【作者】 张春燕；

【导师】 何春霞；

【作者基本信息】 南京农业大学 ， 农业机械化工程， 2018， 博士

【摘要】 我国是农业大国,每年都产生大量的秸秆、谷壳及果皮等植物质类农业废弃物,虽然通过功能材料、直接还田、用作动物饲料或燃料等方式拓展了其利用空间和途径,然而还是有大量的农作物秸秆、果皮等植物质类农业有机废弃物被就地焚烧或堆砌于田间路旁。所以,秸秆、谷壳和果皮等量大面广的植物质类农业废弃物的资源化利用依旧是目前备受关注的问题。本研究利用秸秆生物炭、谷壳生物炭及果皮生物炭进行理化性能对比分析,采用盆栽不同作物方式试验,探讨低温段生物炭热裂解及制作工艺、不同原料制备的生物炭对作物生长及其土壤总有机碳(TOC)、总氮(TN)、磷(P)、钾(K)等元素含量的影响。以期在理论上探讨原料类型对生物炭及对应土壤的性能及主要元素含量的影响,在实践上对秸秆、谷壳和果皮等植物质类农业废弃物的高效资源化利用及作物生长、土壤改良等具有一定的实践意义。主要研究结果如下:第一部分主要分析原料的理化性能和热解制备生物炭工艺参数优化选择,主要研究结果包括以下两个方面:(1)傅立叶红外变换(FTIR)光谱和X射线衍射(XRD)图谱的试验分析发现玉米秸秆(MS)、麦秸秆(WS)、葵秸秆(SS)、葵籽壳(SH)、稻壳(RH)、栗子壳(CS)和橙皮(OS)等原料的官能团、微晶结构等相似,主要有木质素、纤维素和半纤维素等组成,具有较高的挥发分,其TG曲线随着热解温度的升高而下降,其下降主要出现在250～400℃区间,且在250～400℃区间DTG曲线有一个明显的峰值出现,而峰值大小不同,高温区间有拖尾现象,说明原料中的半纤维素和纤维素在这个温度区间基本热解完毕,400℃之后的失重主要是剩余木质素的热解与生物炭的进一步芳香化,因此,玉米秸秆(MS)、麦秸秆(WS)、葵秸秆(SS)、葵籽壳(SH)、稻壳(RH)、栗子壳(CS)和橙皮(OS)等原料的热解工艺参数和机理相同;(2)密封限氧环境代替氮气氛围限氧环境在300～700℃范围内制备生物炭的方法是可行的,且在热解温度低于500℃的低温段,密封限氧环境较氮气氛围限氧环境的热解停留时间更短,其经试验拟合方法建立的热解温度T和热解停留时间t的关系模型分别为t=-4.80973+254.94279×0.99485T和t=-65.4627+295.4227 × 0.9978T。第二部分主要测定分析了生物炭的理化性能及吸附性能,并优选出综合性能优良的生物炭作为作物盆栽试验备用试样,主要研究结果包括以下两个方面:(1)生物炭的pH值、表观密度、视孔隙率、TOC含量等随着热解温度的升高而增加,而当热解温度高于500℃时,生物炭的TN、P、K含量、炭产率及持水能力等随着热解温度的增加而减少,但不明显,通过傅立叶红外变换光谱、X射线衍射图谱和扫描电镜试验数据可以看出热解温度的升高使生物炭孔隙数量增加,芳香化程度增强。而不同原料制备的生物炭之间理化性质差异较为显著,例如果壳类生物炭的TOC、TN含量总体高于秸秆类生物炭和谷壳类生物炭,而玉米秸秆(MS)、麦秸秆(WS)、葵秸秆(SS)等农作物秸秆类生物炭的K含量远远高于葵籽壳(SH)、稻壳(RH)、栗子壳(CS)和橙皮(OS)等果壳、谷壳类生物炭。结果发现,热解温度和原料类型均对生物炭的理化性质产生影响,但是,原料类型对生物炭理化性质的影响较热解温度更为明显;(2)麦秸秆生物炭(BWS)、玉米秸秆生物炭(BMS)、葵秸秆生物炭(BSS)、稻壳生物炭(BRH)、葵籽壳生物炭(BSH)、栗子壳生物炭(BCS)和橙皮生物炭(BOS)等七种生物炭对Pb2+的吸附可同时用Frendlich和Langmuir两种模型拟合,其吸附量均较高,秸秆类生物炭(BMS、BSS和BWS)和橙皮生物炭(BOS)吸附效果较BRH、BSH和BCS谷壳、坚果壳类生物炭更好。其主要可能原因是橙皮生物炭(BOS)、葵籽壳生物炭(BSH)、稻壳生物炭(BRH)、葵秸秆生物炭(BSS)、栗子壳生物炭(BCS)、玉米秸秆生物炭(BMS)和麦秸秆生物炭(BWS)等七种生物炭对Pb2+的吸附行为受其本身的矿物组分、化学官能团、孔径孔容及比表面积等多方面影响的结果。而玉米秸秆生物炭(BMS)、葵秸秆生物炭(BSS)和麦秸秆生物炭(BWS)对亚甲基蓝溶液的吸附率远远高于橙皮生物炭(BOS)、葵籽壳生物炭(BSH)、稻壳生物炭(BRH)和栗子壳生物炭(BCS)的主要原因是其比表面积与孔结构较高导致的。第三部分将生物炭施入土壤进行作物栽培试验,分析生物炭施加对土壤中TOC等营养元素含量及作物产量等生长状况的影响,主要研究结果包括以下四个方面:(1)生物炭的施入能够显著促进作物的生长,提高作物的产量,但是生物炭的类型使其生长和产量的增加程度具有较大差异。麦秸秆生物炭(BWS)、玉米秸秆生物炭(BMS)和栗子壳生物炭(BCS)对含羞草、绿豆、小麦和红油菜苔四种作物的生长状况影响较为明显,例如,麦秸秆生物炭(BWS)、栗子壳生物炭(BCS)与玉米秸秆生物炭(BMS)的盆栽的花朵数分别较未添加组增加了 69.4%、69.9%和66.2%,产生这种现象的原因可能与麦秸秆生物炭(BWS)、玉米秸秆生物炭(BMS)的K、P等含量、孔隙率和持水能力较高等有关,而栗子壳生物炭(BCS)的TOC、TN含量高,表观密度大等性能使其对作物生长具有较佳的促进作用。(2)土壤中的TOC、TN、P和K的含量因生物炭的施入而增加,但是,其增加程度受生物炭制备原料的类型影响显著,且与生物炭中本身的TOC、TN、P和K含量大小不呈现正相关。例如,橙皮生物炭(BOS)的TOC含量最高为63.79%,但添加橙皮生物炭(BOS)的土壤的TOC含量为2.84%,而添加TOC含量仅为44.17%的稻壳生物炭(BRH)的土壤中,其TOC含量高达3.91%。(3)生物炭对土壤中的TOC、TN、P和K的含量的大小的影响与生物炭持水能力、表观密度和孔隙率等具有一定的关系,土壤中K、P元素的含量随着生物炭持水能力和视孔隙率的增加而增加,而栗子壳等果壳类生物炭因其较高的表观密度增加了土壤的通气性而使其TOC与TN的含量高于添加玉米秸秆等农作物秸秆类生物炭的土壤。(4)生物炭的施加促进了作物生长,TOC、TN、P和K的等营养元素的含量。但是,通过Origin软件对数据拟合进一步分析可知生物炭中的TOC、TN、P和K的等营养元素的含量与土壤中对应的营养元素含量及土壤中TOC、TN、P和K的等营养元素的含量之间具有一定的线性相关性,但是,土壤中的TOC、TN、P和K的等营养元素的含量与作物株高、产量不具有线性相关性,这主要可能原因是与TOC、TN、P和K的等营养元素在土壤中的迁移转化机理有关。综上所述,将玉米秸秆(MS)、麦秸秆(WS)、葵秸秆(SS)、葵籽壳(SH)、稻壳(RH)、栗子壳(CS)和橙皮(OS)等植物质类农业废弃物原料在低温密封限氧环境下热解制备富含TOC、TN、P、K等营养元素的生物炭是可行的,将其施入土壤可使作物的株高、产量等增加,促进作物生长,而且,生物炭的施加使土壤的TOC、TN、P、K等营养物质或成分的含量增加,且生物炭较高的表观密度、视孔隙率和持水能力等性能增加了土壤的透气性和养分的保持能力,有助于作物营养物质和水分等的供应,促进作物的生长,提高作物的产量。而其pH值与试验土壤的pH值相近,不会对土壤的酸碱性产生影响。更多还原

