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• A state Z-scheme Cu 2 O/Bi/Bi 2 MoO 6 heterojunction was first synthesized. • The Cu 2 O/Bi/Bi 2 MoO 6 displayed excellent removal activity in sulfadiazine and Ni(II). • The Z-scheme structure, SPR effect contributed to the excellent photocatalytic activity. • Theoretical calculation expressed electronic structure and visible light harvesting. Environmental problem on the coexistence of organic pollutants and heavy metals in surface waters has become increasingly serious. Few relative researches have focused on their simultaneous decontamination. Herein, a ternary plasmonic Z-scheme Cu 2 O/Bi/Bi 2 MoO 6 heterojunction was synthesized via two-step route followed by a wet-impregnation, where Bi spheres coupled with Cu 2 O particles were anchored on the surface of Bi 2 MoO 6 with hollow microflower spheres. The composites were characterized via various measurements. The excellent photocatalytic activity of Cu 2 O/Bi/Bi 2 MoO 6 displayed in single sulfadiazine (SDZ) oxidation or Ni(II) reduction, and their simultaneous removal. The degradation pathway for SDZ was investigated via LC–MS and Gaussian theory. DFT and FDTD calculations confirmed the electronic structural characteristics in the Cu 2 O/Bi/Bi 2 MoO 6 heterostructure and the induced electric field enhancement around nearly touching Bi spheres. A possible photodegradation mechanism of the as-prepared photocatalyst was elucidated via combining scavenger experiments with EPR technique. The results suggested h+, •O 2 − and •OH all participated in SDZ oxidation, which verified that Z-Scheme electron transfer was major manner in Cu 2 O/Bi/Bi 2 MoO 6 , while •O 2 − and e−acted on Ni(II) reduction. The improved photocatalytic activity of Cu 2 O/Bi/Bi 2 MoO 6 could be ascribed to the unique Z-scheme electron transfer among Cu 2 O, Bi and Bi 2 MoO 6 , particularly SPR and local electric field near Bi spheres. [ABSTRACT FROM AUTHOR]

It is important to establish an available analytical method for polycyclic aromatic hydrocarbons (PAHs), nitrated PAHs (nitro-PAHs), oxygenated forms of PAHs (oxy-PAHs), and hydroxy-PAHs (OH-PAHs) in sediment samples due to the fact that they co-exist in various environmental mediates, particularly in sediment. In this study, an analytical method has been developed and validated for the quantification of PAHs, nitro-PAHs, oxy-PAHs, and OH-PAHs in sediment samples. The sediment samples were extracted by accelerated solvent extraction and cleaned up with SPE alumina-n combining with aminopropyl cartridges. The extracts were further fractionated by using different solvents. The fractionated extracts were analyzed via gas chromatography of single and triple quadrupole mass spectrometry in the electron ionization and negative ion chemical ionization with selective ion monitoring and selective reaction monitoring mode and liquid chromatography-triple quadrupole mass spectrometry. Each group of analytes was determined by different instrument modes such as GC-EI-SIM for PAHs, GC-NICI-SRM for nitro-PAHs, GC-EI-SRM for the oxy-PAHs and LC-ESI-MS/MS for OH-PAHs. A total of 44 analytes (16 PAHs, 14 nitro-PAHs, 9 oxy-PAHs, and 5 OH-PAHs) and 6 deuterated surrogates were performed. Most of recovery percentage varied from 52.8% up to 114.1% for the targeted analytes verified at three concentration levels (100 ng/g, 400 ng/g and 1000 ng/g for PAHs and 10 ng/g, 50 ng/g and 400 ng/g for their derivatives). The repeatability determined by the relative standard deviation percentage of triplicate trials was less than 10% for most analytes. The limit of detection ranged from 0.01 to 0.02 ng/g for PAHs, 0.002–0.067 ng/g for nitro-PAHs, 0.01–0.1 ng/g for oxy-PAHs, and 0.003–0.006 ng/g for OH-PAHs. Most of the compounds were detectable in the sediments collected from a local River, which illustrates the developed method could be a practical and suitable technique for detection of PAHs and their derivatives in real sediment samples. Image 1 • Total of 44 PAHs and their derivatives were determined in spiked sediment with recovery rate ranged from 52.8%–114.1%. • Alumina-n and aminopropyl cartridges were packed for separation in the first time. • The proposed analytical method was proved to be practical and suitable for detection of PAHs and their derivatives. •. The PAH derivatives was detected at two magnitude orders lower than parent PAHs. [ABSTRACT FROM AUTHOR]

A photodegradation technology based on the combination of ultraviolet radiation with H 2 O 2 (UV/H 2 O 2) for degrading tri(chloroisopropyl) phosphate (TCPP) was developed. In ultrapure water, a pseudo-first order reaction was observed, and the degradation rate constant reached 0.0035 min−1 (R2 = 0.9871) for 5 mg L−1 TCPP using 250 W UV light irradiation with 50 mg L−1 H 2 O 2. In detail, the yield rates of Cl− and PO 4 3− reached 0.19 mg L−1 and 0.58 mg L−1, respectively. The total organic carbon (TOC) removal rate was 43.02%. The pH value of the TCPP solution after the reaction was 3.46. The mass spectrometric detection data showed a partial transformation of TCPP into a series of hydroxylated and dechlorinated products. Based on the luminescent bacteria experimental data, the toxicity of TCPP products increased obviously as the reaction proceeded. In conclusion, degradation of high concentration TCPP in UV/H 2 O 2 systems may result in more toxic substances, but its potential application for real wastewater is promising in the future after appropriate optimization, domestication and evaluation. Image 1 • UV/H 2 O 2 system is an effective method to degrade TCPP in aqueous solution. • TCPP was transformed to several hydroxylated and dechlorinated products. • The degradation products of high concentration TCPP were more toxic. [ABSTRACT FROM AUTHOR]

