Study on dynamic characteristics of cavitation in underwater explosion with large charge.

Underwater explosions (UNDEX) generate shock waves that interact with the air-water interface and structures, leading to the occurrence of rarefaction waves and inducing cavitation phenomena. In deep-water explosions, complex coupling relationships exist between shock wave propagation, bubble motion, and cavitation evolution. The shock wave initiates the formation of cavitation, and their growth and collapse are influenced by the pressure field. The collapsing bubbles generate additional shock waves and fluid motion, affecting subsequent shock wave propagation and bubble behavior. This intricate interaction significantly impacts the hydrodynamic characteristics of deep-water explosions, including pressure distribution, density, and phase changes in the surrounding fluid. In this paper, we utilize a two-fluid phase transition model to capture the evolution of cavitation in deep-water explosions. Our numerical results demonstrate that the introduction of a two-phase vapor-liquid phase change model is necessary to accurately capture scenarios involving prominent evaporation or condensation phenomena. Furthermore, we find that the cavitation produced by the same charge under different explosion depths exhibits significant differences, as does the peak value of cavitation collapse pressure. Similarly, the cavitation produced by different charge quantities under the same explosion depth varies, and the relationship between cavitation volume and charge quantity is not a simple linear increase. The research methods and results presented in this paper provide an important reference for studying the dynamic characteristics of deep-water explosions.

[Metabolomic interference induced by short-chain chlorinated paraffins in human normal hepatic cells].

Short-chain chlorinated paraffins (SCCPs) are an emerging class of persistent organic pollutants (POPs) that are widely detected in environmental matrices and human samples. Because of their environmental persistence, long-range transport potential, bioaccumulation potential, and biotoxicity, SCCPs pose a significant threat to human health. In this study, metabolomics technology was applied to reveal the metabolomic interference in human normal hepatic (L02) cells after exposure to low (1 µg/L), moderate (10 µg/L), and high (100 µg/L) doses of SCCPs. Principal component analysis (PCA) and metabolic effect level index (MELI) values showed that all three SCCP doses caused notable metabolic perturbations in L02 cells. A total of 72 metabolites that were annotated by MS/MS and matched with the experimental spectra in the Human Metabolome Database (HMDB) or validated by commercially available standards were selected as differential metabolites (DMs) across all groups. The low-dose exposure group shared 33 and 36 DMs with the moderate- and high-dose exposure groups, respectively. The moderate-dose exposure group shared 46 DMs with the high-dose exposure group. In addition, 33 DMs were shared among the three exposure groups. Among the 72 DMs, 9, 9, and 45 metabolites participated in the amino acid, nucleotide, and lipid metabolism pathways, respectively. The results of pathway enrichment analysis showed that the most relevant metabolic pathways affected by SCCPs were the lipid metabolism, fatty acid ß-oxidation, and nucleotide metabolism pathways, and that compared with low-dose exposure, moderate- and high-dose SCCP exposures caused more notable perturbations of these metabolic pathways in L02 cells. Exposure to SCCPs perturbed glycerophospholipid and sphingolipid metabolism. Significant alterations in the levels of phosphatidylcholines, phosphatidylethanolamines, and sphingomyelins indicated SCCP-induced biomembrane damage. SCCPs inhibited fatty acid ß-oxidation by decreasing the levels of short- and medium-chain acylcarnitines in L02 cells, indicating that the energy supplied by fatty acid oxidation was reduced in these cells. Furthermore, compared with low- and moderate-dose SCCPs, high-dose SCCPs produced a significantly stronger inhibition of fatty acid ß-oxidation. In addition, SCCPs perturbed nucleotide metabolism. The higher hypoxanthine levels observed in L02 cells after SCCP exposures indicate that SCCPs may induce several adverse effects, including hypoxia, reactive oxygen species production, and mutagenesis in L02 cells.

[New pretreatment method for detecting petroleum hydrocarbons in soil: silica-gel dehydration and cyclohexane extraction].

