Search

Per- and polyfluoroalkyl substances (PFAS) reduction via the hydrated electron yields highly fluorinated (and thus still concerning) transformation products, which can be characterized via nontarget analysis using high-resolution mass spectrometry.

Soot particles emitted from the burning of solid fuel sources in the households carry important environmental and public health implications. In this study, the indoor soot particles released from firewood, cow dung, and bagasse burning at households of selected rural areas of Khyber Pakhtunkhwa province of Pakistan were investigated by characterization analyses to study its morphological and elemental compositions. Results demonstrated diverse compositions of soot particles from each fuel source. The surface areas of soot particles emitted by the firewood, cow dung, and bagasse were about 0.3, 0.4, and 8.64 m2 g-1 , respectively. For the soot particles emitted by the firewood burning, the major functional groups for aromatic compounds were C═C at the 1,431-1,599 at 1,000-2,000 cm-1 . The absorbance rate of alkanes was about 1,599-1,431 at 1,000-2,000 cm-1 . However, silicon band vibration was more prominent in bagasse soot particles as compared to other samples. The emission of soot particles with high surface area in the atmosphere could provide an elevated adsorption sites for atmospheric pollution and trap more energy resulting in increased atmospheric temperature. Findings from the present study suggest that current households' fuel combustion practices significantly contribute to increase the particulate matter in the atmosphere and possible enhance climate change phenomenon and related disasters in northern Pakistan.

Groundwater contamination by halogenated organic compounds, especially fluorinated ones, threatens freshwater sources globally. Sulfidized nanoscale zero-valent iron (SNZVI), which is demonstrably effective for dechlorination of groundwater contaminants, has not been well explored for defluorination. Here, we show that SNZVI nanoparticles synthesized via a modified post-sulfidation method provide rapid dechlorination (∼1100 μmol m-2 day-1) and relatively fast defluorination (∼6 μmol m-2 day-1) of a halogenated emerging contaminant (florfenicol) under ambient conditions, the fastest rates that have ever been reported for Fe0-based technologies. Batch reactivity experiments, material characterizations, and theoretical calculations indicate that coating S onto the metallic Fe surface provides a highly chemically reactive surface and changes the primary dechlorination pathway from atomic H for nanoscale zero-valent iron (NZVI) to electron transfer for SNZVI. S and Fe sites are responsible for the direct electron transfer and atomic H-mediated reaction, respectively, and β-elimination is the primary defluorination pathway. Notably, the Cl atoms in florfenicol make the surface more chemically reactive for defluorination, either by increasing florfenicol adsorption or by electronic effects. The defluorination rate by SNZVI is ∼132-222 times higher with chlorine attached compared to the absence of chlorine in the molecule. These mechanistic insights could lead to new SNZVI materials for in situ groundwater remediation of fluorinated contaminants.

Atomic H* has been regarded as the key active species for the electrocatalytic hydrodechlorination (ECH), and the electrode design and operation conditions are related to the atomic H* generation. However, there is limited understanding of how the operation parameters affect the atomic H* generation and utilization. Due to the fact that Pd was inefficient in water dissociation step, MnO2 was combined with Pd to construct a novel Pd/MnO2/Ni foam cathode. Cyclic voltammetry confirmed that Pd/MnO2/Ni foam cathode with MnO2 load of 0.51 mg cm−2 possessed the highest atomic H* generation and ECH activity. Excessive Pd load (>0.44 mg cm−2) was detrimental to ECH because of the side hydrogen evolution reaction (HER). Operation conditions (e.g. applied current and electrolyte concentration) would directly affect the cathode potential, which was an important indicator of the atomic H* generation. The optimal cathode potential was determined to be −0.85 V when the applied current was 10 mA in this study. The electrolyte concentration of 10–15 mM was able to provide sufficient atomic H* for ECH, while excessive input of electrolyte would favor HER but inhibit ECH. ECH at acidic and neutral/alkaline solution underwent different pathways for atomic H* generation and further affect the utilization of atomic H*. After 120 min reaction, >70% of atomic H* could be selectively used for ECH at initial pH of 4.0 and 5.0, while only ∼37% was used for ECH at initial pH of 7.0. This work correlated the reactivity of electrode with the atomic H* and cathode potential, which would provide strategies for ECH catalyst design and operation optimization.

In this study, a novel approach was developed for the dechlorination of 2,4-dichlorobenzoic acid (2,4-DCBA) via the combination of the moveable activated carbon (AC) supported palladium (Pd) nanoparticles and nickel (Ni) foam electrode. The morphology and chemical structure of Pd/AC catalyst was investigated by various characterization techniques, including SEM, TEM, EXS-mapping, XRD, and XPS. Pd nanoparticles was successfully loaded and dispersed on the AC, accompanied with the significantly enhanced reactivity. The removal rate of 2,4-DCBA by Ni electrode with moveable Pd/AC catalyst was 222, 25, and 5 folds higher than dispersed AC and Ni electrode system, chemical deposited Pd/Ni electrode, and electrodeposited Pd/Ni electrode, respectively. Compared with the conventional electrocatalytic reductive approach which deposited Pd on the Ni foam electrode, moveable Pd/AC catalyst possesses higher surface area, more atomic H∗ production and more active sites, favored mass transfer, and enhanced reactivity, without the consideration of catalyst loss and deactivation. The effects of Pd:AC mass ratio, constant current, initial solution pH, and electrolyte concentration on the dechlorination of 2,4-DCBA were studied. Generally, high Pd loading, constant current, and acidity favored the dechlorination of 2,4-DCBA, while excessive electrolyte would inhibit the dechlorination of 2,4-DCBA. Good longevity and recyclability of moveable Pd/AC catalyst was confirmed via consecutive experiments. The findings of the present study show that making the catalyst moveable is a promising strategy for electrocatalytic remediation technology.

Coastal wetlands are widely recognized as atmospheric methane sources. However, recent field studies suggest that some coastal wetlands could also act as methane sinks, but the mechanism is not yet clear. Here, we investigated methane oxidation with different electron acceptors (i.e., oxygen, nitrate/nitrite, sulfate, Fe(III) and Mn(IV)) in four coastal wetlands in China using a combination of molecular biology methods and isotopic tracing technologies. The geochemical profiles and in situ Gibbs free energies suggest that there was significant nitrite-dependent anaerobic oxidation of methane (nitrite-AOM) in the sub-surface sediments; this was subsequently experimentally verified by both the microbial abundance and activity. Remarkably, the methanotrophic communities seemed to exist in the sediments as layered structures, and the surface aerobic methane-oxidizing bacteria were able to take up atmospheric methane at a rate of 0.10–0.18 nmol CH4 day−1 cm−2, while most, if not all, sedimentary methane was being completely consumed by anaerobic methanotrophs (23–58% by methane oxidizers in phylum NC10). These results suggest that coastal methane sinks might be governed by diverse microbial communities where NC10 methane oxidizers contributed significantly. This finding helps to better understand and predict the coastal methane cycle and reduce uncertainties in the estimations of the global methane flux.

