TiO_2在水及丙二醇介质中表面电性质的研究

Surface charge properties of titanium dioxide in water and propylene g lycol have been discussed by proton-transfer phenomena.Electrophoresis shows s ignificant differences between each type of titanium dioxide particles and betwe en the two dispersion media.In aqueous solvent,the sign of the charge for tita nium dioxide would change due to pH and surface chemical composition.However,i n propylene glycol pH value could not result in the sign of the charge for uncoa ted titanium dioxide.Furthermore,the effects of both alumina and silica coatin gs and media on the surface charge properties of titanium dioxide are due to pro ton-transfers.The acidity of hydroxyl groups on oxides surface is believed to be the direct reason that make them have different charge properties in solvents .It is favorable for the hydroxyl groups on the surface of particles to donate protons,as was observed by negative charge pertaining for dispersion in water a t most values of pH.While in propylene glycol titanium dioxide particles are fo rced to accept protons,resulting in positively charged particles.Small amounts of water have a significant effect on the sign of the charge for uncoated titan ium dioxide.

施用不同氮肥对砖红壤表面电化学性质的影响

就土壤有效养分的保蓄和提供而言，土壤对氮素的吸附量及强度大小对其有重要影响．以砖红壤为研究对象，采用土柱淋溶方法，研究了施用不同氮肥对砖红壤表面电化学性质的影响，探讨了土壤保蓄和提供植物有效养料．结果表明：（1） CK处理的土壤表面电荷数比原土明显下降了6.24％；在低氮肥水平（100，200 mg／kg）下，硝铵处理的表面电荷量显著高于原土；而硫铵和尿素处理比原土低6.51％和1.42％；在高氮肥水平（300，400 m g／kg ）下，3种氮肥处理的表面电荷数与原土无明显差异．（2）与原土相比，3种氮肥处理的比表面积均显著增大，其中尿素处理的比表面积随施氮水平的变化而显著增大，特别是N3和N4处理的比表面积显著高于 N1和 N2处理．（3）随着施氮量的增加，砖红壤的表面电荷密度和电场强度呈相同的增加趋势．在同一施氮水平下，尿素处理的砖红壤表面电荷密度和电场强度均显著高于硝铵和硫铵处理，其中N4比X4处理高了98.6％．土壤表面电化学性质会影响氮肥所转化的NO3－的淋失、氢离子的吸附以及交换性盐基离子淋失，为科学施氮，调节土壤—作物体系的氮素平衡，故在选择施用氮肥时应适当适量．本试验条件下，尿素相较于其他两种氮肥更适合砖红壤，且氮肥的合理施用量应控制在350～400 kg／hm2．

不同种类氮肥对紫色土表面电化学性质的影响

以紫色土为研究对象,采用土柱淋溶方法,研究了不同种类氮肥对紫色土表面电化学性质的影响。结果表明:氮肥处理的紫色土表面电荷量较原土大,增加量在0.05～0.7 cmol kg-1;在低氮水平(100、200 mg kg-1)下,紫色土表面电荷量为尿素>硫铵>硝铵;而在高氮水平(300、400 mg kg-1)下,表面电荷量为硫铵>尿素>硝铵。与原土相比,施肥处理的紫色土比表面积有所增加,其中施用100 mg kg-1尿素的增加量最大,较原土增加了78.04%,且尿素处理对土壤比表面积的影响显著高于其余两种氮肥处理;而400 mg kg-1硫铵处理的增加量最少,只增加了0.06%。在同一个施氮水平下,硫铵处理的土壤表面电荷密度和电场强度最大,而尿素处理的最小;低氮施肥处理对电荷密度和电场强度的影响明显高于高氮施肥处理。可见,不同氮肥种类和施氮水平由于电解质体系类型和浓度的差异,引起土壤pH变化,最终对土壤电化学性质产生影响,从而改变土壤养分的保蓄性和有效性。在本试验条件下,非电解质体系在低浓度下能显著影响紫色土表面电化学性质,而强电解质在高浓度下影响效果较为明显。

