Surface-Modified Wrinkled Mesoporous Nanosilica as an Effective Adsorbent for Benzene, Toluene, Ethylbenzene, and Xylene in Indoor Air

Abstract

Surfactant-extracted spherical porous silica nanoparticles with wrinkled structures were synthesized, and their adsorption performance was altered by grafting three organosilanes: n-octyltriethoxysilane, hexadecyltrimethoxysilane, and triethoxyphenylsilane onto their surface. The surface-modified silica nanoparticles were used to capture frequently detected hazardous indoor air chemicals. The physical and chemical properties of the samples were characterized using thermogravimetric analysis, Fourier transform infrared spectroscopy, N 2 adsorption−desorption experiments, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy. Although the organosilane surface modification did not significantly change the surface areas and pore structures of porous silica nanoparticles, the capacities of the surface-modified porous silica nanoparticles for capturing benzene, toluene, ethylbenzene, and xylene (BTEX) molecules from air were considerably higher than those of pristine porous silica nanoparticles. The dispersion forces between adsorbates and adsorbents were the primary factor that affected the absorption capacity of the surface-modified porous silica nanoparticles. Consequently, the BTEX capturing potential of surface-modified mesoporous silica featuring a long alkyl chain was high because of the relatively high dispersion force between adsorbates and the adsorbent.

Deactivation-Tolerance of Heterojunction Anatase and Bronze TiO2 in the Photocatalytic Mineralization of Toluene

“…1,2 VOCs are responsible for sick building syndrome and multiple chemical sensitivities, causing several health issues (e.g., headaches, allergies, and nausea). 3 Among the existing indoor air purification technologies, photocatalysis is considered the most appropriate because of its operation under room temperature and atmospheric pressure without any auxiliary chemicals (e.g., O 3 and H 2 O 2 ) or expensive elements, and because it mineralizes pollutants into H 2 O and CO 2 by in situ generated hydroxyl radicals ( • OH). 4−7 Despite toluene having a reaction rate of an order of magnitude greater than that of acetaldehyde for • OH (k b = 3 × 10 9 and 7.3 × 10 8 L mol −1 s −1 , respectively), 8 toluene is more resistant than acetaldehyde to photocatalytic mineralization with TiO 2 because of strongly adsorbed aromatic intermediates (e.g., quinones, benzaldehyde, benzyl alcohol, and benzoic acid).…”

“…Prolonged indoor activities increase exposure to indoor air pollutants. The extensive use of synthetic building materials, electronics, and household products causes severe indoor air pollution by releasing various volatile organic compounds (VOCs), such as acetaldehyde (CH 3 CHO) and toluene (C 7 H 8 ). , VOCs are responsible for sick building syndrome and multiple chemical sensitivities, causing several health issues (e.g., headaches, allergies, and nausea) . Among the existing indoor air purification technologies, photocatalysis is considered the most appropriate because of its operation under room temperature and atmospheric pressure without any auxiliary chemicals (e.g., O 3 and H 2 O 2 ) or expensive elements, and because it mineralizes pollutants into H 2 O and CO 2 by in situ generated hydroxyl radicals ( · OH). − …”

Performance and Mechanism of Chlorine Dioxide on BTEX Removal in Liquid and Indoor Air

“…Shim et al, modified the surface-wrinkled silica nanoparticles (WSNs) with organosilane, to adsorb gaseous BTEX. At room temperature, 50 mg of hexadecyltrimethoxysilane (HDTMS)-WSN can thoroughly remove 200 µg/m 3 of benzene, toluene, and xylene mixed air samples [13]. Sui et al, investigated the removal and recovery of o-xylene using silica gel and a vacuum swing adsorption (VSA) process.…”