【Abstract】 There are large amounts of waste such as straw,husks and peels result from large agricultural country in China.Although plenty of them has been used as functional materials,direct return to land,animal feed,or fuel,et al.there is still good deal of them has been burned or discarded in field or roads.Therefore,the development use of plant-quality agricultural wastes,such as straw,husks and peels is getting an increasing attention nowadays.In this paper,pot experiments with different crops were carried out to determine the effects of biochar prepared from different raw materials on crop growth and content of TOC,TN,P,K,and other elements.The paper was aimed to assess the effects of raw material types on biochar and its corresponding soil properties and the content of major elements.The results were showed as following:The first part mainly analyzed the physical and chemical properties of raw materials and the optimization of biochar process parameters for pyrolysis preparation.The main research results included the following two aspects:(1)The results of fourier transform infrared(FTIR)spectroscopy and X-ray diffraction(XRD)patterns showed that the functional groups and microcrystalline structures of MS,WS,SS,SH,RH,CS and OS were similar.The TG curves of corn stalk(MS),wheat straw(WS),sunflower straw(SS),sunflower seed husk(SH),rice husk(RH),chestnut shell(CS)and orange peel(OS)decreased with temperature,and the decline was mainly in the range of 250-400℃.And there was a distinct peak of DTG curves in the range of 250～400℃ and tailing phenomenon in the high temperature range,which indicated that the hemicellulose and cellulose in the raw materials were basically pyrolyzed at this temperature range,and the weight loss after 400℃ is mainly the pyrolysis of the remaining lignin and the further aromatization of the biochar.Thus,the pyrolysis process of MS,WS,SS,SH,RH,CS and OS had the same parameters and mechanism.