碳酸钙疏水改性及性能表征

采用单一改性剂油酸、硬脂酸、二甲基硅油及复合改性剂对碳酸钙颗粒进行疏水改性。介绍了改性碳酸钙的作用机理。探讨了改性剂种类和加入量对碳酸钙颗粒表面疏水程度的影响,并通过活化度表征疏水程度。采用红外光谱仪表征改性前后碳酸钙的结构,说明改性剂被引入到了碳酸钙颗粒表面上;采用Zeta电位仪测定改性前后碳酸钙随pH变化的Zeta电位,得知改性碳酸钙的Zeta电位受pH影响比较大;采用激光粒度仪测定改性前后碳酸钙的粒径,得知改性碳酸钙比未改性碳酸钙的平均粒径小,且其分散稳定性要优于未改性碳酸钙。该研究也提供了随改性剂种类和加量变化来调整颗粒表面疏水程度的方法,有一定实际意义。     

原位改性法由氟硅酸废水制备纳米沉淀白炭黑

以氟硅酸废水和氢氧化铝为原料通过化学沉淀法制备了沉淀白炭黑,并在制备过程中加入表面改性剂正丁醇对白炭黑进行原位改性。研究了正丁醇添加量对白炭黑分散性和吸油值的影响。结果表明：当改性剂的添加量为3%时,平均粒径（D 0.5）从32.3 μm减小至830 nm,比表面积（BET值）从75 m2/g增加到134 m2/g,吸油值（DBP值）从2.2 mL/g增加到3.25 mL/g。改性后的白炭黑颗粒间的斥力作用增大,团聚现象大大改善,分散更加稳定。     

醋-丙乳胶纳米建筑涂料配制及性能研究

以醋-丙乳胶为粘接剂，在传统建筑涂料配方基础上，加入经表面处理的纳米TiO2、SiO2，制得了醋-丙乳胶纳米建筑涂料。探讨了纳米TiO2、SiO2平均粒径对涂膜耐人工老化性能的影响，研究了纳米TiO2、SiO2及其混合体添加量对制得的建筑涂料性能的影响。研究结果表明．TiO2、SiO2粉体平均粒径在200nm以下，涂膜的耐人工老化性能有很大改善。在100nm以下，涂膜耐人工老化性能较为理想，且加入纳米混合粉体涂膜的耐人工老化性能最佳；纳米粉体质量分数在2．0％～3．0％范围内．涂膜综合性能较佳，且能较好地满足外墙建筑涂料技术指标要求。     

Synthesis of calcium carbonate–chitosan composites via biomimetic processing

The crystal growth of calcium carbonate on a chitosan substrate was achieved using a supersaturated calcium carbonate solution, at different concentrations of polyacrylic acid (PAA) as an additive. Several techniques have been employed to characterize the systems. The pH of the solution as the one of indices was used to monitor the crystallization. In the absence of polyacrylic acid, the pH of the solution changed from 6.00 to 8.50 during the crystallization; meanwhile, sporadic nucleation and crystallization was observed via optical microscopy. By introducing polyacrylic acid to the systems, positively charged protonated nitrogen and negatively charged carboxylate ions were produced by reaction between the amino group in chitosan and the carboxyl group in polyacrylic acid, which were detected by ATR-IR and XPS techniques. These charges induced calcium carbonate nucleation of calcite and vaterite crystals on the chitosan-film surface. The average size of the vaterite phase was about 15 nm, determined by XRD. The pH of the solution changed from 5.80 to 9.25 during the crystallization; moreover, the crystals showed spherical morphology, which consisted of a large number of small particles with a diameter of about 0.2 μm. © 1995 John Wiley & Sons, Inc.     

