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1.
SYNTHESIS AND PROPERTIES OF SULFHYDRYL CHITOSAN 总被引：1，自引：0，他引：1
A new adsorbent for heavy metal ions, sulfhydryl chitosan (S-chitosan), was produced by treatment of chitosan with sulhydryl acetic acid in the presence of sulfuric acid as a catalyst. Its structure was confrrmed by elemental analysis and FI‘-IR spectra analysis. The adsorption properties of sulthydryl chitosan for Cu(Ⅱ ), Cd(Ⅱ ), Pb(Ⅱ), Cr(Ⅲ) and Ni(Ⅱ) were investigated, and the effect of pH value on adsorption, adsorption kinetics, and selective adsorption was examined. It was shown that S-chitosan has good adsorption for Pb(Ⅱ), Cu(Ⅱ) and Cd(Ⅱ) like chitosan, is also insoluble in acid solution; has good adsorption kinetic properties for heavy metal ions; and can be used in acid solution. The adsorption capacities of S-chitosan can be affected by media acidity. The adsorbed Cu(Ⅱ) Cd(Ⅱ) and Pb(Ⅱ) could be eluted by diluted chlorhydric acid. 相似文献
2.
Chitosan composites and derivatives have gained wide attentions as effective biosorbents due to their low costs and high contents of amino and hydroxyl functional groups. They have showed significant potentials of removing metal ions, dyes and proteins from various media. Chemical modifications that lead to the formation of the chitosan derivatives and chitosan composites have been extensively studied and widely reported in literatures. The aims of this review were to summarize the important information of the bioactivities of chitosan, highlight the various preparation methods of chitosan-based active biosorbents, and outline its potential applications in the adsorption of heavy metal ions, dyes and proteins from wastewater and aqueous solutions. 相似文献
3.
In order to synthesize an improved adsorbent for heavy metal ions, we studied the condensation reaction of chitosan with salicylaldehyde
in ethanol to form a Schiff base. The effect irradiating the reaction using an ultrasonic liquid processor was contrasted
with conventional methods. The IR spectra of condensed chitosan prepared by the two methods showed that their molecular structures
were identical. The reaction conditions, including solvents, ultrasonic power density and irradiation time, pH, and reactant
ratio, were optimized by orthogonal design. A shorter reaction time and a higher product yield were obtained using ultrasonic-assisted
synthesis compared with the traditional method. A condensation degree of 89.63% was achieved using the optimized conditions:
i.e. ultrasonic irradiation at 180 W for 60 min; 95% ethanol as the solvent, pH 4.0, and salicylaldehyde:chitosan ratio of
6:1. 相似文献
4.
本文根据飞机探测的云物理资料,分析西南低涡云系的云滴特征,并与切变云系的微结构特征作了对比分析。指出:西南涡云系和切变云系的平均谱都是单峰谱,两者的差异不大。两类系统自身的强、弱云系之间,在谱宽、平均滴直径、滴浓度及其分布等方面都存在明显的差别。 相似文献
5.
Analgesis and wound healing effect of chitosan and carboxymethyl chitosan on scalded rats were investigated. A II degree scald model was established in rats, which was subsequently treated with chitosan and carboxymethyl chitosan solution, respectively. The concentration of bradykinin and 5-hydroxytryptophan was detected by assaying enzyme-linked immunosorbent. Healing condition was observed and pathological sections were made to determine the healing effect of chitosan and carboxymethyl chitosan. Results showed that the concentration of bradykinin and 5-hydroxytryptophan peaked at the third hour post-wound in all groups, while the concentration of hydroxyproline peaked at the seventh day post-wound in both chitosan and carboxymethyl chitosan group. The concentration of bradykinin and 5-hydroxytryptophan of carboxymethyl chitosan group was significantly lower than that of control (P < 0.05), while that of chitosan group was similar to that of control (P > 0.05). These findings indicated that carboxymethyl chitosan reduced the concentration of algogenic substances, resulting in analgesia. During the whole recovery process, the hydroxyproline concentration in chitosan and carboxymethyl chitosan group on day 3 and 7 was significantly higher than that of control (P < 0.01); however the significance of such a highness decreased on day 14 (P < 0.05). These findings indicated that chitosan and carboxymethyl chitosan accelerated tissue repair. Meanwhile, chitosan performed better in healing than carboxymethyl chitosan in both decrustation and healing time. In conclusion, carboxymethyl chitosan showed significant analgesis and wound-healing promotion effect, but chitosan only showed wound-healing promotion effect. 相似文献
6.
