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Bromate ion formation in dark chlorination and ultraviolet/chlorination processes for bromide-containing water

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Journal of Environmental Sciences 2008年第2期20卷 246-251页

作者： HUANG Xin gao naiyun DENG Yang State Key Laboratory of Pollution Control and Resource Reuse Tongji University Shanghai 200092 China Department of Construction Management and Civil Engineering Technology Georgia Southern University R O. Box 8047 Statesboro GA 30460-8047 USA

Bormate （BrO3^-） is a carcinogenic chemical produced in ozonation or chlorination of bromide-containing water. Although its formation in seawater with or without sunlight has been previously investigated, the formation of bromate in dilute solutions, particularly raw water for water treatment plant, is unknown. In this article, the results of bench scale tests to measure the formation rates of bromate formation in dilute solutions, including de-ionized water and raw water from Yangtze River, were presented in dark chlorination and ultraviolet （UV）/chlorination processes. And the effects of initial pH, initial concentration of NaOCl, and UV light intensity on bromate formation in UV/chlorination of the diluted solutions were investigated. Detectable bromate was formed in dark chlorination of the two water samples with a relatively slow production rate. Under routine disinfecting conditions, the amount of formed bromate is not likely to exceed the national standards （10 μg/L）. UV irradiation enhanced the decay of free chlorine, and, simultaneously, 6.6%-32% of Br^- was oxidized to BrO3^-. And the formation of bromate exhibited three stages： rapid stage, slow stage and plateau. Under the experimental conditions （pH = 4.41-11.07, CCl2= 1.23-4.50 mg/L）, low pH and high chlorine concentration favored the generation of bromate. High light intensity promoted the production rate of bromate, but decreased its total generation amount due to acceleration of chlorine decomposition.

关键词： bromate chlorination raw water Yangtze River ultraviolet (UV) irradiation

Characteristics and model studies for fluoride and arsenic adsorption on goethite

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Journal of Environmental Sciences 2010年第11期22卷 1689-1694页

作者： Yulin Tang Jianmin Wang naiyun gao State Key Laboratory of PoUution Control and Resources Reuse College of Environmental Science and Engineering Tongji University Shanghai 200092 China. Department of Civil Architectural & Environmental Engineering Missouri University of Science and Technology Rolla MO 65409 USA

Fluoride and arsenic are major anionic elements of concern in drinking water treatment. The effects of contact time, pH, surface loading and ionic strength on adsorption of fluoride and As（V） were investigated using batch methods. Adsorption of fluoride and As（V） onto goethite obeyed a pseudo second-order rate law. Through experimental data and adsorption kinetic analysis, the affinity of As（V） onto goethite was stronger than fluoride. Fluoride and As（V） uptake by goethite all decreased with pH increasing at the same surface loading; however, ionic strength had slight influence on their adsorption. A surface sites-species model was used to quantify the adsorption of fluoride and As（V） onto goethite as function of pH and surface loading. This model can satisfactorily predict their adsorption characteristics with several adsorption constants.

关键词： adsorption fluoride arsenic goethite

Perchlorate removal using granular activated carbon supported iron compounds: Synthesis, characterization and reactivity

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Journal of Environmental Sciences 2010年第11期22卷 1807-1813页

作者： Jianhong Xu naiyun gao Yulin Tang Yang Deng Minhao Sui State Key Laboratory of Pollution Control and Resource Resue Tongji University Shanghai 200092 China Jiangxi University of Science and Technology Ganzhou 341000 China Department of Earth and Environmental Studies Montclair State University Montclair New Jersey 07043 USA

Synthesis and use of the iron compounds supported on granular activated carbon （ICs/GAC） have shown significant environmental implications for perchlorate （ClO4^- ） removal. ICs/GAC was synthesized via hydrolyzing FeSO 4 ·7H2O on GAC, reduced by NaBH 4 solution in polyethylene glycol 6000 and ethanol solution, dried in vacuum condition and exposed to air. Synthesized ICs/GAC was characterized using transmission electron micrograph （TEM）, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy （XPS）. ICs/GAC was determined to be containing a large amount of FeOHSO 4 , Fe2O3 and a small amount of zero-valent iron （ZVI） nanoparticles according to TEM and XPS measurements. Batch static kinetic tests showed that 97% of ClO4^- was removed within 10 hr at 90°C and 86% of ClO4^- was removed within 12 hr at 25°C, at ICs/GAC dosage of 20 g/L. The experimental results also showed that FeOHSO 4 and Fe 2 O 3 nanoparticles have the function of perchlorate adsorption and play important roles in ClO4^- removal. The activation energy （E a ） was determined to be 9.56 kJ/mol.

