Search

Photocatalytic technology assisted via peroxymonosulfate (PMS) has good potential in water treatment. In this study, the Co3O4/Bi2WO6 composite was constructed via an in-situ calcination process and used to activate PMS for the degradation of ciprofloxacin (CIP) under visible light irradiation. The obtained 5 wt% Co3O4/Bi2WO6(CBWO-2) can highly effectively remove 86.2% CIP within 5 min visible light irradiation in presence of PMS. The excellent degradation performance of Co3O4/Bi2WO6/PMS system can be attributed to the synergistic effect between p-n heterojunction and PMS activation. The conduction band and valence band deviation between Co3O4 and Bi2WO6 were calculated by XPS techniques. Besides, DFT calculations were performed to further confirm the internal structure between Co3O4 and Bi2WO6. This work not only provides an approach to fabricate heterostructures but also indicated that Co3O4/Bi2WO6/PMS/Vis system is a potential environment remediation alternative for the efficient removal of recalcitrant organic compounds from wastewaters.

Two silica films -immobilized imidazolium-based ionic liquids (TMICl @silica films) were prepared, characterized and utilized as efficient catalysts for the benzoin reaction. Combined characterization results from FT-IR, elemental analysis, N2 adsorption–desorption isotherms and SEM, suggested that the imidazolium-based ionic liquids were successfully immobilized on the silica films. Moreover, the catalytic performance tests demonstrated that silica films immobilized imidazolium-based ionic liquids (ILs) exhibited excellent activity for the benzoin reactions of aromatic aldehydes. The influence of catalyst concentration, temperature and reaction duration on the catalytic activity were investigated by employing 0.7TMICl @silica film(catalyst C) as the catalyst. The results also showed that the benzoin condensations of aromatic aldehydes could give desired products with satisfactory yields under the optimized conditions. Additionally, the catalyst can be effortlessly separated by filtration and reused more than five times without significant loss of activity.

In this work, a novel composite catalyst, consisting of palladium (Pd), non-metallic phosphorus (P) and graphene (GE) has been successfully prepared by a facile sodium borohydride (NaBH4) reduction method and investigated as a catalyst for ethylene glycol oxidation reaction (EGOR) in alkaline media. Transmission electron microscopy (TEM) images exhibit that PdP nanoparticles (NPs) are evenly dispersed on the GE surface. X-ray photoelectron spectroscopy (XPS) measurement reveals that P could modify the electronic structure of Pd and a stronger electronic interaction exists between them. Electrochemical tests demonstrate that the as-prepared Pd-P/GE catalyst displays higher electrocatalytic performance and better electrochemical stability toward EGOR in comparison with the monometallic Pd catalyst (Pd/GE), with the best performance observed for the PdP(1:1)/GE catalyst. All results suggest that the introduction of non-metallic P is indeed a useful way to enhance the electrocatalytic performance of Pd, which is expected to shed some light on the design of catalysts containing non-metal P or even other nonmetals to accelerate the commercialization of fuel cells.

Two polar monomers, Trimellitic anhydride and o-phthalic anhydride, are employed to copolymerize with the non-porous gel-type chloromethylated poly(styrene-divinylbenzene) (NP-CLPs), and synthesized two polar-modified hyper-cross-lined resins. The resins were efficient for adsorption of o-tolylthiourea, and possessed the largest equilibrium capacity (221.2 mg/g for TMAMR, and 206.7 mg/g for PAMR). The influences of adsorption temperature, solution pH, and salt content of the solution were studied by the static adsorption method. The Freundlich and Langmuir isotherm model were used to fit equilibrium data for all investigative temperatures (288–318 K). The Langmuir model was better than the Freundlich model at 288 K; however, with the increasing temperature the Freundlich and Langmuir models could all well describe the isotherm data. The thermodynamic parameters (ΔH0, ΔS0, and ΔG0) showed that the adsorption of o-tolylthiourea was feasible, exothermic, and spontaneous from 288 K to 318 K. The kinetic data were fitted by pseudo-first order, pseudo-second order, and intraparticle diffusion equations. Differences in adsorption of o-tolylthiourea between TMAMR and PAMR resins were interpreted by the frontier orbital energy level difference between resins and o-tolylthiourea calculated with the semi-empirical method AM1.

