Synthesis of polyamine‐bridged polysilsesquioxanes and their adsorption properties for heavy metal ions

Abstract

Four types of polyamine‐bridged polysilsesquioxane adsorbents were prepared via a facile sol‐gel method using pre‐synthesized ethanediamine (EDA)‐ and diethylenetriamine (DETA)‐bridged monomers containing soft organic bridge. Infrared spectra (IR), scanning electron microscope (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TG), elemental analysis, and nitrogen gas adsorption–desorption were used to characterize their structures. Porogen hexadecyl tyimethyl ammonium bromide (CTAB) was found to be efficient in increasing the porosity of the absorbents. Adsorption experiments at different temperatures showed that the obtained absorbents exhibited relatively high adsorption capacities for Hg(II). Pseudo second‐order model is more suitable for describing the adsorption kinetics in the temperature range of 15–35°C. Compared with Freundlich models, Langmuir isotherm was better to describe the adsorption process of Hg(II) for all adsorbents. Finally, the thermodynamic parameters demonstrated that the adsorption reaction was endothermic and spontaneous. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1089–1099, 2017

Allyl and Benzyl Modified Aramid Nanofibers as an Enhancement in Polystyrene-Based Composites

“…Figures 5 , 6 show the XPS wide scan spectra of different samples and the C1s spectra of three samples after the split-peak. It can be seen from the C1s spectrogram that after modification by allyl or benzyl, not only the chemical groups of aramid fiber are retained, but also the -C=C bond of allyl and the -C-H bond of benzyl benzene ring are introduced into the aramid fiber (Sun et al, 2012 , 2014 ; Zhang et al, 2017 ). The different peak intensities of C1s and O1s in the full spectra may also indicate the introduction of allyl or benzyl groups on the aramid nanofibers (Guo et al, 2009 ; Jia et al, 2010 ; Cheng et al, 2016 ).…”

Blue Fluorescent Nitrogen‐Doped Carbon Dots for the Specific Detection of Mn2+

“…The presence of the amino group was confirmed by the C−N stretching vibration at 1120 cm −1 . The absorption peaks at 2920 cm −1 and 2850 cm −1 belong to the asymmetric and symmetric ‐CH 2 ‐ stretching vibration [37] . The N−H vibration was sited at 1600 cm −1 in DETA [38] .…”

“…The absorption peaks at 2920 cm À 1 and 2850 cm À 1 belong to the asymmetric and symmetric -CH 2 -stretching vibration. [37] The NÀ H vibration was sited at 1600 cm À 1 in DETA. [38] However, after the reaction, the absorption peak of NÀ H shifted to the direction of low wavenumber and was located at 1575 cm À 1 .…”

Synthesis of polyethyleneimine modified polyurethane foam for removal of Pb(II) ion from aqueous solution

“…Various techniques have been studied for removal of Pb(II) from water, such as chemical precipitation, membrane filtration, ion exchange, solvent extraction and adsorption [8,9]. Adsorption is recognized as an easy and effective method owing to its low cost, simplicity for design, easy operation and reversibility [10][11][12]. Nowadays, a variety of adsorbents have been developed for Pb(II) removal, such as activated carbon [13], clay minerals [14], carbon nanotubes [15], zeolite [16], polymer resin [17], silica gel [18]and polyurethane foam (PUF).…”