Physical Characterization of Pulps. I. Rice Straw Bleached by Nonconventional Multistage Method and Paper Sheet Making

Rice straw pulp has been bleached by a nonconventional fourstage method using organic solvents in the bleaching solutions. Methanol, ethanol, acetone, and dioxane, 10%, 30%, and 50% by volume were mixed with water as bleaching media in the first-stage process. Effects of kind and percentage of the organic solvent in the bleaching mixtures on the physical characterization of the bleached pulps and of the paper sheets were studied. Results are discussed on the basis of changing the physicochemical properties of the media by varying the solvent content in the bleaching mixture.     

Physicochemical Properties of Prepared Cellulose Sulfates: II. From Linen Pulp Bleached by the H2O2 Method

Abstract

Some cellulose sulfates were prepared from linen pulp bleached by the H₂O₂ method. The infrared spectroscopy (IR) and the dielectric properties of the samples prepared under different conditions were studied. The results show that the mean hydrogen bond strength (MHBS) values increased by sulfonation while the asymmetric index decreased. The dielectric and the IR measurements gave more light on the structure and composition of the investigated samples.     

Physical Characterization of Pulps. II. Rice Straw and Bagasse Pulps Bleached by Nonconventional Two-Stage Hydrogen Peroxide Method and Paper Sheet Making

The conventional two-stage H₂O₂ method was applied for bleaching rice straw and bagasse pulps. The pulps were bleached also by a nonconventional method: i.e., using different organic solvents with various contents in the first stage of the bleaching process. The effects of the kind and percentage of the organic solvent in the bleaching mixture on the properties of both the bleached pulps and paper sheets were studied and are discussed on the basis of the physicochemical properties of the bleaching mixtures.     

吐温80对麦草浆过氧化氢漂白的促进作用

研究了表面活性剂吐温80(Tween 80,聚氧乙烯山梨醇酐单油酸酯)在麦草浆过氧化氢漂白中的助漂作用。对OQP/T、OQPT和OQTP三种OQP与表面活性剂Tween 80配合漂白工艺的对比结果表明,OQP漂白后再采用表面活性剂Tween 80辅助漂白可获得较好的漂白效果。当表面活性剂用量为0.8%时,其漂白浆白度可达75.2%,黏度为794 mL/g,表明Tween 80有明显的辅助漂白作用。在此条件下,漂白浆的耐破强度、撕裂强度较对照OQP漂白浆有显著提高,而抗张强度基本不变,仅耐折强度有所下降。     

Bleaching of Rice Straw Paper Pulp and Possibilities for Replacement of Sodium Hydroxide by Ammonium Hydroxide During the Extraction Stage

Bleaching of rice straw soda pulp was investigated under various conditions. The rate of the chlorination and hypochlorite reactions were studied; the best properties were attained by shortening the chlorination time to about 20 min. The extraction efficiency of ammonium hydroxide on chlorinated soda pulp was also investigated. The effectiveness of extraction can be deduced from the reduction of the kappa number, cuprammonium viscosity and the brightness obtained after the hypochlorite step. Extraction can be carried out with ammonium hydroxide instead of sodium hydroxide used in the conventional method. The strengths of unbleached and fully bleached pulps were evaluated. The fully bleached ammonium hydroxide extracted pulps were beaten faster and were usually stronger than the corresponding pulps extracted with sodium hydroxide.     

Supported Pd and PdAu Nanoparticles on Ti-MCM-41 Prepared by a Photo-assisted Deposition Method as Efficient Catalysts for Direct Synthesis of H2O2 from H2 and O2

An efficient methodology to synthesize highly active Pd nanoparticles using a single-site photocatalyst under UV-light irradiation has been developed for the synthesis of hydrogen peroxide (H₂O₂) from H₂ and O₂. By the photo-assisted deposition (PAD) method, Pd precursor can be deposited directly on the photo-excited tetrahedrally coordinated metal-oxide moiety within the silica frameworks, and subsequently transformed into Pd nanoparticles by H₂ reduction. The mean diameter of the deposited Pd particles determined by CO adsorption and the catalytic activities in the direct synthesis of H₂O₂ were strongly dependent on the preparation method and kind and/or amount of metal-oxide moieties. Here, the use of Ti-containing mesoporous silica (Ti/Si = 0.01) acted as a most efficient support for the above reaction. The PAD method also provides PdAu bimetallic nanoparticles from an aqueous solution of mixture of PdCl₂ and HAuCl₄. The PdAu/Ti-MCM-41 catalyst prepared by the PAD method was shown to perform significantly better activity than the pure Pd/Ti-MCM-41.     