(2)The preparation of biochar with sealed method instead of N2 atmosphere in the range of 300-700℃ was proved to be feasible.And compared to condition in nitrogen atmosphere,the residence time was shorter under sealing oxygen limiting method when the temperature was below 500℃.Meanwhile,the relationship between the pyrolysis temperature(T)and the residence time(t)with sealed method and N2 atmosphere were established by experimental fitting as follows:t=-4.80973+254.94279×0.99485T and t=-65.4627+295.4227×0.9978T respectively.The second part mainly analyzed the physical and chemical properties and adsorption properties of biochar,and optimized the biochar with excellent comprehensive performance as a spare sample for crop pot experiment.The main research results included the following two aspects:(1)The pH,apparent density,porosity and TOC content of biochar increased with pyrolysis temperature.However,the yield,the TN,P,K content of biochar,and water holding capacity decreased slightly with pyrolysis temperature when the pyrolysis temperature was higher than 500℃.The results of fourier transform infrared(FTIR),X-ray diffraction(XRD)and scanning electron microscopy(SEM)showed that the pore volume of biochar and the degree of aromatization increased with pyrolysis temperature.The results showed that the pyrolysis temperature and the type of raw materials all had an impact on the physicochemical properties of biochar.However,the influence of raw material types on the physicochemical properties of biochar was more pronounced than the pyrolysis temperature.(2)The adsorption of Pb2+by biaochrs of wheat straw(BWS),maize straw(BMS),sunflower straw(BSS),rice husk(BRH),sunflower husk(BSH),chestnut shell(BCS)and orange skin(BOS)could be fitted by both Frendlich and Langmuir models.The adsorption of Pb2+by seven biochars of BMS,BSS,BWS,BRH,BSH,BCS and BOS can be fitted by both Frendlich and Langmuir models,and the adsorption amount is high.Meanwhile,biochars of straw(BMS,BSS and BWS)and orange peel(BOS)adsorption effect was better than BRH,BSH and BCS chaff,nut shell biochar.The main possible reasons were that the adsorption behavior of Pb2+ by seven biochars BOS,BSH,BRH,BSS,BCS,BMS,BWS was affected by its own mineral components,chemical functional groups,pore volume and specific surface area.Meanwhile,the higher specific surface area and pore structure were the main reason of that the adsorption rate of biochars of maize straw(BMS),sunflower straw(BSS)and wheat straw(BWS)on methylene blue solution was much higher than that of orange shell(BOS)and sunflower seed shell(BSH).In the third part,biochar was applied to the soil for crop cultivation experiment,and the effects of biochar application on the growth of TOC and other nutrients in the soil and crop yield were analyzed.The main research results included the following four aspects:(1)The crops pot experiments showed that the growth of crops was promoted and the yield of crops was increased because of biochar added.Particularly,the type of biochar had great differently effect on the growth and yield of crops.For example,compared