本研究以玉米秸秆皮、髓、叶、鞘部位为研究对象,通过多种手段对玉米秸秆不同部位的化学组分及纤维形态进行分析研究.研究结果表明,玉米秸秆全秆纤维束含量为51.19%,杂细胞含量高.其中,玉米秸秆皮中纤维束含量最多,占全秆纤维束的47.96%,α-纤维素含量为36.99%;叶和鞘纤维束含量占比分别为22.33%、23.65%;髓纤维束含量最少,为6.06%;秸秆皮纤维数均长度为1.17 mm,长宽比最大,为80.41,髓部纤维最短,对全秆纤维贡献率最低.

为实现工业大麻秆的高附加值利用,本研究以工业大麻秆为原料,通过测定化学组分,表明其高纤维素含量(41.45%)的基本特性,证实其制备纳米纤维素的可能性.采用TEMPO-NaBr-NaClO催化氧化体系配合超声制备了氧化纳米纤维素(TCNF),并研究其在制备过程中各阶段的形貌、化学结构、结晶度及热稳定性.结果表明,以工业大麻秆为原料制备的TCNF,其直径均匀分布在3～6 nm,保留了纤维素典型的Ⅰ型结构,结晶度为50.8%,具有较好的热稳定性.

本研究通过硫酸水解、超声和TEMPO(2,2,6,6-四甲基哌啶氧化物)氧化3种处理方法分别制备了纳米纤维素(CFR-CNC、CFR-CNF和CFR-TNC)及相应薄膜,对纳米纤维素微观形态、结晶度、热稳定性和化学结构进行了表征,同时比较了纳米纤维素薄膜的形态和机械性能.结果表明,3种纳米纤维素具有不同的长宽比(29.2、163.7、132.2)和结晶度(62.5％、52.8％、43.9％).红外光谱图表明,3种纳米纤维素的纤维素分子结构并未改变,且CFR-TNC成功引入羧基.3种纳米纤维素薄膜中,CFR-CNF薄膜具有较高的拉伸强度(36.6 MPa),CFR-CNC薄膜具有较好的抗形变能力,并且3种薄膜均具有良好的透光性.

以木质素和间苯二胺为前体,通过简单的一步水热法合成了蓝色发光碳量子点(B-CQDs),进一步通过硝酸氧化作用,合成了绿色发光碳量子点(G-CQDs);通过紫外吸收光谱、荧光光谱、TEM、FT-IR和XPS对两种CQDs的光学性质和结构特征进行表征分析,并测试了G-CQDs的细胞毒性及细胞成像性能.结果表明:硝酸在G-CQDs的合成中起着重要的作用,硝酸的氧化作用使CQDs石墨N含量增加,石墨化程度加深,表面态被钝化,荧光发射波长红移.结构性质分析表明所制备的B-CQDs和G-CQDs主要由C、N、O这3种元素构成,表面都具有—OH、—NH、C—O和—COOH等丰富的亲水基团,在水中是单分散的,平均粒径分别为1.3和2.5 nm.光学性质分析表明B-CQDs和G-CQDs的特征激发波长分别为392和446 nm,对应的发射波长分别为488和514 nm.B-CQDs和G-CQDs分别表现出激发相关的发射行为和激发无关的发射行为.研究发现G-CQDs的可能发射机制属于基于共轭π-域的带隙荧光发射.所合成的G-CQDs具有优异的光致发光、稳定的荧光和低细胞毒性等优点,可以应用于HeLa细胞生物成像.

