香蕉纤维素-壳聚糖/聚丙烯酰胺双网络水凝胶的制备及吸附性能

纤维素、壳聚糖等天然多糖形成的水凝胶力学性能较弱,在应用中受到限制。该文利用香蕉纤维素-壳聚糖为第一层刚性网络,以聚丙烯酰胺为第二层柔性网络,通过"一锅法"制备了香蕉纤维素-壳聚糖/聚丙烯酰胺(cellulosechitosan/polyacrylamide, Ce-Cs/PAAM)双网络水凝胶,并采用傅里叶红外光谱(Fourier transform infrared spectroscopy,FTIR)、扫描电子显微镜(scanning electron microscope,SEM)、X射线衍射(X-ray diffractometer,XRD)等对双网络水凝胶结构进行了表征,并分析其力学性能、溶胀性能和吸附性能。结果表明,Ce-Cs/PAAM水凝胶是一种三维多孔、双网络状结构,具有优良的机械强度和韧性,在90%的压缩应变下,其最大压缩应力可以达到60 MPa;水中的溶胀度为9.56 mg/mg,在pH值为12的溶液中溶胀度为15.34 mg/mg;Ce-Cs/PAAM双网络水凝胶吸附Cu2+试验结果表明,在Cu2+的初始浓度为350 mg/L、pH值为5.5、吸附时间为90 min时,最大吸附量为312.4 mg/g。该文制备的CeCs/PAAM双网络水凝胶方法简单、力学性能、吸附性能优良,在重金属离子吸附领域具有一定的应用前景。     

pH敏感γ-聚谷氨酸/聚乙烯醇水凝胶的溶胀动力学

为了获得具有较好的持水性、生物相容性且没有细胞毒性的水凝胶,该文在不经过任何化学处理的条件下,将γ-聚谷氨酸(γ-polyglutamic acid,γ-PGA)与聚乙烯醇(polyvinyl alcohol,PVA)以3∶7,4∶6,5∶5,6∶4,7∶3的质量配比进行反应,制得pH敏感型水凝胶。对制得的水凝胶进行性能和结构表征,研究不同单体配比的水凝胶在不同p H值溶液(pH值分别为4.0,7.4,9.0)中的溶胀动力学,同时对制备的水凝胶进行了药物缓释性能初步研究。结果表明,γ-聚谷氨酸/聚乙烯醇水凝胶具备pH敏感性,溶胀度随着γ-聚谷氨酸量的增加而减小,保水率及热稳定性均随着γ-聚谷氨酸量的增加而升高。溶胀性能研究表明不同pH值的溶液媒介对水凝胶的初始扩散行为没有影响,都属于non-Fickian扩散模式,而且不同水凝胶样品在不同pH值环境中的溶胀速率的变化趋势类似,说明了在γ-PGA/PVA水凝胶的溶胀初期,水分子的扩散速率与网络大分子的松弛速率相当。不同配比的水凝胶在相同pH值环境中,水的扩散系数随着水凝胶的溶胀速率的增大而增大,且溶胀速率值又会随着PVA含量的增加而增大。药物缓释研究显示Gel3/7、Gel4/6、Gel5/5、Gel6/4、Gel7/3的包埋率分别为79.87%、75.75%、74.00%、73.50%和70.25%,说明5组水凝胶样品包埋效果较为理想,p H值的变化对5组水凝胶样品的释放性能的影响是一致的,均在p H值为7.4的缓冲溶液中药物释放较快,在p H值为1.2的缓冲溶液中释放较为平缓,释放周期加长;随着γ-PGA含量的增加,PVA含量的减少,药物的释放速率也随之减小,最终的平衡释药百分数变小,释药周期加长。研究结果为γ-聚谷氨酸/聚乙烯醇水凝胶材料在生物技术、医学以及工业领域的应用提供参考。     

香蕉假茎制备抗菌敷料的性能分析

为探究香蕉假茎制备为抗菌敷料的可行性,该研究以香蕉假茎为原料,提取香蕉纤维素,经超声粉碎获得香蕉纳米纤维素。经冷冻干燥制成5种浓度的香蕉纳米纤维素气凝胶敷料,探讨气凝胶敷料的性能。结果表明,当香蕉纳米纤维素悬浮液浓度为10 g/L时,所制备气凝胶敷料的溶胀率为3 080%,保水率为1 590%,水蒸汽透过率为810 g/m2·24h,有利于吸收伤口处的组织液和维持湿度平衡。在抗菌性的测试中,所制备的气凝胶敷料对大肠杆菌和金黄色葡萄球菌有抑制作用。研究表明香蕉假茎在生物医学方面的应用具有潜力。     