Herein a series of chemically modified hyper-crosslinked resins were prepared and the four resins had been employed to remove 3-Aminoacetanilide from aqueous solution. Pore size and BET specific surface area of the four resins were improved by characterization, and specific surface area size was SAMR > PRLMR > TAMR > IDLMR. The results showed that Freundlich model could fit the adsorption isotherms better than Tempkin and Langmuir equations. The adsorption process about 3-aminoacetanilide on the hyper-crosslinked resin was mainly physisorption, and the chemisorption was weak. Pseudo-second-order rate model fitted more suitable for the kinetic data and the pseudo-second-order constants suggested that the SAMR was more effective for the adsorption. Thermodynamic studies have shown that the adsorption processes were spontaneous and endothermic. Four resins exhibited maximum qe values at pH 8˜9. Column sorption experiment demonstrated that SAMR was a reliable adsorbent for the removal of 3-Aminoacetanilide in aqueous solutions and 10% (w/w) hydrochloric acid could desorb the 3-Aminoacetanilide efficiently.

The aqueous solubilities of allopurinol in some choline chloride (ChCl) based deep eutectic solvents (DESs) with urea, glycerol, citric acid and glycol as neoteric green solvents were measured by the shake-flask method at T = (293.15–333.15) K under atmospheric pressure p = 101.1 kPa. The solubility in these solvents increased more than approximately 27.8-fold for ChCl/urea system, 45.6-fold for ChCl/glycerol system, 31-fold for ChCl/glycol system and 56-fold for ChCl/citric acid system with increasing the weight fraction of DESs. The solubility data was accurately correlated by the λh equation and modified Apelblat equation. The largest percentage of relative average deviation was 1.49 × 10−2, and the maximum value of root-mean-square deviation was 2.43 × 10−5. Also, in order to describe the thermodynamic behaviour of allopurinol in the aqueous DESs solutions, the transfer properties were derived. The negative Gibbs free energy (ΔtrGo) and enthalpy (ΔtrHo) values indicated that the transfer of allopurinol from neat water to aqueous DESs solutions was spontaneous and energetically favourable. Additionally, the ΔtrGo and ΔtrHo values decreased with the increase in the DESs concentrations, indicating that solubilization was more favourable with the increase in the DESs concentrations. In particular, the ΔtrGo values considerably decreased for ChCl/citric acid compared to ChCl/urea, ChCl/glycerol and ChCl/glycol mixtures. ChCl/citric acid is an effective additive for improving the solubility of allopurinol. Furthermore, the excess enthalpy of solution was obtained according to the λh equation.

Fe-Ni bimetallic nanoparticles supported on CNTs (Fe-Ni/CNTs) were synthesized, characterized, and applied for removal of 2,4-dichlorophenol (2,4-DCP) in aqueous solution. The removal performance was enhanced drastically on Fe-Ni/CNTs with respect to monometallic Fe/CNTs. The synergistic effect between Fe-Ni nanoparticles and CNTs has been studied in detail. The research results indicated that the doping of Ni played an important role in promoting the catalytic degradation of 2,4-DCP. And the presence of CNTs not only could effectively reduce the aggregation of nanoparticles but also facilitate the mass transfer of 2,4-DCP and the formation of active atomic hydrogen during the catalytic process. In addition, the removal kinetics of 2,4-DCP by Fe-Ni/CNTs were in agreement with a pseudo-first-order model, and the rate constants were dependent on a number of factors including the initial concentration of 2,4-DCP, the dosage of Fe-Ni/CNTs, pH value of the solution, and doping amount of Ni. The degradation mechanism involved the adsorption by CNTs and catalytic reduction by Fe under the stimulating of Ni, and the preferred dechlorination followed the order of para-Cl > ortho-Cl. The study confirmed that Fe-Ni/CNTs had a potential to be a promising catalytic material for removal of chlorophenol and had a great prospect for practical application.

