Treated Tropical Wood Sawdust-Polypropylene Polymer Composite: Mechanical and Morphological Study

In this research, composites based on treated tropical sawdust and polypropylene (PP) were prepared using hot press molding machine. Raw sawdust was chemically treated with monomer, 2 - ethylhexyl methacrylate in order to improve the mechanical properties of the composites. The influence of the chemically treated sawdust on the physical and mechanical properties of sawdust-PP composites were investigated at various loading level from 10 wt.% up to 30 wt.%. Results indicate that the mechanical properties of the chemically treated sawdust–PP composites were found to be higher than those of the raw ones respectively. The surface morphology obtained from scanning electron microscopy (SEM) showed that raw sawdust–PP composites possess surface roughness and weak interfacial adhesion between the matrix and the filler while the chemically treated one showed improved filler–matrix interaction. This indicates that better dispersion of the filler with the PP matrix has occurred upon chemical treatment of the filler. Water absorption tests showed that composites prepared from the chemically treated sawdust absorb lower amount of water compared to the ones prepared from raw sawdust, suggesting that hydrophilic nature of the cellulose in the sawdust has significantly decreased upon chemical treatment.

Physicochemical and Thermal Properties of Some Key Tropical Sawdust Woods for Energy Production

In South Saharan countries, 85% of the population uses biomass as a primary energy source. Cameroon presents one of the highest biomass energy and sawmills produce important sawdust resources which are not used and are burnt in piles leading to significant air toxic emissions. Therefore, we have to valorize industrially these available sawdusts. This study focuses on the physicochemical and thermochemical analysis of Ayous, Sapelli and Tali sawdust. The proximate and ultimate analysis, particle size, structural composition, as well as heavy metal content and calorific value were determined. In addition, the thermogravimetric mass losses were also estimated. The results showed that high water contents (24% - 41%) were recorded in the raw sawdust, and the thermal treatment reduced these contents from 78% to values in the range of 4% - 9%. The values for ash and volatile matter content were respectively between 0.25% - 0.74% and 68% - 76%. The LHV is higher in Ayous (17.5 MJ/kg) and Sapelli (16.8 MJ/kg) than that of Tali (15.7 MJ/kg). The concentration of heavy metals is very low in each species. Extractives are more present in Tali (16.06%) than in the other sawdusts. Pyrolysis of sawdust shows the typical decomposition of hemicellulose (270˚C - 325˚C), cellulose (325˚C - 400˚C) and lignin (200˚C - 550˚C) with a maximum loss of 75% at 370˚C and the melting point is 320˚C. The results of the sawdust parameters determined in the paper can be valorized to reduce pollutants emissions by developing the efficiency and effectiveness of biomass energy processes and promoting the use of biomass as a sustainable alternative to traditional fossil fuels.

Mechanical and Morphological Properties of Wood Plastic Biocomposites Prepared from Toughened Poly（lactic acid） and Rubber Wood Sawdust （Hevea brasiliensis）

The present research aims to utilize the acrylic Core-Shell Rubber （CSR） particles to reduce the brittleness in Wood Plastic Composites （WPC） prepared from poly（lactic acid） （PLA） and rubber wood sawdust （Hevea brasiliensis）. Experimental works consisted of two major parts. The first part concentrated on toughening PLA by using CSR particles. Mechanical tests revealed that PLA had become tougher with a more than five times increment in the impact strength when the CSR was added at only 5 wt%. The modified PLA was less stiff with the significant reductions of both elastic and flexural moduli and strengths. The second part focused on producing WPC from the toughened PLA and rubber wood sawdust. The tensile moduli and the strengths of the PLA composites increased with rubber wood content. The composites turned out to be more brittle with reductions of both the impact strength and the tensile elongation at break at all the sawdust contents. Toughening PLA/wood flour with 5 wt% CSR improved both the impact strength and the tensile elongation at break. The toughness enhancement was also depicted by the plastic deformation observed on the surfaces of fractured PLA/CSR/wood sawdust composites.

