Shengyu Liu

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.

Kinetic models for the adsorption of lead ions by 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, intraparticle diffusion and adsorption reaction model (pseudo-first-order, pseudo-second-order). The results showed that the controlling step for the adsorption kinetics changed with experimental parameters varied. When the particle size of steel slag was larger than 120 mesh, intraparticle diffusion of Pb2+ was the controlling step; when the initial concentration of Pb2+ was less than 150 mg L—1 or the shaking rate was lower than 150 rpm, external diffusion of Pb2+ 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 Pb2+ 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.

Adsorption Behaviors of Heavy Metal Ions by Steel Slag-An Industrial Solidwaste

Batch experiments were carried out to investigate heavy metal ions adsorption properties of steel slag, the results showed that steel slag could be used as an effective adsorbent to removal heavy metals such as Cr 3+ ,Cu 2+ ,Pb 2+ and Zn 2+ from the aqueous solution. For the heavy metal Cr 3+ , the removal yield increased with increasing contact time and reached the equilibrium state within lh; The removal of Cr 3+ increased from 44% to 99% at the rang of steel slag particle size from 2.5 mesh to 80 mesh, but go on decreasing the steel slag size, the removal of Cr 3+ did not almost change; The adsorption of Pb 2+ was not affected by pH value from 1.3 to 7.5, the removal percentages were all above 99%; at the same experimental conditions, the adsorption capacity of steel slag for mixed system decreased in the order of Cr 3+ > Zn 2+ > Cu 2+ > Pb 2+ , and comparing to the single metal ion system, the adsorption capacities all decreased, respectively.

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.

Hydrothermal Synthesis and Catalytic Activity of CeZrAl Oxide-Supported Pd for the Purification of Gasohol Exhaust

CeZrAl oxides (CZA) used as the support of Pd catalyst for purification of gasohol exhausts were synthesized by hydrothermal and coprecipitation method. CZA samples were characterized by N2 adsorption–desorption, XRD, H2–TPR, oxygen pulse adsorption, and XPS. The results show that the interactions between Pd and CZA with hydrothermal treatment lead to charge transfer from Pd species to Ce, which results in the presence of defect CeOx and more lattice oxygen in the catalyst. Catalytic tests demonstrate that hydrothermal treatment of CZA decreases the light-off temperature of propane, carbon monoxide, and ethanol by 50, 15, and 59°C, respectively.

Kinetics of acetic acid-enhanced coarse limestone dissolution

The dissolution kinetics of limestone with organic acid additives was studied by pH-stat method. The results showed that the control step of limestone dissolution was changed with pH changing. At same time, the particle size of limestone was an important effect on its dissolution control step too. Enhancement coefficient of limestone dissolution added acetic acid was the function of pH and concentration of acetic acid. By applying the shrinking core model a kinetic model for the limestone dissolution process was fitted to experimental results, which was function of concentration of acetic acid, particle of limestone and pH value and temperature.

Simultaneous Denitrification by Complex Adsorption in Bubbling Reactor

The process and mechanism of NO and SO2 adsorption by [Co(en)3]2+ in bubble reactor were investigated. Under the experimental conditions that temperature was 20°C, pH value was 13.0, and concentration of [Co(en)3]2+ was 0.025mol/L, 1g CaO, NH3·H2O, NaOH and carbide slag were added respectively, the solution added NH3·H2O and carbide slag gave a high NO removal rate, and after continuous absorption for 60min the NO removal rate was maintained above 93.5%, Adding NaOH and NH3·H2O, the removal of SO2 were high.

Dissolution Characteristics of Limestone with Organic Acid

The effects of organic acids on limestone dissolution rate were investigated by pH-stat method. The results showed that the concentration of organic acid, the acidity of limestone slurry and the kind of organic acid were the main factor to increase limestone dissolution rate. By increasing concentration of organic acid added, the granular limestone can be used as a desulfurizing reagent. Thus, the energy of the pulverizing limestone can be reduced. Furthermore, the mechanism of organic acid promoting limestone dissolution was suggested.