Fe-Mn binary oxides (FMBO) with different Fe/Mn molar ratios were synthesized to investigate the influence of the changed iron oxides forms and the manganese oxide on the removal efficacy of Sb(V) from water under neutral pH. The characterization tests by electron microscopy and X-ray diffraction spectroscopy showed that FMBO gradually changed from granular to aciculiform or fibrous structure and their crystalline degree increased with the decreasing Mn content. The ferric oxides in FMBO transformed from 2-L ferrihydrite-like substance with amorphous state to goethite or lepidocrocite with high crystalline as the amount of added Mn reduced during the preparation. The Sb(V) adsorption rates and capacities of FMBO both decreased and the influence of pH on the Sb(V) removal became greater with the decreasing Mn oxide content. All the results indicated that the addition of Mn could greatly improve the Sb(V) removal performance of FMBO through promoting the formation and preventing the transformation of amorphous ferric oxide in FMBO during the preparation, whose Sb(V) adsorption ability was confirmed to be stronger than that of goethite or lepidocrocite. Further exploration indicated the complexation reaction between Sb(V) and amorphous ferric oxide played a key role in Sb(V) adsorption by FMBO. Meanwhile, FMBO with a Fe/Mn molar ratio of 3:1 (FMBO3) exhibited excellent regeneration performance and the amorphous iron oxide in FMBO3 gradually transformed into crystalline iron oxide during the consecutive recycling.

A Pd/MnO2/Ni foam electrode with hierarchical structure was synthesized via electrodeposition for efficient electrocatalytic hydrodechlorination. Compared with the ordinary Pd/Ni foam electrode, the introduction of MnO2 greatly enhanced the catalytic reactivity and reduced the dose of precious metal Pd. Only a quarter of Pd was required for the Pd/MnO2/Ni foam compared to the Pd/Ni electrode to achieve complete dechlorination of 2,4-dichlorobenzoic acid (2,4-DCBA) within 120 min. Various characterizations suggested that MnO2 covered the surface of the Ni foam and increased the specific surface area of the electrode, while Pd nanoparticles were subsequently deposited on MnO2. The atomic H∗-based indirect dechlorination was the dominant pathway while only approximately 13% of 2,4-DCBA was removed by direct electron transfer. Atomic H∗ adsorbed on Pd acted as the key active species for the dechlorination of 2,4-DCBA by the Pd/MnO2/Ni foam electrode in this study. The introduction of MnO2 would promote the water dissociation and the hydrogen evolution reaction, and provide Pd with more atomic H∗. Pd/MnO2/Ni foam exhibited good stability and reusability according to the XPS spectra and consecutive electrocatalytic experiments, which suggested its long-term potential for efficient removal of chlorinated contaminants. This work demonstrated a new strategy to design efficient electrocatalysts with less precious metal.

Black carbon (BC) plays a crucial role in the migration, transformation, and remediation of hydrophobic organics (HOCs) in soil/sediment. Previous studies mainly focus on the sorption characteristic of BC, while the chemical degradability of HOCs, which is affected by sequestration and catalytic effects of BC, has not yet been systematically studied. In this study, the dechlorination process of 2-chlorobiphenyl (PCB1), adsorbed on BC prepared at different pyrolysis temperatures, by bimetal modified nano zero-valent iron (nZVI/Pd) was investigated. The results showed that, on the one hand, adsorption limited the dechlorination process. PCB1 in the resistant desorption state exhibited lower degradation efficiency than that in other adsorption state. On the other hand, the catalysis of high-temperature BC reduced the inhibition of adsorption on dechlorination to some extent. As the pyrolysis temperature rose from 400 °C to 900 °C, the degradation efficiency of adsorbed PCB1 within 48 h improved from 53.5% to 95.3%, and the rate constant (kobs) increased from 0.104 h−1 to 0.197 h−1. High-temperature BC promoted the electrons release of Fe0 and the generation of [H], and its conductivity improved the electron utilization efficiency so that the dechlorination reaction could proceed both on the surface of nZVI/Pd particles and BC, thereby promoting the dechlorination of PCB1. Therefore, adsorption effect dominated degradability of PCB1 sequestrated by low-temperature BC, while for high-temperature BC, synergistic catalytic effect played a dominant role. These findings indicate that reductive efficiency of nZVI should be systematically evaluated according to different types of BC in soil/sediment.

An ecofriendly and practical method for the efficient synthesis of various sulfonylated N-heteroaromatics in water under metal-free, organic-solvent-free, neutral, and mild reaction conditions was developed. The employment of readily available reagents, wide substrate scope, high chemoselectivity, and regioselectivity make this protocol very practical. Importantly, the pure products can be easily obtained via filtration and washing by alcohol without extraction and recrystallization.

Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) are ubiquitous and highly toxic emerging endocrine disruptors found in surface and subsurface soils and clay deposits. Seriously, they could be easily transformed to the more toxic dioxins (PBDD/Fs) in photochemical processes and incineration, but the spontaneous formation of PBDD/Fs has rarely been reported. This study focused on the formation of 1,3,8-tribromodibenzo-p-dioxin (1,3,8-TrBDD) and 2,4,6,8-tetrabromodibenzofuran (2,4,6,8-TeBDF) from 2′-OH-BDE-68 and 2,2′-diOH-BB-80 under the oxidization of iron and manganese oxides (goethite and MnOx). Approximately 0.09 μmol/kg (2.33%) and 0.17 μmol/kg (4.15%) were transformed to 1,3,8-TrBDD and 2,4,6,8-TeBDF by goethite in 8 days and a higher conversion 0.15 μmol/kg (3.77%) and 0.23 μmol/kg (5.74%) were observed for MnOx in 4 days. However, the formation of PBDD/Fs, probably proceeding via Smiles rearrangements and bromine elimination processes, was greatly inhibited by the presence of water. Transformation of OH-PBDEs by goethite and MnOx was accompanied by release of Fe and Mn ions and the possible pathways for the formation of reaction products were proposed. In view of the ubiquity of OH-PBDEs and metal oxides in the environment, oxidation of OH-PBDEs mediated by goethite and MnOx is likely an abiotic route for the formation of PBDD/Fs.

Polychlorinated dibenzo-p-dioxins (PCDDs), as a group of notorious anthropogenic environmental toxicants, are arguably ubiquitous in nature. In this study, we investigated the photocatalytic reductive dechlorination of 2-chlorodibenzo-p-dioxin (2-CDD) over Pd/g-C3N4 catalysts under UV–vis irradiation. The g-C3N4 and a series of Pd/g-C3N4 catalysts were prepared by thermal polymerization and mechanical mixing-illumination method and characterized by XRD, TEM, BET, SEM and UV–vis DRS analyses. Among all the samples, the Pd/g-C3N4 (5 wt%) yielded the optimal dechlorination activity with a total 2-CDD conversion of 54% within 4 h, and 76% of those converted 2-CDD were evolved to dibenzo-p-dioxin (DD). The kinetics of dechlorination could be described as pseudo-first-order decay model (R2 > 0.84). Corresponding rate constants (k) increased from 0.052 to 0.17 h−1 with Pd contents up to 5 wt% and decreased to 0.13 h−1 with a 10 wt% of Pd. The enhanced activities originated from the surface plasmonic resonance (SPR) effect of Pd nanoparticles and the formation of Schottky barrier between Pd and g-C3N4, which extend the spectrum responsive range and suppress the charge recombination of g-C3N4. This is the first report on the photocatalytic reductive removal of PCDDs and may provide a new approach for PCDDs pollution control.

