Search

Poly ionic liquid s PIL are common precursors for heteroatom doped carbon materials. Despite a relatively higher carbonization yield, the PIL to carbon conversion process faces challenges in preserving morphological and structural motifs on the nanoscale. Assisted by a thin polydopamine coating route and ion exchange, imidazolium based PIL nanovesicles were successfully applied in morphology maintaining carbonization to prepare carbon composite nanocapsules. Extending this strategy further to their composites, we demonstrate the synthesis of carbon composite nanocapsules functionalized with iron nitride nanoparticles of an ultrafine, uniform size of 3 5 nm termed FexN C . Due to its unique nanostructure, the sulfur loaded FexN C electrode was tested to efficiently mitigate the notorious shuttle effect of lithium polysulfides LiPSs in Li S batteries. The cavity of the carbon nanocapsules was spotted to better the loading content of sulfur. The well dispersed iron nitride nanoparticles effectively catalyze the conversion of LiPSs to Li2S, owing to their high electronic conductivity and strong binding power to LiPSs. Benefiting from this well crafted composite nanostructure, the constructed FexN C S cathode demonstrated a fairly high discharge capacity of 1085 mAh g 1 at 0.5 C initially, and a remaining value of 930 mAh g 1 after 200 cycles. In addition, it exhibits an excellent rate capability with a high initial discharge capacity of 889.8 mAh g 1 at 2 C. This facile PIL to nanocarbon synthetic approach is applicable for the exquisite design of complex hybrid carbon nanostructures with potential use in electrochemical energy storage and conversion

The Liangzhu Culture (5300–4300 cal. a BP) has been regarded as the culmination of the Neolithic Age in the Yangtze Delta and as an archaic state. However, the reason behind the collapse of the Liangzhu Culture remains controversial. Some scholars attributed it to social conflicts or foreign invasions, while others suggested that environmental deterioration, such as cold episodes, inundation and palaeo-typhoon events, disrupted the civilization. Notably, the yellowish silty sediments widely overlying the Liangzhu group sites have been presumed to be one of the vital clues to resolving these issues. The process and cause of their formation are key to understanding the decline in the Liangzhu Culture. In this study, two typical profiles composed of the Liangzhu cultural layer and yellowish silty sediments were collected in Liangzhu Ancient City. Multiple proxies, including pollen, phytoliths and diatoms, along with radiocarbon and optically stimulated luminescence dating and synthesized geochemical evidence from different sediments, were applied to reconstruct ecological and hydrological changes and discuss their linkage to cultural collapse. The regional ecology was typical freshwater wetlands during 4800–4400 cal. a BP, which facilitated rice farming and large-scale architectural engineering in Liangzhu Ancient City. Evidence from microfossils and dating of the yellowish silty sediments indicated that Liangzhu Ancient City was significantly affected by seawater after abandonment during 4300–3400 cal. a BP. Furthermore, geochemical evidence, including trace element and Sr-Nd isotopic compositions, suggested that the primary provenance of the yellowish silt was a mixture of sediments from the Qiantang River, East China Sea, Yangtze River and Yellow River, which had been transported to Liangzhu Ancient City by the Yellow Sea Coastal Current and a marine transgression. Therefore, based on evidence from archaeological sites and numerical simulation in the Yangtze Delta, it was supposed that the short-term accelerated relative sea-level rise at approximately 4400 cal. a BP caused a marine transgression around Taihu Lake, formed a large range of yellowish silty sediments, destroyed rice farming production, and ultimately led to the collapse of the Liangzhu Culture.

To simultaneously improve the removal of nitrogen and phosphorus from wastewater with a low C/N ratio and reduce excess sludge production, in this paper, excess sludge ultrasound-hydrolysis acidification (UHA) pretreatment was coupled with the anaerobic-anoxic-oxic (AAO) process to provide carbon source and enhance biological nitrogen removal performance, and the experimental results can be summarized as follows. First, the total nitrogen (TN) concentrations in the effluent of the system decreased from 16.94 mg/L to 5.74 mg/L, and the removal rate of TN increased by 25.5%. In addition, the concentrations for ammonia nitrogen (NH3 -N) in the system decreased 12.59 mg/L, and the removal rate of this index increased by 29.0%. Furthermore, the specific oxygen uptake rate (SOUR) in the anoxic zone increased significantly because the application of UHA products enhanced the microbial activity, and the addition of UHA products had an effect on the microbial community structure in the system. The amounts of denitrifying bacteria such as Betaproteobacteria and Alphaproteobacteria also increased, which enhanced the nitrogen removal efficiency of wastewater biological treatment. PRACTITIONER POINTS: Treatment of excess sludge in UHA device as an additional carbon source. Nitrogen removal efficiency was greatly improved after adding UHA products. Input of UHA products enhanced microbial activity in AAO system. Denitrifying bacteria increased with the addition of UHA products.

