Effect of various steps of purification on ash content and ash constitution of cellulose. II. Cellulose prepared from sugar-cane bagasse

The effect of the various steps of purification on the ash content and ash constitution of cellulose prepared from bagasse has been examined. After each step of purification, samples were analysed for total ash, SiO₂, Ca, Fe and Mn. Two schemes of purification have been investigated. The first involves acid prehydrolysis, alkaline pulping and bleaching, and the second water prehydrolysis, acid pulping and bleaching. The first scheme has a better effect in diminishing the ash content, and gives a pulp containing 95.8% alpha cellulose with a 90% degree of whiteness.     

Dissolving pulps from Egyptian bagasse I. Effect of depithing on the chemical,physical and sub-microscopic characteristics of viscose pulps

Egyptian bagasse was pulped by the prehydrolysis-sulphate process. The effects of depithing on certain chemical, physical and sub-microscopic characteristics of the pulp, in particular its reactivity towards xanthation, were investigated. Depithing before and after prehydrolysis was compared. Pulps with a higher degree of chemical purity and higher degree of whiteness showed better reactivity towards xanthation. However, the most important factor affecting the reactivity was the accessibility of the cellulose hydroxyls to reactant molecules.     

氯化钠与三乙醇胺复合对粉煤灰水泥水化程度影响的研究

探讨氯化钠与三乙醇胺复合对粉煤灰水泥不同水化阶段水化程度的影响。结果表明:将一定掺量的氯化钠与三乙醇胺复合掺入可以不同程度地提高粉煤灰水泥不同龄期的水化程度,其水化3d的水化程度的增幅最大,水化28d的水化程度的增幅最小;且随着粉磨时间的延长,粉煤灰水泥不同龄期的水化程度均有不同程度的提高但增幅下降。将一定掺量的氯化钠与三乙醇胺复合掺入后粉煤灰水泥不同龄期的水化程度均高于单掺氯化钠或三乙醇胺,其中氯化钠对早期水化程度的提高效果优于三乙醇胺;而三乙醇胺对后期水化程度的提高效果优于氯化钠;当氯化钠掺量为2%,三乙醇胺掺量为0.06%进行复掺且粉磨时间为15min时粉煤灰水泥不同龄期的水化程度均达到最大值。     

马尾松预水解硫酸盐法制人造纤维浆粕工艺的研究

对马尾松制人造纤维浆粕过程中的预水解工艺进行研究,比较了不同液比、最高温度及保温时间的处理效果。研究结果表明:预水解最佳工艺条件为液比1:6;最高温度170℃;保温时间90min。蒸煮工艺采用常规硫酸盐法蒸煮,漂白采用全无氯(TCF)漂白。在此条件下,可获得性能优良的浆粕。     

Saccharification of douglas-fir wood by a combination of prehydrolysis and pyrolysis

A process has been investigated for the saccharification of wood, involving prehydrolysis, lignocellulose pyrolysis, and tar hydrolysis. In this process, ground wood was first prehydrolyzed to remove the more readily hydrolyzable hemicelluloses. The residual lignocellulose was then pyrolyzed rapidly to provide a tar containing levoglucosan and its condensation products. The tar was hydrolyzed to convert these products to glucose. Laboratory experiments have shown that this process can convert a common softwood such as Douglas-fir to 14% char and 42% hexoses. This amounts to a 59% recovery of the hexoses: 32% from prehydrolysis and 27% from pyrolysis. The prehydrolysis served not only to remove hemicelluloses, but also to increase the yield of glucose from pyrolysis and subsequent tar hydrolysis. It has been shown that this enhancement is due to the removal of inorganic ash and the catalytic effect of trace amounts of acid remaining in the lignocellulose.     