响应面法优化秸秆多孔材料的制备工艺条件

以秸秆为原料,微波干燥后经炭化、活化处理制备出一种新型多孔材料。以响应面法对多孔材料的制备工艺进行优化,并用扫描电镜、N_2-物理吸附(BET)分析和X射线衍射(XRD)等分析手段对产物的结构和性质进行了表征。结果表明,该多孔材料的最佳制备条件为活化反应温度707.40℃、炭化样品与KOH质量比1:3、活化反应时间17.20 min,在此条件下制备的材料具有较好的多孔性和较大比表面积,孔径集中在5.6~13 nm,比表面积达1 463.15 m~2/g,是孔径较大的介孔材料。     

Adsorption Behavior of Iminodiacetic Acid Type of Chelating Gel Prepared from Waste Paper

Abstract

Adsorption gel was prepared from waste recycled paper by immobilizing iminodiacetic acid (IDA) functional group by chemical modification. The gel exhibited good adsorption behavior for a number of metal ions viz. Cu(II), Pb(II), Fe(III), Ni(II), Cd(II), and Co(II) at acidic pH. The order of selectivity was found to be as follows: Cu(II)>Pb(II)>Fe(III)>Ni(II)～Cd(II)～Co(II). From the adsorption isotherms, the maximum adsorption capacity of the gel for both Cu(II) and Pb(II) was found to be 0.47 mol/kg whereas that for Cd(II) was 0.24 mol/kg. A continuous flow experiment for Cd(II) showed that the gel can be useful for pre‐concentration and complete removal of Cd(II) from aqueous solution.     

H2O2氧化降解壳聚糖研究

介绍了国内外壳聚糖降解制备低聚壳聚糖的主要方法，并对H2O2氧化降解制备低聚糖进行了正交实验，探讨了该降解过程中各影响因素对降解产物的影响。     

微波-凝胶法合成纳米Y2O3稳定ZrO2微粒的研究

研究以聚丙烯酰胺为分散剂,采用微波-凝胶法制备纳米Y2O3稳定ZrO2(YSZ)微粒的条件.分别用红外光谱(IR)、X射线粉末衍射(XRD)、扫描电镜(SEM)及电测量技术,对纳米YSZ微粒的结构与性能进行了表征.结果表明:在650℃微波热处理得到立方相纳米YSZ微粒,平均粒径为35nm左右,在450～1000℃温度范围内呈现出较高的电导率,材料稳定性较好.     

均匀凝胶法制备CuO-ZnO-Al2O3-Cr2O3/HZSM-5催化二氧化碳加氢合成二甲醚

采用均匀凝胶法制备了CuO-ZnO-Al2O3-Cr2O3/HzSM-5催化剂,采用X射线衍射(XRD)、傅立叶红外光谱(FT-IR)和热重-差热分析(TG-DTA)进行了表征,并在固定床微型反应器中考察了反应温度、反应压力,CuO与ZnO质量比、Al2O3和Cr2O3的质量分数对CuO-ZnO-Al23-Cr2O3/HzSM-5催化剂在CO2加氢制备二甲醚反应中催化性能的影响.结果表明,在533 K,3MPa,H2与CO2体积比为3和反应混合气体积空速为1600 h-1的条件下,在CuO与ZnO质量比2,Al2O3和Cr2O3分别占催化剂质量的10.0%和1.5%的CuO-ZnO-Al2O3-Cr2 O3/HZSM-5催化剂作用下,CO2的单程转化率达到28.94%,二甲醚的选择性和收率分别为31.76%和8.76%,甲醇和二甲醚的总收率达到13.98%.     

