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In this work, cathode materials of spent lithium-ion ternary batteries are recovered and used as metal precursor to prepare multi-metal oxides MnOx(SY) and GdMnO3(SY) via combustion method and sol–gel method, respectively. Furthermore, a series of MnOx(SY)-n and GdMnO3(SY)-n (n = 0.05, 0.10, 1.00, 4.00, n represents the dilute HNO3 concentration) catalysts are fabricated by acid treatment of MnOx(SY) and GdMnO3(SY) samples and catalytic activities of oxygenated VOCs oxidation over all the prepared catalysts are investigated. Catalytic evaluation results show that acid-treated MnOx(SY)-0.10 and GdMnO3(SY)-0.05 samples perform the optimum VOCs removal efficiency respectively, which may be attributed to their obvious enhancement of physicochemical properties. In detail, MnOx(SY)-0.10 and GdMnO3(SY)-0.05 samples exhibit the larger specific surface area, bigger amount of surface high-valence metal ions (Mn4+, Co3+, Ni3+), more abundant adsorbed oxygen species and better low-temperature reducibility, which can play a crucial role in the significant improvement of VOCs oxidation. In situ DRIFTS results imply that the possible main intermediates are -OCO, -COO and -C-O species produced during VOCs oxidation. Possible by-products are further determined via TD/GC–MS analysis.

Fine particles with the size below 1 μm are difficult to be captured with the traditional dust removal devices because of their poor charge capacity and filterability. Using the agglomeration pretreatment can realize the fine particles growth, then facilitating the capture process. In this study, a novel system with the combination of corona discharge and embedded turbulence was put forward. The results showed that the device can agglomerate the smaller particles into bigger ones, and the maximum decrease of number concentration for small particles can reach 40% in the bipolar corona discharge condition. The median diameters of fine particles can be improved by 47% maximumly in the condition of arrangement of turbulence bars and loopholes with a lower flow velocity. The simulated calculation and pilot scale test were conducted and the results were consistent with experimental conclusions.

Supported Pd-Cu NO3− reduction (NO3R) under H2 atmosphere is considered as a promising way to achieve NO3− removal directly in water through converting into N2, which is a harmless product in environment. However, desirable NO3R kinetics and N2 selectivity remain challenges. In this research, 2.5 wt% Cu and 10 wt% Pd are loaded on various oxides supports and combine with electrolytic in-situ H2 generation for NO3R. Pd10%Cu2.5%/TiO2 demonstrates a faster NO3R rate constant than Pd10%Cu2.5%/γ-Al2O3 and even greater than Pd10%Cu2.5%/CeO2. Pd10%Cu2.5%/γ-Al2O3 obtains better N2 selectivity than the other two. Crucially, the oxygen vacancies (VO) existing in TiO2 and CeO2 can reduce the nearby Cu2+ to Cu+, also Cu2+ can attract electrons from Pd0 to form Cu+ on the γ-Al2O3 surface. Verified by experiments and density functional (DFT) calculations, these Cu+ based active sites on the surface of substrates are vital for effective NO3− adsorption and high N2 selectivity.

In this work, GdMnO3 material is successfully prepared using sol-gel method and GdMn2O5/GdMnO3 materials are in-situ generated by acid treatment. These materials are investigated and applied as catalysts for oxygenated VOC complete oxidation. The evaluation results show that GdMn2O5/GdMnO3-1.00 exhibits a remarkable increase in catalytic activity (T50% = 198 °C and T90% = 225 °C) of 2-ethoxyethanol oxidation when compared with the initial sample GdMnO3 (T50% = 223 °C and T90% = none). Characterization analyses show that acid treatment can result in the significant improvement of specific surface area from 20.502 m2·g−1 to 67.952 m2·g−1, abundant surface Mn4+ content and active oxygen, excellent reducibility at low temperature in GdMn2O5/GdMnO3-1.00 sample. In-situ DRIFTS results point out that the main functional groups such as νas(OCO), νas(COO), νs(C O) are formed in the process of 2-ethoxyethanol oxidation over GdMn2O5/GdMnO3-1.00 sample and some by-products including ethanol, 2-ethoxyethyl acetate, acetic acid, carbonic acid, 2-ethoxyethyl 2-methoxyethyl ester, ethane and 1,1′-oxybis[2-methoxy-] can be produced at a reaction temperature of 200 °C. Additionally, in-situ DRIFTS studies indicate the presence of gas-phase O2 plays a vital role in facilitating 2-ethoxyethanol deep oxidation to final products.

