化学纸浆的氧脱木质素

系统阐述了氧脱水质素的作用机理、反应动力学及影响因素,详细介绍了氧脱木质素的各种预处理方法及特点,总结并评价了氧脱木质素的工艺特性。     

纤维素的溶解及活化过程

纤维素衍生物的制备过程主要包括纤维素纤维的活化和化学反应两个环节,其中活化过程是十分关键的一步,活化过程的优劣直接决定着纤维素纤维衍生化反应的均匀性、效率以及所得纤维素衍生产物的理化性能。文章对纤维素衍生化反应中的活化过程的进展进行了详细的说明,并从技术、经济和环保的角度对今后纤维素活化方法的进一步发展进行了分析和估计。     

Colour gamut produced by applying mixtures of natural dyes on de-inked mechanical pulp

Plants that are available from various regions of Greece were investigated as sources of natural dyes in a paper-dyeing operation. The production of natural dyes was achieved by aquatic extraction of plant materials in order to obtain an environmentally friendly method of producing the dyes. The extracted dyes were applied on de-inked mechanical pulp. A broad variation in shade and colour depth was achieved by applying mixtures of plant extracts in various combinations. The produced colours were found to lie in the first and second quadrant of a two-dimensional chromatic diagram.     

Cellulose triacetate prepared from low-grade hardwood dissolving pulp and its insoluble residues in acetylation mediums

As cellulose triacetate is prepared from low-grade hardwood dissolving pulp, a considerable amount of the insoluble residue was present in the acetylation medium of the acetic acid/acetic anhydride/sulfuric acid system. The characterization of this residue indicated that the insoluble residue is composed of cellulose triacetate and xylan diacetate, retaining a fiber structure of swollen form. To reduce the insoluble residues, reaction conditions for acetylation were investigated. As one of the remedies of reducing the insoluble residues, 17 different solvents were selected to add to the acetylation medium, and among these, dichloroacetic acid was found to be very effective for its reduction. The obtained cellulose triacetate could then reveal good thermal properties similar to that from high-grade dissolving pulps. Therefore, acetylation systems with an addition of an appropriate solvent can have a potential to industrially manufacture a high-quality cellulose triacetate from even low-grade hardwood-dissolving pulps, as observed in low-grade softwood-dissolving pulps. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 289–297, 1998     

ICP-AES法快速测定水泥的化学成分

电感耦合等离子体发射光谱仪法（简称ICP-AES法）具有分析速度快、灵敏度高、线性范围宽和检出限低,并且多元素能同时测定等一系列优点。本文采用盐酸（1＋1）溶解水泥样品,利用该仪器同时测定水泥中Mg、Fe、Ca、Si、K、S和A1七种元素的含量,然后换算成相应的氧化物组分的含量。     

Extractive rectification by means of sulfolane in chemical technology: A review

This review covers recent research on extractive rectification by means of sulfolane to isolate and purify organic components.     

Highly accessible or decrystallized cotton by chemical methods

To obtain highly accessible cotton by cyanoethylation with acrylonitrile after pretreatment with swelling agents, the effect of various swelling agents was examined. Swelling agents such as lithium hydroxide, sodium hydroxide, potassium hydroxide, ethylamine, triethylamine, ethylenediamine, piperazine, benzyltrimethylammonium hydroside (BTMOH), urea, dimethyl sulfoxide, dimethylformamide, zinc chloride, and liquid ammonia were examined. It was found that the sodium hydroxide pretreatment or the dual pretreatment with either potassium hydroxide, ethylenediamine, or BTMOH, and sodium hydroxide prior to acrylonitrile treatment gave modified cottons having moisture regain as high as 14%. In such cases, maximum values of moisture regain were observed at the degrees of cyanoethylation of 5–8%.     

化学浆含氯漂白废水的污染控制

本文综述了化学浆含氯漂白废水的污染特性及其控制方法。介绍了对污染控制的内部处理和外部处理方法。     

Tunable TiO2 (anatase and rutile) materials manufactured by mechanical means

Anatase and rutile are two naturally found titanium dioxide phases with attractive dielectric, catalytic, and photo-catalytic characteristics. Anatase and rutile are photo-catalytically active in the UV region, since their band gaps are 3.2 eV and 3.75 eV, respectively. In this work is proposed a cost-effective, easy to launch methodology for modification of the TiO₂ bandgap. Such modifications will make the oxides photo-catalytically active in a wider optical range from the visible wavelengths to an extended UV spectrum. The proposed methodology is based on mechanical means such as mixing and milling. Various ratios of anatase:rutile were investigated and milled from 0 (mixing only) to 50 h using high energy mills. The results on mixing and milling show that it is possible to modify the bandgap of the TiO₂ from 2.53 eV to 4.04 eV. The characterization was conducted by means of X-ray diffraction, Raman spectroscopy, Scanning electron microscopy, and optical spectroscopy.     

Effects of solvent addition to acetylation medium on cellulose triacetate prepared from low-grade hardwood dissolving pulp

As cellulose triacetate was prepared from low-grade hardwood-dissolving pulp, a considerable amount of the insoluble residue was present in the acetylation medium of the acetic acid/acetic anhydride/sulfuric acid system, and it consisted mainly of cellulose triacetate (CTA) and xylan diacetate (XDA). As one of the remedies for reducing the insoluble residue, a solvent was added to the acetylation medium and the effects of the solvent addition on the amount of insoluble residue formed were studied. To do so, 17 different solvents were selected so as to cover a wide range of solubility parameters. The obtained results clearly indicated that the addition of the solvent affects the amount of insoluble residue and that, excluding dichloroacetic acid, nitromethane was effective for its reduction, but that neither methylene chloride nor nitroethane were in spite of their effectiveness for softwood-dissolving pulp, which would be due to the intrinsic properties of XDA on the solubility in the acetylation medium. A new acetylation system with such an appropriate solvent would, therefore, provide a clue as to an industrial usage of the low-grade hardwood-dissolving pulps for cellulose acetate production. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1445–1449, 1998     

