热解温度对苹果枝条生物质炭理化性质及其环境效应的影响

发布时间：2018-06-20 15:53

  本文选题：生物质炭 + 活性有机碳　； 参考：《西北农林科技大学》2017年博士论文

【摘要】：生物质炭是由生物质在完全或部分缺氧的情况下经热解炭化产生的一类多孔富碳,高度芳香化,难降解,类似活性炭的物质。生物质炭因原材料及制备条件的不同,其理化性质具有较大的差异。这在一定程度上又决定了生物质炭的环境效应。近年来,虽然国内外学者就不同原材料及制备条件下生物质炭理化特性及其环境效应开展了不少的研究,但多施用在酸性土壤中,在偏碱性的石灰性土壤中相对较少;而且关于苹果枝条生物质炭的制备及其性质和应用效果的研究更少涉及。为此,本文以苹果枝条为原材料分别在300、400、500、600℃条件下热解制备生物质炭,采用扫描电镜、红外光谱、物理化学吸附仪等技术在研究其理化性质、结构差异的基础上,通过室内培养实验研究了不同温度制备的生物质炭在石灰性土壤(X土)中的矿化特征及其对土壤有机碳含量和组成、土壤团聚体形成及稳定性的影响。同时,通过模拟铜锌污染的水体和土壤,研究了生物质炭对铜锌的吸附特征及其对土壤中铜锌形态转化和生物有效性的影响。研究取得的主要结果如下:(1)热解温度对生物质的理化性质及表面结构特征有重要影响。热解温度的增加,降低了生物质炭的产率,挥发性组分,CEC,O,H,H/C,O/C,酸性官能团及总官能团的含量,而增加了其C,固定态碳,比表面积,孔隙容积及矿质元素的含量(Cu和Mn除外)。生物质炭pH和灰分随着热解温度的增加表现为先增加后降低的趋势,BC500其pH值和灰分含量最高。热稳定分析表明,高温制备的生物质炭具有较高的热稳定性。(2)不同温度制备的生物质炭输入土壤后均可显著增加土壤有机碳含量,在300~600℃的制备温度范围内,以500℃制备的生物质炭对土壤有机碳库的提升效果最为明显。生物质炭输入土壤后的矿化分解特征及其对土壤活性有机碳的影响因热解温度不同而有较大的差异。与对照相比,低温(≤400℃)制备的生物质炭在培养期间增加了土壤微生物量碳(MBC)、水溶性有机碳(WSOC)以及易氧化有机碳(ROC)的含量,且随着添加比例的增加而增加,培养360 d后,BC300处理平均分别增加了38.25%、82.09%和63.53%;BC400处理平均分别增加了26.07%、65.61%和48.09%,且差异均达到显著水平(P0.05);高温(400℃)制备的生物质炭在培养初期增加了土壤MBC、WSOC及ROC含量,且随着添加比例的增加而增加,而在培养后期则减少了土壤MBC、WSOC、ROC含量,且随着添加比例的增加而减少,培养360 d后,BC500处理平均分别减少了1.28%、13.48%和14.67%,BC600处理平均减少7.80%、14.66%和15.79%,且差异达到显著水平(P0.05)。双库模型能够很好地描述不同温度制备的生物质炭输入对土壤有机碳库及其分解速率的影响。不同温度制备的生物质炭输入土壤后土壤有机碳的半衰期变化在22.77~47.83a之间,且随着热解温度及生物质炭添加比例的增加,土壤有机碳的半衰期呈现增加的趋势。(3)随着热解温度的升高,生物质炭类腐殖物质的含量呈降低的趋势,但生物质炭类腐殖物质的结构趋向复杂化。生物质炭输入土壤后,与对照相比,低温(≤400℃)制备的生物质炭在培养期间增加了土壤胡敏酸(ha)含量,并随着添加比例的增加而增加,培养360d后,bc300和bc400处理平均分别增加了69.93%和48.75%,且差异达到显著水平(p0.05);富里酸(fa)含量在培养前期(240d)也有所增加,但后期则减少了土壤fa含量;高温(400℃)制备的生物质炭在培养过程中主要降低了土壤ha和fa含量(仅在培养初期阶段引起土壤ha、fa含量的短时间增加),培养结束时,bc500处理分别减少了34.38%和44.48%,bc600处理平均分别减少了42.84%和49.27%,且差异均达到显著水平(p0.05)。生物质炭输入显著增加了土壤胡敏素(hu)的含量,其中以bc500处理的增加效应最大。生物质炭输入增加了土壤h/f比,提高了土壤hu的相对含量,增加了土壤中相对稳定性碳的比例。高温制备(400℃)的生物质炭培养结束时显著降低了土壤ha及fa的色调系数(Δlgk),使土壤腐殖物质的结构复杂化,而低温制备的则相反。(4)生物质炭输入土壤均可以不同程度的增加0.5mm粒级土壤水稳性团聚体含量,尤其是5-8mm以及2-5mm土壤水稳性团聚体含量,且随着添加比例的这种趋势更加明显。同时,生物质炭输入增加了土壤团聚体的wr0.25,mwd以及gmd,土壤团聚体结构稳定性有所加强,且随着添加比例的增加而增加。不同制备温度间相比,bc500对土壤水稳性团聚体组成及稳定性的影响最为显著。生物质炭输入均可显著增加各粒级土壤有机碳含量,且以bc500处理下提升效果最为明显。不同粒级间相比,生物质炭输入对5-8mm以及2-5mm粒级土壤水稳性团聚体有机碳含量的增幅最大,并随着添加比例的增加而增加。同时,生物质炭输入可以改变土壤有机碳在土壤水稳性团聚体中的分配,与对照相比,四种温度制备的生物质炭输入增加了0.5mm土壤水稳性团聚体,尤其是5-8mm和2-5mm水稳性团聚体中有机碳的分配,其中bc500处理与对照相比差异均达到显著水平。(5)不同温度制备的苹果枝条生物质炭对cu(ii)和zn(ii)均具有较强的吸附能力。随着生物质炭用量的增加,生物质炭对cu(ii)和zn(ii)吸附效率明显降低,而去除效率显著增加;在ph2~6范围,随着ph值的增加,生物质炭对cu(ii)和zn(ii)的吸附量先增加而后降低,在ph为5.0时,吸附量达到最大值;生物质炭对cu(ii)和zn(ii)的吸附在6h内吸附速率较快,而后吸附速率变慢,在24h内吸附达到平衡,生物质炭对cu(ii)和zn(ii)的吸附过程符合准二级动力学模型,表明吸附过程主要受化学吸附所控制;langmuir等温吸附模型可以很好的描述生物质炭对cu(ii)和zn(ii)的吸附过程,表明生物质炭对cu(ii)和zn(ii)的吸附主要是单层吸附;生物质炭对cu(ii)和zn(ii)的吸附量随着溶液温度的增加而增加,热力学分析表明,生物质炭对cu(ii)和zn(ii)的吸附过程是一个自发的吸热过程。不同温度制备的生物质炭相比,BC500对Cu(II)和Zn(II)的吸附量在不同的条件下均为最高(除了初始pH为2.0时);而不同的离子间相比,生物质炭对Cu(II)的吸附量大于Zn(II)。(6)生物质炭输入可增加土壤有机结合态铜锌的含量,减少了土壤交换态、碳酸盐结合态以铁锰氧化物结合态铜锌的含量。其中,BC500处理下土壤有机结合态铜锌的增幅最高,培养360 d后期土壤有机结合态铜锌比对照平均分别增加了21.12%和39.26%。生物质炭输入显著降低了土壤有效铜锌的含量,而BC500处理导致土壤有效铜锌下降的幅度最大,培养360 d后,土壤有效铜锌平均比对照下降了40.58%和38.54%。有效铜锌含量的降低导致其对小白菜的毒害降低,生物质炭输入增加了小白菜地上部分及根系干重,降低了地上部分及根系铜锌浓度。四种温度制备的生物质炭相比,小白菜地上部分及根系干重表现为BC500BC400BC300BC600CK,而小白菜地上部分及根系铜锌浓度则表现为CKBC600BC300BC400BC500。生物质炭输入对土壤的pH值及有机碳含量的影响是改变土壤重金属形态分布及其有效性的重要原因。综上所述,生物质炭因热解温度不同,自身理化性质和结构存在较大的差异,其环境效应也有所不同。与其他制备温度相比,在500℃下制备的苹果枝条生物质炭,不仅可显著增加土壤稳定性有机碳的含量、土壤腐殖化程度、土壤团聚体的稳定和大团聚中有机碳的分配,同时,在此条件下制备的生物质炭还可以有效吸附水体铜锌等重金属,且对污染土壤中铜锌的钝化作用最为显著。因此,500℃是生物质炭用于重金属污染修复及提升偏碱性的石灰性土壤质量的最佳制备温度。