Optimizing Methylene Blue Removal from Textile Effluents: Comparative Study of Adsorption Efficiency Using Raw and Activated Carbon Derived from Gmelina Wood Wastes

This research investigates the efficacy of activated Gmelina Wood Sawdust (GWS) as an adsorbent for the removal of methylene blue (MB) dye from aqueous solutions, in comparison with raw GWS. The study employs laboratory experiments to assess the percentage of dye removal across various temperature and pH conditions. The adsorption process is scrutinized under different parameters, encompassing contact time, initial dye concentration, adsorbent dosage, temperature, and pH. Results demonstrate that activated GWS surpasses its raw counterpart, showcasing superior MB dye removal percentages. Extended contact times increased initial dye concentrations, and higher adsorbent dosages contribute positively to removal efficiency, while temperature exhibits an inverse relationship with dye removal. Optimal adsorption occurs at a pH of 7.0, aligning with the adsorbent’s zero-point charge (pHzpc), underscoring the role of surface charge in the adsorption process. This study underscores the potential of activated GWS as an economical and promising adsorbent material for addressing pollutants. Furthermore, the utilization of activated carbon derived from abundant agricultural waste underscores an environmentally conscious approach to adsorption applications. The ability to tailor the size and properties of activated carbon particles opens avenues for optimizing adsorption capabilities, thereby presenting opportunities for enhanced water treatment solutions.

Evaluation of Sawdust and Rice Husks as Fillers for Phenolic Resin Based Wood-Polymer Composites

We produced Wood-Polymer Composites (WPCs) with phenolic resin (PR) filled with saw dust (SD) and rice husks (RH) in a PR:fillerratio of 60:40 wt.%. RH and SD were grinded and sieved into particles μm. The aim of this research work was to evaluate sawdust and rice husks as fillers for sustainable phenolic resin based WPCs. Therefore, we investigated the thermal stability of PR/RH and PR/SD WPCs then we studied and compared the tensile, flexural properties of PR/SD and PR/RH WPCs samples, as well as their dimensional stability after water absorption test. Furthermore, through ultraviolet light exposure, we evaluated the effects of photo-oxidation on the water stability and mechanical properties of PR/RH and PR/SD WPCs samples compared to unexposed ones. PR filled with SD presented better mechanical properties compared to PR/RH WPCs samples. However, PR/RH WPCs showed good mechanical properties, and better thermal resistance and better water repulsion capabilities compared to PR/SD WPCs samples. Although, long time UV exposure ended up lowering considerably the mechanical properties and water resistance of PR/SD and PR/RH WPCs, both RH and SD offer great added value as fillers for PR based WPCs;SD having better interactions with PR matrix compared to RH.

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。

活性染料对木屑染色拼色的工艺优化

木屑作为木材加工的副产物,其产量在急剧增加。目前,人们基本采用酸性染料对木材进行染色,但着色的只是木质素部分,而占木材主要成分的纤维素和半纤维素并未上染。文章主要研究了前处理及活性染料染色拼色工艺对木屑日晒色牢度和水洗色牢度的影响,确定木屑色牢度较好时的染色工艺。结果表明:当染色温度为40℃、固色温度为60℃、染色时间为60 min时,经前处理后的木屑水洗和日晒色牢度较好。

Chemical characterization of smoke from the production process of wood-plastic composites

The chemical composition of unpleasant smell, emitted from the production process of wood-plastic composites using Manchurian ash sawdust （Fraxinus mandschurica Rupr.） and polypropylene powder as the raw material, was investigated. Wood sawdust and polypropylene powder were subjected to heat treatment to 290℃ during 8 min （the conditions were similar to those employed on an industrial scale）. The emitted compounds were collected and analyzed by gas chromatography-mass spectrometry （GC-MS）. The analytical results showed that the unpleasant smell was emitted from the pyrogenation of wood sawdust rather than from the polypropylene powder. Nine types of compounds （hydrocarbons, ethers, phenols, aldehydes, ketones, alcohols, acids and their derivatives, furan and its derivatives, and nitrogen-containing compounds） were collected in the gas phase during heating. Among those 126 components detected by GC-MS, 112 compounds were identified.

