苯乙烯-甲基丙烯酸钠共聚物在吡虫啉颗粒表面的吸附特性

通过溶液聚合合成一系列苯乙烯-甲基丙烯酸钠共聚物分散剂.研究了不同单体摩尔比对其产率和在吡虫啉颗粒表面吸附性能的影响,结果表明当两种单体摩尔比为0.8时分散剂的产率和吸附性能相对最优.通过振荡吸附实验研究了最优分散剂在吡虫啉颗粒表面的吸附动力学、等温线和热力学,由XPS近似计算不同温度下分散剂的吸附层厚度.结果表明:吸附动力学符合伪二级动力学方程;吸附等温线符合Langmuir模型;吸附热力学表明该吸附为自发、放热、熵增过程,高温不利于吸附进行;DH_ad < 40 kJ·mol^-1表明该吸附过程为物理吸附;吸附层厚度随温度升高而降低.通过与其他商品化分散剂对比可知该共聚物适合作为分散剂用于吡虫啉的水基化剂型.     

分散剂在醇-水溶液加热法制备球形 ZrO2粉体过程中的作用

本工作对分散剂在醇－水溶液加热法制备球形ZrO2粉体过程中的作用进行了研究。研究结果表明：在异丙醇－水溶液加热法制备球形ZrO2粉体时,聚合物分散剂起着明显的作用。当无分散剂加入时,所得ZrO2颗粒无规则且团聚严重;而当溶液中加入PEI（polyethyleneimine)时,可获得球形ZrO2颗粒,与加入PEI相比,加入NH4PAA或PEG所得ZrO2颗粒形状不够完整且团聚较多,这一区别可由聚合物分散剂在ZrO2颗粒上的吸附情况的不同得到初步解释。     

Dispersant-Binder Interactions in Aqueous Silicon Nitride Suspensions

The interaction of dispersant and binder on the surface of particles was studied to identify the effect of these additives on aqueous ceramic powder processing. Poly(methacrylic acid) (PMAA) and poly(vinyl alcohol) (PVA) were used as the dispersant and binder, respectively. The adsorption isotherms of the organic additives on silicon nitride were determined. The adsorption of PMAA was differentiated from PVA in the mixed additive system via ultraviolet spectroscopy. The electrokinetic behavior of silicon nitride was measured by using an electrokinetic sonic amplitude analyzer. As the PMAA concentration increased, the isoelectric point (pH_iep) of silicon nitride shifted from pH 6.7 ± 0.1 to acidic pH values. The magnitude of the shift depended on the surface coverage of PMAA. PVA did not affect the pH_iep of suspensions but did cause a moderate decrease in the near-surface potential. Finally, the rheological behavior of silicon nitride suspensions was measured to assess the stability of particles against flocculation in aqueous media; this behavior was subsequently correlated with the electrokinetic and adsorption isotherm data.     

Effect of pH on the properties of barium titanate slurries with an aniomic dispersant

The colloidal stability of barium titanate (BT) aqueous suspensions with poly(acrylamide/4‐carboxylamino‐4‐oxo‐2‐butenate) (PAAM/COB) at pH 7, 9, and 12 has been investigated by means of ζ potential, adsorption, sedimentation, and particle size measurements. The isoelectric point of BT powder is at pH 4.6 and the value of ζ potential decreases as the pH of suspensions increases. The adsorption of PAAM/COB onto BT particles follows the Langmuir adsorption isotherm. The saturated amount of adsorbed polymer decreases with increasing pH. In general, BT particles in basic solutions with PAAM/COB are more stabilized, and less agglomerated than those without any dispersant present. As pH is increased, the resulting ζ potential becomes more negative, although lower polymer concentration is required for monolayer coverage of particle surface. Consequently, the resulting suspensions become more stabilized, and contain powder with smaller particle size. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1082–1088, 2006     

Dispersion of Boron Nitride Powders in Aqueous Suspensions with Cellulose

The dispersion of nitride and carbide ceramic particles in water is difficult, due to the absence of hydroxyl groups on their surface. Boron nitride (BN) is not an exception and despite its numerous applications, no effective dispersant has been identified so far. We demonstrate here the dispersion properties of two cellulose derivatives for hexagonal BN powders, hydroxyl ethyl cellulose and methyl cellulose. The effect of particle size and cellulose concentration was investigated. The adsorption of cellulose onto the surface of the BN particles was confirmed by isotherm adsorption. Zeta potential measurements show a charge screening effect of the cellulose The suspensions obtained were highly loaded and stable versus pH, and thus could lead to homogeneous codispersion of BN particles and sintering additives.     