A series of ternary Ag/AgCl/BiVO 4 photocatalysts with different UV light reduction time were synthesized. All the samples were investigated and characterized by XRD, XPS, SEM, PL and so on. The results of UV–Vis DRS and PL demonstrated that the ternary photocatalysts exhibited higher absorption in visible light region. And from the XRD patterns, it could be inferred that with the increase of illumination time, the content of metallic Ag on the surface of ternary photocatalysts increased. In the ternary photocatalyst system, Ag nanoparticles acted as the electron mediator and induced the surface plasmon resonance to facilite the photocatalytic activity of as-obtained ternary photocatalysts. During the photocatalytic degradation of oxytetracycline hydrochloride, the 1 h-Ag/AgCl/BiVO 4 photocatalyst showed the best degradation activity, and the main active species participating in the reaction were holes and superoxide radicals. According to the experimental results, the 1 h-Ag/AgCl/BiVO 4 photocatalyst exhibited excellent stability and effectively degraded OTC under a wide pH range condition or co-existing ions. The experimental results provided a scientific basis for the practical application of the 1 h-Ag/AgCl/BiVO 4 photocatalyst, especially for the treatment of antibiotics in the water. Image 1 • The flower-like sphere Ag/AgCl/BiVO 4 plasmonic photocatalyst was successfully synthesized. • Ag/AgCl/BiVO 4 with one hour ultraviolet irradiation displayed superior photocatalytic activity. • Influence factor study revealed that pH, Cu2+ and NO 3 - are favourable to photocatalytic degradation of OTC by Ag/AgCl/BiVO 4. [ABSTRACT FROM AUTHOR]

The development of novel nano-single-atom-site catalysts with optimized electron configurations and active water adsorption ( * H 2 O) to release hydrogen protons ( * H) is paramount for photocatalytic hydrogen evolution (PHE), a multi-step reaction process involving two electrons. In this study, an atom-confinement and thermal reduction strategy is introduced to achieve synergistic Ag single-atoms (Ag 1 ) and nanoparticles (Ag NPs ) confined within carbon nitride nanotubes (Ag 1+NPs -CN) for enhanced photocatalytic hydrogen evolution. Mechanistic investigations reveal that H 2 O adsorption/dissociation predominantly occurs at Ag 1 sites, while Ag NPs sites notably facilitate H 2 release, indicating the synergistic effect between Ag 1 and Ag NPs in the H 2 evolution reaction. Furthermore, the effective confining of Ag species is beneficial for trapping electrons in highly active reaction regions, while the "electronic metal-support interactions" (EMSIs) of Ag NPs and Ag 1 -C 2 N sites regulate the d-band centers and effectively optimize the adsorption/desorption of intermediates in photocatalytic hydrogen evolution, leading to enhanced H 2 production performance. This work demonstrates the potential of the construction of synergistic photocatalysts for efficient energy conversion and storage; Hydrogen production; Nanoparticles; Photocatalysis; Single atom; and Synergistic effect., (© 2024 Wiley‐VCH GmbH.)

Recently, peracetic acid (PAA) based Fenton (-like) processes have received much attention in water treatment. However, these processes are limited by the sluggish Fe(III)/Fe(II) redox circulation efficiency. In this study, L-cysteine (L-Cys), an environmentally friendly electron donor, was applied to enhance the Fe 3 O 4 /PAA process for the sulfamethoxazole (SMX) abatement. Surprisingly, the L-Cys incorporation was found not only to enhance the SMX degradation rate constant by 3.2 times but also to switch the Fe(IV) dominated nonradical pathway into the • OH dominated radical pathway. Experiment and theoretical calculation result elucidated -NH 2 , -SH, and -COOH of L-Cys can increase Fe solubilization by binding to the Fe sites of Fe 3 O 4 , while -SH of L-Cys can promote the reduction of bounded/dissolved Fe(III). Similar SMX conversion pathways driven by the Fe 3 O 4 /PAA process with or without L-Cys were revealed. Excessive L-Cys or PAA, high pH and the coexisting HCO 3 - /H 2 PO 4 - exhibit inhibitory effects on SMX degradation, while Cl - and humic acid barely affect the SMX removal. This work advances the knowledge of the enhanced mechanism insights of L-Cys toward heterogeneous Fenton (-like) processes and provides experimental data for the efficient treatment of sulfonamide antibiotics in the water treatment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Transition metals are excellent active sites to activate peroxymonosulfate (PMS) for water treatment, but the favorable electronic structures governing  reaction mechanism still remain elusive. Herein, the authors construct typical d-orbital configurations on iron octahedral (Fe Oh ) and tetrahedral (Fe Td ) sites in spinel ZnFe 2 O 4 and FeAl 2 O 4 , respectively. ZnFe 2 O 4 (136.58 min -1 F -1 cm 2 ) presented higher specific activity than FeAl 2 O 4 (97.47 min -1 F -1 cm 2 ) for tetracycline removal by PMS activation. Considering orbital features of charge amount, spin state, and orbital arrangement by magnetic spectroscopic analysis, ZnFe 2 O 4 has a larger bond order to decompose PMS. Using this descriptor, high-spin Fe Oh is assumed to activate PMS mainly to produce nonradical reactive oxygen species (ROS) while high-spin Fe Td prefers to induce radical species. This hypothesis is confirmed by the selective predominant ROS of 1 O 2 on ZnFe 2 O 4 and O 2 •- on FeAl 2 O 4 via quenching experiments. Electrochemical determinations reveal that Fe Oh has superior capability than Fe Td for feasible valence transformation of iron cations and fast interfacial electron transfer. DFT calculations further suggest octahedral d-orbital configuration of ZnFe 2 O 4 is beneficial to enhancing Fe-O covalence for electron exchange. This work attempts to understand the d-orbital configuration-dependent PMS activation to design efficient catalysts., (© 2023 Wiley-VCH GmbH.)

