聚氨酯海绵的预处理对网眼多孔陶瓷性能的影响

用聚氨酯海绵法制备网眼多孔陶瓷。研究了聚氨酯海绵的差热-热重曲线及表面处理对网眼多孔陶瓷挂浆性能的影响。结果表明：聚氨酯海绵在700℃左右完全氧化分解。经过酸碱处理,再用羧甲基纤维素溶液、无机溶胶和聚碳硅烷溶液进行表面改性后,聚氨酯海绵的孔筋表面粗糙度增大,同时改善了它与浆料的润湿性能,使浆料在聚氨酯海绵上的挂浆量增加。随着浆料在聚氨酯海绵上挂浆量的增加,网眼多孔陶瓷的体密度增大,制得的网眼多孔陶瓷的抗压强度增加。经无机溶胶表面改性处理的聚氨酯海绵制得的网眼多孔陶瓷的抗压强度为0.79MPa,比用未经处理的海绵制得的多孔陶瓷（0.45MPa）提高大约75％。     

有机泡沫预处理对其挂浆性能的影响

采用有机泡沫浸渍工艺制备泡沫陶瓷。研究了聚氨酯泡沫预处理对泡沫挂浆性能的影响。结果表明,以浓度为10%的碱液对孔径为10PPI的聚氨酯泡沫进行水解处理,在60℃条件下,水解15min左右,并结合对泡沫表面进行的改性处理,可获得增重倍数高达7.8的挂浆性能优异的聚氨酯处理泡沫。     

对包钢稀土矿进行多孔陶瓷材料的制备与研究

为了更好的探究包钢稀土矿的烟气脱硝机理,利用有机泡沫浸渍法将包钢稀土矿粉末制成多孔陶瓷材料,从而经过实验探究,得到一套面向包钢稀土矿制备多孔陶瓷的配方。实验表明:聚氨酯海绵作有机泡沫体,采用质量分数为20%的NaOH溶液处理,并经质量分数1%的羧甲基纤维素(CMC)处理后,聚氨酯海绵表面粗糙度增加,亲水性能得到了改善,挂浆量也明显增加~[1]。得到相应配方:浆料的固相含量(wt%)为65%,CMC加入量为1%,十二烷基苯磺酸钠加入量为1%,无水乙醇加入量为3%,20%的硅酸钠溶液加入量为30%,PH值控制在10~12左右,可获得高固相含量、均匀稳定、流变性良好、适于浸浆的稀土矿浆料。采用玻璃棒滚压法成型的生坯挂浆均匀,无堵孔现象,成型后的生坯需在60℃下干燥12 h才能进行烧结,实验的最佳烧结温度为1050℃。制得的包钢稀土矿多孔陶瓷结构体脱硝性能良好,孔隙率较高。     

多孔碳化硼成型工艺的研究

利用有机泡沫浸渍工艺制备了孔径为0.5mm左右的碳化硼多孔预制体,研究了海绵表面预处理及固相含量对挂浆量的影响,通过SEM、XRD对制品进行了表面形貌的观查及物相分析,研究表明海绵的预处理可有效提高挂浆量,浆料固相含量在30～35%vol时浸渍效果最佳。     

提高泡沫陶瓷比表面积的工艺研究

采用瓷石、长石、滑石等为原料,以聚氨酯泡沫体为成型体,制备了性能优良的泡沫陶瓷.实验对影响泡沫陶瓷比表面积的相关工艺因素进行了研究.实验结果表明,采用聚丙烯酰胺溶液对聚氨酯泡沫前驱体进行改性,可明显提高挂浆量.同时利用二次挂浆工艺,对素烧后的泡沫陶瓷坯体进行造孔处理,并采用明胶作为气泡稳定剂,可明显提高泡沫陶瓷的比表面积.     

常温固化免烧结泡沫陶瓷复合材料的制备及性能

利用自制的粘结剂,选用合适的填料、悬浮剂和减水剂,表面活性剂等附加剂,采用聚氨酯泡沫塑料先驱体挂浆成形法和常温固化工艺,制备出具有均匀、相互贯通孔结构的免烧结泡沫陶瓷复合材料,其生产工序简单,生产成本低,同时由于聚氨酯泡沫塑料载体保留其中,所以产品韧性好,不易脆断,研究结果表明：随着粘结剂加入量的提高和泡沫塑料载体孔径的减小,泡沫陶瓷复合材料的抗压强度显著增大,但通孔率明显降低es用适当浓度的碱液对泡沫塑料进行表面改性处理,可显著降低其表面张力,提高表面粗糙度,还能溶解残留的封孔薄膜,从增加挂浆量,提高其力学性能,但随着泡沫塑料载体表面改性处理时间的延长,泡沫陶瓷复合材料的通孔率下降bde着常温固化时间的延长,泡沫陶瓷复合材料的抗压强度逐步上升,常温固化28d时,其抗压强度基本上达到最大值。     