萘磺酸盐分散剂在不同晶型吡唑醚菌酯颗粒表面吸附性能

通过X射线衍射仪（XRD）、差示扫描量热仪（DSC）、紫外光谱（UV）、傅里叶变换红外光谱（FTIR）、X射线光电子能谱（XPS）和扫描电子显微镜（SEM）测试,研究了萘磺酸盐分散剂在两种晶型吡唑醚菌酯颗粒表面的吸附性能。两种晶型吡唑醚菌酯吸附萘磺酸盐分散剂后,晶型未发生改变;两种晶型吡唑醚菌酯吸附动力学均符合伪二级动力学方程,晶型Ⅱ E_a＝16.04 kJ·mol^-1,晶型Ⅳ E_a＝12.42 kJ·mol^-1,均为物理吸附;吡唑醚菌酯晶型Ⅱ、晶型Ⅳ吸附等温线均符合Langmuir模型,晶型Ⅱ的吸附焓变H_ad为20.64 kJ·mol^-1,吸附过程为吸热过程,温度升高有利于萘磺酸盐甲醛缩合物（D425）在晶型Ⅱ颗粒表面的吸附;晶型Ⅳ的吸附焓变H_ad为-15.26 kJ·mol^-1,吸附过程为放热过程,温度升高不利于D425在晶型Ⅳ颗粒表面的吸附。     

Influence of pH and Ionic Impurities on the Adsorption of Poly(acrylic) Dispersant onto a Zinc Oxide Surface

We have studied the properties of aqueous suspensions of ZnO powders with different purities. Our results suggest that powder purity determines the amount of dispersant necessary to form a stable aqueous suspension as well as the maximum adsorption capacity of the dispersant: the higher the positive surface charge of the as-received ZnO powders, the higher the amount of dispersant adsorbed onto the metal oxide surface. The surface charge of the ZnO particles in suspension is affected by the concentration of zinc as well as sulfate ions, which are the major impurities in the supernatant. The pH of the aqueous ZnO suspensions increases with increasing concentration of poly(acrylic) dispersant until the maximum adsorption capacity is attained. Further additions of dispersant do not increase the pH because of a buffer formation with impurity ions.     

Transport of direct dye into cellulose membrane

The dyeing process for a cellulose membrane–direct dye system is analyzed based on a parallel transport mechanism of surface and pore diffusion with Freundlich isotherm. Numerical solutions were obtained in order to clarify how the surface and pore diffusion resistances affect the uptake curve. The numerical solutions were also compared with an analytical solution for surface diffusion control to establish the range where the analytical solution can be considered as an acceptable approximation. The uptake curves in the cellulose membrane-chromophore (C.I. Direct Yellow 12) system in the presence of inorganic electrolyte were measured. The rate of adsorption and the maximum amount of adsorption increased with an increase in the concentration of those electrolytes. The rate of adsorption was approximately controlled by the surface diffusion rather than by pore diffusion. The surface diffusivities of the dye were little affected by either the concentration and or nature of the electrolyte.     

Stabilization of raw porcelain gres suspensions with sodium naphthalene sulfonate formaldehyde condensates

The stabilization of raw porcelain gres suspensions with sodium naphthalene sulfonate formaldehyde condensates (SNSFC) was examined systematically in order to understand the basis mechanism of dispersion. Small additions of SNSF to the classical deflocculating mixture with sodium silicate were tested. The repulsion between the colloidal particles was correlated with the adsorption isotherm and zeta potential. The naphthalene sulfonate condensates were effective as dispersant for raw porcelain gres suspensions. The efficiency of these dispersant was attributed to electrostatic effect between the colloidal particles. The ability of the SNSFC to stabilise stabilize raw porcelain gres suspensions was not affected by the degree of condensation.     

黑色硝化棉/乙醇油墨流变性的研究

研究了分散在硝化棉(NC)／乙醇油墨中的炭黑对油墨流变性的影响，通过Ostwald—Dewael，Mooney流变性模型分析了炭黑用量、分散剂类型及分散剂用量对黑色油墨粘度的影响，并测定了炭黑对NC的吸附等温线。     

Stabilization of PCC dispersions prepared directly in the mother-liquid after synthesis through the carbonation of (hydrated) lime