Photocatalytic reduction of CO 2 to value-added solar fuels is of great significance to alleviate the severe environmental and energy crisis. Herein, we report the construction of a synergistic silver nanoparticle catalyst with adjacent atomic cobalt-silver dual-metal sites on P-doped carbon nitride (Co 1 Ag (1+ n ) -PCN) for photocatalytic CO 2 reduction. The optimized photocatalyst achieves a high CO formation rate of 46.82 μmol g cat -1 with 70.1% selectivity in solid-liquid mode without sacrificial agents, which is 2.68 and 2.18-fold compared to that of exclusive silver single-atom (Ag 1 -CN) and cobalt-silver dual-metal site (Co 1 Ag 1 -PCN) photocatalysts, respectively. The closely integrated in situ experiments and density functional theory calculations unravel that the electronic metal-support interactions (EMSIs) of Ag nanoparticles with adjacent Ag-N 2 C 2 and Co-N 6 -P single-atom sites promote the adsorption of CO 2 * and COOH* intermediates to form CO and CH 4 , as well as boost the enrichment and transfer of photoexcited electrons. Moreover, the atomically dispersed dual-metal Co-Ag SA sites serve as the fast-electron-transfer channel while Ag nanoparticles act as the electron acceptor to enrich and separate more photogenerated electrons. This work provides a general platform to delicately design high-performance synergistic catalysts for highly efficient solar energy conversion.

The continuous discharge of antibiotics into the environment poses a serious threat to the ecological environment and human health. In this study, photocatalysis and microalgae were combined to study the removal of tetracycline hydrochloride (TCH) and its photodegradation intermediates in water. The results showed that after photocatalytic treatment, the removal rate of TCH reached 80%, but the mineralization rate was only 17.7%. While Chlorella sp. alone had poor tolerance to high concentrations of TCH, the combined treatment of photocatalysis and microalgae completely removed TCH and increased the mineralization efficiency to 35.0%. Increased cell density was observed, indicating that TCH and the intermediates produced in the photocatalysis process could be utilized by algae for growth. Meanwhile, TCH degradation pathways were proposed based on Liquid Chromatograph Mass Spectrometer analysis, and the toxicity of intermediates detected was predicted using ECOSAR software, which showed that the type and quantity of highly toxic intermediates decreased significantly after subsequent algal treatment. The results demonstrate that photocatalysis and microalgae combined treatment is an efficient and eco-friendly method for the removal of antibiotics in water., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

As persistent and ubiquitous contaminants in water, iodinated X-ray contrast media (ICM) pose a non-negligible risk to the environment and human health. In this study, we investigated the adsorption behavior of two typical ICM compounds, iohexol (IOH) and amidotrizoic acid (DTZ), on magnetic activated carbon. Theoretical investigations, using density functional theory, identified the molecule structures and calculated the molecular diameters of IOH (1.68 nm) and DTZ (1.16 nm), which revealed that ICM could be adsorbed by mesopores and larger micropores. Therefore, magnetic activated carbon with a porous structure was prepared by the co-precipitation method to investigate the adsorption mechanism of IOH and DTZ. MAC--5 (magnetic activated carbon with a theoretical iron oxide content of 37%) showed the best adsorption ability for both IOH and DTZ, with maximum adsorption capacities of 86.05 and 43.00 mg g -1 , respectively. Adsorption kinetics and isotherm models were applied to explore the mechanisms involved, and the effects of solution pH, initial concentration, temperature, ionic strength, and natural organic matter were also investigated. The pore filling effect, π-π stacking, hydrogen bonding, and electrostatic interaction, were found to be the main adsorption mechanisms. The co-adsorption data showed that competition may occur in ICM coexisting environments. Interestingly, the used MAC--5 could be successfully regenerated and its adsorption efficiency did not decrease significantly after five cycles, indicating that it is a promising adsorbent for ICM. The results from this study provide some new insights for the treatment of water containing ICM., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Heavy metal pollution in agricultural soils poses a direct threat to food safety and human health. It has been shown that the colloids is the carrier of heavy metal transport in the polluted soil by heavy metals, but the sources of heavy metals in the soil and colloids and their interrelations are not transparent at present. This study aims to investigate the distribution characteristics of heavy metals in agricultural soils near mining areas, and reveal the relevance of heavy metal content in colloids with total content in soils and their chemical species in soils. Results showed that the concentrations of Mn, Zn, and Pb in agricultural soils and colloids were higher than those of other heavy metals. The content of heavy metals in colloids was positively correlated with the total content of heavy metals in soil. Heavy metals in soil could be easily combined by humus-like substances and tryptophan-like protein in the colloids. The primary source of heavy metals in soil and colloids was mining activities. This study provides theoretical support for revealing the pollution characteristics and migration of heavy metals in agricultural soils and colloids around mining areas., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

This paper demonstrates the successful synthesis of TiO 2 with (001) crystal plane; its morphology and structure were characterized using XRD, TEM and Raman spectrometer. The results showed that TiO 2 nanosheets were bounded by (001) facets on both the top and bottom. TiO 2 -001/UV photocatalytic process was proved to be a powerful method for degrading tri(chloro-propyl) phosphate (TCPP) in aqueous solution. Under the given parameters, 95% of TCPP was removed in 360 min. The photodegradation followed the pseudo-first-order kinetic reaction. The reactive species during photocatalytic oxidation of TiO 2 -001 was mainly hydroxyl radical. TCPP was decomposed into small molecule organics by hydroxyl radicals, along with the release of PO 4 3 - and Cl - , and most of these intermediates were eventually degraded into carbon dioxide and water.