Bisphenol A (BPA) is a harmful endocrine disruptor, sensitive and rapid quantification of BPA is highly desirable. In this work, a novel synergistic signal-amplifying electrochemical biosensor was developed for BPA detection by using a recognition probe (RP) constructed by BPA aptamer modified gold nanoparticles-loaded magnetic reduced graphene oxide (Aptamer-MrGO@AuNPs), and a signal probe (SP) constructed by BPA aptamer-complementary single-stranded DNA (ssDNA) functionalized methylene blue (MB)-loaded gold nanoparticle (ssDNA-AuNP@MBs). The RP and SP can self-assemble to form a stable RP-SP complex through complementary base pairing. The current intensity of the biosensor correlates with the number of RP-SP complexes. In the presence of BPA, the BPA aptamer can capture BPA with high selectivity and affinity, form an RP-BPA complex and dissociate the RP-SP complex to release SP, resulting in a decrease in the current signal intensity of the biosensor. A single AuNP could be loaded with multiple BPA aptamers and MBs, which improves the recognition efficiency and enhances the signal intensity. Due to the magnetic properties of MrGO@AuNPs, the magnetic separation and adsorption of RP or RP-SP complex is very convenient, enabling all reaction processes to be carried out in solution, which not only improves the mass transfer efficiency, but also simplifies the operation. Under optimal conditions, the developed biosensor had a detection limit as low as 0.141 pg/mL and had been successfully applied to the detection of real environmental water samples. Therefore, the synergistic signal amplification strategy of RP and SP has potential value in the detection of trace pollutants in the water environment.

Hydrodynamic cavitation has been a promising method and technology in wastewater treatment, while the principles based on the design of cavitational reactors to optimize cavitation yield and performance remains lacking. Computational fluid dynamics (CFD), a supplementation of experimental optimization, has become an essential tool for this issue, owing to the merits of low investment and operating costs. Nevertheless, researchers with a non-engineering background or few CFD fundamentals used straightforward numerical strategies to treat cavitating flows, and this might result in many misinterpretations and consequently poor computations. This review paper presents the rationale behind hydrodynamic cavitation and application of cavitation modeling specific to the reactors in wastewater treatment. In particular, the mathematical models of multiphase flow simulation, including turbulence closures and cavitation models, are comprehensively described, whilst the advantages and shortcomings of each model are also identified and discussed. Examples and methods of the coupling of CFD technology, with experimental observations to investigate into the hydrodynamic behavior of cavitating devices that feature linear and swirling flows, are also critically summarized. Modeling issues, which remain unaddressed, i.e., the implementation strategies of numerical models, and the definition of cavitation numbers are identified and discussed. Finally, the advantages of CFD modeling are discussed and the future of CFD applications in this research area is also outlined. It is expected that the present paper would provide decision-making support for CFD beginners to efficiently perform CFD modeling and promote the advancement of cavitation simulation of reactors in the field of wastewater treatment.

