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1.
Anaerobic-anoxic-aerobic sequential degradation of synthetic wastewaters   总被引:2,自引:0,他引:2  
This study was conducted in a continuous three-stage system of anaerobic (R1)-anoxic(R2)-aerobic (R3) reactors with synthetic wastewater containing phenol (1000 mg/L), chemical oxygen demand (COD) (3000 mg/L), CN (30 mg/L), SCN(400 mg/L), and NH 4 + -N (600 mg/L) as principal pollutants and well-acclimated heterogeneous microbial cultures. The final effluent was partially returned to R2 with a recycle ratio of 1. Anaerobic stage served to detoxify the feed by removing up to 80% of cyanide. Complete SCN removal and denitrification could be achieved in the anoxic stage by utilizing phenol as an internal source of carbon. Nitrification efficiency of 93% was obtained in the aerobic reactor. The results demonstrated that the three-stage system can give the desired final treated effluent quality (0 mg/L of phenol, 0.2 mg/L of CN, 210 mg/L of COD, and 20 mg/L of NH 4 + -N) and that the NO 3 -N concentration can be lowered by a higher recycle ratio.  相似文献   

2.
The extraction of the pertechnetate anion has been investigated in the systems tributylphosphate (TBP)—solvent (carbon tetrachloride, n-heptane, chloroform)—metal salt (uranyl nitrate and chloride, thorium nitrate)—ammonium salt. In the absence of a metal, the solvates HTeO4. iTBP (i=4) are extracted, while in the presence of uranium and thorium, the distribution of technetium corresponds to the formation of the mixed complexes: UO2(NO3)(TeO4)·2TBP, UO2Cl(TcO4)·2TBP and Th(NO3)3 (TcO1)·2TBP. The effective constants of the reactions H++TcO 4 +i(TBP)org←(HTcO1·iTBP)org, and (MLn·2TBP)org+TcO 4 ←(MLn−1TcO4·2TBP)org+L were established in the above systems. The extraction of pertechnetate ion is more effective when it is coordinated to a cation solvated by TBP than the extraction in the form of pertechnetate acid solvated by TBP.  相似文献   

3.
Thermal behaviour of nickel amine complexes containing SO4 2−, NO3 , Cl and Br as counter ions and ammonia and ethylenediamine as ligands have been investigated using simultaneous TG/DTA coupled with mass spectroscopy (TG/DTA–MS). Evolved gas analyses detected various transient intermediates during thermal decomposition. The nickel ammonium sulphate complex produces NH, N, S, O and N2 species. The nickel ammonium nitrate complex generated fragments like N, N2, NO, O2, N2O, NH2 and NH. The halide complexes produce NH2, NH, N2 and H2 species during decomposition. The ligand ethylenediamine is fragmented as N2/C2H4, NH3 and H2. The residue hexaamminenickel(II) sulphate produces NiO with crystallite size 50 nm. Hexaammine and tris(ethylenediamine)nickel(II) nitrate produce NiO in the range 25.5 nm and 23 nm, respectively. The halide complexes produce nano sized metallic nickel (20 nm) as the residue. Among the complexes studied, the nitrate containing complexes undergo simultaneous oxidation and reduction.  相似文献   

4.
A new high-performance ion chromatography assay for organic and inorganic nitrogen analysis has been proposed and examined. In the devised protocol, inorganic sample constituents were measured after ultrasonically assisted water extraction. The amine and amide nitrogen content was assessed after modified Kjeldahl digestion and determined as NH4+, and the total nitrogen content was quantified as NO3 after microwave-facilitated digestion. Finally, the nitro, azo, azoxy nitrogen was calculated by comparison of the total nitrogen content and all measured nitrogen species. The detection limits of the measured ions were 2.0, 0.82 and 0.17 mg L−1 for nitrate, nitrite and ammonium, respectively. For samples of potatoes, the average shares of the nitrogen species found in the total nitrogen content were: 0.83% of nitrate nitrogen, <0.03% of nitrite nitrogen, 2.1% of ammonium nitrogen, 71% of nitro, azo, azoxy nitrogen, and 26% of amine, amide nitrogen. We expect the method to be applicable to different vegetable samples. The quality of the results obtained was verified by analyzing certified reference material and comparing to another analytical method.  相似文献   

