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Surface reaction of Bacillus cereus biomass and its biosorption for lead and copper ions

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Journal of Environmental Sciences 2007年第4期19卷 403-408页

作者： PAN Jian-hua LIU Rui-xia tang hong-xiao State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China.

In this study, the surface chemical functional groups of Bacillus cereus biomass were identified by Fourier transform infrared （FTIR） analytical technique. It had been shown that the B. cereus cells mainly contained carboxyl, hydroxyl, phosphate, amino and amide functional groups. The potentiometric titration was conducted to explain the surface acid-base properties of aqueous B. cereus biomass. The computer program FITEQL 4.0 was used to perform the model calculations. The optimization results indicated that three sitesthree pKas model, which assumed the cell surface to have three distinct types of surface organic functional groups based on the IR analysis results, simulated the experimental results very well. Moreover, batch adsorption experiments were performed to investigate biosorption behavior of Cu（Ⅱ） and Pb（Ⅱ） ions onto the biomass. Obviously, the adsorption equilibrium data for the two ions were reasonably described by typical Langmuir isotherm.

关键词： Bacillus cereus biosorption Fourier transform infrared (FTIR) acid-base characteristic heavy metals

Effects of pre-ozonation on organic matter removal by coagulation with IPF-PACl

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Journal of Environmental Sciences 2006年第3期18卷 453-458页

作者： LIU Hai-long WANG Dong-sheng SHI Bao-you WANG Min tang hong-xiao State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China School of Environmental Science and Resources Shanxi University Taiyuan 030002 China School of Water Resources and Environmental Sciences China University of Geosciences Beijing 100083 China

Ozone plays an important role as a disinfectant and oxidant in potable water treatment practice and is increasingly being used as a pre-oxidant before coagulation. The purpose of this study is to obtain insight into the mechanisms that are operative in pre-ozonized coagulation. Effects ofpre-ozonation on organic matter removal during coagulation with IPF-PAC1 were investigated by using PDA （photometric disperse analysis）, apparent molecular weight distribution and chemical fractionation. The dynamic formation of flocs during coagulation process was detected. Changes of aquatic organic matter （AOM） structure resulted from the influence of pre-ozonation were evaluated. Results show that dosage of O3 and characteristics of AOM are two of the major factors influencing the performance of O3 on coagulation. No significant coagulation-aid effect of O3 was observed for all experiments using either A1C13 or PAC1. On the contrary, with the application of pre-ozonation, the coagulation efficiency of A1C13 was significantly deteriorated, reflected by the retardation of floc formation, and the removal decreases of turbidity, DOC, and UV254. However, if PACl was used instead of AlCl3, the adverse effects of pre-ozonation were mitigated obviously, particularly when the O3 dosage was less than 0.69 （mg O3/mg TOC）. The difference between removals of UV254, and DOC indicated that pre-ozonation greatly changed the molecular structure of AOM, but its capability of mineralization was not remarkable. Only 5% or so DOC was removed by pre-ozonation at 0.6--0.8 mg/L alone. Fractionation results showed that the organic products of pre-ozonation exhibited lower molecular weight and more hydrophilicity, which impaired the removal of DOC in the following coagulation process.

关键词： natural organic matter (NOM) fractionation pre-ozonation PACl coagulation

Al(III) speciation distribution and transformation in high concentration PACl solutions

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Journal of Environmental Sciences 2006年第5期18卷 872-879页

作者： HUANG Li tang hong-xiao WANG Dong-sheng WANG Shui-feng DENG Zai-jun State Key Lab of Environmental Aqueous Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Analytical and Testing Center Beijing Normal University Beijing 100875 China

Effects of Al（Ⅲ） concentration and pH on the speciation of Al（Ⅲ） in polyaluminum chloride （PACl） solutions especially on the Al13 fraction were investigated. A series of PACl samples were prepared over the range of Al（Ⅲ） concentration from 0.01 to 2.0 mol/L with the B （OH/Al ratio） value from 1.0 to 2.5 by forced hydrolysis of AICl3. The samples were characterized by ferron assay, pH and 27^Al NMR. It was shown that the Al（Ⅲ） concentration had a dramatic effect on the hydrolysis processes and the species distribution of PACl was in relate to the decrease of pH. The fraction of Al species, Alb （or Al13） decreased and Al0 increased with increase of total Al（Ⅲ） concentration. Under the condition of Al（Ⅲ） 2.0 reel/L, B = 2.5, the pH value was 2.73 and no Al13 could be detected. During diluting and aging, the species distribution evoIved. The Al13 could then be detected again and the amounts increased with time. If the diluted samples were concentrated by freeze dry at -35℃ or heating at 80℃, the pH value and Al13 content would decrease with the increased concentration. It demonstrated that the key factor for formation of Al13 in concentrated PACl was pH value.