不同磷水平塿土的表面性质及其对磷素流失特征的影响

为明确不同磷水平塿土的表面电化学性质特征,阐明电解质浓度调控下塿土表面性质的变化及其与土壤磷素流失特征的内在关联,利用物质表面性质联合测定分析技术,结合降雨模拟试验,研究了长期定位配施磷肥条件下不同磷水平塿土的表面电化学性质及其对土壤磷素流失特征的影响。结果表明:(1)长期施磷处理下的塿土全磷含量为不施磷处理的2.46倍,但其表面电位、表面电荷密度、表面电场强度、比表面积以及表面电荷数量均低于不施磷处理塿土;(2)不同磷水平塿土均表现出土壤颗粒及磷素流失量随着土粒表面电位(绝对值)升高而加剧的趋势,颗粒态磷的累积流失量与土壤颗粒累积流失量间呈线性正相关;(3)由于低磷水平塿土表面电位(绝对值)相对较高,所受土壤颗粒间静电排斥力更大,导致土壤团聚体稳定性较差,土壤颗粒及其附着磷素累积流失量更多;(4)本实验条件下土壤中磷素流失以颗粒态磷为主,占流失总量的81%~99%,溶解态磷占比十分有限。本研究阐明了长期定位施磷处理对土壤表面电化学性质的影响,明确了表面性质变化与土壤颗粒及磷素流失特征的关系,为长期施磷土壤的环境风险防控提供了新思路。

小麦秸秆及其生物炭添加对黄绵土表面电化学性质的影响

土壤表面电化学性质是土壤具有肥力的重要基础,研究小麦秸秆及其生物炭添加对黄绵土表面电化学性质的影响,可为黄绵土耕地质量的提升及可持续利用、减少土壤侵蚀提供重要的理论及实践依据。通过室内恒温培养试验,设置对照(CK)、1%秸秆(J1)、3%秸秆(J3)、5%秸秆(J5)、7%秸秆(J7)、10%秸秆(J10)和1%生物炭(S1)、3%生物炭(S3)、5%生物炭(S5)、7%生物炭(S7)、10%生物炭(S10)11个处理。培养10个月后采集土壤样品,采用物质表面性质联合测定法测定表面电化学参数,包括表面电荷数量(SCN)、比表面积(SSA)、表面电荷密度(σ_(0))、表面电位(φ_(0))、表面电场强度(E_(0)),并通过冗余分析的方法解析了表面电化学性质与土壤基本理化性质之间的关系。结果表明:(1)施用秸秆和生物炭后,土壤碳酸盐含量下降,有机碳(SOC)、电导率、全氮(TN)及碳氮比(C/N)增加。添加秸秆会降低黄绵土的pH,而生物炭则会增加土壤的pH。(2)随着秸秆施用量的增加,Zeta电位下降,施用生物炭后,各个处理的Zeta电位都小于CK,但总体上随生物炭施用量的增加Zeta电位增加。(3)随着秸秆和生物炭施用量的增加,土壤的比表面积(SSA)和表面电荷数量(SCN)均增大。与CK相比,J10和S10的SSA分别提高114.0%和98.1%,SCN提高80.8%和88.3%。施用秸秆能够降低土壤表面电荷密度(σ_(0)),与CK相比,施用秸秆的土壤σ_(0)降低幅度可达5.5%~15.5%。总体上,随生物炭施用量的增加σ_(0)减小,当添加量超过5%后,施用生物炭土壤的σ_(0)小于CK。(4)冗余分析结果显示,有机碳是影响土壤表面电化学性质的最主要因素,其解释量在秸秆和生物炭添加处理中分别占88.1%和89.5%。施用秸秆和生物炭会显著提高黄绵土的有机碳含量,改善土壤基本理化性质。土壤的比表面积和表面电荷数量随秸秆和生物炭添加量的增加而增加,但表面电荷密度总体上呈下降趋势。有机碳含量是影响黄绵土表面电化学性质变化的主控因素。

