Adsorption of phenol on a novel adsorption material PEI/SiO2

In this paper, functional macromolecule polyethyleneimine (PEI) was grafted onto the surfaces of silica gel particles via the coupling effect of gamma-chloropropyl trimethoxysilane (CP), and the novel adsorption material PEI/SiO2 with strong adsorption ability for phenol was prepared. The adsorption properties of PEI/SiO2 for phenol were researched by both static and dynamic methods. The experimental results show that PEI/SiO2 possesses very strong adsorption ability for phenol, and the saturated adsorption amount could reach to 160 mg g(-1). The empirical Freundlich isotherm was found to describe well the equilibrium adsorption data. pH and grafting amount of PEI have great influence on the adsorption amount. Diluted sodium hydroxide solution is used as eluent, and the adsorbed phenol is eluted easily from PEI/SiO2.     

A facile synthesis of Cu(2)O/SiO(2) and Cu/SiO(2) core-shell octahedral nanocomposites

We report here a simple approach to the synthesis of Cu(2)O/SiO(2) core-shell nanocomposites in water solution. The Cu(2)O cores have a perfect octahedral structure with uniform size of about 200-300?nm. A compact SiO(2) shell 9?nm in thickness is located at the surfaces of Cu(2)O octahedra, and it is composed of fine SiO(2) nanoparticles. During the depositing of the SiO(2) particles, as we presumed, dynamic absorbing and disengaging of Na(+) at the interface of Cu(2)O octahedra and the solution made it possible for the formation of Cu-O-Si bonds between core and shell in the composites. The existence of Cu-O-Si bonds in our core-shell composite can be substantiated by peak changes at?1236 and 1080?cm(-1) in the FT-IR spectra. This is the reason why the SiO(2) shell is so compact and uniform. Moreover, these Cu(2)O/SiO(2) core-shell octahedra were further used as precursors, depending on a simple disproportionation reaction of Cu(2)O in acid, to easily achieve Cu/SiO(2) movable multicore-shell octahedral nanocomposites. In the final Cu/SiO(2) core-shell composite, the thin SiO(2) octahedral shell was held, inside of which formed several free Cu nanoparticles 50-80?nm in size. Studies on the Cu(2)O/SiO(2) core-shell octahedral composites and Cu/SiO(2) movable multicore-shell octahedral nanocomposites would be a good thing not only for fundamental research but also for applications.     

Chlorobenzene, chloroform, and carbon tetrachloride adsorption on undoped and metal-doped sol-gel substrates (SiO(2), Ag/SiO(2), Cu/SiO(2) and Fe/SiO(2))

Adsorption isotherms of chlorobenzene, chloroform and carbon tetrachloride vapors on undoped SiO(2), and metal-doped Ag/SiO(2), Cu/SiO(2) and Fe/SiO(2) substrates were measured in the temperature range of 398-593K. These substrates were prepared from a typical sol-gel technique in the presence of metal dopants that rendered an assortment of microporous-mesoporous solids. The relevant characteristic of these materials was the different porosities and micropore to mesopore volume ratios that were displayed; this was due to the effect that the cationic metal valence exerts on the size of the sol-gel globules that compose the porous solid. The texture of these SiO(2) materials was analyzed by X-ray diffraction (XRD), FTIR, and diverse adsorption methods. The pore-size distributions of the adsorbents confirmed the existence of mesopores and supermicropores, while ultramicropores were absent. The Freundlich adsorption model approximately fitted the chlorinated compounds adsorption data on the silica substrates by reason of a heterogeneous energy distribution of adsorption sites. The intensity of the interaction between these organic vapors and the surface of the SiO(2) samples was analyzed through evaluation of the isosteric heat of adsorption and standard adsorption energy; from these last results it was evident that the presence of metal species within the silica structure greatly affected the values of both the amounts adsorbed as well as of the isosteric heats of adsorption.     

