基于微生物和纳米TiO2的双负载核壳水凝胶的制备及性能

设计了能同时利用微生物和光催化剂,分步逐级降解亚甲基蓝(MB)的多功能双负载核壳水凝胶,核为聚乙烯醇和羟乙基纤维素包覆酵母菌,壳为海藻酸钠和钙离子负载纳米TiO2.SEM结果表明,核壳结构清晰可辨;显微镜照片和荧光标记照片证明了核中酵母菌的存在;XRD结果证明了壳中纳米TiO2的负载;FTIR、XPS结果证实了核壳结构的分子间存在着相互作用力.考察了在TiO2和酵母菌不同用量下制备的水凝胶对MB的分步降解效果,壳中纳米TiO2用量越高,水凝胶对MB的降解率越大,最高可达96.65％;而随着酵母菌用量的增加,水凝胶对MB的降解率先增大后减小.在使用4次后,水凝胶对MB的降解率仍有68.97％.     

玉米淀粉/羧甲基纤维素生物复合凝胶的制备及吸附行为研究

以玉米淀粉与羧甲基纤维素（CMC）为骨架，以丙烯酸（AA）、丙烯酰胺（AM）、2-丙烯酰胺基-2-甲基丙磺酸（AMPS）为单体制备复合凝胶，对复合凝胶材料进行表征。以亚甲基蓝（MB）为吸附质，考察复合凝胶吸附剂对阳离子染料吸附过程的动力学和热力学行为，分析阳离子强度、水体pH值、染料初始质量浓度等对吸附剂吸附性能的影响。结果表明：玉米淀粉-CMC-g-AA-AM-AMPS凝胶是一种表面多孔的吸附材料，其比表面积为24.939 7 m2/g，平均吸附孔径为8.668 2 nm。凝胶对MB的吸附过程与准二级动力学模型和Langmuir模型拟合较好，属于单分子层的化学吸附。阳离子对凝胶吸附MB有明显抑制作用，抑制效果为Al3+>Ca2+>Na+。随着离子强度的增加，抑制作用越明显。在投加量为0.1 g、温度为298 K、pH值为11.0、MB初始质量浓度为2 000 mg/L条件下，吸附剂最大吸附量达到1 938.82 mg/g、去除率为96.94%，能有效去除MB。     

基于微生物和纳米TiO2的双负载 核壳水凝胶的制备和性能

摘要：设计了能同时利用微生物和光催化剂，分步逐级降解有机污染物的多功能双负载核壳水凝胶，核为聚乙烯醇（PVA）和羟乙基纤维素（HEC）包覆酵母菌（YE），壳为海藻酸钠（SA）和钙离子（Ca2+）负载纳米二氧化钛（TiO2 NPs）。采用SEM观察形貌可知，核壳结构清晰可辩，显微镜照片和荧光标记照片证明了核中YE的存在，XRD分析结果证明了壳中TiO2 NPs的负载，同时FTIR、XPS验证了核壳结构的分子间存在着相互作用力。并且在不同负载量下，研究了核壳水凝胶对亚甲基蓝（MB）染料去除的分步降解效果，壳中TiO2 NPs负载量越高，对MB的降解最高，可达96.65%； YE负载量的增加而MB的降解率先增大后减小，最高可达92.15%。在循环降解4次后，对MB染料的降解率仍有68.97%。本研究为分步多次降解多种有机污染物，提供并拓展了研究思路和新方法。     

二氧化硅气凝胶的孔结构及液相吸附行为

通过溶胶-凝胶、CO2超临界干燥工艺制备了高比表面积的块状SiO2气凝胶.改变液态CO2萃取循环压力,得到不同孔径和孔径分布的SiO2气凝胶.对样品进行了液氮物理吸附测定,并采用密度函数理论,Alpha-s(αs)和Dubinin-Radushkevich方法对材料的表面结构进行了分析,通过等温吸附实验研究了样品对亚甲基蓝(methylene blue,MB)的吸附性能.结果表明:升高循环压力,可使Si02气凝胶的平均孔径变小、孔径分布变窄;微孔孔容和中孔孔容随循环压力升高先增大后减小,在6.5 MPa时达到最大.对吸附热力学过程的研究表明,Langmuir等温吸附方程能够很好地描述SiO2气凝胶对MB的吸附过程,而吸附动力学研究表明该吸附过程符合准二级动力学模型.     