关键词： perchlorate removal ICs /GAC activation energy synthesis

Photochemical degradation of typical halogenated herbicide 2,4-D in drinking water with UV/H_(2)O_(2)/micro-aeration

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Science China Chemistry 2009年第12期52卷 2351-2357页

作者： CHU WenHai gao naiyun LI Chong CUI Jing State Key Laboratory of Pollution Control and Resources Reuse Tongji UniversityShanghai 200092China Department of Civil and Structure Engineering Hong Kong Polytechnic UniversityHong KongChina

UV/H2O2/micro-aeration is a newly developed process based on UV/H2O2. Halogenated pesticide 2,4-dichlorophenoxyacetic acid (2,4-D) photochemical degradation in aqueous solution was studied under various solution conditions. The UV intensity,initial 2,4-D concentrations and solution temperature varied from 183.6 to 1048.7 μW·cm-2,from 59.2 to 300.0 μg·L-1 and from 15 to 30℃,respectively. The concentration of hydrogen peroxide (H2O2) and pH ranged from 0 to 50 mg·L-1 and 5 to 9,and different water quality solutions (tap water,distilled water and deionized water) were examined in this study. With initial concentration of about 100 μg·L-1,more than 95.6% of 2,4-D can be removed in 90 min at intensity of UV radiation of 843.9 μW·cm-2,H2O2 dosage of 20 mg·L-1,pH 7 and room temperature. The removal efficiency of 2,4-D by UV/H2O2/micro-aeration process is better than UV/H2O2 process. The photodecomposition of 2,4-D in aqueous solution follows pseudo-first-order kinetics. 2,4-D is greatly affected by UV irradation intensity,H2O2 dosage,initial 2,4-D concentration and water quality solutions,but it appears to be slightly influenced by pH and temperature. There is a linear relationship between rate constant k and UV intensity and initial H2O2 concentration,which indicates that higher removal capacity can be achieved by the improvement of these factors. Finally,a preliminary cost analysis reveals that UV/H2O2/micro-aeration process is more cost-effective than the UV/H2O2 process in the removal of 2,4-D from drinking water.

关键词： 2,4-dichlorophenoxyacetic acid endocrine disrupting chemicals photochemistry advanced oxidation processes pollution control cost analysis

Removal of phenol by powdered activated carbon adsorption

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Frontiers of Environmental Science & Engineering 2013年第2期7卷 158-165页

作者： Yan MA naiyun gao Wenhai CHU Cong LI State Key Laboratory of Pollution Control and Resource Reuse Tongji University Shanghai 200092 China Institute of Municipal Engineering Zhejiang University Hangzhou 310058 China

In this study, the adsorption performance of powdered activated carbon （PAC） on phenol was investi- gated in aqueous solutions. Batch adsorption studies were performed to evaluate the effects of various experimental parameters like PAC type, PAC dose, initial solution pH, temperature and pre-oxidation on the adsorption of phenol by PAC and establish the adsorption kinetics, thermo- dynamics and isothermal models. The results indicated that PAC adsorption is an effective method to remove phenol from water, and the effects of all the five factors on adsorption of phenol were significant. The adsorption rate of phenol by PAC was rapid, and more than 80% phenol could be absorbed by PAC within the initial 10 min. The adsorption process can be well described by pseudo- second-order adsorption kinetic model with rate constant amounted to 0.0313, 0.0305 and 0.0241 mg.μg .min -1 with coal, coconut shell and bamboo charcoal. The equilibrium data of phenol absorbed onto PAC were analyzed by Langmuir, Freundlich and Tempkin adsorp- tion isotherms and Freundlich adsorption isotherm model gave the best correlation with the experimental data. Thermodynamic parameters such as the standard Gibbs free energy （△G0）, enthalpy （△H0） and entropy （△S0） obtained in this study indicated that the adsorption of phenol by PAC is spontaneous, exothermic and entropy decreasing.

关键词： phenol powdered activated carbon adsorption kinetics isotherms

Characterization of typical taste and odor compounds formed by Microcystis aeruginosa

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Journal of Environmental Sciences 2013年第8期25卷 1539-1548页

作者： Kejia Zhang Tsair Fuh Lin Tuqiao Zhang Cong Li naiyun gao College of Civil Engineering and Architecture Zhejiang University Department of Environmental Engineering National Cheng Kung University State Key Laboratory of Pollution Control and Resource Reuse Tongji University

Production and characteristics of typical taste and odor （T＆O） compounds by Microcystis aeruginosa were investigated. A few terpenoid chemicals, including 2-MIB, β-cyclocitral, and β-ionone, and a few sulfur compounds, such as dimethyl sulfide and dimethyl trisulfide, were detected. β-Cyclocitral and β-carotene concentrations were observed to be relevant to the growth phases of Microcystis. During the stable growth phase, 41-865 fg/cell of β-cyclocitral were found in the laboratory culture. β-Cyclocitral concentrations correlated closely with β-carotene concentrations, with the correlation coefficient R2 = 0.96, as it is formed from the cleavage reaction of β-carotene. For dead cell cases, a high concentration of dimethyl trisulfide was detected at 3.48-6.37 fg/cell. Four T＆O compounds, including β-cyclocitral, β-ionone, heptanal and dimethyl trisulfide, were tested and found to be able to inhibit and damage Microcystis cells to varying degrees. Among these chemicals, β-cyclocitral has the strongest ability to quickly rupture cells.

