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Preparation of cross-linked magnetic chitosan with quaternary ammonium and its application for cr(Ⅵ) and P(Ⅴ) removal

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Journal of Environmental Sciences 2014年第12期26卷 2379-2386页

作者： Wei Yao Pinhua Rao Irene M.C.Lo Wenqi Zhang Wenrui Zheng School of Chemistry and Chemical Engineering Shanghai University of Engineering Science Department of Civil and Environmental Engineering The Hong Kong University of Science and Technology

Pollutants that exist in anionic species are issues of concern in water treatment. Compared to cationic pollutants, the removal of anionic pollutants by adsorption is more difficult because most adsorbents carry predominantly negative charges in neutral and alkaline environments. In this study, a cross-linked chitosan derivative with quaternary ammonium and magnetic properties（QM-chitosan） was prepared and employed to remove chromium（vi） and phosphorus（V）（Cr（VI） and P（V）） from aqueous environments. The QM-chitosan was characterized by Fourier transform infrared spectrometry（FT-IR）,thermogravimetric analysis（TGA）, energy dispersive X-ray（SEM-EDX） and zeta potential.Batch experiments show that QM-chitosan can effectively remove Cr（VI） and P（V）, and the main mechanism was believed to be electrostatic interaction. A pseudosecond-order model was fitted to describe the kinetic processes of Cr（VI） and P（V） removal. The adsorption isotherms of both Cr（VI） and P（V） on the QM-chitosan were well fitted by the Langmuir isotherm equation. The saturated adsorption capacity of P（V）（2.783 mmol/g） was found to be higher than that of Cr（VI）（2.323 mmol/g）, resulting from the size of the H2PO-4ions being smaller than that of the Hcr O-4ions. However, the theoretical calculation and experimental results showed that QM-chitosan had a stronger affinity for Cr（VI） than P（V）. The adsorption–desorption of the QM-chitosan was evaluated, and high regeneration rates were demonstrated.

关键词： Magnetic chitosan Quaternary ammonium Cr（VI） P（V） Adsorption

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Formation of willow leaf-like structures composed of NH2-MIL68（In） on a multifunctional multiwalled carbon nanotube backbone for enhanced photocatalytic reduction of Cr（VI）

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Nano Research 2017年第10期10卷 3543-3556页

作者： Yunhong Pi Xiyi Li Qibin Xia Junliang Wu Zhong Li Yingwei Li Jing Xiao School of Chemistry and Chemical Engineering South China University of Technology Guangzhou 510640 China Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control South China University of Technology Guangzhou 510640 China

Efficient separation and transfer of photogenerated electron/hole as well as enhanced visible light absorption play essential roles in photocatalytic reactions. To promote the photocatalytic reduction of Cr（VI）, a toxic heavy metal ion, multiwalled carbon nanotube （MWCNT） was introduced as an electron acceptor into NH2-MIL-68（In）. This led to the growth of a willow leaf-like metal-organic framework （MOF） on an MWCNT backbone forming MWCNT/NH2-MIL-68（In）（PL-1）, which showed a highly efficient transfer of photogenerated carriers. Moreover, MWCNT incorporation introduced more mesopores for Cr（VI） diffusion and enhanced the visible light adsorption without lowering the conduction band position. As a result, the photocatalytic kinetic constant of PL-1 was found to be almost three times higher than that of the parent NH2-MIL-68（In）. Thus, growing MOFs on MWCNTs provides a facile and promising solution for effective remediation of environmental pollution by utilizing solar energy. This work provides the first example of using MWCNT/MOF composites for photocatalytic reactions.