关键词： PACl Al13 B value pH speciation

MOVPE growth of InAs quantum dots for mid-IR applications

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中国有色金属学会会刊：英文版 2006年第B01期16卷 25-28页

作者： tang xiao-hong YIN Zong-you DU An-yan ZHAO Jing-hua DENY S Photonics Research Center School of Electrical and Electronic Engineering Nanyang Technological University 639798 Singapore Institute of Microelectronics 11 Science Park Road 117685 Singapore

InAs quantum dots (QDs) grown on InxGa1-xAs/InP matrix by low pressure metal organic vapor phase epitaxy (LP-MOVPE) in nitrogen ambient were studied. Formation of the InAs QDs with different growth conditions was investigated. To improve the dot size uniformity, a two-step growth method was used and investigated. It is found that morphology of the InAs QDs formed on such InxGa1-xAs/InP matrix is very sensitive to the growth conditions. InAs QDs with high density of 1.3×1010 cm?2 are grown by using S-K growth method with fast growth rate. Using the two-step growth method, the InAs QDs size uniformity improves by 63% and 110% compared that of the dots grown by ordinary S-K method and ALE method, respectively. Narrow photoluminescence (PL) emission spectrum of the QDs grown by using the two-step growth method is received. FWHM of the PL curve is measured at 26 meV and the peak emission wavelength is larger than 2.3 μm at 77 K.

关键词：砷化铟量子点 MOVPE 晶体生长中红外应用

Removal of natural organic matter in a typical south-China source water during enhanced coagulation with IPF-PACl

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Journal of Environmental Sciences 2005年第6期17卷 1014-1017页

作者： LIU Hai-long WANG Dong-sheng XIA Zhong-huan tang hong-xiao ZHANG Jin- song State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Institute of Environment and Resource Shanxi University Taiyuan 030002 China Shenzhen Water Group Co. Ltd. Shenzhen 518031 China

Systematic investigation on enhancing removal of natural organic matter （NOM） using inorganic polymer flocculant （IPF）, polyaluminum chloride（PACI） and polyacrylamide（PAM） was performed in a typical south-China source water. Enhanced coagulation and applying polymer flocculant-aid were compared through jar tests and pilot tests. Raw water and settled water were characterized and fractionated by resin adsorption. The results show that DOC composes major part of TOC. The DOC distribution keeps relatively stable all around the year with typical high amounts of the hydrophilic matter around 50%. The distribution between HoB, HoA and HoN varies and undergoes fluctuation with the year round. During the summer season, the HoN becomes gradually the major part in hydrophobic parts. PACI with the species being tailor-made shows little pH effect during coagulation. The enhanced coagulation dosage for PACI could be 4.5 mg/L for the typical source water. The highest TOC removal achieved 31%. To be economically, 3 mg/L dose is the optimum dosage. Although hydrophilic fractions of NOM of both treatment strategies are removed about 30%, NOM causing UV254 absorbance were well removed（about 90%）. Hydrophobic bases and acids fractions are much more removed under enhanced conditions. The hydrophilic fraction could be better removed using PAM, the polymer coagulant aid.

关键词： enhanced coagulation PACI PAM NOM fractionation

Transformations of particles, metal elements and natural organic matter in different water treatment processes

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Journal of Environmental Sciences 2007年第3期19卷 271-277页

作者： YAN Ming-quan WANG Dong-sheng SHI Bao-you WEI Qun-shan QU Jiu-hui tang hong-xiao State Key Laboratory of Environmental Aquatic Chemistry Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China

Characterizing natural organic matter （NOM）, particles and elements in different water treatment processes can give a useful information to optimize water treatment operations. In this article, transformations of particles, metal elements and NOM in a pilot-scale water treatment plant were investigated by laser light granularity system, particle counter, glass-fiber membrane filtration, inductively coupled plasma-optical emission spectroscopy, ultra filtration and resin absorbents fractionation. The results showed that particles, NOM and trihalomethane formation precursors were removed synergistically by sequential treatment of different processes. Preozonation markedly changed the polarity and molecular weight of NOM, and it could be conducive to the following coagulation process through destabilizing particles and colloids; mid-ozonation enhanced the subsequent granular activated carbon （GAC） filtration process by decreasing molecular weight of organic matters. Coagulation-flotation and GAC were more efficient in removing fixed suspended solids and larger particles; while sand-filtration was more efficient in removing volatile suspended solids and smaller particles. Flotation performed better than sedimentation in terms of particle and NOM removal. The type of coagulant could greatly affect the performance of coagulation-flotation. Pre-hydrolyzed composite coagulant （HPAC） was superior to FeCl3 concerning the removals of hydrophobic dissolved organic carbon and volatile suspended solids. The leakages of flocs from sand-filtration and microorganisms from GAC should be mitigated to ensure the reliability of the whole treatment system.