The method of enhancing mass transfer and improving reaction efficiency by confinement has attracted much attention in the electrochemical research field. In this research, to make low diffusion-limited electrochemical reactors fieldable, a new electrochemical reactor in flow-through mode was established with the mass-produced Ti/RuO

The key structure of the interface between the spike protein of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and human angiotensin-converting enzyme 2 (hACE2) acts as an essential switch for cell entry by the virus and drugs targets. However, this is largely unknown. Here, we tested three peptides of spike receptor binding domain (RBD) and found that peptide 391-465 aa is the major hACE2-interacting sites in SARS-CoV-2 spike RBD. We then identified essential amino acid residues (403R, 449Y, 454R) of peptide 391-465 aa that were critical for the interaction between the RBD and hACE2. Additionally, a pseudotyped virus containing SARS-CoV-2 spike with individual mutation (R454G, Y449F, R403G, N439I, or N440I) was determined to have very low infectivity compared with the pseudotyped virus containing the wildtype (WT) spike from reference strain Wuhan 1, respectively. Furthermore, we showed the key amino acids had the potential to drug screening. For example, molecular docking (Docking) and infection assay showed that Cephalosporin derivatives can bind with the key amino acids to efficiently block infection of the pseudoviruses with wild type spike or new variants. Moreover, Cefixime inhibited live SARS-CoV-2 infection. These results also provide a novel model for drug screening and support further clinical evaluation and development of Cephalosporin derivatives as novel, safe, and cost-effective drugs for prevention/treatment of SARS-CoV-2.

A nitrogen removal system integrating partial nitrification, anaerobic ammonium oxidation (Anammox) and endogenous denitrification (PAED) was established in a sequencing batch reactor (SBR) for treating low nitrogen sewage (approximately 40 mg L−1 ammonia-nitrogen). The impact of sulfate on PAED sludge was investigated in five identical SBRs, fed with different levels of sulfate (0, 50, 100, 200 and 400 mg L−1). Ammonia oxidation was improved by the addition of Results showed that the sulfate addition in low concentration of sulfate (≤50 mg L−1), but was profoundly suppressed by higher levels of sulfate. Sulfate feeding enhanced both total nitrogen removal by Anammox and endogenous denitrification, with the abundance of Candidatus Kuenenia increasing to 4.39% in 400 mg L−1 sulfate from 0.83% in the control reactor, and Denitratisoma increasing to 6.35% from 2.77%. The results proved the feasibility of the PAED system in treating low nitrogen sewage with sulfate, which also enhanced the nitrogen-sulfate interaction.

In order to recycle and reuse metal resources from spent ternary lithium batteries, manganese-based composite perovskite is synthesized from waste by citrate sol–gel method and is used as catalyst for VOC removal. The characterization results indicate that manganese-based composite perovskite catalyst has a crystal phase of LaMnO 3 , and owns higher specific surface area, better reductivity at low temperature, more abundant Mn 4+ ions and lattice oxygen species than pure manganese perovskite catalyst. The results of catalytic evaluation show that manganese-based composite perovskite catalyst prepared from waste performs better catalytic performance of toluene oxidation in comparison with pure manganese perovskite. The effects of other cations existing in spent ternary lithium batteries are further investigated. The results imply that the catalytic performance can be significantly inhibited with the introduction of lithium ions, while appropriate amounts of copper, nickel and cobalt ions can improve the catalytic performance over pure manganese perovskite catalysts.

This paper focuses on the problem of sampled-data stabilization for a class of low-order lower-triangular nonlinear systems with large input delays. A new predictor-based multi-rate sampled-data control scheme is proposed to guarantee that the resulting system is globally strongly stable under some assumptions. Compared with the existing methods, the present strategy just needs to know the approximate prediction of state variables, and the stabilizing performance of a given continuous-time feedback controller can be preserved at the sampling instants. It is noted that the proposed controller takes the form of a power series. Its truncation at a finite order is regarded as approximate controller which is proved to be effective in the practical implementation. Two simulation examples are finally given to illustrate the advantages and effectiveness of the proposed control scheme.