[Abstract]:Biomass charcoal is a kind of porous carbon rich, highly aromatic, hard to degrade and similar to activated carbon produced by pyrolysis and carbonization of biomass under the condition of complete or partial anoxia. Biomass charcoal has great differences in physical and chemical properties because of the different raw materials and preparation conditions. This determines the environment of biomass carbon to a certain extent. In recent years, many studies have been carried out on the physicochemical properties and environmental effects of biomass charcoal in different raw materials and preparation conditions, but most of them are used in acid soil and relatively less in alkaline calcareous soils; and the preparation, properties and application effects of apple branch raw carbon are also studied. In this paper, the biomass charcoal was prepared by pyrolysis of apple branches at 300400500600 degrees centigrade, using scanning electron microscope, infrared spectroscopy and physical chemical adsorption apparatus to study the physicochemical properties and structural differences of the biomass, and the biomass charcoal prepared at different temperatures was studied by indoor culture experiments. The characteristics of mineralization in gray soil (X soil) and its influence on soil organic carbon content and composition, soil aggregate formation and stability. At the same time, the adsorption characteristics of biomass carbon on copper and zinc and its influence on the transformation of copper and zinc in soil and bioavailability were studied by the simulation of copper and zinc polluted water and soil. The results are as follows: (1) the pyrolysis temperature has an important influence on the physicochemical properties and surface structure characteristics of biomass. The increase of pyrolysis temperature reduces the yield of biomass carbon, volatile components, CEC, O, H, H/C, O/C, acid functional groups and total functional groups, and increases the content of its C, fixed carbon, specific surface area, pore volume and mineral element content. (except for Cu and Mn). The biomass carbon pH and ash content increased first and then decreased with the increase of pyrolysis temperature, and the pH value and ash content of BC500 were the highest. The thermal stability analysis showed that the biomass charcoal prepared at high temperature had high thermal stability. (2) the soil organic carbon could be significantly increased after the raw material charcoal prepared at different temperatures was entered into the soil. In the range of preparation temperature at 300~600 C, biomass carbon prepared at 500 C has the most obvious effect on soil organic carbon storage. The mineralized decomposition characteristics of biomass charcoal and its influence on soil active organic carbon have great difference due to the temperature of pyrolysis. Compared with the control, low temperature (less than 400 degrees C) is prepared. The content of soil microbial biomass carbon (MBC), water soluble organic carbon (WSOC) and oxidizable organic carbon (ROC) increased during the incubation period, and increased with the increase of adding proportion. After 360 D, BC300 treatment increased by 38.25%, 82.09% and 63.53% respectively, and BC400 treatment increased by 26.07%, 65.61% and 48.09%, respectively. The high temperature (400 C) increased the content of soil MBC, WSOC and ROC in the early stage of culture, and increased with the increase of adding proportion, but decreased the content of MBC, WSOC and ROC in the later period of culture, and decreased with the increase of adding proportion, and the average of BC500 treatment decreased by 1. after the cultivation of 360 D. 28%, 13.48% and 14.67%, the average reduction of BC600 treatment was 7.80%, 14.66% and 15.79%, and the difference reached a significant level (P0.05). The dual reservoir model could well describe the