Optical properties of the synthetic nanocomposites SiO2/CdS/poly(styrene-co-maleic anhydride) and SiO2/CdS/poly(styrene-co-maleimide)

Hybrid materials consisting of SiO2/CdS particles dispersed in poly(styrene-co-maleic anhydride) and poly(styrene-co-maleimide) have been synthesized and characterized. The polymer nanocomposites were synthesised in situ in the presence of previously prepared inorganic fillers (SiO2/CdS). The nanocomposites were synthesized with the use of as-prepared or surface-modified SiO2/CdS fillers. For both types of nanocomposites, the optical properties were evaluated and the observation of size quantization effects in the optical spectra is discussed. In this context, the influence of the inorganic fillers and polymer matrices on the optical properties of the final nanocomposites was investigated.     

End-functional silicone coupling agent modified PEO/P(VDF-HFP)/SiO(2) nanocomposite polymer electrolyte DSSC

The end-functional silicone coupling agent (dodecyl-trimethoxysilane, DTMS for short) was used to modify the PEO/P(VDF-HFP)/SiO(2) nanocomposite polymer electrolyte (CPE) and the different amounts of DTMS modification effects were studied. The experiments showed the silicone coupling agent with hydrophobic alkyl chains (-C(12)H(25)) chemically engineered on the SiO(2) nanoparticles, and formed a Si-O-Si cross-linked network in the new nanocomposite polymer electrolyte. Proper content of DTMS modified CPE exhibited improved ionic conductivity and the connection with the photoanode and counter electrode. However, much higher content of the DTMS modification changed the conformation of the polymer network and reduced the ionic movement. Compared with the performance (3.84%) of the original DSSC, the DSSC with functional silicone coupling agent modified CPE (DTMS:SiO(2) = 2:1, mol ratio) exhibited improved J(sc) (7.94?mA?cm(-2)), V(oc) (0.624?V) and optimal efficiency (5.2%) (measured at AM1.5, light intensity of 58.4?mW?cm(-2)). The V(oc) of the silicone coupling agent modified polymer electrolyte DSSC is obviously improved, which is mainly due to that the hydrophobic alkyl chain end groups formed an insulating layer that retarded the electron recombination at the TiO(2) nanoporous photoanode/polymer electrolyte interface. The DTMS:SiO(2) = 2:1 modified CPE type DSSC exhibited a performance of 6.42% at a light intensity of 32.1?mW?cm(-2) and 4.94% at 99.2?mW?cm(-2).     

Supported Cu(II) polymer catalysts for aqueous phenol oxidation

Supported Cu(II) polymer catalysts were used for the catalytic oxidation of phenol at 30 degrees C and atmospheric pressure using air and H(2)O(2) as oxidants. Heterogenisation of homogeneous Cu(II) catalysts was achieved by adsorption of Cu(II) salts onto polymeric matrices (poly(4-vinylpyridine), Chitosan). The catalytic active sites were represented by Cu(II) ions and showed to conserve their oxidative activity in heterogeneous catalysis as well as in homogeneous systems. The catalytic deactivation was evaluated by quantifying released Cu(II) ions in solution during oxidation, from where Cu-PVP(25) showed the best leaching levels no more than 5 mg L(-1). Results also indicated that Cu-PVP(25) had a catalytic activity (56% of phenol conversion when initial Cu(II) catalytic content was 200 mg L(Reaction)(-1)) comparable to that of commercial catalysts (59% of phenol conversion). Finally, the balance between activity and copper leaching was better represented by Cu-PVP(25) due to the heterogeneous catalytic activity had 86% performance in the heterogeneous phase, and the rest on the homogeneous phase, while Cu-PVP(2) had 59% and CuO/gamma-Al(2)O(3) 68%.     