Iron sulfide (FeS) nanoparticles with large specific surface area and abundant pore structure have been recognized as effective Hg(II) adsorbents. However, bare FeS nanoparticles can aggregate easily, which greatly limited their engineering applications. In this study, FeS nanoparticles were stabilized by biomaterials, including sodium carboxymethyl cellulose (CMC), gelatin and starch, and thoroughly investigated for the stabilization effects. Results demonstrated that the three biomaterial stabilized FeS nanoparticles namely CMC-FeS, gelatin-FeS and starch-FeS enhanced the adsorption efficiency significantly. The maximum adsorption capacities of CMC-FeS, gelatin-FeS and starch-FeS (mass ratio of stabilizer to FeS was 1:6) achieved ∼1726 mg/g, ∼1939 mg/g and ∼1989 mg/g respectively, which were over twice of the bare FeS. TEM images suggested that biomaterial-FeS nanoparticles were dispersed more uniformly than bare FeS. The removal processes of the three materials obeyed pseudo-second-order kinetic model (R2 ≥ 0.9986), implying that the rate-limiting step was the chemical sorption process. High removal efficiency of biomaterial-FeS nanoparticles was observed in the initial pH range of 6–11. The presence of Cl− could accelerate the reaction process, whereas the presence of humic acid (HA) could inhibit Hg(II) uptake. In addition, high concentration of coexisting cations (30 mM as Cd2+, Pb2+, Cu2+, and Ca2+) had no significant effect on Hg(II) removal.

An economic and eco-friendly straightforward synthesis of highly diversified N-acylated 2-aminoquinolines is successfully achieved via Bronsted acidic ionic liquid-promoted amidation of quinoline N-oxides with nitriles. The advantage of this present process is highlighted by its easily accessible starting materials, excellent functional group tolerance, 100% atom economy, operational simplicity, and clean reaction profile.

An economic, safe, practical, and environmentally benign protocol for the oxidation of aldehydes to carboxylic acids and acid anhydrides with ambient air as the sole oxidant was developed. This oxidation is operationally simple and external catalyst-, initiator-, and base-free, with outstanding functional group tolerance (moisture-, acid-, base-, and oxidant-sensitive groups). It also provides a practical protocol for large scale synthesis (>100 g), late-stage modification of polyfunctional compounds, and one-pot sequential transformation starting from aldehydes.

We describe an eco-friendly, practical and operationally simple procedure for the bis(methoxypropyl) ether-promoted oxidation of aromatic alcohols into aromatic carboxylic acids and aromatic ketones with atmospheric dioxygen as the sole oxidant. This chemical process is clean with high conversion and good selectivity, and an external initiator, catalyst, additive and base are not required. The virtue of this reaction is highlighted by its easily available and economical raw materials and excellent functional group tolerance (acid-, base- and oxidant-labile groups).

By using water as the hydrogen source, an eco-friendly and practical protocol for the synthesis of Z-vinyl thiocyanates through ultrasound-promoted Bronsted acid ionic liquid-catalyzed hydrothiocyanation of activated alkynes under minimal solvent conditions has been developed. This process effectively avoids the use of organic solvents, metal catalysts and harsh reaction conditions. This reaction shows attractive characteristics such as operational simplicity, broad substrate scope with good to excellent yields, ease of scale-up and high energy efficiency and recyclable and reusable catalysts.

The present study aimed to investigate biodegradation mechanisms of black carbon (BC)-bound contaminants in BC-amended sediment when BC was applied to control organic pollution. The single-point Tenax desorption technique was applied to track the species changes of nonylphenol (NP) during biodegradation process in the rice straw carbon (RC)-amended sediment. And the correlation between the biodegradation and desorption of NP was analyzed. Results showed that microorganisms firstly degraded the rapid-desorbing NP (6 h Tenax desorption) in RC-amended sediment. The biodegradation facilitated the desorption of slow-desorbing NP, which was subsequently degraded as well (192 h Tenax desorption). Notably, the final amount of NP degradation was greater than that of NP desorption, indicating that absorbed NP by RC amendment can be degraded by microorganisms. Finally, the residual NP amount in RC-amended sediment was decided by RC content and its physicochemical property. Moreover, the presence of the biofilm was observed by the confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM) so that microorganisms were able to overcome the mass transfer resistance and directly utilized the absorbed NP. Therefore, single-point Tenax desorption alone may not be an adequate basis for the prediction of the bioaccessibility of contaminants to microorganisms or bioremediation potential in BC-amended sediment.

The CTAB-Pd/GAC catalyst was obtained by functionalizing palladium/granular activated carbon (Pd/GAC) with cetyltrimethylammonium bromide (CTAB), which was used for the electrocatalytic reductive dechlorination of 2,4-dichlorobenzoic acid (2,4-DCBA). The degradation rate of 2,4-DCBA by 40 mg g−1 CTAB-Pd/GAC was 9.8 × 10−3 (min−1 g−1 Pd), which was 11 folds than that by Pd/GAC (0.9 × 10−3 min−1 g−1 Pd), and the value of qe, 2,4-DCBA/qe, BA was 2.33 as compared to 0.67 for Pd/GAC. The combined result of dechlorination and adsorption experiments suggested that the functionalization by CTAB would enhance the 2,4-DCBA concentration on the surface of CTAB-Pd/GAC, and accelerate the degradation rate. However, the removal efficiency of 2,4-DCBA would decrease when the CTAB load reached 80 mg g−1, due to the excessive adsorption capacity for dechlorinated product. Density functional theory (DFT) calculations also proved that CTAB would increase adsorption capacity of catalyst and selective adsorption behavior of 2,4-DCBA, which accelerated the degradation rate of 2,4-DCBA.

Iron sulfide (FeS) nanoparticles were known for their excellent ability to scavenge aqueous Hg(II). However, the aggregation and oxidizability of FeS nanoparticles greatly restricted their practical application. This study developed an Al 2 O 3 -supported nanoscale FeS (FeS/Al 2 O 3 ) which effectively optimized the material performance. Characteristic data suggested that FeS/Al 2 O 3 (mass ratio of FeS to FeS/Al 2 O 3 is 30%) with a large specific surface area (142.7 m 2 g −1 ) could evenly distribute FeS, suppressing the aggregation of FeS successfully. The maximum enrichment capacity of Hg(II) on FeS/Al 2 O 3 achieved ∼313 mg/g at pH 6 and 30 °C. The pH studies indicated that alkaline environment strongly inhibited mercury uptake, while removal rate of 1 mg/L Hg(II) maintained a high level (>97.5%) over the pH range of 3–9. However, FeS/Al 2 O 3 loss was observed at low pH due to the acid corrosion. Additionally, the rates of Hg(II) reduction were almost unaffected over the range of 0.1–100 mM NaCl, but greatly inhibited by the presence of humid acid (HA). The synthetic FeS/Al 2 O 3 remained high mercury removal efficiency (over 95% in 1 mg/L Hg(II)) and low iron dissolution rate when preserved for 30 days, showing good long-term stability and remarkable application potential.