Polypyrrole (PPy) nanosilk, nanowire array and nanorod array films are synthesized on carbon cloth substrate through electrochemical polymerization by only controlling the concentration of p-toluenesulfonate acid (TsOH) in electrolyte. The nanostructured films exhibit much better electricity generation performances in photoelectrochemical cell in comparison with flat film being as cathode due to their high surface areas and low combined series resistances. The optimized synthesized films are further applied in an efficient dual rotating disk photo fuel cell to treat real textile wastewater with the initial chemical oxygen demand (COD) and conductivity of 108 ± 5 mgO2 L−1 and 11600 μS cm−1, respectively, for simultaneous electricity generation. With nanosilk film as cathode, 0.44 V open circuit voltage and 2.00 mA short circuit current are obtained, the maximum output power reaches 0.22 mW. Similar results are also obtained with nanowire and nanorod arrays. Stable currents can be measured during 4 h treatment when the output voltage is 0 (short circuit condition), 0.15 and 0.25 V with any film. The COD is removed to 28 mgO2 L−1 under short circuit condition with nanosilk or nanowire cathode. However, they are 36 and 47 mgO2 L−1, respectively, when nanorod and flat cathodes are used. Moreover, the effects of pH and rotating speed are also investigated in this research.

The high-efficient electrochemical hydrogen evolution reaction (HER) is a promising pathway to provide clean energy. An electrocatalyst was computer-aided designed with Mo isolated single atoms (Mo-ISA) supported on heteroatom S, N-codoped carbon having excellent HER performance. Here, by performing comprehensive density functional theory (DFT) computations, we investigated the influence of the N dopent concentration and the sites of S atom doping on the HER performance. Our computed results demonstrate that the Mo-ISA/N1C and Mo-ISA/S6N1C catalysts possess good stability and high HER reactivity. Moreover, the interactions between hydrogen and the Mo atoms could be controlled by the N dopent concentration on carbon support, and the Mo-ISA/N1C catalyst showed best HER reactivity. In particular, the S atom was introduced into Mo-ISA/N1C at the S6 site showing an enhanced HER performance due to the competitive effect of the S-induced tensile strain and charge transfer. Our DFT computations open up new opportunities for application of S, N-codoped Mo-based high-efficient catalysts for HER.

The occurrence and accumulation of antibiotics in wastewater treatment plant have been a growing concern. Erythromycin (ERY), a representative class of Macrolides, was picked out to investigate the long-term effects on anaerobic ammonium oxidation (Anammox) process in this study. Anaerobic ammonia-oxidizing bacteria (AAOB) was initially inhibited when suffered the ERY in 0.001 and 1 mg L−1, but rapidly recovered after 12 and 10 days’ exposure, respectively. The restoration time of AAOB under the stress of ERY in 1 mg L-1 was shorter than that in 0.001 mg L−1. Significant suppression without recovery was observed as the concentration of ERY was increased to 10 mg L−1. The deterioration was continued with the increasing concentrations. However, the pace of deterioration was tended to ease in each phase. Therefore, it can be speculated that Anammox microorganisms resisted the biotoxicity of ERY to some extent via gene mutations or secreted more extracellular polymeric substances.

A series of 3DOM zinc ferrites and silica composites were prepared and applied on the hydrogen sulfide (H2S) removal at 500 °C. With ∼230 nm-sized macropores and 15 nm-sized walls, the morphology analysis showed the as-prepared ZnFe2O4-SiO2 materials were conducted as a typical 3DOM structure. As a solifidation agent, silica significantly influenced not only the composites structure, which induced the homogeneity and stability of 3DOM structure, but also the desulfurization behavior, in which the active phase utilization decreased if the compounded silica amount was too high or too low. Anyway, the 3DOM sorbents exhibited remarkable desulfurization performance due to the unique structure features with high surface area, nano zinc ferrite particles, well arranged macropores with interconnected mesopores, which significantly enhances gaseous reactant diffusion during sulfidation compared with those of bulk sorbent. Sulfates could be formed during both sulfidation and regeneration process, while Fe2(SO4)3 in sulfided sample and ZnSO4 in regenerated sample. 3DOM structure and silica participation enhanced the breakthrough capacity of 50 wt% ZnFe2O4 compounded sorbent and maintained higher desulfurization capacities upon multiple sulfidation/regeneration cycles more ascribed to its special structural feature.