水热及水热氧化预处理对木屑成型颗粒理化性质的影响

生物质成型处理可以提高生物质的能量密度而降低其运输与储存成本,有利于生物质资源的综合利用。该研究以杉木屑为研究对象,经170~260℃水热及水热氧化预处理后制备成型颗粒,并使用范式法、X射线衍射仪和热重分析仪等测试手段分析了水热及水热氧化预处理过程对木屑及其成型颗粒理化性能的影响。结果表明:与原料相比,水热及水热氧化预处理后木屑成型颗粒的机械性能从原料的16.2 MPa分别增至38.9和41.1 MPa,水热氧化预处理对木屑的机械性能提升更有效。在水热及水热氧化预处理过程中,随着预处理温度上升,木屑样品的结晶度均呈现先升高后降低的趋势,分别在230和200℃时达到最高值,且成型颗粒的机械性能与木屑中纤维素含量及其结晶度呈正相关趋势,结晶纤维素是影响其成型过程的关键组分。与原料相比,水热及水热氧化预处理明显改善了木屑成型颗粒的燃料品质及其燃烧性能,成型燃料的热值、综合燃烧指数和稳燃指标均得到明显提升,其中水热氧化处理更有利于木屑炭化程度的提升。

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。

不同基质栽培黑木耳的营养成分分析

对以桑枝屑、梨枝屑、杂木屑为主要基质栽培的黑木耳的常规营养成分、氨基酸、总黄酮、1-脱氧野尻霉素(1-Deoxynojirimycin,1-DNJ)、维生素和微量元素含量等进行检测,探讨不同基质栽培的黑木耳的营养成分之间的差异。结果表明,桑枝屑黑木耳中的总糖、粗纤维、碳水化合物、黄酮、微量元素钙和磷含量较高,梨枝屑黑木耳中氨基酸总量、铁、锌、维生素B1和B2的含量较高,表明桑、梨枝屑可以作为黑木耳栽培的基质加以利用。

废弃生物质在超临界水中转化制氢过程的研究

以废弃生物质转化为富氢气体为目的,使用间歇式超临界水反应器,在反应温度773K～923K、压力15 5MPa～34 5MPa停留时间1min～30min和Ca C摩尔比0～0 56范围内,对木屑在超临界水条件下生成的气体组成及产率进行了考察。实验表明,Ca C摩尔比和温度对木屑转化的影响较大。当Ca C摩尔比为0 48时,碳的气体转化率和氢气产率提高了近一倍。温度从773K提高到923K,碳的气体转化率由47%提高到76%,氢气产率由4 5mmol g上升到6 9mmol g。与温度相比,停留时间和压力的影响不大。

适宜操作条件提高松木屑超临界水气化制氢效果

为了解操作条件对生物质在超临界水中气化制氢过程的影响,该文以松木屑作为原料,在反应温度500℃、反应压力30 MPa、停留时间30 min、木屑质量分数8%、粒径8~16目的条件下,探索了Fe、Na2CO3、Cu SO4 3种催化剂对制氢过程的催化活性:Fe>Na2CO3>Cu SO4。选用Fe催化剂,考察了反应压力30 MPa、停留时间30 min、反应温度(420~500℃)、木屑质量分数(8%~40%)、粒径(2~1 000目)对制氢过程的影响。试验结果表明:Fe催化剂质量分数增大,能显著提高制氢效果;随着温度的升高,气化率、碳气化率、氢气化率及氢气产量均相应增大;木屑质量分数越低,气化率和氢气化率越高;粒径对气化结果影响不大;在优化后的操作条件下(反应温度500℃、反应压力30 MPa、停留时间30 min、Fe质量分数2%、松木屑质量分数8%、粒径8~16目),H2的摩尔分数、氢气化率、氢气产量分别达到42.1%、98.1%、6.62 mol/kg。该文研究结果可为该技术今后的工业化发展和应用提供参考。