关键词： NH2-MIL-68（In） multiwalled carbon nanotube （MWCNT） photocatalytic reduction Cr（VI）

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Removal of hexavalent chromium from contaminated waters by ultrasound-assisted aqueous solution ball milling

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Journal of Environmental Sciences 2017年第2期29卷 276-283页

作者： Lin Chen Zhenhua Chen Ding Chen Wei Xiong College of Materials Science and Engineering Hunan UniversityChangsha 410082China

Batch mode experiments were conducted to study the removal of hexavalent chromium（cr（Ⅵ）） from aqueous solutions using ultrasound-assisted aqueous solution ball milling.The results show that the reduction rate of cr（Ⅵ） by ultrasound-assisted aqueous solution ball milling was significantly faster than that by ball milling or ultrasound treatment alone,and an initial cr（Ⅵ） concentration of 166 mg/L could be decreased to 0.35 mg/L at 120 min.The decisive factors, including initial concentration of cr（Ⅵ）, p H value, ultrasonic frequency and filling gas, were studied. It was found that the optimal ultrasonic frequency for ultrasound-assisted aqueous solution ball milling device was 20 k Hz, and the rate of cr（Ⅵ）reduction as a function of filling gas followed the order： Ar 〉 air 〉 N2〉 O2. Samples were characterized by X-ray diffraction, fluorescence measurements, atomic absorption and the diphenylcarbazide colorimetric method. The cr（Ⅵ） transformed into a precipitate that could be removed from the contaminated water, after which the water could be reused.

关键词： Cr（VI） Ultrasound wave Ball milling Hydroxyl radicals

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Polyphenylene sulfide based anion exchange fiber:Synthesis,characterization and adsorption of cr(vi)

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Journal of Environmental Sciences 2012年第8期24卷 1433-1438页

作者： Jiajia Huang Xin Zhang Lingling Bai Siguo Yuan College of Chemical Engineering and Energy Zhengzhou UniversityZhengzhou 450001China

A fibrous strong base anion exchanger （QAPPS） was prepared for the first time via chloromethylation and quaternary amination reaction of polyphenylene sulfide fiber （PPS）, and its physical-chemical structure and adsorption behavior for Cr（VI） were characterized by FT- IR, Energy Dispersive Spectrometry, TG-DTG, elemental analysis and batch adsorptive technique, respectively. The novel fibrous adsorbent could effectively adsorb Cr（VI） over the pH range 1-12, the maximum adsorption capacity was 166.39 mg/g at pH 3.5, and the adsorption behavior could be described well by Langmuir isotherm equation model. The adsorption kinetics was studied using pseudo first-order and pseudo second-order models, and the 4/2 and equilibrium adsorption time were 5 and 20 min respectively when initial Cr（VI） concentration was 100 mg/L. The saturated fibers could be regenerated rapidly by a mixed solution of 0.5 mol/L NaOH and 0.5 mol/L NaCl, and the adsorption capacity was well maintained after six adsorption-desorption cycles.

关键词： strong base anion exchanger polyphenylene sulfide fiber Cr（VI） adsorption

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Adsorption of cr(Ⅵ) in wastewater using magnetic multi-wall carbon nanotubes

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Water Science and Engineering 2015年第3期8卷 226-232页

作者： Zhuo-nan Huang Xiao-ling Wang De-suo Yang Key Laboratory for Phytochemistry of Shaanxi Province Baoji University of Arts and Sciences College of Chemistry and Chemical Engineering Baoji University of Arts and Sciences

Magnetic multi-wall carbon nanotubes were prepared with wet chemical treatments and characterized by a transmission electron microscope （TEM） and X-ray diffraction （XRD）. They were used as adsorbents for the removal of Cr（VI） in aqueous solutions. The effects of adsorbent dosage, the concentration of Cr（VI） in aqueous solution, temperature, and pH value on the removal efficiency were studied. Results showed that the adsorption capacity of the magnetic multi-wall carbon nanotubes increased with the initial Cr（VI） concentration, but decreased with the increase of adsorbent dosage. The adsorption amount increased with contact time. The adsorption kinetics were best represented by the pseudo second-order kinetic model, and the adsorption isotherms indicated that the Langmuir model better reflected the adsorption process. The ob- tained calculation results for the Gibbs free energy revealed that the adsorption was a spontaneous and endothermic process. The enthalpy deviation was 3.835 kJ.mol 1. The magnetic multi-wall carbon nanotubes showed significant potential for application in adsorption of heavy metal ions.