Oil is a primary source of energy worldwide. However, the use of oil produces large amounts of pollutants, which are detrimental to the environment. The presence of petroleum hydrocarbons in soil is a critical marker of environmental pollution and safety. Rapid on-site detection technology has been broadly used in emergency tracking, offering critical information support for effective reactions to environmental emergencies. Thus, it is expected to play an increasingly critical role in environmental remediation efforts. The current approach for petroleum hydrocarbon detection in soil mainly involves Soxhlet extraction with a combination of solvents, including acetone and n-hexane. The samples are then analyzed after rotary evaporation, dehydration with anhydrous sodium sulfate, and purification using a magnesium silica-type adsorbent. Unfortunately, this approach requires sample analysis to be performed in the laboratory, which is tedious and time consuming, and consumes large amounts of solvents. Moreover, the rotary evaporator is not portable. Therefore, this method is not appropriate for the rapid on-site detection of petroleum hydrocarbons. In this study, a rapid on-site detection method based on silica-gel dehydration and cyclohexane extraction was developed for the extraction and pretreatment of petroleum hydrocarbons (C10-C40) in soil. First, an appropriate amount of silica gel was added to the soil, and the mixture was completely ground to eliminate moisture. Next, petroleum hydrocarbons were extracted with 40 mL of cyclohexane, and the extract was cleaned by Florisil solid-phase extraction (SPE) column elution. Finally, the samples were analyzed by gas chromatography (GC) to evaluate the above method. The silica gel exhibited optimal adsorption properties compared with anhydrous sodium sulfate, calcium oxide, and molecular sieves, with recovery of 87.5%. The effects of different soil water content (5%, 10%, and 20%) and silica gel (1, 3, 5, and 10 times the moisture content) dosage on the extraction of petroleum hydrocarbons were investigated. The recoveries of petroleum hydrocarbons increased from 74.0% to 103.8% after 15 min of invasive extraction (relative standard deviation, RSD, <10.1%) when silica gel amounting to 10 times the moisture content was used. Five types of silica gels with different properties were purchased from four manufacturers, and the effects of these silica gels on the dehydration and extraction efficiency of petroleum hydrocarbons in soil were assessed. The results showed that amorphous silica gel led to low recoveries (<60%), spherical silica gel achieved extraction efficiencies of approximately 70%-90%, and alkaline silica gel produced recoveries with poor precision. Therefore, neutral spherical silica gel was used for further experiments. The fingerprints of petroleum hydrocarbons with different carbon numbers are an important reference for identifying pollution sources. Thus, ensuring good recoveries throughout the entire carbon range is necessary to ensure the accuracy of the fingerprint analysis results. The proposed method showed good recoveries for petroleum hydrocarbons of all carbon numbers (75%-101%). The findings above indicate that the developed method could be an efficient means to extract petroleum hydrocarbons from soil for both total quantity and fingerprint analyses. Compared with standard methods, the proposed method requires lower solvent dosages and features simpler processing steps. Another advantage of this method is that it does not require the use of highly toxic halogenated solvents; thus, it does not contribute to environmental pollution. It can be applied to the laboratory analysis of soil petroleum hydrocarbons and coupled with other rapid on-site detection techniques for soil petroleum hydrocarbons, such as infrared spectroscopy and portable GC. However, because it does not include a concentration process, the developed method exhibits relatively low sensitivity. In the future, we plan to develop a simple and flexible on-site sample-concentration system to further improve various indicators of this method.

[Determination of short- and medium-chain chlorinated paraffins in different components of human blood using gas chromatography-electron capture negative ion-low resolution mass spectrometry].

