壳聚糖对印染废水的絮凝作用和脱色效果

壳聚糖可作为阳离子型和阴离子型絮凝剂 ,对无机化合物、极性有机化合物、蛋白质等产生絮凝作用[1] .壳聚糖无毒 ,对动、植物无害 ,用其作为絮凝剂的污泥可作肥料 .在环境保护方面具有广阔的应用前景 .本文报道直接用壳聚糖对印染厂废水处理的絮凝和脱色效果研究 .壳聚糖自制 ,广东省佛山市上朗针织漂染厂印染废水 ,上海分析仪器厂 72 2光栅分光光度计 ,可调多联搅拌器 .结果与讨论絮凝效果的测定参照美国材料与试验协会 ( ASTM)有关标准[2 ,3 ] .取印染废液 1 0 0 0 m L,快速搅拌约 1 min,降低转速至约 2 0～ 60 r/min进行慢速搅拌 ,记录…     

N,O-羧甲基壳聚糖的合成和性质研究

采用多段升温法将壳聚糖改性,合成了取代度为1.84、平均分子量为3.08×105、等电点为7.28的N,O-羧甲基壳聚糖(CMC),分别用紫外光谱、红外光谱、荧光光谱对其结构进行了表征,并对其水溶液的Zeta电位、电导率、表面张力以及水分散体系中羧甲基壳聚糖微粒的粒径分布进行了研究.结果表明, N,O-羧甲基壳聚糖具有表面活性;介质的pH值和浓度对羧甲基壳聚糖溶液的稳定性有很大的影响.     

壳聚糖与正丁醛缩合反应的研究

壳聚糖具有絮凝和螯合作用,能与许多重金属离子形成稳定的螯合物。但分子的氨基在pH值较低的水溶液中容易形成NH3 使壳聚糖溶于水而降解,导致吸附剂流失[1]。壳聚糖在吸附过程中表现出对某些金属离子的吸附性能和选择性并不能令人满意,通过改性引入螯合能力强的功能基团,吸附性     

羧甲基壳聚糖对亚铁离子的吸附

壳聚糖是由甲壳素经脱乙酰基后得到的一种天然高分子氨基多糖 ,它是金属离子的良好配体 ,其配合物在工业、农业、食品、环保、医药等方面的应用已有许多研究 [1～ 4 ] .脱乙酰基后的壳聚糖溶解性有很大改善 ,但仍只能溶于酸或酸性水溶液 ,限制了它的推广应用 .通过化学改性的羧甲基壳聚糖 ( CMCS)具有良好的水溶性、保湿性、乳化性 ,其分子中含有— OH、— NH2 、—COOH等基团 ,能有效络合金属离子 [5] .人体对壳聚糖 -亚铁络合物的吸收远远大于传统的 Fe SO4 药物 [6 ] ,壳聚糖及其衍生物与 Fe2 的络合物有可能用于治疗缺铁性贫血 …     

羧乙基壳聚糖的合成及表征

壳聚糖是甲壳素的N-脱乙酰基产物,并具有良好的螯合重金属离子、纺丝性和成膜性,且无毒副作用,广泛应用污水处理、食品、生物医用材料等领域[1-3].水溶性壳聚糖的合成及应用近年来文献报道很多[4-8].但对于水溶性羧乙基壳聚糖的合成报道较少.     

荧光探针法研究壳聚糖在水溶液中的聚集态行为

本文用两种结构类似的分子内电荷转移化合物,3-羟基-6甲基-4-N,N-二甲氨基黄酮丙酸酯(PF)和3-甲氧基-4’-N,N-二甲氨基黄酮(DMMF),作为荧光探针,研究了壳聚糖在水溶液中的聚集状态.研究结果发现,当壳聚糖浓度增大到1×10^-3 kg/L或以上时,PF在430 nm处的荧光强度有一突增现象.利用DMMF作为荧光探针,研究了它在不同壳聚糖溶液中的稳态偏振,研究发现,随着壳聚糖浓度的增大,其偏振度也明显增大.这些结果进一步证实了壳聚糖在水溶液中的聚集特性,同时也为分子内电荷转移化合物——黄酮类化合物作为荧光探针研究生物大分子在水溶液中的构象提供了有益的尝试.     