关键词： Magnetic multi-wall carbon nanotubes Cr（VI） Adsorption Kinetics Thermodynamics

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The biosorption of Cr（VI） ions by dried biomass obtained from a chromium-resistant bacterium

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Frontiers of Chemical Science and Engineering 2014年第4期8卷 454-464页

作者： Paul Fabrice NGUEMA Zejiao LUO Jingjing LIAN State Key Laboratory of Biogeology and Environmental Geology Ministry of Education (BGEG) School of Environmental Studies China University of Geosciences Wuhan 430074 China Schools of Earth Environment and Water Resources Yangtze University Wuhan 430100 China

The biosorption potential of many different kinds of biomaterials has been widely studied. However, there is little data on the biosorption mechanism of Cr（VI） by dried biomass. So the bio-removal of Cr（VI） ions from aqueous solutions was investigated using dried biomass from a chromium-resistant bacterium. The bacterium was isolated from dewatered sludge samples that were obtained from a sewage treatment plant. Equilibrium and kinetic experiments were performed at different metal concentra- tions, pH values, and biosorbents dosages. The biomass was characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The functional groups in the Bacillus cereus biomass which may play a role in the biosorption process were identified by Fourier transform infrared spectroscopy. The biosorption process was found to be highly pH dependent and the optimum pH for the adsorption of Cr（VI） was 2.0：k0.3 at 30-4-2 ℃. The experimental data fit well with Langmuir and Freundlich models as well as a pseudo-second order kinetic model. The mechanism for the biosorption was also studied by fitting the kinetic data with an intra-particle diffusion model and a Boyd plot. External mass transfer was found to be the rate-determining step for the adsorption process. Biosorption could be an alternative mechanism besides bio-oxidation and bio-reduction for the bioremediation of heavy metals.

关键词： Bacillus cereus Pf-1 biosorption capacity,biosorbents Cr（VI） biomass

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Biosorption of Cr（VI） by carbonized Eupatorium adenophorum and Buckwheat straw： thermodynamics and mechanism

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Frontiers of Environmental Science & Engineering 2014年第6期8卷 960-966页

作者： Jinfa CHEN Ping YANG Dagang SONG Sha YANG Li ZHOU Lei HAN Bo LAI Department of Agricultural Science Xichang College Xichang 615013 China College of Architecture & Environment Sichuan University Chengdu 610065 China

High quality and low cost carbon can be prepared from Eupatorium adenophorum （E. adenophorum） and Buckwheat straw. The biosorbent was used for Cr（VI） removal. The effect of experimental parameters, such as pH, sorbent dosage and temperature were examined and the optimal experimental condition was determned. Solution pH is found influencing the adsorp- tion. Cr（VI） removal efficiency is found to be maximum （98%） at pH= 1. Langmuir and Freundlich adsorption isotherms were applicable to the adsorption process and their constants were evaluated. The adsorption data obtained agreed well with the Langmuir sorption isotherm model. The maximum adsorption capacities for Cr（VI） ranged from 46.23 to 55.19mg.g^-1 for temperature between 298 K and 308 K under the condition of pH = 1.0. Thermodynamic parameters such as free energy change （AG）, enthalpy （AH） and entropy （AS） indicate a spontaneous, endothermic and increased randomness nature of Cr（VI） adsorption. Studies found that the raw E. adenophorum and buckwheat straw mixed materials with simple treatment had a high efficiency for the removal of Cr（VI） and would be a promising adsorbent.