5.
Performance of sulfate-dependent anaerobic ammonium oxidation   总被引:4,自引:0,他引:4  
The performance of sulfate-dependent anaerobic ammonium oxidation was studied. The results showed that both SO4 2− and NH4 + were chemically stable under anaerobic conditions. They did not react with each other in the absence of biological catalyst (sludge). The anaerobic digested sludge cultivated in an anaerobic reactor for three years took on the ability of oxidizing ammonium with sulfate anaerobically. The average reduction of sulfate and ammonium was 71.67 mg·L−1 and 56.82 mg·L−1 at high concentrations. The reaction between SO4 2− and NH4 + was difficult, though feasible, due to its low standard Gibbs free energy change. The experiment demonstrated that high substrate concentrations and low oxidation-reduction potential (ORP) may be favourable for the biological reaction. Supported by the National Natural Science Foundation of China (Grant No. 30770039) and the High-tech Research and Development Program of China (Grant No. 2006AA06Z332)  相似文献   

6.
Pulse radiolysis of acetonitrile solutions of tetra-n-butyl ammonium salts of 2- and 4-carboxybenzophenones [BP-COO···N+(C4H9)4] were performed in order to generate directly the reduced forms of the benzophenone moieties within pre-formed ion pairs. In earlier studies on photochemical electron transfer reactions, ion pairs containing a tetraalkyl ammonium cation and a benzophenone radical anion were formed in an electron transfer to the triplet BP from a quencher consisting of a tetraalkyl ammonium salt of (phenylthio)acetic acid. In the current work, the [BP•−COO···N+(C4H9)4] ion pairs were formed by direct reduction of the salts without the complication of a third moiety, i.e., the (phenylthio)acetic anion. The spectra and kinetic parameters of the radiolytically-reduced salts were compared to the behavior of reduced forms of the 2- and 4-COOH substituted benzophenones. The results from the pulse radiolysis and photochemistry were compared and explained in terms of the different structures of the ion pairs.  相似文献   

7.
Because Nitrosomonas europaea contains ammonia-oxidizing enzyme, nitrite reductase, and nitrous oxide reductase, the conversion of ammonia to dinitrogen was tried with different reaction conditions. In aerobic reaction conditions, ammonium was converted to nitrite (NO 2 ), while under oxygen-limiting or oxygen-free conditions, NO 2 -N formed from ammonia oxidation by N. europaea was reduced to N2O and dinitrogen with 22% conversion. During denitrification, optimal pH for the production of N2O and dinitrogen was found to be 7.0–8.0. Dinitrogen was not produced in acidic pH<7.0. A low partial oxygen pressure as well as oxygen-free conditions are favorable for high production of dinitrogen.  相似文献   

8.
The root explants of the germinated seedlings of Podophyllum hexandrum were grown in MS medium supplemented with indole acetic acid (IAA) (2 mg/L) and activated charcoal (0.5%), and healthy callus culture was obtained after incubation for 3 wk at 20°C. The cultivation of plant cells in shake flask was associated with problems such as clumping of cells and browning of media, which were solved by the addition of pectinase and polyvinylpyrrolidone. The effect of major media components and carbon source was studied on the growth and podophyllotoxin production in suspension culture. It was found that glucose was a better carbon source than sucrose and that NH4 +:NO3 ratio (total nitrogen concentration of 60 mM) and PO4 3− did not have much effect on the growth and product formation. The relative effect of culture parameters (inoculum level, pH, IAA, glucose, NH4 +:NO3 ratio, and PO4 3−) on the overall growth and product response of the plant cell suspension culture was further investigated by Plackett-Burman design. This indicated that inoculum level, glucose, IAA, and pH had significant effects on growth and production of podophyllotoxin. To identify the exact optimum concentrations of these parameters on culture growth and podophyllotoxin production, central composite design experiments were formulated. The overall response equations with respect to growth and podophyllotoxin production as a function of these culture parameters were developed and used to determine the optimum concentrations of these parameters, which were pH 6.0, 1.25 mg/L of IAA, 72 g/L of glucose, and inoculum level of 8 g/L.  相似文献   

