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surface chemistry of polymer-supported nano-hydrated ferric oxide for arsenic removal: effect of host pore structure

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Science China chemistry 2015年第4期58卷 722-730页

作者： Guangze Nie Jing Wang Bingcai Pan Lu Lv State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Nanjing University

Immobilization of hydrous ferric oxide(HFO) particles inside solid hosts of porous structure is an important approach to improve their applicability in advanced water treatment such as arsenic and heavy metal removal. Here, we fabricated three polystyrene(PS)-based nano-HFOs and explored the effect of host pore structure on the surface chemistry of the immobilized HFOs. Potentiometric titration of the hybrids and surface complexation modeling of their adsorption towards arsenite and arsenate were performed to evaluate the surface chemistry variation of the loaded HFOs. Polymer hosts of higher surface area and narrower pore size would result in smaller particle size of HFOs and lower the value of the point of zero charge. Also, the site density(normalized by Fe mass) and the deprotonation constants of the loaded HFOs increased with the decreasing host pore size. Arsenite adsorption did not change the surface charge of the loaded HFOs, whereas arsenate adsorption accompanied more of the negative surface charges. Adsorption affinity of both arsenic species with three HFO hybrids were compared in terms of the intrinsic surface complexation constants optimized based on the adsorption edges. HFO loaded in polystyrene host of smaller pore size exhibits stronger affinity with arsenic species.

关键词： hydrated ferric oxide arsenic adsorption nanocomposite surface chemistry

surface chemistry of electrode materials toward improving electrolyte-wettability:A method review

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InfoMat 2024年第11期6卷 31-65页

作者： Lei Zhao Yuanyou Peng Peiyao Dou Yuan Li Tianqi He Fen Ran State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals Department of Polymeric Materials Science and EngineeringSchool of Materials Science and EngineeringLanzhou University of TechnologyLanzhouthe People's Republic of China

The electrolyte-wettability at electrode material/electrolyte interface is a criticalfactor that governs the fundamental mechanisms of electrochemical reactionefficiency and kinetics of electrode materials in practical electrochemicalenergy storage. Therefore, the design and construction of electrode materialsurfaces with improved electrolyte-wettability has been demonstrated to beimportant to optimize electrochemical energy storage performance of electrodematerial. Here, we comprehensively summarize advanced strategies and keyprogresses in surface chemical modification for enhancing electrolytewettabilityof electrode materials, including polar atom doping by post treatment,introducing functional groups, grafting molecular brushes, and surfacecoating by in situ reaction. Specifically, the basic principles, characteristics,and challenges of these surface chemical strategies for improving electrolytewettabilityof electrode materials are discussed in detail. Finally, the potentialresearch directions regarding the surface chemical strategies and advancedcharacterization techniques for electrolyte-wettability in the future are *** review not only insights into the surface chemical strategies forimproving electrolyte-wettability of electrode materials, but also provides strategicguidance for the electrolyte-wettability modification and optimization ofelectrode materials in pursuing high-performance electrochemical energy storagedevices.

关键词： chemical modification electrochemical energy storage electrode materials electrode/electrolyte Interface surface chemistry

surface chemistry of nanoscale Fe_3O_4 dispersed in magnetic fluids

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Science China chemistry 2007年第6期50卷 754-758页

作者： Bernd GüNTHER Fraunhofer Institut für Fertigungstechnik und Angewandte Materialforschung D-28359 Bremen Germany

The interaction between stabilizers and nanoparticles is one of the important factors to prepare stable magnetic fluids. The magnetic nano-size Fe3O4 core with single domain and the average grain size around 8-12 nm were prepared by chemical precipitation method. The O/Fe molar ratio of the particle surface was measured by X-ray photoelectron spectroscopy (XPS). The heat effects of stabilizers ad- sorption on nanoparticles were measured by solution calorimetry. The excess amount of oxygen was possibly the result of the hydroxygen formed on the surface of the nanoparticles. The heat effects showed that compounds containing carboxyl groups can be adsorbed chemically on magnetite by forming chemical bonds. The other stabilizers involving NH-groups, such as polyethylene-imine, can be adsorbed physically. The exothermic value is about half of the former case.