以玉米秸秆为原料,研究玉米秸秆皮、髓纤维素的性质.玉米秸秆皮、髓分别用苯-醇抽提后,进一步用亚氯酸钠在酸性环境下脱除木质素,最后用氢氧化钾脱除多戊糖,得到玉米秸秆皮、髓纯化纤维素.结果表明,秸秆皮中纤维束排列更整齐紧密,秸秆皮和髓化学组分相似.从秸秆皮、髓得到的纯化纤维素得率分别为38.9％和38.2％,其中α-纤维素含量为87.5％和82.4％,绝大多数多戊糖和木质素被脱除.秸秆皮、髓纯化纤维素的晶型结构仍为纤维素Ⅰ型,结晶度由纯化前的51.2％和30.4％提高到67.7％和42.1％;纯化纤维素的起始分解温度和最高分解温度相对于秸秆皮、髓均提高,热稳定性优于玉米秸秆皮、髓.

This work assessed the fabrication of nitrogen-doped CQDs (NCQDs) from alkali lignin (AL) obtained from spruce, representing a green, low-cost biomass generated by the pulp and biorefinery industries. The AL was found to retain its original lignin skeleton and could be used to produce NCQDs with excellent photoluminescence properties by one-pot hydrothermal treatment of AL and m-phenylenediamine. These NCQDs exhibited blue-green fluorescence (FL) with excitation/emission of 390/490 nm under optimal conditions. The NCQDs showed pH and excitation wavelength-dependent FL emission behaviors. On the basis of the exceptional selective response of these NCQDs to specific solvents, we developed a FL probe for the detection of formaldehyde (FA). The FL intensity of NCQDs was found to be directly proportional to the concentration of FA in the range of 0.05 to 2 mM (R 2 = 0.993), with a detection limit of 4.64 µM (based on 3σ/K). A composite film comprising NCQDs with poly(vinyl alcohol) was found to act as a sensor with a good FL response to FA gas. When exposed to gaseous FA, this film exhibited increased FL intensity and transitioned from blue-green to blue. A mechanism is proposed in which the NCQDs react rapidly with FA to generate Schiff bases that result in enhanced FL emission and the observed blue shift in color.

采用单因素实验法和响应曲面法,以杨木碱浸渍废液的木质素去除率和B/C为评价指标,探究了漆酶与杨木碱浸渍废液在充氧条件下的最佳作用条件.单因素实验通过设置多个实验梯度确定因素最佳范围,再在最佳范围内每个因素设置3个水平进行响应曲面分析,探讨了漆酶投加量、反应温度、反应时间3个因素对处理效果的影响,从而确定出最佳作用条件.实验结果表明,最佳作用条件:漆酶投加量157 U/L,反应温度37℃,反应时间4.56 h,在此条件下,预测木质素去除率为42.66％,B/C为0.758;验证实验得到的木质素去除率为43％,B/C为0.75,与预测值偏差不超过1.06％,优化结果可信.各因素对木质素去除率和B/C影响的大小顺序为漆酶投加量>反应时间>反应温度.

采用红外光谱、紫外光谱、气相色谱-质谱联用仪(GC-MS)定性、定量分析了杨木NaOH常压浸渍废液的污染成分,以确定其污染特性和可生化性评价.结果 表明,废液中含有的有机物结构包括苯环、羟基、醚基、氨基、酚羟基、—OCOR助色基团和羰基等基团;可能含有的有机物种类有烷烃、酚或醇、芳香族化合物、糖、醚类、酚类、羧酸类物质等;相对含量较多的为酯类、烷烃类、芳香族化合物、醛酮类以及有机酸等有机化合物.木质素浓度为2539 mg/L,糖类物质浓度为4728 mg/L;废液的悬浮物浓度、可溶性固形物浓度、可溶性有机固形物浓度分别为4636、4878和860 mg/L;其CODCr、BOD5浓度分别为29216 mg/L和19400 mg/L,C∶N∶P=100.15∶4.62∶1.废液中污染物成分复杂,有机污染物浓度较高,废液具有良好的可生化性.若对废液进行厌氧处理时可能需补充N、P元素.废液中硫酸盐、硝酸盐、亚硝酸盐和氨氮等抑制厌氧处理过程的污染物含量未达到抑制浓度.

