Zhixiang Ye

Adsorption intrinsic kinetics and isotherms of lead ions on steel slag.

Batch experiments were carried out to investigate the kinetics of adsorption of lead ions by steel slag on the basis of the external diffusion, intra-particle diffusion and adsorption reaction model (pseudo-first-order, pseudo-second-order). The results showed that the controlling step for the adsorption kinetics changed with the varying experimental parameters. When the particle size of steel slag was larger than 120 mesh, intra-particle diffusion of Pb(2+) was the controlling step, and when the initial concentration of Pb(2+) was less than 150 m gL(-1) or the shaking rate was lower than 150 rpm, external diffusion of Pb(2+) was promoted. Contrary to the former experimental conditions the adsorption reaction was the controlling step, and the adsorption followed second-order kinetics, with an adsorption rate constant of 13.26 g mg(-1)min(-1). The adsorption isotherm of Pb(2+) with steel slag followed the Langmuir model, with a correlation coefficient of 0.99.

Simulation Studies on Limestone Dissolution with Organic Acid Additives in Limestone-Based Flue Gas Desulfurization

The effects of organic acids on limestone dissolution rate were investigated by pH-stat method. The results showed that the dissolution rate of -60+80 mesh with 50 mmol/L acetic acid was the same as that of -300 mesh without organic acid. With the same concentration of acetic acid and benzoic acid, the former had stronger ability than the latter to increase the limestone dissolution. By increasing concentration of organic acid added, the granular limestone can be used as a desulfurizing reagent directly. Furthermore, the mechanism of organic acid promoting limestone dissolution was suggested.

2,4-Dichlorophenol Degradation by Heterogeneous Fenton Like Reaction Using carbon-Fe Catalysts

Catalytic degradation of simulated 2,4-dichlorophenol wastewater are investigated by using self-synthesized Fe/activated carbon (AC) catalysts and hydrogen peroxide oxidation agent. Effects of the most relevant operating conditions(pH, catalysts concentration, 2,4-dichlorophenol concentration, H 2 O 2 concentration and reaction temperature) were discussed. The results indicate that the degradation rate of 2,4-dichlorophenol (400 mg/L) reach 79.9% in the presence of Fe/AC(2g/L) and hydrogen peroxide (1%) at pH = 3 after 180 minutes under normal temperature and atmospheric pressure. Kinetic studies of the catalytic reaction showed that the degradation reaction of 2,4-dichlorophenol nearly follows the first-order reaction, the reaction constant and activity energy are 0.00626 mm -1 and 66.50 kJ/mol at 30degC, respectively.

Evolution of chemical composition of fogwater in winter in Chengdu, China

Two sampling sites representing the urban and suburban area of Chengdu, China were sampled and analyzed for selected chemicals to characterize the evolution of the chemical composition of fogwater. A trend of total organic carbon (TOC) > total nitrogen (TN) > total inorganic carbon (TIC) was observed for both sites. Variation of inorganic ions indicated that inorganic pollutants were not accumulated in the fog. Concentrations of n-alkanes (C11-C37) at the urban site ranged from 7.58 to 27.75 ng/mL while at the suburban site concentrations were 2.57-21.55 ng/mL. The highest concentration of n-alkanes was observed in the mature period of fog (393.12 ng/mL) which was more than ten times that in the fog formation period (27.83 ng/mL) and the fog dissipation period (14.87 ng/mL). Concentrations of Sigma15PAHs were in the range of 7.27-38.52 ng/mL at the urban site and 2.59-22.69 ng/mL at the suburban site. Contents of PAHs in the mature period of fog (27.15 ng/mL) > fog dissipation period (11.59 ng/mL) > fog formation period (6.42 ng/mL). Concentrations of dicarboxylic acids (C5-C9) ranged from 10.92 to 40.78 ng/mL, with glutaric acid (C5) as the dominant dicarboxylic acid. These data provide strong indications of the accumulation of certain organic chemicals of environmental concern in fog and fog water, and provide additional insights about processes in urban and suburban air acting on organic chemicals with similar physical chemical properties.