Organic-palygorskite (OP) supported Pd/Fe nanoparticles composite (OP-Pd/Fe) was prepared by stepwise reduction method. The removal capacity of 4,4ʹ-dibrominated diphenyl ether (BDE15) by OP-Pd/Fe was compared with other various materials. For better understanding the possible mechanism, the synthesized and reacted OP-Pd/Fe materials were characterized by TEM, SEM, XRD, and XPS, respectively. The effects of major influencing parameters on the degradation of BDE15 were also studied. Benefit from the synergistic effect of the carrier and bimetallic nanoparticles, BDE15 could be completely debrominated into diphenyl ether (DE) under suitable conditions. A two-stage adsorption/debromination removal mechanism was proposed. The degradation of BDE15 with OP-Pd/Fe was mainly stepwise debromination reaction, and hydrogen transfer mode was assumed as the dominated debromination mechanism. The removal process fitted well to the pseudo first-order kinetic equation. The observed rate constants increased with increasing Pd loading and OP-Pd/Fe dosage, while decreased with increasing initial BDE15 concentration, the tetrahydrofuran/water ratio, and the initial pH of the solution. The work provides a new approach for the treatment of PBDEs pollution.

A series of functional hyper-cross-linked resins were successfully synthesized by incorporating anhydride, sulfoacid and menthanone groups into post-cross-linked polymer. They were evaluated for adsorption of 2-amino-4-methylbenzothiazole (2A4MBT) from aqueous solution. The five resins were efficient for adsorption of 2A4MBT from aqueous solution. The adsorption process includes both physical adsorption and irreversible chemical adsorption. The absolute value of adsorption enthalpy had an order of PRLMR (3.24 kJ mol−1)

The non-radical oxidation processes of persulfate activation by carbon materials have shown great potential for industrial and saline wastewater treatment. Recently, metal-organic frameworks (MOFs) as an emerging precursor have been widely used for fabricating functional carbon materials. Herein, we reported ZIF-8 derived defect-rich nitrogen-doped carbon (ZCNs) via NaCl-assisted pyrolysis for efficient non-radical activation of peroxydisulfate to degrade rhodamine B (RB). All samples exhibited excellent catalytic activity, and ZCN-900 (pyrolyzed at 900 °C) was found to be the most active, able to degrade 96 % of RB quickly within 10 min. Quenching tests and electron paramagnetic resonance (EPR) analyses suggested that the singlet oxygen (1O2) dominated the degradation process by a non-radical pathway. Furthermore, the effect of anions and water quality on RB oxidation were investigated, and ZCN-900/PDS system showed great resistance to the anions and natural organic matters (NOM). This work may provide a significant addition to MOF-based functional materials for environmental remediation based on the results above.

Semiconductor photocatalysis technology is a promising method for hydrogen production and water pollution treatment. Here, the SnIn4S8/CeO2 (SISC) composites were fabricated by a stirring and calcination method, and the mass ratio of SnIn4S8 to CeO2 was optimized. The 50 wt% SISC heterojunction photocatalyst has the highest visible light catalytic activity. The degradation rate of hexavalent chromium (Cr (VI)) is 98.8% in 75 min of light irradiation, which is 2.48 times that of pure CeO2. Besides, the 50 wt% SISC composite photocatalyst also has the highest photocatalytic hydrogen production efficiency (0.6193 mmol g−1 h−1), which exhibits a higher photocatalytic activity than pure CeO2 and SnIn4S8. The enhanced photocatalytic performance can be attributed to the Z-scheme heterojunction structure between CeO2 and SnIn4S8, which can effectively separate and transfer photo-generated charges, thereby reducing the recombination of photo-generated carriers. We hope this work can provide ideas for constructing Z-scheme heterojunction structures and improving photocatalytic activity under visible light.

