Elucidating the photodissociation fingerprint and quantifying the determination of organic hydroperoxides in gas-phase autoxidation.

Hydroperoxides are formed in the atmospheric oxidation of volatile organic compounds, in the combustion autoxidation of fuel, in the cold environment of the interstellar medium, and also in some catalytic reactions. They play crucial roles in the formation and aging of secondary organic aerosols and in fuel autoignition. However, the concentration of organic hydroperoxides is seldom measured, and typical estimates have large uncertainties. In this work, we developed a mild and environmental-friendly method for the synthesis of alkyl hydroperoxides (ROOH) with various structures, and we systematically measured the absolute photoionization cross-sections (PICSs) of the ROOHs using synchrotron vacuum ultraviolet-photoionization mass spectrometry (SVUV-PIMS). A chemical titration method was combined with an SVUV-PIMS measurement to obtain the PICS of 4-hydroperoxy-2-pentanone, a typical molecule for combustion and atmospheric autoxidation ketohydroperoxides (KHPs). We found that organic hydroperoxide cations are largely dissociated by loss of OOH. This fingerprint was used for the identification and accurate quantification of the organic peroxides, and it can therefore be used to improve models for autoxidation chemistry. The synthesis method and photoionization dataset for organic hydroperoxides are useful for studying the chemistry of hydroperoxides and the reaction kinetics of the hydroperoxy radicals and for developing and evaluating kinetic models for the atmospheric autoxidation and combustion autoxidation of the organic compounds.

Experimental and Updated Kinetic Modeling Study of Neopentane Low Temperature Oxidation.

Neopentane is an ideal fuel model to study low-temperature oxidation chemistry. The significant discrepancies between experimental data and simulations using the existing neopentane models indicate that an updated study of neopentane oxidation is needed. In this work, neopentane oxidation experiments are carried out using two jet-stirred reactors (JSRs) at 1 atm, at a residence time of 3 s, and at three different equivalence ratios of 0.5, 0.9, and 1.62. Two different analytical methods (synchrotron vacuum ultraviolet photoionization mass spectrometry and gas chromatography) were used to investigate the species distributions. Numerous oxidation intermediates were detected and quantified, including acetone, 3,3-dimethyloxetane, methacrolein, isobutene, 2-methylpropanal, isobutyric acid, and peroxides, which are valuable for validating the kinetic model describing neopentane oxidation. In the model development, the pressure dependencies of the rate constants for the reaction classes Q̇OOH + O2 and Q̇OOH decompositions are considered. This addition improves the prediction of the low-temperature oxidation reactivity of neopentane. Another focus of model development is to improve the prediction of carboxylic acids formed during the low-temperature oxidation of neopentane. The detection and identification of isobutyric acid indicates the existence of the Korcek mechanism during neopentane oxidation. Regarding the formation of acetic acid, the reaction channels are considered to be initiated from the reactions of ȮH radical addition to acetaldehyde/acetone. This updated kinetic model is validated extensively against the experimental data in this work and various experimental data available in the literature, including ignition delay times (IDTs) from both shock tubes (STs) and rapid compression machines (RCMs) and JSR speciation data at high temperatures.

Study on the performance efficiency, mechanism, power consumption and biochemical properties of E/Ce(IV)/PMS on the enhanced removal of RB19.