从甲壳素出发,先制备了3种不同脱乙酰度的壳聚糖,选择过硫酸铵_亚硫酸氢钠为氧化还原体系引发剂,合成了壳聚糖接枝丙烯酰胺聚合物;通过红外光谱,电镜扫描对聚合物进行结构表征,结果表明壳聚糖结构发生了变化,通过在相同条件下比较壳聚糖不同脱乙酰度对接枝率的影响,得出了在脱乙酰度为68.5%时聚合物的接枝率最大为250%,其最佳合成工艺为∶m(壳聚糖)∶m(丙烯酰胺)=1∶5,引发剂用量为体系质量分数的0.3%~0.4%,温度55~60℃,反应时间为2.5~3.0 h。 相似文献
7.
Chitosan composites and derivatives have gained wide attentions as effective biosorbents due to their low costs and high contents of amino and hydroxyl functional groups. They have showed significant potentials of removing metal ions, dyes and pro- teins from various media. Chemical modifications that lead to the formation of the chitosan derivatives and chitosan composites have been extensively studied and widely reported in literatures. The aims of this review were to summarize the important information of the bioactivities of chitosan, highlight the various preparation methods of chitosan-based active biosorbents, and outline its potential applications in the adsorption of heavy metal ions, dyes and proteins from wastewater and aqueous solutions. 相似文献
8.
新型壳聚糖季铵盐衍生物的合成与表征 总被引：2，自引：0，他引：2
采用甲磺酸作为溶剂兼作氨基保护试剂,对壳聚糖上的羟基选择性酯化,再游离出氨基并对其氯乙酰化,最后进行吡啶成盐,得到新型水溶性的壳聚糖季铵盐衍生物,产物的结构通过核磁共振氢谱和红外光谱进行了表征,从而为壳聚糖季铵盐衍生物的制备提供了一种新途径。 相似文献
9.
制备条件对聚乙烯醇-壳聚糖凝胶性能的影响 总被引：1，自引：0，他引：1
以戊二醛为交联剂,由聚乙烯醇(PVA)和壳聚糖(CTS)混合交联得到一种水凝胶,考察了聚乙烯醇和壳聚糖的配比、交联剂用量和反应时间对聚乙烯醇/壳聚糖凝胶吸水率的影响。通过单因素实验,得出了聚乙烯醇/壳聚糖凝胶具有最佳溶胀性能时的条件:聚乙烯醇与壳聚糖的摩尔比为6∶1,交联剂戊二醛的体积分数为0.05%,反应时间9h。测定了该凝胶在不同pH值下的吸水率和吸附铜离子的性能,得出聚乙烯醇/壳聚糖凝胶在酸性介质的吸水率远远大于碱性介质,对铜离子(Cu2+)的吸附量比壳聚糖凝胶提高了33.7%,因此该凝胶吸附剂在工业废水处理重金属离子方面具有一定的优越性。 相似文献
10.
Chitosan is a natural polysaccharide prepared by the N-deacetylation of chitin. In this paper we have reviewed the methods of preparation of chitosan-based nanoparticles and their pharmaceutical applications. There are five methods of their preparations： emulsion cross-linking, emulsion-droplet coalescence, ionic gelation, reverse micellar method and chemically modified chitosan method. Chitosan nanoparticles are used as carriers for low molecular weight drug, vaccines and DNA. Releasing characteristics, biodistribution and applications are also summarized. 相似文献
11.