In this study, molded fiber products (MFPs) were prepared from lignin compounded with Lewis acid-modified fibers using enzymatic hydrolysis lignin (EHL) as a bio-phenol. The fibers were modified and compounded entirely through hot-pressing. To improve the reactivity of enzymatic lignin, hydroxylated enzymatic hydrolysis lignin (HEHL) was prepared by hydroxylation modification of purified EHL with hydrogen peroxide (H2O2) and ferrous hydroxide (Fe(OH)3). HEHL was mixed uniformly with Lewis acid-modified fibers on a pressure machine and modified during the molding process. The purpose of Lewis acid degradation of hemicellulose-converted furfural with HEHL was to generate a resin structure to improve the mechanical properties of a MFPs. The microstructure of the MFP was shown to be generated by resin structure, and it was demonstrated that HEHL was compounded on Lewis acid-modified fibers during the molding process. The thermal stability of the MFP with composite HEHL did not change significantly owing to the addition of lignin and had higher tensile strength (46.28 MPa) and flexural strength (65.26 MPa) compared to uncompounded and modified MFP. The results of this study are expected to promote the application of high lignin content fibers in molded fibers.

Nanocellulose crystals (NCCs) were successfully prepared via acid hydrolysis from an abundant agricultural waste (tea stalk) in China. The effective factors for NCC yield were modeled by the response surface methodology (RSM). The RSM determined the reaction conditions (H2SO4 concentration, hydrolysis temperature, and reaction time) that optimized the yield of tea stalk NCCs (TNCCs). Under the optimized operating conditions, the fundamental properties of TNCCs were characterized via transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), laser diffraction particle-size analyzer, and scanning probe microscopy (SPM). Wood NCCs (WNCCs) and microcrystalline NCCs (MNCCs) were simultaneously prepared from common wood and microcrystalline cellulose under the same conditions. The results show that TNCCs not only shows similar physical and chemical properties with WNCCs and MNCCs, but also has better stability. Therefore, this study offers novel routes for high-valued utilization of tea stalk and provides some theoretical guidance for utilizing cellulose obtained from tea stalk.

In this study, halloysite (Hal)/cellulose nanofiber (CNF) composite films were prepared using vacuum-filtering assembly method. Microstructures, chemical composition, crystal structures, thermal performances, mechanical properties, and light transmission properties of the composite films were characterized. The results showed that Hal was well uniformly dispersed in the composite films. The interactions between Hal and CNF endowed the formation of a robust network structure, and the surfaces of the composite films were rough by the addition of Hal. X-ray diffraction result showed the crystallinity of CNF declined by Hal, while the thermal stability of the composite films increased remarkably. The tensile strength of the composite films increased compared with pure CNF film, for example, the tensile strength and the elongation at break of the composite film with 3 Hal was 41.9 MPa and 11.7%, respectively. As the content of Hal in the composite film increased, the light transmittance of the composite film decreased, since the addition of Hal led to a growth in the haze of the composite films. The prepared high-performance Hal/CNF composite films show promising application in degradable food package.

Self-bonding natural fiber materials (SNFMs) were prepared at different initial moisture contents (IMCs) through a molding pressing process. The self-bonding mechanism of the SNFMs was deduced from the chemical and structural changes of lignin and their mechanical strengths. The structural transformations of milled wood lignin (MWL) in the SNFMs were investigated by two-dimensional heteronuclear single quantum coherence, quantitative 31P-nuclear magnetic resonance spectra, gelpermeation chromatography, and thermogravimetric analysis. As IMC increased from 0% to 80%, the tensile strength increased from 23.0 to 70.0 MPa and the density increased from 0.99 to 1.05 g/cm3. IMC affected the distribution and abundance of the typical lignin linkages (β-O-4', β-β, and β-5') and the S-OH/G-OH ratios of lignin. Moreover, as IMC increased, the aliphatic hydroxyl groups proportionally decreased, while the condensed phenolic and non-condensed phenolic hydroxyl groups increased, the molecular weight of MWL became larger, and the thermal stability of lignin improved. These findings indicate the simultaneous occurrence of depolymerization and condensation reactions of lignin. The condensation reaction dominated, improving the mechanical strength of the material. Our results explain (at least partly) the self-bonding mechanism of SNFMs.

