins. Prior to utilization, the physical–chemical properties of the prepared catalysts are systematically characterized by various techniques of X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM) observations, in addition to the effects of coating-carbonization, molecular sieve coating amount, and K-doping on core–shell iron-based catalysts. Next, the performance of Fischer–Tropsch synthesis is investigated in a micro-fixed bed reactor. The results manifest that, comparing with Fe₅C₂ and a supported Fe/ZSM-5 catalyst prepared by the traditional impregnation method, the core–shell Fe₅C₂@ZSM-5 catalysts show higher CO conversion rate, reaction activity and selectivity to low-carbon olefins. Comparatively, the Fe₅C₂@ZSM-5C catalyst prepared by carbonization after the coating method exhibited more surface area, smaller average pore size, and more reactive active sites, resulting in the improvement of screening of high carbon hydrocarbons and the enhancement of selectivity to low carbon olefins, in comparison to those prepared by the carbonization-coating method. In conclusion, the K-doping catalyst had significantly improved the reactive activity of the core–shell Fe₅C₂@ZSM-5 catalyst and the selectivity to low carbon olefins, while the CO conversion on K–Fe₅C₂@ZSM-20C still remained good.

In this study, a core–shell catalyst based on Fe₅C₂@ZSM-5 (ZSM-5 capped Fe₅C₂ as active phase) is prepared by the coating-carbonization method for Fischer–Tropsch synthesis (FTS).     

Influence of cerium doping on Cu–Ni/activated carbon low-temperature CO-SCR denitration catalysts

In this study, to evaluate the effects of two methods for activation of nitric acid, air thermal oxidation and Ce doping were applied to a Cu–Ni/activated carbon (AC) low-temperature CO-SCR denitration catalyst. The Cu–Ni–Ce/AC_0,1 catalyst was prepared using the ultrasonic equal volume impregnation method. The physical and chemical structures of Cu–Ni–Ce/AC_0,1 were studied using scanning electron microscopy, Brunauer–Emmett–Teller analysis, Fourier-transform infrared spectroscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, CO-temperature programmed desorption (TPD) and NO-TPD characterisation techniques. It was found that the denitration efficiency of 6Cu–4Ni–5Ce/AC₁ can reach 99.8% at a denitration temperature of 150 °C, a GHSV of 30 000 h⁻¹ and 5% O₂. Although the specific surface area of the AC activated by nitric acid was slightly lower than that activated by air thermal oxidation, the pore structure of the AC activated by nitric acid was more developed, and the number of acidic oxygen-containing functional groups was significantly increased. Ce metal ions were inserted into the graphite microcrystalline structure of AC, splitting it into smaller graphene fragments, whereby the dispersibility of Cu and Ni was improved. In addition, many reaction units were formed on the catalyst surface, which could adsorb more CO and NO reaction gases. With the increase in Ce doping, the relative proportions of Cu²⁺/Cuⁿ⁺, Ni³⁺/Niⁿ⁺ and surface adsorbed oxygen (Oα) in the Cu–Ni–Ce/AC_0,1 catalyst increased. In addition, after the introduction of Ce into Cu–Ni/AC, the amount of weak and medium acids significantly increased. This may be due to the Ce species or its influence on the Cu/Ni species. Further, the active sites of the acid were more exposed. According to the results of the study, a composite metal oxide CO-SCR denitration mechanism is proposed. Through the oxidation–reduction reaction between the metals, the reaction gas of CO and NO is adsorbed and the incoming O₂ is converted into (Oα), which promotes the conversion of NO into NO₂. The CO-SCR reaction is accelerated, and the rate of low-temperature denitration was increased. Overall, the results of this study will provide theoretical support for the research and development of low-temperature denitration catalysts for sintering flue gas in iron and steel enterprises.

In the process of denitrification, the reaction between NO and CO (NO + CO → N₂ + CO₂) occurs. There will be a redox reaction between copper, nickel and cerium (Cu²⁺ + Ce³⁺ → Cu⁺ + Ce⁴⁺, Ni³⁺ + Ce³⁺ → Ni²⁺ + Ce⁴⁺).     

Preparation and photocatalytic activity characterization of activated carbon fiber–BiVO4 composites

Herein, we describe the hydrothermal immobilization of BiVO₄ on activated carbon fibers (ACFs) and characterize the obtained composite by several instrumental techniques, using Reactive Black KN-B (RB5) as a model pollutant for photocatalytic performance evaluation and establishing the experimental conditions yielding maximal photocatalytic activity. The photocatalytic degradation of RB5 is well fitted by a first-order kinetic model, and the good cycling stability and durability of BiVO₄@ACFs highlight the potential applicability of the proposed composite. The enhanced photocatalytic activity of BiVO₄@ACFs compared to those of BiVO₄ and ACFs individually was mechanistically rationalized, and the suggested mechanism was verified by ultraviolet-visible spectroscopy, attenuated total reflectance Fourier-transform infrared spectroscopy, and RB5 degradation experiments. Thus, this work contributes to the development of BiVO₄@ACF composites as effective photocatalysts for environmental remediation applications.

