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Waste activated sludge (WAS) has low biodegradability that restricts acidogenic fermentation (AF), thereby limiting the high-value volatile fatty acids (VFAs) production. This study investigated an alternative electrochemical pretreatment (EPT) approach that can facilitate AF of WAS and food waste (FW) and therefore enhance VFAs production. The results showed through introducing 50 % volatile solid basis of FW (containing massive chloride) into WAS, a 60-min EPT produced reactive chlorine species (RCS), which diffused into WAS-FW inner layers resulting in cell lysis, therefore significantly promoted and accelerated WAS-FW disintegration, contributing to more soluble and biodegradable dissolved organic matter (DOM). Then during the subsequent 15-day acidogenic co-fermentation (Co-AF), the residual RCS (approximate 5 mg Cl

Valorizing solid waste for heavy metal adsorption is highly desirable to avoid global natural resources depletion. In this study, we developed a new protocol to valorize Radix Astragali residue (one of the Chinese medicine residues) into a low-cost, chemically robust, and highly permeable (ca. 90%) amino-laced porous double-network hydrogel (NH

Benzophenone derivatives, including benzophenone-1 (C13H10O3, BP1), benzophenone-3 (C14H12O3, BP3) and benzophenone-8 (C14H12O4, BP8), that used as UV filters are currently viewed as emerging contaminants. Degradation behaviors on co-exposure benzophenone derivatives using UV-driven advanced oxidation processes under different aqueous environments are still unknown. In this study, the degradation behavior of mixed benzophenone derivatives via UV/H2O2 and UV/peroxydisulfate (PDS), in different water matrices (surface water, hydrolyzed urine and seawater) were systematically examined. In surface water, the attack of BP3 by hydroxyl radicals (HO∙) or carbonate radicals (CO3∙-) in UV/H2O2 can generate BP8, which was responsible for the relatively high degradation rate of BP3. Intermediates from BP3 and BP8 in UV/PDS were susceptible to CO3∙-, bringing inhibition of BP1 degradation. In hydrolyzed urine, Cl− was shown the negligible effect for benzophenone derivatives degradation due to low concentration of reactive chlorine species (RCS). Meanwhile, BP3 abatement was excessively inhibited during co-exposure pattern. In seawater, non-first-order kinetic behavior for BP3 and BP8 was found during UV/PDS treatment. Based on modeling, Br− was the sink for HO∙, and the co-existence of Br− and Cl− was the sink for SO4∙-. The cost-effective treatment toward target compounds removal in different water matrices was further evaluated using EE/O. In most cases, UV/H2O2 process is more economically competitive than UV/PDS process.

A broad bandgap and detrimental recombination of photoexcited h+-e− pairs are fatal deficiencies for using the g-C3N4 visible light water splitting. Herein, a sea-urchin-structure g-C3N4 (CNSC) with ∼2.0 eV bandgap was prepared using a hydrothermal strategy. It is important to note that CNSC can efficiently suppress h+-e− pair recombination and has a narrow bandgap which can utilize more visible light. Conventional g-C3N4 has a ∼2.7 eV bandgap and valence band (VB) potential of +1.83 V vs. NHE but the VB of CNSC is +1.55 V. As a result, CNSC does not create H2O2, which can passivate g-C3N4. Density functional theory (DFT) confirms that C N, C O, and OH groups in the CNSC shift the d-band centre of Pt closer to Fermi level, leading to better stabilization of adsorbate and higher catalytic performance. Photo-depositing Pt on the CNSC, 3 wt% Pt/CNSC produces H2 and O2 evolution rate (HER and OER) of 41.5 and 20.3 μmol g-1 h-1 (apparent quantum efficiency: 0.43% at 420 ± 10 nm), respectively, 30 times greater than HER of 2 wt% Pt/bulk g-C3N4 in overall water splitting under visible-light (λ ≥ 420 nm). This work provides an innovative approach to construct hierarchical nanostructure g-C3N4 with narrow bandgap and paves the pathway for development of water splitting photocatalysts.

