| Volatile organic compounds (VOCs), which are commonly found in petroleum and chemicals, printing, pharmacy, painting and other industrial processes, are kinds of typical air pollutants. Most of them have characters of multi-kinds, complex component, harmful to human body and difficult to handle. Recently, there are some researches on removing VOCs, and several technologies have been developed. Adsorption has been considered to be superior to other techniques for decontamination in view of its comparatively low costs, wide range of applications, simplicity of design, easy operation, low harmful secondary products and facile regeneration of the adsorbents. However, the core of this process technology is to develop suitable adsorbents. As an emerging VOCs adsorption material, nonwoven has been attracting attention more and more, because of high external surface area, low pressure drops, and flexibilityIn this paper, PP nonwoven fabric was employed as a matrix for the preparation of a novel kind of VOCs adsorbent by graft polymerization and subsequent self-assembly on the surface of PP nonwoven fabric. The adsorbent was prepared by three steps:First of all, the acrylic acid (AA) as a hydrogen donor was introduced onto the surface of PP nonwoven by electron beam induced graft polymerization. Secondly, preparation of poly(DVB-co-4VPy) microspheres by distillation-precipitation polymerization and their reaction with 4-Vinypridine to obtain pyridyl groups. At last, the poly(DVB-co-4VPy) microspheres were introduced onto the surface of PP-g-AA nonwoven through the hydrogen-bonding interaction between the carboxylic acid group and pyridyl group of 4-vinylpyridine (4-VPy). Effects of graft copolymerization conditions to PP-g-AA nonwoven were discussed. Meanwhile, the effects of the self-assembly reaction conditions such as grafting degree of AA, content of pyridine, mass ratio of microsphere to nonwoven, pH and solvent were studied. The results showed that the optimal conditions for the self-assembled reaction were using grafting degree of AA 70%, content of pyridine 25%, mass ratio of microsphere to nonwoven 1/1 (g/g), pH 6 and acetonitrile as the solventTo investigate the structure, composition and wettability of the modified nonwovens, the scanning electron microscopy (SEM), Fourier transform infraredspectrometer (FT-IR), X-ray photoelectron spectroscopy (XPS), N2 absorption-desorption (BET) and contact angle were used to characterize the self-assembly nonwoven. The adsorption properties of the modified PP nonwovens for VOCs were studied by dynamic adsorption experiments, discussing the effects of RWG, temperature, flow rate, concentrations and gas species to breakthrough curves. Besides, pressure drop measurements were conducted to evaluate air permeability. In addition, because of the different force of interaction between the adsorbate and the surface of adsorbent, the self-assembled nonwoven possessed a high adsorption capacity for styrene, which could be explained by the π-π interactions between styrene molecule and benzene rings of self-assembled nonwoven. It was quite clear that 28.2% PM/PP nonwoven obtained the largest adsorption amount (52.8mg/g), which was 88 times greater than that of original PP. Particularly, the permeability (685.05 mm/s) was decreased slightly through adding the microspheres among PM/PP nonwovens. These results demonstrated that the self-assembled nonwoven we prepared still keep good permeability. Taken together, the self-assembled nonwoven possessed a good adsorption performance and air permeability, which could be used as a stand-alone device to removing VOCs.
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