9.
The tetranitrosyl iron complex with pyridine-2-yl [Fe2(SC5H4N)2(NO)4] (1) has higher NO-donating activity in 3% aqueous solutions of DMSO (pH 7.0, 25 °C) than the organic NO donor, viz., adduct of NO with diethylenetriamine (NO-adduct). The NO concentration was determined by the spectrophotometric method based on the formation of an NO complex with hemoglobin (Hb). The apparent first-order rate constants of the studied reactions are (6.15±0.6)·10−1 s−1 and (0.8±0.08)·10−1 s−1 for complex 1 and the NO-adduct, respectively, at an Hb concentration of 2·10−1 mol L−1 and the ratio [NO donor]/[Hb] = 10. The effect of Hb and [NO donor]/[Hb] ratio on the rate of NO generation from a solution of complex 1 was studied. For a fourfold decrease in the concentration of complex 1 the reaction rate constant decreases to 0.5·10−4 s−1, whereas the fourfold increase in the Hb concentration results in the stabilization of complex 1. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 732–736, April, 2007.  相似文献   

10.
The reaction of the · OH radical with the oxalate ion in an acidic aqueous solution was studied by pulse radiolysis. The rate constant for the reaction of formation of the radical HOOC-COO·(λmax = 250 nm, ɛ = 1800 L mol−1 cm−1) is (5.0±0.5)·107 L mol−1 s−1. In the reaction with the hydrogen ion (k = 1.1·107 L mol−1 s−1), the radical HOOC-COO· is transformed into a nonidentified radical designated arbitrarily as H+(HOOC-COO)· (λmax = 260 nm, ɛ = 4000 L mol−1 cm−1). Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1165–1167, June, 2008.  相似文献   

11.
Summary A capillary electrophoretic method for the simultaneous separation of nitrate, nitrite and ammonium has been developed. Direct (NO3 , NO2 ) and indirect (NH4 +) UV detection at 214 nm in conjunction with electromigration sampling from both ends of the capillary was used. Two electrolyte systems based on imidazole-sulfate (pH 3.8) and copper(II)-ethylenediamine-chloride (pH 8.0) were investigated. Optimisation of the experimental parameters such as electrolyte concentration, pH, nature of the counter-ion, was studied. The method permits excellent separation of three nitrogen species in only 4 min. The analytical performance of both electrolyte systems is compared in terms of migration time and peak area repeatability and detectability. Alkaline electrolyte shows a better overall analytical performance.  相似文献   

12.
This work reports on the removal of organic matter and nitrogen in a radial-flow aerobic-anoxic immobilized biomass (RAIB) reactor fed with domestic sewage pretreated in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor. Polyurethane foam was used as support material for biomass attachment in both reactors. In batch experiments, a first-order kinetic model with residual concentration represented the organic matter removal rate, whereas nitrogen conversion followed a pseudo-first-order reaction in series model, with kinetic constants k 1 (ammonium to nitrite) and k 2 (nitrite to nitrate) of 0.25 and 6.62 h−1, respectively. The RAIB reactor was operated in continuous-flow mode and changes in the airflow rate and hydraulic retention time were found to interfere in the apparent kinetic constants to the nitritation (k 1) and nitratation (k 2). Nitrification and denitrification were achieved in the partially aerated RAIB reactor operating with hydraulic retention times of 3.3 h and 2.7 h in the aerobic and anoxic zones, respectively. Ethanol was added in the anoxic zone of the reactor to promote denitrification. The effluent flow of the RAIB reactor presented a COD of 52 mg l−1, and concentrations of 2 mg , 1.24 mg and 3.46 mg .  相似文献   