Iron ore sintering is a major source of gaseous and particulate pollutants emission in iron smelt plant. The aim of present study is to characterize the volatile organic compounds (VOCs) emission profiles from iron ore sintering process. Both sinter pot test and sinter simulation experiment were conducted and compared. Out results showed that sinter process produced large quantity of VOCs together with NOx and SO2. VOCs and NO were produced simultaneously in sinter pot test from 3 to 24 min after ignition, flowed by SO2 production from 15 min to the end of sintering. Total VOCs (TVOC) concentration in sinter flue gas was affected by the coal and coke ratio in sinter raw material. The maximum TVOC concentration was 34.5 ppm when using 100% coal as fuel. Sinter simulation experiments found that the number of VOCs species and their concentrations were found by sinter temperature. The largest VOCs species varieties were obtained at 500 °C. Benzene, toluene, xylene and ethylbenzene were major VOCs in sinter flue gas based on the results from both simulation test and sinter pot. It thus demonstrated that in addition to NOx, SO2 and metal oxide particles, sinter flue gas also contained significant amount of VOCs whose environmental impact cannot be ignored. Based on our work, it is timely needed to establish a new VOC emission standard for sinter flue gas and develop advanced techniques to simultaneously eliminate multi-pollutants in iron ore sinter process.

This paper focuses on the exponential synchronization problem of complex dynamical networks (CDNs) with time-varying network topology via event-triggered communication strategy. The definition of a new time-varying network topology, called cooperatively directed spanning tree topology, is first given based on the integral of time-varying Laplacian matrix. This topology does not require the network constantly connected. In other words, the network topology is allowed to be disconnected at all times, but only the integral of the Laplacian matrix of the network graph is required to contain directed spanning tree over a period of time. Moreover, in order to achieve the exponential synchronization for CDNs under the cooperatively directed spanning tree topology, a sufficient condition is derived by the virtues of algebraic graph theory, event-triggered communication strategy, matrix inequality and the special Lyapunov stability analysis method. Additionally, event-triggered communication strategy can avoid continuous communication, which can reduce the communication load and energy consumption. The Zeno behavior is excluded as well by the strictly positive sampling intervals based on the upper right-hand Dini derivative, and thus to avoid infinite triggers. Finally, simulation examples are given to show the effectiveness of the proposed exponential synchronization criteria.

Developing low-cost, high adsorption capacity, and recyclable mercury sorbents is an important step for control of mercury in coal-fired flue gas. However, few sorbents meet all the requirements. Herein, we explore the adsorption behavior and oxidation mechanisms of mercury on 2D Ti2CO2 (MXenes) monolayer and defective Ti2CO2 monolayer with an Ov (Ov-Ti2CO2) through first-principles computations based on density functional theory (DFT). Our calculation results show that Hg0 adsorption on Ti2CO2 and Ov-Ti2CO2 monolayers are mainly physisorption and chemisorption mechanisms, respectively. Moreover, the presence of a single oxygen vacancy on Ti2CO2 monolayer can improve the interaction between the mercury and Ov-Ti2CO2 monolayer, thereby enhancing the adsorption energy of mercury by 66 kJ/mol. Hg0 has a strong interaction with Ti atom on Ov-Ti2CO2 monolayer by the atomic orbital hybridization and overlap. The adsorption of HgO molecule on Ti2CO2 and Ov-Ti2CO2 monolayers are chemisorption processes. Furthermore, electron density difference analysis indicates that the remarkable charge accumulation across the interface is closely related to the strong interaction between HgO molecule and Ti2CO2 or Ov-Ti2CO2 monolayers. The three-step reaction processes (Hg0 → Hg(ads) → HgO(ads) → HgO) are taken place on Ti2CO2 and Ov-Ti2CO2 monolayers, resulting in the formation of gaseous HgO molecule. The energy barrier for the Hg0 oxidation reaction step on Ov-Ti2CO2 monolayer (54.85 kJ/mol) is about half of that on Ti2CO2 monolayer (104.73 kJ/mol). The desorption steps of the resultant HgO molecule from Ti2CO2 and Ov-Ti2CO2 monolayers are the rate-determining steps, which need external energies of about 119.3 and 183.2 kJ/mol, respectively.