The addition of Fe3+ to TiO2 is one of the effective methods to inhibit the recombination of photogenerated electrons and holes and thus improve the photocatalytic activity of TiO2. The effect of PVDF-PVP-TiO2-FeCl3 (PPTFe) membrane filtration-photocatalytic system on the removal of trace concentration of sulfadiazine (SD) in water was evaluated. A two-factor four-level experiment was established to optimize 16 self-made modified membranes. The optimal membrane was then characterized in seven tests (SEM, EDS, membrane pure water flux, contact angle, porosity, mean pore size, ATR-FTIR), resulting in the optimal ratio (PPTFe membrane with 1.2 wt%TiO2 and 0.8 wt%FeCl3). Compared with the original membrane, the pore number, pore size, permeability, and hydrophilicity of the PPTFe membrane were all enhanced. The removal efficiency (92.63%) of SD by PPTFe membrane filtration-photocatalysis system was investigated. The reaction rate (0.0214 min−1) of the removal SD of the system was determined according to the pseudo-first-order kinetic model. The removal performance of membrane type, pH, and water quality parameters (Cl−, SO42−, NO3−, HA) on PPTFe membrane filtration-photocatalytic system were also made a deep inquiry. The results reflected that acidic conditions (pH = 3) were beneficial to SD removal, the presence of Cl−, SO42−, and HA could inhibit SD removal, while the existence of NO3− was unaffected. Furthermore, the removal rate of SD in the actual water body was displayed well in this system. Finally, the possible photocatalytic degradation mechanism was proposed. Graphical abstract

The random-branched and the star-like branched polystyrenes were prepared by atom transfer radical polymerization (ATRP). Then the random-branched polystyrene and star-like polystyrene were blended...

Zooarchaeology studies the human-animal interactions over long periods, and can be used to evaluate the sustainable exploitation of animal resources. Sika deer (Cervus nippon), a National Class Ⅰ protected wild animal species of China, used to be commonly found at Neolithic sites across China. In the Yangtze River region, although the Neolithic faunal assemblages show diversity in deer species, sika deer has always been one of the most important components. This research aims at discussing the exploitation of the environmental resources via the hunting strategy of sika deer at Tianluoshan, a Neolithic site in the lower Yangtze River region. The cull pattern and sex ratio of sika deer are reconstructed to display the pattern of prey selection. The results show a specific pattern targeting larger individuals including adults and juveniles, and targeting male over female. This pattern is able to maximize the yield, and keep the deer population sustainable. The sustainable hunting of sika deer probably is why the Tianluoshan site lasted for nearly a thousand years, during which sika deer had been a major prey for meat.

The effective control of eutrophication caused by algae blooms is still the focus of global attention. The traditional dissolved air floatation process for algae removal has a low adhesion efficiency between bubbles and algal cells and a low removal efficiency of organic pollutants. Aiming to address these defects, this study set up an ozone microbubble-enhanced air flotation experiment to explore the removal trends of algal cells and algal organic matter (AOM) pollution. In contrast to traditional air flotation, this approach targets the removal of various forms of AOM after algal cell damage. The highest removal rates of algal cells, extracellular microcystin (Mc), intracellular Mc-lr and total Mc-lr were 96.6%, 60.1%, 95.2% and 93.7%, respectively. Compared with the traditional process, the absorption rate and utilization rate of ozone were increased by 41.9% and 46.2%, respectively. The removal effect of AOM was also greatly improved, and ozone microbubbles enhanced the removal of aromatic protein-like substances and high-molecular-weight fulvic acid, humic acid and humic substances. The advantageous synergistic effect of ozone and microbubbles on algae removal was analyzed by exploring the enhanced air flotation removal mechanism of ozone microbubbles' enhanced air floatation removal. Good vacuole adhesion and strong oxidation caused by ozone microbubbles jointly guaranteed a good removal rate of AOM. The enhanced air flotation process with ozone microbubbles has high feasibility and a good effect, can effectively remove algal cells and algal pollutants, and has great potential in algal removal and control of water eutrophication.

As a critical air dissolving system, the performance of air flotation equipment directly determines the adhesion efficiency and pollutant removal efficiency of air flotation processes. The factors affecting the performance of air flotation equipment and the relationships between equipment performance and pollution removal efficiency were studied. The results show that when the dissolved gas pressure was 0.4 MPa and the air intake rate was 24 mL/min, the dissolved gas efficiency of the equipment reached its highest value of 55%, the average particle size of bubbles was maintained at 24 µm, and the dissolved oxygen (DO) content significantly increased. When the dissolved gas pressure was 0.4 MPa, the air intake rate was 24 mL/min, and the coagulant dose was 6 mg/L; the removal rates for turbidity, chlorophyll-a, total organic carbon (TOC), and UV absorbance at 254 nm (UV

Odor problems are challenging issues in water treatment. Advanced oxidation has a significant degradation effect on these odors; however, some issues, such as oxidant residues and disinfection byproducts, exist in the use of advanced oxidation in actual water treatment. Because of the above issues, a combined advanced oxidation process has emerged-the UV/H

Taking advantages of reaction composite brazing, transient liquid phase bonding (TLP) and partial transient liquid phase bonding (PTLP), a novel process with the characteristics of low-temperature bonding and high-temperature resisting was developed for joining Cf/SiC composite to GH3044 alloy by using (Cu-Ti) + C + Ni mixed powder filler. Under the bonding temperature (980 °C), the reaction between the liquid Cu-Ti alloy and C particles (reaction composite mechanism), composition homogenizations between the joining layer and Ni particles (PTLP mechanism) as well as Ni-based substrate (TLP mechanism) occurred to complete the transformation (Cu,Ti)l + Cs + Nis → TiCs + (Cu,Ni)s. Thereby, a joint with high-temperature resistance and excellent mechanical properties was obtained in relatively short holding time. The melting-point of the joint (1050 °C) was obviously higher than that of Cu-Ti alloy (898 °C) in the filler. The bonded joints exhibited shear strengths of 229, 225 and 104 MPa at room temperature, 600 °C and 1000 °C, respectively.

