Preparation of Nanofibrous Metal–Organic Framework Filters for Efficient Air Pollution Control

TLDR

Air pollution, including particulate matter and toxic gases, poses serious global health threats, and metal‑organic frameworks offer high porosity and tunable pore sizes that could capture such pollutants. For the first time, the interactions between porous crystalline MOFs and particulate pollutants were explored. Nanocrystals of four distinct MOF structures were processed into nanofibrous filters (MOFilter) with up to 60 wt % MOF loading. The MOFilters achieved PM2.5 and PM10 removal efficiencies of 88.33 % and 89.67 %, respectively, maintained over 48 h of continuous filtration, and also selectively captured SO₂ from an SO₂/N₂ mixture while allowing high‑flow fresh air with a pressure drop below 20 Pa.

Abstract

Environmental challenges especially air pollution (particulate matter (PM) and toxic gases) pose serious threats to public health globally. Metal-organic frameworks (MOFs) are crystalline materials with high porosity, tunable pore size, and rich functionalities, holding the promise for poisonous pollutants capture. Here, nanocrystals of four unique MOF structures are processed into nanofibrous filters (noted as MOFilter) with high MOF loadings (up to 60 wt %). The MOFilters show high PM removal efficiencies up to 88.33 ± 1.52% and 89.67 ± 1.33% for PM2.5 and PM10, respectively, in the hazy environment, and the performance remains largely unchanged over 48 h of continuous filtration. For the first time, the interactions between such porous crystalline material and particulate pollutants were explored. These thin MOFilters can further selectively capture and retain SO2 when exposed to a stream of SO2/N2 mixture, and their hierarchical nanostructures can easily permeate fresh air at high gas flow rate with the pressure drop <20 Pa.