关键词： nanoscale materials heat effect magnetic fluids surface chemistry

Tuning microstructure and surface chemistry of reduced graphene oxide by mild reduction

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Journal of Central South University 2016年第8期23卷 1823-1830页

作者：冷娴刘如铁邹俭鹏熊翔何捍卫 State Key Laboratory of Powder Metallurgy Central South University

Reduced graphene oxide(RGO) sheets with varied contents and types of oxygenated groups were synthesized by Hummers treatment of natural graphite powders followed by different nontoxic and mild reduction methods, which include thermal and chemical reduction with ethylene glycol, KOH and Fe powder. The changes in microstructure and surface chemistry of RGOs were extensively characterized by SEM, TEM, AFM, XRD, XPS and Raman spectrum. The results show that significant exfoliation occurs during oxidation and is retained in reduction processes, along with the formation of curled wavy morphology. Compared with large d spacing(0.852 nm) of graphene oxide(GO), the(002) plane distance decreases to 0.358-0.384 nm of RGOs, indicating efficient tuning of surface functionalities through mild reduction methods. The ID/IG ratio of RGOs is about 1.0-1.15, indicating that reconstructed sp^2 domains have smaller sizes and larger quantity. The content of sp^2 bonded C in GO(36.93%, molar fraction) increases to 45.48%-72.92%(molar fraction) in RGOs, along with a drastic decrease in hydroxyl and epoxy and minor changes in carbonyl and carboxyl. Thermal reduction or chemical reduction produces RGOs with residual functionalities, which may render different chemical activity and is desirable in various applications.

关键词： graphene oxide reduction oxygen functionality surface chemistry

Influence of heating rate on reactivity and surface chemistry of chars derived from pyrolysis of two Chinese low rank coals

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International Journal of Mining Science and Technology 2018年第4期28卷 610-616页

作者： Liang Dingcheng Xie Qiang Li Guangsheng Cao Junya Zhang Jun School of Chemical and Environmental Engineering China University of Mining and Technology (Beijing)

A series of char samples were derived from pyrolysis of two typical low-rank coals in China （Shengli lig- nite and Shenmu bituminous coal） at low, medium and fast heating rates, respectively, to the same pyrol- ysis temperature 750℃. Then these chars were characterized by means of thermogravimetric analysis and Fourier transform infrared spectrometer with the aim to investigate the influence of heating rate in pyrolysis process on gasification reactivity and surface chemistry of them. Besides, a homogeneous model was used to quantitatively analyze the activation energy of gasification reaction. The results reveal that Shengli lignite and its derived chars behave higher gasification reactivity and have less content of oxygen functional groups than Shenmu coal and chars. Meanwhile, chars derived from Shengli lignite at 50℃/min and Shenmu coal at 200℃/min have the greatest gasification reactivity, respectively. The oxygen functional groups in Shengli lignite are easily thermo-decomposed, and they are less affected by the heating rate, while that in Shenmu coal have a significant change with the variation of heating rate. In addition, there is no good correlation between the change of oxygen functional groups and that of the gasification reactivity of the derived chars from pyrolysis at different heating rates.

关键词： Pyrolysis Low rank coal Heating rateReactivity Kinetic parameter surface chemistry

EFFECT OF HYPERCROSSLINKED RESINS surface chemistry ON THE ADSORPTION OF PHENOL FROM AQUEOUS SOLUTION

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Chinese Journal of Polymer Science 2006年第6期24卷 585-591页

作者： Guan-hua Meng Ai-min Li Wei-ben Yang Fu-qiang Liu Quan-xing Zhang State Key Laboratory of Pollution Control and Resources Reuse School of the Environment Nanjing University Nanjing 210093 China Engineering Technology Research Center of Organic Toxie Substance Control and Resource Reuse of Jiangsu Province Nanjing 210038 China

Two hypercrosslinked resins with similar physical characters but different surface chemistry were synthesized and used to remove phenol from aqueous solutions. The FTIR spectra, elemental analysis and the Boehm titration were used to characterize the chemical properties of the resins. The adsorption experiments were carried out using the bottle-point technique, and the effects of the surface chemistry on the adsorption were discussed. The adsorption data fit well with the Freundlich model, indicating the heterogeneity of the resins surface. It could be seen from the experimental results that the adsorption capacity increased with the increase in the total surface concentration of oxygen-containing groups. The pH dependence and the effects of ionic strength were also discussed. The kinetic adsorption data fit well with the pseudo-second order model, and the results showed that the surface oxygen-containing groups have little effect on the adsorption rate.