The aim of this study was to reveal the mechanisms on how biochar reduces bioaccumulation of polycyclic aromatic hydrocarbons (PAHs) in tuberous vegetables. Corn straw-derived biochar pyrolyzed at 300°C (CB300) or bamboo-derived biochar pyrolyzed at 700°C (BB700) was amended into PAH-contaminated soil planted with carrot (Daucus carota L.). After 150days, 2% CB300 or 2% BB700 amendments significantly reduced the bioaccumulation of PAHs in carrot root (p

Traditional exhaustive extraction methods often overestimate the risk of polycyclic aromatic hydrocarbon (PAH) bioaccessibility to biota. Therefore, reliable assessment methods need to be established. In this study, a composite extraction with hydroxypropyl-β-cyclodextrin (HPCD) and three low-molecular-weight organic acids, oxalic acid (OA), malic acid (MA), and citric acid (CA), was used to predict the PAH bioaccessibility to earthworms, subjecting to two soils (red soil and yellow soil) spiked with selected PAHs, phenanthrene, pyrene, chrysene, benzo(a)anthracene, benzo(b)fluoranthene, benzo(k)fluoranthene, and benzo(a)pyrene. For both soils, concentrations of PAHs by composite extraction using HPCD-OA (R2 = 0.89–0.92, slope = 1.89–2.03; n = 35), HPCD-MA (R2 = 0.92–0.96, slope = 1.43–1.67; n = 35), and HPCD-CA (R2 = 0.92–0.96, slope = 1.26–1.56; n = 35) were significantly correlated with PAH accumulation in the Eisenia fetida earthworms. Moreover, the HPCD-CA- and HPCD-MA-extracted PAH concentrations were closer to the earthworm-accumulated PAH concentration than the extraction using just HPCD. The results indicated that the composite extraction could improve the prediction of PAH bioaccessibility, and therefore can serve as a reliable chemical method to predict PAH bioaccessibility to earthworms in contaminated soils.

Photocatalytic technology assisted via peroxymonosulfate (PMS) has good potential in water treatment. In the study, the Co3O4/Bi2MoO6 p-n heterostructure photocatalyst was prepared via an in-situ calcination process and was applied to activate PMS for degrading norfloxacin (NFA) under visible light irradiation. The obtained 5 wt% Co3O4/Bi2MoO6/PMS can effectively remove 87.68% of NFA within 30 min under visible light irradiation. The excellent degradation performance of Co3O4/Bi2MoO6/PMS system can be attributed to the synergistic effect between p-n heterojunction and PMS activation. The conduction band and valence band deviation between Co3O4 and Bi2MoO6 were calculated according to XPS techniques, and the results of anion interference experiments and circulation experiments revealed that the Co3O4/Bi2MoO6/PMS system has good stability. Besides, the possible degradation pathways of NFA were proposed and DFT calculations were performed to further confirm the internal structure between Co3O4 and Bi2MoO6. This work provides a new idea and a new catalyst for the degradation of organic pollution in water.

It is of great significance to develop a simple, cheap, and efficient catalyst preparation method for the development of fuel cells. Despite considerable developmental efforts have been substantial, progress has been underwhelming. To this end, a simple one-pot approach has been designed for the fabrication of Pd–Ag alloy networks (NWs) catalysts using sodium borohydride (NaBH4) as the reducing agent and cetyltrimethylammonium bromide (CTAB) as the surfactant. The electrochemical results reveal that the addition of Ag not only reduces Pd consumption but also enhances the catalytic properties of the electrocatalysts. Particularly, the current density of a Pd2Ag1 NWs-catalyzed ethylene glycol electro-oxidation reaches 1902.9 mA mg−1, which is 1.40 times higher than that for commercial Pd/C. The catalyst’s impressive performance could be attributed to its distinctive network-like structure and the promoting effect of Ag, which is in agreement with the bi-functional mechanism and a d-band electronic structure. This work is expected to have an impact for optimization of the design of high-performance Pd-based catalysts for applications in fuel cells and in the related fields.

An Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed along with other observation instruments to measure the characteristics of PM1 (particulate matter with a vacuum aerodynamic diameter of ≤1μm) during the biomass burning period (October 1 to 27; BBP) and the coal combustion period (December 10 to 31; CCP) in Beijing in 2014. The average PM1 mass concentrations during the BBP and CCP were 82.3 and 37.5μgm(-3), respectively. Nitrate, ammonium and other pollutants emitted by the burning processes, especially coal combustion, increased significantly in association with increased pollution levels. Positive matrix factorization (PMF) was applied to a unified high-resolution mass spectra database of organic species with NO(+) and NO2(+) ions to discover the relationships between organic and inorganic species. One inorganic factor was identified in both periods, and another five and four distinct organic factors were identified in the BBP and CCP, respectively. Secondary organic aerosols (SOAs) accounted for 55% of the total organic aerosols (OAs) during the BBP, which is higher than the proportion during the CCP (oxygenated OA, 40%). The organic nitrate and inorganic nitrate were first successfully separated through the PMF analysis based on the HR-ToF-AMS observations in Beijing, and organic nitrate components accounted for 21% and 18% of the total nitrate mass during the BBP and CCP, respectively. Although the PM1 mass concentration during the CCP was much lower than in the BBP, the average concentration of polycyclic aromatic hydrocarbons (PAHs) during the CCP (107.3±171.6ngm(-3)) was ~5 times higher than that in the BBP (21.9±21.7ngm(-3)).

Herein m-phenylenediamine was employed as the introduced polar groups reagent to prepare a novel amino-modified hyper-cross-linked resin (MPDAMR) by two successive Friedel–Crafts reactions. The adsorption capacities of MPDAMR for two chloroanilines in aqueous solution were compared with two commercial resins (macroporous resin XAD-4 and hyper-cross-linked resin NDA150) and its precursor (post-cross-linked resin, PCLR). MPDAMR possessed high BET surface area (1040.7 m2/g), abundant micropores, and plentiful amino groups. The adsorption efficiencies of 4-chloroaniline (4-CA) and 2,4-dichloroaniline (2,4-DCA) by MPDAMR were 78.7% and 97.8%, respectively, which were much higher than that of XAD-4, NDA150, and PCLR. The excellent adsorption capacity of MPDAMR for chloroanilines was attributed to its high surface area, abundant micropores, primary amine driven enhanced polarity, and π–π stacking interactions. Pseudo first-order kinetics equation and Freundlich equation were capable of explaining the adsorption process of chloroanilines onto MPDAMR. Both the intraparticle diffusion and film diffusion were rate-controlling steps. The thermodynamics results attested that the adsorption of chloroanilines was a spontaneous exothermic process. The saturated adsorption capacities of MPDAMR for 4-CA and 2,4-DCA were 213.8 mg/g and 278.4 mg/g dry resin, respectively. Additionally, MPDAMR had good regenerated adsorption capacity after five adsorption-desorption cycles. Thus, MPDAMR was a potential adsorbent used to remove chloroaniline compounds from industrial effluent.

The development of simple and effective approaches for the synthesis of bimetallic oxide heterojunction photocatalyst which are used to activate peroxymonosulfate (PMS) under visible-light-driven is highly feasible but remains a great challenge. In this work, the Co3O4/CeO2 composite was prepared by a facile chemical reaction, followed by annealing in a muffle furnace and then applied to activate PMS for ciprofloxacin (CIP) degradation. Various characterizations confirmed the formation of p-n heterojunction between Co3O4 and CeO2. Meanwhile, the 5 wt% Co3O4/CeO2/PMS composite showed highest degradation rate of CIP (87.8%) under visible light irradiation. The obtained Co3O4/CeO2/PMS system still exhibited a good catalytic performance in presence of different anion. Besides, the active radical h+, OH, O2−, and SO4− are involved in CIP degradation. The excellent degradation performance can be interpreted as the synergistic effect between Co3O4/CeO2 heterojunction photocatalyst and PMS activation. Moreover, the energy band structure and valence band deviation of Co3O4/CeO2 p-n heterogeneous junction were confirmed. This work would give a reference for combining the photocatalyst and activation of PMS under visible light for further removal of pollutants.

