木质素纳米炭的制备及作为锂离子电池负极的性能研究

采用生物炼制工业中残渣提取的酶解木质素与乙酸锌在碱性条件下水热复合, 制备出低分子量木质素/氧化锌复合物(LWL/ZnO), 再通过碳化和酸洗后得木质素纳米炭材料(NLC). 通过对其形貌结构进行表征后发现, NLC呈粒径小于50 nm的纳米颗粒结构, 比表面积为833.25 m²/g, 介孔率高达58.07%, 其中孔径约10 nm的介孔发达. 电化学性能测试结果表明, NLC作为锂离子电池负极材料具有良好的循环性能和倍率性能, 在200 mA/g的电流密度下循环200次后仍能保持705 mA·h/g的可逆比容量.     

苯胺与吡咯共聚物空心球的自组装制备及性能

以碱性溶液为反应介质,苯胺和吡咯为单体,采用稀释聚合法制备苯胺-吡咯共聚物自组装空心微球.研究了搅拌条件、共聚单体摩尔比、聚合反应介质和聚合时间对共聚物形貌的影响.采用扫描电子显微镜、透射电子显微镜、红外光谱、广角X射线衍射、热重分析仪和四探针技术表征了共聚物的形貌、结构和性能.研究结果表明,聚合反应条件对共聚物的形貌有重大影响,通过调整聚合反应条件,可以实现共聚物形貌的有效调控.共聚单体总摩尔浓度为0.05 mol/L,氨水溶液作为反应介质,在静态条件下反应24 h可以得到尺寸均一、平均外直径为610～863 nm,壳厚144～162 nm的自组装共聚物空心微球.同时,研究了共聚物对银离子的吸附性能,结果表明共聚物对银离子有还原作用,吸附后共聚物表面有纳米银的生成.     

介孔碳-镍复合物对甲基橙的吸附性能研究

以三嵌段共聚物(F127)作为表面活性剂,低分子量酚醛树脂和六水合硝酸镍分别作为碳源和镍源,利用挥发诱导自组装方法制备了有序介孔碳-镍纳米复合物;采用X射线衍射仪和透射电子显微镜分析了复合物的相组成和微结构;测定了样品的氮气吸脱附特性和对甲基橙的吸附性能,采用二级动力学方程和吸附等温线对吸附结果进行了拟合.结果表明,镍纳米微粒的平均粒径约为20nm;当纳米镍的负载量为2%时,复合物样品具有很高的Brunauer-Emmett-Teller(BET)比表面积(1 610m2/g)和较大的孔容(1.29cm3/g).与此同时,复合物样品的氮气吸脱附特性与二级动力学方程拟合结果具有很好的相关性,吸附量高达324mg/g;吸附等温线拟合结果表明,样品对甲基橙的吸附过程为单分子层吸附,与Langmuir吸附等温式的相关性良好.     

壳聚糖改性织物中原位合成银纳米粒子

采用壳聚糖改性棉和涤纶织物,通过织物表面的壳聚糖原位吸附、还原银离子制备了纳米银抗菌织物.用场发射扫描电子显微镜(SEM)、X射线能谱(EDA)、X射线粉末衍射仪(XRD)和反射光谱等对纳米银织物进行了表征,研究了银离子浓度和壳聚糖浓度对纳米银织物的影响,并检测了纳米银织物的抗菌性能.结果表明,在无需任何还原剂的条件下,壳聚糖改性的棉和涤纶织物表面可以均匀地形成银纳米粒子,晶粒大小为5~10 nm,所制备的纳米银织物均具有优异的抗菌性能.     

木质素磺酸钠改性聚砜膜的制备及其在正渗透膜中的应用

采用木质素磺酸钠作为亲水添加剂,通过浸没沉淀相转化法制备了木质素磺酸钠共混改性聚砜膜,以改善聚砜膜的亲水性,并用作正渗透膜的支撑层,以降低内浓差极化效应.利用扫描电子显微镜、衰减全反射傅里叶变换红外光谱仪、水接触角仪等研究了不同木质素磺酸钠添加量对聚砜膜的结构和表面性质的影响.结果表明,添加木质素磺酸钠后,聚砜膜的指状孔变得规整且狭长.水接触角实验证实添加木质素磺酸钠能改善聚砜膜的亲水性,当木质素磺酸钠含量为0.4 wt%时,聚砜膜的表面水接触角可降低至65°.正/反渗透测试装置分别用于表征正渗透膜的传质性质和结构参数.结果表明,以0.4 wt%木质素磺酸钠改性聚砜膜为支撑层的正渗透膜的水渗透性能(A=3.12×10~(-5) LMH×Pa~(-1))优于纯聚砜基底正渗透膜(0.76×10~(-5)LMH×Pa~(-1)),而且前者的结构参数(S=2010mm)远小于后者(3450mm),说明木质素磺酸钠改性聚砜膜有效弱化了正渗透膜的内浓差极化效应.     

