不同黏结剂组合甘蔗渣/麦秆碳复合材料制备与性能研究

该文以甘蔗渣、麦秆为原料,以酚醛树脂、羧甲基纤维素为黏结剂,采用混合后热压再烧结的工艺制各碳复合材料,试验制备了各温度点下的材料并对其残碳率、密度、气孔率、强度、电阻率等性能进行了测试,对该材料的性能、形成机理及规律进行了分析,初步揭示了原料选择、配比、温度等参数对整个制备过程及复合材料性能的影响.试验结果证明:通过该工艺用甘蔗渣(麦秆)和酚醛树脂(羧甲基纤维素)制备复合材料可行的,同时也表明黏结剂和烧结温度对碳复合材料性能影响很大,该试验为甘蔗渣(麦秆)等植物残渣的利用开辟了新的途径.     

升温模式对木质陶瓷性能的影响

以麦秸为原料，采用混合后热压再炭化的工艺制备出木质陶瓷，通过实验观察分析升温模式对其残碳率、密度、气孔率、抗弯强度、电阻率等性能的影响。结果表明降低升温速率并在关键温度点保温炭化后，木质陶瓷的真密度、气孔率、抗弯强度提高，电阻率下降，尤其是残碳率提高显著。该文提出了一种全新的木质陶瓷制备工艺，对传统的升温模式进行了改进，为麦秸的综合利用探索了新的方向。     

阻燃剂对作物秸秆木质陶瓷残碳率的影响

木质陶瓷是一种功能性木质炭素新材料,残碳率是木质陶瓷的一个重要指标,论文试图选择合适的阻燃剂以提高木质陶瓷的残碳率。试验选取了麦秸、热固型酚醛树脂、酒精等为原料,氯化锌、碳酸钾、磷酸氢二氨以及硼砂等为阻燃剂,按照一定的比例混合均匀并热压成一定尺寸的坯体,再将坯体在氮气保护下按两种升温模式分别烧结至300℃、400℃、500℃、600℃、700℃和800℃,制备出各温度点下的木质陶瓷,观察分析了阻燃剂对其残碳率的影响。结果表明,与对照组比较,添加适量的阻燃剂后,在两种升温模式下,木质陶瓷的残碳率分别提高了大约6%和10%,而其抗弯强度、密度、显气孔率及电阻率等性能没有受到影响。结果证明了通过此工艺用麦秸制备木质陶瓷的可行性,同时表明了氯化锌、碳酸钾、磷酸氢二氨以及硼砂等阻燃剂对木质陶瓷残碳率提高的良好效果,试验结果也为麦秸的综合利用开辟了新的方向和空间。     

硅藻土微孔陶瓷灌水器制备工艺优化

为解决现有微孔陶瓷灌水器制备成本较高、产品性能低下,不利于大面积推广和应用的问题,该文以黏土、硅藻土和硫酸钙为主要原料,探索一种微孔陶瓷灌水器的低成本制备工艺。分析了硅藻土掺量和烧结温度2个因素对微孔陶瓷线收缩率、开口孔隙率、维式硬度、渗透系数和微孔陶瓷灌水器流量的影响规律。以线收缩率、维氏硬度、开口孔隙率、渗透系数和流量为指标,优选出微孔陶瓷灌水器的最佳制备工艺。结果表明:硅藻土掺量增加,或烧结温度降低,会使得微孔陶瓷的线收缩率和维氏硬度降低,开口孔隙率和渗透系数增大,进而使得微孔陶瓷灌水器的流量增大。综合比较,1 075℃烧结的硅藻土掺量质量分数为15%的微孔陶瓷灌水器,线收缩率为4.9%、开口孔隙率为26.3%、维氏硬度为448 MPa,在10 k Pa的工作压力下流量为1.64 L/h,兼备良好的力学性能和水力性能,是制备微孔陶瓷灌水器的最佳工艺。该研究为微孔陶瓷灌水器的制备和性能优化提供了参考。     