A novel electrocatalytic system was developed to realize one-pot conversion of organic pollutants into liquid fuels such as methanol (CH3OH) and ethanol (C2H5OH). The process combines the catalytic oxidation of organic pollutants with electrocatalytic reduction of CO2. We first coupled the electrocatalytic process with SO4•−-based advanced oxidation processes (AOPs) for the degradation of 4-nitrophenol (4-NP) using a 3D-hexagonal Co3O4 anode. In this step, 4-NP was mineralized to CO2, and then the CO2 was converted to CH3OH and C2H5OH by electrocatalytic reduction using a flower-like CuO cathode. The experimental results show the destruction of 4-NP (60 mL, 10 mg/L) can be as high as 99%. In addition, the yields of CH3OH and C2H5OH were 98.29 μmol/L and 40.95 μmol/L, respectively, which represents a conversion of 41.8% of 4-NP into liquid fuels; the electron efficiency was 73.1%. In addition, we found that 3D-hexagonal arrays of Co3O4 with different morphologies can be obtained by adding different amounts of urea. We also investigated the formation mechanism of novel 3D-hexagonal Co3O4 arrays for the first time. A mechanism was proposed to explain the electrocatalytic steps involved in the conversion of 4-NP to CH3OH and C2H5OH and the synergetic effects between AOPs and electrocatalysis.

The complexity of sludge components and the heterogeneity of pyrolysis products make it challenging to trace char-volatile evolutions and interaction mechanisms during pyrolysis. Herein, we systematically dissected the solid-state reactions and volatile dynamic variations via in-situ infrared/mass spectral probes coupled signal amplification techniques. The identification of hidden reactions was further enhanced by comparing the discrepancies in the pyrolysis of three systems: raw sludge, sludge-extracted organics, and pseudo-components of organics. A three-stage sludge pyrolysis of bond cleavage (α = 0.2-0.5), intermediates diffusion (α = 0.5-0.7), and interface interaction (α = 0.7-0.8) was proposed through solid-state reaction tracing, and the pyrolysis reaction was found to be dominated by the first two stages. The generation of reactive intermediates accelerated the collision frequency between reactants, which increased the order of solid-state reactions and raised the energy barrier from 148 to 180-261-297 kJ/mol. The temperature-response sequence of the major pyrolysis volatiles was H

Oxcarbazepine (OXC) is ubiquitous in the aqueous environment. And due to its ecotoxicological effects and potential risks to human, an effective way to eliminate OXC from aqueous environment has aroused public concerns in recent years. Radical-based reactions have been shown to be an efficient way for OXC destruction, but the reactions of OXC with reactive oxygen species (ROS) and carbonate radical (CO3•−) are still unclear. In this study, we focused the degradation of OXC and ROS, CO3•− generation mechanism, and their roles in OXC degradation via UV and UV/H2O2. The triplet state of oxcarbazepine (3OXC∗) was found to play an important role in OXC degradation via UV. And hydroxyl radicals (•OH) and singlet oxygen (1O2) were found to be the dominant ROS in OXC degradation. Superoxide radical (O2•−) did not react with OXC directly, but it may react with intermediate byproducts. Generation of CO3•− played a positive role on OXC degradation for both UV and UV/H2O2. In addition to •OH, 3OXC* also contribute to CO3•− production. The second-order rate constants of OXC with •OH and CO3•− were 1.7 × 1010 M−1 s−1 and 8.6 × 107 M−1 s−1, respectively. Potential OXC degradation mechanisms by •OH were proposed and included hydroxylation, α-ketol rearrangement, and benzylic acid rearrangement. Compared with non-selective •OH, the reactions involving CO3•− are mainly electron transfer and hydrogen abstraction. And the acute toxicity of OXC was lower after UV/H2O2 and UV/H2O2/HCO3− treatments, which was confirmed by luminescent bacterial assay (Vibrio fischeri bacterium).

Phenicol antibiotics (PABs) degradation by UV/H2O2 is important because we need to determine the reduction in toxicity and disinfection byproducts for post-chlorine. In this study, the degradation of PABs, including florfenicol (FLO), chloramphenicol (CAP) and thiamphenicol (THA), was examined. The pseudo-first order degradation rate constants of PABs were 3 times higher in ultrapure water (UW) than that in synthetic wastewater (SW) for these conditions: [PABs]0 = 1 μM, [H2O2] = 0.1 mM, and I0 = 1.985 × 10−6 E L−1 s−1. Fulvic acid (FA) and HCO3– inhibited PABs degradation, Cl− and NO3– concentrations of up to 5 mM and 10 mM had a negligible impact. The impact of water matrix on PABs degradation was successfully predicted using pseudo-steady-state kinetic model. The degradation of PABs was triggered via hydroxylation and/or hydrogen abstraction. The treatment of PABs via UV/H2O2 could decrease their antimicrobial properties, while the byproducts of FLO and THA showed higher acute toxicity in Vibrio fischeri. In addition, two identification products (TP-276 and TP-354) of FLO had higher ecotoxicity toxicity (using ECOSAR) in fish, daphnid and green algae. The trichloromethane formation potential (TCMFP) for PABs with post-chlorination in UW and SW can be reduced after UV/H2O2 compared to UV, and is related to the corresponding decrease of dissolved organic carbon (DOC).

