Yb(OTf)3 catalyzed [1,3]-rearrangement of 3-alkenyl oxindoles.

A Yb(OTf)3 catalyzed [1,3]-rearrangement of 3-alkenyl oxindoles was achieved, affording a variety of multifunctional 3-ylideneoxindoles with good yields and Z/E selectivities (64%-89% yield, 78 : 22->99 : 1 Z/E). Importantly, an operationally simple, one-pot sequential catalytic synthesis of 3-ylideneoxindoles was also developed. Additionally, a cross [1,3]-rearrangement experiment and nonracemic transformation were also carried out, which indicated a concerted rearrangement mechanism of this methodology.

Multi-phase distribution and comprehensive ecological risk assessment of heavy metal pollutants in a river affected by acid mine drainage.

To date, there is a lack of a comprehensive research on heavy metals detection and ecological risk assessment in river water, sediments, pore water (PW) and suspended solids (SS). Here, the concentrations of heavy metals, including Cu, Zn, Mn, Cd, Pb and As, and their distribution between the four phases was studied. Samples for analysis were taken from twelve sites of the Hengshi River, Guangdong Province, China, during the rainy and dry seasons. A new comprehensive ecological risk index (CERI) based on considering metal contents, pollution indices, toxicity coefficients and water categories is offered for prediction of potential risk on aquatic organisms. The results of comprehensive analysis showed that the highest concentrations of Cu, Zn and Mn of 6.42, 87.17 and 98.74mg/L, respectively, in PW were comparable with those in water, while concentrations of Cd, Pb and As of 609.5, 2757 and 96.38µg/L, respectively, were 2-5 times higher. The sum of the exchangeable and carbonate fractions of target metals in sediments followed the order of Cd > Mn > Zn > Pb > Cu > As. The distribution of heavy metals in phases followed the order of sediment > SS > water > PW, having the sum content in water and PW lower than 2% of total. The elevated ecological risk for a single metal and the phase were 34,585 for Cd and 1160 for water, respectively, implied Cd as a priority pollutant in the considered area. According to the CERI, the maximum risk value of 769.3 was smaller than 1160 in water, but higher than those in other phases. Out of considering the water categories and contribution coefficients, the CERI was proved to be more reliable for assessing the pollution of rivers with heavy metals. These results imply that the CERI has a potential of adequate assessment of multi-phase composite metals pollution.

The occurrence and fate of phenolic compounds in a coking wastewater treatment plant.

The occurrence of 14 phenolic compounds (PCs) was assessed in the raw, treated wastewater, dewatered sludge and gas samples from a coking wastewater treatment plant (WWTP) in China. It was found that 3-cresol was the dominant compound in the raw coking wastewater with a concentration of 183 mg L(-1), and that chlorophenols and nitrophenols were in the level of µg L(-1). Phenol was the dominant compound in the gas samples, while 2,4,6-trichlorophenol predominated in the dewatered sludge sample. The anaerobic and aerobic tanks played key roles in the elimination of chlorophenols and phenols, respectively. Analysis of daily mass flows of PCs in WWTP showed that 89-98% of phenols and 83-89% of nitrophenols were biodegraded, and that 44-69% of chlorophenols were adsorbed to sludge, indicating that the fate of PCs was highly influenced by their biodegradability and physical-chemical property.

Switchable multipath cascade cyclization to synthesize bicyclic lactams and succinimides via chemodivergent reaction.

Herein, a novel switchable multipath cascade cyclization via chemodivergent reaction between readily available ketoamides and deconjugated butenolides was developed to efficiently synthesize γ-lactone fused γ-lactams and succinimide fused hemiketals. The Aldol/aza-Michael reaction and Aldol/imidation/hemiketalization reaction were enabled by catalytic amounts of two bases, namely tetramethyl guanidine and NaOAc. A wide range of substrate scope with diverse functional group compatibility was demonstrated to deliver the corresponding products with good yield and excellent diastereoselectivity (>60 examples).

Identification and characterization of polycyclic aromatic hydrocarbons in coking wastewater sludge.