13.
The structure of tetraaqua-bis(nitrato-O,O′)-(1,10-phenanthroline-N,N′)-lanthanum(III) 1,3,5,7-tetraazatricyclo[3.3.1.13,7]decane nitrate dihydrate, [La(NO3)2 · phen · (H2O)4]+ · hmt · NO 3 · 2H2O, is presented. The lanthanum ion exhibits tenfold coordination and the polyhedron can be described as tetradecahedron. The complex cations, nitrate ions, water and hexamethylenetetramine molecules are assembled via hydrogen bonds, H–π rings and ππ stacking interactions into 3D supramolecular network. The bond strength of coordination sphere was calculated by means of the bond-valence method. The influence of La:phen stoichiometry and additional ligand on the changes of lanthanum(III) coordination sphere geometry in ten-coordinated complexes with 1,10-phenanthroline was discussed. The infrared spectrum of structure optimised by means of quantum mechanical calculations was analysed and compared with measured one. The obtained compound was characterised by thermogravimetric analysis in conjunction with evolved gases in the air atmosphere.  相似文献   

14.
Leachate recirculation allows an increase of moisture content and the enhancement of the anaerobic digestion of wastes in landfill. Since there is no ammonia elimination process in landfill when leachate is recirculated, NH(4) (+) may accumulate. One strategy for NH(4) (+) removal is to treat aerobically the leachate outside the landfill to convert NH(4) (+) into NO(3) (-). When nitrified leachate is recirculated, denitrification should occur in the waste. We have previously shown that wastes have a large capacity to convert nitrate into N(2). Nevertheless, in some cases we observed nitrate reduction without gaseous nitrogen production. Using a stepwise multiple regression models, H(2)S concentration was the unique parameter found to have a negative effect on N(2) production. We then suspected that dissimilatory nitrate reduction to ammonium (DNRA) occurred in the presence of H(2)S. In order to verify this hypothesis, (15)N nitrate injections were performed into microcosms containing different H(2)S concentrations. The ammonium (15)N enrichment was measured using an elemental analyser coupled to an isotope ratio mass spectrometer. In the two microcosms containing the highest H(2)S concentrations, the ammonium was (15)N enriched and at the end of the experiment all the added nitrate was converted into ammonium. For the two microcosms containing the lowest H(2)S concentrations, no (15)N enrichment of ammonium was observed. This isotopic approach has allowed us to demonstrate that, in the presence of significant concentrations of H(2)S, denitrification is replaced by DNRA.  相似文献   

15.
阴阳离子双隔膜三室电解槽电渗析处理垃圾渗滤液   总被引:4,自引:0,他引:4  
陈日耀  陈震  耿亚敏  郑曦  陈晓 《应用化学》2009,26(11):1336-1340
采用阴阳离子双隔膜三室电解槽,将电渗析技术与Fenton试剂法结合,去除垃圾渗滤液中氨氮和CODCr。垃圾渗滤液中的氨氮通过电渗析技术富集到阴极液中,随后用化学沉淀法加以去除。同时,在铁阳极上生成的Fe2+离子,与滴加入阳极液中的H反应生成Fenton试剂,降解有机物,降低CODCr。实验结果表明,模拟废水中的氨氮透过率达80%,垃圾渗滤液中氨氮浓度和CODCr由原来的1982和2248 mg/L分别降至200和127 mg/L。  相似文献   

16.
The kinetics of the peroxy radicals RHFO2 reactions with NO has been studied by using pulse radiolysis and UV absorption spectroscopy. The rate constants of interaction of oxygen atoms with NO − k 2 = 2.2±0.2·10−12 cm3·s−1 and NO2k 3 = 2.1±0.2·10−11 cm3·s−1 were found in agreement with the literature values. The bath gases (SF6 or CO2) have got minor effect on the rate constants of RHFO2+NO→NO2+prod. reactions; RHFO2 = CH3CH2O2, CH3CHFO2, CH3CF2O2, CF3CH2O2, CF3CHFO2. The obtained rate coefficients are in the scope of the literature values, although they are lower than those recommended in NIST database. The reasons are discussed.  相似文献   