In this study, a novel Ag–Ti reactive composite brazing technology was employed to join carbon fiber reinforced carbon matrix composite (C/C) to Nickel-based superalloy GH3044. The microstructural evolution mechanism and the effects of process parameters on the microstructures and shear strength of the brazed joints were investigated systematically. The results showed that, during the brazing holding stage, Ti (α-Ti) in the liquid phase would convert to β-Ti (above 1020°C) or react with Ag formed AgTi (below 1020°C). Solid phase β-Ti or AgTi inhibited the loss of the molten filler material, thus forming a thicker interlayer, which was beneficial to relieve the residual stress of the joints. After brazing, an Ag matrix composite interlayer reinforced by in situ synthesized phases and a few residual Ti particles could be obtained. Notably, the reinforcing phases were various with different brazing parameters. Under weaker parameters (lower Ti content, lower temperature and shorter holding time), the reinforcing phases were mainly in situ synthesized AgTi phase and residual Ti particles, with which the Ag matrix composite interlayer had good plasticity and low coefficient of thermal expansion. As a result, the residual stress of the joints was further effectively relieved. Under stronger parameters, the reinforcing phases were mainly brittle phases Ti2Ni and Cr1.93Ti1.07, which increased the brittleness of the composite interlayer. The maximum shear strength of the joints reached 45.8 MPa brazed at 1020°C for 30 min using Ag–20Ti (Wt.%).

The countercurrent–cocurrent dissolved air flotation (CCDAF) process is a new type of air flotation process integrating countercurrent collision and cocurrent flow adhesion processes. The structural form of the CCDAF tank and its process parameters are the required conditions to achieve countercurrent collision and cocurrent adhesion. In this study, eight CCDAF tank process models were established with a flow rate of 0.5 m3/h. Flow field numerical simulation and process optimization of a CCDAF tank was conducted using Fluent software. The simulation results show that the optimal conditions for the CCDAF process are as follows: contact zone ascending velocity 10 mm/s, separation zone separation velocity 1.5 mm/s, dissolved gas pressure 0.45 MPa, and recirculating dissolved-gas distribution ratio R1/R2 1:1. Under these operating conditions, the flow state in the flotation tank is the most stable and the gas in the contact zone is evenly distributed. According to the simulation results, a 5 m3/h pilot plant was built. The structural dimensions were: B × L × H = 1,020 mm × 1,300 mm × 1,350 mm. The test results show that the CCDAF has a significant decontamination effect and is clearly superior to the cocurrent flow DAF process and countercurrent flow DAF process.

Enoxacin (ENO) is widespread in water because it is commonly used as a human and veterinary antibiotic. However, little effort has been dedicated to revealing the transformation mechanisms of ENO destruction using ClO

Seasonal cyanobacterial blooms in eutrophic water releases algal organic matter (AOM), which contains large amount of dissolved organic nitrogen (DON) and is difficult to be removed effectively by conventional treatment processes (e.g., coagulation and sand filtration) because of its high hydrophilicity. Moreover, N-nitrosodimethylamine (NDMA) can be generated by the reaction of AOM with disinfectants in the subsequent disinfection process. In this study, the formation of NDMA from different AOM components was explored and the control of algal-derived NDMA precursors by UV/H

In this paper, the membrane filtration-photocatalytic coupling process was used to explore the mechanism and removal effect of trace concentrations of sulfadiazine (SD) in drinking water. First, 8 kinds of ultrafiltration membranes were successfully prepared, and their performance was verified by scanning electron microscopy and measurement of the contact angle, membrane pure water flux, porosity and average pore size. The results showed that the best-performing membranes were the PVDF-PP-TiO2-DA (dopamine) (PPT1D)- and PVDF-PP-TiO2-FeCl3 (PPT2Fe)-modified ultrafiltration membranes, in which TiO2 was modified with DA and FeCl3, forming the cooperation of TiO2/DA and TiO2/Fe3+, with removal rates of 91.4% and 92.6% and quasi-first-order rates of 0.0216 min–1 and 0.0214 min-1. At the same time, the effects of the two types of membrane, UV light and water quality characteristics on the removal performance of the membrane filtration-photocatalytic system were discussed. Among them, the PPT1D membrane was more suitable than the other membranes for the degradation of weakly alkaline water containing SD (pH = 7.5), except when NO3− was present, and the water quality characteristics had a significant inhibitory effect on the removal effect. The PPT2Fe membrane was more suitable for the degradation of acidic water containing SD (pH = 3). Additionally, the water quality characteristics had an obvious inhibitory effect on the removal effect, and the accuracy of the water distribution experimental results was verified by using an actual body of water. In the end, the reaction mechanism of the filtration-photocatalytic system was proposed, and it was found that OH played an indispensable role in the removal of SD.