Short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) have attracted significant attention because of their persistence, biotoxicity, bioaccumulation, and long-range migration. Given their worldwide detection in a variety of environmental matrices, concerns related to the high exposure risks of SCCPs and MCCPs to humans have grown. Thus, knowledge of the contamination patterns of SCCPs and MCCPs and their distribution characteristics in the vivo exposure of humans is of great importance. However, little information is available on the contamination of SCCPs and MCCPs in human blood/plasma/serum, mainly because of the difficulty of sample preparation and quantitative analysis. In this study, a new blood sample pretreatment method based on Percoll discontinuous density gradient centrifugation was developed to separate plasma, red blood cells, white blood cells, and platelets from human whole blood. A series of Percoll sodium chloride buffer solutions with mass concentrations of 1.095, 1.077, and 1.060 g/mL were placed in a centrifuge tube from top to bottom to establish discontinuous density gradients. The dosage for each density gradient was 1.5 mL. Human whole blood samples mixed with 0.85% sodium chloride aqueous solution were then added to the top layer of the Percoll sodium chloride solution. After centrifugation, the whole blood was separated into four components. The plasma was located at the top layer of the centrifuge tube, whereas the platelets, white blood cells, and red blood cells were retained at the junction of the various Percoll sodium chloride solutions. The sampling volume of human whole blood and incubation time were optimized, and results indicated that an excessively long incubation time could lead to hemolysis, resulting in a decrease in the recoveries of SCCPs and MCCPs. Therefore, a sampling volume of 1.5 mL and incubation time of 10 min at 4 ℃ were adopted. The cells of the blood components were further broken and extracted by ultrasonic pretreatment, followed by multilayer silica gel column chromatography for lipid removal. The use of 80 mL of n-hexane-dichloromethane (1∶1, v/v) and 50 mL of dichloromethane as the elution solvents (collected together) for the gel column separated the SCCPs and MCCPs from the lipid molecules in the blood samples. Gas chromatography-electron capture negative ion-low resolution mass spectrometry (GC-ECNI-LRMS) was used to determine the SCCPs and MCCPs. Quantification using the corrected total response factor with degrees of chlorination was achieved with linear corrections (R2=0.912 and 0.929 for the SCCPs and MCCPs, respectively). The method detection limits (MDLs) for the SCCPs and MCCPs were 1.57 and 8.29 ng/g wet weight (ww, n=7), respectively. The extraction internal standard recoveries were 67.0%-126.6% for the SCCPs and 69.5%-120.5% for the MCCPs. The developed method was applied to determine SCCPs and MCCPs in actual human whole blood samples. The contents of SCCPs and MCCPs were 10.81-65.23 and 31.82-105.65 ng/g (ww), respectively. Red blood cells exhibited the highest contents of CPs, followed by plasma, white blood cells, and platelets. The proportions of SCCPs and MCCPs in red blood cells and plasma were 70% and 66%, respectively. In all four components, the MCCP contents were higher than the SCCP contents, and the ratios of MCCPs to SCCPs ranged from 1.04 to 3.78. Similar congener patterns of SCCPs and MCCPs were found in the four components of human whole blood. C10-CPs and C14-CPs were predominantly observed in the SCCPs and MCCPs, respectively. In summary, a simple and efficient method was proposed to determine low concentrations of SCCPs and MCCPs in human blood with high sensitivity and selectivity. This method can meet requirements for the quantitative analysis of SCCPs and MCCPs in human blood components, thereby providing technical support for human health risk assessment.

[Accumulation Characteristics and Dietary Exposure Estimation of Heavy Metals in Vegetables from the Eastern Coastal Region of China].

The levels of six toxic metals and five essential metals in five groups of vegetables marketed in the eastern coastal region of China were analyzed using inductively coupled plasma mass spectrometry. The results showed that the concentrations of six toxic heavy metals in all the vegetables did not exceed the maximum residue limits. The health risk assessment indicated that consumption of vegetables may not pose a potential noncarcinogenic risk to consumers, while there is a carcinogenic risk level of 10-5 level from inorganic arsenic exposure through vegetable consumption. Additionally, a similar trend was observed for the accumulation of toxic and essential metals. Furthermore, compared with other vegetable groups, edible fungi have a high potential to accumulate toxic and essential metals, which indicates that pollution monitoring of edible fungi should be strengthened.

[Simultaneous Removal of Polychlorinated Dibenzo-p-dioxins/dibenzofurans, Polychlorinated Biphenyls, and Polychlorinated Naphthalenes From Flues Gases From Coke Gas Burning Using Selective Catalytic Reduction Equipment].

