Effect of acid-associated mechanical pretreatment on the hydrolysis behavior of pine sawdust in subcritical water

The effects of sulfuric acid-associated mechanical pretreatment on the hydrolysis behavior of pine sawdust were investigated in this study.Sulfuric acid could act as an acidic catalyst to depolymerize holocellulose through cleavage of the glycosidic bonds,the dissociation energies of which were supplied by the impact of a ball on pine sawdust,during milling.The destruction of glycosidic and hydrogen bonds in pine sawdust resulted in a decrease of crystallinity and an increase of water solubility.The sulfuric acid could promote the hydrolysis of holocellulose and its hydrolysis products.It also destroyed the chemical linkages between holocellulose and lignin during ball milling.The cleavage of chemical linkages with holocellulose made lignin more difficult to hydrolyze in subcritical water,and higher activation energy was needed to hydrolyze pretreated pine sawdust at higher reaction temperatures.It also led to the formation of glucose char and aromatic-linked polymer char from the hydrolysis products of holocellulose.

Modelling the Suitability of Pine Sawdust for Energy Production via Biomass Steam Explosion

Biomass material as a source of fuel is difficult to handle, transport, store, and utilize in its original form. To overcome these challenges and make it suitable for energy prodution, the material must be pre-treated. Biomass steam explosion is one of the promising pretreatment methods where moisture and hemicellulose are removed in order to improve biomass storage and fuel properties. This paper is aimed to model the suitability of pine saw dust for energy production through steam explosion process. The peak property method was used to determine the kinetic parameters. The model has shown that suitable operating conditions for steam explosion process to remove moisture and hemicellulose from pine sawdust. The temperature and pressure ranges attained in the current study are 260 -317 ℃ (533 -590 K), 4.7 -10.8 MPa, respectively.

Non-Isothermal Degradation and Thermodynamic Properties of Pine Sawdust

The study of non-isothermal kinetics analyzed the reactivity of pine sawdust, while the thermodynamic properties analyzed energy consumed and released from the pine sawdust. The kinetic parameters were determined by analyzing mass loss of pine sawdust components by using Thermogravimeric analyzer. The cellulose has the highest conversion rate of 9.5%/min at 610 K compared to hemicellulose and lignin, which are 5%/min at 600 K and 2%/min at 800 K, respectively. The activation Energy for cellulose, hemicellulose and lignin was 457.644, 259.876, and 89.950 kJ/mol, respectively. The thermodynamic properties included the change of Gibbs free energy for cellulose and hemicellulose, which were -214.440 and -30.825 kJ/mol respectively, their degradation was spontaneous in forward direction, while change of Gibbs free energy for lignin was 207.507 kJ/mol, which is non-spontaneous reaction. The positive value of change of entropies for the active complex compounds formed from hemicellulose and cellulose is less stable, while the active complex compounds of lignin are characterized by a much higher degree of arrangement since its change of entropy is negative. The kinetic and thermodynamic properties show that pine sawdust is a good candidate for production of char since it is easier to remove hemicellulose through thermal process.

Gas Characteristics of Pine Sawdust Catalyzed Pyrolysis by Additives

In order to effectively investigate the variation of gas production characteristics of biomass under normal-speed pyrolysis conditions,the gas production rate,gas production component yield and gas production calorific value of pine sawdust with adding Na_(2)CO_(3),CaO and Fe_(2)O_(3)were systematically analyzed.In the experiment,an improved tube furnace was used to research the pyrolysis process with the temperature from 350℃to 750℃.The results indicate that the gas yield rises with the increase of temperature without additives,reaching 19.59%at 750℃.The liquid yield reaches 59.38%at 450℃and then the yield change is small.CaO increases the calorific value of the pyrolysis product gas due to the adsorption of CO_(2).Na_(2)CO_(3)is fused with inorganic substances in the biomass to form a char skeleton structure.The effect of Fe2O3 on H2 is more obvious at higher temperature.Na_(2)CO_(3)has the most obvious effect on the pyrolysis of pine sawdust among the discussed additives,which effectively promotes the production of H_(2).

Combustion Characteristics and Kinetics of Anthracite Blending with Pine Sawdust

The combustion characteristics and kinetics of anthracite,pine sawdust and their blends were investigated under combustion condition by thermogravimetric analysis,respectively.The fractions of pine sawdust in the blended samples were set to be 30%,50%,and 80%.The results showed that the ignition and burnout temperatures of pine sawdust were lower and the maximum combustion rate was higher than those of anthracite.With the increase of pine sawdust content,the ignition temperature and burnout temperature of the blends decreased,while the maximum mass loss rate and the combustible index of the blends increased;that is,the comprehensive combustion property became better.The kinetic parameters for the blends combustion under air condition were calculated based on experimental results using Coats-Redfern model.When the pine sawdust content varied in the range of 30%-80%,the combustion processes of these blends could be divided into two stages and the combustion reactions belong to the first-order reaction.The values of apparent activation energy at two individual stages decreased from 68.78to47.28kJ·mol-1 and from 113.53 to 46.43kJ·mol-1,respectively.

