Airborne Toluene Detection Using Metal–Organic Frameworks

Abstract

The pollution of indoor air is a major worldwide concern in our modern society for people's comfort, health, and safety. In particular, toluene, present in many substances including paints, thinners, candles, leathers, cosmetics, inks, and glues, affects the human health even at very low concentrations throughout its action on the central nervous system. Its prevalence in many workplace environments can fluctuate considerably, which led to firm regulation with exposure limits varying between 50 and 400 ppm depending on exposure time. This therefore requires the development of technologies for an accurate detection of this contaminant. Metal−organic frameworks have been proposed as promising candidates to detect and monitor a series of molecules at even extremely low concentrations owing to the high tunability of their functionality. Herein, a high-throughput Monte Carlo screening approach was devised to identify the best MOFs from the computation-ready, experimental (CoRE) metal−organic framework (MOF) density-derived electrostatic and chemical (DDEC) database for the selective capture of toluene from air at room temperature, with the consideration of a ternary mixture composed of extremely low-level concentration of toluene (10 ppm) in oxygen and nitrogen to mimic the composition of air. An aluminum MOF, DUT-4, with channel-like micropores was identified as an excellent candidate for the selective adsorption of toluene from air with a predicted adsorption uptake of 0.5 g/g at 10 ppm concentration and room temperature. The toluene adsorption behavior of DUT-4 at low equivalent concentrations, alongside its sensing performance, was further experimentally investigated by its incorporation in a quartz crystal microbalance sensor, confirming the promises of DUT-4. Decisively, the resulting high sensitivity and fast kinetics of our developed sensor highlight the applicability of this hand-in-hand computational−experimental methodology to porous material screening for sensing applications.

MIL-101(Cr)@QCM and MIL-101(Cr)@IDE as Sorbent-Based Humidity Sensors for Indoor Air Monitoring

“…In the latter case, the resistance ( R ) and capacitance ( C ) of the bulk solid were determined by applying a fitting procedure to the Nyquist plots of the impedance, with equivalent circuits using EIS Spectrum Analyzer 1.0 Software . For sensing experiments recorded under a toluene atmosphere, the DVS apparatus was upgraded to reach vapor traces of the sorbate consistent with concentrations encountered in indoor environments, i.e., around a few parts per million levels …”

“…37 For sensing experiments recorded under a toluene atmosphere, the DVS apparatus was upgraded to reach vapor traces of the sorbate consistent with concentrations encountered in indoor environments, i.e., around a few parts per million levels. 38…”

High-Throughput Computational Screening and Machine Learning Model for Accelerated Metal–Organic Frameworks Discovery in Toluene Vapor Adsorption

“…These techniques also allow methane adsorption and identification of property–performance trends, resulting in bottom-up design guidelines for new MOFs toward top-performance directional selection. Moreover, some studies have proceeded to investigate the detection of airborne toluene traces . However, to the best of our knowledge, only a few data-driven screening or material design studies of MOFs for disposing of VOCs, mainly toluene vapor, using theoretical methods and employing HTC have been reported.…”

“…Moreover, some studies have proceeded to investigate the detection of airborne toluene traces. 44 However, to the best of our knowledge, only a few data-driven screening or material design studies of MOFs for disposing of VOCs, mainly toluene vapor, using theoretical methods and employing HTC have been reported.…”

Deep Photocatalytic Oxidation of Aromatic VOCs on ZnSn LDH: Promoting Role of Electron Enrichment of Surface Hydroxyl

“…Aromatic volatile organic compounds (VOCs), including toluene, styrene, and chlorobenzene, are one of the most ubiquitous and refractory pollutants in indoor environments, with an extremely low toxicity threshold and a serious threat to human health . In recent years, stricter policies were enacted to limit indoor aromatic VOCs under the great attention of the public and government . Numerous techniques have been investigated to effectively eliminate toluene.…”