Study on Characteristics of TSP and Its Bounded Pollutants in the Vicinity of Shuangliu International Airport, China

Total suspended particulate (TSP) is the one of the major urban air pollutants in China which endangered the human health. Its pollution extent and characteristics attracted much attention. Study of many urban air pollution sources were reported such as coal-fired emissions, soil dust, industrial dust, vehicle exhausts, etc., but few study focus on an important source-variation exhausts. In this study, the building near Shuangliu airport was selected as the sampling site and the stadium stands in the campus of Chengdu University of Information Technology was selected as the control site. The intelligent high-volume TSP sampler was used to collect TSP from April 13, 2009 to April 16, 2009. Concentrations of TSP in the atmospheric were calculated and its bounded pollutants were studied. n-Alkanes and PAHs were determined by ultrasonic extraction- gas chromatography- mass spectrometry method. Results showed that at sampling site, the average concentration of TSP was 362.175µg /m3, ∑n-alkanes bound to TSP was 0.42~2.37 µg/m3, CPI value of 0.937-1.744, with average of 1.36 which suggested they were mainly from anthropogenic sources such as fossil fuel combustion. Contents of ∑15PAHs were 16.84~78.90 ng /m3 with much higher data in the nighttime than in the daytime. The main combustion-derived PAHs concentrations (COMPAHs) covered more than 90.0% of the total PAHs in TSP. These results suggested the contribution of aviation was one of the atmospheric pollution sources in the nearby area.

New Limestone-Gypsum Flue Gas Desulfuization Technology

A new wet FGD processes which SO2 was absorbed in the spray tower using granular limestone simultaneously adding acetic acid had been proposed. The main difference compared to conventional wet FGD process was to utilize granular limestone directly as a desulphurization reagent simultaneously adding acetic acid. Thus, the pulverizing of limestone, which causes power consumption, can be saved. Only using granular limestone¿210μm¿ directly as absorbent without acetic acid, SO2 removal efficiency and limestone utilization were too low respective 60.7% and 44%. Adding 10-30 mmol/L acetic acid, degree of desulphurization was increased to 95% and the limestone utilization was enhanced to 93.5%, comparison with fine limestone, the desulphurization efficiency and limestone utilization were respective 88% and 92.9% at the same operating conditions. Adding organic acid, buffer capacity of system was enhanced. And the influent factors such as the concentration of acetic acid, limestone slurry and SO2, residence time of flue gas were tested. The mechanism of acetic acid promoting SO2 absorption was suggested.

Characteristic of Saturated Hydrocarbons in Total Suspended Particulate from an Underground Garage

Total suspended particulates (TSP) were collected from March 16, 2009 to March 20, 2009 at an underground garage in Chengdu University of Information Technology. Concentrations of TSP and its saturated hydrocarbons and other molecular markers were analyzed to characterize the pollution of vehicles in underground garage. Concentrations of TSP were higher during the daytime(182.4-226.6 µg m-3) than the nighttimes(111.6-134.3 µg m-3). The ∑n-alkane ranged from C12 to C36 and daily concentration of n-alkanes at sampling site ranged from 261 to 551 ng m-3 with an average of 425 ng m-3. The Carbon preference index (CPI) values ranging from 1.103 to 1.324 for the underground garage, indicated the strong influence of anthropogenic sources(vehicular). Series of Hopanes and Steranes were observed in the TSP samples, which indicated a petroleum origin.

Development of a New Flow-Injection Chemiluminescence Method for the Determination of Sulfide

A new flow-injection chemiluminescence method for the determination of trace amounts of sulfide was developed. It is based on the enhancement of sulfide on the chemiluminescence reaction of calcein with potassium ferricyanide. The relationship between the increased chemiluminescence intensity and the concentration of sulfide is linear in the range of 3.0×10-8-2.0×10-6g/ml. The detection limit is 6.2×10-9 g/ml with the relative standard deviation 3.8% (n =11, 5.0×10-8g/ mLS2-). The method has been applied to the determination of sulfide in water sample with satisfactory results.

Screening a Novel Bioflocculant-Producing Strain B-28 and Its Use for Wastewater Treatment

A bioflocculant-producing bacterium, named B-28, was isolated from contaminative soils by gas oil wastewater and identified as Bacillus sp. according to its morphological, physiological, biochemical properties and the analysis of its 16S rDNA gene sequence. The effects of bioflocculant dosage on flocculating activity in kaolin suspension showed that more than 80% of flocculant activity was observed in the range of 0.5-2.0 ml crude fermentation liquid of strain B-28. And the flocculation activity of MBF-28 varies from approximately 80.3% to 93.5% in the temperature range of 20 to 65 oC. Moreover, FT-IR spectra showed hydroxyl, C-H, carbonyl, C-O-C groups were present in the MBF-28 molecule and the mainly effective composition of bioflocculant is polysaccharide with the total content of 73.48% (w/w).The wastewater treatment experiments results indicated that the MBF-28 was efficient for decolorization ratio of 82.44% and the removal rate for Cr6+ was 52.11%, respectively.