to the non-addition group,the number of potted flowers of BWS,BCS,and BMS group increased by 69.4%,69.9%,and 66.2%,respectively.Probably,the effects of BWS,BMS and BCS on the growth status of mimosa,mung bean,wheat and red canola were more obvious compared with others,which was mainly because the much content of K,P,porosity and better water holding capacity of BWS and BMS,as well as TOC and TN content and high apparent density of BCS made it better for the growth of crops.(2)The contents of TOC,TN,P,and K in soil increased with the application of biochar.However,the increased amount was significantly affected by the type of raw material for biochar preparation but had no positive correlation with the content of TOC,TN,P and K in the biochar itself.For example,the TOC content of BOS was as high as 63.79%,but the TOC content of soil with BOS was only 2.84%,while the TOC content in the soil was as high as 3.91%for 44.17%of TOC content in BRH.(3)The effect of biochar on the contents of TOC,TN,P,and K in soil had a certain relationship with the biochar water holding capacity,apparent density and porosity,and the contents of K and P in the soil vary.The content of K and P in soil increased with the increase of water holding capacity and apparent porosity of biochar.The soil with BCS had higher TOC and TN content than other soils probably was mainly because that high apparent density increased aeration of soil.(4)The growth of crops and the content of nutrients such as TOC,TN,P,and K were promoted with the application of biochar.However,further analysis of data fitting by Origin software showed that the contents of nutrients such as TOC,TN,P,and K in biochar and the corresponding nutrient elements in soil and the nutrients such as TOC,TN,P,and K in soil There is a linear correlation between the contents of elements,but the content of TOC,TN,P,K and other nutrients in the soil is not linearly related to the plant height and yield.This may be due to TOC.The transfer mechanism of nutrients such as IN,P and K in soil is related to the mechanism of migration and transformation.In summary,the straw is rich in TOC,TN,P,K and other elements,can provide or increase the content of TOC,N,P,K and other nutrients or components for soil and crops,and the apparent density of biochar is high.Depending on the properties such as porosity and water holding capacity,the permeability of the soil and the ability to maintain nutrients are increased,which contributes to the supply of crop nutrients and moisture,promotes the growth of crops,and increases the yield of crops.The pH value of the test soil is similar to that of the test soil and does not affect the acidity and alkalinity of the soil.更多还原