The removal efficiencies of typical unintentionally produced persistent organic pollutants (UP-POPs) from flues gases from coke gas burning were obtained using selective catalytic reduction (SCR) equipment installed in a large coking plant. The total congeners of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polychlorinated naphthalenes (PCNs) in the flue gases at the inlet and outlet of the SCR equipment and the dustfall were analyzed. The results show that the removal efficiency of the total PCDD/Fs was the highest (94.6%). The removal efficiencies of total PCBs and total PCNs were 74.7% and 78.4%, respectively. The homologue profile of UP-POPs in the flue gases at the inlet of the SCR equipment notably differed from that at the outlet. Highly chlorinated UP-POPs predominated over the homologue profile of UP-POPs in the inlet flue gas, while low-chlorinated UP-POPs were predominant in the outlet flue gas. The SCR equipment achieved a better removal efficiency with respect to highly chlorinated UP-POPs. Catalytic reduction and catalytic oxidation degradation are both important mechanisms for the removal of UP-POPs from flue gas using SCR equipment.

[Treatment of lactic acidosis with early continuous blood purification].

OBJECTIVE: To observe the therapeutic effect of early continuous blood purification (CBP) on lactic acidosis patients. METHODS: Using prospective randomized study method, 41 patients with lactic acidosis in intensive care unit (ICU) from January 2010 to April 2012 were randomly divided into CBP group (n=21) and control group (n=20). Among them, blood gas analysis, lactic acid, blood biochemistry were prospectively monitored at the time before treatment, 12, 24 and 72 hours after treatment. They were also evaluated with acute physiology and chronic health evaluation II (APACHEII) score, and length of stay in ICU and mortality in 28 days were recorded. RESULTS: Lactic acid level and APACHEII score were gradually decreased after treatment in both groups. Compared with control group, lactic acid at 12, 24 and 72 hours in CBP group was obviously lowered (12 hours: 8.23±3.94 mmol/L vs. 12.47±4.62 mmol/L, 24 hours: 4.46±1.57 mmol/L vs. 10.54±3.48 mmol/L, 72 hours: 2.69±1.03 mmol/L vs. 5.74±1.56 mmol/L, all P<0.01), while the APACHEII score at 12, 24 and 72 hours in CBP group was also significantly lowered (12 hours: 18.23±5.85 vs. 21.64±5.38, 24 hours: 16.49±4.62 vs. 20.61±5.71, 72 hours: 11.54±3.67 vs. 16.02±4.34, all P<0.05). Compared with control group, length of stay in ICU was also significantly shorter in CBP group (6.58±3.45 days vs. 11.65±4.94 days, P<0.05), and 28-day mortality was significantly lower in CBP group (23.8% vs. 45.0%, P<0.05). CONCLUSION: Early correction of lactic acidosis with CBP could reduce the mortality of lactic acidosis.

[Analysis of short-chain chlorinated paraffins in sediment samples from the mouth of the Daliao River by HRGC/ECNI-LRMS].

An analytical method for quantifying short-chain chlorinated paraffins (SCCPs) by high-resolution gas chromatography/electron capture negative ion low-resolution mass spectrometry (HRGC/ECNI-LRMS) was presented. The cleanup procedure with an acid silica gel column and activated neutral alumina column was optimized to remove the interferences. As illustration of the application of the method to environmental samples, it is found that lower chlorinated C10 and C11 compounds were the main SCCPs compounds in six sediment samples from the mouth of the Daliao River. The concentrations of SCCPs in sediments were determined to be in the range of 64.9-407.0 ng/g and showed a decreasing tendency from the shore to the remote location.

[PCDD/Fs formation from pentachlorobenzene under the catalysis of CuO].