Over the past years, photocatalytic technology has exhibited a great potential in treating wastewater, splitting water to hydrogen and reducing CO2 to fuel. Among, more and more researchers attempt to design AgI based heterojunction photocatalytic systems for developing novel photocatalysts with excellent performance. However, a review about AgI based photocatalytic systems is still absent. Herein, two the charge carrier transfer processes in Type II and Z-scheme heterojunction photocatalytic system were firstly presented systemically. Then the recent developments of AgI based different heterojunction photocatalytic systems were summarized. The photocatalysts commonly modified by AgI are classified, and the role of AgI in different heterojunction photocatalytic systems is analyzed in detail. Additionally, the application of AgI based composites in environmental restoration and energy conversion field are presented including degradation of pollutants, photocatalytic hydrogen generation, carbon dioxide reduction and disinfection. Meanwhile, the typical mechanism of these photocatalytic reactions based on AgI composites is also described in detail. Finally, unresolved challenges and potential applications of AgI based composites are presented for guiding the direction for future development.

In this study, the adsorption performances of PRLMR and IDLMR for methyl anthranilate from aqueous solution were studied by adsorption thermodynamics and adsorption kinetics. The effect of methanol addition on the adsorption was also investigated. The results indicated that the modified resins possessed good adsorption capacities for methyl anthranilate, while IDLMR possessed much larger adsorption capacity for the adsorbate. The equilibrium data were correlated by both Langmuir and Freundlich models. The adsorption capacity decreased as 1% methanol added into the methyl anthranilate solution. The kinetic experiments showed that the adsorption process was in accordance with the pseudo-first-order rate equation, and the value of pseudo-first-order rate constant k at 303K was larger than that at 288K, which suggested that the IDLMR possessed much faster adsorption rate for methyl anthranilate from aqueous solution at 303K.

For the first time, the dechlorination of 2,6-dichlorophenol (2,6-DCP) by carbon nanotubes supported Fe/Ni nanoparticles (CNTs-Fe/Ni) was studied to explore the practicability of environmental remediation. Removal capacity of CNTs-Fe/Ni for 2,6-DCP was enhanced obviously compared to Fe/Ni due to reduced aggregation of Fe/Ni nanoparticles.The removal efficiency increased as the increase of CNTs-Fe/Ni dosage and Ni loading, whereas it decreased as the increase of 2,6-DCP concentration. Weak acidic condition was considered to be advantageous to 2,6-DCP dechlorination. The dechlorination kinetics results suggested that the 2,6-DCP removal by CNTs-Fe/Ni accorded with pseudo-first-order equation. Moreover, carbon nanotubes as support accelerated the mass transfer of 2,6-DCP from solution to catalyst surface and promoted the formation of atomic hydrogen, which also led to an enhancement of reactivity of CNTs-Fe/Ni on removing 2,6-DCP.

Background Clay minerals especially organoclays modified by the introduction of organic molecules into the mineral structure show much promise for environmental remediation applications. Application of organic attapulgite (O-APG) and organic montmorillonite (O-MMT) as soil amendments to bind polychlorinated biphenyl (PCB) in contaminated soils and observe PCBs accumulated in the ryegrass shoots and roots was investigated. Results Pot experiments in greenhouse indicated that organoclays could significantly fix the PCB in soils and reduce its contents in ryegrass shoots and roots. Compared with the control, the migration of concentrations of PCB into the environment in contaminated soils is reduced by about 28.5 and 44.1%, and concentrations of PCB in ryegrass roots and shoots were reduced within the range from 57.0 to 63.0% and 49.6 to 56.5%, respectively, through addition of 6% organic attapulgite and montmorillonite. There was a negative correlation between the accumulation of PCB in ryegrass and the amount of organoclay addition. The accumulations of PCB in ryegrass roots were significantly higher than those in the ryegrass shoots. Conclusions The two organoclays had been proved effective as environmental amendments for reducing the mobility and bioavailability of PCB in contaminated soils. The results of this study provided an efficient method for the remediation of PCB contaminated soils.