羟甲基化木质素/纤维素气凝胶粒子的制备、表征及吸附性能

以羟甲基化木质素和纤维素为原料，NaOH/尿素水溶液为溶解体系，采用冷冻干燥法制备羟甲基化木质素/纤维素气凝胶粒子。采用扫描电子显微镜（SEM）、傅里叶变换红外光谱（FT-IR）仪、X射线衍射（XRD）仪、比表面积及孔径分析仪等对其结构进行了表征。研究结果表明：羟甲基化木质素分子通过氢键作用附着在纤维素骨架上，气凝胶内部仍保持三维网状结构，羟甲基化木质素的引入使得气凝胶表面出现明显收缩，网状结构的致密度随着羟甲基化木质素用量提高而逐渐降低；同时气凝胶粒子具有纤维素Ⅱ型红外吸收峰和XRD衍射峰；粒子表现出Ⅱ型吸附/脱附等温线，孔径均在15 nm以下，且随着羟甲基化木质素用量不断提高，比表面积、孔容均有所减小，HKL-4的比表面积为105.3m²/g，孔容为0.336 6cm³/g，孔径为13.67nm。吸附性能分析表明在25℃下吸附5 h，HKL-4气凝胶粒子对金胺O、亚甲基蓝和罗丹明B的吸附量分别为33.06、96.06和43.26mg/g，对亚甲基蓝的饱和吸附量可达208.7 mg/g，吸附过程更符合Langmuir等温吸附模型，主要为单分子层吸附。     

聚乙烯醇-壳聚糖互穿网络水凝胶的合成与性能研究

以聚乙烯醇和壳聚糖为原料合成了聚乙烯醇-壳聚糖互穿网络水凝胶,研究了聚乙烯醇与壳聚糖质量比、溶剂醋酸溶液体积、交联剂戊二醛浓度等对聚乙烯醇-壳聚糖互穿网络水凝胶溶胀性能和硬度的影响,得到了最佳合成条件.随着聚乙烯醇与壳聚糖质量比、交联剂戊二醛浓度的增大及溶剂醋酸溶液体积减小,凝胶溶胀度减小而硬度增大.聚乙烯醇-壳聚糖凝胶具有良好的生物相容性.     

水合纤维素微球对结晶紫模拟废水的吸附研究

制备了水合纤维素微球,比较了纤维素改性前后对结晶紫的吸附性能。结果表明,改性后的水合纤维素微球比表面积增大,吸附位点增多,对结晶紫吸附能力明显提高。考察了不同因素对纤维素和水合纤维素微球吸附结晶紫性能的影响。确定吸附最佳时间为180 min;随着吸附剂投加量的增加,吸附率增大,吸附量减小;随着结晶紫初始浓度增大,吸附率减小,qe增大。适当盐离子浓度对水合纤维素微球吸附结晶紫有一定的促进作用。p H中性条件下就可达到较好的吸附效果。水合纤维素符合Langmuir吸附等温式和Freundlich吸附等温式。     

水合纤维素微球对结晶紫模拟废水的吸附研究

制备了水合纤维素微球,比较了纤维素改性前后对结晶紫的吸附性能。结果表明,改性后的水合纤维素微球比表面积增大,吸附位点增多,对结晶紫吸附能力明显提高。考察了不同因素对纤维素和水合纤维素微球吸附结晶紫性能的影响。确定吸附最佳时间为180 min;随着吸附剂投加量的增加,吸附率增大,吸附量减小;随着结晶紫初始浓度增大,吸附率减小,qe增大。适当盐离子浓度对水合纤维素微球吸附结晶紫有一定的促进作用。p H中性条件下就可达到较好的吸附效果。水合纤维素符合Langmuir吸附等温式和Freundlich吸附等温式。     