A novel n-n type inorganic/organic heterojunction of flaky-like BiOCl/PDI photocatalyst was constructed by water bath heating method. Meanwhile, a simple method - secondary self-assembly was used to prepare the BiOCl/PDI with a special band structure. The photocatalytic activities were evaluated by degrading aqueous organic pollutants under visible light (λ > 420 nm). The removal rates of 5 mg L -1 phenol (non-ionic type), methyl orange (MO, anionic type), rhodamine B (RhB, cationic type) and 10 mg L -1 RhB by secondary self-assembly BiOCl/PDI (BiOCl/PDI-2) were 8.0%, 3.4%, 27.8% and 78.9% higher than self-assembly BiOCl/PDI (BiOCl/PDI-1) under visible light (λ > 420 nm). The better photocatalytic activity for BiOCl/PDI-2 was attributed to the optimization of energy-band structures, which arose from different exposed surfaces, narrower interplanar spacing and stronger visible light absorption performance. Under acidic condition, BiOCl/PDI-2 showed a good photocatalytic activity, which was not affected by neutral ionic intensity and had good recycling properties. Moreover, the photocatalytic mechanism was explored by free radical capture test and electron paramagnetic resonance (EPR), and contribution of active species was calculated. The main active species of BiOCl/PDI-2 were ·O 2 - , 1 O 2 and h + . Our work may provide a route to design efficient inorganic/organic heterojunctions for organic pollutants degradation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Peanut shell biochar (BC) supported on Cu-doped FeOOH composite (Cu-FeOOH/BC) was synthesized using a facile and scalable method. The Cu-FeOOH/BC samples were characterized by Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), scanning electron microscopy equipped with an energy-dispersive spectrometer (SEM-EDS), x-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) techniques. Novel catalytic composites with different Cu/Fe molar ratios were compared systematically by activating persulfate (PS) for the tetracycline (TC) degradation. 0.5Cu-1FeOOH/BC (Cu/Fe molar ratio = 0.5:1) was confirmed as the optimum activation material and the removal of TC reached 98.0% after 120 min by combining with 20 mM PS at pH 7.0 and 25 °C. The influencing factors including catalyst loading, PS dosage, water matrix species, and pH on the performance system of 0.5Cu-1FeOOH/BC-PS were investigated, respectively. Reaction rate constants (K obs ) on catalyst dosages (0.05, 0.10, 0.20, and 0.30 g L -1 ) were 0.0072, 0.0101, 0.0244, and 0.0144 min -1 , and 0.0090, 0.0146, 0.0244, and 0.0178 min -1 for the change of PS concentrations (5, 10, 20, and 30 mM), which indicated that increasing the concentrations of catalyst and PS appropriately improved TC degradation, but excessive dosages inhibited the reaction process of TC removal. The TC removal rate was inhibited by inorganic anions with the following order of HCO 3 - > Cl - > HPO 4 2- > SO 4 2- > NO 3 - . Free radical quenching and capture experiments under different pH values revealed that sulfate radicals existed predominantly in acidic conditions and hydroxyl radicals in alkaline conditions. The catalyst showed an excellent recyclability and stability and the removal efficiency of TC still remained over 90% after five consecutive uses. To conclude, coupling of 0.5Cu-1FeOOH/BC and PS can be successfully applied as an effective and stable technique for the treatment of refractory organic pollutants in wastewater.

Microwave-assisted photocatalytic (MAPC) degradation of atrazine over nanotitania coated multiwalled carbon nanotubes (TiO(2)/MWCNTs) was investigated in this study. As a result, degradation efficiency of atrazine over TiO(2)/CNTs prepared by hydrothermal method was about 30% and 20% higher than that of titania P25 and anatase prepared hydrothermally in given time. The TiO(2)/CNTs composite samples were characterized by TGA-DSC, TEM, UV-vis DRS, XRD and BET, to explain the reason for efficient degradation and adsorption process of atrazine. Microwave thermal effect in this process was also investigated. Intermediates of degradation both in MAPC process and microwave-assisted photodegradation (MAPD) process were identified by LC/MS. It suggests that MWCNTs have special effects on atrazine degradation during MAPC process, like strong microwave absorption capability.

Aqueous crystal violet (CV) solutions containing P25-TiO(2) photocatalyst were irradiated with ultraviolet-visible (UV-vis) light from two microwave-powered electrodeless discharge lamps (EDL(-2)). The results demonstrated that approximately 94.4% of CV was effectively removed after 3 min of irradiation, with a pseudo-first order kinetic constant of 0.838 min(-1). According to 32 kinds of products, a five-step degradation pathway of CV was proposed. Further investigations showed that (1) three kinds of N-demethylated products and 4-dimethylaminobenzophenone (DLBP) were the main intermediates; (2) malachite green (MG) and leuco-crystal violet could not be generated by N-demethylation and phototransformation reactions, respectively; (3) bis(4-(dimethylamino)phenyl)methanone preferentially generated via decomposition of the conjugated structure of CV could be further N-demethylated into DLBP. Moreover, the unique degradation pathways of CV and MG were ascribed to the different substituents on the conjugated structures. Additionally, the cost and kinetic constant of different processes was also evaluated, and the results indicated the feasibility of this method for treatment of CV in field situations., (Copyright © 2010 Elsevier B.V. All rights reserved.)

