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1.
以含有单一的U(VI)、Pb(Ⅱ)溶液以及U(VI)和Pb(Ⅱ)混合溶液为吸附质,系统探讨了pH值、吸附剂量、吸附时间和初始离子浓度对向日葵秸秆吸附效果的影响。采用准一级动力学方程、准二级动力学方程、粒内扩散模型、Langmuir和Freundlich等温吸附方程对实验数据进行拟合,从分配系数和分离因子角度对吸附选择性进行分析,并对吸附机理进行探讨。结果表明:吸附20 mg/L的U(VI)-Pb(Ⅱ)溶液的最佳pH值为4.0、吸附剂量为2.0 g/L、吸附时间为720 min,U(VI)和Pb(Ⅱ)的去除率分别为77.55%、87.44%;U(VI)和Pb(Ⅱ)的吸附动力学在单离子和复配体系下均符合准二级动力学模型;吸附等温线均符合Langmuir等温吸附模型,单离子最大吸附量分别为327.0和67.59 mg/g,且当U(VI)高于200 mg/L时Pb(Ⅱ)的吸附过程也能用Freundlich模型描述。当离子初始浓度较低时向日葵秸秆对Pb(Ⅱ)具有更高的吸附选择性,而较高时则相反。向日葵秸秆吸附前后的SEM、EDX和FT-IR图谱表明,吸附U(VI)和Pb(Ⅱ)的主要方式为络合和离子交换。 相似文献
2.
《林业工程学报》2019,(6)
木屑是一种常见的农林废弃物,来源广泛、价格低廉。木屑作为一种天然的生物质材料对水中的重金属离子有一定的吸附能力,但吸附效率较低。为提高木屑的吸附效率,实现农林废弃物的资源化利用,以铁杉木屑、2-氨基对苯二甲酸(2-ATP)、2-巯基丙酸(2-MPA)为原料,制备2-氨基对苯二甲酸改性铁杉木屑(AmS)和2-巯基丙酸改性铁杉木屑(MmS)两种酯化改性的新型吸附剂,并研究它们对溶液中Hg~(2+)的吸附性能。考察Hg~(2+)初始浓度、溶液p H、干扰离子以及吸附时间等对吸附性能的影响,结果表明:两种吸附剂在pH 4～8时具有较高的吸附性能,在pH 5时,AmS和MmS吸附剂的最佳吸附效率分别为93.3%和95.5%;当溶液中存在0.2 mol/L的干扰离子Ca~(2+)时,AmS和MmS吸附剂的吸附效率仍能维持在70.4%和73.4%;吸附剂的动态吸附行为均符合伪二级动力学模型,速率控制步骤为化学吸附过程,能够在60 min内快速到达吸附平衡;吸附剂的等温吸附曲线均符合Langmuir模型,为单分子层吸附。吸附试验表明,298 K时AmS和MmS吸附剂对Hg~(2+)的最大吸附容量分别为121.8和149.1 mg/g,远高于改性前的铁杉木屑(5.6 mg/g),具有良好的应用前景。 相似文献
3.
改性木屑对碱性染料吸附性能的初步研究 总被引：5，自引：0，他引：5
木屑经过改性处理,可作为一种新型吸附剂用于印染废水的脱色处理。该试验以桃木木屑为原料，经环氧氯丙烷交联，通过正交试验，测定了其对碱性品红和孔雀石绿的吸附性能，并确定了制备改性木屑的最适宜工艺条件以及吸附碱性品红和孔雀石绿的最佳条件，对扩展木材加工剩余物利用途径、以废治废具有实际意义。 相似文献
4.
以麦草碱木质素为原料通过Mannich和磺化反应合成了二甲基-正丁基-磺化木质素基氯化铵(DBSLAC)两性表面活性剂,表征了其结构,考察其在不同pH值溶液中溶解性,并以铜离子为模拟废水考察了其吸附性能,以酸性黑(ATT)和亚甲基蓝为模拟染料废水考察了其絮凝性能。结果表明:傅里叶红外光谱(FT-IR)证明产物中含有季铵根和磺酸根的化学结构,DBSLAC含氮量2.34%。DBSLAC两性表面活性剂对Cu2+的吸附平衡符合Freundlich等温方程,并且在20 mL Cu2+溶液的初始质量浓度为100 mg/L,投加量0.002 g、pH值5.5和吸附时间2 h的条件下对Cu2+的吸附效果最佳,吸附量达262.34 mg/g;在20 mL染料溶液中,对酸性黑ATT(阴离子染料)的絮凝效果在投加量0.03 g、pH值2和染料质量浓度为0.1 g/L时最佳,最大脱色率75.41%;对亚甲基蓝(阳离子染料)的絮凝效果在投加量0.3 g、pH值9和染料质量浓度为0.1 g/L时最佳,最大脱色率97.87%,结果表明DBSLAC可用作重金属离子吸附剂和染料絮凝剂。 相似文献
5.
