Solid-phase extraction of explosive nitramines on macroreticular polymers modified by freezing with water or acetone

Abstract

A novel approach is proposed to modify the porous structure and surface properties of the polymers used in solid-phase extraction. The approach involves soaking in water or acetone, followed by freezing in liquid nitrogen (77.4 K) and was employed for two polymeric materials: Amberlite XAD-7 and Amberlite XAD-16. Variations in the surface properties of the adsorbents were justified by the action of acetone and water as solvents affecting the textural and other characteristic of the materials. The initial and treated adsorbents were used in extraction of explosive nitramines from aqueous samples. The performed modifications of the polymer texture allow us to increase the recovery rate as compared with the initial adsorbents. The results were justified by the swelling of fragments of the polymers and by the additional process of sorption of nitramines. The results indicate that polymeric adsorbents can be easily modified by the soaking/freezing process and the materials can be achieved that prove usefulness for the effective separation of explosive nitramines from aqueous samples.

Polymer Adsorbents vs. Functionalized Oxides and Carbons: Particulate Morphology and Textural and SurfaceCharacteristics

“…Therefore, a set of methods could be used in parallel, such as direct (TEM, SEM) and indirect (probe adsorption, SAXS, NMR cryoporometry, DSC thermoporometry, etc.) methods [9,28,31,[54][55][56][64][65][66][74][75][76][77][78][79][80][81][82][83][84][85][86][87]111,[114][115][116][117][118][119][120][121][122][123][124][125][126][127][128][129][130]. More accurate results can be obtained if several methods are used in parallel (e.g., SAXS and adsorption).…”

“…Additionally, complex and hybrid systems with PVA/AC, fumed silica/PDMS, etc., are described here mainly concerning the morphological and textural characteristics. All these materials can be considered as representatives of various classes of simple and complex adsorbents and polymer fillers described in detail elsewhere [4][5][6][7][8][9][10][11][12]28,31,32,[54][55][56][74][75][76][77][78][79][80][81][82][83][84][85][86][87][89][90][91]. Some details on the materials used here are given in the Supplementary Materials file.…”

“…Therefore, additional methods, such as small-angle X-ray or neutrons scattering (SAXS, SANS) [53][54][55][56][57][58], X-ray diffraction (XRD) [59][60][61], high-resolution transmission (HRTEM) and scanning (SEM) electron microscopies [59,62], nuclear magnetic resonance (NMR) spectroscopy with cryoporometry and relaxometry [15,[63][64][65], differential scanning calorimetry (DSC) and thermoporometry [66], infrared spectroscopy (FTIR), thermogravimetry (TG) and thermoporometry, dielectric relaxation spectroscopy (DRS), thermally stimulated depolarization current (TSDC) and relaxometry, theoretical simulations, etc. [67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84][85][86] should be used. Besides the textural characteristics, the data of these methods allow one to obtain information on the materials' behavior under different conditions, which could model real situations related to practical applications.…”

“…To analyze these dependencies (typically complex for complex materials), certain model equations should be used and treated with the applied mathematics methods (used, e.g., to solve integral and differential equations, to minimize functionals, to regularize experimental noise effects, etc.) and related computer programs [3][4][5][6][7][8]31,32,[53][54][55][56]63,64,[74][75][76][77][78][79][80][81][82][83][84][85][86][87]. Even if the experimental methods give direct information (e.g., TEM, SEM) that certain computer methods and programs should be used to obtain quantitative characteristics, e.g., the particulate morphology, porosity, particle and crystallite size distributions, etc.…”