PAAM-atta复合保水剂对土壤持水性及其物理性能的影响

以丙烯酸、丙烯酰胺和凹凸棒土为原料,合成了有机无机复合保水剂(PAAM—atta)．与丙烯酸和丙烯酰胺聚合保水剂(PAAM)作对比,在室外考察了复合保水剂与纯有机保水剂对土壤物理性质的影响。结果表明．在土壤含水量、pH值、电导率、团粒结构、土壤容重和土壤孔隙度等土壤物理化学性能方面,PAAM—atta复合保水剂的改善效果较纯有机类保水剂明显。     

水溶性合成高分子对磷在土壤中有效性的影响

通过恒温培养试验研究了水溶性高分子材料聚乙烯醇、聚乙二醇和聚丙烯酰胺对P肥(Ca(H2PO4)2)在土壤中有效性的影响.结果表明:水溶性高分子材料改变了P在土壤中的吸附过程.添加聚乙烯醇和聚乙二醇的土壤pH和水溶性P含量随培养时间增加而降低;前者的土壤Olsen P含量随培养时间增加先降低后升高,后者的土壤Olsen P含量则较为恒定,为P 52mg/kg.添加聚丙烯酰胺的土壤水溶性P和Olsen P含量均随培养时间增加而增加,至培养60天时,水溶性P和Olsen P含量分别为P 0.62、60.01 mg/kg;pH变化不显著,约为4.74.     

薰衣草精油改善壳聚糖基食品包装膜的应用品质

为改善现有壳聚糖基食品包装膜的机械性能和防水性能,该文使用浇铸-蒸发-碱浸法制备了添加薰衣草精油的壳聚糖基复合膜。采用红外光谱、X射线衍射对膜进行了表征,并分析了薰衣草精油添加量对膜的厚度、机械性质、可挥发物质量分数、接触角、水溶性、溶胀性等性质的影响。结果表明:薰衣草精油成分占据了壳聚糖骨架中的部分官能团的位置,降低了壳聚糖分子中共价键的振动强度,同时膜中可以与水形成亲水键的自由H基团减少,膜的含水量降低。薰衣草精油的添加,增大了膜中壳聚糖乙酸盐的含量。膜的厚度和薰衣草精油添加量并不成线性关系,所得膜的厚度范围为(20.60±0.34)~(23.35±0.65)μm。随着薰衣草精油添加量的增加,膜的拉伸强度和断裂伸长率的变化趋势基本相同。当薰衣草精油添加量为8%时,拉伸强度和断裂伸长率都达到最大值,分别为(123.44±0.33)MPa和3.74%±0.02%。与壳聚糖膜相比,薰衣草精油/壳聚糖复合膜的的可挥发物质量分数较低,薰衣草精油添加量为2%时,可挥发物质量分数最低,为8.98%±0.05%。薰衣草精油的添加,增大了膜的溶解性,但膜在水中的溶解度均不大于(1.21±0.04)mg/100 g,属于难溶物质范畴。膜的接触角和溶胀指数都随薰衣草精油添加量的增加而减小,即当薰衣草精油添加量为10%时,膜的接触角和溶胀指数都达到最大值,分别为80.73°±0.32°和0.62±0.01。薰衣草精油的加入改善了由浇铸-蒸发-碱浸法制备的CS基复合膜的机械性质和物理性质。研究结果为薰衣草精油/壳聚糖复合膜的生产和应用提供了技术依据。     

秸秆制备拟羧甲基壳聚糖的吸水保水性能研究

评价了用秸秆粉经磺化及甘氨酸钙取代新工艺得到的拟羧甲基壳聚糖混合物（6-氨基乙酸取代的纤维素、半纤维素、木质素混合产物）吸水及保水性能,对其在室外土壤中的吸水保水性能研究表明：拟羧甲基壳聚糖混合物无论是吸湿率还是保湿率都优于天然壳聚糖原料合成的羧甲基壳聚糖产品;特别是拟羧甲基壳聚糖混合物与纤维素硫酸单酯1∶1复配物具有更好的吸湿效果,其在土壤中的最大饱和吸水量甚至优于聚丙烯酰胺,达到了35.5 g/g,并具有显著提高土壤含水量、有机质、机械稳定的团聚体含量,降低土壤容重的土壤调理作用;这一通过秸秆半合成的拟羧甲基壳聚糖混合物具有原料易得,生产工艺简单,生产成本低,使用性能优异的性价比优势,具有开发潜力。     