氯霉素在活性炭上的吸附平衡与动力学

为去除水体中残留的氯霉素,采用生物相容性佳的活性炭作吸附剂,测定了25,30,35℃下氯霉素在自制活性炭上的吸附平衡与动力学,并与商用竹炭作对比。结果表明高比表面积活性炭是去除水体中残留氯霉素的高效吸附剂,活性炭的吸附容量随着吸附剂比表面积和孔容的增大而增大,但随温度从25,30到35℃升高而减小,自制高比表面积活性炭的吸附容量达到3种市售活性炭样品吸附容量的10倍以上;Freundlich吸附等温线方程可较好地描述氯霉素在活性炭上的吸附平衡,准二级方程是用来描述氯霉素在活性炭上吸附的合适动力学模型,并通过拟合得到了其动力学参数。随着温度的升高吸附容量逐渐减小。本研究为活性炭对水体中残留氯霉素的吸附处理提供了科学依据。     

黄原胶接枝聚丙烯酸水凝胶的合成及对亚甲基蓝阳离子染料的吸附性能

以黄原胶和丙烯酸为原料,N,N'-亚甲基双丙烯酰胺为交联剂,过硫酸钾为引发剂,在水溶液中合成黄原胶接枝聚丙烯酸(XG-g-PAA)水凝胶,考察了pH值、吸附时间、阳离子染料亚甲基蓝(MB)的初始浓度等对水凝胶吸附性能的影响,研究了水凝胶对MB的等温吸附行为。结果表明,当pH值大于5.0时,XG-g-PAA水凝胶对MB有较大的吸附量;水凝胶吸附平衡时间为5 h;室温下随着MB初始浓度的增大,水凝胶对MB的吸附量较大;水凝胶对MB的吸附行为符合Freundlich吸附等温模型,其相关系数为0.985 54,吸附过程以化学吸附为主。     

Preparation and adsorption mechanism of polyvinyl alcohol/graphene oxide-sodium alginate nanocomposite hydrogel with high Pb(II) adsorption capacity

A series of polyvinyl alcohol (PVA)/graphene oxide (GO)-sodium alginate (SA) nanocomposite hydrogel beads were prepared through in situ crosslinking for Pb²⁺ removal. It was found that PVA and SA molecules were intercalated into GO layers through hydrogen bonding interactions, leading to the destruction of orderly structure of GO, while GO uniformly distributed in PVA matrix. With increasing PVA solution concentration, the hydrogel beads became more regular, a large number of polygonal pores with thin walls and open pores formed, the average pore size decreased, and the dense network structure formed. Meanwhile, the permeability of the composite hydrogel decreased, leading to the decline of Pb²⁺ adsorption capacity of the composite hydrogel. With increasing GO content, the ballability of the hydrogel beads was weakened, the pore size increased, and relatively loose network structure formed, resulting in an increase in permeability and Pb²⁺ adsorption capacity of the hydrogel, reaching up to 279.43 mg g⁻¹. Moreover, the composite hydrogel presented relatively good reusability for Pb²⁺ removal. The adsorption mechanism was explored and showed that the adsorption system of the composite hydrogel belonged to the second-order kinetic model and fitted Langmuir adsorption isotherm model for Pb²⁺ removal, which might be mono-layer chemical adsorption. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47318.     

Hydroxyethyl cellulose hydrogel modified with tannic acid as methylene blue adsorbent

This work developed an effective way to improve the methylene blue (MB) adsorption performance of cellulose-based hydrogel by modified with tannic acid (TA). HEC-co-p(AA-AM)/TA hydrogel was synthesized by grafting of acrylic acid (AA) and acrylamide (AM) onto hydroxyethyl cellulose (HEC), followed by modified with TA. Fourier transform infrared spectroscopy manifested that AA and AM were successfully grafted onto the hydrogel, and TA was immobilized in the hydrogel. Field emission scanning electron microscope demonstrated that the hydrogel after TA modification had a homogeneous pore structure. Brunauer-Emmett-Teller (BET) surface areas, total pore volume, and average pore diameters of the hydrogel are 11.821 m² g⁻¹, 0.0641 cm³ g⁻¹, and 2.538 nm, respectively. The high swelling ratio (1179.2 g g⁻¹ in deionized water) was in favor of the MB adsorption. The results of the adsorption experiments illustrated that HEC-co-p(AA/AM) hydrogel had excellent MB adsorption performance. As the pH increases, the electrostatic attraction is enhanced, and the adsorption capacity is improved. The adsorption process was more fit with pseudo-second-order kinetics, and the maximum adsorption capacity (3438.27 mg g⁻¹) was determined by Langmuir model. Thermodynamic studies suggested that the adsorption process is spontaneous, exothermic, and entropy reduction. X-ray photoelectron spectroscopy analysis confirmed that MB molecules were reacted with the oxygen atoms in hydroxyl and carboxyl groups by ion-exchange. High reusability demonstrated that the hydrogel could be a potential candidate for removal cationic dye from industrial effluents.     