黄土高原典型植被群落对土壤表面电化学性质的影响及其空间差异

为探究黄土高原不同区域典型植被生长对土壤表面电化学性质的影响,以黄土高原自南向北的3个典型区域(永寿墚、坊塌、六道沟)及2种典型乡土草本植物(铁杆蒿(Artemisia gmelinii Web.)、长芒草(Stipa bungeana Trin.))为研究对象,以退耕1年的撂荒地作为对照,通过土壤样品采集和土壤表面电化学性质的测定,研究典型植被群落对土壤表面电化学性质的影响及其空间差异。结果表明:(1)在黄土高原地区,相较于撂荒地,典型植被群落生长使土壤黏粒、粉粒、有机质含量增加,土壤pH、容重、砂粒含量减少;(2)同一区域内,相较于撂荒地,植被恢复促进了土壤阳离子交换量、比表面积的增加,减少了表面电荷密度和表面电场强度,其变化范围分别为6.69~24.34 cmol/kg,7.29~182.29 m^(2)/g,0.08~2.04 C/m^(2),1.23~28.46 10^(8) V/m;不同区域间,同一植被群落下永寿墚土壤阳离子交换量、比表面积的增量最高,而六道沟土壤表面电化学性质的变化率最高,说明典型植被群落对土壤表面电化学性质的影响具有空间差异性;(3)典型植物群落下土壤粉粒含量和有机质含量与土壤表面电化学性质具有显著的相关性,其变化是影响黄土高原地区土壤电化学性质变化的主要原因,解释率分别为61.0%,11.1%。研究结果为认识黄土高原地区植被恢复及其调控作用提供参考。

电化学抑制煤系黏土岩泥化的表面作用机制

针对煤系黏土岩在洗选过程的泥化问题,考察了不同电位梯度条件下煤系黏土岩的表面电性质和表面润湿性的变化规律,分析了电化学方法抑制煤系黏土岩泥化的表面作用机制。结果表明,电化学作用可以降低颗粒表面离子水化及渗透水化,减弱固液界面之间的相互作用,进而有效抑制煤系黏土岩泥化,该方法从源头上解决煤炭洗选过程中细泥附着、煤泥水难沉降问题。

河口细颗粒泥沙有机絮凝的研究综述及机理评述

河口海岸水域细颗粒泥沙的絮凝研究一直是人们广泛关注的课题,由于河口区水体成分较为复杂,加上水动力条件的影响,因此对絮凝的研究也是众说纷纭,本文针对河口区丰富的有机质,着重分析和综述了有机质对细颗粒泥沙粒径、表面电性质和稳定性的影响以及有机絮凝的热力学理论解释等研究成果,同时对泥沙颗粒有机絮凝的机理和有机―无机复合絮凝的模式进行了详细评述。在此基础上,结合国内有机絮凝研究现状,提出了今后的研究方向。

复合纳米有机硅材料处理花岗岩的性能测定及相互影响

通过电渗的方法探讨一种复合纳米有机硅材料对固体表面电性质的改变作用 ,研究固体表面电性质与摩擦力的相依性。结果表明 ,经该材料处理的固体表面 (花岗岩 ) ,其表面电负性随处理液浓度的增大而减小 ,摩擦力则随着表面电性质的改变而改变。

Effects of Sintering Atmosphere on the Microstructure and Surface Properties of Symmetric TiO2 Membranes

The effects of sintering atmosphere on the properties of symmetric TiO2 membranes are studied with regard to sintering behavior, porosity, mean pore size, surface comPosition. and surface charge properties. The exerimental results show that the symmetric TiO2 membranes display better sintering activity in the air than in argon, and the mean pore diameters and porosities of the membrane sintered in argon are higher than those of the membrane sintered in the air at the same temperature. The surface compositions of the symmetric TiO2 membrane sintered in the air and in argon at different temperatures, as studied by X-ray photoelectron spectroscopy, are discussed in terms of their chemical composition, with particular emphasis on the valence state of the titanium ions. The correlation between the valence state of the titanium ions at the surface and the surface charge properties is examined.It is found that the presence of Ti^3＋, introduced at the surface of the symmetric TiO2 membranes by sintering in a lower partial pressure of oxygen, is related to a significant decrease in the isoelectric point. TiO2 with Ti^4＋ at the interface has an isoelectric point of 5.1, but the non-stoichiometric TiO2-x with Ti^3＋ at the interface has a lower isoelectric point of 3.6.