In this study, the impacts of heavy metals (1 mg L−1) on the nitrogen removal, bioactivity of anaerobic ammonia-oxidizing bacteria (AAOB) and the microbial community of anaerobic ammonium oxidation (Anammox) process were investigated. It was observed that short-term exposure in Cu (II) and Zn (II) both improved AAOB bioactivity, while long-term exposure significantly lowered the nitrogen removal to 0.218 and 0.302 kg m−3 d−1, when treated the wastewater with 100 mg L−1 nitrogen under 14–16 °C. Fe(II) had slight impact on Anammox in short-term experiment but deeply enhanced nitrogen removal during the long-term contact, and finally increased the that to 0.58 kg m−3 d−1. The impact on Anammox was Cu(II) > Zn(II) > Fe(II). Cu(II) and Zn(II) lowered the share of Candidatus Kuenenia to 3.32% and 3.80%, while Fe(II) improved that to 11.30% from 7.99%. Extracellular polymeric substance in biofilm had prominent iron adsorption capacity, which was the key factor that help AAOB resist Fe(II).

γ-MnO2, SmMnO3, and γ-MnO2/SmMnO3 catalysts were prepared by facile methods, wherein the SmMnO3 (SMO) perovskite was synthesized through one-step calcination and the γ-MnO2/SmMnO3 was formed by an in situ growth of γ-MnO2 on the surface of SMO. These materials ware characterized by XRD, SEM-mapping, N2-adsorption, XPS and H2-TPR to investigate their textural properties. Compared with that of SMO and γ-MnO2, the γ-MnO2/SMO shows better performance for catalytic oxidation of aromatic VOCs in wet air (10 vol.%), which may be attributed to its higher surface molar ratio of lattice oxygen to adsorbed oxygen (Olatt/Oads) and better low-temperature reducibility. Besides, for γ-MnO2/SMO catalyst, a successive oxidation route and the inner principle of BETX (benzene, ethylbenzene, toluene, and o-xylene) oxidation were also revealed via various tests and a comprehension of dynamics investigation. Meanwhile, the experiments under simulated realistic exhaust conditions displayed that the γ-MnO2/SmMnO3 is also a good catalyst with high stability for aromatic VOCs oxidation, and fulfilled endurability to high humidity (20 vol.%).

A selective separation-recovery process based on tuning organic acid was proposed to the resource recycling of spent lithium-ion batteries (LIBs) for the first time. The low-cost preparation of CoFe2O4, reuse of waste acid and recovery of Li can be realized in this process, simultaneously. Li and Co in spent LIBs can be leached efficiently using citric acid as a leaching agent, and separated effectively from leaching solution by tuning oxalic acid content. The results from the characterizations of the prepared CoFe2O4 (CoFe2O4-LIBs) show that it possesses higher ratio of Co(II)/Co(III) and Fe(II)/Fe(III), larger surface specific area and more number of acid sites in comparison with pure CoFe2O4. Besides, CoFe2O4-LIBs was used to activate peroxymonosulfate (PMS) for the degradation of bisphenol A (BPA). Interestingly, its degradation performance is superior to that of pure CoFe2O4 and the related Co-based catalysts. The excellent degradation performance can be maintained in presence of inorganic ions (e.g., C l − , HC O 3 − , H 2 P O 4 − and N O 3 − ) with high concentration or humic acid. Moreover, surface-bound S O 4 ∙ − is considered as the main reactive species for the degradation of BPA. More importantly, CoFe2O4-LIBs can be readily recycled by using an external magnet and own superior ability of regeneration.