With the popular methods of CoMFA and CoMSIA, three-dimensional quantitative structure-activity relationships (QSARs) were newly developed for the toxicity of polybrominated diphenyl ethers (PBDEs). The choice of optimized geometries by density functional theory (DFT) as molecular template and the RMSD-based molecular alignment strategy might mostly contribute to the QSAR improvement, which was highlighted specifically by the increased q2 of 0.870 for CoMFA, 0.887 for CoMSIA, respectively. QSARs analyzes indicated that the steric effects from ortho- and meta-substitution and the correlated hydrophobicities have the greatest impact on the binding affinities of aryl hydrocarbon receptor (AhR) to PBDEs. Though the effects of electrostatics were comparatively inferior in the AhR binding, the aromatic interaction and possible charge transfer proved to be indispensable for toxicity mediation. Consistent with that proposed previously for other structurally similar compounds, such as dioxins and polychlorinated biphenyls, the predictive toxicology was helpful to understand the congener-specificity of toxicity of PBDEs., (Copyright (c) 2009 Elsevier Inc. All rights reserved.)

The effect of two solubilizers, Tween80 and beta-cyclodextrin (BCD) on the distribution of herbicide mefenacet (MF) in soil-water system was investigated. The results indicated that in the absence of Tween80 and BCD, the adsorption of MF on the natural soils fitted well with the Freundlich model and the K(f) values were positively related to organic carbon content in the soils. The K(oc) values were in the ranges of 52.7-606.6 L kg(-1). Desorption of MF from the soils was irreversible and positive hysteresis was observed in all the cases. In addition, it was found that the solubility of MF in aqueous phase could be enhanced greatly in the presence of Tween80 and BCD. The adsorption isotherms of Tween80 were fitted well with the linear Langmuir sorption model, and that of BCD fitted well with linear adsorption model. Moreover, it was also observed that the presence of proper concentration of Tween80 and BCD can enhance the transfer of MF from soil phase to aqueous phase. Although BCD presented more adsorption loss than Tween80, a carbon-normalized model suggested the adsorbed BCD had a weaker affinity for MF than the adsorbed Tween80, and experiment results showed the BCD could be a more effective solvent for desorption of MF compared with Tween80. The present study indicated that Tween80 and BCD had great potential in the area of ex situ enhanced soil remediation especially that based on full dynamic mixed model., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)

A microwave assisted zero-valent iron oxidation process was studied in order to investigate the synergetic effects of MW irradiation on Fe/EDTA system (Fe/EDTA/MW) treated 4-nitrophenol (4-NP) from aqueous solution. The results indicated that the thermal effect of microwave improved the removal effect of 4-NP and TOC through raising the temperature of the system, as well as the non-thermal effect generated by the interaction between the microwave and the Fe resulting in an increase in the hydrophobic character of Fe surface. During the degradation of 4-NP in Fe/EDTA/MW system, the optimum value for MW power, Fe, EDTA dosage was 400 W, 2 g and 0.4 mM, respectively. The possible pathway for degrading the 4-NP was proposed based on GC/MS and HPLC analysis of the degradation intermediates. The concentration change course of the main bio-refractory by-products, the aminophenol formed in the degradation of 4-NP suggested a more efficient degradation and mineralization in Fe/EDTA/MW system. Finally, BOD(5)/COD(Cr) of the solution increased from 0.237 to 0.635 after reaction for 18 min, indicating that the biodegradability of wastewater was greatly improved by Fe/EDTA/MW system and would benefit to further treatment by biochemical methods., (Crown Copyright 2009. Published by Elsevier B.V. All rights reserved.)

The present study described the degradation behavior of tetrabromobisphenol A (TBBPA) in Fe-Ag suspension solutions under ultrasonic radiation (US). The Fe-Ag bimetallic nanoparticles with core-shell structure were successfully synthesized by reduction and deposition of Ag on nanoscale Fe surface, and were further characterized by BET, XRD, TEM, SEM, X-ray fluorescence and X-ray photo-electron spectroscopy. The results revealed that the displacement plating produced a non-uniform overlayer of Ag additive on iron; the as-synthesized bimetallic nanoparticles were spherical with diameters of 20-100 nm aggregated in the form of chains. Batch studies demonstrated that the TBBPA (2 mg L(-1)) was completely degraded in 20 min over Fe-Ag nanoparticles, which has higher degradation efficiency than Fe(0) nanoparticles under US. The effects of Fe-Ag bimetallic nanoparticles loading, initial TBBPA concentration, pH of the solution, Ag loading and temperature on the reduction efficiency of TBBPA under US were investigated. The complete reduction of TBBPA in 20 min was determined selectively under the conditions of pH (pH=6.0+/-0.5), Ag loading(1 wt.%) at 30 degrees C over the fabricated Fe-Ag nanoparticles. Additionally, the major intermediates identified by LC-MS technique were tri-BBPA, di-BBPA, mono-BBPA and BPA and the degradation mechanism was also proposed., (2010. Published by Elsevier Ltd. All rights reserved.)

F-Si-co-modified TiO(2) (FST) samples with different ratios of fluorine to titanium (R(F)) and silica to titanium (R(x)), were successfully synthesized by ultrasound-assisted hydrolysis. The structure and properties of the as-prepared codoped titania were characterized by means of XRD, TEM, XPS, BET, UV-Vis diffuse reflectance spectra and ESR. XRD analysis showed that Si and F atoms prevented phase transition of anatase to rutile and suppressed the growth of titania crystalline. ESR results showed that the concentration of the active species (.OH) on 1%-FST(R(x)=10%) was higher than that on other FST samples and P25 titania. The improvement in photocatalytic activity relative to titania can be achieved by co-modifying fluorine and silica to fabricate FST composite material. The photocatalytic activity of FST powders for decomposition of methyl orange was affected by the content of fluorine and the content of silica. When the ratios of R(F) and R(x) were 1 and 10%, respectively, 1%-FST(R(x)=10%) shows the best among photocatalytic activity, which is much superior to P25 under UV-Vis irradiation. The possible reasons for the high photocatalytic activity of the FST powders were proposed in the paper. In addition, the stability of the FST powders in photocatalytic process was confirmed based on the XPS analysis., ((c) 2009 Elsevier B.V. All rights reserved.)