关键词： Eupatorium adenophorum buckwheat straw adsorption Cr（VI） thermodynamics

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Preparation and characterization of β-FeOOH-coated sand and its adsorption of Cr（VI） from aqueous solutions

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Frontiers of Environmental Science & Engineering 2012年第4期6卷 455-462页

作者： Chunhua XU Dandan CHENG Baoyu GAO Zhilei YIN Qinyan YUE Xian ZHAO Shandong Key Laboratory of Water Pollution Control and Resource Reuse School of Environmental Science and EngineeringShandong UniversityJinan 250100China State Key Laboratory of crystal Materials Shandong UniversityJinan 250100China School of Chemistry and Chemical Engineering Shandong UniversityJinan 250100China

Batch adsorption experiments were conducted to explore the adsorption of Cr（VI） in aqueous solutions by fl-FeOOH-coated sand. We investigated the key factors which affected the adsorption process such as adsorbent dosage, initial pH, initial Cr（VI） ion concentration, contact time and temperature. The uptake of Cr（VI） was very rapid and 44.3%, 51.6%, 58.9% of the adsorption happened during the first 180minutes at 293K, 303K and 313K, respectively. The pseudo-second-order rate equation successfully described the adsorption kinetics. To study the adsorption isotherm, two equilibrium models, the Langmuir and Freundlich isotherms, were adopted. At 293K, 303K and 313K, the adsorption capacities obtained from the Langmuir isotherm were 0.060, 0.070 and 0.076 mg Cr（VI） per gram of the adsorbent, respectively. Thermodynamic parameters such as the change of energy, enthalpy and entropy were calculated using the equilibrium constants. The negative value of AGO and the positive value of △H^0 showed that the adsorption of Cr（VI） in aqueous solutions by β-FeOOH-coated sand was spontaneous, endothermic and occurred by physisorption.

关键词： β-FeOOH-coated sand Cr（VI） adsorption isotherm kinetics

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Cellulose Functionalization via ATRP Grafting of Glycidyl Methacrylate for Cr（VI） Adsorption

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Chinese Journal of Chemistry 2013年第12期31卷 1551-1556页

作者： Chunxiang Lin Sha Qiao Danhui Liu Minghua Liu College of Environment & Resources Fuzhou University Fuzhou Fuj ian 350108 China

Cellulose was first grafted with glycidyl methacrylate （GMA） in an ionic liquid via atom transfer radical polymerization （ATRP） and then the introduced epoxy groups were reacted with ethanediamine （EDA） to obtain an amino adsorbent. The grafting copolymer and the obtained adsorbent were characterized by FTIR, aH NMR, TEM and SEM. The results showed that the grafted copolymers had grafted polymer chains with well-controlled molecu- lar weight and polydispersity, the polymerization was a controlled system. The cellulose adsorbent had numerous micropores on the surface and showed high performance for Cr（VI） adsorption. The adsorption behavior was pH dependent and the sorption equilibrium was achieved within 2 h on the adsorbent.

关键词： cellulose functionalization atom transfer radical polymerization （ATRP） ionic liquid sorption Cr（VI）

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不同阳离子修饰磁性膨润土对苯酚和Cr（VI）吸附的比较

不同阳离子修饰磁性膨润土对苯酚和Cr（VI）吸附的比较

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作者：张凌恺西北农林科技大学

学位级别：硕士

随着经济的高速发展,水体中重金属和有机污染问题日益严重。研究如何去除水体中的重金属及有机污染物对保护人体健康及生态环境有着重要的意义。本文选用3种不同碳链长度的单碳链型阳离子修饰剂八烷基三甲基氯化铵（OT-8）、十二烷基三... 详细信息

