Formation of macroporous gel morphology by phase separation in the silica sol-gel system containing nonionic surfactant

The phase separation and gel formation behavior in an alkoxy-derived silica sol-gel system containing C₁₆EO₁₅ has been investigated. Various gel morphologies similar to other sol-gel systems containing organic additives were obtained by changing the preparation conditions. Micrometer-range interconnected porous gels were obtained by freezing transitional structures of phase separation in the sol-gel process. The dependence of the resulting gel morphology on several important reaction parameters such as the starting composition, reaction temperature and acid catalyst concentration was studied in detail. The experimental results indicate that the gel morphology is mainly determined by the time relation between the onset of phase separation and gel formation.     

Development of high volume rice husk ash alumino silicate composites

The development of high volume rice husk ash (RHA) alumino silicate composites (ASC) was studied. RHA was used as the source of silica and aluminium in the ASC. The mass ratios of RHA:Al(OH)3 of 70:30 to 99:1 were tested. The results indicate that the obtained ASC mortars are not stable and disintegrate in water. Boric acid was introduced to the mixture to overcome this problem. Stable ASC mortars with high RHA:Al(OH)₃ mass ratios of 90:10 to 97.5:2.5 were obtained with the use of boric acid and 115℃ curing. The compressive strength of the mortar of 20 MPa was gained. The immersion test indicates that high volume RHA ASC mortars show good resistance in 3vol% H₂SO₄ solution, but is slightly less durable in 5wt% MgSO₄ solution.     

Preparation and characterizat ion of polypropylene/silica composite particl e with interpenetrating network via hot emulsion sol–gel approach

A novel interpenetrating structural ultrafine polypropylene-silica nanocomposite particles were synthesized by a modified sol–gel approach in the presence of the melt polypropylene emulsion. A series of samples with different polypropylene content was prepared to investigate the unique characteristics of this original nanocomposite. The thermal gravimetric analysis and differential scanning calorimetry results showed that the nanocomposites had the interpenetrating structure and good thermal stability,and the crystallization behavior of polypropylene was confined by the silica matrix. The interpenetrating structure of nanocomposites was also suggested by the nitrogen adsorption–desorption measurement results. The scanning electronic microscope and transmission electron microscopy images indicated that the nanocomposites had irregular particle morphology. The nanoparticle tracking analysis results show that the mean size of the nanocomposites was around 160 nm. According to the results obtained from different measurements,a reasonable formation mechanism was proposed.     

Preparation of Cu-SiO<Subscript>2</Subscript> composite aerogel by ambient drying and the influence of synthesizing conditions on the structure of the aerogel

A copper-doped silica composite aerogel with high specific surface area was prepared using a sol-gel method at ambient pressure. A drying control chemical additive (DCCA) N,N-dimethylformamide (DMF) was introduced to the composite sol of tetraethyl orthosilicate (TEOS) and copper nitrate (Cu(NO3)2·3H2O) during the synthesizing process. The influence of the preparation conditions including Cu loading, catalyst concentration and heat treatment on the structure of copper-doped silica was investigated. The results showed that the obtained aerogel particles were uniformly distributed. The pore diameter was in a range of 2 to 15 nm. Heavier Cu loading benefited the formation of CuO crystalline, and reduced the specific surface area and pore diameter. When the catalyst concentration was high, the aggregation of Si-O network was reduced with the increase of it. The composite aerogel exhibited a good thermal stability after the heat treatment at high temperature.     