Various CaCO₃-based products are often used in the form of concentrated aqueous dispersions. This study investigates the stabilization of PCC dispersions prepared directly in the mother-liquid after the carbonation of (hydrated) lime through the adsorption of a commercial sodium polyacrylate dispersant. The results demonstrate that the composition of the mother-liquid, particularly the Ca²⁺ activity, profoundly influences virtually all processes pertinent to dispersion stabilization—from the initial charging of the CaCO₃ surface in base PCC dispersions, to the surface charge regulation and dispersion stabilization efficiency of the polyacrylate dispersing agent. Rising prominence of the counterion condensation effects in Ca²⁺ rich solutions limits the conditions conducive to the surface charge regulation through dispersant adsorption to an optimum pH range of about 8-11. Furthermore, dispersion stability analysis, based on the classical DLVO theory of colloid stability, and corroborated by experimental evidence in the form of particle size distribution analyses, also indicates that optimum stability conditions for such PCC dispersions are established with small dispersant doses (0.25-0.5% per dry weight) in the pH range of about 9-11.     

Pt、Rh及Pt-Rh合金电极上氢的吸附

The hydrogen adsorption on Pt-Rh alloys in sulfuric acid aqueous solutions was studied by the method of cathode pulses. Hydrogen adsorption on the electrode with all ratio of alloy components (ωRh = 0-100%) is well described by the Temkin logarithmic isotherm. The surface coverage by adsorbed hydrogen at the same potential is decreased with increasing content of rhodium in the system. A linear dependence of adsorption peak potential on the alloy compositions in the case of weakly bonded adsorbed hydrogen is established. Hydrogen adsorption heat as a function of surface coverage for Pt-Rh-electrodes was obtained. The shape of the current-potential curve and position of the weakly bonded hydrogen adsorption on the potential scale are all related to alloy compositions, thus can serve as the basis for the determination surface composition of allovs.     

Removal of Zinc (II) Ions from Aqueous Solutions Using Surfactant Modified Bamboo Sawdust

The present study explores the ability of surfactant modified bamboo sawdust in removing zinc (II) ions from aqueous solutions. The modified bamboo sawdust is characterized by surface area analysis, Scanning Electron Microscope, and Fourier Transform Infrared and X-ray fluorescence analysis. Adsorption isotherm and kinetic models were used to study the adsorption characteristics of zinc (II) ions onto modified bamboo sawdust. The equilibrium adsorption isotherm data were fitted into the Langmuir and Freundlich adsorption isotherms. It was found that modified bamboo sawdust yielded maximum adsorption capacity of 111.12 mg/g at 50°C for zinc (II) ions. The kinetic data obtained at different initial concentrations were analyzed using first-order-reversible reaction, pseudo-first-order, and pseudo-second-order models. The results provide strong evidence to support the hypothesis of adsorption mechanism.     

溶剂浸渍树脂吸着螺旋霉素的动力学模型研究

本文根据颗粒扩散控制机制,认为溶剂萃取过程和固体内表面的吸附同时发生,建立了有限浴条件下溶剂浸溃树脂吸着螺旋霉素的动力学模型.浸渍树脂静态吸附螺旋霉素的计算值与实验值接近,得到螺旋霉素在浸渍树脂内的有效扩散系数为3.7×10~(-12)～29.4×10~(-12)m~2/s.线性吸附等温线条件下的分析解与非线性条件下的数值解比较,表明线性假设能较好地反映实际过程.     

用椰壳制活性炭吸附去除三价铋离子(英文)

In present study,we report the preparation of coconut shell activated carbon as adsorbent and its appli-cation for Bi(Ⅲ) removal from aqueous solutions.The developed adsorbent was characterized with scanning elec-tron microscope(SEM),Fourier Transform Infrared(FTIR),C,H,N,S analyzer,and BET surface area analyzer.The parameters examined include agitation time,initial concentration of Bi(Ⅲ),adsorbent dose and temperature.The maximum adsorption of Bi(Ⅲ)(98.72%) was observed at 250 mg·L-1 of Bi(Ⅲ) and adsorbent dose of 0.7 g when agitation was at 160 r·min-1 for 240 min at(299±2) K.The thermodynamic parameters such as Gibb’s free energy(△Gθ),enthalpy(△Hθ) and entropy(△Sθ) were evaluated.For the isotherm models applied to adsorption study,the Langmuir isotherm model fits better than the Freundlich isotherm.The maximum adsorption capacity from the Langmuir isotherm was 54.35 mg?g?1 of Bi(Ⅲ).The kinetic study of the adsorption shows that the pseudo second order model is more appropriate than the pseudo first order model.The result shows that,coconut shell ac-tivated carbon is an effective adsorbent to remove Bi(Ⅲ) from aqueous solutions with good adsorption capacity.     