ZHOU Li XU Junming SONG Yimin GAO Yuanyuan CHEN Xiguang 《中国海洋大学学报(英文版)》2007,6(3):249-254
The captopril/Chitosan-gelatin net-polymer microspheres(CTP/CGNPMs) were prepared using Chitosan(CTS) and gelatin(GT) by the methods of emulsification,cross-linked reagent alone or in combination and microcrystalline cellulose(MCC) added in the process of preparation of microspheres,which aimed to eliminate dose dumping and burst phenomenon of microspheres for the improvement of the therapeutic efficiency and the decrease of the side effects of captopril(CTP). The results indicated that CTP/CGNPMs had a spherical shape,smooth surface and integral structure inside but no adhesive phenomena in the preparation. The size distribution ranged from 220 μm to 280 μm. The CTP release test in vitro demonstrated that CTP/CGNPMs played the role of retarding the release of CTP compared with ordinary CTP tablets. The release behaviors of CGNPMS were influenced by preparation conditions such as experimental material ratio(EMR) and composition of cross linking reagents. Among these factors,the EMR(1/4),CLR(FA SPP) and 0.75% microcrystalline cellulose(MCC) added to the microspheres constituted the optimal scheme for the preparation of CTP/CGNPMs. The ER,DL and SR of CTP/CGNPMs prepared according to the optimal scheme were 46.23±4.51%,9.95±0.77% and 261±42%,respectively. The CTP/CGNPMs had the good characteristics of sustained release of drug and the process of emulsification and cross-linking were simple and stable. The CGNPMs are likely to be an ideal sustained release formulation for water-soluble drugs. 相似文献
12.
ImooUcrIONAtfrequendesseveraltirathatofthespeCtralpcak,thewaveelevationhigherordercomPonentS'contributionstothewavespatrumaremoresignificantthanthosefromthelinearcomPonentS.Tick(l959)firstproposedandevaluatedtheserendxidespodrumofunidindionalrandomwaves.TheexpnaionderivedbyDingPingxingetal.(l994)forthesecondxirderspeCtmmisanimProvernentofTick's.TickandDingPingxingetal.didnotaanuntforthirdxirderperturbations,althoughthethirdxirdersolutionefhaonthequadraticspeCtrumisofthesameorderofmagnit… 相似文献
13.
In this study,the water-based ferromagnetic fluid and magnetic resin made from chitosan and cerium complex(MRCCC) were successfully prepared by using the chemical co-precipitation technique and by the reversed-phase suspension cross-linking polymerization.MRCCC presented uniform and narrow particle size distribution as determined by the Laser Particles Sizer.The Inductively Coupled Plasma-Atomic Emission Spectrometry(ICP-AES),Fourier transform infrared spectroscopy(FT-IR),differential scanning calorimetry(DSC)and X-ray powder diffraction(XRD)study demonstrated that there were iron and cerium existing in MRCCC.The movement of MRCCC under magnetic field proved its magnetic property.The swelling kinetics in water or solutions with different pH indicated that MRCCC could be applied in solutions with pH greater than 1.0.The ferromagnetic fluid particles were stable in MRCCC soaked in solutions with pH >2.0.In view of these results,MRCCC can be used as material for separation,clarification,adsorption,sustained release and hydrolysis activity. 相似文献
14.
光谱数据变换对消除背景、噪音影响以及提取光谱特征有重要的作用,是光谱数据分析过程中的必要步骤。为了研究光谱变换处理对土壤氮素PLSR模型的影响精度,并选择最佳光谱变换处理方法,本文对原始光谱数据进行了15种典型光谱变换,通过比较不同变换光谱与土壤氮素的相关性,实现土壤氮素的PLSR精确诊断,并综合评定最佳光谱数据变换方法。结果表明,涉及微分处理后的光谱变换,尤其是先进行开方（T8、T11）、对数（T6、T12）等变换后再进行微分处理,可提高其与土壤氮素的相关性。在引入较少因子变量个数的条件下,该方法使因变量解释量达到了98%。综合考虑模型的校正、验证效果及模型复杂度（模型最佳因子变量个数）,可得出光谱平方根的一阶微分变换处理（T8）为最佳的土壤光谱变换算法。该条件下的土壤氮素的校正模型表现为R2=0.985、RMSEC=0.000132、Fn=6,验证模型的表现为R2=0.9853、RMSEV=0.000162,结果表明基于T8的光谱数据变换可实现本试验条件下土壤氮素的光谱估算。另外,可以考虑将原始光谱的一阶微分（T9）、对数和对数倒数的一阶微分（T6、T7）以及平方根和对数的二阶微分（T11、T12）作为光谱数据变换方法。本文研究结果可为土壤氮素估算和光谱数据预处理提供技术参考。 相似文献
15.