Synthesis and characterization of bifunctional terbium complex-based nanoparticles

Novel bifunctional terbium complex-based nanoparticles were developed using a modified Stber method and a layer-by-layer assembly process. A magnetic core of Fe3O4 nanoparticles was coated with a silica shell to form the first layer. Then a ternary Tb3+ complex (TESPPA-Tb), which acted as a luminescent marker, was covalently bound to the silica surface by stable Si-O-Si bonds. The TESPPA monomer was synthesized by binding pyridine 2,6-dicarboxylic acid to 3-aminopropyltriethoxysilane, which was used as a ligand for coordination with the Tb3+ ions. An outer shell of silica was applied to the nanoparticles to allow for versatility with surface functionalization. The nanoparticles were characterized by X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, ultravioletvisible spectroscopy, vibration sample magnetometer, and photoluminescence spectroscopy. The bifunctional nanoparticles exhibited favorable superparamagnetic behavior and photoluminescence properties of Tb3+. These nanoparticles have potential applications in biolabeling, bioseparation, immunoassays, and pathogenic diagnosis.     

Modified natural zeolite as heterogeneous Fenton catalyst in treatment of recalcitrants in industrial effluent

Industrial effluents with high recalcitrants should undergo post-treatment after biological treatment. The aim of this study was to use cheap and abundantly available natural materials to develop heterogeneous Fenton catalysts for the removal of colored recalcitrants in molasses distillery wastewater(MDW). The pellets of zeolite,which is naturally available in many countries, were modified by pre-treatment with sulphuric acid, nitric acid and hydrochloric acid, before embedding on them the ferrous ions. The effects of p H and temperature on heterogeneous Fenton were studied using the modified catalysts. The sulphuric acid-ferrous modified catalysts showed the highest affectivity which achieved 90% color and 60% TOC(total organic carbon) removal at 150 g/L pellet catalyst dosage, 2 g/L H_2O_2 and 25 °C. The heterogeneous Fenton with the same catalyst caused improvement in the biodegradability of anaerobic effluent from 0.07 to 0.55. The catalyst was also applied to pre-treat the raw MDW and increased it's biodegradability by 4%. The color of the resultant anaerobic effluent was also reduced. The kinetics of total TOC removal was found to depend on operation temperature. It was best described by simultaneous first and second order kinetics model for the initial reaction and second order model for the rest of the reaction.     

<Emphasis Type="Italic">In situ</Emphasis> characterization of natural pyrite bioleaching using electrochemical noise technique

An in situ characterization technique called electrochemical noise (ECN) was used to investigate the bioleaching of natural pyrite. ECN experiments were conducted in four active systems (sulfuric acid, ferric-ion, 9k culture medium, and bioleaching solutions). The ECN data were analyzed in both the time and frequency domains. Spectral noise impedance spectra obtained from power spectral density (PSD) plots for different systems were compared. A reaction mechanism was also proposed on the basis of the experimental data analysis. The bioleaching system exhibits the lowest noise resistance of 0.101 MΩ. The bioleaching of natural pyrite is considered to be a bio-battery reaction, which distinguishes it from chemical oxidation reactions in ferric-ion and culture-medium (9k) solutions. The corrosion of pyrite becomes more severe over time after the long-term testing of bioleaching.     

Synthesis and Application of Sodium Benzoylthioglycollate to Cotton Fabric

The paper discussed the synthesis and application of sodium benzoylthioglycollate (BTG) to cotton cellulose. The main product was proved to be BTG. Dyeing substantivity of modified cotton fibre by BTG with disperse dye were improved. The effect of modification conditions, such as the property of alkali and its using amount, curing temperature and time were discussed. Colour yield and resistance to wash fastness were also measured.     

Tentative Research of Short Process of Jute Degumming and Bleaching

The feasibility of combination process of jute degumming and bleaching with alkali-hydrogen peroxide in one-step-one-bath was discussed. The combination process basically has the similar function as the traditional two-step-two-bath method. The factors such as hydrogen peroxide concentration, CBI concentration, sodium hydroxide concentration, treatment time and temperature were studied respectively, and then an orthogonal experiment was designed to study the interactions among the hydrogen peroxide concentration, CBI concentration, sodium hydroxide concentration. After the designed experiments, the optimum treatment conditions were obtained as follows: hydrogen peroxide of 12g/L, sodium hydroxide of 4g/L, CBI of 4g/L, JFC of 1g/L, treatment time of 60min and temperature of 75℃.     