Nickel oxide catalyst was obtained by precipitation-oxidation method with the assistance of microwave irradiation. The samples were characterized by X-ray diffraction, Raman spectrophotometer, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, surface area and porosity analyzer. On the basis of the results, the as-prepared product was nano-NiO(2) with OH group and active oxygen. The catalytic activity of the as-prepared product might be attributed to its microwave absorbing property and the role of active oxygen, OH group under microwave irradiation. The microwave induced catalytic degradation process (MICD) with as-prepared product was further applied to degrade triphenylmethane dye crystal violet (CV). 97% of a 100 mg L(-1) sample of CV was rapidly degraded in 5 min with the corresponding 81% TOC removal. The main intermediates were separated and identified by LC-ESI-MS and GC-MS techniques. The LC-ESI-MS analytical results demonstrated that a series of N-de-methylation products were obtained in a stepwise manner, namely mono-, di-, tri-, tetra-, penta-, and hexa-de-methylated CV species. Nine organic acids with benzene ring and four low molecular acids were yielded with the assistance of GC-MS. The proposed degradation pathways were discussed in this study. The degradation processes might include N-de-methylation, destruction of conjugated structure and opening-benzene ring. MICD, as a potential technique with wide application perspective, can be used to purify triphenylmethane dye wastewater with nanosized nickel dioxide.

The ultraviolet (UV) photolysis of atrazine in aqueous solution was investigated at wavelength of 254 nm in this study. This paper was mainly focused on the identification of atrazine degradation intermediates by HPLC-MS/MS and its degradation mechanisms. The photodegradation products included the following seven classes: dechloro-hydroxylated products, chloro-dealkylated products, dechloro-dealkylated products, alkylic-oxidated products, delamination-hydroxylated products, olefinic products, and dechloro-hydrogenated products which were never reported in direct photolytic process, 4-isopropylamino-6-ethylamino-s-triazine (IEST), 4,6-dihydroxy-s-triazine (OOST). The main degradation products were 2-hydroxy-4-acetamido-6-ethylamino-s-triazine (OIET), 2-chloro-4-isopropyl-amino-6-methylamino-s-triazine (CIMT), 2-chloro-4,6-divinylamino-s-triazine (CVVT), 2-chloro-4-ethylamino-6-amino-s-triazine(CEAT), 2-methoxy-4-isopropyl-amino-6-methylamino-s-triazine (OIMT), 2-hydroxy-4-acetamindo-6-ethylamino-s-triazine (ODET), etc. Finally, the possible degradation mechanism was also proposed here.

This work was originally performed to compare H(2)O(2)-based degradation of aqueous malachite green (MG) under microwave (MW)-enhanced and conventional heating (CH)-enhanced conditions, with the whole reaction courses traced by UV-vis spectrophotometer. The results showed that the higher discoloration rates of MG were available during MW-enhanced process, implying that the special heating way of MW might be more benefit for the generation of hydroxyl radicals than that of CH. Furthermore, major intermediates were separated and identified by HPLC-ESI-MS and GC-MS techniques. On the basis of 53 intermediates, degradation mechanism was deduced as follows: firstly, N-de-methylation reactions. Secondly, adduction reactions. Thirdly, decomposition of conjugated structure reactions of MG. Fourthly, removal of benzene reactions. Finally, open-ring reactions. Additionally, results revealed that microwave-enhanced H(2)O(2)-based treatment had more advantages, such as higher degradation efficiency, and no removal of catalyst after treatment.

The present study investigated the feasibility of using two mixed surfactants, anionic surfactant sodium dodecylbenzenesulfonate (SDBS) and nonionic surfactant polysorbate 80 (Tween80), for the remediation of p-nitrochlorobenzene (pNCB) contaminated soil. The water solubility, the apparent soil-water distribution constant (K(d)(*)) and the desorption ratio of pNCB, as well as the sorption of surfactants by the soil were significantly affected by the dosage of surfactants and the mass ratio of SDBS/Tween80. Because of the formation of mixed micelles, the presence of SDBS showed more effective than individual Tween80 for increasing the water solubility, decreasing the K(d)(*) and enhancing the desorption ratio of pNCB, as well as inhibiting the sorption of surfactants by the soil. Low dosage of surfactants (Tween80 < 2000 mg L(-1)) increased the K(d)(*) value and inhibited the desorption of pNCB from soil. However, relative high concentration of Tween80 had positive effect on the decrease of the K(d)(*) value and increase of pNCB desorption. In addition, among the tested surfactant systems, mixed SDBS/Tween80 with a 1:1 mass ratio exhibited the highest pNCB desorption. The results indicated that it is feasible to use mixed SDBS/Tween80 surfactants for the remediation of pNCB contaminated soil.

The chemical oxidation of the herbicide ametryn was investigated by aqueous chlorination between pH 4 and 10 at a temperature of 25 degrees C. Ametryn was found to react very rapidly with aqueous chlorine. The reaction kinetics can be well described by a second-order kinetic model. The apparent second-order rate constants are greater than 5 x 10(2)M(-1)s(-1) under acidic and neutral conditions. The reaction proceeds much more slowly under alkaline conditions. The predominant reactions were found to be the reactions of HOCl with neutral ametryn and the charged ametryn, with rate constants equal to 7.22 x 10(2) and 1.58 x 10(3)M(-1)s(-1), respectively. The ametryn degradation rate increases with addition of bromide and decreases with addition of ammonia during the chlorination process. Based on elementary chemical reactions, a kinetic model of ametryn degradation by chlorination in the presence of bromide or ammonia ion was also developed. By employing this model, we estimate that the rate constants for the reactions of HOBr with neutral ametryn and charged ametryn were 9.07 x 10(3) and 3.54 x 10(6)M(-1)s(-1), respectively. These values are 10- to 10(3)-fold higher than those of HOCl, suggesting that the presence of bromine species during chlorination could significantly accelerate ametryn degradation.

