热解活化法制备微孔发达椰壳活性炭及其吸附性能研究

以椰壳为原料,采用热解活化法制备微孔发达活性炭。研究了活化温度、活化时间对活性炭孔结构和吸附性能的影响。实验结果表明:活化温度为900℃,活化时间为4 h,可制得比表面积为994.42 m2/g的微孔发达活性炭,其碘吸附值为1 295 mg/g,亚甲基蓝吸附值为135 mg/g。N2吸附结果表明活性炭的平均孔径在2 nm左右,总孔容积为0.503 9 cm3/g,其中微孔容积为0.430 3 cm3/g,微孔率达85.39%。对该活性炭进行CO2动态吸附实验,CO2饱和吸附容量为56.61 mg/g,在热解活化法制备椰壳过程中,随着活化温度的升高和活化时间的延长,活性炭的得率有不同程度的降低。     

氮掺杂木质素基活性炭的制备、表征及其吸附性能研究

以碱木质素(AL)作为原料，KOH为活化剂，壳聚糖(CS)为氮源制备氮掺杂木质素基活性炭(N-LAC),采用SEM、XPS和N₂吸附-脱附等温线等方法对活性炭的结构进行表征，并考察了N-LAC对甲基橙(MO)和亚甲基蓝(MB)的吸附性能。研究结果表明：N-LAC主要由微孔构成，掺氮增大了木质素基活性炭(LAC)的表面孔隙，在制备条件为KOH与AL质量比2∶1、CS添加量(以碱木质素质量计)30%、活化温度800℃、活化时间2 h时，N-LAC的比表面积为1 457.79 m²/g,总孔容为0.789 cm³/g,微孔孔容为0.612 cm³/g,平均孔径为2.165 nm。N-LAC中氮元素主要以吡咯型氮(N-5)和吡啶型氮(N-6)形式存在，氮的掺杂会降低活性炭的石墨化程度。N-LAC吸附MO和MB的吸附动力学结果表明：N-LAC吸附MO符合粒内扩散模型，以表面吸附为主；N-LAC吸附MB符合准二级动力学模型。     

Preparation and Adsorption Properties of Activated Carbon with Developed Micropore from Coconut Shell by Pyrolysis Activation

以椰壳为原料,采用热解活化法制备微孔发达活性炭.研究了活化温度、活化时间对活性炭孔结构和吸附性能的影响.实验结果表明:活化温度为900℃,活化时间为4h,可制得比表面积为994.42 m2/g的微孔发达活性炭,其碘吸附值为1 295 mg/g,亚甲基蓝吸附值为135 mg/g.N2吸附结果表明活性炭的平均孔径在2nm左右,总孔容积为0.503 9 cm3/g,其中微孔容积为0.430 3 cm3/g,微孔率达85.39％.对该活性炭进行CO2动态吸附实验,CO2饱和吸附容量为56.61 mg/g,在热解活化法制备椰壳过程中,随着活化温度的升高和活化时间的延长,活性炭的得率有不同程度的降低.     

木质颗粒活性炭的孔结构对丁烷吸附性能的影响研究

对5种不同工艺制备的杉木颗粒活性炭的丁烷活性、丁烷工作容量、丁烷持附性与孔结构之间的关系进行了研究。结果表明:丁烷吸附性能与活性炭样品的比表面积、孔容积和孔径分布有着密切联系。对丁烷活性起作用的孔主要集中在1.16～2.00 nm;对丁烷工作容量有显著影响的孔径介于2.0～4.0 nm;对丁烷持附性影响最大的孔分布在0.5～1.0 nm。大孔对整个吸附过程没有什么显著影响,只是作为丁烷分子进入中孔、微孔的输送通道。     

KOH活化高比表面积椰壳活性炭的制备及其性质研究

以椰壳炭化料为原料,通过KOH活化法制备高比表面积活性炭,并探索温度、时间和活化比对活性炭吸附性能的影响.通过单因素试验发现,活化温度800℃,活化时间60 min,活化比值为5的条件下活性炭的吸附性能最优.制备出的活性炭比表面积为3 360 m2/g,总孔孔容为1.798 cm3/g,平均孔径为2.140 nm,对碘的吸附性能为2809 mg/g,对亚甲基蓝溶液的吸附性能为675mg/g.     

