无机电解质对有机染料水分散体稳定性及动电性质影响研究

本文制备了不同浓度的阴离子表面活性剂或非离子表面活性剂—分散染料(C.I.分散蓝79)水分散体系,并以沉降度作为分散体的稳定参量,动电位为颗粒电结构参量,研究了无机电解质对这些分散体的稳定性和动电性质的影响。动电性质实验和沉降实验良好符合。结果表明,较低浓度的无机电解质能辅助扩散双电层的建立从而增加分散体稳定性;当其浓度超过某临界值时又会压缩双电层从而成为不稳定因素。尽管电解质浓度增大使表面活性剂在染料颗粒表面吸附量增大,但电解质对双电层的直接影响始终占主导地位。     

表面活性剂HLB值对炭黑色浆分散稳定性的影响

考察了表面活性剂的亲水疏水平衡值(HLB)及添加量对色浆中炭黑润湿、分散及稳定性的影响,借助等效润湿接触角法、润湿热法、分散函数、稳定函数法和理想化模型法等对色浆体系稳定性进行了评价,并对稳定机理进行了分析. 结果表明,无论是引入单一型表面活性剂还是复配型表面活性剂,只有当体系的HLB值与炭黑的HLB值接近时,才能达到良好的润湿、分散与稳定效果;复配表面活性剂对炭黑分散效果优于单一型表面活性剂;阴离子与非离子表面活性剂复配的分散效果明显优于非离子与非离子表面活性剂复配;添加5.0wt%表面活性剂时体系分散稳定性最佳;基于吸附层理论与结合力理论较好地解释了表面活性剂存在最佳HLB值和添加量的原因.     

活性剂对颜料的分散及稳定性的研究探讨

离子型活性剂能在水溶液中电离出大量带电的离子,牢固地吸附在颜料粒子的表面,并具有相同电荷,其它带相反电荷的离子则自由扩散到液体介质的周围,形成一个带电离子的扩散层。这些带相同电荷的粒子一经接触就相互排斥,从而保持分散体系的稳定。因为表面活性剂能够定向地吸附在颜料粒子的表面,形成一种单分子吸附层,这种定向缓冲层能防止粒子间的相聚,从而保持分散体系的稳定。本文采用溶液吸附法加入离子型和非离子及高分子量的表面活性剂,在颜料的表面上形成吸附层,经过反复实验后,选择出了一种分散性能较为理想的的表面活性剂,改善了涂料贮存方面的缺点,并使涂膜便于在底材上展布,降低了涂料的生产成本和提高了生产效率。     

非离子型表面活性剂对氯乙烯-水界面张力和保胶能力的影响

以聚乙烯醇/羟丙基甲基纤维素(KH20/60SH50)为主分散剂.非离子表面活性剂Span 60为助分散剂,考察氯乙烯悬浮聚合中油-水界面张力和保胶能力随非离子表面活性剂浓度的变化,发现非离子表面活性剂降低界面张力的能力和效率都强于主分散剂,但界面保胶能力不如后者;从Gibbs界面吸附公式和R值理论出发建立非离子表面活性剂、主分散剂在油-水界面上的竞争吸附模型,认为主分散剂/助分散剂混合使用时,助分散剂优先吸附于界面,在降低界面张力的同时也使分散体系保胶能力下降.     

非离子表面活性剂作用下分散染料对棉沾色机理研究

通过研究非离子表面活性剂结构和浓度对C.I.分散红60增溶量、分散体系的高温稳定性、C.I.分散红60的上染率以及染浴中染料残留量的影响,探讨了在非离子表面活性剂作用下C.I.分散红60对棉沾色的机理。结果表明:非离子表面活性剂用量较低(0.5 g/L左右)时,分散体系有较好的高温稳定性,此时非离子表面活性剂对分散染料的增溶量为影响沾色的主要因素,分散染料的增溶有利于减少其对棉的沾色;随着非离子表面活性剂用量的增加(≥1 g/L),染料的上染百分率和分散体系的高温稳定性降低,分散染料对棉的沾色加重,沾色等级降低到2级。     

表面活性剂对复合镀(Ni-P)-MoS_2中MoS_2颗粒分散性的影响

选取阳离子表面活性剂十六烷基三甲基溴化铵、全氟辛基季铵碘化物、非离子表面活性剂聚乙二醇以及阴离子表面活性剂全氟辛酸磺酸钾。研究了不同类型的表面活性剂的复配对化学复合镀(Ni-P)-MoS2中MoS2分散性的影响。结果表明,阳离子与非离子表面活性剂之间的协同作用,有利于MoS2纳米颗粒的分散,可以提高(Ni-P)-MoS2复合镀层的质量。     