木醋液对4种蔬菜种子萌发的影响

目的:探究松木屑木醋液对蔬菜作物的化感效应,以期为松木屑木醋液合理种植蔬菜作物提供理论依据。方法:研究不同浓度木醋液对萝卜、韭菜、小白菜和芥菜种子萌发和幼苗生长的化感效应。结果:木醋液对4种蔬菜种子萌发和幼苗生长的最佳浓度及化感促进作用不同,2 000倍稀释木醋液处理下,与对照组相比萝卜种子的发芽率、发芽指数和根长及小白菜种子的根长分别提高了20.00%、22.60%、5.90%、19.50%(P <0.05);500倍稀释木醋液处理下,与对照组相比韭菜种子的发芽率和茎长分别提高了8.89%、30.60%(P <0.05);1 000倍稀释木醋液处理下,与对照组相比芥菜种子的发芽率、活力指数和茎长分别提高了8.00%、31.33%、46.70%(P <0.05)。结论:低浓度松木屑木醋液具有促进4种蔬菜作物种子生长的化感作用。

木醋液中苯酚等酚类物质的应用分析

通过乙酸乙酯萃取-旋转薄膜蒸发-丙酮萃取-旋转薄膜蒸发精制松木屑木醋液并进行气相色谱-质谱(GC-MS)分析,结果表明相对含量最高的化合物是苯酚(18.92%)。木醋液的稀释液种子萌发实验结果表明,稀释倍数为2000倍时,萝卜和菠菜的发芽率与对照组差异极显著,分别为96%和97%,而对照组的发芽率分别为82%和83%,处理组的发芽率均比对照组高;稀释倍数为100倍时,萝卜和菠菜的发芽率与对照组差异极显著,均只有3%,均比对照组低。

木醋液的化学加工利用及其功效评价

以木醋液和桑叶为原料,对木醋液和桑叶及其混合提取物的成分进行气相色谱-质谱(GC-MS)分析。研究结果表明正己烷萃取的木醋液(PWV2)共鉴定出15种化合物,其中GC含量最高的化合物为愈创木酚(35.27%)。桑叶体积分数75%乙醇冷凝回流浸提物(ME)共鉴定出2种化合物,其中GC含量最高的化合物为油酸(79.73%)。木醋液和桑叶混合物(MPWV4)的种子萌发实验结果表明萝卜和韭菜种子的发芽率显著提高,混合物中的酚酸类化合物对种子萌发具有一定的促进作用,因此在化工应用方向上具有潜在的价值。

自然对流下含水率突变锯末阴燃转明火的实验研究

多孔固体可燃物含水率不连续分布会对其阴燃过程产生影响,并可能会促进阴燃向明火转变。该文对自然对流条件下含水率突变的锯末材料阴燃转明火过程进行实验研究。实验样品前半部分保持干燥,后半部分含水率增加(干基含水率:11.83%~60.35%)。实验结果表明,当后半部分干基含水率小于19.30%时,阴燃能够自维持传播;当后半部分干基含水率在20.40%~51.69%之间时,阴燃蔓延过程中会在含水率突变处形成有利于气体积聚的空隙,并发生向明火的转变;当后半部分干基含水率大于53.57%时,不会发生转明火现象。固体内部温度和气体产物演化过程表明,含水率突变处发生阴燃转明火是高温、突变处形成的空隙和可燃气体积聚共同作用的结果。

添加松木屑对无灰煤基活性炭结构和电化学性能的影响

以褐煤基无灰煤和松木屑为原料,以KOH为活化剂,制备双电层电容器用活性炭电极材料。采用XRD,FTIR,SEM及低温N 2吸脱附表征活性炭的组成和结构,通过循环伏安测试、恒流充放电测试及交流阻抗测试考察其电化学性能。结果表明:制备时向无灰煤中添加松木屑可以改善活性炭的孔径分布,提高活性炭的电化学性能。当松木屑添加量为30%时,活性炭的电化学性能达到最佳,此时比表面积为2695 m^(2)/g,比不添加松木屑时增加了44%,且0.5 nm~1.5 nm的有效孔增加了11%,小于0.5 nm的无效孔减少了24%,孔径分布更加合理。以该活性炭作双电层电容器的电极材料,在0.05 A/g的电流密度下比电容达到321 F/g,比以不添加松木屑时制备的活性炭作电极材料时的比电容提高了30%,电荷转移电阻降低了35%,证明添加松木屑可有效改善无灰煤基活性炭的电化学性能。