磷酸活化法制备纤维素基颗粒活性炭

以微晶纤维素为原料,在不添加黏结剂的条件下,采用磷酸活化法制备纤维素基颗粒活性炭。分析了捏合过程和炭活化工艺对活性炭耐磨强度、吸附性能和孔隙结构的影响。研究结果表明,炭活化温度的升高及保温时间的延长有利于颗粒活性炭强度的提高;随着浸渍比值的升高,颗粒活性炭的碘吸附值、亚甲基蓝吸附值、比表面积、总孔容积、微孔容积和中孔容积均呈不断上升的趋势;浸渍比值较小,较细微孔结构发达,浸渍比值较大,较大微孔结构发达。在较佳的工艺条件下:捏合温度150℃,浸渍比值1.25,捏合时间55 min,炭活化温度450℃和保温时间1.0 h,制得颗粒活性炭的碘吸附值、亚甲基蓝吸附值、强度、比表面积、总孔容积、微孔容积、中孔容积和平均孔径分别为896.6 mg/g、131.3 mg/g、94.69%、1 377.3 m2/g、1.083 cm3/g、0.514 cm3/g、0.569 cm3/g和3.14 nm。     

木质素/聚苯乙烯基水处理吸附材料的制备与吸附性能

木质素是重要的造纸工业副产物,可用于制备水处理用吸附剂。以木质素磺酸钠和聚苯乙烯为原料,通过Mannich反应制备了木质素/聚苯乙烯基水处理吸附材料,并研究其对染料水溶液中罗丹明B的吸附性能。结果表明:制备的吸附材料比表面积为269.77 m2/g、平均孔径21.09 nm,表面含有丰富的活性基团;该材料对罗丹明B具有良好的吸附性能,饱和吸附能力达到65.46 mg/g;准二级动力学模型和Langmuir模型与吸附过程拟合度较高,吸附主要发生在初始阶段,吸附作用主要受到化学吸附控制且属于单层吸附。     

基于I2/KI质量比的活性炭碘吸附值测试方法对比研究 ZHANG Li

选择了水蒸气活化椰壳活性炭(AC-11、AC-12、AC-13),磷酸活化粉末状活性炭(AC-21、AC-22),以及KOH活化石油焦高比表面积活性炭(AC-31、AC-32)7种以常见方法制备的,比表面积在800～3 500 m²/g范围的活性炭,研究了2种I₂/KI质量比对活性炭碘吸附值测定结果的影响,并分析了活性炭比表面积和孔隙结构对碘吸附值的影响。研究结果显示：活性炭的比表面积越大、中孔越发达、中孔分布越宽,I₂/KI质量比对活性炭碘吸附值的影响就越大,m(I₂)∶m(KI)为1∶1.5下测试样品AC-31的碘吸附值与其在m(I₂)∶m(KI)为1∶2条件下的差值能达到140 mg/g;对于碘吸附值在800 mg/g左右的微孔型活性炭AC-13,2种比例测试得到的差值几乎可以忽略不计,也就是说旧版和新版的木质和煤质活性炭标准得到的活性炭碘吸附值差别很小。在活性炭碘吸附值测试条件下,吸附碘有效孔隙主要集中在0.8～1.5 nm之间。对于椰壳活性炭等微孔型活性炭,其比表面积...     

水蒸气活化制备竹质成型活性炭及其对二硫化碳的吸附性能

竹材是重要的林业可再生资源,以竹材代替木材制备活性炭可节省大量木材。以竹粉为原料,经磷酸活化成型后进行水蒸气二次活化,在不同工艺条件下制备了高吸附性能活性炭。通过碘吸附值、亚甲基蓝吸附值、N_2吸附-脱附等温线、二硫化碳动态吸附量等对所制活性炭的性能进行表征。结果表明:在磷酸浸渍比1.2∶1、活化时间20 min、活化温度450℃,水蒸气活化温度875℃、活化时间1 h、流量3.0 m L/min条件下,制得的活性炭BET比表面积为1 264.60 m~2/g、总孔容积为1.227 cm~3/g、平均孔径为3.88 nm、碘吸附值为1 452.96 mg/g、亚甲基蓝吸附值为307.5 mg/g、强度为91.76%、得率为30.42%;在动态干燥和30%相对湿度条件下,对二硫化碳的单位质量吸附量分别为0.416和0.390 g/g。活性炭对CS2的吸附能力主要与活性炭的孔结构有关,微孔发达、平均孔径小、碘吸附值高的活性炭更有利于CS2的吸附。由于竹材表观密度相对较低,且受到竹材自身组分的限制,所制活性炭的强度低于椰壳活性炭。     

Effects of Pore Structure of Granular Activated Carbon on n-Butane Adsorption

对5种不同工艺制备的杉木颗粒活性炭的丁烷活性、丁烷工作容量、丁烷持附性与孔结构之间的关系进行了研究.结果表明:丁烷吸附性能与活性炭样品的比表面积、孔容积和孔径分布有着密切联系.对丁烷活性起作用的孔主要集中在1.16～2.00 nm;对丁烷工作容量有显著影响的孔径介于2.0～4.0 nm;对丁烷持附性影响最大的孔分布在0.5～1.0 nm.大孔对整个吸附过程没有什么显著影响,只是作为丁烷分子进入中孔、微孔的输送通道.     

