Volatile organic compounds (VOCs) removal capacity of ZSM-5 zeolite adsorbents for near real-time BTEX detection

Abstract

The environmental impact of air pollution along with the registered detrimental effects on human health due to BTEX exposure have forced most countries to set limit values in public spaces and buildings, requiring the development of in situ devices able to quantify in (near)-real time the pollutants concentration, even at ppb levels. In this work, several ZSM-5 zeolites with 79 < Si / Al < 316 have been synthesized and used as part of a pre-concentration unit connected to a miniaturized GC prototype, needed to drop the detection limit according to current legislation. The most important parameters influencing the multicomponent gas-phase adsorption of BTEX over ZSM-5 zeolites have been found to be the number of available acid sites (Al content), the zeolite pore size and its hydrophobicity. The experimental results demonstrate that a compromise between the hydrophobic character and the number of Al atoms should be found in order to properly design an adsorbent for near-real time BTEX detection.