Microplastics (MPs) are widely distributed in freshwater and have the following characteristics: small size, strong hydrophobicity, difficult degradation, and easy adsorption of toxic substances. These characteristics pose a potential threat to the environment and human health. In this paper, three common MPs in freshwater were removed by conventional dissolved air flotation (DAF) and positive modification DAF (Posi-DAF). The results showed that the optimal removal efficiency of MPs by conventional DAF was 32%-38% at 0.4-0.5 MPa. This indicated that the adhesion between microbubbles (MBs) and MPs was not ideal when the hydrophilic/hydrophobic interaction was the dominant mechanism. However, the removal efficiency of MPs was increased by 13.6%-33.7% compared with that of conventional DAF after two surface modifiers were used on MBs. This result indicated that in addition to the hydrophilic/hydrophobic interaction, both charge attraction and sweeping had positive effects. PRACTITIONER POINTS: The removal efficiency and mechanism of MPs by posi-DAF were investigated. The characteristics, particle number, and adhesion of microplastics were measured. Conventional DAF was dominated by hydrophilic/hydrophobic interactions. CTAB Posi-DAF was dominated by charge attraction. PDADMAC Posi-DAF was dominated by charge attraction and sweeping.

Taking the advantages of reaction-composite brazing and transient liquid phase bonding (TLP), a novel process with the features of low-temperature bonding & high-temperature resisting was implemented to join C-SiC composite and GH4169 superalloy. In the new process, mixed powder of low-melting-point Cu85Ti15 alloy and carbon (C) was used as an interlayer. At a relatively low bonding temperature (990 °C), in-situ reaction of (Cu-Ti)l+Cs→(Cu)s+TiCs and interdiffusion between the (Cu-Ti)l liquid and the GH4169 substrate concurrently occurred to transform the interlayer into a TiC-reinforced (Cu)s matrix composite joining layer. The low-CTE reinforcement TiC helped to alleviate the high residual stress in the joint, and the (Cu)s matrix provided the high-temperature resistance for the joint. In the current work, microstructural behavior, formation mechanism, heat resistance and shear strengths of the bonded joints were investigated. Results indicated that the (Cu-Ti)l/Cs in-situ reaction had an effect of shortening the solidification time of the joining layer, thus decreasing the formation of Ti-C and Ti-Si brittle compounds at the C-SiC side interface. The bonded joints exhibited excellent comprehensive properties: melting temperature of the joining layer reached 1052 °C, which was much higher than that of Cu85Ti15 alloy (898 °C) and the bonding temperature (990 °C); the maximum shear strength at room temperature and 900 °C reached 234 MPa and 101 MPa, respectively.

As the water diversion reservoir showed high organic matter and high algae in summer, the potassium permanganate pre-oxidation/dissolved air flotation/carbon sand double filter process was developed. The test results show that the optimum operation conditions of the combined process were as follows: the dosage of KMnO4 was 0.3 mg/L, the dosage of polymeric aluminum ferric chloride (PAFC) was 3.0 mg/L (Al3+), the reflux ratio was 10%, and the dissolved gas pressure was 0.3 Mpa. Taking Ji'nan Queshan reservoir water algae pollution as the research object, the average removal rate of chlorophyll a, blue-green algae, turbidity, particle number and total organic carbon (TOC) reached 66.64%, 95.44%, 94.45%, 99.34% and 46.68%, respectively; the methylisoborneol (MIB) removal rate was 92.47%, the odor level decreased with process flow from raw water level 4 to effluent level 1.5, geosmin (GSM) dropped below the detection limit, and the total removal rate of trihalomethane formation potential (THMFP) was 33.56%. The effluent of the combined process meets the requirements of the Hygienic Standard for Drinking Water (GB5749-2006) after it is disinfected.

Perfluorinated compounds (PFCs), as emerging persistent pollutants, can exist for a long time in the environment due to their high stability. PFCs have been detected in drinking water, wastewater, and the human body. Studies have shown that PFCs pose a threat to human health and the ecological environment, which is expected to be listed in new drinking water regulations. Traditional processes, including coagulation, biological filtration, chlorination, ozonolysis, and ultraviolet light have ineffective removal efficiency on PFCs; however, advanced oxidation processes (AOP) based on ultraviolet (UV) light have good application prospects for the removal of PFCs. This study provides an overview of the removal of PFCs by UV-based AOPs; systematically introduces the research status of various UV-based AOPs from the perspectives of degradation pathways, degradation efficiency, influencing factors, formation of by-products; and comprehensively compares these different UV-based AOPs. Finally, the limitations of existing research and future research needs are discussed. This review aims to provide an overview for a better understanding of the degradation status and prospects of UV-based AOPs for the degradation of PFCs.

