03568nas a2200217   4500008004100000022001400041245008800055210006900143260009900212300001000311490000700321520275900328653001303087653002503100653002403125653002303149653001503172100002103187700002303208856011903231       2008                        eng d  a0144-861700aComplexation of heavy metals by crosslinked chitin and its deacetylated derivatives0 aComplexation of heavy metals by crosslinked chitin and its deace  aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, OXON, ENGLANDbELSEVIER SCI LTDcJAN  a66-730 v713 a<p>Chitin was crosslinked using diisocyanatohexane (HDI), trimellitic anhydride (TMA), and dibromodecane (DBD), then deacetylated in strong aqueous alkali. This led to a product with amine functional groups on the exposed surface of the crosslinked chitin, which could be utilized for complexation with heavy metals. Thus, a key feature of the crosslinked derivatives prepared was that only the hydroxy Groups were utilized in the crosslinking reaction, and the acetylamino groups of chitin were hydrolyzed only after the crosslinking was accomplished. This ensured that all amino groups of the chitosans so produced would be available for metal complexation, and not partially used up in crosslinking. This proposed advantage was proved by the similar binding observed for heavy metals like Hg (348-372 mg/g), Cu (91-119 mg/g), Zn (71-92 mg/g), Mn (3-10 mg/g), Cd (121-160 mg/g), and Pb (32-86 mg/g) using these crosslinked polymers, whereas the control polymer (uncrosslinked chitosan powder) had complexation values for Hg (348-361 mg/g), Cu (100-106 mg/g), Zn (81-92 mg/g), Mn (4-7 mg/g), Cd (135 mg/g), and Pb (25-59 mg/g). Additionally, in a case where chitosan was crosslinked with HDI. the amino groups were consumed in the crosslinking reaction, and the metal complexation capacity has found to be decreased for Cu (91-109 mg/g), Cd (133 mg/g), and Zn (71-77 mg/g), while remaining nearly the same for Hg (362 mg/g). The literature value for Cu complexation is 59.67 mg/g for chitosan crosslinked with glutaraldehyde. The crosslinked derivatives have the added advantage of insolubility even in low pH aqueous media, making their repeated re-use possible. Further, these crosslinked derivatives could be used in powder form, and the additional step of preparing beads was found to be not necessary for ease of separation of the crosslinked powder by filtration. The binding capacity of various crosslinked chitin and deacetylated derivatives for Cu, Cd, Hg, Zn, Mn. and Pb was in the region of 100, 140, 360 88, 5, and 60 mg/g (rounded off values) of polymer, respectively, very close to the values obtained for uncrosslinked chitosan. The metal binding for crosslinked chitosan was slightly lower than that of crosslinked chitin and deacetylated derivatives, due to use of some amino groups in crosslinking. For Cu ions, the Langmuir equation was found to be the best fit for HDI crosslinked deacetylated chitin and TMA crosslinked deacetylated chitin. The morphological studies conducted using WAXRD are in close agreement with the metal complexation data, showing complete loss of original chitosan peaks for the heavily complexed derivatives, and minor changes for the weakly complexed metals. (c) 2007 Elsevier Ltd. All rights reserved.</p>10aChitosan10aCrosslinked chitosan10adeacetylated chitin10ametal complexation10aMorphology1 aTrimukhe, K., D.1 aVarma, Anjanikumar  uhttps://library.ncl.res.in/content/complexation-heavy-metals-crosslinked-chitin-and-its-deacetylated-derivatives-002068nas a2200241   4500008004100000245012300041210006900164260000800233300000800241490000800249520125500257653002901512653000801541653002301549653001801572100001701590700001401607700001901621700001901640700001701659700002101676856012901697       2017                        eng d00aNovel interaction study of Th(IV) and Zr(IV) with 4-sulfonatocalix[6]arene: experimental and theoretical investigation0 aNovel interaction study of ThIV and ZrIV with 4sulfonatocalix6ar  cNOV  a1370 v1373 a<p>Calixarenes based ligands are well known in the extraction of heavy metal ions. The modifications at lower as well as upper rim increase the new possibilities of metal extraction in terms of quantum and selectivity of metal. In comparison to calix[4]arene, complexing nature of calix[6]arene is less studied due to its large size and flexible nature. In the present study, 4-sulfonatocalix[6]arene (SCX6) is synthesized and an attempt has been made to understand its complexation behavior with Th(IV) and Zr(IV) metal ions. The effect of different solvents has been examined along with calculation of binding constants for better complexation possibilities. Though in general, its complexation proves to be at 1:1 stoichiometry with respect to ligand and metal, the specific metals show its characteristic modes of interaction with the ligand. This has been understood through IR spectroscopic analysis and density functional theory based first principle studies. 1H NMR spectra of SCX6 and its complexes with Th(IV) and Zr(IV) metal ions was established. IR, UV–Vis, fluorescence spectroscopic studies provided a systematic understanding about the binding behavior of these two metals including interference possibilities from other metals.</p>10a4-Sulfonatocalix[6]arene10aDFT10ametal complexation10aTh(IV) Zr(IV)1 aRathod, N.V.1 aJoshi, K.1 aKalyani, V., S1 aJadhav, A., S.1 aSelvaraj, K.1 aMalkhede, D., D.  uhttps://library.ncl.res.in/content/novel-interaction-study-thiv-and-zriv-4-sulfonatocalix6arene-experimental-and-theoretical