以橡胶木为原料,通过化学处理得到橡胶木纯化纤维素(PCF),在此基础上通过高速剪切结合超声波处理制备得到纤维素纳米纤丝(CNF).通过单相合成法制备二氧化锰(MnO2)纳米片.以CNF为结构支撑体,MnO2纳米片和碳纳米管(CNTs)作为活性电极物质,通过真空抽滤的方式制备CNF/MnO2/CNTs柔性电极材料.采用多种手段对CNF、MnO2以及电极材料的结构性能进行表征,并测试了电极材料的电化学性能.结构性能表征结果表明:CNF的直径为3 ～10 nm,具有大的长径比,是很好的结构支撑体,CNF为纤维素I型结构;MnO2纳米片为片层花瓣状结构,晶型为δ型.电化学性能测试结果表明:在扫描速率为50 mV/s时电极材料的比电容值为78.45 F/g,在电流密度为0.1 A/g时的电极材料比电容值为97.02 F/g,在低频区时,交流阻抗(EIS)曲线的直线部分斜率较大,表明电极材料具有良好的电容特性,在200次充放电循环测试过程中,电极材料的电容保留率始终维持在99％左右,表明该电极材料具有良好的电化学性能并且具有一定的柔性变形能力,可用作超级电容器的电极材料.

In this study, poplar chemi-mechanical pulp was used as a raw material to investigate the effect of enzymatic hydrolysis lignin (EHL) content on the tensile strength and hydrophobicity of molded fiber materials (MFMs). The tensile strength and hydrophobic properties of the fabricated MFMs with different EHL contents were evaluated, and changes in their microstructure, chemical structure, and thermal stability were characterized via scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric (TG) analysis, respectively. Results show that under the experimental conditions used herein, the addition of EHL could increase the tensile strength and surface water contact angle of MFMs up to 20.3 MPa and 95.0 degrees, respectively. The SEM observations indicate that the addition of EHL expanded the contact area between the EHL and fibers, thereby reducing the holes between fibers. The FTIR and TG analyses indicated that hot-pressing degraded EHL to form small molecular substances and improved the reaction with aldehydes produced via carbohydrate degradation, improving both the inter-fiber bonding strength and hydrophobicity of the MFM surface.

目的 以橡胶木为原料制备纤维素纳米纤丝.方法 通过化学预处理结合高强度超声处理的方法 制备纤维素纳米纤丝;使用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)、傅里叶红外光谱仪(FTIR)、热重分析仪(TG)、紫外分光光度计(UV)和万能材料试验机等设备对其结构和性能进行研究.结果 橡胶木纤维素纳米纤丝的直径为3～10 nm,保留了天然纤维素Ⅰ型结构,具有较好的热稳定性,并且制备的薄膜具有较好的力学性能和透明度.结论 以橡胶木为原料,通过常规的化学预处理结合高强度超声处理的方法,可以制备出与杨木纤维素纳米纤丝的基础特性相似的纤维素纳米纤丝,并且具有较高的产率.

Tea stalk was used for producing carboxymethyl cellulose (CMC), and a response surface methodology was used to model effective factors relative to the degree of substitution (DS). The optimum values of the independent variables were an alkalization time of 107 min, monochloroacetic acid at 3.11 g, and an etherification time of 171 min, at which the CMC had a DS of 0.668. The yield of CMC in optimization condition was 75.9%. The optimized CMC was in a good agreement with the commercial CMC, as based on Fourier transform infrared spectroscopy and X-ray diffractometry analyses. The optimized CMC was used to enhance paper strength, and with economic factors and paper strength enhancement taken into account, the appropriate amount of optimized CMC was determined to be approximately 0.3%. When the amount of optimized CMC was at 0.3%, the tensile index, burst index, tearing index, and folding endurance were 26.7 N m/g, 1.0 kPa m(2)/g, 12.1 mN m(2)/g, and 2.0, respectively. Together, these results indicated that the optimized CMC exhibited comparable paper strengthening properties relative to that of commercially available CMC.