Although noble metal electrocatalysts are highly efficient in the dehalogenation of halogenated antibiotics, the prohibitive cost hinders their practical applications. In this study, a cobalt-phosphorous/oxide (Co P/O) composite prepared via a one-step electrodeposition was for the first time applied in electroreductive dechlorination of halogenated antibiotics (HA), including chloramphenicol (CAP), florfenicol (FLO) and thiamphenicol (TAP). Co P/O had a higher FLO dechlorination efficiency (91%) than Pd/C (69.3%) (t = 60 min, C0 = 20 mg L−1, applied voltage of −1.2 V vs. saturated calomel electrode (SCE)). Furthermore, the dechlorination efficiencies of Co P/O for CAP and TAP reached to 98.7 and 74.2%, respectively. The electron spin resonance and in situ Raman characterizations confirmed that atomic H* was produced via the Co P and the formation of Co Cl bonds occurred on the Co O in Co P/O. The Co Cl bond formation could trap HA molecules onto Co P/O and weaken the C Cl bond strength. The synergistic effect of H* attack and Co Cl bond was responsible for the high dechlorination efficiency. This study offers new insights into the interface mechanism of electroreductive dehalogenation process, and shows a great potential for the remediation of halogenated antibiotics contaminated wastewater.

While the widely used β-lactam antibiotics, such as cephalosporins, are known to be susceptible to oxidation by sulfate radical (SO4-), comprehensive study about SO4--induced oxidation of cephalosporins is still limited, such as the impact of water matrices, and the structure and antibacterial activity of transformation products. Herein, the oxidation of cefalexin (CFX), a most frequently detected cephalosporin, was systematically investigated by thermally activated persulfate (PS). CFX oxidation followed pseudo-first-order kinetics, and SO4- dominantly contributed to the overall oxidation of CFX. The impact of water matrices, such as Cl-, HCO3- and natural organic matter, on CFX degradation was predicted using a pseudo-steady-state kinetic model. The secondary reactive species, such as chlorine and carbonate radicals, were found to contribute to CFX degradation. Product analysis indicated oxidation of CFX to six products (molecular weight of 363), with two stereoisomeric sulfoxides as the primary oxidation products. It was thus suggested that the primary amine on the side chain, and the thioether sulfur and double bond on the six-membered ring were the reactive sites of CFX towards SO4- oxidation. Antibacterial activity assessment showed that the biological activity of CFX solution was significantly diminished after treatment by the thermally activated PS.

In this study, a novel adsorbent was designed and synthesized via intercalation of sodium dodecyl sulfate (SDS) in the interlayer, and subsequent grafting of acrylamide (AM) on the layer of layered double hydroxides (LDH) (named as AM/SDS-LDH), and applied for congo red (CR) removal. The morphological structure, wettability and physicochemical properties of the adsorbents were thoroughly characterized using SEM, EDS, N2-adsorption/desorption isotherm, static contact angle, XRD and FTIR. Results elucidated that SDS and AM were successfully introduced into the interlayer and onto the layer of LDH, respectively. Adsorption experimental results suggested that the maximum adsorption capacities of CR on SDS-LDH and AM/SDS-LDH at pH 5.0 and 293 K were 714.29 and 1118.78 mg/g, respectively, which were much higher than that of CR on LDH (588.24 mg/g). Based on the BET, XRD and FTIR analysis, the higher adsorption capacity of AM/SDS-LDH was mainly attributed to high surface area, large basal spacing as well as the abundant NH2 groups. The experimental data can be well fitted by pseudo-second-order kinetic and Langmuir isotherm models. Thermodynamic parameters indicated the adsorption process was favorable under the higher temperature condition. The synergistic effect existed during the adsorption process of CR onto AM/SDS-LDH, including the electrostatic interactions, anion exchange and hydrophobic-hydrophobic interactions. Overall, this study provided a strategy for design and fabrication of highly efficient adsorbents.