Browsing Damage on Pine (Pinus sylvestris and P. contorta) by a migrating moose (Alces alces) Population in Winter: Relation to Habitat Composition and Road Barriers

In Scandinavia, moose (Alces alces L.) sometimes cause severe browsing damage to economically-important pine. Moose-vehicle accidents have spurred construction of fences along roads, and these may interfere with moose migration between summer and winter ranges, or the road alone may be a barrier. If this happens and moose build up along roads, landowners may suffer economically. Therefore, this study investigated whether roads, fences or other factors influence the use of young pine stands by moose. Eighty stands along roads in northern Sweden were evaluated in which individually-browsed branches were counted on 9972 pines. Moose browsing was not significantly related to birch (Betula pendula Roth, B. pubescens Ehrh.) density, nor did it differ between pines (Pinus contorta Douglas or P. sylvestris L.). However, increased pine density, site productivity and proximity to a highway were associated with increased browsing. Further large-scale studies are needed to understand moose habitat selection and the effects of roads.     

Effects of Root Freezing on the Physiology and Growth of Picea glauca,Picea mariana and Pinus banksiana Seedlings Under Different Soil Moisture Regimes

The root systems of 2-yr-old Picea glauca, Picea mariana and Pinus banksiana seedlings were submitted to various frost temperatures during an artificial frost to induce different levels of root damage. Frost-damaged and control seedlings were placed in a greenhouse under high and low soil moisture regimes. Seedling growth and physiology were evaluated periodically. Seedling survival was reduced when root damage reached levels of 60-80%. Root systems of all three species showed partial to total recovery by the end of the experiment. In general, root freezing damage caused reductions in seedling growth, with these reductions becoming less significant over time. Root damage had little to no effect on black spruce and jack pine seedling physiology, while white spruce CO 2 uptake decreased with increasing root damage. Shoot nitrogen content of all three species decreased slightly with increasing root damage.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Stand Structure in Pine,Spruce and Deciduous Forests: A Comparison Between Finnish and Russian Karelia

This study investigated the stand structure in pine, spruce and deciduous forests in the border district of Finland and Russia. A total of 46 mature forest stands was selected as pairs, the members of each pair being as similar as possible with respect to their forest site type, age, moisture and topography. The stands were then compared between the two countries by means of basal areas and number of stems. The proportions of dominating tree species were 2-12% lower, and correspondingly the proportions of secondary tree species higher, in Russian forests. The density of the forest stock was also higher in each forest type in Russia. The forests in the two countries differed most radically in terms of the abundance of dead trees. The amount was two to four times higher in Russian deciduous and spruce forests, and in pine forests the difference was 10-fold. The stand structures indicated that Russian coniferous stands, in particular, were more heterogeneous than intensively managed pine and spruce stands in Finland.     

Growth and Terminal Bud Formation in Picea abies Seedlings Grown with Alternating Diurnal Temperature and Different Light Qualities

The root collar diameter and the height:diameter ratio are of particular importance in container-grown seedlings where a high density in the containers may produce spindly seedlings. Temperature regimes and light quality are known to affect plant growth. The aim of this study was to identify responses in Picea abies (L.) Karst. seedlings grown with light providing different red:far-red ratios and under temperature regimes with alternating day (DT) and night temperature (NT) from negative (DT < NT) to positive (DT > NT) difference (DIF) between DT and NT. Experiments were conducted in controlled environment chambers and in a daylight phytotron. Only limited thermoperiodic responses appeared in P . abies seedlings with respect to seedling height and dry weight accumulation. The formation of terminal buds, however, was clearly delayed in seedlings grown at negative DIF. The results indicate a requirement for day extension light that is high in far-red, to prevent terminal bud formation under natural short-day conditions. An extended study should be conducted to clarify the minimum level of light intensity and the optimal light quality needed to prevent terminal bud formation under natural short-day conditions.     

CAD与建筑设计的关系

本文分析了CAD在设计中引起的正面和负面影响,并进行了系统的阐述,从而使设计者在应用中能够保持客观的态度。