Herein, we describe the hydrothermal immobilization of BiVO₄ on activated carbon fibers, using Reactive Black KN-B photocatalytic performance evaluation and establishing the experimental conditions yielding maximalphotocatalytic activity.     

活性炭血液灌流对有机磷农药敌敌畏和解毒药阿托品的作用

目的评估活性炭血液灌流对有机磷农药敌敌畏和解毒药阿托品的作用。方法在人血样(由解放军307医院血库提供的正常人血样)中加入敌敌畏和阿托品后,分成空白对照组和血液灌流组,观察灌流前后血中敌敌畏浓度和阿托品浓度以及血清中胆碱酯酶活力的变化。结果活性炭血液灌流中敌敌畏和阿托品的吸附率分别为(0.98±0.05)%和(0.68±0.01)%。在混合吸附试验中,吸附后的阿托品和敌敌畏之比较吸附前浓度之比增加。同时,吸附后假性胆碱酯酶活力比吸附前增长了近3倍。结论虽然在体外人血中活性炭血液灌流对人血中敌敌畏的吸附率较低(与空白组比较,P>0.05),但大大提高了血清中胆碱酯酶活力,同时提高了血中阿托品和敌敌畏的浓度之比,从而更易到达阿托品化。     

Insight into the synergistic effect on adsorption for Cr(vi) by a polypyrrole-based composite

Polypyrrole-based (PPy) composite are promising candidates for the treatment of water pollution. Adsorption selectivity as well as a large adsorption capacity are two key factors for treating wastewater containing multiple ions. The structure and morphology of the prepared composites were characterized by the FT-IR, XRD and SEM examinations. The results indicate that the Fe₃O₄ and PPy nanosphere coats attapulgite (ATP) closely and evenly. Herein, a novel Fe₃O₄ and ATP doped three-dimensional network structure PPy/Fe₃O₄/ATP composite was demonstrated as an excellent adsorbent to effectively remove Cr(vi). The as-synthesized PPy/Fe₃O₄/ATP composite is suitable for Cr(vi) adsorption in a wide pH range (pH 2–6). Up to a 96.44% removal rate was found with 400 mg L⁻¹ Cr(vi) aqueous solution in 30 min for 0.2 g PPy/Fe₃O₄/ATP adsorbent. Adsorption results showed that Cr(vi) removal efficiency by PPy/Fe₃O₄/ATP decreased with an increase in pH. The removal rate of Cr(vi) had already reached 93.63% in 15 min contact time. Co-existing ions studies exhibit inorganic oxyacid anion and transition metal cation showed negative effects on Cr(vi) removal rate. A chemical rather than a physical adsorption occurred for these adsorbents as revealed by a pseudo-second-order kinetic study. The results of the adsorption isotherms showed that the adsorption process was similar to the Langmuir isotherm adsorption. Furthermore, the PPy/Fe₃O₄/ATP composite exhibited a high stability for Cr(vi) adsorption during recycling tests process. This work may provide some useful guidelines for designing adsorbents with selectivity toward specific heavy metal ions.

Polypyrrole-based (PPy) composite are promising candidates for the treatment of water pollution.     

Simultaneous adsorption of SO2 and CO2 in an Ni(bdc)(ted)0.5 metal–organic framework

The metal–organic framework Ni(bdc)(ted)_0.5 is a promising material for simultaneous capture of harmful gases such as SO₂ and CO₂. We found that SO₂ performs much better than CO₂ during adsorption, and the lack of physical insight was clarified through detailed analyses of the electronic structures obtained from density functional theory calculations. Our results showed that strong interactions of the d band of Ni atoms with the valence states (2n, 3n, and 4n) of SO₂ but almost not with those of CO₂ are the main reasons. Our finding is useful for the rational design of new metal–organic frameworks with suitable interactions for the simultaneous capture of not only SO₂ and CO₂ but also other gases.

SO₂ performs much better than CO₂ during co-adsorption due to the d-band of Ni atoms.     

The synergistic effect of carbon coating and CNTs compositing on the hard carbon anode for sodium ion batteries

In this work, mesoporous hard carbon materials were synthesized and modified by compositing a carbon coating and carbon nanotubes (CNTs), reducing the surface area and improving the conductivities without changing the microstructures of the anodes, which enhances the coulombic efficiencies and rate performances of sodium-ion batteries (SIBs).

The synergistic effect of surface carbon coating and CNT compositing on mesoporous hard carbon was investigated. The sample showed excellent cyclic and rate performances, suggesting a highly efficient and easy scale-up approach to elevate hard carbons as anodes for SIBs.