竹炭-ZnO复合材料的制备及对苯酚的光催化降解作用

以硅酸钠为粘结剂用浸涂法制备了竹炭-ZnO复合材料,用FT-IR、电镜扫描(SEM)对其进行结构表征和形貌观察,研究了该复合材料对溶液中苯酚光催化降解去除效果.结果表明:制备竹炭-ZnO复合材料的最佳配比为m(竹炭) ∶m(ZnO)∶m(Na2 SiO3·9H2O) 为5∶2∶1;酸性条件下,竹炭-ZnO复合材料对苯酚的去除效果更好,H2 O2对苯酚溶液光催化降解有促进作用.当苯酚溶液的质量浓度为50mg/L时,复合材料最佳用量为2g/L,溶液中H2 O2最佳的添加量为1.95mmol/L,在紫外灯和太阳光下催化降解4h,苯酚去除率分别达到92.3%和76.4%.复合材料重复使用3次,对苯酚的去除率仍可以达到80%以上.     

光催化复合材料在木质材料上的应用前景

纳米二氧化钛作为一种光催化材料,可以通过光催化反应将多种有害气体污染物降解为CO2、H2O等物质.介绍了TiO2的光催化机理,对纳米TiO2复合材料的研究现状及其在空气净化领域的应用进行了归纳总结,并就光催化复合材料在木质材料上的应用前景进行了可行性分析.     

粉末竹炭的电阻率及与EVA复合材料电磁屏蔽效能探索

采用高速粉碎法制备粉末竹炭,对其电阻率进行测试,并研究了竹炭/EVA不饱和树脂复合材料的电磁屏蔽效能。结果表明,粉末竹炭的粒径大小对竹炭的电阻率有明显影响,随竹炭粒径减少呈现先递减后增加的变化规律,100目时竹炭的电阻率达到最小,其值为6.4×105Ω·cm。竹炭/EVA不饱和树脂复合材料的电磁屏蔽效能超过23.4 d B,厚度4 mm时电磁屏蔽效能最大达48.5 d B。     

竹炭/石墨/环氧树脂电磁屏蔽复合材料性能研究

为研究天然石墨和合成石墨在不同竹炭质量分数条件下复合材料的电磁屏蔽效果,制备屏蔽效能优异的竹炭/石墨/环氧树脂电磁屏蔽复合材料,在两种石墨中分别加入不同质量分数的竹炭,通过模压固化成型制成竹炭/石墨电磁屏蔽复合材料,并对其进行力学性能、动态热机械性能、电阻率性能和电磁屏蔽效能测试及扫描电子显微镜分析。结果表明:随着竹炭质量分数的增加,逐步形成竹炭-石墨网状结构,两种复合材料的玻璃化转变温度均上升;电阻率均降低;30~1 500 MHz频率下电磁屏蔽效能均增大,竹炭质量分数为40%时,合成石墨复合材料电磁屏蔽效能最大,约为30 d B;但由于填料的团聚作用,两种复合材料的弯曲模量下降。扫描电子显微镜分析表明,合成石墨复合材料的界面结合力更好。综合分析可知,当竹炭质量分数为30%时,合成石墨复合材料的力学性能较好;竹炭质量分数增加,石墨复合材料的电磁屏蔽效能增大。     

活性竹炭负载TiO_2及其对苯酚的吸附降解

以活性竹炭(ABC)为基体,通过溶胶浸渍的方法获得了TiO2/ABC材料,并研究了对苯酚的吸附降解。结果表明:活性竹炭上负载的TiO2的物相和晶粒大小跟热处理温度有关。活性竹炭负载TiO后吸附能力变化不大,但赋予了其一定的光催化能力。     

炭含量对竹炭/高密度聚乙烯复合材料电磁屏蔽和力学性能的影响

为了探究竹炭含量对竹炭基复合材料性能的影响,以竹炭(BC)和高密度聚乙烯(HDPE)为原料,采用"熔融挤出-模压"成型工艺制备竹炭/高密度聚乙烯(BC/HDPE)复合材料,通过对不同竹炭含量的BC/HDPE复合材料进行测试,研究炭含量对复合材料力学性能、热性能、电磁屏蔽性能以及微观结构的影响.结果表明,竹炭对BC/HD...     