关键词： Microcystis aeruginosa T&O compounds β-cyclocitral algae-lytic effect

Formation of THMs and HANs during bromination of Microcystis aeruginosa

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Journal of Environmental Sciences 2013年第9期25卷 1795-1799页

作者： Yunzhu Pu Lingzhao Kong Xin Huang Guoji Ding naiyun gao School of Environmental and Chemical Engineering Shanghai University Qingdao Institute of Bioenergy and Bioprocess Technology Chinese Academy of Sciences State Key Laboratory of Pollution Control and Resource Reuse Tongji University

Bromine-contained disinfectants and biocides are widely used in swimming pools, recreational waters and cooling towers. The objective of this study was to evaluate the formation of thrihalomethanes （THMs） and haloacetonitriles （HANs） and their cytotoxicity in algae solutions during free bromine disinfection. Disinfection by-products formation potential experiments were conducted using model solutions containing 7 mg/L （as total organic carbon） Microcystis aeruginosa cells. Effects of free bromine dosage, pH and ammonia were investigated. The results showed that brominated disinfection by-products were the major products when free bromine was applied. The total THMs formed during bromination was much as that formed during chlorination, whereas HANs were elevated by using bromination instead of chlorination. Dibromoacetonitrice （C2H2NBr2 ） and bromoform （CHBr3 ） were the only detected species during free bromine disinfection. The production of C2H2NBr2 and CHBr 3 increased with disinfectant dosage but decreased with dosing ammonia. CHBr3 increased with the pH changing from 5 to 9. However, C2H2NBr2 achieved the highest production at neutral pH, which was due to a joint effect of variation in hydrolysis rate and free bromine reactivity. The hydrolysis of C2H2NBr2 was base-catalytic and nearly unaffected by disinfectant. Finally, estimation of cytotoxicity of the disinfected algae solutions showed that HANs formation was responsible for the majority of toxicity. Considering its highest toxicity among the measured disinfection by-products, the elevated C2H2NBr2 should be considered when using bromine-related algaecide.

关键词： bromine Microcystis aeruginosa disinfection by-products

Adsorption of humic acid from aqueous solution on bilayer hexadecyltrimethyl ammonium bromide-modified zeolite

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Frontiers of Environmental Science & Engineering 2011年第1期5卷 65-75页

作者： Yanhui ZHAN Jianwei LIN Yanling QIU naiyun gao Zhiliang ZHU State Key Laboratory of Pollution Control and Resource Reuse Tongji UniversityShanghai 200092China College of Marine Science Shanghai Ocean UniversityShanghai 201306China

Surfactant-modified natural zeolites(SMNZ)with different coverage types were prepared by loading hexadecyltrimethyl ammonium bromide(HTAB)onto the surface of a natural *** adsorption behavior of humic acid(HA)on SMNZ was *** indicate that the adsorbent SMNZ exhibited a higher affinity toward HA than the natural *** removal efficiency by SMNZ increased with HTAB *** Ca2+in solution favored HA adsorption onto *** capacity decreased with an increasing solution *** typical SMNZ with bilayer HTAB coverage,HA adsorption process is well described by a pseudo-second-order kinetic *** experimental isotherm data fitted well with the Langmuir *** maximum HA adsorption capacities for SMNZ with bilayer HTAB coverage at pH 5.5 and 7.5 were 63 and 41 mg·g^(-1),respectively.E2/E3(absorbance at 250 nm to that at 365 nm)and E4/E6(absorbance at 465 nm to that at 665 nm)ratios of the residual HA in solution were lower than that of the original HA *** indicates that the HA fractions with high polar functional groups,low molecular weight(MW),and aromaticity had a stronger tendency for adsorption onto SMNZ with bilayer HTAB *** show that HTABmodified natural zeolite is a promising adsorbent for removal of HA from aqueous solution.

关键词： bilayer surfactant-modified zeolite hexadecyltrimethyl ammonium bromide(HTAB) adsorption humic acid(HA)

Modeling the aqueous reaction kinetics of estriol with ferrate

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Frontiers of Chemical Science and Engineering 2009年第1期3卷 39-45页

作者： Cong LI naiyun gao State Key Laboratory of Pollution Control and Resource Reuse Tongji UniversityShanghai 200092China

In this study the aqueous oxidation kinetics of estriol(E3)by potassium ferrate(K_(2)FeO_(4)),a chemical for its strong oxidizing power and for producing a coagulant from its reduced state(***(III)),was evaluated in the range of pH 8–12 with different molar ratios of the *** the degree of Fe(VI)protonation varies with the solution pH,it was found that aﬁrst order model was not suitable to describe the oxidation *** paper describes a theoretical representation that closely models the reaction kinetics of E3 and *** this modeling,the reaction rates of HFeO_(4)^(-) and FeO_(4)^(2-) with E3 have been *** results show that the reactivity of HFeO–with dissociated and undissociated E3 is greater than that4 of FeO_(4)^(2-),and that E3 is more reactive in its dissociated state.

关键词： ferrate estriol endocrine disruptor kinetics oxidation