Passivation Mechanism of 316L Stainless Steel in Oxidizing Acid Solution

The compositions and the chemical valence states of elements of 316L stainless steel passive film formed in the oxidizing acid solution were studied by X-ray Photoelectron Spectroscopic (XPS) analysis. The electrochemical polarization curve was measured. The passivation process in the oxidizing acid solution was studied by AC impedance technology. The results indicated that the stable compounds layer was formed on the surface of the sample and the adsorption was the main step in the nitrite solution during passivation process. The catalysis passivation mechanism was put forward according to the experimental results. During passivation process, the water molecule was adsorbed on the surface of the sample at first in the oxidizing acid solution. The oxidizer in the solution played a role as catalyst. The oxide and hydroxide, which could be changed each other and finally formed stable passive film, were generated from adsorbing intermediate under the catalytic action. The mathematical models for predicting the steady polarization curve and the AC impedance spectra at certain conditions have been obtained. The passivation mechanism of 316L stainless steel in the oxidizing acid solution can be interpreted by the catalysis passivation mechanism.     

APPLICATION OF BORON MODIFIED SILICA SOL ON RETENTION AND DRAINAGE

INTRODUCTIONRecently with the high speed, large-scale develop-ment of papermaking, in the manufacture of paper and paperboard conventional single and dual reten-tion and drainage systems cannot obtain satisfying re-tention and drainage. So in 1980 microparticulate systems appeared. Because of its superiority such as good retention effectiveness on fine and chemicals, improving drainage and paper formation, reducing waste water and enhancing the concentration of white water for good recover…     

STUDY ON A NEW NONIONIC MICRIOPARTICLE RETENTION SYSTEM

Microparticle retention system, developed lately, mainly consists of cationic polymers and anionic inorganic substances, such as Hydrocol system consisting of cationic polyacrylamide/modified bentonite and Compozil system[2] with cationic starch/anionic silica sol. The principle of electrostatic interaction has been adopted for these systems. Whereas if there are plentiful anionic trashes in systems, their efficiency will not embody primely. Although anionic trash catcher (ATC) could be adde…     

载体对草酸二甲酯加氢铜基催化剂的影响

以草酸二甲酯加氢反应为基础,研究了二氧化硅载体对铜基催化剂加氢反应性能的影响。催化剂分别以气相硅溶胶、硅胶、二氧化硅为载体,采用沉淀沉积法制备了Cu/SiO2催化剂(wCu=0.20),分别记为CS1、CS2、CS3,催化剂的活性从CS3、CS2到CS1依次增加。XRD测试物相结构表明:氧化态CS2和CS3中存在CuO晶相,而氧化态CS1中活性组分呈无定形分布。还原态催化剂的XRD测试表明催化剂中有Cu2O和Cu0存在,且Cu2O/Cu0的比例按CS3、CS2、CS1顺序增加,XPS分析证实了3个催化剂表面Cu2O/Cu0的比例有相应的变化趋势。这说明Cu2O和Cu0与草酸二甲酯加氢反应活性相关,提高Cu2O的含量,可以提高催化剂的活性。     

聚乙烯胺在CaCO3加填造纸中的作用效果

探讨了在弱碱性条件下聚乙烯胺(PVAm)对CaCO3加填的芦苇浆和废纸浆的助留助滤效果．实验结果表明：PVAm在两种浆中都有非常显著的助滤．助留效果，且在芦苇浆中的助滤效果大于废纸浆．PVAm在芦苇浆中对纤维的助留效果不如废纸浆，但对CaCO3的助留效果高于废纸浆．     