The formation processes of PCDD/Fs from pentachlorobenzene catalyzed by CuO under heating conditions were investigated. The results showed that, the amount of the formed PCDD/Fs increased with the temperature from 200 degrees C to 350 degrees C, and then decreased with futher increase of temperature from 350 degrees C to 450 degrees C. PCDD/Fs homologue pattern varied significantly according to the reaction temperature. At the lower temperature (200-250 degrees C), the major PCDD/Fs products were highly chlorinated ones; but at the higher temperature (400-450 degrees C), the low chlorinated PCDD/Fs predominated in the PCDD/Fs products. The change of temperature did not cause a systematical variation in the isomer distributions in each PCDD/Fs homologue. By comparing the formation of PCDD/Fs from pentachlorobenzene with the dechlorination of OCDD/F both under the catalysis of CuO at 400 degrees C, the precursor mechanism of PCDD/ Fs formation from pentachlorobenzene was speculated. Low chlorinated PCDDs mainly came from the dechlorination of highly chlorinated PCDDs which were formed from the pentachlorobenzene, whereas PCDFs could be mainly formed by the direct condensation of dechlorination products of pentachlorobenzene.

[PCDD/F emission characteristics in different waste incineration facilities and evaluation of 23478-PeCDF as I-TEQ indicator of PCDD/F in flue gases].

The emission characteristics of PCDD/F from different waste incineration facilities in China, the correlations of different PCDD/F isomers with I-TEQ and the linear regression analysis of 23478-PeCDF with I-TEQ were reported in this article. Statistical analysis of the homologue patterns of PCDD/F in different incineration facilities will provide valuable information in environmental survey to find the contamination sources. PCDD/F congener patterns were almost constant among municipal and hazardous waste incineration facilities with only very small variations, but those patterns in medical waste incineration facilities were slightly different from medical and hazardous waste incineration facilities. It was found that the major contributors to the toxic PCDD/F concentrations were OCDD and 1234678-HpCDF contributing for 12.3%-23.0% and 15.0%-19.7% respectively. However, the largest contributor to I-TEQ was 23478-PeCDF and 33.1%-34.5% of I-TEQ was the presence of this congener. Correlation analysis showed that:23478-PeCDF posed the best the correlation relationship with I-TEQ, R2 0.93-0.99. The most toxic 2378-TCDD only posed weak correlation with I-TEQ, R2 0.29-0.49. The correlation coefficient between the most abundant OCDD and I-TEQ was only 0.03-0.12. However, another abundant congener 1234678-HpCDF posed better correlation with I-TEQ, R2 0.62-0.87. Linear regression analysis showed that even I-TEQ fell into the concentration range of 5-6 orders of magnitudes, the linear relationship between 23478-PeCDF and I-TEQ was still excellent. The slopes of that lines, in different waste incineration facilities, were in the range of 1.16-1.40 and R2 0.94-0.97.

[Patterns of PCDD/Fs, PCBs and PCNs homologues in fly ash from cement kilns].

The concentrations and toxic equivalent (TEQ) values of PCDD/Fs, PCBs and PCNs in fly ash collected from three types of cement kilns (vertical shaft kiln, wet-process rotary kiln and dry-process rotary kiln) and two types of waste incinerators were determined, and the patterns of homologues and congeners were compared. The results showed that the total TEQ of PCDD/Fs, PCBs and PCNs in cement kiln fly ash, which were in the range of 4.0-62, 0.069-3.9 and 0.47-2.8 ng x kg(-1) respectively, were much lower than that of fly ash from waste incinerators. In cement kiln fly ash, the predominating PCDD/Fs homologues were TCDFs, and the chief 2, 3, 7, 8-PCDD/Fs congeners were OCDD, 2, 3, 7, 8-TCDF and 1, 2, 3, 4, 6, 7, 8-HpCDF. The patterns of PCBs homologues in cement kiln fly ash were similar to those of waste incinerators in which TeCB were predominating homologues. PCB77, PCB105, PCB118 were at higher concentrations than other co-polar PCBs. Different types of cement kiln fly ash presented similar PCNs homologue patterns. The predominant homologues were TeCN, whereas OcCN were not detected. PCN 66/67 which has dioxin like toxity was the most abundant congener in all fly ash.

[Distribution and pollution character of heavy metals in the surface sediments of Liao River].