固定漆酶聚苯胺-CoC2O4纳米复合物修饰电极的直接电化学

采用循环伏安法、微分脉冲伏安法、交流阻抗谱以及计时电流法等电化学方法,结合红外光谱、紫外-可见分光光度法、原子力显微镜、透射电子显微镜以及原子吸收光谱等辅助手段,表征了固定漆酶的聚苯胺-草酸钴纳米复合物的化学组成、结构和形貌,测试了纳米复合物固酶前后的导电性能的变化,研究了纳米复合物修饰电极上固定漆酶的直接电化学行为,评估了该电极的催化氧还原效能以及作为电化学传感器检测氧分子的性能。实验结果表明该电极在不含电子介体的溶液中以酶活性中心T2作为首要电子受体,将得到电子传递给化学吸附的氧气使其被电还原,其表观电子迁移速率为0.017 s~(-1),且具有良好的催化氧还原性能(氧还原起始电位:460 m V vs NHE,转化氧分子为水的表观速率常数为2.6×10-4 s~(-1)),酶电催化氧还原为水分子步骤为反应的速控步。该电极作为电化学传感器对氧具有极低检测限(0.20μmol·L~(-1)),宽线性响应范围(0.4~7.5μmol·L~(-1))以及对底物高亲和力(KM=122.4μmol·L~(-1))等优势。     

聚羟基丁酸酯/碳纳米管复合纳米纤维膜的制备及其对重金属离子吸附分离性能的研究

以聚羟基丁酸酯和碳纳米管为原料,采用三氯甲烷/二甲基甲酰胺混合溶液为溶剂,利用静电纺丝技术制备了聚羟基丁酸酯/碳纳米管复合纳米纤维膜.研究了碳纳米管的含量对纳米纤维膜形貌和力学性能的影响,探讨了复合纳米纤维膜对重金属Cu(II)、Cd(II)和Pb(II)的吸附特性.实验结果表明:加入1 wt%碳纳米管能够将纳米纤维的平均直径从(728±146)nm降低至(468±89)nm,纳米纤维膜的比表面积从27.24 m~2/g提高至43.45 m~2/g;碳纳米管的复合能够有效增强聚羟基丁酸酯纳米纤维,当碳纳米管含量1 wt%为最佳,拉伸强度可达5.85 MPa,较纯聚羟基丁酸酯纳米纤维提升了115%.复合纳米纤维膜对重金属离子具有良好的吸附特性,其对Cu(II)、Cd(II)和Pb(II)的最佳吸附pH值为5,此时最大吸附容量分别为91.04、171.05和197.03mg/g,平衡吸附时间分别约为50、60和60 min,吸附率分别为1.79、2.83和3.28 mg/g/min;热力学和动力学分析表明,复合纳米纤维膜对重金属Cu(II)、Cd(II)和Pb(II)的吸附行为更符合Freundlich模型,吸附过程更符合Pseudo-second order模型;循环使用实验表明,重复使用5次后,其吸附容量可保持在初始值的87%以上,具有较好的使用寿命.     

二氧化硅/木质素多孔碳复合材料的制备及作为锂离子电池负极材料的性能

将来源于造纸黑液中的碱木质素(AL)通过水热反应与纳米二氧化硅(SiO_2)复合,制备了二氧化硅/季铵化碱木质素复合物(SiO_2/QAL),再经过碳化和酸洗后得到二氧化硅/木质素多孔碳复合材料(SiO_2/PLC).形貌与结构表征结果表明,SiO_2/PLC的比表面积达到1069 m~2/g,具有平均孔径约20 nm的介孔结构.二氧化硅纳米颗粒均匀分散在三维网络结构的木质素多孔碳内部.电化学性能测试结果表明,SiO_2/PLC作为锂离子电池负极材料具有良好的倍率性能和循环性能,在100 mA/g电流密度下经过100周循环后放电比容量为820 mA·h/g,在5 A/g大电流密度下嵌锂容量达到235 mA·h/g.     