机械活化预处理甘蔗渣制备醋酸纤维素的工艺

为开发利用甘蔗渣,制备高取代度的醋酸纤维素,该文采用自制搅拌磨对甘蔗渣进行机械活化预处理,以不同活化时间的甘蔗渣为原料,醋酸酐作为乙酰化剂,浓硫酸为催化剂,制备醋酸纤维素。以醋酸纤维素的取代度为评价指标,分别探讨机械活化时间、反应时间、反应温度、催化剂用量、液固比等因素对甘蔗渣乙酰化反应的影响,并在此基础上采用正交试验确定制备工艺的最佳条件。结果表明,机械活化对甘蔗渣乙酰化反应具有显著的强化作用,经机械活化预处理后的甘蔗渣比原甘蔗渣更容易进行乙酰化反应。主要的原因是机械活化破坏了甘蔗渣中木素对纤维素的包裹作用,结晶结构受到破坏,降低纤维素的结晶度,乙酰化试剂更容易渗透到甘蔗渣内部使纤维素发生乙酰化反应,降低了对反应时间、反应温度、催化剂用量、液固比的依赖性,提高了反应活性。以活化60min的甘蔗渣为原料进行乙酰化反应,在液固比为12 mL/g,催化剂质量分数为4%,反应温度为60℃,反应时间为3.0h的条件下,可制得取代度为2.81的醋酸纤维素。并采用红外光谱（IR）、扫描电镜（SEM）、X-射线衍射（XRD）对甘蔗渣醋酸纤维素的结构进行了表征。研究结果将为制备高取代度醋酸纤维素提供依据和基础数据。     

硅藻土/玉米秸秆木质陶瓷制备及其对废水中四环素吸附动力学

为资源化利用农业废弃物,探求玉米秸秆的高效综合利用。以玉米秸秆和酚醛树脂为主要原料,通过硅藻土改性,制备了硅藻土/玉米秸秆木质陶瓷。结合SEM、XRD、FI-TR、压汞法现代测试手段对样品的结构及性能进行了表征。以四环素为目标污染物,研究了样品对四环素的吸附等温线和吸附动力学。结果表明:经硅藻土改性的木质陶瓷内部含有大量孔洞,以非晶质为主,含有少量石英晶相和结晶石墨。木质陶瓷的孔径范围主要在1 000～3 800 nm,孔隙率约为48.6%,比表面积达到7.83 m2/g。由相关系数R2可知,Langmiur等温吸附模型比Frendlich模型更好地描述了木质陶瓷对四环素(0.9990.975)的吸附过程;pH值为3、5、7、9条件下,以木质陶瓷对初始浓度为5 mg/L的四环素溶液进行吸附。动力学模型拟合结果表明,准二级动力学模型参数R20.98,能够更好地拟合材料对四环素的吸附过程。该研究实现了废弃材料的深度利用和对四环素废水的有效处理,为玉米秸秆的利用提供了新的途径。     

不同生物质炭对海南砖红壤性质及N_2O排放的影响

制备温度及原料影响生物质炭性质,相应影响土壤N_2O的排放,为筛选适宜于海南砖红壤的生物质炭类型,利用室内培养试验,研究海南4种禾本科植物材料在300、500、700℃三种热解温度下制备的12种生物质炭对砖红壤性质及N_2O排放的影响。结果表明:所有生物质炭都能显著增加土壤有机碳、有效磷和速效钾含量,提高土壤pH,加速土壤硝化作用进行;300℃下制备的生物质炭能促进土壤N_2O排放,500℃和700℃下制备的生物质炭则对土壤N_2O排放有明显抑制作用;所有材料中,高温热解温度下由甘蔗渣制备的生物质炭处理土壤的N_2O排放量最低,可能由于甘蔗榨糖后剩下的甘蔗渣以较稳定的碳水化合物为主。综合分析,推荐500℃热解温度下生成的甘蔗渣生物质炭实施土壤改良,更有利于N_2O减排。     