effect of biomass carbon input on soil organic carbon pool and its decomposition rate. With the increase of the pyrolysis temperature and the proportion of biomass carbon, the half-life of soil organic carbon showed an increasing trend. (3) the content of biomass carbon humic substances decreased with the increase of pyrolysis temperature, but the structure of biomass carbon humic substances tended to be complex. Biomass charcoal entered the soil. (3) Compared with the control, the biomass charcoal prepared at low temperature (< 400 C) increased the soil humic acid (HA) content during the incubation period, and increased with the increase of the addition ratio. After 360D, the average increase of bc300 and bc400 was increased by 69.93% and 48.75% respectively, and the difference reached a significant level (P0.05). The content of fulvic acid (FA) was also in the early stage of culture (240d). In the later period, the soil FA content was reduced, and the biomass carbon prepared at high temperature (400 C) decreased the content of soil HA and FA in the process of culture (only in the early stage of culture, which caused the soil HA, the FA content increased in a short time). At the end of the culture, the BC500 treatment decreased by 34.38% and 44.48% respectively, and the average of bc600 treatment decreased by 42.84% respectively. And 49.27%, and the difference reached significant level (P0.05). Biomass carbon input significantly increased the content of soil humin (HU), among which the increase effect of BC500 treatment was the greatest. Biomass carbon input increased the soil h/f ratio, increased the relative content of soil Hu, increased the ratio of relative stability of soil in soil and increased the ratio of the relative stability of soil in soil. The tonal coefficient (delta LGK) of soil HA and FA was significantly reduced at the end of the material carbon culture, and the structure of soil humus was complex, while the low temperature was the opposite. (4) the content of water stable aggregates in the 0.5mm grain grade soil could be increased in different degrees, especially in 5-8mm and 2-5mm soil. In addition, with the increasing proportion of this trend, biomass carbon input increased the wr0.25, MWD and GMD of soil aggregates, and increased the stability of soil aggregates, and increased with the increase in proportion. Compared with the different preparation temperatures, the effects of BC500 on the stability of soil soil water stabilized aggregates and stability were the most. Biomass carbon input can significantly increase the content of soil organic carbon in each grain grade, and the most obvious enhancement effect under the BC500 treatment. Biomass carbon input to 5-8mm and 2-5mm grain grade soil water stable aggregate organic carbon content is the largest increase, and increase with the increase in the proportion of biomass carbon, biomass carbon, at the same time, biomass carbon. The input can change the distribution of soil organic carbon in the soil water stable aggregate. Compared with the control, the four temperature prepared biomass carbon input increased the 0.5mm soil water stable aggregate, especially the distribution of organic carbon in the 5-8mm and 2-5mm water stable aggregates, in which the difference of the BC500 treatment was significantly higher than that of the control. (5) the difference was different. The adsorption capacity of Cu (II) and Zn (II) was stronger with the temperature prepared by the biomass carbon. With the increase of biomass carbon content, the adsorption efficiency of Cu (II) and Zn (II) was obviously reduced, and the removal efficiency