Chitosan extends the shelf-life of filleted tilapia (Oreochromis niloticus) during refrigerated storage 总被引：1，自引：0，他引：1
Shelf-life extension of aquatic products is of significant economical importance. To determine the potential effect of chitosan on the shelf-life of filleted tilapia, this study analyzed the bacterial community diversity in fresh and spoiled tilapia fillets stored at (4 ± 1)℃ and examined the antimicrobial activity of chitosan against relevant bacteria isolates. Results showed that Pseudomonas (20%) and Aeromonas (16%) were abundant in fresh tilapia fillets, whereas Pseudomonas (52%), Aeromonas (32%) and Staphylococcus (12%) were dominant in the spoiled samples. Chitosan showed wide-spectrum antibacterial activity against bacteria isolated from tilapia and 5.0 g L-1 chitosan was selected for application in preservation. We further determined the shelf-life of chitosan-treated, filleted tilapia stored at (4 ± 1)℃ based on microbiological, biochemical and sensory analyses. Results showed that the shelf-life of chitosan-treated, filleted tilapia was extended to 12 d, whereas that of untreated, control samples was 6 d. These indicate that chitosan, as a natural preservative, has great application potential in the shelf-life extension of tilapia fillets. 相似文献
16.
珠江口水体叶绿素a浓度高光谱反演研究 总被引：2，自引：0，他引：2
对珠江口水体进行了现场光谱测量和同步的水质采样分析,发现695nm处的一阶导数光谱数据对叶绿素a浓度有很好的指示作用,由此建立了基于695nm处一阶导数光谱数据的叶绿素a浓度的线性模式、二次多项式模式、三次多项式模式和指数模式。两次实验的结果表明:指数模式的R2(确定系数)为0.7584,预测平均相对误差为26.7239,是估算珠江口水体叶绿素a的最佳的模式。 相似文献
17.
Sulfate chitosan derivatives have good solubility and therapeutic effect on the cell model of NAFLD. The aim of this study was to examine the therapeutic effect of sulfate chitosan derivatives on NAFLD. The male Wistar rats were orally fed high fat emulsion and received sulfate chitosan derivatives for 5 weeks to determine the pre-treatment effect of sulfate chitosan derivatives on NAFLD. To evaluate the therapeutic effect of sulfate chitosan derivatives on NAFLD, the rats were orally fed with high concentration emulsion for 5 weeks, followed by sulfate chitosan derivatives for 3 weeks. Histological analysis and biomedical assays showed that sulfate chitosan derivatives can dramatically prevent the development of hepatic steatosis in hepatocyte cells. In animal studies, pre-treatment and treatment with sulfate chitosan derivatives significantly protected against hepatic steatohepatitis induced by high fat diet according to histological analysis. Furthermore, increased TC, ALT, MDA, and LEP in NAFLD were significantly ameliorated by pre-treatment and treatment with sulfate chitosan derivatives. Furthermore, increased TG, AST, and TNF-α in NAFLD were significantly ameliorated by treatment with sulfate chitosan derivatives. Sulfate chitosan derivatives have good pre-treatment and therapeutic effect on NAFLD. 相似文献
18.
宁夏及邻区地震震源参数研究 总被引：1，自引：0，他引：1
利用宁夏地震台网记录的宁夏及邻区数字地震波资料,采用Brune(1970)模型,通过几何扩散校正、介质衰减校正、仪器校正等将速度记录谱归算为震源位移谱。使用遗传算法计算拐角频率及零频极限,进而计算震源半径、地震矩等小震震源参数,并系统分析了各种参数之间的关系。使用发生于2003年6月—2007年12月ML1.7~4.4的186次地震事件估算的震源参数表明:地震矩、近震震级、破裂半径、拐角频率等之间可以拟合为对数或半对数线性关系。地震应力降、视应力与震源半径没有表现出明显的依赖关系,但与地震矩之间表现出正相关关系。与其他地区相比,此研究区属于低应力释放区域。 相似文献
19.
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20.
lareODUcrI0NThephenomenonofbreakingwavesintheoasnoocurswheneveramomentahiyhighcrestmecheSanunstablecondition.It0ccursintendtimhy,andtheoccurrencefre-qUencydePendsonthescastate.ManystudAshaddricaniedoutontheoccurmcefre-qUencyofbrmkingwavesindeepweter.0chiandTsai(l983),LongueHiggins(l975)andVanD0mandPamn(l975)nadstheptalictonofbrmkingwavesoccurrenceindeePwater,usingabaskingcriterionforindividualwavesbasedonthewavesmpness.ThecriterioncanbeexpmeedintennSofthewaVehdghtHandperiodTasH>PgT'(… 相似文献