In this study, an advanced oxidation process with E/Ce(IV) synergistic PMS (E/Ce(IV)/PMS) was established for the efficient removal of Reactive Blue 19 (RB19). The catalytic oxidation performance of different coupling systems was examined and the synergistic effect of E/Ce(IV) with PMS in the system was substantiated. The oxidative removal of RB19 in E/Ce(IV)/PMS was excellent, achieving a removal efficiency of 94.47% and a reasonable power consumption (EE/O value was 3.27 kWh·m-3). The effect of pH, current density, Ce(IV) concentration, PMS concentration, initial RB19 concentration and water matrix on the removal efficiency of RB19 were explored. Additionally, quenching and EPR experiments showed that the solution contains different radicals such as SO4·-, HO∙ and 1O2, where 1O2 and SO4·- played key roles, but HO∙ just acted a weaker role. Ce ion trapping experiment confirmed that Ce(IV) was involved in the reaction process and played a major role (29.91%). RB19 was subject to three possible degradation pathways, and the intermediate products displayed well biochemical properties. To conclude, the degradation mechanism of RB19 was explored and discussed. In the presence of current, E/Ce(IV)/PMS performed a rapid Ce(IV)/Ce(III) cycle, continuously generating strong catalytic oxidation Ce(IV), The reactive radicals derived from the decomposition of PMS, in conjunction with Ce(IV) and direct electro-oxidation, efficiently destroyed the molecular structure of RB19 and showed an efficient removal rate.

Measurement and summary of photoionization data for biomass-derived compounds.

RATIONALE: Biomass is a potential feedstock for making liquid fuels and valuable chemicals. Quantitative analysis of biomass conversion in real time by photoionization mass spectrometry (PIMS) is an important way to understand the reaction process. However, the lack of photoionization data for biomass-derived compounds limits the research using PIMS. METHODS: Measurements of photoionization data were performed with synchrotron vacuum ultraviolet PIMS. Toluene and methanol were used as calibrated references and solvents in this experiment since their photoionization cross-sections (PICS) are well documented in the literature. RESULTS: The ionization energies (IEs) of 23 biomass-derived compounds were measured. Among them, the PICSs of 14 compounds were calibrated and presented. Besides, the IEs of 95 other biomass-derived compounds and their typical fragment ions were also summarized. CONCLUSIONS: A photoionization database related to IEs and PICSs of biomass-derived compounds (m/z < 200) is established. PICSs of most biomass-derived compounds have low values at the most frequently used photoionization energy of 10.5 eV. Lignin-derived compounds have lower IEs than carbohydrate-derived compounds.

Unusual Diradical Intermediates in Ozonolysis of Alkenes: A Combined Theoretical and Synchrotron Radiation Photoionization Mass Spectrometric Study on Ozonolysis of Alkyl Vinyl Ethers.

Calculations and experiments were conducted on ozonolysis of ethyl vinyl ether (EVE) and butyl vinyl ether to identify an unconventional diradical intermediate generated from the O-O bond cleavage of primary ozonide. The diradical can undergo a H atom shifting process that yields keto-hydroperoxide (KHP), the characteristic product that identifies the existence of a diradical intermediate. RRKM-ME calculation, based on the PES at the CCSD(T)/VTZ//M06-2X/6-311++G(2df,2p) level, disclosed branching ratios of ∼0.65% for KHP formation. Using synchrotron-generated vacuum-ultraviolet photoionization mass spectrometry measurements, the formation of KHPs (C4H8O4) in ozonolysis of EVE was confirmed by ion signals of C4H8O4+ (ionization of KHP) and C4H7O2+ (ion fragment from the loss of HO2 from KHP) by comparing their photoionization efficiency spectra with the calculated adiabatic ionization energies and appearance energies.

Electrically supported mediator Co(II)-activated peroxydisulfate synergistic process for organic contaminants elimination.