Enoxacin (ENO) is widespread in water because it is commonly used as a human and veterinary antibiotic. However, little effort has been dedicated to revealing the transformation mechanisms of ENO destruction using ClO2, especially within a water distribution system (WDS). To address this knowledge gap, the kinetics, byproducts, toxicity, and formation potential of halogenated disinfection byproducts (DBPs) associated with ENO destruction using ClO2 in a pilot-scale PE pipe was explored for the first time. Statistical analyses showed that the destruction efficiency of ENO in the pilot-scale PE pipe was lower than that in deionized water (DI water), and the reactions in DI water followed the second-order kinetic model. Furthermore, pH has a significant effect on the destruction of ENO, and the removal ratio increased at a higher pH. Additionally, increasing the flow rate elevated the ENO removal efficiency; however, the influence of flow velocity was limited to ENO destruction. The ENO removal rates within the diverse pipes exhibited the following order: stainless steel pipe

Seasonal cyanobacterial blooms in eutrophic water releases algal organic matter (AOM), which contains large amount of dissolved organic nitrogen (DON) and is difficult to be removed effectively by conventional treatment processes (e.g., coagulation and sand filtration) because of its high hydrophilicity. Moreover, N-nitrosodimethylamine (NDMA) can be generated by the reaction of AOM with disinfectants in the subsequent disinfection process. In this study, the formation of NDMA from different AOM components was explored and the control of algal-derived NDMA precursors by UV/H2O2/O3 was evaluated. The results showed that the hydrophilic and polar components of AOM with the low molecular weight had higher NDMA yields. UV-based advanced oxidation process (AOPs) is effective in degrading NDMA precursors, while the removal rate can be affected greatly by UV doses. The removal rate of NDMA precursors by UV/H2O2/O3 is higher than by UV/H2O2 or UV/O3 which can reach 95% at the UV dose of 400 mJ/cm2. An alkaline environment reduces the oxidation efficiency of UV/H2O2/O3 technology, while an acidic environment is conducive to its function. Inorganic anions such as HCO3-, SO42-, Cl- and NO3- are potential to compete with target algal-derived NDMA precursors for the oxidants reaction and inhibit the degradation/removal of these precursors. The degradation of algal-derived NDMA precursors by UV/H2O2/O3 is mainly accomplished by the oxidation of DON with secondary amide groups, and the main degradation mechanism by UV/H2O2/O3 was through the initial decomposition of macromolecular organic compounds such as biopolymers and humic substances and the further degradation of resulting small molecular components.

The quality of raw water and the current high level of pollution presents a phenomenon of high hardness and micropollution. An experimental study was conducted of the nanofiltration (NF) pilot-scale process combined with biological contact oxidation precipitation and ultrafiltration (UF) as the pretreatment process to treat this water. The study investigated the removal efficiency and membrane fouling of the NF process under the continuous and stable operating conditions of the combination process and studied the influence of high-hardness water on the membrane pollution of the combination process. The results showed that the combined process had a positive removal effect on conventional pollutants and characteristic pollutants, and the removal rates of conventional pollutants, such as turbidity, UV254 and CODMn, were 95%, 90% and 85%, respectively. The removal efficiency of total hardness, total alkalinity and soluble total solids reached 98%, 86% and 91%, respectively, and that of total desalination was above 95%. The removal rates of fluorescent organic substances, such as tryptophan, tyrosine, soluble microbial products (SMPs), fulvic acid and humus-like substances, as well as the precursors of disinfection byproducts reached over 88% and 50%, respectively. The pollutant removal efficiency of the combined process was mainly concentrated in the NF unit. The pretreatment process had certain removal effects on turbidity and macromolecular organic substances in the raw water, which provided a perfect operating environment for the NF process. Under long-term operation, the main elements of scaling on the surface of the NF membrane included C, O, Na, Mg, Al, Si, S, Cl, Ca, Ti and Fe, which were mainly concentrated at the outlet of the membrane and mainly came from monomers or compounds composed of inorganic salts in the raw water and some organic compounds. High-hardness water accelerated the change in membrane process parameters, and the surface of the membrane had abundant inorganic scaling. The inorganic scale on the surface of the NF membrane increased noticeably when filtering water with high hardness. Regular cleaning of the UF and NF membranes could effectively restore the parameters of the process and prolong the service life of the membrane process.

Water from the Yellow River reservoir is treated by dissolved air flotation (DAF), but the flocs formed are loose and easily desorbed. To solve this problem, a new air flotation process, i.e., Posi-co-coagulation dissolved air flotation (Posi-CCDAF), was developed by combining DAF with microbubble surface modification technology. The feasibility of the Posi-CCDAF process was verified by using chitosan to modify the surfaces of the microbubbles. The optimal dosage ratio of chitosan/coagulant was 0.4, and the optimal pH of the reflux water was 6.00. The removal characteristics of organic pollutants under the optimal conditions were studied. The removal characteristics of natural organic matter (NOM) with different molecular weights before and after adding chitosan were compared, and the removal efficiency of disinfection byproduct precursors was evaluated. Microscopic analysis was used to observe the bubble floc adhesion process and flocs during the copolymerization process before and after the addition of chitosan. The results showed that chitosan promoted the removal of hydrophobic macromolecular organics and the trihalomethane formation potential (THMFP) by CCDAF. On the one hand, the surface of modified microbubbles in Posi-CCDAF was positively charged, which provided electrostatic force to enhance the adhesion of flocs during polymerization; on the other hand, the combination of chitosan and macromolecular organics in water formed a capture network, which made the bubble flocs larger and caused them to adhere tightly, improving the removal effect of air flotation.