离子液体[BMim]BF4对SDS水溶液表面活性和聚集能力的促进

采用表面张力测定法和核磁共振谱等方法研究了阴离子表面活性剂十二烷基硫酸钠(SDS)在水溶性室温离子液体[BMim]BF4/水混合溶剂中的表面性质及聚集行为, 发现极少量[BMim]BF4的介入就可以显著降低SDS的临界胶束浓度, 提高体系的表面活性; 且[BMim]BF4在混合溶剂中所占的摩尔分数(x1)在一定范围内(0相似文献   

Cu~(2 )壳聚糖螯合物及壳聚糖吸附Cu~(2 )机理的XPS研究

壳聚糖能选择性地吸附Ｍｇ2 、Ｎｉ2 、Ａｌ3 、Ａｇ 、Ｐｂ2 等金属离子[1],在环境保护、水处理、贵金属精制和回收等领域有广泛的应用前景[2 ].目前对壳聚糖吸附金属离子尤其是对Ｃｕ2 吸附的研究十分活跃 ,对壳聚糖吸附了Ｃｕ2 后形成的螯合物的研究也有报道[3,4 ].Ｉｎａｋｉ等[5]认为壳聚糖吸附Ｃｕ2 的机理是通过其表面—ＮＨ2 及其邻近的—ＯＨ与Ｃｕ2 进行络合反应从而吸附了Ｃｕ2 .本文用Ｘ射线光电子能谱 (ＸＰＳ)研究了壳聚糖及吸附Ｃｕ2 后形成的Ｃｕ2 壳聚糖螯合物表面的元素组成及其结合能的变化 ,根据结合能的变…     

双亲性羧甲基壳聚糖钠盐席夫碱衍生物的合成及其性能研究

旨在以天然产物为基础,设计与合成具有表面活性和抗菌等特性的多功能高分子,拓宽天然产物应用领域.首先壳聚糖与一氯乙酸取代反应获得O-羧甲基壳聚糖钠盐,然后依次与柠檬醛、对羟基苯甲醛进行席夫碱反应,最终制得O-羧甲基壳聚糖钠盐缩柠檬醛缩对羟基苯甲醛,并通过1H-NMR和元素分析对产物的结构进行表征.通过测定终产物的表面张力(γ)、临界胶束浓度(CMC)、亲水亲油平衡值(HLB)、乳化能力和抗菌能力等对其性能进行评价,结果表明:该产物具备表面活性且其水溶液能够抑制细菌增长,具有成为功能性高分子表面活性剂的潜力.     

离子液体中壳聚糖/AMPS共聚交联微球的制备

与线性聚合物相比,交联聚合物因其复杂的结构而具有特殊的性能[1～3].壳聚糖是甲壳素的N-脱乙酰基产物,具有良好的生物相容性、无毒性和生物可降解性等特点[4],在食品、医药及水处理等领域中广泛应用[5～7].在实际应用中,经常将各种单体接枝到聚合物表面,由于单体的均聚反应影响接     

Chitosan and its hydrophobic derivatives: Preparation and aggregation in dilute aqueous solutions

This review surveys the main methods of preparing chitosan and its hydrophobic derivatives and their influence on the microstructure of polymers. The experimental data on the aggregation of these polymers in dilute aqueous solutions are summarized. Basic factors affecting aggregation are analyzed, and its general regularities are revealed. It is shown that, in the case of both chitosan and its hydrophobic derivatives, the formation of aggregates is governed by the competition of attraction of associating groups promoting aggregation and their repulsion arising from the presence of charged units and counterions hindering aggregation. Various aggregate models that were proposed for chitosan derivatives with different main-chain lengths and different contents of associating groups are discussed.     

壳聚糖不饱和羧酸盐聚集行为的研究

以半干法制备了一系列壳聚糖不饱和羧酸盐--壳聚糖水杨酸盐(a1)、壳聚糖苯甲酸盐(a2)、壳聚糖肉桂酸盐(a3)壳聚糖丙烯酸盐(a4)和壳聚糖衣康酸盐(a5).用红外光谱和紫外光谱表征了该产品的结构,以凯氏定氮法测定了羧酸的结合量.结果表明壳聚糖和不饱和羧酸盐是通过壳聚糖上的氨基和羧酸中的羧基发生了成盐反应,羧酸的结合...     

壳聚糖在稀溶液中的聚集行为

壳聚糖在稀溶液中的聚集行为;荧光探针;荧光偏振;聚集行为     

Preparation and properties of liposomes coated with <Emphasis Type="Italic">N</Emphasis>-acylated low-molecular-weight chitosan

Amphiphilic low-molecular-weight chitosan N-acylated with 3-hydroxytetradecanoic acid was synthesized. It was shown that addition of the acylated chitosan changes the surface potential and size of negatively charged liposomal particles, the magnitudes of which depend on the chitosan concentration. Charge neutralization and aggregation of the liposomes occurs at low chitosan concentration. Increasing its concentration produces positive charge on the surface of the liposomes and decreases their size. This increases the stability of the liposomal particles in solution. Liposomes coated with chitosan may be of interest as carriers for genes, vaccines, and drugs.     

Electrospun chitosan-coated fibers of poly(L-lactide) and poly(L-lactide)/poly(ethylene glycol): preparation and characterization

Fibrous poly(L-lactide) (PLLA) and bicomponent PLLA/poly(ethylene glycol) mats were prepared by electrospinning and then were coated with chitosan. The presence of chitosan coating was proved by scanning electron microscopy and by fluorescence microscopy. On contact with blood, the chitosan coating led to changes in erythrocyte shape and in their aggregation. The haemostatic activity of the mats increased with increasing chitosan content. Microbiological studies against Staphylococcus aureus revealed that the chitosan coating imparts antibacterial activity to the hybrid mats. The combined haemostatic and antibacterial activities render these novel materials suitable for wound-healing applications.     