Among homogeneous catalysts, cobalt ions exhibit ultra-high persulfate activation performance. In this work, an electrically supported medium Co(II) activated peroxydisulfate synergistic process was established to eliminate organic contaminants in water. The synergistic catalytic effect was verified by comparing the oxidative degradation performance and reaction rate constant of different coupling systems. The decolorization ability of E-Co(II)-PDS on reactive black 5 (RB5) was explored, and the results showed that the removal rate of RB5 can reach 93.21% under the optimized conditions of current density of 5.71 mA/cm2, initial pH of 4, Co(II) concentration of 0.2 mM and PDS concentration of 5 mM. The effect of water matrix on the removal of RB5 was studied, and it was found that HCO3- and humic acid significantly inhibited the degradation of RB5, while Cl- and H2PO4- could effectively promote it at a certain concentration. Notably, the degradation of RB5 in E-Co(II)-PDS system achieved lower energy consumption, with an energy consumption per unit volume (EE/O) value of 0.4304 kWh·m-3. EPR test, quenching experiments and contribution rate analysis showed that the oxidation active species in E-Co(II)-PDS process were Co(III), sulfate radicals and hydroxyl radicals, and their oxidation contribution rates were 15.72%, 12.69% and 53.25%, respectively. Finally, the decomposition process of RB5 was proposed by the mass spectrometry results. The electric current promotes cobalt ion cycling and PDS activation through electron transfer, and induces Co(II) to promote the activation of PDS, which is the main mechanism of E-Co(II)-PDS system to achieve the robust degradation ability of RB5.

Robust operation of distribution network based on photovoltaic/wind energy resources in condition of COVID-19 pandemic considering deterministic and probabilistic approaches.

In this paper, optimal allocation and planning of wind and photovoltaic energy resources are performed in a distribution network with the objective of reducing losses, improving reliability, and minimizing energy generation cost in terms of changes in load consumption pattern during the COVID-19 pandemic condition. The main goal is identifying the best operating point, ie the optimal location and size of clean energy resources in the worst load change conditions, which ensures the best network operation in all conditions during the COVID-19 condition via the turbulent flow of water-based optimization (TFWO). First, the deterministic approach is implemented in Hybrid and Distributed cases before and during COVID-19 conditions. The probabilistic approach is performed considering generation uncertainty during the COVID-19 conditions. The results showed better performance in the Distributed case with the lowest losses and higher reliability improvement. Moreover, the losses are significantly reduced and the reliability is improved during the COVID-19 pandemic conditions. The findings indicate that the allocation and planning during the COVID-19 conditions is a robust option in network operating point changes. Also, the probabilistic results showed that considering the uncertainty has increased active and reactive losses (4.67% and 5.82%) and weakened the reliability (10.26%) of the deterministic approach.

Graphene-Nanorod Enhanced Quasi-Van Der Waals Epitaxy for High Indium Composition Nitride Films.

The nitride films with high indium (In) composition play a crucial role in the fabrication of In-rich InGaN-based optoelectronic devices. However, a major limitation is In incorporation requiring a low temperature during growth at the expense of nitride dissociation. Here, to overcome this limitation, a strain-modulated growth method, namely the graphene (Gr)-nanorod (NR) enhanced quasi-van der Waals epitaxy, is proposed to increase the In composition in InGaN alloy. The lattice transparency of Gr enables constraint of in-plane orientation of nitride film and epitaxial relationships at the heterointerface. The Gr interlayer together with NRs buffer layer substantially reduces the stress of the GaN film by 74.4%, from 0.9 to 0.23 GPa, and thus increases the In incorporation by 30.7%. The first principles calculations confirm that the release of strain accounts for the dramatic improvement. The photoluminescence peak of multiple quantum wells shifts from 461 to 497 nm and the functionally small-sized cyan light-emitting diodes of 7 × 9 mil2 are demonstrated. These findings provide an efficient approach for the growth of In-rich InGaN film and extend the applications of nitrides in advanced optoelectronic, photovoltaic, and thermoelectric devices.

H2 O-Etchant-Promoted Synthesis of High-Quality Graphene on Glass and Its Application in See-Through Thermochromic Displays.

Direct growth of graphene on glass can bring an innovative revolution by coupling the complementary properties of traditional glass and modern graphene (such as transparency and conductivity), offering brand new daily-life related applications. However, preparation of high-quality graphene on nonmetallic glass is still challenging. Herein, the direct route of low sheet resistance graphene on glass is reported by using in situ-introduced water as a mild etchant and methane as a carbon precursor via chemical vapor deposition. The derived graphene features with large domain sizes and few amorphous carbon impurities. Intriguingly, the sheet resistance of graphene on glass is dramatically lowered down to ≈1170 Ω sq-1 at the optical transmittance ≈93%, ≈20% of that derived without the water etchant. Based on the highly conductive and optical transparent graphene on glass, a see-through thermochromic display is thus fabricated with transparent graphene glass as a heater. This work can motivate further investigations of the direct synthesis of high-quality graphene on functional glass and its versatile applications in transparent electronic devices or displays.