Effect of Silica Nanoparticle Size on the Stability of Alumina/Silica Suspensions

The influence of the addition of silica particles (5, 15, 25, and 300 nm) on the zeta potential and viscosity of aqueous alumina slurries (250 nm particles) was investigated in a pH range where the surface charge was positive for alumina and negative for silica. For slurries formulated with the smaller silica particles, the isoelectric point shifted from pH 9.0 to pH ∼3 (depending on the particle size of the silica) with increasing volume fraction of silica particles. At pH 9, the original isoelectric point for the alumina alone, these mixed slurries had a shear-rate-independent, low viscosity (Newtonian behavior). Both of these results show that the smaller (≤25 nm) silica particles adsorb to the surface of alumina. The fraction of silica adsorbed to the alumina surface was dependent on the size of the silica particles, and was consistent with surface coverage calculations based on the effect of surface curvature on the limits of dense random parking. The larger silica particles (300 nm) could not physically cover the surface of the alumina particles, and simply formed a mixed, attractive particle network that exhibited a much higher viscosity with non-Newtonian (viz., shear rate thinning) behavior.     

表面活性剂对水性油墨胶体稳定性的影响

对阳离子、阴离子、两性和非离子表面活性剂对水性油墨胶体稳定性的影响进行了探讨。结果表明:(1)在水性油墨胶体溶液中加入十六烷基三甲基溴化铵(CTAB)浓度为0.14 mmol/L时,Zeta电位由初始的-37.9 mV变为12.7 mV;当CTAB浓度为0.86 mmol/L时,Zeta电位上升到34.1 mV。pH对CTAB的作用效果有较大影响,当CTAB浓度为0.5 mmol/L时,将体系pH从初始值3.3调节至11.7,Zeta电位相应地从38.6 mV降至23.7 mV,炭黑粒子的平均粒径最大增加值达13 nm。(2)加入十二烷基磺酸钠(SDS)的浓度为1 mmol/L时,Zeta电位达到-38.2 mV,而炭黑粒子的平均粒径下降了2 nm。(3)加入椰油酰胺丙基氧化胺(CAPO)的浓度为0.01 mol/L时,Zeta电位在体系pH约为6.0时达到等电点;体系pH为3.2时,Zeta电位达到最大值28.5 mV,炭黑粒子平均粒径最大增加幅度为9 nm。(4)加入脂肪醇聚氧乙烯(7)醚(AEO-7)的浓度为0.1 mol/L时,体系Zeta电位从-37.9 mV变为-16.3 mV,炭黑粒子平均粒径从初始的154 nm增至240 nm。加入AEO-9得到与AEO-7相同的影响趋势。     

Activation of blast furnace slag by a new method

Blast furnace slag is used as supplementary cementing material for the production of blended cement and slag cement. Its latently hydraulic properties can be activated by several methods. Most applications employ the use of high pH values in the pore solution (> 13.0) to accelerate the corrosion of the glass network of the slag.It is shown in this work that activation is also possible by lowering the pH to a range between 11.8 and 12.2 by the addition of calcium hydroxide and soluble calcium salts. Among the salts investigated in this study are calcium chloride, calcium bromide, calcium nitrate, calcium formate, and calcium acetate. Other salts can be used alternatively as long as they are able to increase the calcium ion concentration and thus reduce the pH in the pore solution via the calcium hydroxide equilibrium. Complex formation of organic anions with calcium ions in the pore solution is a serious handicap when using organic calcium salts.This concept was tested on a particular slag improving its early compressive strength. It was possible to increase the strength of mortar bars produced from the pure slag from 3 MPa to 25 MPa after seven days by adding calcium hydroxide, calcium carbonate and calcium acetate. The early strength of slag cement containing 80% slag was increased from 6 to 16 MPa after two days by adding calcium chloride. The final strength was increased from 36 to 53 MPa after 28 days (water/cement-ratio = 0.40, 20 °C).Analytical data is included to demonstrate that application of the aforementioned concept is able to increase heat liberation and degree of slag consumption.     

Functionalizing slag wool fibers with photocatalytic activity by anatase TiO2 and CTAB modification

Anatase TiO₂ coatings prepared by solvothermal process in a neutral ethanol solution of isopropyl titanate at 160 °C have been grown on slag wool fibers (SWF) which were modified by hexadecyltrimethylammonium bromide (CTAB) in advance. X-ray diffraction patterns confirmed the coatings are of a nanocrystalline anatase structure, and scanning electron microscopy observations and energy-dispersive X-ray spectrum revealed a continuous coverage of TiO₂ formed on the fiber surfaces. The photocatalytic activity of the samples was tested by the photocatalytic degradation of methylene blue (MB) solution. The results show that CTAB modified slag wool fibers (CMSWF) are not a suitable adsorbent for MB due to their weaker negative surface charges. Anatase TiO₂ coated CMSWF display higher photocatalyst activity than anatase TiO₂ coated SWF without CTAB modification, and Anatase TiO₂ coated CMSWF are relatively stable under UV-light irradiation.     