HRP-纳米金/纳米硫化镉/聚天青Ⅰ修饰玻碳电极的制备及用作过氧化氢生物传感器

以玻碳电极为基底,电聚合一层表面均匀的带正电性的聚天青Ⅰ膜,再通过静电作用吸附一层带负电性的具有大比表面积的纳米硫化镉来固定纳米金和辣根过氧化物酶(HRP)的复合物,制备出性能良好的过氧化氢生物传感器.采用循环伏安法(CV)和计时电流法对该生物传感器的性能进行了研究.试验表明:该方法不仅增加了酶的吸附量,还有效保持了酶的生物催化活性,此生物传感器对过氧化氢浓度在4.0×10-7～1.2×10-3mol·L-1范围内呈线性关系,检出限为1.4×10-7mol·L-1.     

对-特辛基酚表面印迹聚合物的制备及吸附性能评价

以对-特辛基酚为模板、甲基丙烯酸为功能单体制备了对-特辛基酚表面印迹聚合物.采用扫描电子显微镜、紫外光谱以及红外光谱对印迹聚合物进行表征,通过平衡吸附实验对聚合物的吸附性能进行评价.结果表明:该分子印迹聚合物对对-特辛基酚具有较大的吸附容量和良好的选择性,其最大吸附量Qmax约为86.12mg/g.     

Nanocomposite hydrogel from grafting of acrylamide onto HPMC using sodium montmorillonite nanoclay and removal of crystal violet dye

Hydrogel nanocomposites were synthesized from grafting of acrylamide onto hydroxypropyl methylcellulose using methylenebisacrylamide crosslinker and sodium montmorillonite (Na-MMt) nanoclay. The effect of nanoclay content on the swelling of nanocomposites was investigated and an optimum swelling capacity was obtained at 12.7 wt% of Na-MMt. The effect of salt solutions on the swelling of nanocomposites revealed that the degree of swelling of samples depends only slightly on the salinity. The structure of nanocomposites was characterized by XRD, SEM, FTIR, and TEM techniques. The XRD and TEM results confirmed the exfoliation of Na-MMt nanoclay in nanocomposite matrix. The morphology of the nanocomposites was characterized by SEM technique and according to the results a loose surface was observed. The nanocomposite hydrogels were evaluated to remove cationic crystal violet dye from water. The investigation of the dye adsorption capacity and rate of nanocomposite hydrogels as a function of Na-MMt content revealed that the both adsorption capacity and rate is enhanced as the nanoclay content is increased in nanocomposite composition. The experimental equilibrated adsorption capacity of nanocomposites was analyzed using Freundlich and Langmuir isotherm models. The best fit to the experimental data was obtained with the Langmuir model.     

Melt‐blending of unmodified and modified cellulose nanocrystals with reduced graphene oxide into PLA matrix for biomedical application

In this article, we successfully fabricated the bionanocomposites using cellulose nanocrystals (CNCs) and reduced graphene oxide (rGO) reinforced into biodegradable polylactic acid (PLA) matrix through melt‐mixing method. Due to the affinity difference between hydrophilic CNC and hydrophobic PLA, the surface modification of CNC was employed using quaternary ammonium salts (CTAB) as a surfactant. The nanocomposites were developed using different blend ratios of CNC/modified CNC (1, 2, and 3) wt% and (0.5 wt%) rGO into the polymer matrix. The morphology of CNC, q‐CNC (modified CNC), and nanocomposites were inspected by atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM). It is demonstrated from tensile tests that, the nanocomposite with 1 wt% CNC and rGO showed maximum tensile strength compared with PLA and its nanocomposites. Moreover, the nanocomposite with 1 wt% CNC and rGO was also having maximum thermal stability. From cytotoxicity evaluation, it is observed that all the nanocomposites are nontoxic and cytocompatible to HEK293 cells. In addition to this, the nanocomposite with q‐CNC showed enhanced barrier properties compared with PLA and PLA/CNC/rGO nanocomposite. The results obtained from different characterizations showed that the incorporation of surfactant onto CNC improved the dispersion in PLA but at the same time deteriorated the PLA matrix.     