聚碳硅烷低温制备碳化硅泡沫陶瓷

采用具有连通气孔的聚氨酯海绵浸渍聚碳硅烷（polycarbosilane,PCS）、碳化硅微粉与四氢呋喃配制的浆料,挂浆素坯经热氧化不熔化处理后,在惰性气氛中于1 000℃热解制备碳化硅泡沫陶瓷。研究了固相含量和PCS含量对碳化硅泡沫陶瓷微观结构、体积密度、线收缩率和抗弯强度的影响,结果表明：固相含量为43.1%～69...     

泡沫陶瓷过滤器用聚氨酯网状海绵的应用研究

本文简单介绍了聚氨酯泡沫海绵的分类,阐述了泡沫陶瓷过滤器用聚氨酯海绵载体的性能指标要求。对比了氧化锆、碳化硅和氧化铝泡沫陶瓷过滤器分别所需聚氨酯海绵性能指标;通过试验发现,不同材质的泡沫陶瓷过滤器所需聚氨酯海绵的强度、弹性、比重、熔点等指标性能也不一样。其中,氧化锆材质泡沫陶瓷过滤器对聚氨酯海绵强度和弹性要求最高,其次碳化硅质、氧化铝质泡沫陶瓷过滤器。试验还发现,聚氨酯海绵性能对泡沫陶瓷产品收缩、通孔率和强度有较大影响,其中通孔率影响最大。     

金属过滤器用高性能碳化硅泡沫陶瓷的制备

介绍了一种适用于大规模工业化生产高强度金属过滤用碳化硅泡沫陶瓷的方法。采用商用SiC粉体和聚氨酯泡沫通过2次挂浆工艺可以制备出最大平均抗弯强度达到2．87 MPa,平均孔径在3 mm左右,同时具备优良的抗热震性能和高达1700℃耐火度的碳化硅泡沫陶瓷。探讨了浆料的牯度、流变性能对挂浆性能的影响及第2次挂浆对强度的增强机理,说明1次浆料的触变性能和适当固相含量的2次浆料是高强度泡沫陶瓷制备的关键,而2次挂浆工艺对强度提高的主要贡献来源于第2次浆料对1次挂浆烧结后留下空洞的有效弥补。     

二次挂浆工艺对铸造用SiC基泡沫陶瓷性能的影响

采用有机前驱体浸渍法制备SiC基泡沫陶瓷过滤器。研究了一次挂浆后的坯体分别经烘干和预烧后进行二次挂浆,制备的泡沫陶瓷在质量增加和抗热震性方面的差异,以及预烧温度对质量增加和抗热震性的影响。结果表明:1)二次挂浆制备工艺制备的SiC基泡沫陶瓷的室温抗压强度明显高于一次挂浆工艺制备的,但抗热震性又明显低于一次挂浆的。2)对二次挂浆制备的泡沫陶瓷,无论是相同的浆料二次挂浆还是不同浆料同样挂浆量挂浆,烘干后直接进行二次挂浆制得的SiC基试样的热震次数要远高于经预烧后进行二次挂浆制得试样的。3)对预烧后二次挂浆制备的泡沫陶瓷,预烧温度越高,其抗热震性越差。     

A modified method of nitric acid pulping of bagasse

Pulping of bagasse by a rapid and mild nitric acid process was successfully carried out to produce different grades of pulp. Nitric chemimechanical bagasse pulp was produced in a high yield of 91 % on pulping depithed bagasse with 4% HNO₃ for a period of 30 min at 80°C, followed by alkali pulping with 2% NaOH at 95°C for 30 min. The pulp had a satisfactory strength and high opacity. On increasing the strengths of nitric acid to 7% and alkali to 7% a nitric semichemical pulp of 65% yield was obtained. The pulp had a superior strength and high opacity. The pulp was easily bleached to 71% general electric brightness (GE) with the chlorination-alkali-extraction-hypochlorite (CEH) sequence. With 15% HNO₃ and 8% NaOH, nitric chemical bagasse pulp was produced. The pulp was easily bleached to a high brightness of 82% GE with one stage hypochlorite. The pulp had a higher strength than kraft bagasse pulp. A satisfactory newsprint paper was produced on an experimental paper machine with a furnish composed of 80% bleached nitric semichemical bagasse pulp, 10% bleached softwood pulp and 10% clay.     