Radiation-initiated chitosan-based double network hydrogel: Synthesis,characterization, and adsorption of methylene blue

A novel chitosan (CTS)-based double network Poly(2-acrylaMido-2-Methyl-1-propanesulfonic acid)/Polyacrylamide/CTS hydrogel was synthesized by irradiation initiated. Laponite RD (RD) was used as both dopant and the cross-linking agent. Then the fabricated hydrogel was applied as an efficient adsorbent to remove the methylene blue (MB) in an aqueous solution. This hydrogel has both high strength and good adsorption properties for MB. The results from Brunauer–Emmett–Teller method confirmed that the hydrogel has a large specific surface area (96 m²/g) and developed pore structure, which is available for the contact between the adsorbent and dye molecules. In the adsorption process, the RD provides plenty of negative charges as adsorption sites for MB molecules. The influence of pH, temperature, and adsorbent dose on the adsorption performance was investigated in detail. The experimental data fit well with the pseudo-second-order kinetic model and Langmuir isotherm. Besides, the mechanical strength of the hydrogel was also investigated in this work.     

GPs-PVA/MCE多功能杂化膜的制备及性能

地聚物微纳米粒子（GPs）经聚乙烯醇（PVA）修饰后,采用真空抽滤法将其组装在混合纤维素基膜（MCE）表面,得到多功能地聚物颗粒-聚乙烯醇/混合纤维素杂化膜（GPs-PVA/MCE）。本文考察了GPs的添加量对杂化膜结构和性能的影响,通过SEM、FTIR、AFM、XRD等表征杂化膜的结构。结果表明GPs添加量为0.15g时制备的杂化膜性能最佳,水通量为11293L/(m²·h·MPa)。该多功能杂化膜对不同污染物均表现出优异的去除性能：通过孔道截留作用可去除水中100%的50nm聚苯乙烯微球和99.87%的乳化油;通过吸附作用亦可去除水中100%的阳离子型染料;比原始MCE膜分别提升了528.54%、25.78%、90.96%。特别是在连续处理含油乳液时,该杂化膜使用1h后通量仅降低了21.70%,远低于MCE膜的95.70%,说明其抗污染性能得到显著提升,显示出良好的应用潜力。     

纤维素热解生物油分子尺寸分布特性

分子筛催化剂的孔径与生物油分子尺寸之间的差异造成分子筛催化剂的择形选择性。分子筛的孔径数据来自晶体结构分析,而生物油的分子尺寸数据很难获得,对生物油的分子尺寸进行估算十分必要。采用热裂解气质联用技术(Py-GC/MS)研究了纤维素热解生物油的组成成分,以Joback基团贡献法为基础计算了纤维素热解生物油各组成成分的动力学直径,分析了纤维素热解生物油的分子尺寸分布特性。结果表明,纤维素在350~600℃热解产生生物油的主要成分为脱水糖、呋喃衍生物和酮类化合物,生物油各组成成分的动力学直径主要分布在[0.500, 0.600) nm。当热解温度由350℃升至600℃时,动力学直径位于[0.550, 0.600) nm的生物油各组成成分的峰面积百分比由88.72%降至64.53%,位于[0.500, 0.550) nm的生物油各组成成分的峰面积百分比则由2.88%升至21.95%。纤维素催化裂解制备高品质液体燃料可选用ZSM-5, ZSM-11和IM-5等孔径尺寸0.500~0.600 nm的分子筛催化剂。     

国产聚乙烯醇助分散剂对悬浮法聚氯乙烯树脂颗粒特性的影响

在聚乙烯醇／羟丙基甲基纤维素复合主分散体系基础上加入聚乙烯醇助分散剂。对比研究了国内外同类型聚乙烯醇对分散体系界面张力、保胶能力和聚氯乙烯树脂颗粒形态的影响。结果发现：随着聚乙烯醇助分散剂含量增加,分散剂水溶液一三氯乙烯界面张力和保胶能力降低,聚氯乙烯树脂平均粒径和增塑剂吸收量增加,初级粒子聚集程度降低。     