17.
The use of appreciable H-D isotope effects in the infrared spectra of normal and deuterated salts of tri-n-octyl amine (TOAHX or TAODX, where X=Cl, Br, I, HSO4, NO3 and ClO4), the investigation of the chemical shift of the NH proton in NMR spectra, the results of chemical analysis (H2 O, D2 O acid) and the osmometrical data allow to explain some questions concerning the structure and to discuss the strength of the hydrogen bonds in associates TOAH+X and their hydration. From this comparison it follows that the strength of hydrogen bond in TOAH+X (TOAD+X) increases in the order of ClO 4 <HSO 4 <IBr<NO 3 <Cl. H-D isotope effects are discussed in the association of these salts.  相似文献   

18.
Sorption behaviour of monovalent Rb+, Tl+ and Ag+ is studied on chromium fericyanide gel. Log Kd vs log concentration plots show that Rb+ and Tl+ are sorbed through ion exchange mechanism in a higher concentration range of ammonium nitrate or nitric acid, whereas the adsorption of Ag+ is irreversible. It was found possible to elute Rb+ and Tl+ on the columns of this gel by 4 mol dm−3 NH4NO3 and 10 mol dm−3 HNO3, respectively. Binary separations of Rb+ and Tl+ from a number of other metal ions were achieved as other ions were found practically unadsorbed on these columns and were eluted with water of pH 2–3. Achieved separations are of radioanalytical and analytical importance.  相似文献   

19.
An efficient ion chromatographic (IC) method was developed for the simultaneous quantitative determination of Li+, Na+, NH4 +, K+, Cs+, Ca2+, Mg2+, Sr2+, Ba2+ and Be2+ in energy drinks, pharmaceutical and drinking water samples by non-suppressed conductometric detection. The separation of ten cations including ammonium was achieved using a cation-exchange column and low conductivity mobile phase. The mobile phase consisted of tartaric acid, dipicolinic acid and boric acid. The separation of the cations was completed in less than 18 min, with a flow rate of 1.2 mL min−1. The separation was not affected by the existence of cations Co2+, Cr3+, Cd2+, Cu2+, Bi3+, Ag+, Fe3+ and Zn2+ in concentrations up to 20 mg L−1. Using an injection volume of 20 μL the obtained detection limits were 0.003 mg L−1, 0.02 mg L−1, 0.01 mg L−1, 0.01 mg L−1, 0.10 mg L−1, 0.01 mg L−1, 0.02 mg L−1, 0.02 mg L−1, 0.003 mg L−1 and 0.1 mg L−1, for Li+, Na+, NH4+, K+, Cs+, Ca2+, Mg2+, Sr2+, Be2+ and Ba2+ respectively. The intra-day repeatability (RSD%, n=5) ranged from 1.1% to 4.8%, and the inter-day (n=5) between 1.8% and 5.4% respectively. The method was applied to the analysis of various bottled and tap water, pharmaceutical preparations and energy drinks commercially available.   相似文献   

20.
Nitrate ions were used as the oxidant in the cathode chamber of a microbial fuel cell (MFC) to generate electricity from organic compounds with simultaneous nitrate removal. The MFC using nitrate as oxidant could generate a voltage of 111 mV (1,000 Ω) with a plain carbon cathode. The maximum power density achieved was 7.2 mW m−2 with a 470 Ω resistor. Nitrate was reduced from an initial concentration of 49 to 25 mg (NO3−N) L−1 during 42-day operation. The daily removal rate was 0.57 mg (NO3–N) L−1 day−1 with a voltage generation of 96 mV. In the presence of Pt catalyst dispersed on cathode, the cell voltage was significantly increased up to 450 mV and the power density was 117.7 mW m−2, which was 16 times higher than the value without Pt catalyst. Significant nitrate removal was also observed with a daily removal rate of 2 mg (NO3–N) L−1 day−1, which was 3.5 times higher compared with the operation without catalyst. Nitrate was reduced to nitrite and ammonia in the liquid phase at a ratio of 0.6% and 51.8% of the total nitrate amount. These results suggest that nitrate can be successfully used as an oxidant for power generation without aeration and also nitrate removal from water in MFC. However, control of the process would be needed to reduce nitrate to only nitrogen gas, and avoid further reduction to ammonia.  相似文献   

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