THE APPLICATION OF CATIONIC POLYACRYLAMIDE AS DRAINAGE AND RETENTION AIDS

INTRODUCTIONIn recent years, with the rapid development of paper-making technology[1], such as improvement of pa-per-machine speed, extensive use of high yield and recycling pulp, and more closed white water systems, the environment of papermaking has changed greatly and this has brought many problems, Such as water temperature increasing and water quality becoming worse, large amount of fines in pulp, and more and more aninonic trash in pulp and water. These causes drainability of pulp a…     

APPLICATION OF CATIONIC POLYMERIC MICROPARTICLES ON RETENTION AND DRAINAGE

1.INTRODUCTIONThe microparticles retention and drainage technologywas brought in 1980s. It brings striking effect whenused in wet-end in paper-making. The retention offines and fillings and the drainage of pulp improved alot, meanwhile, the evenness also improved. So, mi-croparticles retention and drainage system is the maindeveloping direction of retention and drainage aids on paper-making industry.All microparticles in microparticle system we use currently are inorganic anionic. It rea…     

阳离子硅镁石助留助滤体系研究

本文研究了阳离子硅镁石作为造纸助留助滤剂的作用及影响因素。结果表明:单独使用时阳离子硅镁石微粒对CaCO3填料及细小组分具有一定的助留助滤作用,但对剪切作用敏感;而当与APMP组成阳离子硅镁石微粒/APMP复合体系时,则表现出良好的助留助滤作用,并且,对pH值的变化及剪切作用均不敏感。在本实验中,硅镁石微粒的最佳加入量为15%(相对于碳酸钙),APAM的最佳加入量为0.5%(相对于碳酸钙)。     

溶胶-凝胶法制备二氧化硅陶瓷纤维的研究

以正硅酸乙酯(Si(OC2H5)4,TEOS)为原料,盐酸为催化剂制备二氧化硅(SiO2)溶胶,与二醋酸纤维素(SCA)成纤助剂均匀混合制备纺丝液,干法纺丝制备连续SiO2凝胶纤维,最后在空气中热解得到SiO2纤维.SCA显著提高了纺丝液的稳定性,在室温下保存24 h以上也不发生显著变化,克服了普通溶胶在可纺丝黏度范围内稳定性差、可纺丝时间短的缺点.研究了不同H2O/TEOS比例对可纺性的影响.结果表明,当摩尔比为3/1时,纺丝液具有优良的纺丝性,同时实现溶胶稳定性和陶瓷产率的合理优化.通过X射线衍射、扫描电子显微镜、力学性能测量对纤维进行了表征.     

聚氧化乙烯助留和助滤性能的探讨

<正>聚氧化乙烯(Polyethlene oxide——简称PEO)是由环醚型的环氧乙烯在催化剂的作用下开环聚合而成的高分子物质,其通式是CH_2·CH_2O。它在水中的溶解性能随其分子量的大小而不同,一般来说,分子量越大,在水中的溶解性能越差。 聚氧化乙烯在造纸工业中的应用,国内已有一些工厂做了试验,取得了一定的成效,他们都是以分散纤维、防止纤维絮聚、提高成纸的均匀性为目的,故称之为分散剂。但普遍反映聚氧化乙烯的价格高,影响造纸厂产品的成本和利润,因此在一定程度上限制了它的使用范围。根据有关资料和我们的分析,认为聚氧化乙烯还是二种极好的助留剂和助滤剂。根据C·H·Tay等人的资料,聚氧化乙烯对纸料中细小粒子的留着作用,较聚丙烯酰胺(PAA)更大(图1)。如果我们能从实验中证实上述作用,那末对缓和聚氧化乙烯在应用中的成本和效果的矛盾,会起到一定的作用。 一、试验材料及方法     

敏捷制造系统及其结构探析

从系统工程的角度剖析了敏捷制造系统的内涵，给出了较完整的概念和主要特征，指出敏捷制造系统和传统制造系统的差异．在制造系统五视图的基础上，构建敏捷制造系统的体系结构。并进行了深入描述．