Discovery of 5-(pyridin-3-yl)-1H-indole-4,7-diones as indoleamine 2,3-dioxygenase 1 (IDO1) inhibitors.

Early studies demonstrated that over expression of indoleamine 2,3-dioxygenase (IDO1) in tumor microenvironment results in tumor immune escape. Herein, in order to simplify the structure of two kinds of IDO1 inhibitors from marine alkaloid, Exiguamine A and Tsitsikammamines, we designed, synthesized a series of 1H-indole-4,7-dione derivatives and evaluated their inhibitory activity in IDO1 enzyme and in IFN-γ stimulated Hela cells in vitro. The structure-activity relationship demonstrated that 5-(pyridin-3-yl)-1H-indole-4,7-dione is a promising scaffold for IDO1 inhibitors and most compounds with this core showed moderate inhibition potency at micromole level. Our further enzyme kinetics experiments reveal that these new developed compounds might act as reversible competitive inhibitors of IDO1.

[Study on the Catalytic Kinetic Spectrophotometric Determination of Trace Amounts of Iron(â ¢) and Its Reaction Mechanism].

A catalytic kinetic spectrophotometric method, which is based on the catalytic effect of Fe(Ⅲ) on the fading reaction between potassium persulfate(K2S2O8) and methyl red(MR) in the solution of 0.30 mol·L-1 hydrochloric acid, for the determination of trace amounts of Fe(Ⅲ) has been investigated. A novel detection system, Fe(Ⅲ)-HCl-K2S2O8-MR, has been developed. The optimum experimental conditions for the determination of trace amounts of Fe(Ⅲ) were found on the basis of orthogonal test. The kinetics parameters and equation of this fading reaction of MR were studied. Its reaction mechanism was discussed. The results show that there is a good linear relationship between the variation of MR absorbance at the maximum absorption wavelength of 518 nm and the concentration of Fe(Ⅲ) under the optimum experimental conditions: ln(A0/A)=1.334 1+0.001 0, the correlation coefficient is 0.999 1. The kinetic research shows that the reaction order with respect to Fe(Ⅲ) is 1 and the overall fading reaction is a pseudo-first order reaction. The apparent activation energy of the fading reaction of MR is 69.88 kJ·mol-1. Furthermore, the catalytic effects of Fe(Ⅲ) on this fading reaction is confirmed by its reaction mechanism. This novel method for the determination of trace Fe(Ⅲ) has never previously been published so far. Trace amounts of Fe(Ⅲ) can be selectively determined by this catalytic kinetic spectrophotometric method with high precision and accuracy. This method is simple and its reagents used are cheap and available. Its sensitivity is higher than that of conventional spectrophtometry with detection limit of 0.005 mg·L-1. This detection system is stable. This proposed method has been applied to the determination of trace amounts of Fe(Ⅲ) in food and water samples with satisfactory results. Relative standard deviation of the detection results is 1.18%～2.11%. Average recovery rate of the detection results is 98.0%～104.0%.

Carboxymethyl chitosan modification of cobalt-zinc bimetallic MOF for tetracycline hydrochloride removal: Exploration of the enhancement mechanism of the process.

