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《林业科学》2021,57(7)
【目的】探究马尾松树皮纳米木质纤维素气凝胶吸附剂对Cr~(3+)、Cu~(2+)、Pb~(2+)、Ni~(2+)的吸附性能,阐明马尾松树皮和纳米木质纤维素气凝胶吸附重金属离子的相关机理,以更好地利用农林废弃物马尾松树皮制备出成本低廉、便于产业化的生物质吸附材料,为其大规模应用奠定理论基础。【方法】将抽提后的马尾松树皮绝干样品在80℃水浴加热搅拌条件下使用对甲苯磺酸溶液处理1 h,反应结束后趁热过滤并透析滤渣。滤渣样品通过微射流均质机20次,得到马尾松树皮纳米木质纤维素。固含量2%的马尾松树皮纳米木质纤维素样品-20℃冷冻120 min后进行冷冻干燥,得到马尾松树皮纳米木质纤维素气凝胶。研究马尾松树皮纳米木质纤维素气凝胶吸附剂对Cr~(3+)、Cu~(2+)、Pb~(2+)、Ni~(2+)的最大吸附容量(q_e)以及其等温吸附特性、吸附热力学特性和吸附动力学特性。【结果】马尾松树皮纳米木质纤维素气凝胶吸附剂对Cr~(3+)、Cu~(2+)、Pb~(2+)和Ni~(2+)的最大吸附容量(q_e)分别为132.7、130.4、186.7和123.4 mg·g~(-1)。马尾松树皮纳米木质纤维素气凝胶吸附Cr~(3+)符合Temkin等温吸附(R~2=0.990 1),且为不均匀的单层吸附。吸附热力学特性研究表明,马尾松树皮纳米木质纤维素气凝胶吸附Cr~(3+)的过程符合热力学规律,R~2=0.992 9,且为非自发复合吸附过程,升高温度对吸附过程的促进作用与放热反应对吸附过程的抑制作用甚至会出现相互抵消的情况。马尾松树皮纳米木质纤维素气凝胶吸附Cr~(3+)符合准二级动力学模型(R~2=0.991 0),其吸附Cr~(3+)的速率主要受化学作用而非物质传输步骤影响,特别是二者之间电子的化学分享或共价键交换等过程。【结论】基于廉价的生物质———马尾松树皮制备的马尾松树皮纳米木质纤维素气凝胶可作为重金属离子的有效吸附剂,表现出较为理想的吸附容量,静态吸附涉及的条件较为简单,具有一定的可试验推广性,马尾松树皮基吸附剂的开发也可推动廉价生物质的资源化利用。马尾松树皮和纳米木质纤维素气凝胶2种吸附剂的吸附性能稳定可靠,有望通过优化工艺提升性能;但是需要基于大规模甚至中试规模试验才能检验其有效性,进而指导工艺优化,得到性能更加出色的马尾松树皮纳米木质纤维素气凝胶作为重金属离子吸附剂。 相似文献
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采用蔗渣纤维素、丙烯酸(AA)、丙烯酰胺(AM)、甲基丙烯酰氧乙基三甲基氯化铵(MAETAC)为原料,通过接枝共聚反应制备出一种新型纤维素吸附剂,对制备该吸附剂的影响因子如碱化时间、碱质量分数、单体的用量、引发剂(NaHSO3、(NH4)2S2O8)用量、温度和时间等条件进行了分析研究.该纤维素吸附剂的最佳合成工艺为:碱化时间90 min,NaOH质量分数30%,AA中和度60%,相对于吸附剂整体,纤维素质量占20%,单体AA占47.3%,AM占26.3%,MAETAC占6.4%,引发剂占2.6%(相对于单体用量),反应温度70℃,反应时间3 h.该工艺条件下所得吸附剂对Cu2 的吸附量达25.1 mg/g. 相似文献