TiO2/木材复合材料光催化降解甲醛性能

【目的】光催化氧化法被认为是去除室内空气中甲醛最有效的方法之一。二氧化钛(TiO₂)作为经典光催化半导体,因具有物理化学性质稳定、无毒无害的优点被广泛关注,但由于TiO₂的吸附能力低、聚集倾向强,限制了其应用。本研究旨在解决TiO₂吸附能力弱、易团聚使其比表面积减小的问题。【方法】以杨木为基底,采用水热法在其表面负载二氧化钛制备得到TiO₂/木材复合材料,探讨不同TiO₂溶液浓度对TiO₂/木材复合材料光催化降解甲醛性能的影响。【结果】与不同基底对比,木材的多孔结构及丰富的官能团能使TiO₂与木材间具有更好的结合力,使其具有优越的机械稳定性。锚定在木材上的TiO₂以锐钛矿型为主并带有少量的金红石型。随着TiO₂溶液浓度的增大,TiO₂/木材复合材料的光催化降解甲醛性能呈现先增大后减小的趋势。当配置制备的TiO₂溶液浓度为0.1 mol/L时,尺寸大...     

二氧化钛/壳聚糖/丙烯酸复合水凝胶的原位交联及性能

壳聚糖基复合材料在水凝胶领域应用广泛,但其制备过程中通常需要有毒性的化学交联剂和经过繁琐的化学修饰等过程。将壳聚糖、丙烯酸和钛酸四丁酯共混,在遇水后,通过钛酸四丁酯的原位水解形成的纳米二氧化钛作为物理交联剂,一步法制备复合水凝胶,过程简单且无需化学交联剂。在此复合水凝胶中,纳米二氧化钛作为交联剂和光催化剂,丙烯酸可以提高壳聚糖的吸水性,同时丙烯酸和壳聚糖表面的羟基和氨基等基团又可以增强二氧化钛的光催化性能。利用X射线衍射、傅里叶红外光谱、扫描电镜和透射电镜等考察其形貌与结构等特征,并通过吸水试验和亚甲基蓝的光降解试验测试了其溶胀及光催化性能。结果表明:该复合水凝胶内部为多孔结构,粒径约为5~12 nm的二氧化钛均匀分散在复合水凝胶中,无团聚现象。该复合水凝胶材料具有优良的吸水性,其饱和吸水率约为1500%,在模拟自然光下对亚甲基蓝有较好的光催化降解效果。以上结果表明该材料在污水处理领域具有一定的应用前景。     

竹炭吸附铜唑对竹塑复合材料防护性能的影响

研究了高温浸泡、超声浸渍和高压浸渍三种吸附方式下竹炭(BC)对铜唑(CuAz)吸附容量的影响,优选出理想的吸附方式后将高铜唑吸附容量的竹炭添加至竹塑复合材料中,研究其对竹塑复合材料的防霉防腐性及抗流失性的影响。结果表明:三种吸附方式下,高温浸泡的吸附效果最好。吸附温度为70℃,吸附时间为24 h,铜唑初始浓度为2.8%时,竹炭吸附铜唑容量达到最大值59.9 mg/g。将吸附了铜唑的竹炭添加至竹塑复合材料中,能提高材料对黑曲霉、绿色木霉、桔青霉的防治效力,但是对蓝变菌几乎没有影响;能减少白腐菌侵蚀后材料的质量损失,但对褐腐菌无明显影响。竹炭吸附铜唑的处理方式能有效地提高铜唑在竹塑复合材料中的抗流失性,延长铜唑防腐剂的药效时间。     

竹炭/环氧聚酯复合材料的电磁屏蔽性能研究

采用高速粉碎法制备粉末竹炭,使用热压成型制备竹炭/环氧聚酯复合材料,研究了复合材料的电磁屏蔽效能。结果表明,环氧聚酯含量对复合材料电磁屏蔽性能的影响明显,电磁屏蔽效能随环氧聚酯含量的增加而降低;2 mm厚的复合材料电磁屏蔽效能超过21.2 d B,最高达36.8 d B。     

外负载TiO2功能化改性木材研究现状

TiO₂作为一种新型无机纳米改性剂,对于改善木材尺寸稳定性差、易燃、易朽、不耐虫蛀、易变色、耐老化性差等缺点,赋予其新的功能性具有良好的效果。文中主要对比了TiO₂负载木材的方法,即表面涂覆、水热法、溶胶—凝胶法和超声波辅助溶胶—凝胶法的机理和优缺点;分析了TiO₂改性对木材内部构造及微观结构的影响,归纳了TiO₂改性对木材吸湿性和力学性能的影响;概述了TiO₂在防水、阻燃、防腐、耐候、防变色、光催化和亲疏水双面功能型木材及磁吸附木材中的应用研究现状;归纳总结了TiO₂在改性木材科学研究中存在的问题,并提出合理建议,以期为实际生产和科学研究提供参考。     

Photocatalytic activity of TiO<Subscript>2</Subscript> crystallite-activated carbon composites prepared in supercritical isopropanol for the decomposition of formaldehyde