Effect of glycol chitosan on functional and structural properties of anionic liposomes

The possibility of using glycol chitosan to obtain stabilized liposome containers for doxorubicin delivery is demonstrated. The dissociation constants of the liposome complexes with glycol chitosan (3.4 × 10^–4 and 1.10 × 10^–5 depending on the aggregation state of the liposomes) are determined. It is shown that the formation of liposome complexes with glycol chitosan has a significant prolongation effect on the release of doxorubicin from the liposomes at pH 7.4.     

The aggregation behavior of O-carboxymethylchitosan in dilute aqueous solution

O-Carboxymethylchitosan (OCMCS) is a kind of biocompatible derivatives of chitosan whose water solubility is strongly dependent on the degree of carboxymethylation. The OCMCS with 100 carboxymethyl groups and 75 amino groups per 100 anhydroglucosamine units of OCMCS was synthesized by the reaction of chitosan and monochloroacetic. When OCMCS was dissolved in water, its solution was neutral and OCMCS behaved like a weak polyanionic polyeclectrolyte because most of carboxylic groups were not dissociated in neutral aqueous solution. The aggregation behavior of OCMCS in aqueous solution was studied by surface tensiometry, steady-state fluorescence spectroscopy and viscometry. The critical aggregation concentration (cac) of OCMCS was determined to be between 0.042 mg/ml and 0.050 mg/ml. The possible aggregation mechanism of OCMCS in water was elucidated.     

Novel Method to Graft Chitosan on the Surface of Hydroxyapatite Nanoparticles via ＂Click＂ Reaction

In order to tune the surface properties of hydroxyapatite（HA） nanoparticles and prevent them from ag- gregation, an efficient method was proposed to graft chitosan（CS） molecules on the surface of HA via ＂click＂ reac- tion. Thermal gravimetric analysis（TGA） shows that CS was successfully grafted on the surface of HA nanoparticles and the grafting amount was about 8.9 g of CS on per hundred grams of HA. The grafted chitosan chains can prevent HA nanoparticles from aggregation and greatly enhance the colloidal stability of HA in water. The 3-（4,5-dimethylthiazoyl-2-yl）-2,5-diphenyltetrazolium bromide（MTT） assay demonstrats that the cytotoxicity of CS modified HA（HA-CS） is negligible and thus HA-CS may find potential application in biomedical fields.     

Study of Aggregation of Gold Nanoparticles in Chitosan

In this work it is reported the synthesis of gold nanoparticles supported in situ in chitosan by solvated metal atom dispersion technique in order to study the inclusion of Au nanoparticles in the biopolymer matrix. To study their aggregation along time and compare with the synthesis of Au/2-propanol colloid by chemical liquid deposition technique. Studies of Au nanoparticles aggregation along time, supported nanoparticles and colloidal nanoparticles morphology were also carried out. The characterization of Au nanoparticles was performed by transmission electron microscopy, field-emission and scanning electron microscopy, infrared spectroscopy, X-ray diffraction, light scattering and ultraviolet–visible spectroscopy. Metal colloid showed fractal agglomeration type and delay time after the synthesis, the agglomeration size increased to flocculate. Au nanoparticles supported in chitosan showed the same shape as colloids and fractal aggregation was mostly distributed on the matrix.     

Biological activity of chitosan–sugar hybrids: specific interaction with lectin

The specific interactions between lectins and chitosan–sugar hybrids, the synthesized chitosan derivatives linking carbohydrate residue to the amino group of chitosan, were investigated. The specific bindings of chitosan‐L ‐fucose (Fuc) hybrid with Ulex europaeus agglutinin I (UEA I, a lectin specific to L ‐Fuc), and chitosan‐N‐acetyl‐D ‐glucosamine (D ‐GlcNAc) hybrid with Concanavalin A (Con A, a lectin specific to D ‐glucose, D ‐mannose and D ‐GlcNAc), were confirmed by a surface plasmon resonance technique. The microscopic observation of Pseudomonas aeruginosa, which was preincubated with the fluorescein isothiocyanate‐labeled chitosan‐L ‐Fuc hybrid, showed bacteria aggregation. The aggregation was thought to be resulted from the specific interaction of the L ‐Fuc residue of the hybrid with PA‐II lectin on the surface of P. aeruginosa. The chitosan‐L ‐Fuc hybrid inhibited P. aeruginosa growth more effectively in comparison with the other hybrids or unmodified chitosan. The enhancement of antimicrobial activity of chitosan‐L ‐Fuc hybrid could be attributed to the specific binding between PA‐II lectin of P. aeruginosa and L ‐Fuc residue of the L ‐Fuc hybrid. Copyright © 2000 John Wiley & Sons, Ltd.