In this study, nanoscale zero-valent iron (nZVI) with a considerably high surface area (182.97 m2·g−1) and featured morphology of chain structure has been synthesized and well characterized. The as-prepared nZVI on can totally remove Cr(VI) under anoxic condition after 20 min reaction, whereas only 43% of Cr(VI) was removed after 60 min reaction under oxic condition. Noteworthily, the nZVI exhibits excellent removal capacity of Cr(VI) (123.85 mg/g) and fast removal rate (0.017 g·mg−1·min−1), much better than those reported in the literatures except for that reported by Li et al. (2008) [1] . Experimental results have confirmed that only FeCr2O4 with low compactness was generated under anoxic and acidic conditions in the new process. And it is evident that the formation of the passivation layer which contains oxides and hydroxides (or (oxy)hydroxides) of iron and chromium were well hindered. Furthermore, the as-prepared nZVI has shown fast removal of traced Cr(VI) from the Cr-spiked drinking water or actual Cr-contaminated lake water. Accordingly, we proposed a new reaction process of Cr(VI) reduction by nZVI under anoxic condition. And we firstly make clear the detailed process of Cr(VI) removal by the as-prepared nZVI via X-ray photoelectron spectrometer (XPS) analysis in time scale. Meanwhile, the excellent Cr(VI) removal performance of the as-prepared nZVI could be attributed to (i) the high surface area, (ii) large quantity of active sites of nZVI, and (iii) fast electron transfer from the nZVI/FeCr2O4 to Cr(VI). The present work not only provides the potential materials for the application to the rapid and high-efficient removal of Cr(VI) from aqueous solution, but also proposed a new avenue for hindering the passivation of Fe0. And a detailed mechanism of the Cr(VI) removal by nZVI was proposed for the first time.

High adsorption capacity, fast adsorption kinetics, good reusability and low cost are highly demanded for adsorbents used in practical adsorption process. In this study, a porous double network Jute/Polyacrylic acid (Jute/PAA) gel was prepared using simple free-radical polymerization of acrylic acid in Jute aqueous solution. The high permeability of Jute/PAA hydrogel with about 80 wt% water made internal adsorption sites fully expose to metal ions. The Jute/PAA gel adsorbent could efficiently adsorb heavy metals in melting wastewater, especially Cd2+ and Pb2+. The adsorbent showed very high adsorption capacities of 401.7 mg/g for Cd2+ and 542.9 mg/g for Pb2+. Moreover, the adsorption equilibrium reached within only 10 min for 40 mg/L of Cd2+ and Pb2+ using 1 g/L adsorbent. Meanwhile, the removal efficiencies reached 81.0% for Pb (C0 = 3.825 mg/L), 79.3% for Cd (C0 = 6.075 mg/L), 83.4% for Cu (C0 = 9.325 mg/L), 29.8% for Zn (C0 = 188.6 mg/L), 22.3% for Mn (C0 = 17.05 mg/L), 96.2% for Cr (C0 = 0.25 mg/L) and 99.8% for Fe (C0 = 9.75 mg/L) in melting wastewater using 1 g/L adsorbent in 2 h. In particular, the concentrations of Pb, Cd and Cr decreased below 0.001 mg/L using 4 g/L adsorbent. In the fixed-bed column experiments, the treatment volume of melting wastewater reached 2900 BV (32.8 L) only producing 50 BV (565 mL) eluent. This work develops a highly practical adsorption process based on hydrogel adsorbents for the removal of heavy metals in actual wastewater.

To solve serious energy and environmental crises caused by rapid industrial development, the formation of Z-scheme heterostructured photocatalysts is a promising approach for efficient and scalable H2 production from water splitting due to wide absorption range, high charge-separation efficiency and strong redox ability of the Z-scheme heterostructured photocatalysts. In this study, we combined the MOFs of NH2-MIL-125(Ti) with g-C3N4 functionalized by benzoic acid (CFB) to synthesize a novel composite catalyst of CFB/NH2-MIL-125(Ti) (CFBM) by covalent bonds for the first time. The benzoic acid in the CFBM acts as electron mediator to well separate photogenerated electrons and holes, leading to excellent photocatalytic performance of photocatalytic hydrogen generation from water splitting under visible light irradiation. Experimental results show that the H2 production rate of the 10CFBM is 1.123 mmol·h−1·g−1, which is about 6 times of the NH2-MIL-125(Ti). Meanwhile, the simple physical mixture of NH2-MIL-125(Ti) with 10 wt% g-C3N4 and the 10wt%g-C3N4/MOFs heterostructured catalyst all show much smaller H2 evolution rate and worse stability than that of the 10CFBM. Finally, we proposed a possible mechanism to well explain the improved photocatalytic performance of the Z-scheme photocatalytic system based on the results of different characterizations. The present work gives a good example to develop a novel Z-scheme heterostructured system with good stability and high photocatalytic activity for H2 evolution and puts forward a new synthetic strategy to prepare metal-free semiconductor/MOFs formed by covalent bonds.