提高淀粉基木材胶粘剂耐水性的工艺优化

为解决淀粉代替石油产品制取胶粘剂胶接木质材料后耐水性差的问题,该研究用玉米淀粉、聚乙烯醇、异氰酸酯和羧基丁苯胶乳等原料合成胶粘剂过程中各因素对胶接后湿强度的影响规律。采用二次旋转正交组合试验方法设计试验,并用SAS软件和Matlab软件处理数据,分析了原料配方和反应温度对胶粘剂胶接木质材料后湿强度的影响,优化了淀粉胶粘剂的工艺参数,淀粉质量分数13%,聚乙烯醇质量分数4%,异氰酸酯质量分数5%,胶乳质量分数3%;反应温度58℃。并通过扫描电子显微镜进行了微观结构分析,揭示了淀粉胶粘剂湿强度提高的机理。     

不同温度下海南禾本科类植物材料制备的生物质炭对 砖红壤性质及N2O排放影响

制备温度及原料影响生物质炭性质,相应影响土壤N₂O的排放,为筛选适宜于海南砖红壤的生物质炭类型,利用室内培养试验,研究海南4种禾本科植物材料在300℃、500℃、700℃ 三种热解温度下制备的12种生物质炭对砖红壤性质及N₂O排放的影响。结果表明：所有生物质炭都能显著增加土壤有机碳、有效磷和速效钾含量,提高土壤pH,加速土壤硝化作用进行;300℃下制备的生物质炭能促进土壤N₂O排放,500℃和700℃下制备的生物质炭则对土壤N₂O排放有明显抑制作用;所有材料中,高温热解温度下由甘蔗渣制备的生物质炭处理土壤的N₂O排放量最低,可能由于甘蔗在榨糖后剩下的甘蔗渣以较稳定的碳水化合物为主。综合分析,推荐500℃热解温度下生成的甘蔗渣生物质炭实施土壤改良,更有利于N₂O减排。     

丙烯酸酯木塑复合材料增容剂的性能及应用

该文以含有双键官能团的硅氧烷和丙烯酸酯类为原料,通过自由基聚合方法,制备了丙烯酸酯类木塑增容剂,采用模压成型工艺制备了甘蔗渣/聚乙烯木塑复合材料,利用万能电子试验和冲击试验机测试其拉伸及冲击性能,结果表明,采用硅烷偶联剂KH-570和甲基丙烯酸缩水甘油酯等丙烯酸酯类的共聚物是较好的木塑复合材料增容剂,其共聚单体中引入的环氧基团可以和氨基硅烷偶联剂的氨基或纤维素中的羟基进行开环交联反应,使木粉纤维和丙烯酸酯类共聚物之间形成交联互贯网络,在甘蔗渣、增容剂和塑料之间形成均匀稳定的微观分散体系,降低了纤维素极性,     

Effect of Palygorskite Clay,Fertilizers, and Lime on the Degradation of Oil Products in Oligotrophic Peat Soil under Laboratory Experimental Conditions

The effect of native palygorskite clay and that modified with dodecyltrimethylammonium chloride on the degradation of oil products in an oligotrophic peat soil under complete flooding at the application of lime and mineral fertilizers has been studied under laboratory conditions. It has been shown that the incubation of oil-contaminated soil with unmodified clay and fertilizers at the application of lime under complete flooding with water affects the dynamics of pH and Eh and slows the development of reducing conditions compared to the use of clay without fertilizers. The addition of organoclay under similar conditions favors the formation of potential-determining system with a high redox capacity, which is capable of retaining the potential on a level of 100–200 mV at pH ～ 7 for two months. It has been found that, under the experimental conditions, unmodified and modified clay, which has no toxic effect on the bacterial complex, does not increase the biodegradation efficiency of oil products in the oligotrophic peat soil compared to the experimental treatments without clay addition. Possible reasons for no positive effect of palygorskite clay on the biodegradation rate of oil products under experimental conditions have been analyzed.     

