In this paper, the multiwalled carbon nanotubes (MWCNTs) were modified with chitosan (CS) by using low temperature plasma grafting technique (denoted as MWCNT-CS). The prepared MWCNTs and MWCNT-CS were characterized by SEM, TEM, FTIR and Raman spectroscopy in detail and the results suggested that CS molecules were successfully grafted on the surfaces of MWCNTs. The materials were applied as adsorbents in the removal of U(VI) ions from large volumes of aqueous solutions as a function of environmental conditions. The removal of U(VI) from aqueous solution to MWCNTs and MWCNT-CS increased with increasing pH values at pH < 7, and then decreased with increasing pH values at pH > 7. The sorption of U(VI) on MWCNTs and MWCNT-CS was strongly dependent on pH and independent of ionic strength. The sorption of U(VI) on MWCNTs and MWCNT-CS was dominated by inner-sphere surface complexation rather than by ion exchange or outer-sphere surface complexation. The surface grafted chitosan molecules can enhances U(VI) sorption on MWCNTs obviously, which was also evidenced from the XPS spectroscopy analysis. The results of high sorption capacity of U(VI) on MWCNT-CS suggest that the MWCNT-CS nanomaterial is a suitable candidate in the preconcentration of U(VI) ions from large volumes of aqueous solutions. 相似文献
A liquid chromatographic method was developed for the simultaneous quantification of four major active components in tobacco (Nicotiana tobaccum L.) wastes. Samples were extracted with 70% v/v aqueous methanol, four compounds including chlorogenic acid, cryptochlorogenic acid, neochlorogenic acid and caffeic acid were identified and determined by using LC coupled to electrospray tandem mass spectrometry and LC–UV method, respectively. Separation in LC–UV was on an Alltima C18 column (250 mm × 4.6 mm i.d.; 5 μm) with a mobile phase consisting acetonitrile: ammonium acetate buffer (pH 4.5) (5:95 v/v), at a flow rate of 1.0 mL min−1, detected at 327 nm. Four regression equations showed good linear relationships (r2 > 0.999) between the peak area of each marker and concentration. The method has good repeatability and precision, the intra-day and inter-day RSD for both retention time and peak area was less than 1.0%. The recoveries, measured at three concentration levels, varied from 96.33 to 101.10%. The LOD (S/N = 3) and LOQ (S/N = 6) were less than 0.010 and 0.795 μg·mL−1, respectively. This assay was successfully applied to the determination of four active compounds in ten samples. The results indicated that the developed assay method was rapid, accurate, reliable and could be readily utilized as a quantitative analysis method for various of tobacco wastes.
Research on Chemical Intermediates - A practical synthesis of propargylic alcohols was developed by alkynylation of aldehydes mediated by zinc and allyl bromide. Aromatic, aliphatic and vinyl... 相似文献