The adsorption behavior of arsenic (As) on specific crystalline phases of manganese dioxide (MnO2) remains unclear. In this study, we evaluated the ability of α-MnO2 nanofibers (MO-2) to remove both arsenite (As(III)) and arsenate (As(V)), using experimental and computational methods. The maximum adsorption capacity values of As(III) and As(V) on MO-2 were 117.72 and 60.19 mg/g, respectively, which is higher than values reported for α-MnO2, β-MnO2 and γ-MnO2. In particular, because MO-2 has much higher adsorption capacity for As(III) than As(V), it can be effectively applied in removal of As(III) from groundwater, and a pre-oxidation process is not required. Fixed-bed tests showed that about 800 mL As(III)- or 480 mL As(V)-contaminated water could be treated before breakthrough, and MO-2 can be effectively regenerated using only 12 mL of eluent. This means we can concentrate the As(III) and As(V) by factors of 66.6 and 40.0, respectively. According to density functional theory (DFT) calculations, As(III) and As(V) form stable complexes on (1 0 0) and (1 1 0) of α-MnO2. Moreover, the surface complexes of As(III) and As(V) on (1 0 0) are more stable than (1 1 0). Electron transfer from As(III) on (1 0 0) is greater than (1 1 0). These phenomenon are may due to the fact that (1 0 0) has lower surface energy than (1 1 0). Partial density of state (PDOS) analysis further confirmed that As(III, V) are chemisorbed on MO-2, which agreed with the Dubinin-Radushkevich model.

It is attractive to photocatalytically purify wastewater and simultaneously convert solar energy into clean hydrogen energy. However, it is still a challenge owing to the relatively low photocatalytic efficiency of photocatalysts. In this study, we synthesized a molybdenum disulfide (MoS 2 ) quantum dot-decorated 3D nanoarchitecture (MoS 2 QDs) of indium zinc sulfide (ZnIn 2 S 4 ) and reduced grapheme oxide (MoS 2 QDs@ZnIn 2 S 4 @RGO) photocatalyst using a simple solvothermal method. The RGO promotes the electron transfer, and the highly dispersed MoS 2 QDs provides numerous catalytic sites. The photocatalytic purification of rhodamine B (RhB), eosin Y (EY), fulvic acid (FA), methylene blue (MB) and p -nitrophenol (PNP) in simulated wastewaters were further tested. The degradation efficiencies and TOC removal were 91% and 75% for PNP, 92.2% and 72% for FA, 98.5% and 80% for MB, 98.6% and 84% for EY, and 98.8% and 88% for RhB, respectively (C organics = 20 mg/L, C catalyst = 1.25 g/L, t = 12 h, I light = 3.36 × 10 −5 E L −1 s −1 ). Among these tests, the highest hydrogen production was achieved (45 μmol) during RhB degradation. Both experimental and calculational results prove that lower LUMO (lowest unoccupied molecular orbit) level of organic molecules was available for transferring electrons to catalysts, resulting in more efficient hydrogen production. Significantly, the removal efficiencies of natural organic substances in actual river water reached 76.3–98.4%, and COD reduced from 32 to 16 mg/L with 13.8 μmol H 2 production after 12 h.

In this work, we investigated the abatement of highly concentrated 1H-Benzotriazole (BTA) in aqueous solution by ozonation. Focusing on the COD removal and BTA degradation, the effects of different operational factors were explored, including different initial BTA concentrations (100–1000 mg/L), ozone dosages (16–48 mg/min) and initial pH values (3–11). It was found that the degradation of BTA was obviously affected by the initial concentration of BTA, pH value and O3 dosage. And the optimized pH value was observed at 11. The increasing of ozone dosage and the pH value would accelerate the degradation efficiency of BTA and COD removal, while the increasing of initial BTA concentration would hamper this process. Based on the effects of ozone dosage, initial BTA concentration and initial pH value, a kinetic model was established with the function of C = C0exp(−8.68QO32.4997C0−2.1262[OH−]0.0444t).

Hydrophilic poly(2-hydroxyethyl methacrylate) (PHEMA) brushes were modified onto the surface of ion-imprinted polymers (IIPs) via addition-fragmentation chain transfer (RAFT) polymerization. Four different grafting densities (1.43, 1.31, 1.17 and 1.06chains/nm2) of IIPs were obtained, revealed by analysis using gel permeation chromatograph (GPC) and Brunauer-Emmett-Teller (BET). All the grafted IIPs had good anti-interference properties compared to the ungrafted IIPs, although the adsorption capacity of the ungrafted IIPs was higher than that of grafted IIPs in pure water. Among them, the grafted IIP3, with a grafting density of β=1.17chains/nm2, exhibited superior anti-interference ability in silica and polymer flocculant simulated wastewater; moreover, it remained steady after 10 adsorption-desorption cycles. SEM-EDX and XPS data revealed anti-interference and anti-blockage mechanisms in which hydrophilic PHEMA brushes could effectively adhere to fine particles and flocculants through Van der Waals force interactions, which make the imprinted cavities well protected in a complex wastewater environment. Moreover, these grafted IIPs exhibit similar adsorption rate constants that are approximately 2 times greater than those of ungrafted IIPs, indicating that the PHEMA brushes increased the accessibility to Li(I) due to hydrophilic modification.