Herein, walnut shell (WS) was utilized as the raw material for the production of purified cellulose. The production technique involves multiple treatments, including alkaline treatment and bleaching. Furthermore, two nanocellulose materials were derived from WS by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation and sulfuric acid hydrolysis, demonstrating the broad applicability and value of walnuts. The micromorphologies, crystalline structures, chemical functional groups, and thermal stabilities of the nanocellulose obtained via TEMPO oxidation and sulfuric acid hydrolysis (TNC and SNC, respectively) were comprehensively characterized. The TNC exhibited an irregular block structure, whereas the SNC was rectangular in shape, with a length of 55–82 nm and a width of 49–81 nm. These observations are expected to provide insight into the potential of utilizing WSs as the raw material for preparing nanocellulose, which could address the problems of the low-valued utilization of walnuts and pollution because of unused WSs.

目的 用简易、经济的方法制备透明柔性、可折叠、力学性能良好的茶梗纳米纤维素基磁性复合膜.方法 以茶梗纳米纤维素晶体(CNCs)为模板,共沉淀合成磁性CNCs;随后将磁性CNCs分散到茶梗纳米纤维素纤丝(NCFs)溶液中;最后通过真空抽滤的方法制备磁性复合膜.结果 磁性CNCs在不需要任何分散剂的情况下,可以均匀地分散在水溶液中,具有良好的超顺磁性;磁性复合膜具有良好的光学、力学和磁学性能,当NCFs质量分数为60％时,透光率、拉伸强度和磁化强度分别达到71.3％,75.03 MPa和12.96 A·m2/kg.结论 制备的磁性CNCs具有良好的分散性和磁学性能;磁性复合膜具有较好磁学和力学性能,可考虑在电磁屏蔽、磁电开关等领域进行应用.

利用实验室自制茶梗纳米纤维素原位合成纳米纤维素(CNC)/四氧化三铁(Fe3O4)纳米球,并对其粒径大小、结晶性质、磁性性能和电化学性能进行分析表征.结果表明,通过原位合成法所制得CNC/Fe3O4纳米球,粒子间分散性良好,直径约为10～30 nm;CNC/Fe3O4纳米球具有磁化强度34.9 A·m2/kg的磁特性;CNC/Fe3O4纳米球表现出良好的电化学性能,CNC/Fe3O4电极的比电容主要是Fe3O4产生的赝电容,在电流密度0.03 A/g时,比容量可达30.14 F/g,在0.04 A/g电流密度下,经过500次充放电后容量保持率为78.76％.CNC/Fe3O4电极中离子的扩散为Warburg机理.

为了解决橡胶木利用价值低的问题,尝试以改性橡胶木纤维素为基体制备水凝胶并应用于染料吸附以提高其利用价值.对橡胶木纤维素(PCF)进行羧甲基化改性,通过反相悬浮聚合法,制备水凝胶;以不同pH值的缓冲溶液为介质研究水凝胶的水溶胀性能;在不同浓度的缓冲溶液中研究水凝胶对罗丹明B(RhB)的吸附.结果表明,制备的球形水凝胶有一定的pH敏感性,并且对RhB的吸附性能良好,在pH为10、RhB浓度为1200 mg·L-1的缓冲溶液中,添加 κ-卡拉胶的水凝胶对RhB的吸附容量为546.81 mg·g-1.该球形水凝胶在染料吸附领域具有潜在应用价值.