壳聚糖活性污泥复合吸附剂在含铬废水处理中的应用

为了解壳聚糖活性污泥在废水处理中的吸附性能,提高其吸附重金属离子的应用能力,采用壳聚糖包埋固定活性污泥,制备了壳聚糖活性污泥复合吸附剂,考察了发泡剂量、固化液浓度、交联剂浓度对吸附能力的影响。结果表明:不同固化液浓度、发泡剂量、交联剂浓度对壳聚糖活性污泥在含铬废水处理中的吸附能力均不同。其中2.0g/L氢氧化钠(NaOH)固化液、质量百分比为10%的NH_4HCO_3为发泡剂、体积分数为2.5%的环氧氯丙烷(ECH)作交联剂处理Cr~(6+)浓度为10mg/L的铬废水时,效果最佳。该复合吸附剂的制备研究一方面为污泥的资源化利用、变废为宝探索新的途径,另一方面也为污水的处理提供新的方法。     

新型碱性肥料治酸改土降镉的效果和机理

通过大田试验和模拟实验,研究碱性肥料治酸改土的效果、土壤pH对Cd吸附解吸热力学性能的影响,为碱性肥料治理土壤酸化和降低土壤Cd污染提供理论依据。结果表明:碱性肥料能明显提高大田土壤pH、显著降低土壤有效镉含量,明显遏制土壤酸化和土壤镉污染。施用碱性肥料是提高土壤pH和降低土壤有效镉含量的有效措施。当土壤Cd含量小于等于60mg·L^-1时,pH从5增加到9时几乎不影响Cd的吸附强度(在15.77 mg·kg^-1/(mg·L^-1)～16.67 mg·kg^-1/(mg·L^-1)之间);而当Cd含量大于60 mg·L^-1,Cd的吸附强度随pH的升高而明显增大,但吸附率随浓度的增大而减少。土壤Cd含量相等时,pH越高土壤Cd的吸附量及吸附率越大。土壤Cd的等温吸附曲线适于用Freundlich方程拟合和定量描述。土壤吸附Cd是自发反应过程,表现为Cd的吸附自由能(ΔG°)为负。同一pH下,ΔG°随着土壤Cd含量的增大而增大;ΔG°随着土壤溶液pH的升高而减小。碱性...     

壳聚糖-胰蛋白酶抑制剂复合可食性膜的制备及抗黄曲霉活性

为探索新型生物膜材料的制备方法及抗黄曲霉活性,以壳聚糖和大豆胰蛋白酶抑制剂(TI)提取物为原料,甘油为增塑剂,利用溶液共混流延法制备壳聚糖-TI-甘油复合可食性膜,测试其厚度、表观结构、力学性质、透光率、水蒸气透过率及抗黄曲霉侵染活性。结果表明,当壳聚糖浓度为18mg/mL、TI浓度2mg/mL、甘油浓度12mg/mL和干燥温度45℃时,制备复合膜具有优良抗黄曲霉活性,且综合理化性能最佳。制备壳聚糖-TI-甘油复合膜液涂膜于花生上,接种黄曲霉培养后发现,复合膜对于黄曲霉侵染具有较强的抵抗和抑制作用。     

Evaluation of Iron(III)-Coordinated Amino-Functionalized Poly(Glycidyl Methacrylate)-Grafted Cellulose for Arsenic(V) Adsorption from Aqueous Solutions