Electrochemical degradation of phenol using electrodes of Ti/RuO(2)-Pt and Ti/IrO(2)-Pt

Electrochemical degradation of phenol was evaluated at two typical anodes, Ti/RuO(2)-Pt and Ti/IrO(2)-Pt, for being a treatment method in toxic aromatic compounds. The influences of current density, dosage of NaCl, initial phenol concentration on electrochemical phenol degradation were investigated. It was found that Ti/RuO(2)-Pt anode had a higher oxygen evolution potential than Ti/IrO(2)-Pt anode, which will increase the current efficiency for electrochemical degradation, and the instantaneous current efficiency (ICE) was relatively higher at the initial time during phenol electrolysis. HOCl formed during electrolysis would play an important role on the oxidation of phenol. For the Ti/RuO(2)-Pt anode, phenol concentration decreased from around 8mg/L to zero after 30min of electrolysis with 0.3g/L NaCl as supporting electrolyte at the current density of 10mA/cm(2). Although phenol could be completely electrochemical degraded at both Ti/RuO(2)-Pt and Ti/IrO(2)-Pt anodes, phenol degradation was slower at the Ti/IrO(2)-Pt anode than at the Ti/RuO(2)-Pt anode due to the fact that passivation was to be found at the Ti/IrO(2)-Pt anode.     

Adsorption and aggregation of Fe(III)-hydroxy complexes during the photodegradation of phenol using the iron-added-TiO(2) combined system

The behavior of Fe(III) aquacomplexes in TiO(2) suspensions in the degradation of phenol has been investigated. The most active Fe(OH)(2+) species adsorbed on the surface of TiO(2) retards the conversion of Fe(OH)(2+) into oligomers and therefore increases the percentage of Fe(OH)(2+) with irradiation time, with a consequent enhancement in the catalytic cycle of Fe(III)/Fe(II) and excited charge traps by Fe(III) in the iron-TiO(2) system. The influence of iron addition on TiO(2) was obtained when the regeneration of [Fe(OH)(2+)] remained continuous with irradiation time. In an optimum TiO(2) suspension (0.5g/L) with the addition of 0.1mM Fe(III), the measured k(obs) values for phenol degradation were enhanced for the higher adsorption of Fe(OH)(2+) on the reactive surface of TiO(2) at a specified irradiation time.     

表面印迹聚烯丙基胺硅胶材料的制备研究

以硅胶为基体,聚烯丙基胺(PAA)为表面修饰剂,ECH为交联剂,制备了铜表面印迹材料IIP-PAA/SiO2。考察了印迹条件对印迹材料吸附性能的影响,结果为:n(Cu2+):n(N)为0.5,n(ECH):n(N)为0.6,印迹温度323K,时间3h,甲醇为反应介质。合成的IIP-PAA/SiO2材料对Cu(Ⅱ)的吸附性能明显优于PAA/SiO2和NIP材料。在相同条件下,印迹材料的铜吸附量达到0.631mmol·g-1,铜锌选择性系数为56.3,相对选择性系数为26.0。另外印迹材料具有再生吸附性能,经过5次吸附-解吸循环后,其吸附容量维持在90.2%以上。     

SiO2/聚（3-羟基丁酸酯-co-4-羟基丁酸酯）薄膜研究

目的研究纳米SiO2对可生物降解聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(P34HB)包装膜结晶行为和力学性能的影响。方法采用溶液浇铸法制备SiO_2/P34HB纳米复合薄膜,利用红外光谱仪(FTIR)、扫描电镜(SEM)、正置热台显微镜(POM)、差示扫描量热仪(DSC)和万能力学试验机等研究纳米SiO_2对P34HB结构、结晶性和力学性能等的影响。结果纳米SiO_2在P34HB中起到异相成核的作用,SiO2/P34HB复合膜的结晶速率和结晶度得到明显改善。相比P34HB包装膜,当纳米SiO_2质量分数为2%时,SiO_2/P34HB复合膜的弹性模量和拉伸强度分别提高了72.7%和60.9%。结论获得了纳米SiO2改善可生物降解聚(3-羟基丁酸酯-co-4-羟基丁酸酯)包装膜结晶度和力学性能的最佳掺杂比例参数。     