This study synthesized a carboxymethyl chitosan-modified bimetallic Co/Zn-ZIF (CZ@CMC) with strong hydrophilicity and adsorption performance via the one-pot method. Tetracycline hydrochloride (TCH) was used as the model contaminant to evaluate the adsorption and peroxymonosulfate (PMS) activation properties of CZ@CMC. Mechanism showed that the adsorption behavior occurred through pore filling, electrostatic attraction, surface complexation, hydrogen bonding, and π-π stacking. In addition, a CZ@CMC/PMS system was constructed, which had excellent catalytic performance. The hydrophilicity and selective adsorption properties of CMC conferred a greatly accelerated CZ@CMC in catalyzing the PMS process with kobs of 0.095 min-1, in which OH, 1O2, SO4-, O2-, and Co(III) were the main ROS which quenching tests, EPR, and chemical probe experiments verified. In addition, the degradation pathways of TCH were obtained utilizing DFT and HPLC-MS and analyzed to show that the system possessed a good detoxification capacity. This work is expected to provide a green, efficient, and stable strategy to enhance the adsorption properties of catalytic materials and subsequently their co-catalytic properties.

Toward nitrogen recovery: Co-cultivation of microalgae and bacteria enhances the production of high-value nitrogen-rich cyanophycin.

The algal-bacterial wastewater treatment process has been proven to be highly efficient in removing nutrients and recovering nitrogen (N). However, the recovery of the valuable N-rich biopolymer, cyanophycin, remains limited. This research explored the synthesis mechanism and recovery potential of cyanophycin within two algal-bacterial symbiotic reactors. The findings reveal that the synergy between algae and bacteria enhances the removal of N and phosphorus. The crude contents of cyanophycin in the algal-bacterial consortia reached 115 and 124 mg/g of mixed liquor suspended solids (MLSS), respectively, showing an increase of 11.7 %-20.4 % (p < 0.001) compared with conventional activated sludge. Among the 170 metagenome-assembled genomes (MAGs) analyzed, 50 were capable of synthesizing cyanophycin, indicating that cyanophycin producers are common in algal-bacterial systems. The compositions of cyanophycin producers in the two algal-bacterial reactors were affected by different lighting initiation time. The study identified two intracellular synthesis pathways for cyanophycin. Approximately 36 MAGs can synthesize cyanophycin de novo using ammonium and glucose, while the remaining 14 MAGs require exogenous arginine for production. Notably, several MAGs with high abundance are capable of assimilating both nitrate and ammonium into cyanophycin, demonstrating a robust N utilization capability. This research also marks the first identification of potential horizontal gene transfer of the cyanophycin synthase encoding gene (cphA) within the wastewater microbial community. This suggests that the spread of cphA could expand the population of cyanophycin producers. The study offers new insights into recycling the high-value N-rich biopolymer cyanophycin, contributing to the advancement of wastewater resource utilization.

Voltammetric sensing of Cd(II) at ZIF-8/GO modified electrode: Optimization and field measurements.

In this work, a metal-organic framework/graphene oxide (MOF(ZIF-8)/GO) nanocomposite was utilized for the electroanalysis of trace level of Cd(II) after modification of a cheap graphite rod electrode (GRE). After closed circuit process on the modified electrode, the differential pulse anodic stripping voltammetry (DPASV) technique was used for measuring of Cd(II). In optimal conditions, the sensor showed a linear dependence of current with concentration range 0.1-30 ppb for Cd(II). Moreover, limit of detection 0.03 ppb were obtained. Besides good selectivity, the sensor also indicated good reproducibility (below 5%). Moreover, the sensor showed satisfactory sensing performance in river, dam and wastewater samples with recovery ranging from 97.2% to 102.4%. Additionally, possible interfering cations were examined, but no significant interference was found. For the detection of trace Cd(II) in real matrices, this sensor illustrated other good merits like high stability, rapidity and simplicity.

Insight into electrochemically boosted trace Co(II)-PMS catalytic process: Sustainable Co(IV)/Co(III)/Co(II) cycling and side reaction blocking.