was significantly increased. The adsorption amount of biomass carbon to Cu (II) and II increased with the increase of pH value in the ph2~6 range. The adsorption rate reached the maximum when pH was 5. The adsorption rate of biomass carbon adsorbed on Cu (II) and Zn (II) was faster in 6h, and then the adsorption rate was slow and the adsorption reached equilibrium in 24h. The adsorption process of biomass carbon on Cu (II) and Zn (II) was in accordance with the quasi two order kinetic model, which showed that the adsorption process was mainly controlled by chemical adsorption; Langmuir was mainly controlled by chemical adsorption. The adsorption process of biomass carbon to Cu (II) and Zn (II) can be well described. It shows that the adsorption of biomass carbon to Cu (II) and Zn (II) is mainly monolayer adsorption, and the adsorption of biomass carbon to Cu (II) and Zn (II) increases with the increase of solution temperature. The adsorption of Cu (II) and Zn (II) by BC500 is the highest (except initial pH 2), while the adsorption capacity of biomass carbon to Cu (II) is greater than Zn (II). (6) biomass carbon input can increase the organic binding state of copper and zinc in soil. The content of soil exchange state is reduced, and the content of copper and zinc in the bound state of iron and manganese oxides is reduced in the carbonate bound state. Among them, the increase of copper and zinc in soil organic binding state under BC500 treatment is the highest, and the organic bound copper and zinc in the later period of 360 D is increased by 21.12% and 39.26%., respectively, and the effective copper and zinc in soil can be significantly reduced by the input of biomass carbon. BC500 treatment resulted in the largest decrease in soil effective copper and zinc. After 360 d culture, the effective copper and zinc in soil decreased by 40.58% and 38.54%. in effective copper and zinc decreased, resulting in lower toxicity of copper and zinc to Chinese cabbage. The input of biomass carbon increased the dry weight of the upper part of the Chinese cabbage and root, reduced the upper part and root of the soil. The concentration of copper and zinc. Compared with four kinds of biomass carbon, the dry weight of the upper part and root of Chinese cabbage was BC500BC400BC300BC600CK, while the concentration of copper and zinc in the upper part and root of Chinese cabbage showed that the effect of CKBC600BC300BC400BC500. biomass carbon input on the soil pH value and organic carbon content was the change of the soil heavy metal speciation. In summary, biomass charcoal has great differences in physical and chemical properties and structure because of different pyrolysis temperature, and its environmental effects are different. Compared with other preparation temperatures, the apple branch biomass carbon prepared at 500 C can not only significantly increase the content of soil stable organic carbon, but also soil decay. The degree of colonization, the stability of soil aggregates and the distribution of organic carbon in the large agglomeration, and the biomass charcoal prepared under this condition can also effectively adsorb heavy metals such as copper and zinc in water, and the passivation effect on copper and zinc in contaminated soil is the most significant. Therefore, 500 degrees centigrade is used for the remediation of heavy metal pollution and the improvement of alkaline lime by biomass carbon. The optimum preparation temperature for the quality of the soil.
【学位授予单位】：西北农林科技大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：S141
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本文编号：2044802