A Fenton-like catalyst comprising of hydrophilic mesoporous carbon (HMC) and ferric ions was found very efficiently in degradation organic pollutants under visible light irradiation in the presence of H2O2. HMC with graphene domains and plenty of oxygen containing groups such as carboxyl groups can cooperate with ferric ions to form a visible light active Fe(III)-HMC configuration. Fe(III)-HMC showed obviously enhanced phenol degradation and mineralization efficiencies than that in dark condition. Acidic condition (pH = 3) is not only more superior in phenol degradation but also in iron leaching in comparison with the case at basic conditions (pH = 4.5–7.0) for Fe(III)-HMC. Total organic carbon (TOC) removal efficiency of five typical organic pollutants show that visible light active Fe(III)-HMC catalyst is more efficient than homogeneous Fenton reagents FeSO4/H2O2 excluding the temperature effect. Electron spin resonance (ESR) and electrochemical measurements reveal that the presence of active phenoxyl radicals and ligand to metal charge transfer (LMCT) facilitates the cycling of Fe(III)/Fe(II) and inhibit the side reaction via Haber-Weiss reaction. ·OH radicals rather than O2− and OOH were proved as the predominantly active oxidant. The proposed Fe(III)-HMC configuration activated by visible light opens up a new strategy for carbon based materials and iron species in Fenton-like chemistry.

Supercritical water oxidation (SCWO) of 2-, 3- and 4-nitroaniline (NA) was investigated under residence time of 1–6 min, pressure of 18–26 MPa, temperature of 350–500 °C, with initial concentration of 1 mM and 300% excess oxygen. Among these operating conditions, temperature and residence time played a more significant role in decomposing TOC and TN than pressure. Moreover, the products of N-containing species were mainly N2, ammonia and nitrate. When temperature, pressure and retention time enhanced, the yields of NO3− and org-N were reduced, the amount of N2 was increasing, the proportion of NH4+, however, presented a general trend from rise to decline in general. The experiment of aniline/nitrobenzene indicated that TN removal behavior between amino and nitro groups would prefer to happen in the molecule rather than between the molecules, therefore, the smaller interval between the amino and nitro group was the more easily to interreact. This might explain the reason why TN removal efficiency was in an order that 2-NA > 3-NA > 4-NA. The NH4+/NO3− experiment result demonstrated that ammonia and nitrate did convert into N2 during SCWO, however, the formation of N2 was little without auxiliary fuel. Density functional theory (DFT) method was used to calculate the molecular structures of 2-, 3- and 4-NA to further explore reaction mechanism, which verified that amino group was more easily to be attacked than nitro group. Based on these results, the conceivable reaction pathways of 2-, 3- and 4-NA were proposed, which contained three parts, namely denitrification, ring-open and mineralization.

To avoid the potential secondary metal pollution leached from Fenton-like catalysts and use less or no external chemicals supply, we develop an all-carbon based visible light active photo-electro-Fenton-like (PEF) cell to in-situ generate highly active •OH radical for environmental remediation. In this cell, the mesoporous carbon coated graphite felt (MesoC/GF) cathode could effectively produce H2O2 by electrochemical reduction of oxygen. Graphitic carbon nitride (g-C3N4) with visible light photocatalytic activities acts as an efficient metal-free Fenton-catalyst for H2O2 activation to produce •OH radical under visible light irradiation. The different cell parameters such as applied voltage, photocatalysts dosage and pH condition have been investigated for phenol removal in aqueous solution. This metal-free visible light active PEF cell shows excellent mineralization efficiency of stubborn phenol with high stability and its performance of phenol removal efficiency is much higher than that of the g-C3N4 only photocatalysis cell and MesoC/GF only electrolysis cell. Moreover, our PEF cell presents comparable or even better Fenton-catalytic activities than the similar electro-Fenton cell using MesoC/GF and homogeneous Fe2+ ion. These results demonstrate our all-carbon based PEF cell without external chemicals supply is promising for environmental remediation.