SiO2/SnO2复合凝胶对丙酮和氨气的吸附动力学研究

应用溶胶－凝胶法制备了SiO2/SnO2复合凝胶，测定了红外光谱，采用静态吸附法测定了不同组成的SiO2/SnO2复合凝胶对丙酮气体和氨气的吸附动力学曲线。结果表明，SiO2与SnO2凝胶的复合有利于气体的吸附，在凝胶中含有一定的羟基是吸附性强的根源。数据拟合得到的吸附动力学方程分别为x=c1(1-exp(-c2t)和x=c′1t/(1 c2′t)的形式，说明SiO2/SnO2复合凝胶对丙酮气体和氨气的吸附机理分别具有单活性位和双活性位吸附特征。     

纳米 SiO 2/ LiClO 4/ PVDF2 HFP复合凝胶聚合物电解质的制备及其电化学性能

为了解决液态电解质锂离子电池存在的安全性问题 , 以偏氟乙烯和六氟丙烯的共聚物( PVDF2 HFP)为基体 , 通过加入高氯酸锂(LiClO 4) 、 增塑剂(碳酸丙烯酯和碳酸二甲酯) 、 纳米二氧化硅等 , 制备出了具有高电导率的复合凝胶聚合物电解质。用 X射线衍射仪测试聚合物电解质的结构 , 用交流阻抗法测定其电导率 , 用线性伏安扫描法研究了该聚合物电解质体系的电化学稳定性 , 并以其为电解质制备成锂离子电池进行充放电测试。结果- 3表明 , 在 20℃ 时复合凝胶聚合物电解质的电导率最高可达 7. 56×10 S/ cm , 该电解质在 41 6 V 以下电化学窗口稳定 , 以其为电解质的锂离子电池具有良好的电化学性能 , 说明纳米 SiO 2/ LiClO 4/ PVDF2 HFP复合凝胶聚合物电解质能满足锂离子电池的应用。     

中空型分子印迹聚合物的制备及其对4-甲基二苯并噻吩的吸附性能研究

以SiO2为载体,4-乙烯基吡啶为功能单体,结合牺牲载体法合成了一种具有特异性识别4-甲基二苯并噻吩的中空型分子印迹聚合物。利用傅立叶变换红外光谱、氮气吸附实验、扫描电镜对形态结构进行了表征。通过在模拟油中的静态吸附试验,对印迹聚合物的吸附性能进行了研究。结果表明,在SiO2表面成功地合成了具有多孔结构的分子印迹层,经过牺牲载体法处理后得到的中空分子印迹聚合物具有更好的表面特性,提高了吸附性能。中空型分子印迹聚合物对4-甲基二苯并噻吩表现出良好的特异性识别性能,吸附动力学满足Langergren准二级动力学方程,等温线符合Freundlich等温线模型,吸附热力学研究表明吸附是自发的吸热过程,在328K下的吸附容量为18.31498mg/g,吸附平衡时间为3h。     

Synthesis of Fe3O4/SiO2/Polypyrrole magnetic nanocomposite polymer powder: Investigation of structural properties and ability to purify of edible sea salts

In this study, Fe₃O₄/SiO₂/polypyrrole magnetic nanocomposite polymer powder was chemically synthesized. The structure of the prepared composite powders were studied using scanning electron microscopy, FTIR and XRD techniques. The results showed that the prepared composites have a nanometer structure. The FTIR results confirmed the electrostatic interactions between the composite components. XRD also showed the crystal structure of Fe₃O₄ and its composites. Optimal nanocomposite powder was used to purify the salt of Lake Urmia. Salt samples were treated with powder and the chemical properties of salt were investigated before and after treatment. Qualitative tests performed on salt included COD, BOD, organic compounds, heavy metals, nitrate and nitrite, and color characteristics. Finally, the efficiency of the nanoparticle powder in the lake salt treatment was calculated. The results showed that the composite powder reduced BOD and COD as well as the heavy metal salts of the lake. Also, the organic compounds in the salt decreased and the color factors such as the white index of the salt increased. Under optimal conditions, Fe₃O₄/SiO₂/PPy composite showed the best performance at 37 min of purification time. In general, Fe₃O₄/SiO₂/PPy composite can be easily used to purify sea salts and also reduce environmental pollutants.     