With the aim of alleviating the residual thermal stress in the C/C-GH3044 joints, a novel composite brazing, which combines Ag-Ti reactive composite brazing and TiC particle-reinforced composite brazing, was adopted for joining C/C composite to Ni-based superalloy GH3044 using (Ag-10Ti)+TiC composite filler material. The results showed that the composite interlayer was strengthened by four kinds of reinforcements, containing the introduced TiC, the in situ synthesized AgTi and Ti2Ni phases, and the residual Ti particles. With increasing TiC content from 0 to 32 %, the thermal expansion coefficient of the composite interlayer declined by 18.2 %, which is helpful in alleviating the residual thermal stress in the joints. In addition, the introduced TiC particles decreased the fluidity of the filler material and inhibited the inter-diffusion of atoms between GH3044 and filler material. As a result, the continuous brittle compound Ti2Ni in the composite interlayer was effectively reduced, so the composite interlayer had good plasticity. Meanwhile, the thickness of the composite interlayer gradually increased from 260 μm to 520 μm, and the finite element analysis showed that the corresponding peak value of von Mises stress decreasedby 20.1 %. The highest shear strength of the joints was 67.2 MPa obtained with (Ag-10Ti)+24 %TiC at 1020°C for 30 min,which is almost the same strength as the C/C composite matrix used in this study.

In the traditional dissolved air flotation (DAF), micro bubbles generally cannot mesh and adhere to particles efficiently, and the adhesion between microbubbles and particles is not stable, either. In this paper, a self-developed copolymerization dissolved air flotation (Co-DAF) system was proposed to strengthen the copolymerization of condensation reaction during the adhesion of bubbles and flocs, by grading the refluxed dissolved air water, which could significantly enhance the adhesion efficiency and the stability of the bubble-flocs. On this basis, raw water of low turbidity, high algae and high organic contents from the Yellow River reservoir was used as the water supply to verify the effectiveness of the proposed system. The results showed that the average removal rate of turbidity was 95.2%, among, which 93.6% of the particles larger than 2 μm were removed effectively. Meanwhile, the removal rates of CODMn, UV254, DOC, SUVA and ammonia nitrogen were 43.2%, 48.5%, 38.2%, 20.5 and 77.3%, respectively, and those of organics with molecular weight between 3000–10000 Da and more than 3000 Da were 30.6% and 85%, respectively. However, for those organics with molecular weight less than 1000 Da, only a removal rate of 10% was achieved. During the test, DBPFP could be well controlled by the Co-DAF process, and the removal rates of CHCl 3, CHClBr2, CHCl 2Br and CHBr3 were 22.9%, 21.9%, 16.0% and 18.2%, respectively. It was deduced that the mechanisms of removing pollutants by the Co-DAF process mainly included the collision and adhesion effects between micro bubbles-floc particles, the copolymerization between microbubble-flocs and particles, and the adsorption bridging effects among bubble-flocs, microbubbles and particles.

The problem of reservoir water quality caused by massive algae pollution keeps going serious, and the traditional solid-liquid separation technology generally fails to meet water quality standards. In the present study, GAC-sand-double-filtration flofilter was built to treat reservoir water derived from the Yellow River that has been polluted by high levels of algal biomass, with the running characteristics and operating results specifically investigated. The experimental results showed that, running effect was relatively superior when the dosage of PAFC was 4 mg/L (Al3+), the pressure of dissolved air was 0.4 Mpa, and the reflux ratio was 8%. Algal biomass fixed onto GAC and sand filter layer was mainly found in the carbon layer, which accounted for 97.4% of the total biomass (the highest value was 50.2 nmol p/g), and the biomass fixed onto carbon layer was 16.7 times of that fixed onto the sand layer (3.0 nmol p/g). Clearly, the removal of pollutants mainly occurred in the carbon layer. Also, the removal efficiency of particulate matter such as blue-green algae, turbidity, CODMn, UV254, NPOC, ammonia nitrogen was 96.48%, 92.40%, 92.56%, 57.40%, 52.50%, 51.60% and 75.67%, respectively. The odor was reduced from 4 to 0, and the content of geosmin and methylisoborneol was less than their detection limit, with the removal efficiency of chloroform and chlorodibromomethane as 60% and 55.1%, respectively. In general, the results showed that the flofilter process had imposed an efficient effect on the removal of algal biomass, odor substances and disinfection byproducts precursors.

A novel joining process named reactive composite-diffusion brazing was developed to join carbon fiber reinforced SiC ceramic matrix composite (Cf/SiC) and nickel-plated stainless steel using a powder-filler of Cu–15Ti alloy and carbon (C). Based on reaction (Cu–Ti)+C + Ni→TiC+(Cu,Ni)ss, the C particles reacted with Ti element in Cu–15Ti alloy with low melting temperature formed reinforcement TiC, which improved the joint heat resistance; the Ni atoms in the nickel plating diffused into the joining layer, further improving the joint heat resistance. The initial melting temperature of the joint raised to 1025 °C, which is 130 °C higher than that of Cu–15Ti alloy.