Preparation and properties of chemical cellulose from ascidian tunic and their regenerated cellulose fibers

Chemical cellulose (dissolving pulp) was prepared from ascidian tunic by modified paper‐pulp process (prehydrolysis with acidic aqueous solution of H₂SO₄, digestion with alkali aqueous solution of NaOH/Na₂S, bleaching with aqueous NaOCl solution, and washing with acetone/water). The α‐ cellulose content and the degree of polymerization (DPw) of the chemical cellulose was about 98 wt % and 918, respectively. The Japanese Industrial Standard (JIS) whiteness of the chemical cellulose was about 98%. From the X‐ray diffraction patterns and ¹³C‐NMR spectrum, it was found that the chemical cellulose obtained here has cellulose Iβ crystal structure. A new regenerated cellulose fiber was prepared from the chemical cellulose by dry–wet spinning using N‐methylmorpholine‐ N‐oxide (NMMO)/water (87/13 wt %) as solvent. The new regenerated cellulose fiber prepared in this study has a higher ratio of wet‐to‐dry strength (<0.97) than commercially regenerated cellulose fibers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1634–1643, 2002.     

Incorporation of the ash from cellulignin into vitrified ceramic tiles

The incorporation of the ash from cellulignin, a catalytic biofuel, into a clay/feldspar body was investigated. The cellulignin was obtained by acidic prehydrolysis and was then burnt in boilers leaving behind the ash as a solid residue. Characterization tests of the ash employed X-ray diffraction, particle size distribution, mercury porosimetry, chemical analysis, thermal analysis and high-resolution scanning electron microscopy. The ash/clay/feldspar compositions were fired at 1200 °C and the linear shrinkage, water absorption and flexural strength were determined. Solution and leaching tests were conducted to evaluate the environmental safety of the final ceramics. The results showed that the ash is mainly composed of quartz with partially nanometric particle size, high surface area and high content of alkaline and alkaline earth oxides. These are advantages for a potential use of this ash as a flux. The partial replacement of feldspar by ash promoted a better vitrification decreasing the open porosity and increasing the mechanical strength. Heavy metals present in the ash became inert after the firing stage.     

Structure-related behavior of hybrid organic–inorganic materials prepared in different synthesis conditions from Zr-based NBBs and 3-methacryloxypropyl trimethoxysilane

The copolymerization of zirconium oxo-clusters (Zr12) with 3-methacryloxypropyl (trimethoxy)silane (MPTMS), using a Si/Zr molar ratio of 4, was investigated. The hybrid samples were prepared both with and without organosilane prehydrolysis. Differential scanning calorimetry (DSC), multinuclear liquid, and solid state NMR analyses and Fourier transform infrared (FTIR) spectroscopy were used to characterize the hybrid materials and study the influence of synthesis conditions on condensation and polymerization. The degree of condensation (DOC) of the silsesquioxane network and the polymerization yield are generally high. However, the organosilane prehydrolysis step leads to the reduction of the extent of phase interaction, thus favoring the phase separation between silica-zirconia-based domains. Dynamic mechanical spectroscopy (DMS) analyses were performed on the hybrid polymers obtained by means of the two synthetic pathways. The sample prepared without the organosilane prehydrolysis step presents a higher glass transition temperature (T_g) than the one with silane prehydrolysis. By heating above the T_g, the samples retain shape and size, due to the lack of viscous flow. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Alkali-assisted coal extraction with polar aprotic solvents

Coal extraction experiments were conducted using a coal, containing ca. 10% ash, from the Tshikondeni mine in South Africa. This coal dissolves only to a limited extent in pure polar aprotic solvents such as dimethylformamide (DMF) and N-methyl-2-pyrrolidinone (NMP). However, the addition of a strong base, e.g. sodium hydroxide (NaOH) or sodium tert-butoxide increased the degree of coal dissolution in these organic solvents. Depending on the extraction conditions, carbon extraction efficiencies of up to 90% were obtained. Carbon precursor material was recovered from the solution as a gel by precipitation with water. Ash content was reduced from 10% in the coal to less than 1.6% in the coal extracts. Sodium sulfide (Na₂S) addition further reduced ash content and aided the recovery of carbon precursors that led to graphitizable cokes but the degree of extraction was significantly reduced.     

