Yijin Yang

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.

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.

Adsorption of Pb (II), Cu(II) and Cr(VI) from Synthetic Solution Using Pyrolusite- Intermingled Sewage Sludge Adsorbent

A new adsorbent was developed from municipal sewage sludge (SS) combined with 5-20% pyrolusite of the weight of SS carbon, and using ZnCl2 as chemical activation reagent. Characterized by N2-BET methods and SEM, the result showed that the surface area of the new adsorbent was increased to 354.198 m2/g compared with that of the unmi- xed sludge activated carbon 232.526 m2/gand total pore and micropore volume were increased. The effect of various parameters on adsorption process including contact time, solution pH, amount of adsorbent and initial concentration of metal ions were studied at room temperature to optimize the conditions for maximum adsorption. The results showed that the adsorption capacities of Pb(II) ,Cu(II) and Cr (Ⅵ)by the new adsorbent could reach 13.31mg/g, 15.73 mg/g and 17.88 mg/g respectively, while the initial Pb(II) , Cu (II) and Cr (Ⅵ)concentration was 50 mg/L at the liquid /solid ratio of 1 g/L. Kinetic results were shown that the new adsorbent was better efficient materials for removing the Pb(II) ,Cu(II) and Cr (Ⅵ) from the synthetic solution, and the preferential order was equal: Pb(II) > Cu(II) > Cr (Ⅵ).

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.