In this work, we report a systematic study of the relationship between photocatalytic properties of hydrogen evolution and structures and morphologies of g-C 3 N 4 prepared by different precursors (urea, melamine and dicyandiamide). The photocatalytic performances of H 2 production are affected by the method and degree of polymerization, the degree of protonation, and the morphology of g-C 3 N 4 prepared by different precursors. Furthermore, a novel metal-free N-GQDs/g-C 3 N 4 catalyst was designed and synthesized, which shows much better photocatalytic activity for H 2 evolution from water splitting than that of g-C 3 N 4 due to the unique and multiple roles of N-GQDs. A mechanism is put forth to explain the roles of N-GQDs and the detailed enhancement of photocatalytic performance of the N-GQDs/g-C 3 N 4 .

In this work, we reported a versatile and environmental-friendly mixed-solvent refluxing method to prepare MoS 2 nanosheets with few layers by exfoliation of bulk MoS 2 for the first time. The optimal synthetic conditions, including refluxing temperature, time and the volume ration of ethanol/water, were investigated according to the results of photocatalytic H 2 evolution from water splitting. The results show that the optimal conditions involve refluxing in 30% ethanol/water solution at 80 °C for 3 h. And the as-prepared MoS 2 nanosheets show much better photocatalytic properties than bulk MoS 2 . The rate of photocatalytic H 2 evolution is 176.7 μmol g −1 h −1 over the MoS 2 nanosheets synthesized under the optimal conditions, whereas the rate of H 2 production is only 21.8 μmol g −1 h −1 over the bulk MoS 2 . In addition, some characterization studies demonstrate the MoS 2 nanosheets have been successfully prepared by using the mixed-solvent refluxing method. The present work opens a new avenue to obtain two-dimensional nanosheets with single or few layers, such as the layered transition metal dichalcogenides.

The mechanisms of arsenic poisoning on MoO3- and WO3-doped V2O5/TiO2 catalysts are studied and the poisoning resistance effect of MoO3 are revealed. The arsenic at certain amount (above 10% of arsenic from XPS) decreases the surface area and the number of active sites where reduction takes place. From the results of DRIFTS and DFT, arsenic lowers the surface acidity by decreasing the quantity of Lewis acid sites and the stability of Bronsted acid sites. We also found newly formed As–OH groups of poisoned catalysts (at 1440 cm−1) have quite low activity at high temperature. MoO3 provides better activity on poisoned catalysts than WO3 does on V2O5/TiO2 catalysts. This may be due to the good dispersion of MoO3 on the support. The reactivity of surface W–O–W and W = O groups is considerably lower than the corresponding Mo–O–Mo and Mo = O groups from the DFT calculations models. This could be one of the explanations on the decrease of surface acidity of poisoned catalysts.

Novel heterostructured composite of few layered WS 2 -Bi 2 WO 6 /Bi 3.84 W 0.16 O 6.24 has been synthesized via a facile hydrothermal method for the first time. The obtained catalysts were systematically characterized by X-ray diffraction (XRD), SEM, TEM, EDS, Raman spectroscopy, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) to certify the existence of WS 2 with a few-layered structure among the heterostructured composite, and to illuminate the relationship of its performance and the structural features. Among the as-prepared catalysts, the few layered WS 2 -Bi 2 WO 6 /Bi 3.84 W 0.16 O 6.24 composite show the best photocatalytic degradation of RhB under visible light irradiation. The enhanced photocatalytic performance of the heterostructured few layered WS 2 -Bi 2 WO 6 /Bi 3.84 W 0.16 O 6.24 composite is attributed to the two-dimensional structure of WS 2 with special properties and the matching energy band structure for efficient separation of photogenerated electron–hole pairs. The formation mechanism and photocatalytic mechanism were proposed. The present work firstly combined layered TMDs with composites to prepare ternary heterostructured catalysts, which provide new ideas for obtaining novel layered TMDs-based composites with excellent performance.