生物质气化制氢耦合废旧锂离子电池正极材料回收

随着锂离子电池进入报废期,从废旧锂离子电池中回收有价金属具有重要的经济和环境意义。提出了一种生物质气化制氢与废旧锂离子电池还原焙烧回收相结合的方法。以松木屑(PS)为原料,在675℃条件下进行水蒸气气化,利用气化过程中产生的还原性气体(H_(2)、CO和CH4等)和半焦(C)对LiCoO_(2)进行原位分解还原,并使用CaO作为CO_(2)吸附剂,进一步提高气体中H_(2)的含量。结果表明,在675℃且PS与LiCoO_(2)混合质量比为1的条件下,Li和Co的回收率分别为83.4%±4%和96.5%±2%,且H2含量高达73%。本研究提供了一种绿色、环保、高效回收废旧锂电池中有价金属的有效方法。

白松木屑半焦与褐煤共气化过程中的协同效应

对白松木屑在200、300和400℃下马弗炉烘焙预处理制得半焦,与胜利褐煤进行共气化研究.傅里叶变换红外(FTIR)光谱分析表明,200和300℃制得白松木屑半焦中主要含有―C―O―、―CH3和―OH三种官能团,而400℃制得白松木屑半焦和褐煤结构相似,主要含有―C=C―、―C=O和―OH三种官能团,因此,随着预处理温度升高,生物质半焦中的官能团从单键转换成双键.然后通过热重分析仪和固定床反应器对所制得的松木屑半焦、褐煤单独气化以及它们的共气化进行比较,两者的实验结果相吻合.随着制备松木屑半焦的温度升高,生物质半焦单独气化的产气率也不断提高;200和400℃制得的松木屑半焦与褐煤共气化时具有协同作用,而且400℃半焦与褐煤共气化的产气率、碳转化率和协同效率均大于200℃半焦的;300℃半焦与褐煤共气化不存在协同作用,相反,它们之间存在抑制作用.结合热重分析和固定床实验,推断协同气化主要是热解阶段松木屑半焦中碱金属和氢原子作用的结果.

松木屑在[bmim]Cl离子液体中的溶解性能

考查了松木屑在1-丁基-3-甲基咪唑氯盐([bmim]Cl)离子液体中的溶解特性。结果表明,在实验范围内,松木屑在[bmim]Cl中的溶解程度随着溶解时间的延长而增大,溶解率高达17.86%,但溶解时间超过42 h溶液颜色加深。由于木材的生理结构特性,离子液体对其不同成分的溶解过程有所区别。综纤维素在样品未溶部分中的质量分数高于溶解部分,且随着样品溶解时间的延长,在未溶部分中的综纤维素含量会升高。通过FT-IR、SEM对溶解前后的松木屑结构进行了表征,表明在溶解过程中离子液体未对松木屑各组分结构造成影响。

改性生物炭对镉离子吸附性能研究

以废弃松木屑为原料采用热分解法制备生物炭,并以氨气、硝酸、硫化钠和溴水4种化学试剂分别对其进行表面改性。采用BET、FTIR和Bohem滴定等技术对改性前后的生物炭进行表征,研究溶液pH值、初始溶液Cd2+浓度、吸附时间等因素对Cd2+吸附特性的影响,并探讨改性生物炭的吸附机理。结果表明,改性生物炭具有较大的比表面积、发达的孔结构和多种表面官能团;在一定范围内,随溶液pH值的增大、Cd2+浓度的升高、吸附时间的延长,改性生物炭对Cd2+的去除率逐渐提高,其中氨气改性生物炭对Cd2+的吸附效果最优,在溶液pH值为6、初始溶液Cd2+浓度为50mg/L、生物炭加入量为2g/L、吸附时间为6h时,氨气改性生物炭对Cd2+的吸附容量可达12.3mg/g;拟二级动力学方程和等温吸附模型均能较好地描述改性生物炭对Cd2+的吸附过程,其中氨气改性生物炭的Langmuir与Freundlich吸附常数最大。