Rapid nitric acid cooking of rice straw

A rapid and mild nitric acid pulping of rice straw was developed and different grades of pulp were produced. A satisfactory nitric chemimechanical rice straw pulp was obtained in a yield of 80% by two stage pulping. In the first stage 5% HNO₃ was used at 80°C and a 6:1 liquor ratio for 30 min, followed by a second alkali stage, 3% NaOH at 95°C for 30 min. The pulp had a satisfactory strength and high opacity and it was bleached by an HP sequence to a 67% general electric brightness (GE). Semichemical pulp of 65% yield was produced by cooking with 10% HNO₃ and 10% NaOH at 20:1 liquor ratio. The pulp had superior strength and it was bleached to a 61% GE by a chlorination-alkali extraction hypochlorite (CEH) sequence. Nitric bleached chemical pulp of 48% and 82% GE was produced by cooking with 6% HNO₃ and 7% NaOH at 10:1 liquor ratio and bleached by a CEH sequence. The chemical pulp is of higher yield and strength than soda pulp. Newsprint that fulfils all the requirements was produced on an experimental paper machine from a furnish composed of 80% bleached nitric chemimechanical rice straw pulp, 10% bleached softwood pulp and 10% clay.     

Dissolution of Lignin from Kraft Pulp after Treatment with Nitrogen Oxides

Laboratory experiments show that pretreatment with NO₂ including heating and ripening at 5% consistency and 90°C for 3 hours in the presence of NO₃- and H⁺ led to a dissolution of approximately 50–60% of the lignin in unbleached kraft pulp. Only 5–15% were dissolved when the treatment was terminated after heating to 90°C. An extensive fragmentation of the lignin during the ripening explains the extensive delignification in acid medium.

Fractionated dissolution of the remaining lignin by alkaline extraction gave fractions with small variation in N-contents (2.9–3.4%) and hydrophilicity. The last fraction exhibited the highest sorption of water vapor. The delignification was related to the decrease in molecular size during the pretreatment and during the subsequent alkaline treatments.     

Preparation of Sebacic Acid via Alkali Fusion of Castor Oil and its Several Derivatives

Castor oil and its three derivatives including methyl ricinoleate, sodium ricinoleate and ricinoleic acid were used as the raw material for alkali fusion to prepare sebacic acid. The reaction parameters including catalyst, ratio of oleochemicals/NaOH, reaction time and reaction temperature were optimized. It was found that Pb₃O₄ (1%) showed the best catalytic performance, and 553 K was considered as the most suitable reaction temperature. The oleochemicals/NaOH ratios of 15:14, 15:14, 15:12 and 15:14 were determined as the optimal ratio for alkali fusion of castor oil, methyl ricinoleate, sodium ricinoleate and ricinoleic acid, respectively. In addition, the optimal reaction time of alkali fusion of castor oil was 5 hours, and that of its derivatives was 3 hours. The maximum yield in sebacic acid of 68.8%, 77.7%, 80.1%, 78.6% can be obtained by using castor oil, methyl ricinoleate, sodium ricinoleate and ricinoleic acid as the raw material, respectively. High purity of sebacic acid was confirmed by GC and melting point analysis. ICP-OES results illustrated that the content of Pb in sebcic acid was less than 1 mg kg⁻¹. Separating glycerol from castor oil was beneficial for alkali fusion, by which, the yield of sebacic acid was increased of approximately 10%, and the reaction time was reduced from 5 to 3 hours. This study provided guiding significance for the future industrial production of sebacic acid.     