This paper reports on the development of macroporous flow-through anodes. The anodes comprised an enhanced TiO2 nanotube array (ENTA) that was grown on three macroporous titanium substrates (MP-Ti) with nominal pore sizes of 10, 20, and 50 µm. The ENTA was then covered with SnO2-Sb2O3. We refer to this anode as the MP-Ti-ENTA/SnO2-Sb2O3 anode. The morphology, pore structure, and electrochemical properties of the anode were characterized. Compared with the traditional NTA layer, we found that the MP-Ti-ENTA/SnO2-Sb2O3 anode has a service lifetime that was 1.56 times larger than that of MP-Ti-NTA/SnO2-Sb2O3. We used 2-methyl-4-isothiazolin-3-one (MIT), a common biocide, as the target pollutant. We evaluated the impact of the operating parameters on energy efficiency and the oxidation rate of MIT. Furthermore, the apparent rate constants were 0.38, 1.63, and 1.24 min−1 for the 10, 20, and 50 μm nominal pore sizes of the MP-Ti substrates, respectively, demonstrating the different coating–loading mechanisms for the porous substrate. We found that hydroxyl radicals were the dominant species in the MIT oxidation in the HO radical scavenging experiments. The radical and nonradical oxidation contributions to the MIT degradation for different current densities were quantitatively determined as 72.1%–74.8% and 25.2%–27.9%, respectively. Finally, we summarized the oxidation performance for MIT destruction for (1) the published literature on various advanced oxidation technologies, (2) the published literature on various anodes, and (3) our flow-by and -through anodes. Accordingly, we found that our flow-through anode has a much lower electrical efficiency per order value (0.58 kWh m−3) than the flow-by anodes (6.85 kWh m−3).

Microbial fuel cells (MFCs) exhibit great potential for simultaneous wastewater treatment and energy recovery. However, sluggish cathodic oxygen reduction reaction (ORR) and expensive catalyst cost greatly retard further developments of MFCs. Herein, three-dimensional electrode interface was assembled from reduced graphene oxide nanosheets and carbon nanotubes (rGO@CNTs) through one-step electrodeposition method, and high electricity output performance of MFCs was obtained. To be noted, one-dimensional pristine CNTs could restrain the rGO stacking and enhance the electrode conductivity, and two-dimensional rGO sheets can prevent the bundling of CNTs. Furthermore, a certain amount of oxygen containing functional groups on rGO surface guarantees sufficient active sites and adequate conductivity. Compared with pure rGO and commercial Pt/C catalyst, the as-prepared rGO@CNTs electrode exhibits a superior ORR electrocatalytic performance (high catalytic activity and superior durability). In addition, being applied as sensitive films on MFC cathode, a high power density of 378.3 mW m−2 was achieved, which far prevails over commercial Pt/C catalyst (240.1 mW m−2) and pure rGO (84.6 mW m−2). This work develops a simple and low-cost modification method to construct high-performance catalytic electrode in bioelectrochemical systems.

The deactivation of catalysts by potassium and the promotion of cerium on MnO x /TiO 2 for selective catalytic reduction (SCR) of NO with NH 3 are investigated by both experiments and DFT calculations. Catalyst poisoning by K is due to the decrease of surface acidity, the loss of reducibility and the improvement of stable nitrite/nitrate species. When the catalyst is modified by CeO 2 , SCR activities of both fresh and poisoned catalysts are improved. Cerium provides new Lewis acid sites for NH 3 adsorption, which does not seem to be influenced by K. The Ce 4f orbitals of poisoned surfaces are nearly unaffected, which preserve reducibility of catalyst for NH 3 activation. Stable, inactive nitrite species do not build up and the reactive nitrate species are still present on the surface. These advantages can be attributed to the unique active sites, the [–O–Ce–O–Mn–O–] units . These active sites induce the movement of alkali metals to assemble together, leaving more surface active sites for SCR reaction.

Schwertmannite was incorporated onto graphene oxide to form nanocomposites (GO-SCH) to serve as an adsorbent for Sb(V) removal. A synergistic effect on Sb(V) uptake was observed for the composite adsorbent. A maximum Sb(V) adsorption capacity of 158.6 mg Sb(V)/g of GO-SCH at an equilibrium Sb(V) concentration of 8.0 mg/L at pH 7.0 was obtained. This capacity is superior to either GO or SCH alone. The effect of contact time, solution pH and co-existing competitive anions on Sb(V) uptake by GO-SCH was evaluated. External mass transfer governed the Sb(V) uptake kinetics within 1 h. After 1 h, intraparticle diffusion gradually became predominant. Common co-existing anions at their natural environmental concentrations had little effect on the performance of GO-SCH. Sb(V) in spiked tap water (100 mu g/L), simulated river water (6400 mu g/L), and acid mine drainage (50,000 mu g/L) was adsorbed by GO-SCH to well below the regulation levels for these waters. XRD and SEM analyses showed that SCH was well incorporated among GO platelets and highly dispersed on the GO carrier's surface. FTIR and Raman spectra showed that both SCH and GO surfaces in the composites contribute to Sb(V) removal and SCH was the main active phase. This was also confirmed by XPS Fe 2p spectra. Sb 3d(3/2) XPS spectra indicated that no surface precipitation or reduction of Sb(V) to Sb(III) occurred. Deconvolution of C Is XPS spectra and Boehm titration indicated the surface carboxyl, lactonic and phenolic hydroxyl groups of GO also contribute to Sb(V) removal. The outstanding Sb(V) uptake ability of GO-SCH suggests it is a promising adsorbent for antimony removal from contaminated water. (C) 2015 Elsevier B.V. All rights reserved.