In this study, reduced graphene oxide (RGO) and different stabilizers (hexadecyltrimethylammonium bromide, starch, and carboxymethyl cellulose) were applied to simultaneously support and stabilize Fe-Mn binary oxide (FeMnOx) nanohybrids, and enhanced removal of As(III)/(V) from water was achieved. TEM images shows that the aggregation of FeMnOx on RGO was effectively inhibited after the starch stabilization, meanwhile, the loading of FeMnOx on RGO was also increased. The adsorption capacity of As(III) and As(V) on starch-FeMnOx/RGO via Langmuir isotherm model was 78.74 mg g−1 and 55.56 mg g−1, respectively, which was 1.99 and 2.39 times higher than bare FeMnOx. The adsorption kinetics was well fitted by the pseudo-second-order model. The effects of initial pH and coexisted anions were investigated. Over 90% of As(III) and As(V) could be removed by starch-FeMnOx/RGO during the five consecutive adsorption-desorption cycles. The results revealed the potential of the RGO supported and starch stabilized FeMnOx as an efficient adsorbent for arsenic removal from water.

Multilayer Zn-doped SnO 2 nanospheres are successfully synthesized by using Sn/Zn bimetal-organic nanoparticles as precursor. These multilayer spheres are found to be very suitable for solving the critical volume expansion problem and mass transfer property due to its high surface area, small crystal size and hollow structure, which is critical for high capacity metal oxide electrodes for lithium-ion batteries. Moreover, the covalently interconnected three-dimensional graphene foams encapsulated these multilayer spheres are successfully obtained through self-assembly effect and chemical cross-linking of graphene oxide nanosheets. The graphene network could further greatly improve the cycling stability and rate capability of the Zn-doped SnO 2 spheres electrode due to its flexible buffering matrix and high electric conduction. As a result, the graphene encapsulating multilayer Zn-doped SnO 2 spheres anodes exhibit excellent rate capacity and a high reversible capacity of 446 mA h g −1 even after 1000 cycles at the current density of 1 A g −1 . These excellent electrochemical performances are ascribed to its large specific surface area, fast electron/ion transfer, and stable electrode structure. Furthermore, this strategy using covalently interconnected 3D graphene foams encapsulate the Zn-doped SnO 2 spheres not only develops a high performance anode material with long cycle life but also holds great promise for binder-free lithium ion batteries.

The observed strong sorption of hydrophobic organic contaminants (HOCs) to biochar presents potential implications for HOCs bioavailability and bioaccessibility in sediments, while biochar could impact sediment microbial ecology. However, the comprehensive study on the effects of biochar on HOC biodegradation coupled with bioavailability and microbial ecology are rarely documented. In this paper, the effects of biochar on the biodegradation of nonylphenol (NP) were investigated using 3 different NP concentrations (20, 50 and 500 mg/Kg) in sediments amended with different percentage of rice straw biochar (RC). Results showed that the influence of RC on NP biodegradation varied with different NP concentrations. At low NP concentrations, RC suppressed NP biodegradation by reducing NP bioavailability, while at high NP concentrations, moderate RC addition promoted biodegradation by reducing toxicity of NP to microbes. The effects of NP on microbial community structures were significant (P P > 0.05). The RC affected microorganisms through altering NP toxicity, microbial quantity and activity, but not microbial community structures. This study indicated that there could be an optimal biochar percentage in biochar-sediment systems at different HOC concentrations, which strengthened HOC biodegradation process and accelerated biodegradation rate, forming adsorption-biodegradation coupled bioremediation.

To effectively remove N and P from eutrophic water, the Phragmites australis after phytoremediation was harvested for preparation of modified biochar. The MgCl2-modified biochar (MPB) was successfully synthesized at 600 °C under N2 circumstance. The physiochemical characteristics, the adsorption capacity for N and P in the simulated solution, and their adsorption mechanism of MPB were then determined, followed by the treatment of eutrophic water of Tai lake and its inflow river from agricultural source. The results demonstrated that the MPB presented high adsorption capacity to both simulated NH4-N and PO4-P with the maximum adsorption capacity exceeding 30 and 100 mg g−1, respectively. The entire ammonium adsorption process could be described by a pseudo-second-order kinetic model whereas the phosphate adsorption process could be divided into three phases, as described by both intra-particle diffusion model and the pseudo-first-order kinetic. It was further found that the dominant mechanism for ammonium adsorption was Mg2+ exchange instead of functional groups and surface areas and the Mg-P precipitation was the main mechanism for phosphate adsorption. The MPB also showed high removal ratio of practical TP which reached nearly 90% for both the water in Tai lake and its agricultural source. It suggested that MPB based on harvested P. australis was a promising composite for eutrophic water treatment and it could deliver multiple benefits.

A highly efficient way for the direct (trans)esterification of acyl acids (esters) and alcohols in a strict 1 : 1 ratio using a zirconocene complex (1, 1 mol%), a strong Lewis acid of good water tolerance, as a catalyst under solvent-free conditions has been developed. A wide range of acid and alcohol (esters) substrates undergo (trans)esterification to produce carboxylic ester motifs in moderate to good or excellent yields with good functional tolerance, such as that towards C–Br as well as CC and CC bonds. And complex 1 can be recycled six times without showing a significant decline in catalytic efficiency. It was demonstrated that cyclandelate, which is used to treat high blood pressure as well as heart and blood-vessel diseases, can be directly synthesized on a gram scale with 81% yield (6.70 g) using complex 1.

Exposing nanoscale zerovalent iron (NZVI) to dissolved sulfide species improves its performance as a remediation agent. However, the impacts of sulfur dose and sulfidation time on morphology, sulfur content, reactivity, and selectivity of the resulting sulfidized NZVI (SNZVI) have not been systematically evaluated. We synthesized SNZVI using different sulfur doses and sulfidation times and measured their properties. The measured S/Fe molar ratio in the particles ([S/Fe]

Modified nanoscale zero-valent iron (nZVI) is a promising functional material for the remediation of combined pollutants involving polychlorinated biphenyls (PCBs) and heavy metals. However, the interaction between the two types of pollutants has not been systematically studied for this method of treatment. In this study, 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB153), Cu2+, and Ni2+ were selected as the target pollutants. To understand the interaction between pollutants, the efficiencies of nZVI, sulfidated nZVI (S-nZVI), and carboxymethylcellulose stabilized nZVI (CMC-nZVI) were investigated for removal of PCB153, Cu2+/Ni2+, and combined pollution system (PCBs-Cu2+/Ni2+). Results showed that the removal kinetics of the two types of pollutants by the three materials fitted a pseudo-first-order model well and that the reaction mechanisms were similar. Among the three materials, CMC-nZVI showed the highest reactivity to degrade PCB153 (pseudo-first-order kinetic constants (kobs) = 2.7 × 10−4 min−1) and remove Cu2+ (kobs = 2.890 min−1), while S-nZVI showed higher affinity for the removal of Ni2+ (kobs = 0.931 min−1). For the combined pollution system, PCB153 had little effect on the removal of heavy metals by the three materials, while the effect of heavy metals on PCB153 degradation was related to the types of heavy metals and the materials. Cu2+ had no significant effect on PCB153 degradation by the three materials, while the coexistence of Ni2+ promoted PCB153 degradation by nZVI and CMC-nZVI. XPS and electrochemical analysis showed that Cu0 and Ni0 were produced on the surface of the three materials. Ni is a more effective catalyst and promoted the electron transfer efficiency of the materials and had a positive impact on the dechlorination reaction.