GC-MS analysis was performed on the coking sludge from a coking wastewater treatment plant (WWTP) to allow detailed chemical characterization of polycyclic aromatic hydrocarbons (PAHs). The identification and characterization of the isomers of PAHs was based on a positive match of mass spectral data of their isomers with mass spectra databases or based on a comparison of electron impact ionization mass spectra and retention times of target compounds with those reference compounds. In total, 160 PAH compounds including numerous N-, O-, S-, OH-, and Cl-containing derivatives were positively identified for the first time. Quantitative analysis of target compounds was performed in the selected ion-monitoring mode using the internal standard method. The total concentrations of selected compounds in the coking sludge samples from the anaerobic tank, aerobic tank, hydrolytic tank, and secondary clarifier of the WWTP ranged from 1690 ± 585 to 6690 ± 522 mg/kg, which were much higher than those in other industrial and municipal sludges. PAHs with four and five rings were found to be the dominant compounds, and diagnostic ratios of these compounds suggested that they had the characteristics of coal combustion and pyrolysis.

Treatment of food processing wastewater in a full-scale jet biogas internal loop anaerobic fluidized bed reactor.

A full-scale jet biogas internal loop anaerobic fluidized bed (JBILAFB) reactor, which requires low energy input and allows enhanced mass transfer, was constructed for the treatment of food processing wastewater. This reactor has an active volume of 798 m(3) and can treat 33.3 m(3) wastewater per hour. After pre-treating the raw wastewater by settling, oil separating and coagulation-air floating processes, the reactor was operated with a relatively shorter start-up time (55 days). Samples for the influent and effluent of the JBILAFB reactor were taken and analyzed daily for the whole process including both the start-up and stable running periods. When the volumetric COD loading fluctuated in the range of 1.6-5.6 kg COD m(-3) day(-1), the COD removal efficiency, the volatile fatty acid(VFA)/alkalinity ratio, the maximum biogas production and the content of CH(4) in total biogas of the reactor were found to be 80.1 ± 5%, 0.2-0.5, 348.5 m(3 )day(-1) and 94.5 ± 2.5%, respectively. Furthermore, the scanning electron microscope (SEM) results showed that anaerobic granular sludge and microorganism particles with biofilm coexisted in the reactor, and that the bacteria mainly in bacilli and cocci were observed as predominant species. All the data demonstrated that the enhanced mass transfer for gas, liquid and solid phases was achieved, and that the formation of microorganism granules and the removal of inhibitors increased the stability of the system.

Dechlorination of chlorobenzene in subcritical water with Fe/ZrO2, Ni/ZrO2 and Cu/ZrO2.

To obtain information about dechlorination of organochlorine compounds in subcritical water catalyzed by metals assisted with ZrO(2), dechlorination of chlorobenzene has been investigated in the presence of Fe/ZrO(2), Ni/ZrO(2) and Cu/ZrO(2) catalysts. The dechlorination efficiency was increased with increasing residence time, temperature and pressure. The order of effectiveness of the catalysts was Cu/ZrO(2) < Ni/ZrO(2) < Fe/ZrO(2). The dechlorination of chlorobenze obeyed pseudo-first-order kinetics models. The rate constants in subcritical water were much greater than that in ambient-temperature water; the activation energies were obtained. ZrO(2) in the catalyst had the power to absorb chlorobenzene onto the catalyst surface and promoted the dechlorination ability of the metal. The primary mechanism for dechlorinaton of chlorobenzene involved the reduction of chlorobenzene by reaction with nascent hydrogen. The nascent hydrogen reacted with the chlorobenzene, which adsorbed on the catalyst in non-planar and co-planar form, and formed benzene and chloride ions.

Material inter-recycling for advanced nitrogen and residual COD removal from bio-treated coking wastewater through autotrophic denitrification.