水热预水解分离相思木半纤维素及其组分与结构分析

通过水热预水解法处理相思木制得预水解液,采用乙醇沉淀回收预水解液中的半纤维素,通过条件实验优化了最佳回收半纤维素的预水解条件,然后对回收的半纤维素进行热稳定性、成分和结构分析。结果发现,获得最大半纤维素回收率的预水解条件为170℃/20min,原料中碳水化合物回收率为3.93%,回收的半纤维素中木糖为主要成分占75.56%,葡萄糖占10.71%,半乳糖占7.80%。离子色谱分析表明160℃/40min,170℃/15min、170℃/25min和180℃/15min水解条件下的回收半纤维素组分与170℃/20min时的回收半纤维素化学组分相同,但含量上略有差别;热重分析表明水解温度提高和时间延长使回收半纤维素热稳定性降低;核磁共振和红外光谱分析结果表明回收半纤维素的聚木糖主链上残留有乙酰基、阿拉伯糖和半乳糖连接。     

粉煤灰对碾压混凝土耐久性的影响

用于大体积混凝土工程的碾压混凝土，其耐久性好坏直接关系到重大工程的使用及寿命。从抗渗性、抗冻性、抗冲磨性、抗碳化性及抗化学侵蚀性等方面研究了粉煤灰对碾压混凝土耐久性的影响。结果表明：（1）粉煤灰能提高碾压混凝土后期的抗渗性；（2）在碾压混凝土中增加粉煤灰的用量，提高胶凝材料的总量，从而降低混凝土的水灰比，能提高碾压混凝土抗冻性：（3）粉煤灰掺量不大于15％时，粉煤灰掺量对碾压混凝土的抗冲磨性能影响甚微；（4）粉煤灰掺量不大于50％时，经碳化后混凝土的抗压强度反而有所提高；（5）碾压混凝土的水化产物长期稳定性较好，且因有粉煤灰的二次水化消耗了部分Ca（OH）2，故其抗镁盐及硫酸盐侵蚀的能力较强。     

高掺量粉煤灰混凝土强度发展潜力

测定了粉煤灰火山灰的反应率;估算了粉煤灰火山灰反应所需的最小水泥用量[或Ca(OH)2量];研究了高掺量粉煤灰混凝土的长期强度增长趋势。试验结果表明:粉煤灰的火山灰反应程度极其有限,极限火山灰反应率不大于20%;高掺量粉煤灰混凝土不会存在所谓“贫钙”问题;与普通混凝土相比,高掺量粉煤灰混凝土具有更强的后期强度增长趋势。     

Soy oil lutein adsorption by rice hull ash

Rice hull material was converted to an adsorbent of the soy oil pigment, lutein, by a combination of ashing and acid activation. Pigment was adsorbed from a 20% (v/v) soy oil/hexane miscella. The most effective ashing temperature was 500°C. Five percent acid activation significantly promoted adsorption of the ash, but greater acid activation did not increase adsorption capacity very much. In the system studied, the performance of activated ash was comparable to that of activated bleaching earth. Nonactivated ash also had an ability to bind lutein but was less effective than activated adsorbent. The absorbance spectrum of the residual lutein was not altered by rice hull ash, but was changed when exposed to bleaching clay.     

杨木预水解液中化学组分质量浓度的P因子调控

为研究P因子对木质纤维原料预水解液中化学组分质量浓度的调控机制,分析了不同预水解温度（170~210℃）和预水解时间（30~120 min）条件下,杨木预水解液中固形物、木质素、木糖和葡萄糖质量浓度的变化规律。结果表明：升高预水解温度和延长预水解时间,固形物、木质素和葡萄糖质量浓度均逐渐增大。而木糖质量浓度随温度的升高而降低;190℃时,木糖质量浓度随预水解时间延长迅速减小。P因子对杨木预水解液中化学组分的质量浓度具有调控作用。固形物、木质素和葡萄糖质量浓度随P因子增加呈指数增大。而木糖质量浓度随P因子增加呈指数减小,P因子小于3 300时,木糖质量浓度随P因子增加迅速减小。     

Fabrication and properties of peroxide cellulose from coniferous and deciduous wood for chemical processing