钢渣处理酸性染料废水的研究

采用钢渣和改性钢渣为吸附剂,处理模拟酸性大红废水,探讨了钢渣粒径、吸附时间、吸附剂用量对酸性大红去除率的影响。结果表明:钢渣粒径、吸附时间、吸附剂用量对酸性大红去除率均有影响;经过简单预处理的钢渣对酸性大红的去除效果很差,对于100mL质量浓度为100mg/L的酸性大红溶液,投加80目钢渣3g,振荡40min,最高去除率为12%;经过碱改性的钢渣,对酸性大红的去除率显著提高,最高去除率可达52.5%,比同等条件下用钢渣处理酸性大红废水,去除率提高了40%。     

棕榈酸改性纳米碳酸钙的工艺研究

采用从漆蜡中提取的棕榈酸作为表面改性剂,以活化度作为改性效果主要评价指标,对纳米碳酸钙粉体进行表面改性处理,确定了最佳改性工艺条件。对改性前后碳酸钙粉体的接触角、吸油率、石蜡糊粘度、粒度分布、分散性等性能进行了比较。结果表明,经棕榈酸表面改性处理后的纳米碳酸钙粒度分布均匀,分散性、亲油性好。     

Ca-P-H2O系电位-pH图的研究

黄磷炉渣是采用磷矿、硅石、焦炭通过电炉法经1400-1600℃高温还原生产黄磷时得到的固体废弃物,具有很高的反应活性,其主要成分为硅、钙元素的化合物,采用磷酸浸取时可反应生成水合二氧化硅和可溶性钙盐,以实现硅钙分离,制取有价产品.文中通过热力学计算,绘制了298.15 K下Ca-P-H2O系的电位-pH图,并通过分析发...     

Highly efficient green synthesis of highly pure microporous nanosilica from silicomanganese slag

Highly pure nanosilica was synthesized through a facile hydrometallurgy-based method from silicomanganese slag as a low cost silica source. The synthesis route included short-term nitric acid dissolution at room temperature, gelation, washing, drying, and calcination steps. The experimental dissolution conditions resulted in a dissolution efficiency of 98%. The crystalline structure, chemical composition, chemical bonding, microstructure and elemental analyses, particle size distribution, and surface area of the extracted silica were then studied by appropriate characterization techniques. The characterization findings indicated that the amorphous silica particles had a microporous nature with an average particle size of ~24 nm, exhibiting a high purity of more than 99% and a high specific surface area of ~474 m² g^?1. The overall results indicated that the proposed synthesis route is a promising feasible alternative method to produce highly pure microporous nanosilica from a low cost secondary resource. The proposed method can treat 98% of the slag and uses less chemicals than conventional methods and is therefore a greener nanosilica production process. The current process also competes with the traditional process and other recently introduced processes in terms of process economy and the quality of the produced product.     

改性镍铁渣吸附剂对Cr(VI)吸附性能的影响及机理分析

以镍铁渣为原料,加入硝酸和表面活性剂对其矿物相改性,制备改性镍铁渣吸附剂,考察表面活性剂种类、十六烷基三甲基溴化铵(CTAB)掺量、吸附剂掺量、溶液初始pH值、Cr(VI)浓度对Cr(VI)吸附效果的影响。结果表明:镍铁渣经改性后可制得结构疏松、比表面积高达180.6 m²/g的无定形SiO₂;改性镍铁渣对Cr(VI)的吸附率在10 min内可达到90%,吸附等温线符合Langmuir模型,最大理论吸附容量为42.55 mg/g,吸附动力学符合拟二级动力学模型。改性镍铁渣吸附剂对Cr(VI)的吸附机理主要是物理吸附和氧化还原,即吸附剂表面范德华力将HCrO ^-₄吸附至吸附剂表面,CTAB提供的电子对将Cr(VI)还原为Cr(III)。对镍铁渣改性获得的高比表面积无定形SiO₂不仅可以有效吸附净化Cr(VI),同时可以实现镍铁渣资源化利用,达到以废治污的目的,具有良好的环境效应和经济效益。     