一种新型非离子水性聚氨酯的合成

以甲苯二异氰酸酯(TDI)、聚乙二醇(PEG)、聚乙二醇单甲醚(MPEG-1000)和乙二醇(EG)为基本原料,合成了一种新型非离子型水性聚氨酯。对其进行了红外光谱分析、粒径分析和耐酸碱盐试验,并讨论了反应温度、反应时间和MPEG-1000的量对合成反应的影响。结果表明:在70℃下,添加8%(质量分数)的MPEG-1000,反应5 h,合成的非离子水性聚氨酯性能最好。     

麦草亚铵法氧脱木素浆的短流程漂白

对麦草亚铵法氧脱木素浆进行了P、HP和HQP漂白对比研究,结果表明:在过氧化氢单段漂白时,Na2SiO3的适宜用量为0.4%,在所选过氧化氢用量、NaOH用量、温度和时间的四因素三水平方差分析漂白工艺中,影响纸浆白度的主要因素为NaOH用量;而采用HP和HQP漂白时,漂白浆的白度分别达到78.1%(ISO)和81.9%(ISO),可见采用螯合处理的效果明显。     

Was pretreatment beneficial for more biogas in any process? Chemical pretreatment effect on hydrogen–methane co-production in a two-stage process

The study focused on the mesophilic anaerobic hydrogen production from PPS (pulp and paper sludge) and FW (food waste) pretreated by NaOH or H₂SO₄, and the subsequent thermophilic anaerobic methane production with the effluent in a two-stage process. The maximum hydrogen yield (78.35 mL g^?1 VS_fed) which was 50.21% higher than that of CK, was achieved when 10 g NaOH/100 g TS_substrate was used. However, the maximum methane yield (383.8 mL g^?1 VS_fed) was obtained in CK as well as 64% SCOD removal efficiency was achieved. In short, NaOH/H₂SO₄ pretreatment was suitable to enhance the hydrogen production.     

Concentration of acetic acid in sulfite pulp evaporation drain by reverse osmosis

The evaporation drain of sulfite pulp spent liquor contains few volatile fatty acids, most of which is acetic acid. The main objective of this study is to recover acetic acid as the concentrated solution (about 4%), which could be used as a culture medium of the yeast. As acetic acid can easily pass through the cellulose acetate membrane, SP drains neutralized by NaOH, NH₄OH and Ca(OH)₂ were used as the feed solutions. In all cases, concentration by reverse osmosis was successfully carried out provided the appropriate pretreatment was employed. The recovery of acetic acid was 95.6, 90.5 and 98.2% for Na-, NH₄-, and Ca-drain, respectively. In addition, the recovered (permeated) water may be used as an industrial one.     

Characterization of the Residual Kraft Pulp Lignin In Situ by Sulfite Treatments

Abstract

The O₂ delignification of kraft pulps from Norway spruce was shown having a significant impact on the reactivity of the residual pulp lignin as revealed from their responses to sulfite treatments at pH 7.5. A substantial higher ratio of lignin sulfonation to the phenolic hydroxyl group content of residual pulp lignin was observed for the O₂ -delignified kraft pulps (～ 0.8) as compared to a value of ～ 0.3 for the unbleached samples and ～ 1 for the spruce wood lignin. Under the prevailing sulfite treatment conditions, the sulfonation would be largely attributed to the phenolic lignin component and the etherified structures containing an α -carbonyl or -unsaturated group. The contribution from the latter units, evaluated by a borohydride pretreatment of pulps prior to the sulfite treatment, can only account for approximately 15% of the sulfonation observed for the O₂ -delignified sample. Thus, the nature of phenolic structures in the O₂ -delignified pulps was more similar to that of the wood lignin than that of the kraft pulps.     

Enzymatic saccharification of lignocellulosic materials after treatment with supercritical carbon dioxide

Lignocellulosic materials, such as agricultural residues, are abundant renewable resources for bioconversion to sugars. The sugar cane bagasse was studied here to obtain simple sugars for the production of alcohols and other chemicals. The crystalline structure of cellulose and the lignin that physically seals the surrounding cellulose fibers makes enzymatic hydrolysis difficult by preventing the contact between the cellulose and the enzyme. Two different samples of sugar cane (bagasse pulp and skin) were used and compared with microcrystalline cellulose (Avicel). The investigated samples were pretreated with SC-CO₂ explosion before hydrolysis. The experiments were conducted at 12, 14 and 16 MPa at a temperature of 60 °C. In this process, particles of celluloses within the size range from 0.25 to 0.42 mm were placed in defined amounts inside the experimental vessel, CO₂ was injected and let stand for 5 and 60 min. The explosion pretreatment of cellulosic materials by SC-CO₂ was performed in an apparatus of a static type with 300 ml of volume. The hydrolysis reaction using cellulose enzyme was carried at 55 °C for 8 h. After the pretreatment, the glucose yield increased in 72% to the bagasse sample. The SC-CO₂ pretreatment together with alkali increased the glucose yield in 20% as compared with alkali only. X-ray, microscopy and thermal analysis were used to investigate the effect of the pretreatment.