Microstructural and mechanical changes by chemical ageing of glazed ceramic surfaces

In the present work, several ceramic tiles, characterised by different glazes, were considered in order to define the role played by the glassy and crystalline phases on the leaching mechanisms and the deterioration of the mechanical properties. The glazed working surfaces were subjected to chemical attack by using a strong basic solution and the chemical analysis of the leached solutions was performed. Before and after the chemical attack, the glazed surfaces of the samples were analysed from both the microstructural and mechanical point of view. In this context, the microstructure was observed by SEM and analysed by X-ray diffraction. In order to define other possible changes, roughness measurements, Vickers hardness and micro-scratch tests were also performed.The results made it possible to deepen the understanding of the mechanisms of elements release caused by the chemical attack and their implications on microstructural and mechanical degradation of the working surface of glazed ceramic tiles.     

Conversion of chemical into mechanical energy by contractile polymers performed by polymer complexation

A mechanochemical energy conversion system working upon polymer-polymer complexation between poly(methacrylic acid) (PMAA) and poly(ethylene glycol) (PEG) was studied. It was found that among PEGs of various molecular weights used, PEG with molecular weight of 2000 provided the most rapid and significant contraction of crosslinked PMAA membrane loaded 100 times the weight of dry membrane, exhibiting about 2000 g/cm² of stress. Increasing and decreasing the molecular weight of PEG from 2000 brought about gradual decrease both in the contraction and stress of the membrane. The work done per contraction per gramme of contractile substance was studied for various loads. It was found that the work done increased linearly with increasing weight of load, reaching 200 g cm.     

化学机械抛光技术研究进展

通过回顾化学机械抛光技术的发展历史,概述了化学机械抛光作用机制与实际应用情况,着重阐述了几种重要抛光浆料(如CeO2、SiO2、Al2O3抛光浆料)的优缺点、抛光机理及其国内外新近制备方法,进一步展望了化学机械抛光技术的发展前景与新型抛光浆料的开发方向.     

Boron removal by means of chemical precipitation with calcium hydroxide and calcium borate formation

Boron removal was investigated by chemical precipitation from aqueous solutions containing boron using calcium hydroxide. pH, initial boron concentration, amount of Ca(OH)₂, stirring speed and solution temperature were selected as operational parameters in a batch system. The highest boron removal efficiency was reached at pH 1.0. Increasing initial boron concentration and amount of calcium hydroxide raised to boron removal efficiency. Boron removal efficiency was highest at a stirring speed of 150 rpm. The most important parameter affecting boron removal efficiency was solution temperature. Increasing solution temperature increased importantly boron removal. XRD analysis showed that CaB₃O₃(OH)₅·4H₂O, which is a borate mineral called inyoite, occurred between Ca(OH)₂ and borate ions. As a result of the obtained experimental data, when the optimum operational conditions were selected, over 96% of boron removal efficiency was reached by this method.     

Sintering highly conductive ZnO:HCl ceramics by means of chemical vapor transport reactions

The features of sintering ZnO ceramics by means of chemical vapor transport (CVT) in sealed quartz chambers were investigated. CO, C, H₂, HCl, HCl + H₂, HCl + C, HCl + Zn and HCl + H₂+ C mixtures were used as transport agents (TAs) at the 925–1070 °C temperature range. The exact thermodynamic analysis of compound CVT systems, carried out for wide temperature and loaded TA pressure ranges, was applied to establish the relation between medium composition and the characteristics of sintered materials. The advantages of some compound TAs based on HCl were shown. ZnO:HCl ceramics with a diameter of 25 mm (99 ± 1% of the initial diameter of the sintering powder), a density of 5.1 ± 0.3 g/cm³, a hardness of 2.0 ± 0.2 GPa, a resistivity of 2.4⋅10^-2 Ω cm, and a controllable stoichiometric deviation, were obtained. The investigated materials have no contamination from metallic Zn, ZnCl₂ or solid C. The doping efficiency of ZnO ceramics by oxides of various metals, by means of low temperature CVT reactions with ZnCl₂ vapors as a TA, was calculated for oxides of all non-radioactive metals of the periodic table.     

Investigations on twenty Australian sewage sludges — their evaluation by means of chemical analysis

To evaluate twenty sludges from different places in Australia for disposal on arable land, these sludges were extracted with (a) HNO₃ to determine the ‘total’ contents of some heavy metals and other elements; (b) a solution containing DTPA to determine contents of ‘available’ heavy metals; and (c) with a CaCl₂-solution to determine contents of water-soluble heavy metals and some other elements. Measurements of the pH of the sludges, their electrolytic conductivity, NaHCO₃-extractable P, water-extractable Cl, and contents of ash and organic carbon were also made. The HNO₃-extractable Cd, Cu, Mn, Ni, Pb, and Zn in the sludges were compared with those in sludges from three other countries. High correlations between HNO₃-extractable and DTPA-extractable metals were found in the Australian sludges; therefore, the HNO₃ is equally good as the DTPA as an extractant of heavy metals in sewage sludges. The correlations between HNO₃- and CaCl₂-extractable Cd, Cu, Mn, and Zn were not significant. ‘Young’ and ‘aged’ sludges from the same treatment plants consistently differed in their Na and Cl contents, which were lower in the ‘aged’ sludges. A wheat experiment treated with high application rates of a saline and metalliferous sludge showed that the balance of nutrients and the amount of soluble salts in a sewage sludge are of greater direct importance to the growth of plants than the heavy metal content of that sludge.