Acid prehydrolysis does not impede subsequent peroxide delignification, increases the mass fraction of α-cellulose, and improves the reactivity of cellulose but does not ensure a high degree of modification. Aqueous prehydrolysis is less effective. Cold alkaline modification of coniferous (spruce) prehydrolysis peroxide cellulose is highly effective and increases the mass fraction of α-cellulose to 97.5%. Deciduous wood is delignified and modified more easily than coniferous wood. Deciduous (birch) cellulose with up to 99% mass fraction of α-cellulose can be obtained by peroxide cooking with acid prehydrolysis, finishing, and cold alkaline modification. The process regimes developed allow processing highly modified coniferous and deciduous cellulose with properties as good as sulfate cord cellulose with minimal technogenic environmental pollution. Based on proceedings of the memorial conference dedicated to the 100th birthday of Z. A. Rogovin. __________ Translated from Khimicheskie Volokna, No. 1, pp. 25–29, January–February, 2006.     

Effect of various steps of purification on ash content and ash constitution of cellulose. I. Cellulose prepared from cotton linters

The effect of the various steps of purification on the ash content and ash constitution of cellulose prepared from cotton linters has been examined. After each step of purification, samples were analysed for total ash, SiO₂, Ca, Mg, Fe, Al, Cu and Mn. Two methods of bleaching were investigated. The first involves double treatment of cellulose with sodium hypochlorite solution, and the second one treatment with hypochlorite followed by another treatment with sodium chlorite solution. The second method has a better effect in diminishing the ash content.     

Studies on the pulping of egyptian cotton linters by the nitric acid process

Egyptian cotton linters were pulped by the nitric acid process. In order to reduce the high ash and silica contents of the resulting pulps it was found necessary to apply hot refining with sodium hydroxide solution. Different conditions of concentration, temperature, and pressure in the refining step were investigated. Refining before and during bleaching were compared.     

Adsorption of carotene from palm oil by acid-treated rice hull ash

Rice hull ash obtained by heat treatment and acid activated followed by washing was not effective as an adsorbent for carotene in palm oil in contrast to that reported for adsorption of soy oil lutein. However, unwashed acid-activated ash had activity much higher than carbon and silica but slightly less than a commercial bleaching clay. Heat treatment of raw rice hulls at temperatures below 300°C resulted in the most active adsorbent after acid activation. Drying the unwashed acid-activated ash at temperatures higher than 200°C reduced the activity. The activity of the acid ash was attributed to adsorbed acid. The results also suggested that the removal of carotene in palm oil was caused by chemical interactions involving the adsorbed acid and the carotene. The small amount of Fe³⁺ in the ash was not responsible for the activity.     

含C_4A_3矿物硅酸盐水泥中混合材反应程度的研究

采用非蒸发水量法测定含硫铝酸钙矿物水泥的水化程度 ,萃取法测定该水泥中混合材的反应程度 ,通过SEM/EDS观察分析水化产物形貌和种类。结果表明 :粉煤灰水泥的水化程度高于同龄期的矿渣水泥的水化程度 ,粉煤灰的反应程度高于矿渣的反应程度。同龄期粉煤灰水泥中的水化产物多于矿渣水泥的水化产物 ,且水化产物发育更良好     

Factors determining the steradiene formation in bleaching and deodorisation

Steradienes are steroidal hydrocarbons formed by a sterol dehydration reaction during the vegetable oil refining process. The influence of the bleaching and deodorisation process conditions on the formation of steradienes was studied by use of mathematical model equations. During the bleaching process steradienes are formed due to a dehydration catalysed by the acid‐activated bleaching earth. By increasing the bleaching temperature from 90 to 110 °C a gradual increase in the steradiene concentration from 5.1 to 22.3 ppm was observed. The steradiene content linearly increased with increasing bleaching earth concentration and increasing degree of acid activation. Steradiene formation was also observed at elevated temperatures applied during the deodorisation. Steradienes were distilled during deodorisation and recovered in the deodoriser distillate. Depending on the deodorisation temperature 0.046—1.06% of the free sterols were dehydrated, resulting in the formation of steradienes.