A fixed-bed method is proposed to test materials for HCl removal from hydrogen gas.• Zeolite X was the best performing material among screened zeolites.• Ion-exchanged X zeolites were successfully produced, characterized and evaluated.• HCl removal from hydrogen gas occurred through reaction with the zeolite cations.• Cation type and hydration significantly influenced the HCl removal performance.
For
the first time, low trace-level removal of perfluorooctanesulfonic
acid (PFOS), i.e., 20–500 μg/L (ppb), from aqueous solutions
using zeolitic imidazolate framework-8 (ZIF-8)-coated copper sheet
(ZIF-8@Cu) composite is reported here. In comparison with different
commercial activated carbon (AC) and all-silica zeolites, the composite
showed the highest removal rate of 98%, which remained consistent
over a wide range of concentrations. Additionally, no adsorbent leaching
from the composite was noticed, which eradicated pre-analysis steps
such as filtration and centrifugation, unless needed for other adsorbents
studied here. The composite displayed fast uptake with saturation
reaching within 4 h, irrespective of the initial concentration. However,
the morphological and structural characterization revealed surface
degradation of ZIF-8 crystals, along with a decline in the crystal
size. The adsorption of PFOS on ZIF-8 crystals was linked to chemisorption,
as the surface degradation surges with an increase in PFOS concentration
or with cyclic exposure at low concentrations. Methanol seemingly
removed surface debris (partially), thus providing access to ZIF-8
beneath the surface debris. Overall, the findings demonstrate that
at low trace ppb-level PFOS concentrations ZIF-8 can be considered
as a possible candidate for PFOS removal, even though it suffers slow
surface degradation, it also removes efficiently PFOS molecules from
aqueous solutions.
We report on the first successful attempt to produce a silica/polymer composite with retained C18 silica sorptive properties that can be reliably printed using three-dimensional (3D) FDM printing. A 3D printer provides an exceptional tool for producing complex objects in an easy and inexpensive manner and satisfying the current custom demand of research. Fused deposition modeling (FDM) is the most popular 3D-printing technique based on the extrusion of a thermoplastic material. The lack of appropriate materials limits the development of advanced applications involving directly 3D-printed devices with intrinsic chemical activity. Progress in sample preparation, especially for complex sample matrices and when mass spectrometry is favorable, remains a vital research field. Silica particles, for example, which are commonly used for extraction, cannot be directly extruded and are not readily workable in a powder form. The availability of composite materials containing a thermoplastic polymer matrix and dispersed silica particles would accelerate research in this area. This paper describes how to prepare a polypropylene (PP)/acrylonitrile−butadiene−styrene (ABS)/C18-functionalized silica composite that can be processed by FDM 3D printing. We present a method for producing the filament as well as a procedure to remove ABS by acetone rinsing (to activate the material). The result is an activated 3D-printed object with a porous structure that allows access to silica particles while maintaining macroscopic size and shape. The 3D-printed device is intended for use in a solidphase microextraction (SPME) procedure. The proposed composite's effectiveness is demonstrated for the microextraction of glimepiride, imipramine, and carbamazepine. The complex honeycomb geometry of the sorbent has shown to be superior to the simple tubular sorbent, which proves the benefits of 3D printing. The 3D-printed sorbent's shape and microextraction parameters were fine-tuned to provide satisfactory recoveries (33−47%) and high precision (2−6%), especially for carbamazepine microextraction.
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