A novel homogeneous electrocatalytic system was constructed by current-assisted trace Co(II) activating PMS (ECP) to remove reactive blue 19 (RB19). More than 93 % of RB19 was rapidly removed with only a trace dose, and the PMS was 98.35 % utilized during the reaction. By exploring the active species and analyzing the PMS consumption, it was found that current strongly accelerated the Co(III)/Co(II) redox cycle by providing electrons to Co(III), and inhibited the side reaction thus improving the PMS utilization. Electric energy per order was very low, only 0.26 kWh·m3. Radicals (SO4•-) and non-radicals (Co(III), Co(IV) and 1O2) participated in ECP system, in which SO4•- was dominant. By excluding the other three precursors (PMS, •OH and O2•-), the side reaction product SO5•- was identified as the source of 1O2 in ECP system. Combining chelating agent EDTA and chemical probe PMSO, Co(IV) was considered formed by single and double charge transfer. Five degradation pathways of RB19 were proposed using mass spectrometry and DFT calculation. The ecotoxicity and mutagenicity of RB19 and its transformation products were predicted using software simulation. These studies provided an interesting insights into the synergistic Co(II)-PMS systems and offered a new strategy for electrochemical processes.

Multitrack and multianchor point screw technique combined with the Wiltse approach for lesion debridement for lumbar tuberculosis.

BACKGROUND: The incidence of lumbar tuberculosis is high worldwide, and effective treatment is a continuing problem. AIM: To study the safety and efficacy of the multitrack and multianchor point screw technique combined with the contralateral Wiltse approach for lesion debridement to treat lumbar tuberculosis. METHODS: The C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR), visual analogue scale (VAS) score, oswestry disability index (ODI) and American Spinal Injury Association (ASIA) grade were recorded and analysed pre- and postoperatively. RESULTS: The CRP level and ESR returned to normal, and the VAS score and ODI were decreased at 3 mo postoperatively, with significant differences compared with the preoperative values (P < 0.01). Neurological dysfunction was relieved, and the ASIA grade increased, with no adverse events. CONCLUSION: The multitrack, multianchor point screw fixation technique combined with the contralateral Wiltse approach for debridement is an effective and safe method for the treatment of lumbar tuberculosis.

An Anode-Free Potassium-Metal Battery Enabled by a Directly Grown Graphene-Modulated Aluminum Current Collector.

Potassium (K)-metal batteries have emerged as a promising energy-storage device owing to abundant K resources. An anode-free architecture that bypasses the need for anode host materials can deliver an elevated energy density. However, the poor efficiency of K plating/stripping on potassiophobic anode current collectors results in rapid K inventory loss and a short cycle life. Herein, commercial Al foils are decorated with an ultrathin graphene-modified layer (Al@G) through roll-to-roll plasma-enhanced chemical vapor deposition. By harnessing strong adhesion (10.52 N m-1 ) and a high surface energy (66.6 mJ m-2 ), the designed Al@G structure ensures a highly smooth and ordered K plating/stripping process. Consequently, during K-metal plating/stripping, Al@G can operate at a current density of up to 4.0 mA cm-2 and cyclic capacity of up to 4.0 mAh cm-2 , with an ultralong lifespan of up to 1000 h at 0.5 mA cm-2 and stable cycling of up to 750 h under periodic current fluctuations of 0.1-2.0 mA cm-2 . In addition, a novel anode-free K-metal full-cell prototype enabled by Al@G anode current collectors is constructed, demonstrating ameliorative cyclic stability.

Bimetallic Selenide Decorated Nanoreactor Synergizing Confinement and Electrocatalysis of Se Species for 3D-Printed High-Loading K-Se Batteries.