 An effort was made to develop photocatalytic TiO₂ crystallite–activated carbon (TiO₂-AC) composites from tetraisopropyl titanate (TPT)-soaked activated carbon in supercritical isopropanol. It was subsequently found that TPT in supercritical isopropanol could be effectively converted to the anatase form of the TiO₂ crystallites. The prepared composites, composed of activated carbon as an adsorbent and the anatase form of TiO₂ as a photocatalyst, were evaluated for their adsorption capacity and subsequent photocatalytic activity against formaldehyde, one of the harmful air pollutants in the environment. As a result, the supercritically treated TiO₂–AC composites, particularly at 300°C and 350°C, had much higher formaldehyde-decomposing ability compared to a noncomposite comprising a simple mixture of activated carbon and TiO₂ granules. This indicates that the supercritical treatment can be effective for preparing the photocatalytic composites that have a high synergetic effect of adsorption and photocatalytic decomposition of formaldehyde for environmental cleaning. Received: May 18, 2001 / Accepted: March 8, 2002 On leave from Fujian Forestry College, Fujian 353001, P.R. China Acknowledgments The authors express their sincere thanks to Miss H. Tokoro and Mr. D. Kusdiana for their kind, valuable help and cooperation and to Dr. H. Miyafuji for SEM observations of samples, all at the Graduate School of Energy Science, Kyoto University. Correspondence to:S. Saka     

TiO2在木材工业中的应用与展望

介绍TiO2光催化性能的基本原理,并在综合分析文献的基础上,总结国内外木材工业中TiO2的应用研究现状,指出:TiO2优异的环境特性和使用性能尚未被木材工业很好地研究和利用,在制备多功能型环保材料、抗紫外线材料和性能增强型材料等方面应用前景广阔.     

Carbon and nitrogen in forest soils: Potential indicators for sustainable management of eucalypt forests in south-eastern Australia

Soil organic matter (SOM) has been adopted as an indicator of soil fertility based on the rationale that SOM contributes significantly to soil physical, chemical, and biological properties that affect vital ecosystem processes of forests in Australia. A study was undertaken to evaluate the utility of SOM as an indicator of SFM at two long-term experimental sites in native eucalypt forests, including Silvertop Ash (E. sieberi L. Johnson) and Mountain Ash (E. regnans F. Muell.) in Victoria. This study examines the relative contributions made by various sources of carbon in soil profiles (0–30 cm) of forest soils, viz. mineral soil (<2 mm), plant residues, charcoal (>2 mm), and rock fragments (>2 mm). The long-term changes in these fractions in response to management-induced soil physical disturbance and fire (unburnt, moderate and high intensity) were evaluated. After 10 years, carbon levels in the fine soil fraction (soil <2 mm including fine charcoal) were similar across the range of fire disturbance classes in Mountain Ash forest (20–25 kg/m²) and Silvertop Ash forest (7–8 kg/m²). Likewise differences in carbon associated with other fractions, viz. microbial biomass, labile carbon, plant residues and rock fragments were comparatively small and could not be attributed to fire disturbance. Burning increased the charcoal carbon fraction from 5 to 23 kg/m² in Mountain Ash forest and from 1 to 3 kg/m² in Silvertop Ash forest. Taking into account, the percentage area affected by fire, increases in total soil carbon in these forests were estimated at 25 and 7 t/ha, respectively.

The effects of physical disturbance of soils were examined at one site in Mountain Ash forest where soil cultivation was used as site preparation rather than the standard practice of burning of logging residues. Total carbon in soil profiles decreased from 29 to 21 kg/m² where soil disturbance was severe, i.e. topsoil removed and subsoil disturbed. This was mainly due to a decrease in charcoal carbon from 6.8 to 1.7 kg/m² but severe soil disturbance also increased the amount of carbon associated with rock fragments from 1.6 to 3.5 kg/m².

Management-induced fire increased the coarse charcoal content of soil profiles substantially, thus increasing total carbon content as well as the proportion of recalcitrant carbon in SOM. In contrast, there was little change in the carbon content of the fine soil fraction including the labile and biologically active fractions indicating that these SOM fractions most relevant to ecosystem processes showed little long-term impact from soil disturbance and fire. Conventional sampling of the fine soil fraction (<2 mm) only represented between 50% and 70% of total carbon in the soil profiles. In contrast, total nitrogen in this fraction represented between 75% and 90% of the nitrogen in soil profiles and was less affected by changes in the contributions of N made by coarse fractions. Monitoring of soil N rather than C as an indicator of soil fertility and SFM may be more appropriate for forest soils with significant charcoal content.     