马来酸酐改性聚乙烯醇对水体中Pb2+的吸附行为

通过羟基的酯化反应并采用浓硫酸进行碳化处理,制备了马来酸酐改性聚乙烯醇,通过FTIR对其化学结构进行了表征,并研究了改性聚乙烯醇对水体中Pb^2+的吸附行为及重复使用性能。研究结果表明,改性后的聚乙烯醇表面基团结构发生了变化,成功引入了大量的—COOH;另外,其结构上呈现出大量的孔洞结构和更大的比表面积,使其与金属离子具有更多吸附位点和更强的络合能力。静态吸附结果表明,在吸附时间为60 min、pH为5.0、改性聚乙烯醇用量为0.10 g的条件下,改性聚乙烯醇对Pb^2+的饱和吸附量为287.3 mg/g,符合Langmuir等温吸附模型。通过吸附-脱附实验发现,马来酸酐改性聚乙烯醇吸附Pb2+时,具有良好的重复使用性能。     

Synthesis and Characterization of Nano-Composite Alumina–Titania Ceramic Membrane for Gas Separation

A ceramic composite membrane was prepared using a commercial titania ceramic membrane coated by alumina oxide via a sol–gel technique where polyvinyl alcohol (PVA) was used as a binder. The characteristic of the membrane was analyzed in terms of the effect of PVA concentration and sintering temperature on viscosity, pore size, density, porosity and surface area of the membrane. Two vol% of PVA solution containing 4 g of PVA in 100 mL of water was adequate to achieve an appropriate porosity level to avoid cracks on the gel layer. Sol viscosity and pore size of the membrane essentially increased when the PVA concentration was increased. The density of the membrane increased as the sintering temperature increased. The porosity level however, decreased when the temperature was increased. The composite membrane was further characterized in terms of permeability of pure gas at low-temperature region (301 K) where an experimental platform has been developed to perform the permeability studies.     

氯化专用聚氯乙烯树脂颗粒特性的研究——非离子型表面活性剂和链转移剂的影响

水相悬浮法生产氯化聚氯乙烯(CPVC)时,氯化速度和氯化均匀性取决于Cl2在聚氯乙烯(PVC)颗粒中的扩散程度,因而需要有能满足氯化要求的PVC专用树脂。采用以聚乙烯醇(PVA)和羟丙基甲基纤维素(HPMC)为主的复合分散剂,考察Span系列非离子表面活性剂、链转移剂等对PVC颗粒特性的影响。实验结果表明,表面活性剂的加入使PVC树脂增塑剂吸收率、平均粒径和比表面积增大,粒径分布变窄,而表观密度下降;随着链转移剂的加入,PVC树脂增塑剂吸收率、平均粒径和表观密度都增加。     

Functionalization of polyvinyl alcohol hydrogels with graphene oxide for potential dye removal

Because of highly frozen macromolecule chains, polyvinyl alcohol (PVA) hydrogels have never been used for dye removal. This work focuses on improving the adsorption capacity of the PVA hydrogel by using amphiphilic graphene oxide to improve its macromolecular chain mobility in crystal domain and introduce new functional groups. To evaluate its effectiveness, crystal structure, swelling kinetics, and model dye methylene blue (MB) adsorption of the as‐prepared PVA hybrid hydrogels were systematically investigated. The results indicate that the hybrid PVA hydrogels have lower crystallinity and less crystal stability, demonstrating the improved macromolecular chain mobility. Moreover, improved swelling ratios of PVA/GO hydrogels also illustrate the enhanced macromolecular chain mobility. MB adsorption experiment indicates that GO introduced can result in great improvement in MB adsorption. And the adsorption process follows the second‐order kinetic model and Morris–Weber model, which is determined by the intraparticle diffusion. Furthermore, MB adsorption isotherm follows Freundlich model and the adsorption is heterogeneous. Desorption studies indicate that the interaction between PVA hydrogels and MB consists of both physisorption and chemisorption. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39872.