The potassium-selenium (K-Se) battery has been considered an appealing candidate for next-generation energy storage systems owing to the high energy and low cost. Nonetheless, its development is plagued by the tremendous volume expansion and sluggish reaction kinetics of the Se cathode. Moreover, implementing favorable areal capacity and longevous cycling of a high-loading K-Se battery remains a daunting challenge facing commercial applications. Herein, we devise a Se and CoNiSe2 coembedded nanoreactor (Se/CoNiSe2-NR) affording low carbon content as an advanced cathode for K-Se batteries. We systematically uncover the enhanced K2Se2/K2Se adsorption and promoted K+ diffusion behavior with the incorporation of Co throughout theoretical simulation and electrokinetic analysis. As a result, Se/CoNiSe2-NR harvests high cycling stability with a capacity decay rate of 0.038% per cycle over 950 cycles at 1.0 C. More encouragingly, equipped with a 3D-printed Se/CoNiSe2-NR electrode with tunable Se loadings, K-Se full batteries enable steady cycling at an elevated Se loading of 3.8 mg cm-2. Our endeavor ameliorates the capacity and lifetime performance of the emerging K-Se device, thereby offering a meaningful tactic in pursuing its practical application.

Alginate production of Pseudomonas strains and its application in preparation of alginate-biomass hydrogel for heavy metal adsorption.

In this study, 7 Pseudomonas strains were isolated from a wastewater treatment plant, and the alginate production of Pseudomonas strains under different environmental conditions was evaluated. Subsequently, alginate-biomass hydrogel beads were prepared using alginate and biomass of Pseudomonas, and their adsorption performances and mechanism to Pb2+ and Cd2+ were analyzed. The results show that weakly acidic pH and 37 °C is favorable for alginate synthesis of Pseudomonas strains, and P. alcaligenes YLS18 have the highest alginate yield (29.4 mg/g). The adsorption processes of Pb2+ and Cd2+ by hydrogel beads are well described by Langmuir model, indicating that the adsorption process is monolayer. Among the biomass of these strains, P. nitroreducens YLB32 shows the highest biosorption capacities, reaching 110.7 mg/g for Pb2+ and 54.3 mg/g for Cd2+ at pH 5. Alginate-biomass hydrogel beads obtain higher adsorption capacity to Pb2+ (184.0 mg/g) and Cd2+ (92.4 mg/g), and exhibit good reusability. The adsorption mechanism of Pb2+ and Cd2+ by hydrogel beads involves physical tapping of ions, electrostatic interactions, complexation, cation exchange and precipitation. These results provide strong support for promoting alginate recovery from activated sludge and for treating heavy metal wastewater.

Taping into the super power and magic appeal of ultrasound coupled with EDTA on degradation of 2,4,6-TCP by Fe0 based advanced oxidation processes.

Chlorophenol is a widely used organic compound, and the environmental and health problems caused by it have being worsened in recent years. This study used 2,4,6-trichlorophenol (2,4,6-TCP) as the target pollutant, and employed ultrasound (US) enhanced zero-valent iron (Fe0)/EDTA/air system (FEA), namely US/FEA, to remove 2,4,6-TCP. The influence of single factor experimental conditions such as EDTA concentration, Fe0 dosage, US power, pH and pollutant concentration on the removal efficiency of 2,4,6-TCP was investigated, and the optimal reaction conditions were determined. The mechanism of reactive oxygen species (ROS) produced by US/FEA was explored. The degradation process and removal mechanism of 2,4,6-TCP in the US/FEA were discussed through the determination and analysis of intermediate products. The results showed that US could continuously activate and renew the Fe0 surface, accelerate its oxidation and corrosion process, and then continuously and stably produce sufficient amounts of Fe2+ and Fe3+. Ultrasonic cavitation effect could reduce the difficulty of O2 activation reaction, and promote the production of sufficient H2O2. The addition of EDTA made the system have a wide range of pH applications, and its performance under neutral and alkaline conditions was also superior. The ROS of US/FEA included ·OH, O2·- and Fe(IV), where Fe(IV) was the main contributor to the removal of 2,4,6-TCP. In addition, the degradation of 2,4,6-TCP had two processes including dechlorination and benzene ring opening. First, 2,4,6-TCP was dechlorinated and degraded into phenol. And then, phenol was degraded into small molecular acids by ring-opening, and finally it was mineralized into CO2 and H2O completely. US/FEA is a promising technology for high-efficiency degradation of organic matter and deep environmental purification.