7003铝合金CMP后表面SiO2纳米颗粒清洗研究

通过在弱酸环境的水溶液条件下加入非离子表面活性剂辛基苯基聚氧乙烯醚,缓蚀剂焦磷酸二氢二钠和苯并三氮唑(BTA),并结合超声波的湿化学清洗方法,对化学机械抛光(CMP)后的7003铝合金表面的清洗进行了研究.利用扫描电子显微镜(SEM)和原子力显微镜(AFM)对清洗前后铝合金表面形貌进行对比分析.研究结果表明,辛基苯基聚氧乙烯醚能够保持颗粒和表面之间处于容易清洗的物理吸附状态,结合超声波协同作用可以对铝合金表面残留的SiO2颗粒进行有效的清洗.在一定范围内随着活性剂质量分数的递增,表面清洗效果逐渐改善,当质量分数为2%时,表面残留的SiO2颗粒基本被清洗干净,得到最优表面且未发生腐蚀现象.清洗后表面形成活性剂保护层,防止了颗粒的再次吸附.     

液体分散染料的制备

制备了含有普通结构的阴离子或非离子分散剂的 C.I.分散蓝79(即分散青 S-2GL)的高浓水分散体系.并通过测定这些体系的沉降性质、染色性能、颗粒分布、动电性质及直接观察颗粒絮凝情况,对该染料液态剂型配方进行了初步选择,并就沉聚机理、表面活性剂和无机电解质对分散体系稳定性的影响等有关理论提出了解释.     

复配表面活性剂对铜CMP后清洗中颗粒的去除

选用阴离子表面活性剂脂肪醇聚氧乙烯醚硫酸钠(AES,体积分数0.1％)和非离子表面活性剂异辛醇聚氧乙烯醚(JFC-E,体积分数0.25％)复配的清洗液(pH=10.3)去除铜布线化学机械抛光(CMP)后表面残留的SiO2颗粒.研究了2种表面活性剂的体积比对复配溶液的润湿性能、在铜表面的吸附情况、清洗效果和对清洗后铜表面状态的影响.结果表明,按AES和JFC-E的体积比2:3复配的清洗液具有最佳的润湿性能和吸附效果,并且对颗粒的去除效果最好,对铜表面状态的影响最小.     

纳米TiN粉末在水溶液和无水乙醇中的分散行为

通过粒径和颗粒表面电性质的测定,探讨了纳米TiN粉末在水溶液和无水乙醇中的分散特性及表面活性剂对分散的影响. 实验结果表明,纳米TiN颗粒在水中分散,溶液的pH值对颗粒的分散性有很大的影响,在pH 8处,能得到最好的分散效果. 随pH值变化,颗粒表面的荷电性质从正变化为负,等电点为3.7. 其分散行为遵循双电层静电稳定机制. 纳米TiN颗粒在无水乙醇中的分散行为受pH值的影响相对较小. 在整个pH范围内,颗粒表面荷正电,颗粒表面的溶剂化作用对分散起主导作用. 表面活性剂聚氧乙烯十二烷基醚可作为纳米TiN颗粒在水溶液中分散的分散剂,聚乙二醇可作为在水溶液和无水乙醇中分散的分散剂.     

A new dye‐modified poly(ethylene oxide)–poly(propylene oxide) polymer used as a dispersant for CI Disperse Red 60

A new dye‐modified poly(ethylene oxide)–poly(propylene oxide) polymer, in which the dye molecule (CI Disperse Red 60) is bonded onto polyether monoamine via a triazine ring, was synthesised for the preparation of dye aqueous dispersions and was characterised by Fourier Transform‐infrared spectroscopy, ¹H nuclear magnetic resonance spectroscopy and elemental analysis. This polymer exhibits unique dispersing performance for CI Disperse Red 60. The mechanism behind the improved performance is briefly discussed with the help of adsorption isotherms. The results indicated that the hydrophobic dye group of this polymer can strongly adsorb onto the dye particle surface through π–π interaction while its long hydrophilic poly(ethylene oxide) chains allow the formation of a thick layer around the dye particles. It was speculated that the adsorbed polymer molecule on the dye surface would form a brush‐like monolayer conformation. The dyeing performance of the prepared dye dispersions on polyester fabrics was also investigated. It was found that this polymer can effectively increase the apparent solubility of disperse dye. The dyed fabrics showed very good to excellent fastness to washing and rubbing, while the dyeing effluent was colourless.     