How soil carbon is stabilized during centuries of cultivation and how this would be influenced by land use largely remain unclear. Here the relative role of physical and chemical stabilization mechanisms in agricultural soil organic carbon (SOC) accumulation were studied by fractionation of paddy/upland cropland soils along a 500-year soil chronosequence created by intermittent reclamation of estuarine wetlands. In unreclaimed wetlands, about 50% of SOC was chemically-stabilized by binding to Fe/Al oxyhydrates (mainly amorphous Fe) and 30% by unknown forms of chemical association with silt/clay particles. Physical stabilization of SOC by soil aggregation was negligible in wetlands. After conversion of wetlands to croplands, SOC rapidly declined within the first 16 years and then recovered slowly with cultivation time. Chemical mechanisms still dominated SOC stabilization processes during 500 years of cultivation, but the contribution of Fe/Al-bound and Ca-bound carbon to total SOC decreased with time. The contribution of physically stabilized carbon (i.e. microaggregate-occluded particulate organic carbon, iPOM) to SOC kept around 16% in croplands even when microaggregate contents increased from 8.83% to 30.52% between 16 and 500 years. The iPOM fraction was not closely related to microaggregate formation but to free coarse particulate organic matter, a carbon fraction indicative of inputs of plant materials. Consistently higher SOC density in paddy soils than in upland soils was observed along the chronosequence, which could be accounted for by higher contents of physical and chemical carbon fractions in paddy fields. The higher physically-stabilized carbon of paddy soils probably resulted from larger stubble return rather than from stronger soil aggregation given similar contents of microaggregates between the two cropland types. Notably, in both paddy and upland soils, carbon concentrations of intra-microaggregate silt/clay particles were consistently higher than those of free silt/clay particles. An implication was that despite the small proportion (

Design of high performance and low cost electrocatalysts for the oxidation of small organic molecules remains a great challenge for the practical application of direct fuel cells. Herein, a novel composite catalyst composed of PdAu nanoparticles (NPs) uniformly dispersed on the polydopamine functionalized MWCNTs (PDA-MWCNTs) has been synthesized. TEM images indicate that MWCNTs are successfully coated by PDA, and the as-prepared PdAu NPs are homogeneously dispersed on the PDA functional MWCNTs with smaller sizes than those on pristine MWCNTs. Electrochemical tests reveal that PDA-MWCNTs is a promising catalyst carrier for direct ethylene glycol fuel cell (DEGFC), and the PdAu(1:1)/PDA-MWCNTs catalyst displays the highest peak current density among all catalysts towards ethylene glycol oxidation reaction (EGOR) in alkaline medium, with mass activity of 1540.3 mA mgPd−1, which is 1.5, 2.6, 9.8, 13.4 and 2.0 times greater than those of PdAu(1:3)/PDA-MWCNTs, PdAu(3:1)/PDA-MWCNTs, Pd/PDA-MWCNTs, Pd/MWCNTs and commercial Pd/C catalysts, respectively. In addition, PdAu(1:1)/PDA-MWCNTs catalyst also exhibits the best stability. These findings are valuable for the development of advanced Pd-based catalysts, which will help promote the industrialization of direct fuel cell.