A pre-treatment/treatment/post-treatment multiple functional dielectric barrier discharge (DBD) plasma is developed with different γ-Al2O3 based catalysts packed in this research to deeply mineralize styrene and reduce by-products generation. NiO/γ-Al2O3 is packed in the first pre-treatment cell to effectively destroy the branched chains in styrene and weaken the benzene rings. TiO2/γ-Al2O3 is packed in the second treatment cell due to their high catalytic oxidation activity to mineralize the generated aromatic compounds thoroughly. Finally, bare γ-Al2O3 is packed in the last post-treatment cell to reduce the concentrations of by-products including O3 and NO generated by air over oxidation. The combinations of these three catalysts are optimized through the treatment of 3000 mg m−3 styrene at specific input energy of 189 J L−1. In comparison with single TiO2/γ-Al2O3 packed reactor with the total discharge length of 8 cm, the selectivity of CO2 can be significantly improved from 33% to 62% when the first 2 cm TiO2/γ-Al2O3 is replaced by NiO/γ-Al2O3. Furthermore, the concentrations of O3 and NO in outlet can also be effectively reduced from 8.44 mg L−1 and 81 mg m−3 to 3.72 mg L−1 and 25 mg m−3, respectively, when the last 2 cm TiO2/γ-Al2O3 is replaced by bare γ-Al2O3. The effects of specific input energy and styrene initial concentration are also investigated.

A highly efficient nanoporous non-doped BiVO4 photoelectrode with high photocurrent and low onset potential for photoelectrochemical water splitting was achieved by using molecular catalyst and amorphous TiO2 stabilization layer. This BiVO4 photoelectrode co-catalyzed by molecular catalyst of Ir-COOH exhibits the photoelectrochemical performance comparable to the limitation values obtained in Na2SO3 sacrifice agent. Interestingly, the BiVO4/Ir-COOH exhibits more efficient interface charge transfer than BiVO4/IrOx as measured by intensity modulated photocurrent spectroscopy (IMPS) and intensity modulated photovoltage spectroscopy (IMVS) although the Ir-COOH molecular catalyst shows much lower electrochemically catalytic activities than the state-of-the-art IrOx nanoparticles for water splitting. The Ir-COOH/BiVO4 was further stabilized by double amorphous TiO2 layers with little impact on charge transfer. In all, it is promising to achieve high efficiency water splitting by using molecular catalysts to co-catalyze nanostructure photoelectrodes with short diffusion length and such system can be stabilized by amorphous TiO2 layer.

A facile transportation fuel reductive and extractive desulfurization process is studied using polyethylene glycol as extraction solvent, which is economical and environmental friendly, and sodium borohydride as reductant in this work. Several important parameters including sodium borohydride and nickel chloride dosage, stirring rate, temperature and polyethylene glycol/oil volume ratio are investigated. The total sulfur desulfurization efficiency for the simulated fuel reaches nearly 97% in this process after 1 h reaction at the temperature of 10 °C with sodium borohydride/sulfur molar ratio = 15, nickel chloride/sulfur molar ratio = 3, polyethylene glycol/oil volume ratio = 1. Furthermore, the desulfurization efficiency can be enhanced to 99% in a two-step desulfurization process. All components were detected by GC or GC-MS, and the possible desulfurization mechanism is deduced. The results show that sulfur compounds can be removed by direct desulfurization. The desulfurization performance of recycled polyethylene glycol and regenerated polyethylene glycol was also investigated and the desulfurization efficiency was 92% and 90% respectively, indicating polyethylene glycol can be regenerated in this process. Finally, actual transportation fuels (e.g. gasoline, diesel) were investigated and it revealed that polyethylene glycol and sodium borohydride can be applied in actual fuel extractive and reductive desulfurization.