Enhancement of leaching of cobalt and lithium from spent lithium-ion batteries by mechanochemical process

A mechanochemical method with SiO_(2)as the grinding aid was used to enhance the leaching efficiencies of Co and Li from spent lithium batteries(LIBs).Experiment results show that the optimal leaching efficiencies of 94.91%for Co and 97.22%for Li were obtained under the parameters of SiO_(2)/LiCoO_(2)mass ratio of 1:1,grinding speed of 500 r/min and grinding time of 30 min in citric acid.Characterization results indicate that the surficial properties of LiCoO_(2)were changed after mechanochemical grinding treatment due to the newly generated surfaces on LiCoO_(2).Meanwhile,the incompletely coordinated atomic structure and defective lattice structure lead to the activation of LiCoO_(2).The reduction effect of carbon black on Co^(3+)under the action of mechanical forces increases its leaching efficiencies in the citric acid solution.The proposed process was found efficiently to recover Co and Li from LiCoO_(2).

Influence of nitrogen hetero-substitution on the electrochemical performance of coal-based activated carbons measured in non-aqueous electrolyte

Nitrogen-containing carbons were prepared by modification of activated carbons.The modified carbons were used as electrode materials with improved electrochemical performance.Precursor anthracite was activated by KOH(KOH:anthracite= 1:1), modified by melamine or urea and then treated at 1173 K to obtain the modified carbons.The porous structure, the chemical composition and the electrochemical characteristics of the carbons were investigated by nitrogen sorption, XPS and electrochemical methods respectively.Electrochemical experiments were performed in an organic electrolytic solution of 1 M(C2H5)4NBF4/PC.The samples modified by the different methods showed differences in chemical composition that introduced varying degrees of electrochemical performance enhancement.The presence of nitrogen enhanced the electron donor properties and the surface wettability of the activated carbons:this ensured a sufficient utilization of the exposed surface for charge storage.

Influence of polarized bias and porous silicon morphology on the electrical behavior of Au-porous silicon contacts

This paper reports the surface morphology and I-V curves of porous silicon （PS） samples and related devices. The observed fabrics on the PS surface were found to affect the electrical property of PS devices. When the devices were operated under different external bias （10 V or 3 V） for 10 min, their observed obvious differences in electrical properties may be due to the different control mechanisms in the A1/PS interface and PS matrix morphology.

Galvanic effect of magnetite on electrochemical oxidation of arsenopyrite in acidic culture medium

The galvanic interaction of arsenopyrite−magnetite in acidic culture medium was investigated by electrochemical measurements,X-ray photoelectron spectroscopy characterization and leaching experiments.The results indicated that the rest potential of magnetite was 321 mV,which was more anodic than 223 mV of arsenopyrite,and the galvanic current was 7.40μA,verifying the existence of the galvanic interaction between arsenopyrite and magnetite.The galvanic potential and polarization curves suggested that the redox behaviors of arsenopyrite dominated the overall galvanic interaction.The galvanic interaction enhanced the electrochemical dissolution of arsenopyrite with the generation of more oxidation products(S^(0),SO_(3)^(2−),SO_(4)^(2−)and AsO_(3)^(3−)) on arsenopyrite and an increase in the chemical reactivity of the surface.Leaching experiments of 6 days showed that the presence of magnetite improved the arsenic release from arsenopyrite by 30 mg/L,and further confirmed the enhanced oxidation of arsenopyrite when coupled with magnetite.

Molecular Dynamics Simulation for the Effect of Chain Length of Spacer and Tail of Cationic Gemini Surfactant on the Complex with Anionic Polyelectrolyte

Interaction of anionic polyelectrolyte with cationic gemini surfactant has been investigated by coarse-grained molecular dynamics simulation.Polyelectrolyte facilitates the oppositely charged ionic surfactants to aggregate by suppressing the electrostatic repulsion between ionic head groups leading to the formation of micellar complex.With addition of surfactant,the conformation of polyion chain changes from stretched to random coiled to spherical,and at the same time more free micelles are formed by surfactants in mixtures.Increasing the length of spacer or tail chain in gemini surfactant will weaken its interaction with polyelectrolyte and simultaneously strengthen its tendency to self-assemble.The simulation results are consistent with experimental observations and reveal that the electrostatic interaction plays an important role in the interaction of polyelectrolyte with gemini sur- factant.

Effect of Electrochemical Treatment in Aqueous Ammonium Bicarbonate on Surface Properties of PAN-based Carbon Fibers

The surface properties of PAN-based carbon fibers electrochemically treated in aqueous ammonium bicarbonate before and after treatment were characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and Dynamic Contact Angle Analysis (DCAA). The results of characterization indicated that the oxygen and nitrogen contents in carbon fiber surface were significantly increased by electrochemical treatment, and amide groups was introduced onto it, which was related with the electrolyte. The AFM photographs illustrated that the roughness of the fiber surface was also increased. The wettibality of the fibers was improved after treatment because the surface energy especially the polar part of it was increased.