The photocatalytic degradation of rhodamine B (RhB) over NaBiO3 under visible light irradiation was investigated in this study. RhB (20 mg/L) was almost completely decolorized in 30 min in given conditions. It was found that catalyst heating temperature significantly influenced the photocatalytic activity of the catalyst in which crystal water may played an important role, and the original sample exhibited higher activity than the heated samples did. To scrutinize the mechanistic details of the dye photodegradation, several critical analytical methods including UV-vis spectroscopy, HPLC, LC/MS/MS, and GC/MS were utilized to monitor the temporal course of the reaction. All N-deethylation intermediates and several small molecular products were separated and identified. The yield distinctness between two isomer intermediates (DR and EER) was considered to be correlated with the changes in the electron density of the dye molecule. Then two possible competitive photodegradation pathways of RhB over NaBiO3 were proposed: Chromophore cleavage and N-deethylation. Yet, cleavage of dye chromophore structure predominated over the N-deethylation.

A "two-stage biological aerated filter" (T-SBAF) consisting of two columns in series was developed to treat electroplating-wastewater. Due to the low BOD/CODcr values of electroplating-wastewater, "twice start-up" was employed to reduce the time for adaptation of microorganisms, a process that takes up of 20 days. Under steady-state conditions, the removal of CODcr and NH(4)(+)-N increased first and then decreased while the hydraulic loadings increased from 0.75 to 1.5 m(3) m(-2) h(-1). The air/water ratio had the same influence on the removal of CODcr and NH(4)(+)-N when increasing from 3:1 to 6:1. When the hydraulic loadings and air/water ratio were 1.20 m(3) m(-2) h(-1) and 4:1, the optimal removal of CODcr, NH(4)(+)-N and total-nitrogen (T-N) were 90.13%, 92.51% and 55.46%, respectively. The effluent steadily reached the wastewater reuse standard. Compared to the traditional BAF, the period before backwashing of the T-SBAF could be extended to 10days, and the recovery time was considerably shortened.

Novel polyaniline (PANI) electrodeposited in the presence of fluorinated organic acid was applied as a new conductive polymer-based solid-phase microextraction (SPME) fiber candidate. Polychlorinated biphenyls (PCBs) were selected as representative compounds. Improved temperature resistance (<500 degrees C) and satisfactory extraction efficiency were obtained by introduction of fluorinated organic acid. Extraction efficiency of novel PANI for PCBs was superior to common PANI (synthesized in sulfuric acid) and polythiophene, and comparable to commercial 30 microm PDMS but with thinner stationary, i.e. 10 microm. Quantitative determination of trace PCBs in water samples was carried out using this novel SPME fiber, coupling with selective gas chromatography-microelectron capture detector (GC-microECD). The proposed method provided a linear range of approximately three orders. The detection limits were 0.05 ng L(-1) for PCB 138, 153 and 180, and 0.1 ng L(-1) for PCB 28, 52 and 101, respectively. The method was successfully applied to the analysis of spiked surface water samples with the recoveries from 83.0 to 110.7%.

Bi(2)WO(6) was successfully synthesized by a facile hydrothermal method, and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and BET. As a result, Bi(2)WO(6) crystals displayed mainly square-plate-like morphologies with a short edge and the average crystalline size was in the range of 50-150 nm. Then microwave-assisted photocatalytic degradation of rhodamine B (RhB) using Bi(2)WO(6) was investigated. The results illustrated that RhB (10 mg/L) was bleached effectively and the removal efficiency was about 94% in 60 min. Effect of electron accepting agent (air, H(2)O(2)) on the degradation efficiency of RhB was also examined. Degradation intermediates of RhB in the presence of H(2)O(2) were identified by LC/MS/MS and GC/MS. All five N-de-ethylated intermediates were monitored by LC/MS/MS easily, and seven organic acids such as succinic acid, benzoic acid, adipic acid, 3-hydroxybenzoic acid, phthalic acid, etc., were also detected by GC/MS. The possible degradation mechanism of RhB in the presence of H(2)O(2) included four processes: N-de-ethylation, chromophore cleavage, opening-ring and mineralization, which coexisted in microwave-assisted photocatalytic system.

A novel photocatalysis material, F-Si-comodified TiO(2) (FST) powder, was synthesized by ultrasound-assisted hydrolysis. The prepared material was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV-visible absorption spectroscopy, respectively. XRD analysis indicated that the phase of FST was pure anatase and Si atoms suppressed the growth of titania crystalline, XPS spectra showed that FST was composed of Ti, O, Si and F element, the band gap energy of FST calculated according to the spectrum of UV-vis absorption was 3.26 eV. The electron spin resonance (ESR) spin-trapping technique using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as the spin-trap reagent has been applied to detect free radical intermediates generated from FST. ESR results showed the concentration of the active species (OH) on FST is higher than those on F-doping TiO(2) (FT), Si-modifying TiO(2) (ST) and P25 titania. The degradation of pentachlorophenol (PCP) in the microwave-assisted photocatalysis (MAPC) process was faster than other processes including microwave-assisted direct photolysis (MADP), microwave process alone (MP) and dark process (DP). The photocatalytic activity of FST is much higher than that of ST, FT and P25 titania. It may be attributed to its strong capacity of absorption to the UV-vis irradiation and more hydroxyl radical on surface of FST. In MPAC process, 40 mg L(-1) PCP was completely degraded in 20 min and its corresponding mineralization efficiency was 71%, the pH of solutions decreased from 10.3 to 6.47 and the dechlorination was completed in 12 min. The intermediates products of PCP in MAPC process identified by GC/MS were trichlorophenols (TCP), tetrachlorophenols (TTCP) and tetrachlorocatechol (TTCC) and the possible mechanism of PCP degradation is proposed.