The concentrations of 7 heavy metals (Ni, Cu, Cr, Pb, Cd, As, Hg) and organic matters in the surface sediments of Liao River were determined by atomic absorption spectrometry (AAS) and atomic fluorescence spectrometry (AFS), and sediments pollution assessment was carried out using geoaccumulation index. Moreover, the sources of heavy metal contamination were estimated with the principal component analysis (PCA). The results demonstrate that the heavy metal concentrations of Liao River are markedly higher than that of Liao River in 1998 and lay at medium level compared with other rivers in China. The average concentrations (mg/kg) obtained were: Ni 26.5 mg x kg(-1), Cu 37.9 mg x kg(-1), Cr 90.3 mg x kg(-1), Pb 32.9 mg x kg(-1), Cd 0.49 mg x kg(-1), As 12.3 mg x kg(-1), Hg 0.14 mg x kg(-1). The results of geoaccumulation index reveal that sediments of Liao River are uncontaminated with Ni, As, lightly contaminated with Cu, Cr, Pb and moderately contaminated with Cd, Hg. The order of the analyzed heavy metals, arranged from the highest to lowest pollution degree, is as follows Cd > Hg > Cu > Cr > Pb > As > Ni. By estimating the sources of heavy metal contamination with the Principal component analysis (PCA), it was found that the first two components account for 58.74% and 17.18% of the total variance, respectively. The industrial and living wastewater, degradation of organic matter atmospheric precipitation and geochemical changes are the main sources of heavy metal contamination.

[Thermal desorption behavior of PCDD/Fs on the fly ash].

The article studied the thermal desorption behavior of PCDD/Fs on the fly ash under anoxic conditions. From the analysis of the PCDD/Fs concentrations in the gas phrase and solid residual, the several kinds of potential chemical reaction and physical changes of dioxin that occur at the different temperature are concluded. At the same time, desorption ratios of 17 toxic dioxin congers and the better desorption conditions are studied. At 200 degrees C and 300 degrees C, the average desorption ratio of PCDD/Fs are 96.2% and 95.5% respectively. At 400 degrees C, the average desorption ratio of PCDD/Fs is 99.7%. The experiment results show that the PCDD/Fs is dechlorinated at 300 degrees C. At 400 degrees C, a lot of precursor reactions happen in the fly ash, which enhance the content of PCDD/Fs.

[PCDD/F formation and its mass balance in a MSW incineration system].

PCDD/F distributions in a two-stage reciprocating grate municipal solid waste (MSW) incinerator under two kinds of operating conditions were investigated by sampling the ashes, flue gases and bottom ashes at different positions, and the mass balance was calculated. At the boiler outlet, the concentration of PCDD/F in the flue gas is 2.602 ng x m(-3) and 1.236 ng x m(-3) under operating condition 1 (RUNI) and operating condition 2 (RUN2), respectively. A significant formation of PCDD/F was found in the sections of semi-dry scrubber (SDS) and cyclone precipitator (CP), in which the temperature of flue gas was in the range of 260-180 degrees C. Compared with PCDD/F level measured at the boiler outlet, the total concentration of tetra-to octa-CDD/F measured at the CP outlet increased 82.2% and 17.6% under RUN1 and RUN2, respectively. At the bag filter (BF) section, about 90% of PCDD/F was removed from the flue gas by the precipitation of fly ash. The PCDD/F homologue patterns were almost similar for the boiler ash, CP ash, BF ash and the flue gases. The higher O2 content in flue gas led to a larger PCDD/F yield, but the variation of O2 level did not give rise to a systematical change of PCDD/F homologue pattern. Under RUN1, 10.4%, 3.2%, 9.3%, 64.1% and 13.0% of formed tetra-to octa-CDD/F were distributed into bottom ash, boiler ash, CP ash, BF ash and emission gas, respectively. The corresponding values were 8.6%, 8.0%, 9.4%, 66.7% and 7.3% for RUN2, respectively.

Influence of variation in the operating conditions on PCDD/F distribution in a full-scale MSW incinerator.