随着经济的高速发展,水体中重金属和有机污染问题日益严重。研究如何去除水体中的重金属及有机污染物对保护人体健康及生态环境有着重要的意义。本文选用3种不同碳链长度的单碳链型阳离子修饰剂八烷基三甲基氯化铵（OT-8）、十二烷基三甲基溴化铵（DT）、十八烷基三甲基氯化铵（OT-18）和1种双碳链型阳离子修饰剂乙撑基双十四烷基二甲基氯化铵（ET）对磁性膨润土进行修饰,制得了四种不同的阳离子修饰磁性膨润土,通过TOC和FTIR分析各阳离子修饰磁性膨润土的表面结构特征,研究并比较了不同阳离子修饰磁性膨润土对有机污染物苯酚和阴离子型重金属污染物Cr（VI）的吸附动力学、吸附热力学以及等温吸附特征,探究了温度、pH、离子强度和投加量对苯酚和Cr（VI）吸附的影响,并进行了苯酚和Cr（VI）的吸附再生实验,进而探讨和比较不同阳离子修饰磁性膨润土对苯酚和Cr（VI）吸附机制的差异,为阳离子修饰磁性膨润土吸附废水中的阴离子型重金属和有机污染物的研究和应用提供依据。论文取得了如下的结果:（1）各阳离子修饰剂对磁性膨润土进行修饰后,磁性膨润土的TOC均有了显著的提高,各阳离子修饰磁性膨润土TOC含量呈现出ET＞OT-18＞DT＞OT-8的规律。FTIR的结果表明,各阳离子型表面修饰剂均成功修饰到磁性膨润土表面。各阳离子表面修饰剂在磁性膨润土上的修饰率呈现出OT-18＞ET＞DT＞OT-8的规律。碳链长度是影响阳离子修饰剂在磁性膨润土表面修饰率的关键性因素,阳离子表面修饰剂的碳链越长,在磁性膨润土表面的修饰率越高。（2）伪二阶动力学模型是描述苯酚和Cr（VI）在各阳离子修饰磁性膨润土上吸附的最佳动力学模型。各供试磁性膨润土对苯酚和Cr（VI）的吸附于10 min左右均达到平衡。（3）Sips模型是描述苯酚在各阳离子修饰磁性膨润土上吸附的最佳等温吸附模型。阳离子修饰剂的修饰增强了磁性膨润土对苯酚的吸附能力。各阳离子修饰磁性膨润土对苯酚的饱和吸附量呈现出ET＞OT-18≈DT＞＞OT-8的规律,双碳链型阳离子修饰磁性膨润土对苯酚的饱和吸附量要显著高于单碳链型阳离子修饰磁性膨润土。单碳链型阳离子修饰剂碳链越长,其修饰后的磁性膨润土对苯酚的饱和吸附量就越大。各阳离子修饰磁性膨润土的饱和吸附量均呈现出随修饰比例的增加而增加的趋势。（4）Sips模型是描述Cr（VI）在各阳离子修饰磁性膨润土上吸附的最佳等温吸附模型。阳离子修饰剂的修饰增强了磁性膨润土对Cr（VI）的吸附能力。三种单碳链型阳离子修饰磁性膨润土对Cr（VI）的饱和吸附量呈现出OT-18＞DT＞OT-8的规律,阳离子修饰剂的碳链越长,其修饰后的磁性膨润土对Cr（VI）的饱和吸附量就越高。双碳链型阳离子修饰磁性膨润土对Cr（VI）的饱和吸附量在修饰比例为50%和100%时高于三种单碳链型阳离子修饰磁性膨润土,而在修饰比例为150%时低于OT-18阳离子修饰磁性膨润土。各阳离子修饰磁性膨润土对Cr（VI）的饱和吸附量均随修饰比例的增加而增加。（5）各供试磁性膨润土对苯酚和Cr（VI）的吸附均以物理吸附为主,吸附能力均随温度的升高而降低,吸附均为放热自发的过程。pH值的增加不利于苯酚和Cr（VI）在各供试磁性膨润土上的吸附,而离子强度的增加有利于苯酚的吸附,不利于Cr（VI）的吸附。（6）各供试磁性膨润土对苯酚和Cr（VI）的去除率均随着投加量的增加而增加,而吸附量随着投加量的增加而降低。100ET修饰磁性膨润土、100OT-18修饰磁性膨润土有着良好的再生性能,再生三次后,100ET修饰磁性膨润土对苯酚仍能保持89.9%的吸附能力,100OT-18对Cr（VI）仍能保持79.7%的吸附能力。阳离子表面修饰剂的修饰增强了磁性膨润土对苯酚和Cr（VI）的吸附能力,碳链长度和修饰比例是影响阳离子修饰磁性膨润土对苯酚和Cr（VI）吸附能力的关键性因素。

关键词：磁性膨润土阳离子表面修饰剂苯酚 Cr（VI）吸附

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