生物炭对铅离子的吸附性能

以废弃松木屑为原料,采用控制热分解法制备了生物炭。运用BET和FTIR等技术对生物炭进行了表征,考察了生物炭对铅离子的吸附效果,并探讨了吸附机理。表征结果显示,700℃氨气处理的生物炭,其比表面积和总孔体积显著增大。实验结果表明：生物炭对铅离子的吸附效果优于普通活性炭,且以700℃氨气处理的生物炭为最佳;随溶液pH的升高生物炭对铅离子的去除率增大,当pH为4-6时去除效果较好;在溶液pH为6、初始铅离子质量浓度为50 mg/L、吸附剂加入量为1 g/L、吸附时间为6 h的条件下,700℃氨气处理的生物炭对铅离子的去除率达99%以上;700℃氨气处理的生物炭的Langmuir吸附常数和Freundlich吸附常数远大于普通活性炭和其他工艺的生物炭;铅离子在生物炭上的吸附过程符合拟二级动力学方程。

褐煤与生物质共热解特性实验研究

以松木屑和未经干燥的褐煤为原料,在管式炉中进行了两者单独热解及共热解实验.单独热解实验结果表明,随着热解温度的升高,木屑和褐煤热解的气体产率逐渐增加,而液体和固体产率逐渐减少,高温有利于煤中水分的快速蒸发,促进煤热解中间产物与水蒸气的蒸汽重整反应;共热解实验结果表明,松木屑的添加可以调配混合物的n(C)∶n(H),促进褐煤热解;松木屑掺混比例为30%时,碳转化率和产气率的实验值与计算值的差值均达到最大值,说明该条件下两者的协同作用最明显.

松木屑催化热解及热解油分析

以松木屑为原料,选取无水Na2CO3、无水Al2O3、凹凸棒土、ZSM-5共4类催化剂,利用管式炉实验及色质联用(GC-MS)分析仪进行热解特性研究,探索了热解产物产率和组分特性的变化规律.实验结果表明,松木屑在热解温度为550,℃时,产油率达到最大值51.47%(质量分数);无催化剂条件下松木屑热解油主要成分为酸类化合物,加催化剂条件下松木屑热解油主要成分为酸类和酮类化合物,催化剂的加入主要影响了呋喃类、醇类、糖类和含氮类化合物的质量分数.ZSM-5催化剂的催化性能最佳,其能够提高热解油产率,其对应的热解油中酯类、呋喃类和芳香族类等能够提高热解油品质的化合物质量分数均较高,而糖类、含氮类等化合物质量分数较低,能够提高热解油的稳定性.

松木屑木醋液对舞毒蛾幼虫的毒杀活性

分别通过浸叶法、喷雾法的室内生物测定实验研究松木屑木醋液对舞毒蛾幼虫的毒杀活性。浸叶法的室内生物测定实验结果表明,松木屑木醋液防治舞毒蛾幼虫最佳时期为1-2龄。松木屑木醋液处理舞毒蛾2龄幼虫72 h校正死亡率63.33%（超过半数致死率）。松木屑木醋液对舞毒蛾2龄幼虫喷雾法的室内生物测定实验研究结果表明,24 h松木屑木醋液对舞毒蛾2龄幼虫的半数致死浓度LC50为17.17%。通过浸叶法的室内生物测定实验研究松木屑活性炭法精制木醋液对舞毒蛾2龄幼虫的毒杀活性,结果表明第7天体积分数100%处理组的校正死亡率56.67%（超过半数致死率）。对木醋液而言,喷雾法的毒杀活性起效快。

松木屑与煤加压热解特性

研究松木屑和新疆博斯坦煤的加压单独热解及共热解特性,热解实验在加压热重分析仪上开展,压力为0.1~2.0MPa.通过样品热解失重情况绘制热解失重曲线,对曲线进行失重速率分析和热解动力学分析.结果发现,热解压力升高会抑制样品热解挥发分的析出,使样品主要热解阶段的表观活化能增大56%~85%;松木屑与煤共热解过程不是两者单独热解过程的简单叠加,而是两者协同反应相互促进或抑制的结果,松木屑与煤共热解失重相较计算值在加压条件下提高了8%~23%,在常压条件下降低了6.7%,但不管是常压还是加压共热解,共热解主要热解阶段的表观活化能均较松木屑和煤单独热解降低.

松木粉热解和生物油精制的实验研究

选用60~100目的松木粉在流化床上进行快速热解实验，在反应温度550℃及载气流量3m^3／h的条件下，热解产物中油相18．7％，水相15．9％，焦炭46．2％，气相19．2％（质量分数）。对生物油进行理化特性及元素分析，利用气相色谱-质谱联用仪对生物油成分进行定性分析。将收集的生物油进行催化裂化改质，改质生物油收率为42．81％，其中轻质芳香烃（苯、甲苯、二甲苯、萘）含量达61．13％。