Stability of Dye Dispersions in the Presence of Some Eco-Friendly Dispersing Agents

The stability of dye dispersions in the presence of ethoxylated sorbitan lauryl and oleyl esters were reported and compared with dye dispersions containing a conventional dispersing agent, i.e. naphthalene sulfonic acid methylene-bis sodium salt (NSAB). The optimum operating conditions obtained using a central composite design and stability of dye dispersions were evaluated by a turbidimetry method. Results showed that the dose of surfactants and the temperature of operation were important factors in preparing stable dye dispersions. Also, the best conditions for preparing dye dispersions were as follows: dose of surfactant 0.05 g, temperature 25 °C and time 5 min. In addition to, findings indicated that both of the used surfactants had better performance in dispersing the dyes in water. However, ethoxylated sorbitan oleate had better efficiency relative to other used dispersing agents. The performance of both sorbitan esters were compared with NSAB. The results indicated that they can create stable dye dispersions in aqueous media and have approximately the same effectiveness with NSAB. In this series, although oleate ester had a better performance than the laurate, the difference in performance of using dispersing agents was not significant. This finding was confirmed by the results of the particle size analysis of dye dispersions.     

Dispersion characteristics of magnetic particles: Surface charge, surface adsorption and acid-base interaction behavior

Electrophoretic mobility (EM) of magnetic oxide particles has been measured in aqueous as well as organic solvent media using a zeta meter and a mass transporter analyzer. EM has also been measured for the magnetic particles after treatment with surface active compounds and/or in the presence of a surfactant. The results show that the sign and magnitude of the EM values change depending on the type and polarity of the surfactants or surface-treating compounds. The sign reversal of the EM values when the medium is changed from water to organic solvent can be understood on the basis of acid-base interaction. The potential energy between particles calculated using the maximum available EM value in an organic solvent is far below the value required for dispersion stability. These results along with the calculation o magnetic potential energy show that the stability of these dispersions cannot be maintained by electrostatic potential alone. Treatment of these oxide particles with surface active compounds provide stable dispersions by a ‘stearic stabilization’ mechanism. Adsorption of surfactants such as organic phosphate compounds and binder resins such as nitrocellulose or polyurcthanes on magnetic oxide particles is due to acid-base interfacial interaction between oxide particles, organic macromolecules, and solvents. Adsorption of these macromolecules in multilayers seems to be a major cause for high dispersion viscosity and the poor magnetic properties of these dispersions on tapes. These results indicate flocculation of the particles, possibly by a bridging mechanism. Thus, surface treatment of oxide particles with proper compounds inhibits adsorption of the binder resins in multilayers, promotes better rheological properties of the formulated grinds, and improves magnetic performance of tapes coated with these grinds.     

The influence of adsorbed layers on the rheological behavior of titanium dioxide dispersions

The aim of this study is to relate the influence of stearic acid on the rheological behaviour of titanium dioxide dispersions in alkyd resin solutions to the composition of the adsorbed layer on the dispersed particles.The adsorption of alkyd resin was studied using gel permeation chromatography. From the differences occurring in the molecular size distributions of the initial resin and the residual resin after adsorption, it followed that the adsorbed molecules extended throughout the whole molecular size distribution with a maximum at an equivalent chain length of 2800 Å.Stearic acid adsorption — determined using a radioactive tracer technique — was reduced by the presence of alkyd resin in the system.Titanium dioxide dispersions in alkyd resin solutions exhibited Newtonian rheological behaviour, showing that the adsorbed resin molecules protected the dispersed particles very well against flocculation. By counteracting the alkyd resin adsorption, the presence of stearic acid in the systems induced flocculation, leading to Bingham rheological behaviour. A direct relationship was shown to exist between the obtained Bingham yield values and the stearic acid adsorption.     

The effect of surfactants on peat dewatering

The effect of cationic, anionic and neutral surfactants on the mechanical dewatering of a highly decomposed fuelgrade peat has been examined. Surfactant adsorption and zeta potential of the peat particles correlated with dewatering of peat samples. The cationic surfactants had large positive effects on dewatering, the anionic surfactants had a negative effect while the neutral surfactant had no effect. The effects of the surfactants could be explained by charge neutralization and double layer suppression. The cationic surfactants were superior to analogous organic salts because of enhanced interaction by the hydrophobic effect.     