关键词： flotation fixed suspended solid trihalomethane formation potential ultra filtration resin absorbent fractionation

Effect of Tillage System on Distribution of Aggregates and Organic Carbon in a Hydragric Anthrosol

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Pedosphere 2008年第5期18卷 574-581页

作者： GAO Ming LUO You-Jin WANG Zi-Fang tang xiao-hong WEI Chao-Fu College of Resources and Environment Southwest University Chongqing 400716 （China）.

The effect of different tillage systems on the size distribution of aggregates and organic carbon distribution and storage in different size aggregates in a Hydragric Anthrosol were studied in a long-term experiment in Chongqing,China. The experiment included three tillage treatments:conventional tillage with rotation of rice and winter fallow(CT-r) system,no-till and ridge culture with rotation of rice and rape(RT-rr) system,and conventional tillage with rotation of rice and rape(CT-rr) system. The results showed that the aggregates 0.02-0.25 mm in diameter accounted for the largest portion in each soil layer under all treatments. Compared with the CT-r system,in the 0-10 cm layer,the amount of aggregates > 0.02 mm was larger under the RT-rr system,but smaller under the CT-rr system. In the 0-20 cm layer,the organic carbon content of all fractions of aggregates was the highest under the RT-rr system and lowest under the CT-rr system. The total organic carbon content showed a positive linear relationship with the amount of aggregates with diameter ranging from 0.25 to 2 mm. The storage of organic carbon in all fractions of aggregates under the RT-rr system was higher than that under the CT-r system in the 0-20 cm layer,but in the 0-60 cm soil layer,there was no distinct difference. Under the CT-rr system,the storage of organic carbon in all fractions of aggregates was lower than that under the CT-r system;most of the newly lost organic carbon was from the aggregates 0.002-0.02 and 0.02-0.25 mm in diameter.

关键词： aggregates Hydragric Anthrosol organic carbon tillage system

Apparent Kinetics for Electrosynthesis Process of Chromic Acid

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Chemical Research in Chinese Universities 2009年第4期25卷 532-536页

作者： LI Cheng-wei WANG Fu-an QI Tao WANG Rui-lin tang xiao-hong ZHANG Yong-qiang Department of Chemistry Henan institute of Education Zhengzhou 450014 P. R. China College of Chemical Engineering Zhengzhou University Zhengzhou 450002 P. R. China Institute of Process Engineering Chinese Academy of Sciences Beijing 100080 P. R. China

A new green technique for producing chromic acid via an electrosynthesis method was *** kinetic experiments were carried out on the direct electrosynthesis reaction of chromic acid from sodium dichromate in a self-made electrosynthesis reactor with a multiple-unit metal oxides combination anode,a stainless steel cathode,and a reinforcing combination Nafion 324 cation exchange *** apparent kinetic data were experimentally measured at different reaction time under different reaction conditions by relating many essential cell processes and their interaction,as well as their synergistic effect to the whole electrochemical synthesis *** results show that the electrosynthesis reaction process follows a quasi-first-order reaction kinetic *** apparent kinetic model of the electrosynthesis reaction was established,and kinetic parameters were calculated.

关键词： Apparent kinetics Chromic acid Electrosynthesis method Kinetic model

Developing sediment quality criteria for heavy metal pollution in the Le An River with equilibrium partitioning approach

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Journal of Environmental Sciences 1998年第4期10卷 16-21页

作者： Liu Wen xin, tang hong xiao Research Center for Eco Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China

Equilibrium partitioning(EqP) approach was selected to establish the sediment quality criteria(SQC) in the Le An River near Dexing Copper Mine. Both freshwater quality criteria (WQC) for some heavy metals regulated by USEPA and national quality standards of surface water recommended by CNEPA were used as protective levels of aquatic organisms in this study. Meanwhile, the partitioning coefficients were derived directly from measured data. Comparison between SQC in this region and concentrations of contaminants in situ clearly indicated the distribution characteristics of metal contamination along the river. And the results also illustrated that measures of some metals exceeded their SQC levels in different degree, especially Cu.

关键词： sediment quality criteria equilibrium partitioning Le An River heavy metal pollution.