A facile and simple method for the preparation of copoly(TEAMPS/VP)/silver nanocomposites for the humidity-sensing membranes

We developed a simple method for the preparation of polyelectrolyte/silver nanocomposites, where silver nanoparticles were dispersed in a polyelectrolyte. Copoly(TEAMPS/VP)/silver (w/w=100/0, 100/1, 100/2, 100/3 and 100/4) nanocomposites were obtained by a thermal decomposition reaction of silver carbamate complex at 130 degrees C, and well-dispersed silver colloids were stabilized by copolymer of tetraethylammonium 2-acrylamido-2-methyl-1-propanesulfonate (TEAMPS) and N-vinylpyrrolidone (VP). A dark brown solution in its UV-vis absorption spectrum showed surface plasmon resonance absorption bands at 420 nm in solution. The silver precursor and the resulting polyelectrolyte/Ag nanocomposite was characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), infrared (IR), transmission electron microscopy (TEM). In addition the humidity-sensing properties using copoly(TEAMPS/VP)/Ag nanocomposite films were examined.     

New route for removal of Cu(II) using fabricated nanocomposite based on cationic surfactant/Ag-nanoparticles/silica gel

Generally, the treated wastewater must at least achieve the minimum safety standards for the purpose of the treatment process. The main target of this work is the combination of the features of surfactants, nanoparticles, and silica gel in one system for Cu(II) removal from the aqueous solution. To achieve this goal, the attempt would be made by the fabrication of nanocomposite based on 4-amino-N-tetradecyl pyridinium bromide (C14) coated silver nanoparticles and silica gel. The fabricated nanocomposite (C14-Ag-SG) was characterized using different techniques such as FTIR, XRD, XRF, SEM, and TEM. We examined the adsorption of Cu(II) ions onto the fabricated nanocomposite using batch adsorption. The effect of the contact time, pH of the solution, and mass of the adsorbent on the efficiency of adsorption was evaluated. The adsorption capacity of Cu(II) increased by increasing of the contact time with a neutral pH. The maximum removal of Cu(II) ions (98.57 %) was found using 0.4 g of the (C14-Ag-SG) nanocomposite. The fabricated nanocomposite showed high adsorption efficiency which clarifies the effect of the surfactant compound (C14) and silver nanoparticles in improving the adsorption efficiency. The results in this work suggest that the fabricated nanocomposite has high efficiency in the removal of Cu(II).     

Investigation of Structural,Rheological and Thermal Properties of PMMA/ONi-Al LDH Nanocomposites Synthesized via Solvent Blending Method: Effect of LDH Loading

This article addresses the synthesis of organically tailored Ni-Al layered double hydroxide(ONi-Al LDH) and its use in the fabrication of exfoliated poly(methyl methacrylate)(PMMA) nanocomposites. The pristine Ni-Al LDH was initially synthesized by co-precipitation method and subsequently modified using sodium dodecyl sulfate to obtain ONi-Al LDH. Nanocomposites of PMMA containing various amounts of modified Ni-Al LDH(3 wt%?7 wt%) were synthesized via solvent blending method to investigate the influence of LDH content on the properties of PMMA matrix. Several characterization methods such as X-ray diffraction(XRD), transmission electron microscopy(TEM), Fourier transform infrared spectroscopy(FTIR), rheological analysis, differential scanning calorimetry(DSC) and thermo gravimetric analysis(TGA), were employed to examine the structural, viscoelastic and thermal properties of PMMA/OLDH nanocomposites. The results of XRD and TEM examination confirm the formation of partially exfoliated PMMA/OLDH nanocomposites. The FTIR results elucidate that the characteristic bands for both pure PMMA and modified LDH are present in the spectra of PMMA/OLDH nanocomposites. Rheological analyses were carried out to examine the adhesion between polymer matrix and fillers present in the nanocomposite sample. The TGA data indicate that the PMMA nanocomposites exhibit higher thermal stability when compared to pure PMMA. The thermal decomposition temperature of PMMA/OLDH nanocomposites increases by 28 K compared to that of pure PMMA at 15% weight loss as a point of reference. In comparison with pure PMMA, the PMMA nanocomposite containing 7 wt% LDH demonstrates improved glass transition temperature(Tg) of around 3 K. The activation energy(Ea), reaction orders(n) and reaction mechanism of thermal degradation of PMMA/OLDH nanocomposites were evaluated using different kinetic models. Water uptake capacity of the PMMA/OLDH nanocomposites is less than that of the pure PMMA.     