In this paper, water from the Yellow River reservoir was treated with Polyaluminum chloride (PAC) and a PAC/chitosan (CTS) composite to study the flocculation efficiency, changes in the flocculation characteristics, and the role played by CTS in the process of coagulation. The floc microstructure was analyzed by scanning electron microscopy, and the floc characteristics and fractal dimension were studied using a laser particle size analyzer. The results showed that addition of a small quantity of CTS could produce a relatively good coagulation effect, and the removal effect of each index increased by 8.7 %–46.83 % compared with that obtained with only PAC. However, as the dose increased, the effects on various indexes did not increase significantly. Under the same conditions, the growth rate and size of flocs formed with the composite coagulant containing CTS were better than those obtained with only PAC, with an increase in the floc size about 36.67 % with CTS. The floc regeneration capacity showed the opposite trend. It is likely that when long-chain bridging is dominant, the conditions are more conducive to rapid formation of structured and dense flocs. By contrast, when electrical neutralization plays a leading role, the flocs have better disintegration and regeneration abilities.

The technique of coupling photocatalysis and membrane filtration was applied to the abatement of sulfonamide antibiotics in water. TiO2 photocatalyst has been aroused widespread concern in recent years due to its low price and easy availability. A PVDF-PVP-TiO2-Dopamine blend ultrafiltration membrane (PPTD) was first fabricated in this study and removal of sulfadiazine (SD) in water using a PPTD membrane filtration-photocatalysis system was realized. The addition of PVP-TiO2-Dopamine increased the porosity and average pore size of membranes, resulting in improved hydrophilicity, flux of modified membranes. In pure water, the SD removal efficiency was 91.4% with a first-order rate constant k 0.0216 min−1 under the optimum conditions ([SD]0 = 0.4 µmol/L, UV = 125 µW/cm2, pH = 7.5 ± 0.1, t = 2 h). Water quality parameters (NO3−, Cl−, SO42−, humic acid (HA)) showed quite different effects on SD decontamination. Simulated degradation experiments using real samples demonstrated that PPTD membrane filtration-photocatalysis system has significant potential with regard to controlling SD as pollutants in water. The photocatalytic mechanism characterized using ESR indicated that OH was largely responsible for SD decontamination. The mechanism of the PPTD membrane filtration-photocatalysis system suggests that TiO2-Dopamine could exist synergistically through the bidentate structure or the chelated structure, and that OH, O2−, HO2 , H2O2 and 1O2 may be produced in the PPTD membrane filtration-photocatalysis system.

Biofilm is an effective simultaneous denitrification and in situ sludge reduction system, and the characteristics of different biofilm carrier have important implications for biofilm growth and in situ sludge reduction. In this study, the performance and mechanism of in situ sludge reduction were compared between FSC-SBBR and SC-SBBR with constructed by composite floating spherical carriers (FSC) and multi-faceted polyethylene suspension carriers (SC), respectively. The variation of EPS concentration indicated that the biofilm formation of FSC was faster than SC. Compared with SCSBBR, the FSC-SBBR yielded 0.16 g MLSS/g COD, almost 27.27% less sludge. The average removal rates of COD and NH4+-N were 93.39% and 96.66%, respectively, which were 5.21% and 1.43% higher than the average removal rate of SC-SBBR. Investigation of the mechanisms of sludge reduction revealed that, energy uncoupling metabolism and sludge decay were the main factors for sludge reduction inducing 43.13% and 49.65% less sludge, respectively, in FSC-SBBR. EEM fluorescence spectroscopy and SUVA analysis showed that the hydrolytic capacity of biofilm attached in FSC was stronger than those of SC, and the hydrolysis of EPS released more DOM contributed to lysis-cryptic growth metabolism. In additional, Bacteroidetes and Mizugakiibacter associated with sludge reduction were the dominant phylum and genus in FCS-SBBR. Thus, the effect of simultaneous in situ sludge reduction and pollutant removal in FSC-SBBR was better.

Countercurrent–cocurrent dissolved air flotation (CCDAF), the popular water purification device, which consists of collision and adhesion contact zones, showed favorable flotation conditions for micro-bubble adhesion and stability. In this study, computational fluid dynamics (CFD) numerical simulation was employed to confirm that the unique CCDAF configuration create reasonable and that the flow field characteristics were good no matter for single phase or gas–liquid two-phase conditions. In addition, the turbulence of the flow field was enhanced with the increasing influent load; the swirling was remarkably reduced with the increase of gas holdup. Meanwhile, a thick micro-bubble filter layer was formed in the separation zone, which favored bubble-flocs agglomerating and rising. The force analysis also showed that the cross section within the tank contribute to the uniformity of the bottom water collection as well as enlargement of the bottom outflow area, therefore improving the overall flotation performance. The simulation results revealed for the CCDAF process can provide technical guidance for engineering design and application.

Currency shocks affect future corporate earnings: companies exporting in countries with an appreciating currency see their earnings increase. Using company-level data on geographic sales, we document that analysts fail to fully integrate currency shocks into their firm-level forecasts: their forecast errors can therefore be predicted by past currency movements. We also show that stock prices do not respond immediately to currency shocks: prices take about two weeks to integrate them. This is true for small to medium size shocks but not for larger shocks, in line with a bounded rationality interpretation. Finally, we find some evidence that arbitrage capital exploiting this anomaly has increased in recent years.

