共查询到20条相似文献,搜索用时 46 毫秒
1.
交联壳聚糖树脂对Ni(II)的吸附行为研究 总被引:7,自引:0,他引:7
研究了甲醛、环氧氯丙烷交联壳聚糖树脂(AECTS)对Ni(II)的吸附行为和吸附Ni(II)对树脂结构及性能的影响. 用FTIR, WAXD, TGA和DSC对吸附产物进行了结构表征, 并深入分析了AECTS与Ni(II)之间的作用机理. 结果表明: AECTS主要以配位形式吸附Ni(II); AECTS吸附Ni(II)后, 结晶度下降、总体上热稳定性变差; Ni(II)对AECTS的主链分解具有明显的催化功能, 而空气气氛中对AECTS在500 ℃附近的分解表现出火焰缓蚀作用. AECTS对Ni(II)的吸附行为符合Langmuir模型, 属于单分子层吸附, 所有吸附位对Ni(II)的作用近似相同; 与壳聚糖(CTS)比较, 造成AECTS对Ni(II)吸附量增大的主要原因是AECTS结晶度下降和孔隙率增加, 二者导致在交联处理前Ni(II)难于接近的吸附位点“活性”相对增大, 使其更容易与Ni(II)相结合; 不同介质对AECTS吸附Ni(II)的影响大小顺序为HCl>CdCl2>MgCl2>NaCl, 前两者使吸附量减小, MgCl2使吸附量稍有增加, NaCl对吸附量基本没有影响. 相似文献
2.
交联壳聚糖树脂吸附Co2+的机理研究 总被引:1,自引:0,他引:1
研究了甲醛、环氧氯丙烷交联壳聚糖 (AECTS) 对Co2 的吸附热力学行为,用FTIR、WXRD对吸附产物进行了结构表征,并研究了溶液中介质种类的不同对Co2 吸附量的影响.结果表明:AECTS主要以配位吸附和物理吸附形式吸附Co2 ;树脂与Co2 配位后,结晶度下降;AECTS对Co2 的吸附行为同时符合Freundlich模型和Langmuir模型;吸附为自发的、放热的熵减小过程;不同介质对树脂吸附Co2 的影响大小顺序为HCl>CdCl2>MgCl2>NaCl,前两者使吸附量减小,后两者使吸附量增加,作用机理相差较大. 相似文献
3.
4.
5.
交联壳聚糖树脂与Zn2+的配位作用 总被引:1,自引:1,他引:1
研究了甲醛、环氧氯丙烷交联壳聚糖树脂(Chitosan crosslinked by aldehyde and epichlorohydrin,AECTS)吸附Zn2 后对树脂结构及性能所产生的影响.用FTIR、XRD、TG、DSC和SEM对吸附产物进行了结构表征,并分析了AECTS与Zn2 之间的作用机理.结果表明,Zn2 与AECTS中的氨基发生配位而被吸附;AECTS吸附Zn2 后,结晶度下降、总体上热稳定性变差;Zn2 对AECTS的主链分解具有明显的催化功能;Zn2 的配位使得AECTS的表面形态发生了改变. 相似文献
6.
交联壳聚糖树脂与Zn2+的配位作用 总被引:2,自引:0,他引:2
研究了甲醛、环氧氯丙烷交联壳聚糖树脂(Chitosan crosslinked by aldehyde and epichlorohydrin,AECTS)吸附Zn2 后对树脂结构及性能所产生的影响.用FTIR、XRD、TG、DsC和SEM对吸附产物进行了结构表征,并深入分析了AECTS与Zn2 之间的作用机理.结果表明,Zn2 与AECTS中的氨基发生配位而被吸附;AECTS吸附Zn2 后,结晶度下降、总体上热稳定性变差:Zn2 对AECTS的主链分解具有明显的催化功能;Zn2 的配位使得AECTS的表面形态发生了改变. 相似文献
7.
交联壳聚糖对Zn2+的吸附性能 总被引:1,自引:0,他引:1
研究了甲醛、环氧氯丙烷交联壳聚糖树脂(AECTS)对Zn 2 的吸附行为,探讨温度、溶液的pH、反应时间、再生次数等因素对吸附性能的影响,并用红外光谱(FTIR)和光电子能谱(XPS)对吸附产物表面的元素结构及其结合能的变化进行表征. 结果表明,AECTS对Zn 2 的吸附导致AECTS结构和性能发生显著变化. FTIR和XPS分析表明,Zn 2 以配位键的形式吸附于AECTS,使AECTS中氨基的伸缩振动、变形振动发生了明显变化,N原子发生化学位移,而AECTS分子链上的羟基没有直接参与配位反应;AECTS对Zn 2 有较强的吸附能力和较快的吸附速率,在30 ℃、Zn 2 初始质量浓度为1 g/L的溶液中,吸附量可达163 mg/g树脂,是壳聚糖饱和吸附量的1.7倍左右;吸附量受pH的影响较大,在pH=5时吸附量最高;AECTS对Zn 2 的吸附行为符合Freundlich等温吸附方程,温度升高吸附量增大,该过程为一吸热过程;AECTS经再生重复使用5次,吸附量基本不变. 相似文献
8.
9.
10.
利用滴加法合成了球形含Ni2 交联壳聚糖,并通过胺化引入大量活性氨基,再经除镍制成对重金属镍离子具有较好吸附能力的新型吸附剂[P-C-CTS(Ni)].通过Ni2 吸附容量的测定,IR及XPS分析,验证了合成技术路线的正确性.通过研究pH值对吸附量的影响,初步讨论了无柠檬酸根(Cit)配位体存在时,吸附剂对Ni(II)的吸附为螯合作用.通过Cit存在条件下(cNi=cCit=0.852mmol·L-1),吸附剂对Ni(II)离子和Cit的吸附量随pH值的变化,结合相应pH值下金属镍的形态分布,探讨了其对Ni(II)的吸附机理,研究认为不仅仅是简单的螯合作用,其吸附机理和吸附量与溶液中金属离子的存在形式有关,引入静电吸附原理解释了吸附剂对Ni(II)的吸附现象. 相似文献
11.
An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions. 相似文献
12.
Uroš Grošelj Mojca Žorž Amalija Golobič Branko Stanovnik Jurij Svete 《Tetrahedron》2013,69(52):11092-11108
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives. 相似文献
13.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion. 相似文献
14.
N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%). 相似文献
15.
An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction. 相似文献
16.
The Diels-Alder reactivity of 1,2-heteroborines (H4C4B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed. 相似文献
17.
Xi-Liu YunWen-Ying Bi Jian-Hui HuangYu Liu Daisy Zhang-NegrerieYun-Fei Du Kang Zhao 《Tetrahedron letters》2012,53(38):5076-5080
A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd2(dba)3-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring. 相似文献
18.
Shashikant U. Dighe Surya K. Samanta Shivalinga Kolle Sanjay Batra 《Tetrahedron》2017,73(17):2455-2467
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones. 相似文献
19.
In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates. 相似文献
20.
Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles. 相似文献