小麦和燕麦两种作物镁吸收和坡缕石转化能力研究

Weathering of clay minerals is a source of nutrients to plants. Palygorskite is a Mg-rich fibrous clay mineral that commonly occurs in the soils and sediments of arid regions. Although many studies have examined the environmental conditions required for the formation and stability of palygorskite, information on the transformation of this mineral in the root zone (or rhizosphere) of agricultural crops is limited. This study explored the possibility of palygorskite transformation in the rhizosphere of wheat and oat and compared the ability of these crops to extract structural Mg from palygorskite. The crops were cultivated in pots consisting of a mixture of sand from Hamadan region, Iran and Florida palygorskite, irrigated with distilled water, and treated with either complete or Mg-free nutrient solutions. After 100 d, Mg uptake by the crops was measured. Clay-sized particles in each pot were also separated from the sand and were analyzed through X-ray diffraction (XRD). The X-ray pattern of the particles was compared with that of the pure palygorskite particles (before cultivation). The results showed that palygorskite could provide sufficient Mg for the growth of wheat in the pots supplied with Mg-free nutrient solution. In spite of the magnesium uptake by both plants from the palygorskite structure, no detectable peaks indicating the transformation of palygorskite were recognized by XRD. A decrease of 1.05 nm in peak intensity was more obvious for the pots containing palygorskite and irrigated with Mg-free nutrient solution than for the pots irrigated with complete nutrient solution. Although the decrease in peak intensity was greater for oat than wheat, indicating greater palygorskite weathering by oat, Mg uptake by oat was low, as evidenced by the deficiency symptoms observed.     

在伊朗中部源于第三纪沉积物的土壤上影响坡缕石的发生因素研究

Limited information is available on the distribution and origin of palygorskite in soils developed on Tertiary sediments as the major soil parent materials in central Iran and other Middle Eastern countries. The objectives of this study were to determine the distribution and origin of palygorskite in soils developed on Tertiary sediments, and to identify the major soil properties that influence palygorskite distribution in the soils studied. Sixteen soil profiles developed on Paleocene, Eocene, Oligocene, Oligocene-Miocene, Miocene and Pliocene sediments were studied by X-ray diffraction analysis, transmission electron microscope, and scanning electron microscopy. Physicochemical characteristics of the soils and sediments including particle size distribution, pH, electrical conductivity, organic carbon, gypsum, carbonates, and soluble Si, Ca and Mg were determined. The principal component analysis was used to establish the relationships between palygorskite and the physicochemical characteristics of the soils studied. Results showed that clay fraction of all the soils in the study area was dominated by palygorskite. The highest amount of palygorskite was found in horizons where simultaneous accumulation of both carbonates and gypsum occurred. Limited amount of palygorskite was found in salic and calcic horizons. Palygorskite seemed to be of eolian origin in the surface horizon of all the soils. Using principal component analysis, the soluble Mg/Ca ratio, pH, soluble Si and gypsum contents were identified as the most important factors affecting the distribution and genesis of palygorskite in the soils studied. Results might suggest the neoformation of palygorskite by precipitation from solutions in which evaporation fluxes were very high. However, palygorskite in soils developed on Tertiary sediments in central Iran seems to be of both inherited and pedogenic origins.     

Effect of pH on Zinc Adsorption and Solubility in Suspensions of Different Clays and Soils

Zinc solubility in clay and soil suspensions was controlled by chemisorption at pH 4.5 – 7.0. The solubility in clay mineral suspensions was in the order palygorskite < montmorillonite « kaolinite and reflected the high affinity of zinc to palygorskite and the high CEC of montmorillonite. The solubility in soil suspensions was in the order Haplustoll < Torrifluvents and reflected the effect of high CEC and organic matter content of the first. The slopes of the pH-pZn curves, calculated zinc potential and sequential desorption data suggested that Zn⁺⁺ ? Zn(OH)₂ aqueous controlled the solubility of zinc in soil and clay mineral suspensions at pH 7.5 – 9.0. The slopes of the pH–pZn curves of two soils were, however, modified by the possible peptization of organic matter and Zn(OH)₂.     