Adsorption characteristics of carboxymethylated lignin at a hydrophobic solid/water interface

Carboxymethylated lignin (CML), a water-soluble lignin derivative with more carboxylic groups introduced by chemical modification, can be used as dispersant in industry. In this paper, using the methods of zeta potential measurement, X-ray photoelectron spectroscopy and UV spectroscopy, natural graphite (NG) and high-purity graphite (HPG) were selected to investigate the adsorption characteristics of CML at the hydrophobic solid/water interface. The adsorption isotherm of CML on HPG was more suitable for the Langmuir model than the Freundlich model, whereas the opposite result was obtained for the adsorption of CML on NG. Moreover, the amounts adsorbed of CML on HPG increased with higher ionic strength and lowering solution pH. However, the uptake of CML on NG increased dramatically with adding NaCl under acidic condition, while the ionic strength had no obvious influence on the adsorption under neutral condition. With increasing solution pH, the amounts of CML adsorbed on NG were dropped under acidic condition followed by increases under alkaline condition. It is suggested that the interactions between CML and the minor metallic impurities on NG surface probably contribute considerably to the differences between adsorption behaviors of CML on NG and HPG in varying solution conditions. Moreover, the results showed that the adsorption mechanism of CML at graphite/water interface could be described by Lennard-Jones potential.     

含水树脂吸附剂在烃-醇二元溶液中的吸附

研究了DOO1和TS -TR树脂在非水烃 -醇溶液中的吸附 ,考察了不同水含量的两种树脂在正丁醇 -正庚烷、乙醇 -正己烷组成的二元混合溶液中的等温吸附特性 ,用NBP -a模型建立了相应的等温吸附数学模型 ,并就树脂水含量对其表面能量非均匀性的影响进行了初步研究 ,用Stieltjes变换法对树脂表面能量非均匀密度函数给出了分析解 .结果表明 ,吸附剂表面能量非均匀性及溶液非理想性是影响等温吸附的重要因素 ,极性的DOO1树脂水含量增加 ,其表面能量非均匀性增强 ,非极性TS -TR树脂水含量变化 ,其表面能量非均匀性也有明显变化 .模型拟合与实验吻合很好     

Uptake of Reactive Black 5 by pumice and walnut activated carbon: Chemistry and adsorption mechanisms

The potential of using pumice and walnut wood activated carbon as low-cost adsorbents for the removal of the diazo dye Reactive Black 5 (RB5) from aqueous solutions was investigated. The Langmuir isotherm fit to the data specified the presence of two different natures of adsorption sites with different binding energies on the AC-W surface. Kinetic modelling showed that the adsorption behaviour and mechanism of RB5 for both adsorbents is believed to happen via surface adsorption followed by diffusion into the pores of the AC-W and pumice. The main adsorption mechanisms are hydrogen bonding, electrostatic bonding and n–π interactions.     

Multilayer single-solute adsorption from dilute solutions on energetically heterogeneous solids

The isotherm equations for multilayer single-solute adsorption from dilute solutions on energetically heterogeneous solids are derived by solving the integral equation for different energy distributions and local adsorption isotherm of BET-type. This procedure is analogous to that used in multilayer gas adsorption on heterogeneous solid surfaces. The equations, obtained for quasi-gaussian energy distribution, are examined using the adsorption data of n-valeric acid, n-amyl alcohol, aniline and cyclohexanol from dilute aqueous solutions on different types of carbon adsorbents of specific surface areas from 18.4m₂/g to 124m₂/g. The best equation for describing the above data is the modified Langmuir-Freundlich one, denoted in the paper by k-LF equation.     

Adsorption of trivalent chromium from aqueous solutions onto activated carbon

The adsorption of chromium (III) onto activated carbon was investigated as a possible alternative method for its removal from aqueous solutions. The adsorption data were obtained in a batch adsorber and fitted the Langmuir adsorption isotherm well. The effect of pH on the adsorption isotherm was investigated at pH values of 2, 4, 5 and 6. It was found that at pH values below 2 the Cr(III) was not adsorbed and at pH values above 6.4 the Cr(III) was precipitated as Cr(OH)₃. Maximum adsorption occurred at pH 5. The pH plays a very important role in the adsorption of Cr(III) since Cr(III) can form different complexes in aqueous solutions. The adsorption capacity was increased by about 20% as the temperature was raised from 25 to 40°C. It was concluded that Cr(III) is adsorbed to an appreciable extent on activated carbon and that the adsorption is highly dependent upon pH.