Principles of Surface Potential Estimation in Mixed Electrolyte Solutions:Taking into Account Dielectric Saturation

The dielectric properties between in-particle/water interface and bulk solution are significantly different,which are ignored in the theories of surface potential estimation.The analytical expressions of surface potential considering the dielectric saturation were derived in mixed electrolytes based on the nonlinear Poisson-Boltzmann equation.The surface potentials calculated from the approximate analytical and exact numerical solutions agreed with each other for a wide range of surface charge densities and ion concentrations.The effects of dielectric saturation became important for surface charge densities larger than 0.30 C/m^2.The analytical models of surface potential in different mixed electrolytes were valid based on original Poisson-Boltzmann equation for surface charge densities smaller than 0.30 C/m^2.The analytical model of surface potential considering the dielectric saturation for low surface charge density can return to the result of classical Poisson-Boltzmann theory.The obtained surface potential in this study can correctly predict the adsorption selectivity between monovalent and bivalent counterions.

Effect of vacancy defects on electronic properties and activation of sphalerite(110) surface by first-principles

The electronic properties of sphalerite(110) surface with Zn-vacancy and S-vacancy were calculated by using density-functional theory,and the effects of vacancy defect on the copper activation of sphalerite were investigated.The calculated results indicate that surface state occurs in the band gap of Zn-vacancy sphalerite,which is from the contribution of S 3p orbital at the first layer of the surface.The presence of S-vacancy results in surface state appearing near the Fermi level and the bottom of conductor band,which are composed of S 3p and Zn 4s orbital,respectively.The surface structure of Zn-vacancy sphalerite is more stable than S-vacancy surface due to the occupation of Zn-vacancy by Cu atoms;hence,the substitution reaction of Cu for Zn vacancy is easier than the substitution of Cu for Zn atoms with S-vacancy surface.

Electrokinetic and Flotation Investigations of Surface Properties Modification of Magnesite and Serpentinite Using Biosurfactants and Surfactants

This paper presents some results of zeta potential measurements performed into biosurfactant adsorption onto magnesite and serpentinite surface. Zeta potential and isoelectric point measurement of magnesite and serpentinite particles before and after interaction with biosurfactant broth solution and activator （nickel（II） ion solution） were carried out. The zeta potential results show that presence of biosurfactants changes both magnesite and serpentinite surface potential by physical adsorption which increases the hydrophobicity of mineral particles. Measurements of particles zeta potential in the presence of biosurfactant broth are relevant to the minerals flotation. Hallimod flotation response of magnesite and serpentinite as a function of collector concentration was investigated. Bioflotation test results show that at the presence of broth, the flotation separation of magnesite from serpentinite is possible.

Preparation and surface characterization of nanodisk/nanoflower-structured gallium-doped zinc oxide as a catalyst for sensor applications

Nanostructured gallium‐doped zinc oxide （GZO） thin films were fabricated on piezoelectric sub‐strates. The GZO thin films with nanodisk/nanoflower morphologies were prepared by a simple spin‐coating process followed by one‐step hydrothermal treatment. Addition of polymer during hydrothermal treatment resulted in nanodisk and nanoflower morphologies. The morphology, microstructure and chemical composition of thin films prepared under different conditions were examined by field‐emission scanning electron microscopy （FE‐SEM）, X‐ray diffraction （XRD） and Raman spectroscopy. The XRD and FE‐SEM investigations confirmed that the GZO nanodisks, na‐norods and nanoflowers formed on the AlN/Si substrates were all wurtzite phase. Green fluorescent protein （GFP） was immobilized on the as‐synthesized GZO nanostructured materials by a dipping process. Atomic force microscopy （AFM） and fluorescence spectroscopy measurements were con‐ducted to confirm the surface binding nature of GFP on the GZO nanostructures to determine their suitability for use in sensor applications and bioimaging techniques. Trace‐level addition of GFP to the GZO nanostructures resulted in a fluorescence response, revealing good activity for ultraviolet light sensor applications.