For wastewaters containing high strength sulfide and nitrogen (e.g. coking wastewater), sulfide might be precipitated and recovered using ferrous salt. This study systematically investigated the feasibility of recovered and precipitated FeS (comparing to commercial FeS minerals) to support autotrophic denitrification for advance nitrogen removal from bio-treated coking wastewater in fluidized bed reactors. The reactor with precipitated FeS could achieve simultaneous removal of NO3--N and inert COD with high efficiencies of around 96.3% and 30.5%, at NO3--N and COD loading rates of 4.18 mg·L-1·h-1 and 8.06 mg·L-1·h-1, respectively. Whereas, the performance of commercial FeS reduced gradually and irreversibly after two days, which became completely ineffective after 40 days. Thiobacillus and Rhodanobacter dominated the biomass, which played a key role in the FeS-based denitrification process. This material inter-recycling concept benefits an advance and more sustainable treatment of wastewaters with high strength sulfide and nitrogen.

Structure and function of microbial community involved in a novel full-scale prefix oxic coking wastewater treatment O/H/O system.

A novel full-scale prefix oxic coking wastewater (CWW) biological treatment O/H/O system had been operated steadily six years with the effluent quality meeting national discharge standard. Comparing to the traditional CWW biological treatment process, which usually have an anaerobic unit at the start of the process, here the O/H/O system has obvious advantages in COD removal, total nitrogen removal and reduced energy consumption. It is very necessary to illustrate the structure and function of the microbial community involved in different bioreactors of the O/H/O system. High-throughput MiSeq sequencing was used to examine the 16S rRNA genes in this system. Results revealed a contrasting microbial composition among the activated sludge samples of three sequential bioreactors: the ß-Proteobacteria related sequences dominated in the O1 activated sludge with the relative abundance of 56.44% while 7.53% of the sequences were assigned to Thiobacillus; Rhodoplanes related sequences dominated in the bioreactor H and O2 activated sludge with relative abundance of 8.86% and 8.92%, respectively. The physico-chemical characteristics of CWW were analyzed by standard methods and the operational parameters were routinely monitored to examine their effects on the microbial communities. The bioinformatics software package of phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) was used to predict the microbial community functional profiling and found three dominant genera of Rhodoplanes, Lysobacter and Leucobacter enriched the xenobiotics biodegradation and metabolism pathway. The diverse and distinct microbial community involved in biological treatment processes of CWW treatment indicating that water characteristics and operational parameters determined the microbial community composition. These results significantly expanded our knowledge of the biodiversity and population dynamics of microorganisms and discerned the relationships between bacterial communities and environmental variables in the biological treatment processes. Moreover, in this study, we proposed a comprehensive biodegradation model of CWW treatment and defined as O/H/O system.

Chiral 1H NMR of Atropisomeric Quinazolinones With Enantiopure Phosphoric Acids.

A chiral phosphoric acid promoted enantioselective NMR analysis of atropisomeric quinazolinones was described, in which a variety of racemic arylquinazolinones such as afloqualone and IC-87114 were well recognized with up to 0. 21 ppm ΔΔδ value. With this method, the optical purities of different non-racemic substrates can be fast evaluated with high accuracy.

[Behavior and Degradation of Polycyclic Aromatic Hydrocarbons (PAHs) in Coking Wastewater of A/O2 and A/O/H/O Processes].

Polycyclic aromatic hydrocarbons (PAHs) are typical organic pollutants found in coking wastewater, and their behavior and reduction can be affected by different treatment processes. Based on these considerations, this study investigated the behaviors of PAHs in coking wastewater under A/O2 and A/O/H/O treatment processes, respectively. In order to evaluate variations in PAH removal under two different treatment processes, samples were taken from different treatment units for quantification of PAHs using gas chromatography-mass spectrometry. Results showed that PAHs were barely degraded in anaerobic tanks of either treatment process and accumulated much higher concentrations than in aerobic and hydrolytic tanks. While low molecular weight PAHs (LMW PAHs) in aqueous phase from anaerobic tanks were degraded effectively in aerobic tanks, high molecular weight PAHs (HMW PAHs) mostly accumulated in the sludge phase; these potentially pose a higher environmental risk and therefore need to be treated separately. Moreover, the A/O/H/O process showed higher degradation of PAHs bioavailability and higher removal effectiveness for PAHs with four or more benzene rings than the A/O2 process; this is attributed to the hydrolytic tank's ability to promote hydrolysis of macromolecular organic compounds and therefore improve biodegradability of PAHs. Comprehensive results from the study indicated that the A/O/H/O process is more advantageous for degradation of PAHs than the A/O2 process.