关键词： Hypercrosslinked resin Phenol surface chemistry Adsorption isotherm Kinetic study.

Functional carbon materials addressing dendrite problems in metal batteries:surface chemistry,multi-dimensional structure engineering,and defects

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Science China chemistry 2022年第12期65卷 2351-2368页

作者： Qi Yang Na Jiang Yuan Shao Yong Zhang Xin Zhao You Zeng Jieshan Qiu State Key Laboratory of Chemical Resource Engineering College of Chemical EngineeringBeijing University of Chemical TechnologyBeijing 100029China

Metal batteries that directly use active metals as anodes are considered as one of the most promising solutions to achieve the energy upgrade of battery technologies,while their practical application still suffers from dendrite *** carbon materials(FCMs)have demonstrated their great potential in suppressing metal dendrites benefitting from the multiple merits such as chemical tunability and capability of multi-dimensional structure ***,we initiate a review to present the recent progress in employing FCMs to deal with dendrite *** focuses on the surface chemistry and multi-dimensional carbon material engineering,which systematically overcomes the problems through diverse methods,such as reinforcing desolvation,improving interface compatibility,homogenizing electric field,buffering volume expansion and lattice *** addition,we also refine the long-standing debate about whether surface defects in FCMs are beneficial to suppress the metal dendrites or not,especially in the non-aqueous electrolyte ***,the remaining challenges for utilizing FCMs to suppress metal dendrites and the possible solutions are proposed to guide the future development.

关键词： Functional carbon materials metal dendrites surface chemistry multi-dimensional carbon material engineering defect

Textural characteristics,surface chemistry and oxidation of activated carbon

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Journal of Natural Gas chemistry 2010年第3期19卷 267-279页

作者： Wan Mohd Ashri Wan Daud Amir Hossein Houshamnd Department of Chemical Engineering Faculty of EngineeringUniversity of Malaya

Numerous researches were reviewed and interpreted to depict a comprehensive illustration of activated carbon and its behavior towards *** carbon as one of the most important adsorbents is tried to be described in this review paper by terms of its＂Textural Characteristics＂and＂surface chemistry＂.These two terms,coupled with each other,are responsible for behavior of activated carbon in adsorption processes and in catalytic *** as-prepared activated carbons are usually nonselective and their surfaces suffer from lack of enough reactive groups,their different aspects may be improved and developed by diverse types of *** is one of the most conventional modifications used for activated *** may be used as a final modification or as a pre-modification followed by further *** this paper,methods of oxidation of activated carbon and other graphene-layer carbon materials are introduced and wet oxidation as an extensively-used category of oxidation is discussed in more detail.

关键词： activated carbon graphene-layer carbon surface chemistry textural characteristics oxidation

Quantum confinement and surface chemistry of 0.8–1.6 nm hydrosilylated silicon nanocrystals

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Chinese Physics B 2014年第7期23卷 565-572页

作者：皮孝东王蓉杨德仁 State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering Zhejiang University

In the framework of density functional theory （DFT）, we have studied the electronic properties of alkene/alkyne- hydrosilylated silicon nanocrystals （Si NCs） in the size range from 0.8 nm to 1.6 nm. Among the alkenes with all kinds of functional groups considered in this work, only those containing -NH2 and -C4H3S lead to significant hydrosilylation- induced changes in the gap between the highest occupied molecular orbital （HOMO） and the lowest unoccupied molecular orbital （LUMO） of an Si NC at the ground state. The quantum confinement effect is dominant for all of the alkene- hydrosilylated Si NCs at the ground state. At the excited state, the prevailing effect of surface chemistry only occurs at the smallest （0.8 nm） Si NCs hydrosilylated with alkenes containing -NH2 and -C4H3S. Although the alkyne hydrosilylation gives rise to a more significant surface chemistry effect than alkene hydrosilylation, the quantum confinement effect remains dominant for alkyne-hydrosilylated Si NCs at the ground state. However, at the excited state, the effect of surface chemistry induced by the hydrosilylation with conjugated alkynes is strong enough to prevail over that of quantum confinement.

关键词： silicon nanocrystals hydrosilylation quantum confinement surface chemistry