Sulfidation of nanoscale zerovalent iron (nZVI) has attracted increasing interest for improving the reactivity and selectivity of nZVI towards various contaminants, such as aqueous Cr(VI) removal. However, the benefits derived from sulfide modification that govern the removal of Cr(VI) remains unclear, which was studied in this work. S-nZVI with higher S/Fe molar ratio showed higher surface area, the discrepancy between the surface-area-normalized removal capacity of Cr(VI) by S-nZVI with different S/Fe indicated that the removal of Cr(VI) was also affected by other factors, such as electron transfer ability, surface-bounded Fe(II) species, and surface charges. High specific surface area would provide more active site for Cr(VI) removal, and as an efficient electron conductor, acicular-like FeSx phase would also favor electron transfer from Fe0 core to Cr(VI). Low initial pH also enhanced the Cr(VI) removal, and the Cr(VI) removal capacity by S-nZVI and nZVI was not affected by aging process, these results confirmed that the Fe(II) species also played an important role in the Cr(VI) removal. Other influence factors were also investigated for potential application, including temperature, initial Cr(VI) concentration, ionic strength, and co-existed ions. The removal mechanism of Cr(VI) by S-nZVI involved the sulfide modification to increase the specific surface area and provide more active sites, the corrosion of Fe0 to produce surface-bounded Fe(II) species to adsorb Cr(VI) species, followed by the favored reduction of Cr(VI) to Cr(III) due to the electron transfer ability of FeSx, then the formation of Cr(III)/Fe(III) hydroxides precipitates.

In this study, the selective adsorption performance of different Fe-Mn binary oxides (FMBOs) towards Sb(V) in the textile wastewater under different concentrations of coexisting anions, surfactants and dyes were investigated. Results showed that the influences of different anions on the Sb(V) removal followed an order of phosphate > carbonate > sulfate > nitrate > chloride. The frequently-used organic acid of acetate was found to have insignificant effect. The coexisting surfactant with sulfonic groups could have adverse effect on the removal due to sulfonic groups could compete the adsorptive sites on Fe oxides with Sb(V). While the quaternary ammonium surfactant might have minor effect. The influences of the three widely used dyes on the Sb(V) adsorption decreased in the following order: reactive black-5 >acid orange-7> disperse blue-60, which confirmed that the dyes with sulfonic groups would have relatively higher effect. The selective adsorption capacities of Sb(V) by FMBOs followed an order of FMBO3> FMBO5 >FMBO10> FMBO20>PFO. Fixed-bed column adsorption supplied useful parameters and evidently indicated that the cyclic utilization of FMBO3 was cost-efficient for practical dynamic Sb(V) removal. The Sb(V) removal by FMBO3 from real textile wastewater can simultaneously improve the removal efficiency, stabilize pH and prevent the increase of iron concentration as compared to the traditional coagulation, further demonstrating the high practical applicability of FMBO3.

The development of amorphous iron oxide-based composites for the Sb(V) removal is limited by their easy phase transformation, aggregation, and unstable nature. Herein, novel modified Si-doped Fe oxide composites (SFOC) were prepared to break through the current obstacle. Characterization results of SFOC with a suitable amount of doped Si indicated that the coordination interaction between Si-OH and Fe-OH blocked the crystal growth sites in both Si and Fe oxide, and the crystal unit cells of same element were difficult to contact with each other. Hence, the crystal growth of Si and Fe oxide was retarded and their unit particle size became smaller. Meanwhile, the crystal phase transformation of amorphous ferrihydrite was prevented and the aggregation extent of Fe oxide was greatly decreased after Si doping. These changes caused that more Fe vacancies were generated on the surface of amorphous Fe oxide unit and the surface area of SFOCs also increased, resulting in the great increasement of exposed Fe hydroxyl groups in SFOC. As compared to pristine Fe oxide, the optimal SFOC10 with Fe/Si molar ratio of 10:1 exhibited the highest surface area of 363.9 m2/g, the maximum Sb(V) removal capacity of 176.1 mg/g, and higher selective Sb(V) adsorption performance. The introduction of Si oxide also endowed SFOC10 with much better phase stability and Sb(V) removal capacity during the long cyclic adsorption-desorption process. Moreover, the inner-sphere complexation of Fe-OH and Sb(OH)6− played a key role in adsorption. Furthermore, optimal SFOC10 was sufficient for the Sb(V) removal from real textile wastewater in both the batch and dynamic column adsorption processes.

Recently, sulfidation of nanoscale zerovalent iron (S-nZVI) has become a potential remediation technology. However, the impact of sulfidation methods and actual sulfur content ([S/Fe]particle) on the physicochemical properties and the reactivity of S-nZVI remains unknown. Here, we synthesized S-nZVI via one co-sulfidation and three post-sulfidation methods to determine how different sulfur reagents and addition procedures affect the reactivity of S-nZVI for defluorination. The measured S amounts of co-sulfidized S-nZVI and post-sulfidized S-nZVI was much lower than their dose. Different sulfur reagents and sulfidation approach would affect the amount and speciation of sulfur in the particles. Sulfidation of nZVI improved the reactivity for dechlorination (up to 12-fold) and defluorination (up to 3-fold) of florfenicol (FF), but inhibited the reactivity with water (up to 31-fold). Density functional theory calculations showed that sulfidation increases the hydrophobicity of materials, and the amount and nature of sulfur affect the hydrophobicity and the number of blocked H sites. S-nZVI particles with more S2− and S22− species showed faster dechlorination and defluorination of FF. Up to ~ 45% of FF was defluorinated by S-nZVI after 15 days reaction at room temperature and pressure. The [S/Fe]particle and Fe0 content was responsible for the initial and long-term defluorination, respectively. These results suggest that S-nZVI could be a promising agent for defluorination, and the sulfur reagents and sulfidation approach would affect its properties and reactivity.