Burning of Amazonian forest in Ariquemes, Rondônia, Brazil: biomass, charcoal formation and burning efficiency

Biomass burning in tropical forests – the normal practice to prepare land for agriculture and ranching – has been a major source of CO₂ emitted to the atmosphere. Mass transformations by burning are still little studied in the tropics. The present study estimated parameters, such as the stock of carbon contained in the biomass, burning efficiency and the formation of charcoal and ashes in a tropical moist forest. Two sets of plots arranged in the form of ‘stars' (720 m² total) were installed in a 3.5 ha area of forest that had been felled for planting pasture at Fazenda Nova Vida, Ariquemes, Rondônia. Each ‘star' had six rays measuring 2 m × 30 m; alternating rays were designated for pre-burn and post-burn measurements. All above-ground biomass present in the plots was weighed directly before the burn in the pre-burn rays and after the burn in the post-burn rays. Pieces of wood with diameter ≥10 cm also had their biomasses estimated from volume estimates, using line-intersect sampling (LIS) in order to increase the area of sampling and to allow volume loss to be estimated as an increment based on individual pieces measured before, and after, the burn at the same point (as opposed to inferring change as a difference between independent estimates of stocks). The initial above-ground biomass (dry weight) before the burn was estimated at 306.5 ± 48.6 (mean ± SE) Mg ha⁻¹, with an additional 4.5 Mg ha⁻¹ for trees left standing. Carbon stock in the initial biomass (including trees left standing) was 141.3 (Mg C) ha⁻¹. After burning, carbon stock was reduced by 36.8% (burning efficiency). The stocks of charcoal and ash formed in the burn were, respectively, 6.4 ± 2.7 and 5.7 ± 1.0 Mg ha⁻¹. The destructive and nondestructive (LIS) methods did not differ significantly (t-test, p > 0.05) in estimating post-burn stocks of wood and charcoal. The results of this study contribute to improving the estimates of parameters needed for global carbon calculations and point to ways in which estimates of these parameters could be further improved.     

Supercritically treated TiO2-activated carbon composites for cleaning ammonia

Supercritically treated TiO₂-activated carbon (Sc-TiO₂-AC) composites were studied for their adsorption and photocatalytic activities toward gaseous ammonia (NH₃). The experiments were carried out at 26°C using a black lamp. The Sc-TiO₂-AC composites attained higher photocatalytic activities than supercritically treated TiO₂ (Sc-TiO₂). NH₃ was found out to be converted by the Sc-TiO₂-AC composites to compounds such as N₂, N₂O, NO₂ ⁻, and NO₃ ⁻. The main product was harmless N₂. The Sc-TiO₂-AC composites are expected to be applied as effective cleaning materials to environments that emit offensive NH₃ odors.     

TiO2/核桃壳炭复合材料的制备及光催化降解苯酚研究

为提高TiO2的回收性能,促进农林废弃物的资源化利用,以核桃壳为炭源,采用溶胶 凝胶法制备TiO2/核桃壳炭复合材料。通过傅里叶红外光谱、X射线衍射、比表面积和电镜扫描等手段对复合材料的化学和晶相结构、比表面积和微观形貌进行表征,并测试其对苯酚的吸附 光催化性能。物相表征结果显示,TiO2/核桃壳炭(400℃,2 h)中TiO2以锐钛矿相颗粒分散在核桃壳炭表面,炭的固载提高了TiO2的分散性能,使其晶粒尺寸由15.7 nm降低至11.6 nm,增强了可见光吸收能力。活性分析结果表明:当TiO2含量为80%,催化剂用量为2 g/L,苯酚初始质量浓度为10 mg/L,紫外光照射240 min时,TiO2/核桃壳炭(400℃,2 h)对苯酚的降解率为97.7%,化学需氧量降解率为92.36%,优于TiO2(分别为71.55%和63.34%)和商业购买的平均粒径为25 nm的锐钛矿晶和金红石晶混合相的TiO2(降解率88.56%),且几乎完全矿化,符合一级反应动力学方程。TiO2和TiO2/核桃壳炭光催化降解苯酚的主要活性中心分别为·OH和·O-2,核桃壳炭的负载提高了TiO2吸附 光催化苯酚性能和回收效率。     

竹剩余物资源化利用研究现状与展望

竹材在利用过程中能产生60%～70%的剩余物,但未得到合理利用,造成严重的资源浪费和环境污染,将竹剩余物进行资源化利用可以提高竹材利用率和附加值。文中从竹剩余物的综合利用角度出发,综述了利用竹加工剩余物制造竹材人造板、竹塑复合材、竹炭、竹醋液、生物质能源、竹提取物等多种竹产品的研究现状,重点介绍竹剩余物资源化利用的研究进展及最新研究成果、竹剩余物产品的制作方法及机理,以期为今后竹剩余物高质、高效利用提供参考。