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以纤维素为原料,以甲基丙烯酰氧乙基三甲基氯化铵(METAC)、丙烯酰胺(AM)、 2-丙烯酰胺基-2-甲基-1-丙烷磺酸(AMPS)为单体,过硫酸钾为引发剂,通过一步自由基聚合法制备得到两性纤维素基共聚物(CO-AC)吸附剂。采用元素分析仪、红外光谱(FT-IR)仪对CO-AC的结构与性能进行了表征,发现季胺基、酰胺基和磺酸基等活性基团成功被引入到纤维素分子链中。以CO-AC对NH+4和H2PO-4的去除率和平衡吸附量为考核指标,对吸附条件进行了优化,探讨了不同因素对吸附效果的影响。研究结果表明:当纤维素葡萄糖单元与AMPS、AM和METAC的物质的量之比为1∶2∶3∶3时,制备的吸附剂吸附效果最佳。在50 mL质量浓度为150 mg/L的NH+4和H2PO-4溶液中,当CO-AC添加量为100 mg, pH值为7时,对NH+4 相似文献
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美国杂交柳树具有林木能量密度高、生物量大、种类丰富、引种容易等优点,是实现大规模能源化的理想生物资源。在概述美国杂交柳作为能源林应用与发展现状的基础上,就其木纤维最长可达1mm、且综纤维素含量超过70%、木质素含量低的特点,重点报道了美国杂交柳在制浆造纸、活性炭、生物酒精、微晶纤维素、人造板生产等多方面的发展优势,为杂交柳树的大面积推广提供了相应的理论基础。 相似文献
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《林产化学与工业》2018,(6)
以桉木浆为原料,经TEMPO氧化制得羧基化纳米纤维素(CNC)、再经高碘酸钠氧化制得双醛基纳米纤维素(DANC),最后利用二乙烯三胺(DETA)通过席夫碱反应对其进行氨基化改性,得到端氨基纳米纤维素(ANCC)。采用多种方法对纳米纤维素的结构和性能进行了表征,结果表明:DANC含醛基为2.95 mmol/g,ANCC含氨基为1.7 mmol/g,DETA上的氨基成功地接枝到了纳米纤维素链上,使得分子链变长,ANCC的热稳定性提高。ANCC对Pb(Ⅱ)的吸附性能研究表明:室温条件下,当ANCC吸附剂用量为0.1 g,溶液初始质量浓度为400 mg/L且p H值为5.0的条件下吸附3 h,吸附量为210.15 mg/g。吸附过程符合准二级动力学吸附模型和Langmuir等温吸附模型,说明其吸附过程主要为单分子层的化学吸附。 相似文献
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In our preceding study, we clarified that liquids having similar molecular sizes to ethanol were mainly adsorbed onto lignin
among the major constituents of wood. This suggests that most micropores or adsorption sites loosely hydrogen-bonded to each
other, which are accessible to these liquids, exist in lignin. In the present study, to examine micropores in wood and lignin,
micropore distribution was measured by CO2 gas adsorption at ice-water temperature (273 K). Dry samples prepared by gradual delignification from wood meal were used
as adsorbents. The pore-size distributions were determined by analyzing adsorption isotherms using the Horvath-Kawazoe method.