This study evaluated the effectiveness of a novel adsorbent (Fe(III)-AM-PGMACell), Iron(III)-coordinated amino-functionalized poly(glycidyl methacrylate)-grafted cellulose for the adsorption of arsenic(V) from aqueous solutions. The Fe(III)-AM-PGMACell was prepared through graft copolymerization of glycidyl methacrylate (GMA) onto cellulose (Cell) in the presence of N,N??-methylenebisacrylamide (MBA) as a cross linker using benzoyl peroxide initiator, followed by treatment with ethylenediamine and ferric chloride in the presence of HCl. Batch experiments were performed to evaluate the adsorption efficiency of Fe(III)-AM-PGMACell towards As(V) ions. The contact time to attain equilibrium and the optimum pH were 90?min and 6.0, respectively. More than 99.0% adsorption was achieved from an initial concentration of 25.0?mg/L. A two-step pseudo-first-order kinetic model agreed well with the dynamic behavior for the adsorption process. Equilibrium data fitted well with Sips isotherm model with maximum adsorption capacity of 78.8?mg/g at 30??C. The desorption of As(V) was achieved over 98.0% with 0.1?M NaCl solution.     

Xylan-rich hemicelluloses-graft-acrylic acid ionic hydrogels with rapid responses to pH, salt, and organic solvents

Exploitation of biomaterials derived from renewable resources is an important approach to address environmental and resource problems in the world today. In this paper, novel ionic hydrogels based on xylan-rich hemicelluloses were prepared by free radical graft copolymerization of acrylic acid (AA) and xylan-rich hemicelluloses (XH) by using N,N-methylene-bis(acrylamide) (MBA) as cross-linker and ammonium persulfate/N,N,N',N'-tetramethylethylenediamine (APS/TMEDA) as redox initiator system. The network characteristics of the ionic hydrogels were investigated by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), as well as by determination of mechanical properties, swelling, and stimuli responses to pH, salts, and organic solvents. The results showed that an increase in the MBA/XH or AA/XH ratio resulted in higher cross-linking density of the network and thus decreased the swelling ratio. Expansion of the network hydrogels took place at high pH, whereas shrinkage occurred at low pH or in salt solutions as well as in organic solvents. The ionic hydrogels had high water adsorption capacity and showed rapid and multiple responses to pH, ions, and organic solvents, which may allow their use in several areas such as adsorption, separation, and drug release systems.     

Highly effective adsorption of heavy metal ions from aqueous solutions by macroporous xylan-rich hemicelluloses-based hydrogel

Xylan-rich hemicelluloses-based hydrogel was developed as a novel porous bioadsorbent by graft co-polymerization of acrylic acid (AA) and xylan-rich hemicelluloses for adsorption of heavy metal ions (Pd(2+), Cd(2+), and Zn(2+)) from aqueous solutions. The chemical structure, the interaction between the hydrogel and metal ions, and the porous structure of xylan-rich hemicelluloses-g-AA hydrogel were revealed by Fourier transform infrared spectroscopy and scanning electron microscopy. The effects of AA and cross-linker dosage, pH value, contacting time, and initial concentration of metal ion on the adsorption capacity were studied. The adsorption equilibrium time was about 60 min from the adsorption kinetics study. The maximum adsorption capacities of Pd(2+), Cd(2+), and Zn(2+) were 859, 495, and 274 mg/g, respectively. Furthermore, xylan-rich hemicelluloses-g-AA hydrogel also exhibited highly efficient regeneration and metal ion recovery efficiency and can be reused without noticeable loss of adsorption capacity for Pd(2+), Cd(2+), and Zn(2+) after quite a number of repeated adsorption/desorption cycles.     

磁性壳聚糖微球吸附苹果汁有机酸的动力学及热力学特性

为充分利用中国丰富的苹果资源,开发多品类的苹果深加工产品,以磁性壳聚糖微球为吸附剂,通过磁分离技术,吸附获得苹果汁中的天然有机酸,并对其吸附过程进行研究。利用Lagergren准一级动力学方程、准二级动力学方程、Elovich方程及内扩散方程对吸附反应动力学过程进行拟合;利用Langmuir等温吸附模型、Freundlich等温吸附模型及Temkin等温吸附模型对吸附等温数据进行拟合,并对其吸附反应热力学特性进行分析。通过比较线性拟合方程的决定系数,发现磁性壳聚糖微球吸附苹果汁中有机酸的动力学过程更加符合Lagergren准二级动力学模型,吸附温度越高,吸附速率常数和初始吸附速率越大,但平衡吸附量越低。等温吸附过程更加符合Langmuir等温吸附模型,表明该吸附过程更趋向于单分子层的化学吸附。298 K时,有机酸的饱和吸附量可达到188.679 2 mg/g,表明磁性壳聚糖微球是苹果汁中有机酸的1种高效吸附剂。热力学参数ΔG°0,ΔH°0,ΔS°0,表明磁性壳聚糖微球对苹果汁有机酸的吸附过程为熵增加的可自发进行的放热过程。动力学及热力学结果为磁性壳聚糖微球吸附苹果汁有机酸的研究提供了理论基础与技术支持。     