A novel biological nitrogen removal process can be developed based on the newly discovered nitrite-dependent anaerobic methane oxidation (n-damo) process. In this work, the short- and long-term effects of mineral nutrients on the n-damo process were investigated by single-factor and orthogonal experiments, respectively. The pH buffering capacities of different media were determined by acid–base titration. KHCO3 and KH2PO4 greatly influenced the activity of n-damo bacteria and the pH changes of the media. An improved n-damo medium was proposed, containing 0.3 g L−1 CaCl2, 0.2 g L−1 MgSO4, 0.3 g L−1 KH2PO4 and 0.2 g L−1 KHCO3. Moreover, the presence of 1% of CO2 in gas could maintain the pH near neutral in the improved medium, which was first estimated in theory and then verified in practice. Finally, these results were applied in an n-damo reactor. The nitrogen removal rate was slightly increased (from 10.0 ± 1.2 to 10.8 ± 1.4 mg N L−1 d−1), and the pH was quite stable after the improvement (daily changes from 0.58 ± 0.05 to 0.11 ± 0.02).

In this study, nanosized titanium nitride (nTiN) doped palladium/nickel (Pd/Ni) foam electrodes were prepared via electroless deposition method for the dechlorination of 2,4-dichlorophenoxyacetic acid (2,4-D). Characterization analyses including field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM) revealed that nTiN was successfully doped onto the electrode surface. 2,4-D was first dechlorinated to intermediate products p -chlorophenoxyacetic acid ( p -CPA) or o -chlorophenoxyacetic acid ( o -CPA) and then to the final product, phenoxyacetic acid (PA). The effects of environmental factors including initial 2,4-D concentration, current density, reaction temperature and dissolved anions were also studied. High initial 2,4-D concentration increased the efficient utilization of active hydrogen atom [H] by nTiN doped Pd/Ni foam electrodes. Increases in current density promoted better dechlorination efficiency while the hydrogen evolution side reaction was undesirably increased, leading to a lower average current efficiency. Higher reaction temperature was proved to be favorable for the enhancement of dechlorination efficiency. NO 3 − and reduced sulfur compounds including S 2− and SO 3 2− showed negative impacts on Pd catalytic capability, whereas CO 3 2− and Cl − exhibited less adverse effects on dechlorination efficiency. The activation energy ( E a) value of 2,4-D dechlorination by nTiN doped Pd/Ni foam electrode was calculated to be 32.06 kJ mol −1 . Two typical stages namely electrode activation and efficient dechlorination procedures occurred in 2,4-D dechlorination by nTiN doped Pd/Ni foam electrodes. The reaction paths of [H] on the electrode were also summarized. The removal efficiency of 2,4-D dechlorination on nTiN doped Pd/Ni foam electrodes was observed to slightly decrease from 100% to 89.95% after 5 consecutive experiments.

The binding order of sorbent, sediment and organic compounds, as well as binding time is important factors determining the potential success of sorbent amendment, which should be considered when the practicability of sorbents was assessed. But until now, relevant research was rare. In this study, desorption in three practical conditions were simulated, by three mixing spiking orders among nonylphenol (NP), rice straw black carbon (RC) and sediment (the order of mixing spiking is (RC+Sediment)+NP, (Sediment+NP)+RC and (RC+NP)+Sediment, for situation I, II and III, respectively), to discuss the feasibility of using RC to remedy NP pollution. Results demonstrated that amendment of RC into sediment decreased desorption fractions of NP, and increased the resistant desorption fraction (Fr), implying strong affinity of NP to RC and efficient sequestration by RC. No significant differences were observed for desorption among the three fresh situations, meaning NP may be adsorbed on RC exterior surface sites and inter-phase diffusion is faster than desorption. However, Fr for three aged situations was in the order: situation IIIIII, due to NP diffusion into the inter-pores or irreversible sorption sites of RC, reducing the releasing risk of NP. Regardless of time, Fr of three situations were all0.5, suggesting RC is an effective sorbent for remedying NP pollution in the aquatic environment. Overall, we proposed a practical and analytical method for properly assessing the validity of a sorbent.

Sulfidized nanoscale zerovalent iron (S-nZVI) has been reported to be highly reactive towards lots of contaminants. However, the effects of surface chemistry evolution (e.g. surface S/Fe) and hydrophobicity on its reactivity and selectivity towards the reduction of different functional groups on contaminants are unclear. Here, the reactivity and electron selectivity of aged nZVI and S-nZVI in water for the denitration of chloramphenicol (CAP) and dechlorination of florfenicol (FF) were investigated. The reactivity of nZVI for the denitration of CAP was greatly inhibited after sulfidation, and the kobs, CAP by nZVI decreased along with the aging time. However, the reactivity of nZVI for the dechlorination of FF was significantly improved after sulfidation, and the kobs, FF by S-nZVI firstly increased then decreased with the aging time, which was correlated well with the evolution of S/Fe molar ratio on the surface. S-nZVI with higher hydrophobicity was proved to be more reactive for the dechlorination of FF but less reactive for the denitration of CAP. Interestingly, the electron efficiencies of CAP denitration by nZVI and FF dechlorination by S-nZVI were both maintained >99% no matter the materials were fresh or aged. These results revealed that the sulfidation would change the physicochemical properties and reactivity of nZVI, and it is of great importance to measure the surface chemical composition and hydrophobicity of S-nZVI and apply the materials with appropriate target contaminants to maximum the electron utilization.

Self-healable and stretchable electrolytes are extremely desirable for next-generation flexible energy storage devices. Nevertheless, most of previously reported autonomous self-healing electrolytes possess only moderate mechanical strength and recoverability, as well as poor ionic conductivity and low operating voltage window. In this work, a type of ionogel electrolytes is reported on the basis of a dual-dynamic network composed of metal-ligand (Li+-PEO) coordination and hydrogen bonding. Impressively, the ionogel electrolytes exhibit high tensile fracture strength (0.96 MPa), stretchability (≈1847%) and electrochemical stability up to about −4 to 4 V. A novel all-in-one self-healable micro-supercapacitor prototype is proposed by adopting direct ink writing technique, whereas the electrode material is directly printed onto the ionogel film which acts as a flexible substrate and gel-electrolyte simultaneously. The maximum energy density of the all-in-one micro-supercapacitor reaches 81.88 μWh cm−2 at a power density of 0.75 mW cm−2. In the absence of external stimulus, the damaged micro-supercapacitor can achieve up to 98% self-healing efficiency after 2 min at room temperature. Our research provides new fundamental insights into the construction of stretchable and self-healable ionogels and offers guidelines for the design of integrated micro-supercapacitors to deliver better electrochemical performance.

Iron-manganese binary oxides (FeMnOx) can remove contaminants from aqueous solutions with high efficiency, and mesoporous silica (SBA-15) is widely used as a supporting material due to its large specific surface area and good stability. In this study, SBA-15 was used to support FeMnOx in the synthesis of a novel arsenic (As) adsorbent (FeMnOx/SBA-15), and its characteristics under different reaction conditions, such as pH, temperature, presence of competing ions, and humic acid, were tested. The results showed that the contaminant adsorption efficiency of the novel adsorbent was better than that of bare FeMnOx, as the addition of SBA-15 decreased the agglomeration effect of FeMnOx. Additionally, FeMnOx/SBA-15 underwent calcination to further enhance its performance. The state of iron and manganese in FeMnOx/SBA-15 and the corresponding arsenic removal efficiency were improved by calcination at 350 °C with an FeMnOx/SBA-15 mass fraction of approximately 45%. Almost 90% of As (50 mL, 5.0 mg L−1) could be removed by 0.2 g L−1 of FeMnOx/SBA-15 (mass ratio of 45% and calcination temperature of 350 °C). The FeMnOx/SBA-15 could regenerate and still be used after four consecutive cycles. The high As sorption capacity, ability to regenerate, and reusability of FeMnOx/SBA-15 confirmed that this adsorbent is promising for treating As-contaminated drinking water.