Hierarchically mesostructured MIL-101 metal–organic frameworks (MOFs) were synthesized using anhydrous sodium acetate or hydrofluoric acid as a mineralizing agent and cetyltrimethylammonium bromide (CTAB) as a structure-directing agent. These new materials were then used to adsorb and remove the anionic dye methyl orange (MO) and the cationic dye methylene blue (MB) from contaminated water. The adsorption performance was systematically investigated and discussed. Experimental results revealed that the amount of MB adsorbed on MIL-101 that was prepared using sodium acetate is about 3.2 times the amount adsorbed on MIL-101 prepared using hydrofluoric acid, but quantities of adsorbed MO by the two adsorbents were nearly the same. Adsorbents synthesized with higher CTAB content had a higher content of the meso- and macro-scale pores, which favored the MB adsorption but impeded the MO adsorption. Dye adsorption is partially governed by the electrostatic interaction between the dye and the adsorbent, because the mineralizing agent can vary the charge carried by framework in a dye solution. The MB and MO adsorption kinetics followed a pseudo-second-order model, and the equilibrium dye adsorption data provided a good Langmuir model.

Deactivation of alkali metals and arsenic and regeneration methods are studied on commercial V 2 O 5 –WO 3 /TiO 2 for the SCR reaction using experiments and DFT calculations. The poisoning of alkali metals is found to decrease the amount of Bronsted acid sites and the reducibility of active V 5+ sites. Arsenic decreases the amount of Lewis acid sites and the stability of Bronsted acid sites and increases N 2 O formation. After the catalysts are poisoned by both alkali metals and arsenic, the activity and N 2 selectivity are significantly suppressed. Diluted H 2 SO 4 effectively removes alkali metals from the poisoned catalysts. Half of the amount of arsenic can be removed using a 4% H 2 O 2 solution; however, some V 2 O 5 and surface sulfates are also eliminated from the catalysts. The activity of the regenerated catalysts is almost recovered at high temperatures. From the DFT results on the V 2 O 5 /TiO 2 (0 0 1) plane, potassium and arsenic significantly alter the electronic structures of the V orbitals and broaden the band gap of the models. Interactions between potassium and arsenic are also found. Potassium covers the active sites of the models that are constructed by V 2 O 5 and As 2 O 5 , which further decreases the number of acid sites. Potassium causes V and As orbitals to move to lower energies and inhibits the reactivity of the model.

This paper is concerned with a non-fragile guaranteed cost control problem for a class of uncertain switched fuzzy systems which are described by switched Takagi–Sugeno (T–S) fuzzy models. By employing the generalized multiple Lyapunov functions method, we present a sufficient condition to guarantee the closed-loop system asymptotically stable and possess an upper bound of the non-fragile guaranteed cost function. Meanwhile, a non-fragile state feedback control law and a switching law are designed. Moreover, an optimization problem, in which the minimal non-fragile guaranteed cost can be obtained, is solved. Finally, a simulation example is given to verify the feasibility and effectiveness of the proposed method.

The interactions of several spiral waves with different independent rotation frequencies are studied in a model of two-dimensional complex Ginzburg-Laudau equation. We find a general coexistence phenomenon, non-local non-phase-locking-invasion coexistence, that is, the non-slowest spiral wave call survive and not be killed by the fastest spiral wave as it is insulated from the fastest one with the sacrifice of the slowest one, which stays in the spatial position between the fastest spiral and the non-slowest one. Both the parameter non-monotonicity and the non-phase-locking invasion between the fastest and the slowest spiral waves play key roles in this phenomenon. Importantly, the results could give a general idea for extensively observed coexistence of spiral waves in various inhomogeneous circumstances. (C) 2007 Elsevier Ltd. All rights reserved.

It is well known that one of key features of spiral waves in complex-oscillatory media is the appearance of synchronization defect lines, across which the phase of the oscillation changes by multiplies of 2 pi. In this Letter, we report the appearance of synchronization defect lines in target waves in complex-oscillatory media by studying a model of two-dimensional Rossler reaction-diffusion system subject to an appropriate periodic force in a small region of the center of domain. The geometric structure and stability of the defect lines are studied. (c) 2007 Elsevier B.V. All rights reserved.