溶胶-凝胶制备Li2O-Al2O3-SiO2微晶玻璃的研究进展

Li2OAl2O3SiO2系统微晶玻璃由于其膨胀系数低,耐高温及抗热冲击性等优异性能而受到广泛重视。本文主要介绍了溶胶凝胶工艺原理、制备过程,及在Li2OAl2O3SiO2系微晶玻璃上的应用,最后简述了Li2OAl2O3SiO2系微晶玻璃的应用现状。     

乙二醇辅助水热法制备纳米氧化铁的研究

采用乙二醇辅助水热法制备纳米结构的氧化铁,产物通过XRD进行了表征;同时考察了反应时间纳米氧化铁产率的影响。结果表明:制备的最适条件为pH值为11,反应温度90℃,控制反应时间为15 h。     

固态反应法制备CaCu3-xMgxTi4O12陶瓷的介电性能研究

利用固态反应法制备了CaCu3-xMgxTi4O12（x=0,0．2,0．4,0．6,0．8,1．0）陶瓷,并分析探讨了MgO添加量对其介电性能的影响。研究结果表明,添加MgO后陶瓷晶粒有变小的现象,且MgO的添加摩尔比为0．6时其介电常数最佳,但介电常数随频率增加下降也较快;MgO添的加摩尔比为0．2和0．4时虽然介电常数增加较少,但随频率变化幅度却较小。在频率〈1000Hz时添加MgO会使陶瓷使的介电损耗大幅上升,这表明添加MgO有降低电阻的效果。     

氢氧直接合成法制过氧化氢技术进展

氢气和氧气直接合成过氧化氢是典型的原子经济性反应，因过程简单、产品清洁、生产成本低而成为催化领域研究开发的一个热点。总结了该法近年来在催化剂活性组分的选取及载体方面的进展；详细介绍了溶剂的选取和反应机理；讨论了各种反应器的安全性。指出今后的研究重点是提高氢气利用率、开发新型的反应器、提高过程的安全性。     

草浆造纸废水处理的工艺研究

应用浸没燃烧浮选木质素、絮凝除硅、软填料和灰渣过滤工艺过程对草浆造纸废水进行处理研究,确定了最佳工艺条件为：浮选木质素的ｐＨ值为３、絮凝沉降的ｐＨ值为９～１０。各项指标均达到国家规定的排放标准。估算吨水成本为０．６５元,技术经济可行。     

固相合成微波介电陶瓷Ba2La2Ti2NbO12及介电特性研究

通过固相反应法合成了类钙钛矿结构新铌酸盐Ba2La2Ti2NbO12。分别采用X射线衍射分析、扫描电镜进行了结构分析,并进行了介电性能测试。结果表明：Ba2La2Ti2NbO12室温时为六方层状类钙钛矿结构,有优异的介电性能。晶胞常数为：a=b=5．6726（3）A,c=27．740（2）A,V=773．04（9）A3,Z=3,陶瓷体具有高的介电常数42．7,较高的品质因子31,130GHz,介电常数温度系数-4．2ppm°C-1。     

固态反应法制备CaCu3-xMgxTi4O12陶瓷的介电性能研究

利用固态反应法制备了CaCu3-xMgxTi4O12(x=0,0.2,0.4,0.6,0.8,1.0)陶瓷,并分析探讨了MgO添加量对其介电性能的影响.研究结果表明,添加MgO后陶瓷晶粒有变小的现象,且MgO的添加摩尔比为0.6时其介电常数最佳,但介电常数随频率增加下降也较快;MgO添的加摩尔比为0.2和0.4时虽然介电常数增加较少,但随频率变化幅度却较小.在频率＜1 000 Hz时添加MgO会使陶瓷使的介电损耗大幅上升,这表明添加MgO有降低电阻的效果.     

K2Ti6O13薄膜电极的制备及其光电化学

采用溶胶-凝胶法制备了隧道状结构的K2Ti6O13薄膜电极. 溶胶-凝胶法解决了K2Ti6O13与导电基材间结合差的难题,实现了该电极良好的导电性能. 在此基础上,通过紫外-可见光吸收光谱结合电化学方法确定了K2Ti6O13薄膜的能带结构. 溶胶-凝胶法制备的TiO2薄膜电极用于验证方法的可靠性,并作为K2Ti6O13薄膜结构和性能特征的参照系. 实验结果表明,制备的K2Ti6O13薄膜电极禁带宽度为3.05 eV,小于K2Ti6O13粉体的禁带宽度(3.45 eV)和TiO2薄膜的禁带宽度(3.22 eV),具有可见光响应能力. 同时,K2Ti6O13薄膜电极的导带电位(-0.77 V, vs. NHE)低于TiO2薄膜电极(-0.61 V, vs. NHE),显示其还原能力优于TiO2薄膜电极,具有较强的光解水产氢潜力. 此外,K2Ti6O13薄膜的电化学表征还表明其具有很好的电子-空穴分离能力和材料稳定性. 因此,制备的K2Ti6O13薄膜在可见光光解水制氢领域将有较好的应用潜力.