Optimizing the operating parameters to minimize polychlorodibenzo-p-dioxins and polychlorodibenzofurans (PCDD/F) emission is the common interest of the municipal solid waste (MSW) incineration industry. In this study, we investigated the distribution of tetra- to octa-CDD/F along the flue gas line in a full-scale reciprocating grate incinerator and evaluated the effects of temperature control and O(2) level on PCDD/F formation. Six runs were laid out and all performed under sufficient burning conditions, in which the combustion efficiency of MSW was more than 99.9%. The total concentration of tetra- to octa-CDD/F measured at the boiler outlet showed an increasing tendency with the increase of boiler outlet temperature (T(B)) from 214 degrees C to 264 degrees C. When flue gas ran across the semi-dry scrubber and cyclone precipitator, in which the temperature varied from 264 degrees C to 162 degrees C, the concentrations of the lower chlorinated dioxins and furans were significantly raised, especially for the TCDF. Increasing O(2) supply from 6.0% to 10.5% essentially led to a higher yield of tetra- to octa-PCDD/F, suggested that under sufficient burning conditions the lower O(2) level was favorable for reducing PCDD/F formation and emission. The variation of O(2) level did not give rise to a systematical change of PCDD/F homologue pattern. For all measurements, the isomer distributions of tetra- to hepta-PCDD/F were more or less the same, nearly independent of variations in the operating conditions and sampling positions. Only the significant increase of the sum of 1,3,7,8-TCDF and 1,3,7,9-TCDF was found in the zone after the boiler section.

[Stabilization of heavy metals in municipal solid waste incineration fly ash with the thiol collectors].

Three kinds of thiol collector, sodium diethyldithiocarbamate (DDTC), potassium ethyl xanthate (EXT) and ammonium dibutyl dithiphosphate (DDTP), were adopted to stabilize heavy metals from municipal solid waste incineration fly ash (MSWI fly ash). The concentration of the three thiol collectors was all 62.5 micromol x g(-1) fly ash. Scanning electron microscopic observation shows that, the thiol collectors evenly cover on the surface of fly ash which makes the angles of mineral crystal ambiguous. Furthermore, the leaching characteristics of heavy metal Cu, Pb, Cd, Cr and Zn in fly ash were analyzed according to the toxicity characteristic leaching procedure (TCLP) and the horizontal vibration method. Comparing with Na2S, thiol collectors present better stabilization effects for Cu and Pb when the extractant is 0.1 mol x L(-1) acetic acid. DDTC stabilizes almost all the acid-extractable Cu, and DDTP stabilizes 69.2% of acid-extractable Pb. When extracted by water, the stabilization ratios of the five heavy metals by DDTC, EXT and DDTP are 72.6%, 73.5% and 76.8%, respectively, significantly higher than that by Na2S (52.4%). The affinity preference of the thiol collectors for the five heavy metals is generally in the order of Cu > Pb > Cr > Cd > Zn. Also, over 60% of the collector participates in the chelating reaction with the acid-extractable heavy metals. Under neutral and alkali condition (pH > 6) the chelators of heavy metal-thiol collector are steady, but partly dissolved under acid condition (pH < 6). Evidently, in order to obtain better heavy metal stabilization effects, it is important to maintain the acid buffer capacity of stabilized fly ash at a higher level.

[Determination of anions in the products of ozonation of reactive dye by ion chromatography].

A method for the determination of anions in the degradation products of C. I. Reactive Red 120 by ozonation was investigated. The sample can be pretreated with a Dionex OnGuard P column, which has high selectivity for removing phenols, azo group-contaning compounds, aromatic carboxylic aicds etc. For the separation of organic and inorganic anions in the products, the anion exchange chromatograhy with gradient elution of NaOH was used. All the species were detected by both suppressed conductivity and UV absorbance detectors. The sulfate, oxalate, chloride, nitrate and formate could be identified even in very low concentration with ion chromatography, within 18 min, with the recoveries between 91.6% - 108.3%. The results indicate that the method is reliable, simple, rapid and especially sensitive. In combining with the determination results of conventional parameters of the solution of Reactive Red 120, a preliminary elucidation of the degradation mechanism