Anaerobic ammonium oxidation (anammox) immobilized particles were added to a reactor as biocatalyst to start an up-flow anammox reactor. The kinetic characteristics of the immobilized particles were studied using batch tests. The results demonstrated that using immobilized particles as the biocatalyst succeeded in starting the anammox reactor in 49 d. The removal rates of -N and -N were 80.7 and 83.1%, respectively. The total nitrogen removal load was 0.505 kg m−3 d−1. The results of the kinetic characteristics study demonstrated that the half-saturation constants of the immobilized particles for ammonium and nitrite were 1.57 and 1.505 mmol L−1, respectively. These constants were lower than those of flocculent anammox sludge (FAS), which indicated that the immobilized particles utilize the substrate better in adverse environments. The half-suppression constants of the immobilized particles for ammonia and nitrite were 724.2 and 66.65 mmol L−1, respectively, and higher than those of FAS. Thus, the...

Municipal wastewater treatment suffers the general problems of poor denitrification and low phosphorus removal caused by insufficient carbon sources. Thus, a baffled reactor was developed to provide additional carbon by hydrolysis and acidification of the primary sludge in the A2/O process in order to treat low C/N ratio wastewater. The effects on denitrification and phosphorus removal were evaluated. The results showed that CTN, CTP, CCOD, and -N in the effluent were concentrated at 17, 0.5, 30, and 1.6 mg/L, respectively, while the removal efficiencies rose to 69.6, 92.5, 88, and 96.7%, respectively, while dosing acidified primary sedimentation sludge. Compared with control groups that did not receive acidification liquid, CTN, CTP, and -N of the effluent were decreased by 8.7, 1.3, and 0.7 mg/L, respectively, and the removal efficiencies were correspondingly increased by 15.6, 22.5, and 1.7%, respectively. These data demonstrated that adding acidified primary sludge effectively improved the rem...

High thermal-expansion mismatched C-SiC composite and 304 stainless steel have been bonded by a 72Ag + 18Ti + 10Mo (at%) mixed powder filler. At the bonding temperature (1020 °C), the filler was in semi-solid state, i.e. solid-liquid mixed state of Mo particles, TiAg grains and Ag(Ti) liquid. Microstructural analysis indicated that the high activity and viscosity of the semi-solid filler help to obtain a large-thickness homogeneous joining layer (∼416 mm), in which Mo particles were clad by (Ti,Mo) solid solution and uniformly dispersed in Ag matrix together with the TiAg grains. The large thickness joining layer mainly composed of low coefficient of thermal expansion (CTE) Mo particles and ductile Ag matrix can effectively reduce the high residual stresses of the joint caused by the thermal-expansion mismatch between the dissimilar materials. Additionally, interfaces between the base materials and the joining layer were well bonded without continuous layered brittle compounds. The interfacial reaction products at C-SiC side were TiC, Ti5Si3 and Ti3SiC2 grains in Ag matrix. At 304 interface, Ti2Ni + Ti(Fe,Ni) compounds grew in columnar and gathered nearby. The characteristics of the joining layer and the bonding interfaces contribute to the high joint strength. The average shear strength of the joint at room temperature was 156 MPa.

The microstructure and formation mechanism of the Cf/SiC composite and stainless steel joints brazed with Ag+Ti filler were investigated. The effects of Ti content (10%˜40%, at %), bonding temperature (990˜1080 °C) and holding time (15˜60 min) on microstructure and mechanical properties of the joints were discussed. The results indicated that a large-thickness interlayer was formed after bonding, in which in-situ formed TiAg particulates and residual Ti particles were dispersed in Ag matrix. Compared with the common composite interlayers, the interlayer formed via Ag+Ti in-situ alloying had more and finer reinforcing phases without reducing the activity of the filler material. The ductile Ag matrix contributed to accommodate the large strain mismatch by elastic deformation. The interfaces between the adjoining materials and the interlayer were well-bonded without any cracks. At Cf/SiC side interface, TiC, Ti5Si3 and Ti3SiC2 grains were generated from SiC matrix and carbon fibers were exposed. A meshing interface was formed, which was beneficial to arrest and deflect cracks and improve the shear strength of the joints. Kirkendall voids were observed at 304 side interface. Especially they were formed in the joints prepared using high Ti content filler materials (Ag+30%˜40%Ti, at %) or bonded at relatively low joining temperature (990 °C). When the content of Ti was fixed, the joint shear strength increased firstly and then decreased with the bonding temperature. Different Ti contents corresponded to different peak bonding temperatures. The holding time had a similar effect on the joint strength as bonding temperature. The maximum joint shear strength at room temperature was 141 MPa obtained at 1020 °C for 30 min with Ag+30 at %Ti composite filler.

The designed capacity of Jinan Citys wastewater treatment plant (the second sewage treatment plant) is 200,000 m3/d, and the biological treatment process is DE-type oxidation ditch process. Because of self-control requirements, equipment quality and management , alternat-ing operation of anoxia and oxygen can not be achieved. Acting in concert with the engineering of south-to-north water diversion and water quality improvement of the Xiaoqing River, water quality improvement and transformation of nitrogen and phosphorus removal process was condu-cted. By increasing the diversion wall, digestive reflux and other measures, the DE oxidat-ion ditch process was transformed into A2/O process, while the depth of V-efficiency fiber filter processing and chemical phosphorus removal process were increased. After the upgrade, the process is stable, the effluent quality reached an A standard of " discharge standard of pollutants for municipal wastewater treatment plant" (GB18918-2002).