The photocatalytic degradation of Rhodamine B (RhB) was carried out using TiO2 supported on activated carbon (TiO2-AC) under microwave irradiation. Composite catalyst TiO2-AC was prepared and characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET). In the process of microwave-enhanced photocatalysis (MPC), RhB (30 mg/L) was almost completely decoloured in 10 min, and the mineralization efficiency was 96.0% in 20 min. The reaction rate constant of RhB in MPC using TiO2-AC by pseudo first-order reaction kinetics was 4.16 times of that using Degussa P25. Additionally, according to gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry (LC/MS) identification, the major intermediates of RhB in MPC included two kinds of N-de-ethylation intermediates (N,N-diethyl-N'-ethyl-rhodamine (DER)), oxalic acid, malonic acid, succinic acid, and phthalic acid, maleic acid, 3-nitrobenzoic acid, and so on. The degradation of RhB in MPC was mainly attributed to the destruction of the conjugated structure, and then the intermediates transformed to acid molecules which were mineralized to water and carbon dioxide.

Microwave-assisted photocatalytic (MPC) degradation of malachite green (MG) in aqueous TiO2 suspensions was investigated. A 20 mg/L sample of MG was rapidly and completely decomposed in 3 min with the corresponding TOC removal efficiency of about 85%. To gain insight into the degradation mechanism, both GC-MS and LC-ESI-MS/MS techniques were employed to identify the major intermediates of MG degradation, including N-demethylation intermediates [(p-dimethylaminophenyl)(p-methylaminophenyl)phenylmethylium (DM-PM), (p-methylaminophenyl)(p-methylaminophenyl)phenylmethylium (MM-PM), (p-methylaminophenyl)(p-aminophenyl)phenylmethylium (M-PM)]; a decomposition compound of the conjugated structure (4-dimethylaminobenzophenone (DLBP)); products resulting from the adduct reaction of hydroxyl radical; products of benzene removal; and other open-ring intermediates such as phenol, terephthalic acid, adipic acid, benzoic acid, etc. The possible degradation mechanism of MG included five processes: the N-demethylation process, adduct products of the hydroxyl radical, the breakdown of chromophores such as destruction of the conjugated structure intermediate, removal of benzene, and an open-ring reaction. To the best of our knowledge, it is the first time the whole MG photodegradation processes have been reported.

TiO2 thin films were deposited on granular activated carbon by a dip-coating method at low temperature (373 K), using microwave radiation to enhance the crystallization of titania nanoparticles. Uniform and continuous anatase titania films were deposited on the surface of activated carbon. BET surface area of TiO2-mounted activated carbon (TiO2/AC) decreased a little in comparison with activated carbon. TiO2/AC possessed strong optical absorption capacity with a band gap absorption edge around 360 nm. The photocatalytic activity did not increase when the as-synthesized TiO2/AC was thermally treated, but was much higher than commercial P-25 in degradation of phenol by irradiation of electrodeless discharge lamps (EDLs).

Taking pentachlorophenol (PCP) as a reference, we investigated the photoelectrocatalytic degradation of organic pollutants using a rutile nanotube-like TiO(2)/Ti film electrode. The nanotube-like TiO2 electrode was prepared by first oxidizing the surface of a titanium sheet to form rutile TiO2 and then treating it to form the tubular structure in NaOH aqueous solution. The occurrence of PCP degradation was indicated by the decrease in pH, concentration of PCP and TOC, and by the formation of chloride ions. The photoelectrochemical (PEC) efficiency of the nanotube-like TiO2/Ti electrode has been determined in terms of degradation of PCP and the incident photo-to-current conversion efficiency (IPCE). The experimental results showed that PCP could be degraded more efficiently by a photoelectrocatalytic process than by a photocatalytic or electrochemical oxidation alone. A significant photoelectrochemical synergetic effect was observed. The kinetic constant of PEC degradation of PCP using a nanotube-like TiO2 electrode was over 60% higher than that using a TiO2 film electrode. It is noted that chloride ion and hydrogen ion concentration increased with irradiation time in the PEC degradation of PCP; PCP was gradually mineralized and the complete minimization of PCP took more time than its degradation.

Titanium oxide nanotubes were successfully grown from a titanium plate by direct anodic oxidation with 0.2 wt % hydrofluoric acid being the supporting electrolyte. These nanotubes are of uniform size and are well-aligned into high-density arrays. They look like honeywell with the structure similar to that of porous alumina obtained by the same technique. TiO2 anatase phase was identified by X-ray diffraction. Significant blue-shift in the spectrum of UV- vis absorption was observed. The mechanism of the novel, simple, and direct growth of the nanotubes was postulated. To investigate their potentials in environmental applications, degradation of pentachlorophenol (PCP) in aqueous solution was carried out using photoelectrocatalytic (PEC) processes, comparing with electrochemical process (EP) and photocatalytic (PC). A significant photoelectrochemical synergetic effect was observed. The kinetic constant of PEC degradation of PCP using TiO2 nanotubes electrode was 86.5% higher than that using TiO2 film electrode. In degrading PCP, 70% of TOC was removed using the TiO2 nanotubes electrode against 50% removed using TiO2 film electrode formed by sol-gel method in 4 h under similar conditions.