Optimization of milling parameters on the synthesis of stearic acid coated CaCO3 nanoparticles

Surface modification of precipitated calcium carbonate particles (calcite) in a planetary ball mill using stearic acid as a modification agent for making dispersion in hydrocarbon oil was investigated. Different parameters for processing (milling) such as milling time, ball-to-sample ratio, and molar ratio of the reactant were varied and analyzed for optimization. The physical properties of the hydrophobically modified calcium carbonate particles were measured; the particle size and morphology of the resulting samples were characterized by transmission electron microscopy and X-ray diffraction. The surface coating thickness was estimated using small angle X-ray scattering.     

The effect of SiO_2 particle size on iron based F–T synthesis catalysts

The effect of particle size of silica, as catalyst binder, on the chemical and mechanical properties of iron based FT catalyst was studied in this work. The samples were characterized using XRD, BET, TEM, FT-IR, and H2-TPR, respectively. The attrition resistance and the FT activity were tested. Si-8–Si-15 catalysts prepared with 8–15 nm silica sol show good attrition resistance(attrition loss b 4%), especially Si-13 with an attrition loss of 1.89%. Hematite appeared in XRD patterns when silica sol above 15 nm is used. TEM micrographs show that no obvious Si O_2 particles appear when silica sol particle with size less than 8 nm was used, but Si O_2 particles coated with small ferrihydrite particles appear when silica sol above 8 nm was used. Si–O–Si vibration peak in FT-IR spectra increases with increasing silica sol size. Samples prepared with silica sol show good stability of FT reactions, and the average molecular weight of FT products increases with the increase of Si O_2 particle.     

加压碳化体系对纳米碳酸钙粒度和分散性的影响

利用加压碳化体系制备粒径均一、高分散性纳米碳酸钙材料。考察氢氧化钙浓度、表面活性剂添加量、反应温度、CO2压力对制备纳米CaCO3粒子尺寸和分散程度的影响,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、Zeta电位和傅立叶变换红外光谱(FT-IR)对制备的纳米碳酸钙粒子进行表征。结果表明,最优加压碳化反应条件是Ca(OH)2质量浓度为2%、表面活性剂添加量为3%(占碳酸钙理论产量的百分比)、反应温度为40℃、CO2压力为6 MPa,所得立方形碳酸钙平均粒径为117 nm,晶型为方解石型碳酸钙。碳化反应加入表面活性剂十六烷基三甲基溴化铵(CTAB)使CaCO3表面形成的正电荷增大至+37.7 mV并高于标准值30 mV,表明制备的CaCO3产品具有良好的分散性且稳定。通过FT-IR和Zeta电位对CTAB改性前后CaCO3纳米粒子进行表征,探讨了CTAB对合成纳米CaCO3分散性的影响机理,为纳米碳酸钙制备提供了一种新的方法。     

蜂巢石改性及其对Mn~(2+)吸附试验研究

为探讨硫酸对蜂巢石吸附材料改性的影响因素,以及改性蜂巢石对Mn~(2+)的吸附特性,采用正交试验法研究了硫酸改性条件对蜂巢石比表面积、孔容、孔径的影响;对改性蜂巢石和未改性蜂巢石做了SEM和XRD对比分析;通过静态吸附试验探讨了硫酸改性蜂巢石对Mn~(2+)的最佳吸附条件。试验结果表明,硫酸浓度为0.50mol/L,改性时间为30 min,温度为35℃时改性最佳,改性后蜂巢石比表面积、孔容分别达到21.15 m2/g、0.053cm3/g左右,平均孔径为5 nm;SEM和XRD对比分析发现,改性后蜂巢石表面变得粗糙蓬松,微孔增加,空隙率和孔道通透性提高,出现了Ca SO4·2H2O单斜晶体;改性蜂巢石投加量和溶液的p H值是影响吸附效果的重要因素,当溶液p H值为5,改性蜂巢石投加量为4 g/L,Mn~(2+)初始质量浓度为5 mg/L时,对Mn~(2+)的去除率达85%以上,吸附量超过10.0 mg/g。     