杉木屑分段热解制备木醋液及其特性研究

以杉木屑为原料,在固定床反应器上研究了分段热解制备木醋液及其特性。实验结果表明:≥150～250℃为杉木屑热解最活跃阶段,木醋液得率最高,达到34.09%;在该温度段木醋液组分中GC含量最高为酚类物质,其次为酸类物质。木醋液中有机物GC含量随热解温度升高而增加,当热解温度大于150℃后,有机物可达48%左右。不同热解温度段各类有机物GC含量不同,酸类物质在0～150℃最高(64.84%),酚类(54.13%)和酮类(17.95%)物质在≥250～350℃最高,醛类物质在≥150～250℃最高(17.15%)。

固定化硫杆菌对硫化氢的脱除研究

筛选驯化得到一株具有较高脱硫活性的嗜中性硫杆菌,建立以木屑为固定化载体的生物反应器,研究其处理H2S废气的效果。实验表明,木屑是固定床生物反应器中的良好吸附载体。当通气速率范围为6～18 L.h-1,反应器可达到一个临界进气负荷并获得530 g.m-3.h-1的最大脱除负荷(脱除率为80%);而在21～36 L.h-1的高气速下,则无明显的进气负荷临界点。对于SO42-生成情况的实验研究发现,进气硫负荷一定时,SO42-浓度随通气速率升高而提高;通气速率一定,进气硫负荷在小于450 g.m-3.h-1的范围内时,SO42-生成浓度较高;而在大于450 g.m-3.h-1的较高范围,SO42-生成浓度低,H2S被大量氧化为S0,是单质硫回收的较优范围。利用Michaelis-Menten方程,建立脱除H2S的宏观动力学模型,并利用非线性拟合进行动力学预测,预测结果与实验数据的相似度R2均在0.95以上。

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。

热解工艺对木醋液制备及性质的影响

以杉木屑为原料,在固定床反应器上探讨了热解条件对杉木屑制备木醋液及其性质的影响,结果表明:热解温度是主要影响因素,在热解温度450℃、升温速率10℃/min、氮气流量100 mL/min的热解工艺下,粗木醋液产率可达57.13%,精制醋液产率可达38.20%。杉木屑热解制备得到的木醋液的6类主要化学成分中,酸类和酚类物质为主要成分,约占总含量的2/3,其次是醇类、酮类和醛类,酯类含量较少。热解工艺条件对木醋液的组成和含量有显著影响,热解温度影响酸类、酚类和醇类含量,升温速率影响酸类和醇类含量,氮气流量影响酚类和醇类含量,酮类、醛类和酯类含量基本不受影响。

^（60）COγ辐射引发的木材自由基

木材经γ辐照后，高聚物分子的共价键断裂而产生自用基。主谱ｇ０＝２．０１９３的自由基随辐射剂量Ｄ按指数率Ｙ＝１－ｅ^（ａａＤ）规律增长，最后趋于饱和。辐射引发自由基强度与树种有关。机械自由基强度大的木屑，辐射引发自由基强度也大。

落叶松鲜针叶精油的化学成分及杀虫活性研究

采用同时蒸馏萃取(SDE)法以正己烷为溶剂提取落叶松鲜针叶精油,并对其进行了气相色谱-质谱(GC-MS)分析,研究了落叶松鲜针叶精油与松木屑木醋液复配物对舞毒蛾2龄幼虫的杀虫活性。结果表明:落叶松鲜针叶精油得率为0.93%,共鉴定出63种成分,总GC含量为98.11%,GC含量最高的化合物为3-蒈烯(12.13%),其次是2,4-二(1-甲基-1-苯基乙基)苯酚(10.71%)。雌舞毒蛾引诱剂(+)-(7R,8S)-7,8-环氧-2-甲基十八烷的GC含量为0.10%。落叶松鲜针叶精油-木醋液(体积比1∶9,稀释至原体积5倍)对舞毒蛾2龄幼虫喷雾法杀虫活性实验的校正死亡率24 h达到83.33%,优于木醋液5倍稀释液,且72 h内无变化。落叶松鲜针叶精油与松木屑木醋液复配能起到增效作用。