以甲基丙烯酸(MAA)、丙烯酰胺(AM)和烯丙基磺酸钠(SAS)同时对壳聚糖进行接枝改性,合成了一系列对水溶液中的二价铜离子具有高效吸附性能的壳聚糖水凝胶。研究了吸附剂粒径、投料量、溶液pH值对吸附容量的影响,同时进行了对金属铜离子的吸附性能研究。结果显示,粒径0.074~0.2 mm的吸附剂,在25 mL铜离子(II)质量浓度4 000 mg/L,pH值6的硝酸铜溶液中,投入量为0.1 g时,壳聚糖复合水凝胶最大吸附量为823 mg/g,同时吸附容量随溶液pH值增加而增加,随投料量的增大而减小。吸附等温线研究表明,Freundlich吸附模型能更好地描述吸附剂对铜离子(II)的吸附行为,说明其吸附过程是不均匀的多分子层吸附过程。 相似文献
6.
《林产化学与工业》2018,(4)
以废弃黑曲霉菌丝体、壳聚糖为原料,用环氧氯丙烷进行交联,三聚磷酸钠进行固化,制备成黑曲霉菌丝体-壳聚糖,以此作为吸附剂对Cu~(2+)进行吸附研究,考察了吸附时间、pH值、温度、Cu~(2+)的初始质量浓度以及复合型吸附剂的投加量对吸附效率的影响,探讨了吸附的动力学和热力学规律。结果显示:提高吸附温度、吸附时间以及pH值均能使吸附率升高;在黑曲霉菌丝体-壳聚糖复合型吸附剂0.4 g,吸附时间180 min、pH值6、吸附温度为50℃、Cu~(2+)质量浓度为20 mg/L的条件下,对Cu~(2+)的吸附率达到99.42%。动力学数据分析表明吸附剂对Cu~(2+)的吸附过程符合准二级动力学模型,以化学吸附为主,粒子内扩散不是唯一的吸附速率控制步骤;吸附过程符合Freundlich等温线模型,说明吸附Cu~(2+)为非均相体系的表面吸附;ΔG0,ΔH和ΔS分别为6.104 2 kJ/mol和45.258 1 J/(mol·K),即该吸附是一个自发进行的吸热过程。 相似文献
7.
8.
研究了胶原纤维固化杨梅单宁(IBT)这一新型吸附材料对Mo6 的吸附特性.实验表明,温度对吸附容量影响不大,而pH值对吸附容量有显著影响,Mo6 的吸附容量随pH值降低而增加,表明其吸附机理是吸附剂与聚钼阴离子之间的静电结合.当Mo6 的初始质量浓度为100.0mg/L、吸附剂用量0.100 g、温度为303 K、pH值2.0时,IBT对Mo6 的吸附量为82.4 mg/g.Freundlich方程可以很好地描述IBT对Mo6 的吸附等温线.动力学研究表明,初始吸附速率很快,吸附达到平衡的时间约为600 min,其吸附动力学可很好地用拟二级速率方程描述,计算所得的平衡吸附量与实测值误差很小.解吸实验表明,0.02 mol/L EDTA溶液能使吸附剂再生,并能循环使用.选择性吸附研究表明,在酸性(pH值2.0)条件下,IBT对Mo6 的吸附率大于95%,而对Ni2 和Cu2 的吸附率低于5%,可用于Mo6 -Ni2 和Mo6 -Cu2 二元混合溶液中Mo6 的分离和提取. 相似文献
9.
KOH微波活化法处理竹炭的研究 总被引：3，自引：0，他引：3
研究了以自制的快速裂解产物竹炭为原料,采用KOH-微波辐射活化法制备竹质活性炭.利用正交试验探讨了不同因素对竹质活性炭性质的影响.最佳工艺条件为KOH质量分数 25 %,浸渍时间 24 h,微波功率 800 W,活化时间 7 min,所制备的活性炭产品的碘吸附值为 1 239.08 mg/g,亚甲基蓝吸附值为 274.95 mg/g,比表面积为 1 394.16 m2/g,亚甲基蓝吸附值为国家一级品标准(GB/T 13803.2-1999)的2.04倍,同时测定了活化前后竹炭的红外光谱.结果表明,活化后竹炭表面结构有了较大的修饰,增加了较多的表面化学官能团,从而提高了竹炭的比表面积和吸附性能. 相似文献
10.
以天然沸石和蛭石为吸附剂,采用等温吸附方法,研究其对Cu2+的吸附性能.结果表明,天然沸石对Cu2+的去除率略高于蛭石.天然沸石和蛭石的吸附容量p值分别为8.85 mg/g和6.99 mg/g.在实际应用中,天然沸石的单价低,吸附容量大,单位处理成本低,因此,天然沸石是人工湿地吸附缓冲单元理想的介质填料. 相似文献
11.
《Scandinavian Journal of Forest Research》2012,27(5):427-435
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. 相似文献
12.
《Scandinavian Journal of Forest Research》2012,27(3):206-217
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. 相似文献
13.
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. 相似文献
14.
《Scandinavian Journal of Forest Research》2012,27(2):118-130
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. 相似文献
15.
Steven Maranz Amadou Niang Antoine Kalinganire Djeneba Konaté Bocary Kaya 《Agroforestry Systems》2008,72(3):231-239
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. 相似文献
16.
《Wood material science & engineering》2013,8(2):76-84
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. 相似文献
17.
《Scandinavian Journal of Forest Research》2012,27(1):53-61
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. 相似文献
18.
《Scandinavian Journal of Forest Research》2012,27(1):15-27
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. 相似文献
19.
Astra Zaluma Lauma Bruna Darta Klavina Natalija Burnevica Kristine Kenigsvalde Andis Lazdins Talis Gaitnieks 《Forest Pathology》2019,49(6)
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. 相似文献
20.
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。 相似文献