荧光胺定量检测纳米SiO2表面氨基的含量

首先用3-氨丙基三乙氧基硅烷偶联剂(APTES)在一定条件下接枝于纳米二氧化硅表面,并采用傅里叶变换红外光谱仪(FI-IR)进行测试表征,建立了一种用荧光胺定量检测功能化纳米SiO2表面氨基的方法,并通过优化实验建立该检测方法的测试标准.最佳检测条件为:室温下,激发波长380 nm、发射波长480 nm,荧光胺的丙酮溶液与磷酸盐缓冲液体积比1:5,磷酸盐缓冲液pH值为10.0,反应时间为10 min等条件下,荧光信号最稳定.采用该最佳条件下制定的标准曲线对功能化纳米SiO2微球进行检测,结果符合预期,该方法检测灵敏度高、操作简单.     

Development of antifouling properties and performance of nanofiltration membranes modified by interfacial polymerisation

Two types of bisphenol monomers, Bisphenol A (BPA) and Tetramethyl Bisphenol A (TMBPA), with different concentrations of bisphenol aqueous solution (0.5% to 2.%w/v) and various interfacial polymerisation times (10 s, 30 s and 60 s) in the fixed 0.15%w/v organic solution of trimesoyl chloride (TMC)-hexane were studied. Irreversible fouling of both unmodified polyethersulfone NFPES10 and modified polyester thin-film composite polyethersulfone membranes were studied using humic acid model solutions at two different pH values, pH 7 and pH 3. It was observed that polyester thin-film composite membranes prepared by BPA exhibited fewer tendencies for irreversible fouling by humic acid molecules at neutral environment compared to unmodified NFPES10 and TMBPA-polyester series. This is most probably due to high electrostatic repulsion force between negatively charged of BPA-polyester layer and highly negative charged of humic acid at pH7. However, some modified membranes with rougher surfaces were severely fouled by humic acid molecules at acidic environment, pH 3. Under this acidic environment, carboxylic acid groups of humic acid lost their charge and the macromolecules of humic acid have smaller macromolecular configuration due to the increased hydrophobicity and reduced inter-chain electrostatic repulsion. Thus the molecules of humic acid may be preferentially accumulated at the valleys of the rougher membrane surface blocking them and resulting in a more severe fouling. In addition, the modification also affected membrane pore size and pore size distribution as shown by AFM images. It was also observed that the smaller pore size generated after modification does not have significant effect on humic acid removal due to the larger size of humic acid molecules. All the modified membranes posses smaller pore size than the unmodified NFPES10 (1.47 nm) in the range of 0.8–1.34 nm.     

MWNTs or PEG as Stability Enhancers for DNA–Cationic Surfactant Gel Particles

Cationic surfactants interact with DNA (Deoxyribonucleic acid), forming surfactant-DNA complexes that offer particularly efficient control for encapsulation and release of DNA from DNA gel particles. In the present work, DNA-based particles were prepared using CTAB (Cetyltrimethylammonium bromide) as the cationic surfactant and modified using two different additives: (Multi-Walled Carbon Nanotubes) MWNT or PEG (Poly Ethylene Glycol). The use of both additives to form composites increased the stability of the gel particles. The stability was monitored by the release of DNA and CTAB in different pH solutions. However, not much is known about the influence of pH on DNA–surfactant interaction and the release of DNA and surfactant from gel particles. It was observed that the solubilization of DNA occurs only in very acid media, while that of CTAB does not depend on pH and gets to a plateau after about 8 h. Within 2 h in contact with a pH = 2 solution, about 1% DNA and CTAB was released. Complete destruction for the gel particles was observed in pH = 2 solution after 17 days for PEG and 20 days for MWNT. The composite particles show a considerably enlarged sustained release span compared to the unmodified ones. The dehydration-rehydration studies show that the structure of the composite gel particles, as determined from SAXS (Small-Angle-X-Ray-Scattering) experiments, is similar to that of the unmodified ones. These studies will allow a better knowledge of these particles’ formation and evolution in view of possible applications in drug delivery and release.