Advanced Materials Research Vols. 610-613

Abstract: In geological disposal of radioactive wastes, the study of Plutonium migration is very important for the safety evaluation of the repository. The forms of chemical components of Plutonium presence in aqueous solution that directly affect its migration behavior provide a basis for analog computation of the element. This paper uses PHREEQC, the geochemical model, for analog computation of forms of Plutonium presence in two types of groundwater, and analyzes the morphologies of the main elements and the influencing factors. The results show that the morphology of Plutonium is mainly controlled by the characteristics of the chemical composition of groundwater, while the PH value also has a great impact on the forms of Plutonium presence.

Abstract: Two efficient anthracene-degrading strains are isolated from pollution sludge collected from sewage treatment plant and identified by sequencing their 16S rDNA genes, one is Pseudomonas nitroreducens and the other is Bacillus sp.. The proper growth conditions of each bacterium was measured and presented for anthracene-degrading. The optimum growth condition is pH 7.5, 30°C. Biodegradation assays revealed that the degradation rates of two bacterial strains are 82.3% and 80.7% in 7 days. Respectively, the two bacteria had played important roles in the degradation of anthracene.

Abstract: Alumina microparticles were synthesized by sol-gel method with aluminum isopropoxide as raw material, octanol and acetonitrile as solvent. The influence of pH value and three kinds of dispersants on the alumina suspension stability were discussed in water system. We find that The optimal pH value range of application for alumina suspension is 4-5 or 10-11, which has the biggest absolute value of Zeta potential, and alumina suspension has a good dispersion when Span-20 used as dispersant.

Abstract: l-Hydroxychlordene is the major metabolite of organochlorine pesticide heptachlor in soil. In this study, the biotransformation of l-hydroxychlordene was performed with the white rot fungus Phlebia acanthocystis TMIC34875, which is capable of degrading heptachlor. As a result, 1-hydroxychlordene was degraded completely by the fungal treatment in pure cultures after 15 days of incubation. A large amount of epoxylation product1-hydroxy-2,3-epoxychlordene was detected as metabolites of 1-hydroxychlordene using GC/MS analysis. This fungus particularly can degrade 1-hydroxy-2,3-epoxychlordene to two trihydroxychlordene isomers through hydrolysis at epoxy ring. The results suggested that 1-hydroxychlordene was metabolized to hydrophilic products via 1-hydroxy-2,3-epoxychlordene by P. acanthocystis TMIC34875.

Abstract: Removal of vapor-phase elemental mercury (Hg⁰) over an activated coke (AC) and activated coke supported CuO catalyst (CuO/AC) were studied under N₂+HCl atmosphere. This paper describes the influences of CuO loading, reaction temperature, Hg⁰ concentration and space velocity on Hg⁰ removal over CuO/AC. It was found that CuO/AC had a higher Hg⁰ removal capability than that of AC, which can be attributed to the oxidation activity of CuO. The capability of CuO/AC for Hg⁰ removal increased with an increase of CuO loading (1-20 wt.%). The Hg⁰ removal capability was the highest at around 180 °C in the temperature range of 120-200 °C, which can be due to the co-effect of adsorption and oxidation. As Hg⁰ concentration and space velocity decreased, the Hg⁰ removal efficiency increased.

Abstract: TiO₂-based hybrid catalysts functioned by Keggin-type heteropolyacid, H₃PW₁₂O₄₀/ TiO₂, were prepared via one-pot co-condensation method in the presence of a triblock copolymer surfactant (F127). The materials were well characterized by FT-IR, UV-vis DRS spectroscopy methods, and X-ray diffraction analysis to confirm the structural integrity of the Keggin unit in the hybrid materials, to investigate correlation between TiO₂ matrix and H₃PW₁₂O₄₀. Phtocatalytic tests show the composite exhibits higher photocatalytic activity to decompose the Rhodamine B ( RhB ) than anatase TiO₂.

Abstract: The rice bran protein (RBP) was then hydrolyzed with various proteases (papain, flavorzyme, neutrase, protamex, and trypsin) to prepare antioxidant peptides. The rice bran protein hydrolysates (RBPH) were assessed using method of DPPH radical scavenging ability. Hydrolysate prepared with papain and flavorzyme (activity ratio 1:1) was found to have the highest antioxidant activity (IC50=6.778±0.21 mg/ml). This hydrolysate was purified using ultrafiltration, RBPH-III (Mw＜3KDa) had the highest DPPH and hydroxyl radical scavenging activity (IC50 value of 6.56±0.28, 5.43±0.22, respectively) and highest reducing power activity (1.02±0.18 at 4 mg/mL). Later, RBPH-III was fractionated by SP-SephadexC-25 cation-exchange column into six fractions (A–F), fraction F with the highest DPPH scavenging activity, was then separated by size exclusion chromatography on a SephadexG-25 into three major fractions (F1–F3). Fraction F2 exhibited the highest DPPH scavenging activity was choose to fractionate by reversed-phase high performance liquid chromatography (RP-HPLC), seven antioxidant peptides were isolated, The F2-5 peptide displayed the highest DPPH radical-scavenging activity (58.2±1.63%; at 250 μg/ml) among these peptides, the amino acids composition of F2-5 was determined, which might play an important role on its antioxidant activity. In addition, purified peptide did show remarkable inhibition rate on SGC-7901 cells proliferation, and it also revealed the dose-dependent relationship. The results of this study suggest that rice bran protein hydrolysates are good source of natural antioxidants.

Abstract: The ore assays 2.5g/t Au, 23.4% S and 56.6% Fe. This research enriched the gold by flotation, and recovered it by a chemical process. The obtained flotation concentrate contains 66.35%g/t gold and 37.06% S with recovery 96.14% and 96.42% respectively. A roasting process was conducted at 900-1000°C for 5.5hrs, followed by cyanide leaching of the residue. The gold leaching rate reaches 87.4% with an adsorption rate of 97.6%. Furthermore, the regrinding of the concentrate to 95% -0.18μm was conducted, and followed by cyanide leaching at pH11.5 for 12hrs. The results show the amount leached gold reaches 92.5% with an adsorption rate of 99.21%, which increases by 1.61% and 5.1% in comparison with the roasting-leaching process.

Abstract: A photo-electro-chemical (PEC) catalytic reactor with double compartments was designed. Benzoquinone in cathodal compartment was degradated effectively using these different cathodes and the maximum percent degradation was 66.1% using TiO₂/Ti thin film cathode fired by 600°C. There was higher concentration of H₂O₂ and ·OH on TiO₂/Ti thin film electrode fired by 600°C than others. Under the optimum condition of constant current at 3.5 mA, initial solution pH at 5.42, reaction time at 60 min, accumulative concentration of H₂O₂ was 0.35mg·L^-1 and ·OH steady state concentration= 2.19×10^-14 mol·L^-1.

Abstract: The potential effect of 1,4-dichlorobenzene(1,4-DCB) on Microbial Populations and enzyme activities was investigated in a flooded wetland soil. The results showed that the number of actinomycetes declined significantly after the treatment of 1,4-DCB at different concentrations, and the amout of bacteria and fungi were significantly decreased in soil samples treated with higher than 200 mg/Kg. 1,4-DCB at over the range of selected concentrations could completely inhibit urease activityin the first 28 days.1,4-DCB at the concentration lower than 100 mg/Kg dried soil stimulated the activity of catalase , while the others showed an inhibition during period of incubation. Results indicated that these two enzymes are sensitive to 1,4-DCB contamination.