凹凸棒石吸附铜离子的机理

A single-factor experiment of copper ion adsorption on pure palygorskite was carried out to understand the Cu^2 sorption of palygorskite-an important clay mineral in soil and sedimentary rock. In addition, pH of the solution and the surface microstructure of palygorskite were investigated before and after adsorption. The experimental results indicated that efficiency of Cu^2 removal was related to the oscillation rate of the specimen shaker, sorption time, initial pH value and the amount of adsorbent added. Palygorskite induced Cu^2 hydrolysis and interaction between copper hydroxide colloids and palygorskite surfaces, as observed with transmission electron microscopy (TEM), were the main contributions to palygorskite removal of Cu^2 . This mechanism was different from adsorption at the mineral-water interface. It was proposed that surface hydrolysis of palygorskite raised the alkalinity of the palygorskite-water interface and suspension system. Thus, the induced pH of the solution was then high enough for Cu^2 hydrolysis on the mineral surface and in solution.     

Submicroscopy and stable isotope geochemistry of carbonates and associated palygorskite in Iranian Aridisols

Pedogenic carbonates in arid and semi-arid regions of the world have a great significance as palaeoecological and palaeoclimatological indicators and form a major pool in the carbon cycle. We analysed the ultra-microfabric and the stable isotope composition of C and O in pedogenic carbonates in colluvial soils derived from limestone in an arid region of central Iran. Our objective was to determine the conditions for the formation of soft pedogenic carbonate nodules and their co-existence with palygorskite in the palaeo-argillic horizon. Scanning electron microscopy revealed that the calcite aggregates were matted with palygorskite. Ultra-microtome cuts, examined using transmission electron microscopy, provided more detailed information about the fundamental particle association of secondary carbonates and palygorskite. Although less abundant, other silicate clays were detected in both the acid-insoluble clay fractions and in ultra-cuts, mostly in fine clay size, suggesting the engulfing of palygorskite by growing calcite or illuviation of palygorskite during or after formation of the calcite. Coatings of illuvial clays on calcite crystals support the hypothesis that palygorskite was trapped by pedogenic carbonate when the climate was wetter than it is today to form an argillic horizon. However, electron microscopic evidence of the occurrence of fibres on the immediate pedogenic carbonate particle surfaces suggests the in situ formation of palygorskite. The δ¹³C and δ¹⁸O values of pedogenic carbonates suggest that these carbonates were formed in an environment with more available moisture and more C4 plants than now.     

玄武岩纤维改性大豆蛋白胶黏剂性能及胶合机理

为提高大豆蛋白胶黏剂的胶合强度,开发环境友好型木材用生物质胶黏剂,采用玄武岩纤维(basalt fiber,BF)作为增强改性剂,成功制备了胶接性能优良的玄武岩纤维改性大豆蛋白胶黏剂(basalt fiber/soybean protein isolate adhesive,BF/SPIA),并对BF/SPI的胶接强度、流变特性、化学基团及形态结构进行了分析。研究结果表明:随着玄武岩纤维用量的逐步提高,改性大豆蛋白胶黏剂的力学强度呈先增加后下降的趋势。当BF质量分数为5%时,BF/SPIA干、湿状胶接强度分别达2.15和0.92 MPa。流变特性测试结果表明BF/SPI胶黏剂的剪切模量有所增加;傅里叶红外光谱(fourier infrared spectrum,FTIR)显示出改性大豆蛋白胶黏剂中亲水基团降低,Si—O键特征峰明显,BF与大豆蛋白分子间相互作用,形成新的复合结构;扫描电镜(scanning electron microscope,SEM)图谱印证了BF与SPAI两相体系融合性良好,且固化胶接界面较为致密。中试试验结果进一步表明玄武岩纤维改性大豆蛋白胶黏剂具有良好的稳定性,其湿状胶接强度可高达1.05 MPa,木材压缩率仅14.92%,实用性较强。该研究可为改性大豆蛋白胶黏剂的工业化应用及推动环保木材胶黏剂的应用进程提供理论参考。