Background Paddy soil dissolved organic matter (DOM) represents a major hotspot for soil biogeochemistry, yet we know little about its chemodiversity let alone the microbial community that shapes it. Here, we leveraged ultrahigh-resolution mass spectrometry, amplicon, and metagenomic sequencing to characterize the molecular distribution of DOM and the taxonomic and functional microbial diversity in paddy soils across China. We hypothesized that variances in microbial community significantly associate with changes in soil DOM molecular composition. Results We report that both microbial and DOM profiles revealed geographic patterns that were associated with variation in mean monthly precipitation, mean annual temperature, and pH. DOM molecular diversity was significantly correlated with microbial taxonomic diversity. An increase in DOM molecules categorized as peptides, carbohydrates, and unsaturated aliphatics, and a decrease in those belonging to polyphenolics and polycyclic aromatics, significantly correlated with proportional changes in some of the microbial taxa, such as Syntrophobacterales, Thermoleophilia, Geobacter, Spirochaeta, Gaiella, and Defluviicoccus. DOM composition was also associated with the relative abundances of the microbial metabolic pathways, such as anaerobic carbon fixation, glycolysis, lignolysis, fermentation, and methanogenesis. Conclusions Our study demonstrates the continental-scale distribution of DOM is significantly correlated with the taxonomic profile and metabolic potential of the rice paddy microbiome. Abiotic factors that have a distinct effect on community structure can also influence the chemodiversity of DOM and vice versa. Deciphering these associations and the underlying mechanisms can precipitate understanding of the complex ecology of paddy soils, as well as help assess the effects of human activities on biogeochemistry and greenhouse gas emissions in paddy soils.

Titanium carbide (TiC) with excellent electrical conductivity, chemical and thermal stabilities has been recognized as one of the most promising electrocatalysts. A novel cathode, titanium carbide doped palladium/nickel foam (TiC-Pd/Ni foam), was synthesized via electroless deposition to improve the performance of Pd/Ni foam in electrocatlytic hydrodechlorination (ECH). TiC can be co-precipitated onto the surface of cathode during galvanic replacement reaction between Pd(II) solution and Ni foam. Both constant potential and constant current tests proved that TiC-Pd/Ni foam cathode performed remarkably higher activity for 2,4-dichlorobenzoic acid (2,4-DCBA) than Pd/Ni foam cathode, owing to the excellent conductivity of TiC and enhanced water dissociation over TiC-Pd/Ni foam cathode. Under the optimized reaction conditions of –0.85 V (vs Ag/AgCl), electrolyte of 10 mM and initial pH of 4, 99.8% of aqueous 2,4-DCBA (0.2 mM) was removed within 90 min. The removal process of the aqueous 2,4-DCBA obeyed first-order decay kinetic model. Over 86.3% of 2,4-DCBA can still be removed by TiC-Pd/Ni foam cathode in the fifth consecutive run within 120 min, which was much higher than that of Pd/Ni foam cathode (37.5%). Consequently, TiC-Pd/Ni foam cathode was a promising design for enhanced ECH activity and reduced operation cost.

This study is related to the removal of organics and other pollutants from drinking water using an integrated treatment system consisting of coagulation–sedimentation, ozonation and granular activated carbon (GAC)-enhanced sand filtration. Standard methods and instruments were employed to measure turbidity, chemical oxygen demand determined by using the permanganate method as permanganate index (CODMn), UV254, total organic carbon (TOC), ammonia and nitrite of raw and treated water under controlled laboratorial conditions. The experimental results demonstrated that the total removal rates of turbidity, CODMn, UV254 and TOC were in the range of 98–99.9, 21–71, 33–73 and 20–47%, respectively, in different units of the integrated treatment system. GAC-enhanced sand filtration significantly removed ammonia and nitrite, and the average removal efficiency was attained to 88 and 98%, respectively. In addition, most of the organic matter concentrations were observed to be reduced in GAC-enhanced sand filtration and only small molecular weight compounds were detected in the effluent. All these pollutant reductions were noticed in the upper 350 mm of the activated carbon column in GAC-enhanced sand filtration. The findings from this study suggest that the integrated treatment process can efficiently remove organics and other toxic pollutants from drinking water and can be a better alternative to conventional treatment.

Chlorella vulgaris , a marine microalgae strain adaptable to 0–50 g L −1 of salinity, was selected for studying the coupling system of saline wastewater treatment and lipid accumulation. The effect of total nitrogen (TN) concentration was investigated on algal growth, nutrients removal as well as lipid accumulation. The removal efficiencies of TN and total phosphorus (TP) were found to be 92.2–96.6% and over 99%, respectively, after a batch cultivation of 20 days. To illustrate the response of lipid accumulation to nutrients removal, C. vulgaris was further cultivated in the recycling experiment of tidal saline water within the photobioreactor. The lipid accumulation was triggered upon the almost depletion of nitrate ( −1 ), till the final highest lipid content of 40%. The nitrogen conversion in the sequence of nitrate, nitrite, and then to ammonium in the effluents was finally integrated with previous discussions on metabolic pathways of algal cell under nitrogen deficiency.

Anaerobic oxidation of methane (AOM) coupled to nitrite reduction is a novel AOM process that is mediated by denitrifying methanotrophs. To date, enrichments of these denitrifying methanotrophs have been confined to freshwater systems; however, the recent findings of 16S rRNA and pmoA gene sequences in marine sediments suggest a possible occurrence of AOM coupled to nitrite reduction in marine systems. In this research, a marine denitrifying methanotrophic culture was obtained after 20 months of enrichment. Activity testing and quantitative PCR (qPCR) analysis were then conducted and showed that the methane oxidation activity and the number of NC10 bacteria increased correlatively during the enrichment period. 16S rRNA gene sequencing indicated that only bacteria in group A of the NC10 phylum were enriched and responsible for the resulting methane oxidation activity, although a diverse community of NC10 bacteria was harbored in the inoculum. Fluorescence in situ hybridization showed that NC10 bacteria were dominant in the enrichment culture after 20 months. The effect of salinity on the marine denitrifying methanotrophic culture was investigated, and the apparent optimal salinity was 20.5‰, which suggested that halophilic bacterial AOM coupled to nitrite reduction was obtained. Moreover, the apparent substrate affinity coefficients of the halophilic denitrifying methanotrophs were determined to be 9.8 ± 2.2 μM for methane and 8.7 ± 1.5 μM for nitrite.

