UiO-66 Selective Enrichment Integrated with Thermal Desorption GC-MS for Detection of Benzene Homologues in Ambient Air

In this study, UiO-66 was selected as sorbent media packed in the tube to selectively enrich trace levels of benzene homologues such as benzene, toluene, and xylene (BTX) in ambient air prior to thermal desorption (TD)-GC-MS determination. A series of experiments were conducted to obtain the optimal TD conditions. The results indicated that the optimal TD parameters were as follows: desorption temperature of 180°C, desorption flow rate of 50 mL min−1, and desorption time of 30 min. Furthermore, the method based on UiO-66 enrichment integrated with TD-GC-MS for trace levels of BTX was successfully developed. It exhibited a good linearity (R2 > 0.99) in the range of 50–1000 ng, except for p, m-xylene in the range of 100–2000 ng, and achieved the recovery of 69.4–101.3%, and the relative standard deviation of 3.8–6.4%. The detection limits of BTX were 1.6–4.0 ng; according to 10 L of sampling volume, the method detection limits would be in the range of 0.16–0.40 µg m−3. Additionally, the method was successfully applied to determine BTX in indoor air and showed good selectivity and sensitivity. In summary, the findings in this work revealed that UiO-66 was an attractive adsorbent for selective enrichment trace levels of BTX compounds in ambient air, which was favorable for the subsequent detection by TD-GC-MS.

Emissions Characterization of Volatile Organic Compounds and Health Risk Assessment in Two Fresh Furniture

The emissions of volatile organic compounds (VOCs) from two common furniture products including a dressing stool and a bedside cabinet were measured in an environmental chamber. The VOCs were collected by Tenax-TA tubes and measured by thermal desorption and gas chromatography (FID). 19 kinds of VOCs were quantitatively analyzed by the external standard method. The results showed that the VOCs concentrations emitted from the two kinds of furniture were quite different, but benzene homologues were the principal pollutant. The concentrations of VOCs released from the furniture showed decreases exponentially with time and it could be fitted well by a double-exponential decay model. The concentrations of VOCs increased rapidly and reached the maximums at around 1 or 2 h, and then declined with the slowdown of the release rate. Moreover, the potential VOCs release could be evaluated by the release parameters of this model. In addition, health risk assessment of benzene released from dressing stools and bedside cabinets was performed. The risk of benzene released from two kinds of furniture decreased with time. The R value of benzene released from the dressing stool at 72 h remained at least two orders of magnitude larger than 1 × 10−6, indicating a high risk of carcinogenesis. The study will provide a reliable reference in assessing VOCs emissions and health risks in fresh furniture.

Perylene Diimide-Based Fluorescent and Colorimetric Sensors for Environmental Detection

Perylene tetracarboxylic diimide (PDI) and its derivatives exhibit excellent thermal, chemical and optical stability, strong electron affinity, strong visible-light absorption and unique fluorescence on/off features. The combination of these features makes PDIs ideal molecular frameworks for development in a broad range of sensors for detecting environmental pollutants such as heavy metal ions (e.g., Cu2+, Cd2+, Hg2+, Pd2+, etc.), inorganic anions (e.g., F−, ClO4−, PO4−, etc.), as well as poisonous organic compounds such as nitriles, amines, nitroaromatics, benzene homologues, etc. In this review, we provide a comprehensive overview of the recent advance in research and development of PDI-based fluorescent sensors, as well as related colorimetric and multi-mode sensor systems, for environmental detection in aqueous, organic or mixed solutions. The molecular design of PDIs and structural optimization of the sensor system (regarding both sensitivity and selectivity) in response to varying analytes are discussed in detail. At the end, a perspective summary is provided covering both the key challenges and potential solutions for the future development of PDI-based optical sensors.

Supramolecular recognition of benzene homologues in a 2D coordination polymer through variable inter-layer π–π interaction

A 2D network 1 was synthesized. After immersing 1 in benzene homologues, the crystal structures of 2 and 3 were gotten, demonstrating that the introduction of benzene homologues has transformed the π–π packing mode, further altering the host framework and fluorescence performance.