In this study, Fe/Ni bimetallic nanoparticles were supported on the attapulgite (A-Fe/Ni) to enhance the degradation reactivity of decabrominated diphenyl ether (BDE209) in aqueous solution. The Fe/Ni nanoparticles were well distributed on the attapulgite surface with an average diameter of 20–40 nm. The removal percentage of BDE209 by A-Fe/Ni was 1.59 times higher than Fe/Ni nanoparticles alone because attapulgite could act as supporting material to disperse Fe/Ni nanoparticles and prevent Fe/Ni nanoparticles from aggregation. The degradation kinetics for BDE209 debromination by A-Fe/Ni could be well described by a pseudo-first-order model, and the debromination rate constant of BDE209 increased with increasing the dosage of A-Fe/Ni, water/THF ratio, and decreasing the initial BDE209 concentration and solution pH. The degradation products were identified using a third-order polynomial regression equation between the experimental and reference gas chromatography relative retention times. Stepwise debromination from n-bromo-DE to (n − 1)-bromo-DE was a possible pathway with bromines being substituted sequentially by hydrogen. The preferred elimination of bromines of BDE209 by A-Fe/Ni followed the debromination preference of para-Br > meta-Br > ortho-Br. The results provide evidences for understanding the debromination mechanism of polybrominated diphenyl ether by clay-supported Fe/Ni nanoparticles.

An innovative ex situ soil washing technology was developed in this study to remediate organochlorine pesticides (OCPs) and heavy metals in a mixed contaminated site. Elevated temperature (60 °C) combined with ultrasonication (40 kHz, 20 min) at 50 mL L(-1) maize oil and 45 g L(-1) carboxylmethyl-β-cyclodextrin were effective in extracting pollutants from the soil. After two successive washing cycles, the removal efficiency rates for total OCPs, mirex, endosulfans, chlordanes, Cd, and Pb were approximately 94.7%, 87.2%, 98.5%, 92.3%, 91.6%, and 87.3%, respectively. Cultivation of vetiver grass and addition of nutrients for 3 months further degraded 34.7% of the residual total OCPs and partially restored the microbiological functions of the soil. This result was indicated by the significant increase in the number, biomass C, N, and functioning diversity of soil microorganisms (p

The present study was conducted to investigate the anaerobic biodegradation potential of biostimulation by nitrate (KNO3) and methyl-β-cyclodextrin (MCD) addition on an aged organochlorine pesticide (OCP)-contaminated paddy soil. After 180 days of incubation, total OCP biodegradation was highest in soil receiving the addition of nitrate and MCD simultaneously and then followed by nitrate addition, MCD addition, and control. The highest biodegradation of chlordanes, hexachlorocyclohexanes, endosulfans, and total OCPs was 74.3, 63.5, 51.2, and 65.1%, respectively. Meanwhile, MCD addition significantly increased OCP bioaccessibility (p < 0.05) evaluated by Tenax TA extraction and a three-compartment model method. Moreover, the addition of nitrate and MCD also obtained the highest values of soil microbial activities, including soil microbial biomass carbon and nitrogen, ATP production, denitrifying bacteria count, and nitrate reductase activity. Such similar trend between OCP biodegradation and soil-denitrifying activities suggests a close relationship between OCP biodegradation and N cycling and the indirect/direct involvement of soil microorganisms, especially denitrifying microorganisms in the anaerobic biodegradation of OCPs.

Continuous particle number concentration and chemical composition data were collected over one month during summertime in Beijing to investigate the source apportionment of ambient fine particles. Particle size distributions from 15 nm to 2.5 μm in diameter and composition data, such as organic matter, sulfate, nitrate, ammonium, chlorine, and gaseous pollutants, were analyzed using positive matrix factorisation (PMF) which indentified eight factors: cooking, solid mode exhaust, nucleation mode exhaust, accumulation mode, secondary nitrate, secondary sulfate, coal-fired power plant and road dust. Nearly two-thirds of particle number concentrations were attributed to cooking (22.8%) and motor vehicle (37.5%), whereas road dust, coal-fired power plant and regional sources contributed 69.0% to particle volume concentrations. Local and remote sources were distinguished using size distributions associated with each factor. Local sources were generally characterised by unimodal or bimodal number distributions, consisting mostly of particles less 0.1 μm in diameter, and regional sources were defined by mostly accumulation mode particles. Nearly one third of secondary nitrate and secondary sulfate was transported from the surrounding areas of Beijing during study period. Overall the introduction of combination of particle number concentration and chemical composition in PMF model is successful at separating the components and quantifying relative contributions to the particle number and volume population in a complex urban atmosphere.