Preparation and characterization of novel micro- and nanocomposite hydrogels containing cellulosic fibrils

The main objective of this article was to report a simple, fast, and low cost strategy for the synthesis of micro- and nanocomposites by adding cellulose nanofibers, obtained by acid hydrolysis, and added to hydrogels as reinforcing agents. Specifically, when cellulose nanofibers were added to hydrogels, morphologic analyses showed significant decreases in pore size and formation of three-dimensional well-oriented porous microstructure. It was also observed that cellulose nanoparticles improved the mechanical and structural network properties without negatively impacting their thermal and hydrophilic properties. The value of maximum compressive stress was 2.1 kPa for the PAAm-MC, and it increased to 4.4 kPa when the cellulose nanofiber was incorporated into the hydrogel. By investigation of XRD patterns, it was found that the incorporation of cellulose nanofiber affected the crystallinity of PAAm-MC hydrogels, thus contributing to improvements in mechanical, structural, and hydrophilic properties of the PAAm-MC hydrogels.     

Immobilization of Calcined Layered Double Hydroxide into Alginate Hydrogel Beads for PNP and PAP Removal: Kinetics,Isotherms, Thermodynamics,and Mechanism

The calcined layered double hydroxide (CLDH)-alginate hydrogel beads were synthesized by embedding CLDH into alginate hydrogel beads. The beads were used to remove p-nitrophenol (PNP) and p-aminophenol (PAP) from aqueous solution. The structure and composition of CLDH-alginate hydrogel beads were characterized by scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), elemental mapping, transmission electron microscope (TEM), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, BET, and X-ray photoelectron spectroscopy (XPS). The adsorption kinetic, isothermal, thermodynamic properties and adsorption mechanism of PNP and PAP on CLDH-alginate hydrogel beads were studied. The results demonstrated that the adsorption kinetic data fitted the pseudo-second-order model well with the correlation coefficients (R²) of 0.9975 and 0.9995 for PNP and PAP, respectively. The isothermal data followed the Freundlich equation, and the values of R² for PNP and PAP were 0.9728 and 0.9946, respectively. The adsorption processes were feasible, spontaneous, and endothermic. The adsorption mechanism was predominated by anionic exchange and hydrogen bonding for PNP and hydrogen bonding for PAP, which was evidenced by the results of adsorption experiments, characterization of FTIR and XPS, and theoretical calculation. Furthermore, the CLDH-alginate hydrogel beads can be separated easily due to their larger particle size. This will provide convenience in practice application.     

微波辅助合成壳聚糖基高吸水性树脂

在水溶性引发剂过硫酸钾(KDS)的引发下,用微波辐照使丙烯酸在壳聚糖分子链上接枝聚合,并加入N,N’-亚甲基双丙烯酰胺进行适度交联,制备高吸水性树脂。利用FT-IR对产物结构进行定性表征,结果表明,丙烯酸在壳聚糖的分子链上发生了接枝聚合反应。研究了反应条件对产物吸液性能的影响,并通过正交试验对工艺条件进行优化。在最佳条件下合成产物的吸水倍率为815.0g/g,吸生理盐水倍率为72.2g/g,吸人工尿液倍率为67.5g/g。在微波作用下产物合成速率是传统方法的数十倍,吸液性能明显高于后者,且操作条件容易控制,后处理步骤明显简化,无污染,是一种高效的清洁生产工艺。     

辐射接枝共聚物XG-g-NVP溶胀性能及其对苯酚吸附特性的研究

采用共辐射接枝法制备黄原胶-N-乙烯基吡咯烷酮接枝共聚物(XG-g-NVP),研究其溶胀性能及对苯酚的吸附性能.研究表明,XG-g-NVP在接枝率为623%时溶胀性能和吸附苯酚的能力最强,分别为62.1和0.76g/g.红外分析显示,XG-g-NVP与苯酚通过氢键相结合.XG-g-NVP对苯酚吸附符合Freundlic...