Characteristics of high-sulfate wastewater treatment by two-phase anaerobic digestion process with Jet-loop anaerobic fluidized bed.

A new anaerobic reactor, Jet-loop anaerobic fluidized bed (JLAFB), was designed for treating high-sulfate wastewater. The treatment characteristics, including the effect of influent COD/SO4(2-) ratio and alkalinity and sulfide inhibition in reactors, were discussed for a JLAFB and a general anaerobic fluidized bed (AFB) reactor used as sulfate-reducing phase and methane-producing phase, respectively, in two-phase anaerobic digestion process. The formation of granules in the two reactors was also examined. The results indicated that COD and sulfate removal had different demand of influent COD/SO4(2-) ratios. When total COD removal was up to 85%, the ratio was only required up to 1.2, whereas, total sulfate removal up to 95% required it exceeding 3.0. The alkalinity in the two reactors increased linearly with the growth of influent alkalinity. Moreover, the change of influent alkalinity had no significant effect on pH and volatile fatty acids (VFA) in the two reactors. Influent alkalinity kept at 400-500 mg/L could meet the requirement of the treating process. The JLAFB reactor had great advantage in avoiding sulfide and free-H2S accumulation and toxicity inhibition on microorganisms. When sulfate loading rate was up to 8.1 kg/(m3 x d), the sulfide and free-H2S concentrations in JLAFB reactor were 58.6 and 49.7 mg/L, respectively. Furthermore, the granules, with offwhite color, ellipse shape and diameters of 1.0-3.0 mm, could be developed in JLAFB reactor. In granules, different groups of bacteria were distributed in different layers, and some inorganic metal compounds such as Fe, Ca, Mg etc. were found.

Supercritical gasification for the treatment of o-cresol wastewater.

The supercritical water gasification of phenolic wastewater without oxidant was performed to degrade pollutants and produce hydrogen-enriched gases. The simulated o-cresol wastewater was gasified at 440-650 degrees C and 27.6 MPa in a continuous Inconel 625 reactor with the residence time of 0.42-1.25 min. The influence of the reaction temperature, residence time, pressure, catalyst, oxidant and the pollutant concentration on the gasification efficiency was investigated. Higher temperature and longer residence time enhanced the o-cresol gasification. The TOC removal rate and hydrogen gasification rate were 90.6% and 194.6%, respectively, at the temperature of 650 degrees C and the residence time of 0.83 min. The product gas was mainly composed of H2, CO2, CH4 and CO, among which the total molar percentage of H2 and CH4 was higher than 50%. The gasification efficiency decreased with the pollutant concentration increasing. Both the catalyst and oxidant could accelerate the hydrocarbon gasification at a lower reaction temperature, in which the catalyst promoted H2 production and the oxidant enhanced CO2 generation. The intermediates of liquid effluents were analyzed and phenol was found to be the main composition. The results indicate that the supercritical gasification is a promising way for the treatment of hazardous organic wastewater.

Identification and removal of polycyclic aromatic hydrocarbons in wastewater treatment processes from coke production plants.

Identification and removal of polycyclic aromatic hydrocarbons (PAHs) were investigated at two coke plants located in Shaoguan, Guangdong Province of China. Samples of raw coking wastewaters and wastewaters from subunits of a coke production plant were analyzed using gas chromatography-mass spectrometry (GC/MS) to provide a detailed chemical characterization of PAHs. The identification and characterization of PAH isomers was based on a positive match of mass spectral data of sample peaks with those for PAH isomers in mass spectra databases with electron impact ionization mass spectra and retention times of internal reference compounds. In total, 270 PAH compounds including numerous nitrogen, oxygen, and sulfur heteroatomic derivatives were positively identified for the first time. Quantitative analysis of target PAHs revealed that total PAH concentrations in coking wastewaters were in the range of 98.5 ± 8.9 to 216 ± 20.2 µg/L, with 3-4-ring PAHs as dominant compounds. Calculation of daily PAH output from four plant subunits indicated that PAHs in the coking wastewater came mainly from ammonia stripping wastewater. Coking wastewater treatment processes played an important role in removing PAHs in coking wastewater, successfully removing 92 % of the target compounds. However, 69 weakly polar compounds, including PAH isomers, were still discharged in the final effluent, producing 8.8 ± 2.7 to 31.9 ± 6.8 g/day of PAHs with potential toxicity to environmental waters. The study of coking wastewater herein proposed can be used to better predict improvement of coke production facilities and treatment conditions according to the identification and removal of PAHs in the coke plant as well as to assess risks associated with continuous discharge of these contaminants to receiving waters.