The transparency and mechanical properties of cellulose acetate nanocomposites using cellulose nanowhiskers as fillers

Cellulose nanowhiskers (CNWs) were chemically modified by acetylating to obtain acetylated cellulose nanowhiskers (ACNWs) which could be well dispersed in acetone. The chemical modification was limited only on the surface of CNWs which was confirmed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Surface substitution degree of ACNWs was evaluated to be 0.45 through X-ray photoelectron spectroscopy (XPS). Fully bioresource-based nanocomposite films were manufactured by incorporation of ACNWs into cellulose acetate (CA) using a casting/evaporation technique. Scanning electron microscope (SEM) demonstrated that ACNWs dispersed well in the CA matrix, which resulted in high transparency of all CA nanocomposites. The tensile strength, Young’s modulus and strain at break of all CA nanocomposites exhibited simultaneous increase in comparison with neat CA matrix. At the content of 4.5 wt% ACNWs, the tensile strength, Young’s modulus and strain at break of the CA nanocomposite film were increased by 9, 39, and 44 % respectively.     

Synthesis and characterization of silver polymer nanocomposites of 1-vinyl-1,2,4-triazole with acrylonitrile

Novel organic-inorganic nanocomposites were synthesized by chemical reduction of silver ions from silver acetate in DMSO and DMF solutions in the presence of the stabilizing copolymer of 1-vinyl-1,2,4-triazole-acrylonitrile. The solvents DMSO and DMF can act as efficient reducing agents for silver ions, which makes it possible to carry out the reaction under mild conditions and simplify procedures of nanocomposite isolation. The structure and properties of the starting copolymer and related nanocomposites were characterized by UV, IR, and ¹H and ¹³C NMR spectroscopy, as well as transmission electron microscopy and thermogravimetry. The prepared polymer nanocomposites contain 6.8–7.2% silver in the form of nanoparticles with a size of 2–20 nm uniformly dispersed in the polymer matrix. The nanocomposites are readily soluble in DMSO and DMF and do not decompose on heating to 260 °C.     

Nanoflower-like composites of ZnO/SiO2 synthesized using bamboo leaves ash as reusable photocatalyst

In this study, the synthesis of ZnO/SiO₂ nanocomposites using bamboo leaf ash (BLA) and tested their photocatalytic activity for rhodamine B decolorization have been conducted. The nanocomposites were prepared by the sol–gel reaction of zinc acetate dihydrate, which was used as a zinc oxide precursor, with silica gel obtained from the caustic extraction of BLA. The effect of the Zn content (5, 10, and 20 wt%) on the physicochemical characteristics and photocatalytic activity of the nanocomposites was investigated. The results of X-ray diffraction, scanning electron microscopy, gas sorption, and transmission electron microscopy characterization confirmed the mesoporous structure of the composites containing nanoflower-like ZnO (wurtzite) nanoparticles of 10–30 nm in size dispersed on the silica support. Further, the nanocomposites were confirmed to be composed of ZnO/SiO₂ by X-ray photoelectron spectroscopy analysis. Meanwhile, diffuse-reflectance UV–visible spectrophotometry analysis of the nanocomposites revealed band gap energies of 3.38–3.39 eV. Of the tested nanocomposites, that containing 10 wt% Zn exhibited the highest decolorization efficiency (99%) and fastest decolorization rate. In addition, the degradation efficiencies were not reduced significantly after five repeated runs, demonstrating the reusability of the nanocomposite catalysts. Therefore, the ZnO/SiO₂ nanocomposite obtained from BLA is a promising reusable photocatalyst for the degradation of dye-polluted water.     

聚碳酸1,2-丙二酯/蒙脱土复合材料的制备与性能

利用阳离子交换法,以十六烷基三甲基溴化铵(HTAB)改性钠基蒙脱土制备了有机改性蒙脱土(OMMT),OMMT的层间距达到了2nm,比普通的钠基蒙脱土增加了0.74nm.采用熔融插层法制备了插层-絮凝型PPC/OMMT复合材料,当复合材料中OMMT含量为5wt%时,复合材料的杨氏模量较纯PPC树脂大幅度提高了61.8%,同时玻璃化温度(Tg)提高了2.4℃,热分解温度提高了32.3℃.因此,OMMT对大幅度提高PPC的杨氏模量具有很大的潜力.