Effect of SiO2 Concentration on the Electrical Conductivity of M2(WO4)3/SiO2 (M = La,Sm) Composites

Inorganic Materials - Composites with the general formulas (1 – x)La2(WO4)3–xSiO2 and (1 – x)Sm2(WO4)3–xSiO2 have been prepared by solid-state reactions. The phase...     

The effect of an SiO(2) buffer layer on the SAW properties of ZnO/SiO(2)/GaAs structure

The effect of an SiO(2) buffer layer on the surface acoustic wave (SAW) properties of ZnO/SiO(2)/GaAs structure is examined. Both theoretical and experimental results show that the coupling coefficient is increased appreciably by providing an SiO(2 ) film between the ZnO film and the GaAs substrate. Adding an SiO (2) film is also beneficial to the promotion of quality of ZnO thin film. The results could be useful for the further development of monolithic SAW devices.     

Adsorption character for removal Cu(II) by magnetic Cu(II) ion imprinted composite adsorbent

A novel magnetic Cu(II) ion imprinted composite adsorbent (Cu(II)-MICA) was synthesized, characterized and applied for the selective removal Cu(II) from aqueous solution in the batch system. The adsorption-desorption and selectivity characteristics were investigated. The maximum adsorption occurred at pH 5-6. The equilibrium time was 6.0h, and a pseudo-second-order model could best describe adsorption kinetics. The adsorption equilibrium data fit Langmuir isotherm equation well with a maximum adsorption capacity of 46.25mg/g and Langmuir adsorption equilibrium constant of 0.0956L/mg at 298K. Thermodynamic parameters analysis predicted an exothermic nature of adsorption and a spontaneous and favourable process that could be mainly governed by physisorption mechanism. The relative selectivity coefficients of Cu(II)-MICA for Cu(II)/Zn(II) and Cu(II)/Ni(II) were 2.31, 2.66 times greater than the magnetic non-imprinted composite adsorbent (MNICA). Results suggested that Cu(II)-MICA was a material of efficient, low-cost, convenient separation under magnetic field and could be reused five times with about 14% regeneration loss.     

Effective in situ material properties of micron-sized SiO2 particles in SiO2 particulate polymer composites

Several analytical models exist for determination of the Young’s modulus and coefficient of thermal expansion (CTE) of particulate composites. However, it is necessary to provide accurate material properties of the particles as input data to such analytical models in order to precisely predict the composite’s properties, particularly at high particle loading fractions. In fact, the constituent’s size scale often presents a technical challenge to accurately measure the particles’ properties such as Young’s modulus or CTE. Moreover, the in situ material properties of particles may not be the same as the corresponding bulk properties when the particles are embedded in a polymer matrix. To have a better understanding of the material properties and provide useful insight and design guidelines for particulate composites, the concept of “effective in situ constituent properties” and an indirect method were employed in this study. This approach allows for the indirect determination of the particle’s in situ material properties by combining the experimentally determined composite and matrix properties and finite element (FE) models for predicting the corresponding composite properties, then backing out the effective in situ particle properties. The proposed approach was demonstrated with micron-size SiO₂ particle reinforced epoxy composites over a range of particle loading fractions up to 35 vol.% by indirectly determining both the effective Young’s modulus and the effective CTE of the particles. To the best of our knowledge, this study is the first published report on the indirect determination of both the Young’s modulus and the CTE of micron size particles in particulate composites. Similar results on Young’s modulus of micron-size SiO₂ particles measured from nano-indentation testing are encouraging.