[Analysis of novel style biological fluidized bed A/O combined process in dyeing wastewater treatment].

A novel biological fluidized bed was designed and developed to deal with high-concentration refractory organic industrial wastewater. From 12 successful projects, three cases of dyeing wastewater treatment projects with the scale of 1200, 2000 and 13000 m3/d respectively were selected to analyze the principle of treating refractory organic wastewater with fluidized bed technology and discuss the superiority of self-developed biological fluidized bed from the aspects of technical and economic feasibility. In the three cases, when the hydraulic retention time (HRT) of biological system were 23, 34 and 21. 8 h, and the volume loading of influents (COD) were 1.75, 4.75 and 2.97 kg/(m3 x d), the corresponding COD removal were 97.3%, 98.1% and 95.8%. Furthermore the operating costs of projects were 0.91, 1.17 and 0.88 yuan per ton of water respectively. The index of effluent all met the 1st grade of Guangdong Province wastewater discharge standard. Results showed that the biological fluidized bed had characteristics of shorter retention time, greater oxygen utilization rate, faster conversion rate of organic pollutants and less sludge production, which made it overcome the shortcomings of traditional methods in printing and dyeing wastewater treatment. Considering the development of technology and the combination of ecological security and recycling resources, a low-carbon wastewater treatment process was proposed.

[Adsorption process of organic contaminant in untreated coking wastewater by powdered activated carbon].

The article investigated the removal of organic contaminant from coking wastewater in adsorption process using powdered activated carbon as adsorbent. The dose of activated carbon, temperature, pH and reaction time were studied, and UV-Vis and GC/MS were used to carry out the qualitative and semiquantitative analysis of organic compositions in wastewater. The results showed that the optimum conditions for pretreatment of coking wastewater were 6 g activated carbon per liter, 30 degrees C, pH = 9 and reaction for 20 min, under which the removal efficiency of organic pollutants are more than 70%. Among the 56 kinds of organic compounds, 45 kinds such as dolichoalkanes, polynucleation aromatic series, azacyclo compounds could be removed, and the removal ratios of amidobenzene, hydroxybenzene, indoleacetic, acid-2-methyl-phenyl-ester are 63.5%, 42.6%, 88.1%, 28.1% respectively, while cresol and xylenol are more than 70% and 85%. In the adsorption process of multi-composition system in wastewater, macromolecules with low-pole and major -delta G0 as polynuclear aromatic hydrocarbons and azacyclo compounds could be adsorbed preferentially and completely in tacho-absorption period, while micromolecule with hadro-pole and inferior -delta G0 as amidobenzene and hydroxybenzene were adsorbed ambly.

[Oxidation treatment of formaldehyde-containing wastewater by electro-Fenton method].

The mechanisms of affecting factors in treating formaldehyde-containing organic wastewater by electro-Fenton reactor which had granular carbon as the filled electrode were investigated. The optimal operating conditions determined by orthogonal experiments and individual factor experiments were as following: 90 min, 25 V, 30 degrees C-40 degrees C, insulating carbon content 40%, Fe2+ concentration 300 mg/L at pH < 3.5. Formaldehyde degradation mechanisms were proposed after analyzing the oxidation products with UV absorbance spectrum. Experiment of treating the actual wastewater using this method were also performed. The removal rates of formaldehyde and CODCr were about 90%, 30%, respectively. In addition, the operating cost was 42.3% less than that of treatment by Fenton method.