It was found that the number of micropores decreased with the decrease in residual lignin, and micropores were hardly found
in cellulose and hemicellulose. It is considered that most micropores smaller than 0.6 nm in wood exist in lignin. 相似文献
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【目的】将微波加热与甘油利用相结合的综合炼制工艺用于木质纤维素生物质预处理,探索其在燃料乙醇制备中的可行性,为实现经济可行、经济有效的木质纤维素生物质酶解预处理技术和生物燃料生产提供基础信息。【方法】以银腺杨、日本落叶松、刚竹和柳枝稷为试验材料,采用微波液化法对其进行液化处理,将液化产物分为纤维素、半纤维素和木质素组分,并对纤维素纤维组分进行综合表征。【结果】化学分析结果表明,纤维素纤维具有较高的葡聚糖含量;红外光谱显示,木质素和半纤维素的信号逐渐减弱,说明半纤维素和木质素经液化处理后有效脱除;XRD分析结果表明,纤维素纤维结晶度高、表面积大。【结论】相比原木质纤维素生物质,银腺杨、日本落叶松、刚竹和柳枝稷4种原材料纤维素纤维的酶解糖化效率均有不同程度提升(最高酶解转化率可达70%),液化固体产物--纤维素纤维在制备燃料乙醇中具有广阔的潜力和前景。 相似文献
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Rashmi Kumari Hirokazu Ito Masahiro Takatani Miho Uchiyama Tadashi Okamoto 《Journal of Wood Science》2007,53(6):470-480
Although wood/cellulose-plastic composites (WPC) of low wood/cellulose content have been more accepted worldwide and are promoted
as low-maintenance, high-durability building products, composites containing high wood/cellulose content are not yet developed
on an industrial scale. In this study, flow properties, mechanical properties, and water absorption properties of the compounds
of cellulose microfiber/polypropylene (PP) and maleic anhydride-grafted polypropylene (MAPP) were investigated to understand
effects of the high cellulose content and the dimensions of the cellulose microfiber. The molding processes studied included
compression, injection, and extrusion. It was found that fluidity is not only dependent on resin content but also on the dimension
of the filler; fluidity of the compound declined with increased fiber length with the same resin content. Dispersion of the
composite was monitored by charge-coupled device (CCD) microscope. Increasing the plastic content in the cellulose-plastic
formulation improved the strength of mold in addition to the bond development between resin and filler, and the tangle of
fibers. The processing mode affected the physicomechanical properties of the cellulosic plastic. Compression-molded samples
exhibited the lowest modulus of rupture (MOR) and modulus of elasticity (MOE) and the highest water absorption, while samples
that were injection-molded exhibited the highest MOR (70 MPa) and MOE (7 GPa) and low water absorption (2%). 相似文献
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低成本纤维素酶的生产是酶法转化纤维质生物量为酒精的关键。尽管已有很多有关纤维素酶的研究报告,但底物的预处理对固态发酵过程中pH值和产酶的影响很少见诸于报道。作者研究了在固态发酵过程中,里氏木霉在未处理和经挤压处理的麦糟培养基上pH值的变化。经单螺杆和双螺杆挤压的麦糟,其纤维的结晶度变化较小。单螺杆挤压撕开了纤维结构,而双螺杆破坏并摧毁了纤维细胞的细胞壁,同时麦糟的颗粒也变得很小。两种经挤压处理的麦糟均有利于菌体的生长,并提高了产酶。以单螺杆挤压处理的麦糟为培养基时,最高FPA酶活力为182.8IU/g纤维素。 相似文献
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The sawdust of oak and black locust hardwood was found to have good adsorption capacities for heavy metal ions. The leaching
of coloured organic matters during the adsorption can be prevented by each of the following pre-treatments of adsorbents:
with formaldehyde in acidic medium, with sodium hydroxide solution after formaldehyde treatment, or with sodium hydroxide
only. The studies indicated that the leaching of coloured matters from modified hardwood sawdust was less than that from unmodified
hardwood sawdust, namely between 70 and 94%, dependent on wood species and the method of modification. At the same time, adsorption
capacities of modified adsorbents were higher than unmodified adsorbents when sodium hydroxide was applied for modification.
When formaldehyde was applied for modification, the adsorption capacities of adsorbents remained unchanged. Only the application
of sodium hydroxide was recommended for modification of hardwood sawdust. 相似文献
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植物纤维数量庞大和可再生性使得纤维乙醇产品成为目前全世界生物质可替代液体燃料开发的重点,这正是植物纤维水解工业为什么会得到发展的原因。 相似文献
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以香牙蕉(Musa cavendisihii,Me)的假茎纤维为原料,对它的水分、灰分、水溶物、脂肪和蜡质、果胶、木质素、半纤维素、含胶率和纤维素成分进行了分析。结果表明:纤维素是构成香蕉假茎纤维的主要成分,占总量的55.591%;胶质总含量41.948%,其中脂蜡质含量1.438,果胶含量6.975%,木质素含量8.742%,半纤维素含量17.378%。与其它植物纤维相比,虽然香蕉假茎纤维含纤维素量中等,含木质素较高,但仍然有开发价值。 相似文献