In this study, a novel composite adsorbent (HBC-Fe3O4-MnO2) was synthesized by combining honeycomb briquette cinders (HBC) with Fe3O4 and MnO2 through a co-precipitation process. The purpose was to make the best use of the oxidative property of MnO2 and the adsorptive ability of magnetic Fe3O4 for enhanced As(III) and As(V) removal from aqueous solutions. Experimental results showed that the adsorption capacity of As(III) was observed to be much higher than As(V). The maximum adsorption capacity (2.16 mg/g) was achieved for As(III) by using HBC-Fe3O4-MnO2 (3:2) as compared to HBC-Fe3O4-MnO2 (2:1) and HBC-Fe3O4-MnO2 (1:1). The experimental data of As(V) adsorption fitted well with the Langmuir isotherm model, whereas As(III) data was described perfectly by Freundlich model. The pseudo-second-order kinetic model was fitted well for the entire adsorption process of As(III) and As(V) suggesting that the adsorption is a rate-controlling step. Aqueous solution pH was found to greatly affect the adsorption behavior. Furthermore, co-ions including HCO3(-) and PO4(3-) exhibited greater influence on arsenic removal efficiency, whereas Cl(-), NO3(-), SO4(2-) were found to have negligible effects on arsenic removal. Five consecutive adsorption-regeneration cycles confirmed that the adsorbent could be reusable for successive arsenic treatment and can be used in real treatment applications.

Anaerobic oxidation of methane coupled to nitrite reduction (n-damo) plays an important role in global carbon and nitrogen cycles and also is a potential bioprocess in wastewater treatment. In this work, the effects of environmental conditions – temperature, pH and salinity – on the metabolic activity and growth rate of n-damo bacteria were investigated by short-term batch test and long-term bacterial incubation. Quantitative PCR and 16S rRNA and pmoA gene sequencing were applied to detect the microbial community in the long-term incubation. The results indicated that all the three environmental factors significantly affected the metabolic activity and growth rate of n-damo bacteria and the optimum temperature, pH and salinity were 35 °C, 7.6 and 0 g NaCl L⁻¹, respectively. Notably, salinity adaption of n-damo bacteria was first observed under salinity stress of 20 g NaCl L⁻¹. It's predicted that n-damo process might occur in saline environments and future work could focus on this.

Elevated concentration of arsenic in water supplies is detected worldwide and therefore becomes a global issue. Calcination process is known to increase the adsorbent hardness for its effective application in column-based treatment. In this study, magnetic honeycomb briquette cinders (MHBC) and its calcined products: MHBC(A) and MHBC(N) were employed for the adsorptive removal of As(III) in fixed-bed column. Characterizations revealed that the calcination at 1000 °C under nitrogen has significantly increased the adsorbent particles size; favored phase transformation and improved saturation magnetization (>20 emu g − 1 ). Additionally, the new iron silicate phase (Fe 2 SiO 4 ) in aqueous medium generated highly reactive iron oxide species (=FeOOH), which effectively bind As(III) from the influent water by ligand exchanges. In contrast, calcination under dynamic air drastically reduced the saturation magnetization ( − 1 ) and assisted to form segregated magnetite, quartz and hematite, as revealed in XRD patterns. The breakthrough curve of each column was compared with Thomas model and found that the model could be applied to estimate As(III) adsorption in fixed-bed column. Thomas model suggested parameters follow the order: MHBC(N) > MHBC > MHBC(A) and the maximum solid phase concentration ( q T ) was found to be about 56.07 mg g − 1 for MHBC(N). The column beds could be successfully regenerated using 200 bed volume of 10% NaOH solution. This study suggests that the selective calcination process need to be integrated with the adsorbent development process for the efficient removal of As(III) from contaminated water using column-based treatment.

Florfenicol (FF, C12H14Cl2FNO4S), an emerging halogenated organic contaminant of concern was effectively degraded in water by sulfidized nanoscale zerovalent iron (S-nZVI). Sulfidized nZVI (62.5 m2 g–1) that was prepared using a one-step method resulted in small Fe0/Fe-sulfide particles that were more stable against aggregation than unsulfidized nZVI (10.2 m2 g–1). No obvious removal of FF was observed by unsulfidized nZVI. S-nZVI degraded FF, having a surface area normalized reaction rate constant of 3.1 × 10–4 L m–2 min–1. The effects of the S/Fe molar ratio, initial FF concentration, initial pH, temperature, and water composition on the removal of FF by S-nZVI, and on the formation of reaction products, were systematically investigated. Both dechlorination and defluorination were observed, resulting in four degradation products (C12H15ClFNO4S, C12H16FNO4S, C12H17NO4S, and C12H17NO5S). High removal efficiencies of FF by S-nZVI were achieved in groundwater, river water, seawater, and wastewater. The reac...

Black carbon (BC) is considered to be a promising novel material for controlling organic contaminants due to its strong adsorption property, low production cost, and less secondary pollution. However, seldom systemic research was conducted to investigate adsorption-desorption characteristics and interaction mechanism between BC and nonylphenol (NP), one kind of endocrine-disrupting contaminants (EDCs) and persistent organic pollutants (POPs). Therefore, in the present study, adsorption characteristics of NP on two BCs (rice straw black carbon (RC) and fly ash carbon (FC)) involving adsorption isotherm, kinetics, effect of pH, as well as desorption kinetics, were investigated to explore the feasibility of BC for remediation of NP pollution in a water environment. Adsorption isotherm data showed that Q max was 61,889.21 ± 2777.68 and 6538.99 ± 606.72 mg/kg and n was 0.39 ± 0.037 and 0.55 ± 0.043 for RC and FC, respectively, suggesting the sorption capacity and nonlinearity of RC to NP is far higher than FC and indicating BC was an effective sorbent for NP pollution control, especially RC. The pH affected BC sorption capacity to NP by influencing the surface properties of BC and the NP speciation together. Desorption kinetics data indicated that more than 80% NP could not be released from both BCs, suggesting that BC could reduce NP releasing risk in a water environment evidently when BC is applied for NP pollution remediation.

Two biphenyl-degrading bacterial strains, SS1 and SS2, were isolated from polychlorinated biphenyl (PCB)-contaminated soil. They were identified as Rhodococcus ruber and Rhodococcus pyridinivorans based on the 16S rRNA gene sequence, as well as morphological, physiological and biochemical characteristics. SS1 and SS2 exhibited tolerance to 2000 and 3000 mg/L of biphenyl. And they could degrade 83.2 and 71.5% of 1300 mg/L biphenyl within 84 h, respectively. In the case of low-chlorinated PCB congeners, benzoate and 3-chlorobenzoate, the degradation activities of SS1 and SS2 were also significant. In addition, these two strains exhibited chemotactic response toward TCA-cycle intermediates, benzoate, biphenyl and 2-chlorobenzoate. This study indicated that, like the flagellated bacteria, non-flagellated Rhodococcus spp. might actively seek substrates through the process of chemotaxis once the substrates are depleted in their surroundings. Together, these data provide supporting evidence that SS1 and SS2 might be good candidates for restoring biphenyl/PCB-polluted environments.