Stability of kaolinite dispersions in the presence of sodium and aluminum ions

The stability of colloidal kaolinite dispersions in the presence of NaCl and AlCl₃ was studied by measuring turbidity, electrophoretic mobility and adsorption. The kaolinite particles coagulated at pH 2.5–3.5 and were dispersed at pH >4.5. These results well obeyed the classic DLVO theory if the mean zeta potential of the kaolinite particles in aqueous solutions was taken into account in the computation of potential energy of electrical double layer repulsion, which suggests that the kaolinite particles might coagulate in the same way as normal colloidal particles. The kaolinite particles in aqueous aluminum salt solution only coagulated at a medium AlCl₃ concentration, and formed a stable dispersion at a high salt concentration. This is caused by Stern-layer adsorption of hydrolyzed aluminum species, probably adsorbed on the kaolinite surfaces through hydrogen bonds between the hydroxyl groups of the aluminum species and the oxygen atoms on the kaolinite surfaces.     

Adsorption of dyes to cotton and inhibition by surfactants, polymers and surfactant–polymer mixtures

A wide-ranging investigation has been made of the adsorption of direct dyes to cotton and of inhibition by surfactants, polymers and polymer–surfactant mixtures. Generally, the selected polymers are extremely effective at inhibiting adsorption of most of the direct dyes to cotton but are less effective at inhibiting adsorption of small, model azo dyes. Micellar solutions of zwitterionic and cationic surfactants can inhibit adsorption of both small dyes and commercial dyes. It is shown that anionic surfactants at sub-micellar concentrations can inhibit polymer-dye interactions due to displacement of dye and/or relocation into micelle-like polymer–surfactant complexes. New insights have been obtained into the interactions of dyes with cotton and with polymers, surfactants or their mixtures, particularly into observed dye selectivities.     

The adsorption behavior of dialkyl dimethyl ammonium chloride-nonionic surfactant binary systems

From the practical standpoint of fabric softener formulation, a comparative study was made on adsorption behavior toward fabrics of binary systems consisting of di(hydrogenated tallow) dimethyl ammonium chloride (purified Arquad 2HT) and typical polyoxyethylenated nonionic surfactants which are commonly used as auxiliary agents for softeners. Soxhlet extraction of treated fabrics and quantitative analysis by high-performance liquid chromatography (HPLC) gave significant results indicating many of these nonionic surfactants, assumed to be inherently unadsorbable in rinse-cycle treatment, were highly adsorbable even at a high bath ratio by being applied with the water-insoluble cationic surfactant. Moreover, it was also disclosed that the hydrophobic structure of nonionic surfactants is another factor, other than hydrophobicity, determining adsorption. Furthermore, the mechanism of this nonionic adsorption was elucidated on the basis of results of structural analyses of binary dispersions by differential scanning calorimetry (DSC), X-ray diffraction, electron spin resonance spectroscopy (ESR) and transmission electromicroscopy (TEM) in addition to partition measurements of the surfactants into the dispersed and the continuous aqueous phases. It was concluded that the primary driving force for this nonionic adsorption is an association with the lamellar of Arquad 2HT and that the cationic vesicles act as “anchors” in adsorption.     

Evaluations of physico-chemical properties of TiO2/clinoptilolite synthesized via three methods on photocatalytic degradation of crystal violet

Different preparation routes for Ti O_2-supported natural and synthetic clinoptilolite(Ti O_2/CP) composites were thoroughly investigated on the basis of sol–gel, hydrothermal, and in-situ hydrothermal methods.The micro-structural features and physicochemical properties of resultant Ti O_2/CPs were characterized via X-ray diffraction patterns, scanning(transmission) electron microscope images, Fourier transform infrared spectra, inductively coupled plasma-optical emission spectrometry methods, BET-isotherms,UV–visible spectra, and surface charge potential distributions. The results showed that in-situ hydrothermal method led to well dispersions of loaded-Ti O_2 particles on the surface of leaf-like CP, while obviously aggregated Ti O_2 on a relatively distorted structure of CP was obtained using sol–gel and hydrothermal methods. Their adsorptive and photocatalytic efficiencies for removal of crystal violet(CV) dye in aqueous solution were also explored under UV-irradiations. The results demonstrated that Ti O_2/CPs synthesized via sol–gel and in-situ hydrothermal methods presented the excellent performances with 98%removal efficiencies as compare to the bare commercial Ti O_2 which achieved 53% removal of CV dye.While, the in-situ hydrothermally synthesized Ti O_2/CPs were the best due to their moderate energy cost,highest adsorption capacities and removal efficiencies. Particularly, the synthetic CPs as supports exhibited synergetic photocatalytic activities for the degradation of CV dye, which is attributed to their high surface areas, better adsorption capability, and fine dispersion of Ti O_2 particles. Adsorption and degradation kinetics of CV dye were found to follow the pseudo-second and pseudo-first order models,respectively.