Copper 2-Methylimidazole Nanostructure-Based Colorimetric Fabric Sensor for Real-Time Monitoring of Ambient Sulfur Oxides

Abstract

For effective protection from exposure to hazardous gases, a facile strategy of real-time gas monitoring is highly needed. In this study, a novel colorimetric indicator that allows the visual detection of ambient sulfur oxides (SO x ) is developed, applying copper 2-methylimidazole [Cu(mIm)] nanocrystals to a cellulose fabric. By optimization of the molar ratio of copper to mIm, the properties of the treated fabric are improved for the Cu(mIm) loading capacity, gas adsorption performance, and colorimetric response. It is revealed that the role of environmental humidity is crucial for effective adsorption and chromatic reaction of Cu(mIm) because the hydrated Cu(mIm) surface facilitates SO 2 adsorption, producing reactive species of HSO 3 − or SO 4 2−. Those reactive SO x species cause the structural transformation of Cu(mIm) and ultimately lead to a chromatic response. The chromatic reaction takes place close to the breakthrough concentration of 5 ppm, demonstrating that the Cu(mIm) fabric can be applied as a practical service-life indicator, timely signaling the replacement time of protective materials. It is anticipated that the proposed strategy offers an effective SO x monitoring solution for application in various fields that call for facile gas detection.

Cooperative Design of the Ag3PO4/NH2-MIL-88B (Fe/Co) Heterojunction Integrated with Conductive Polypyrrole for Advanced Photocatalytic Water Purification

“…With the growing concerns about aggravating water pollution, research efforts have been made on the development of efficient purification methods; particularly, a photocatalytic system applying metal–organic frameworks (MOFs) has drawn focused attention during the past decade. − MOFs consist of metal clusters linked with organic ligands, forming highly porous crystals, and have been explored for various applications with their advantages of high surface area, chemical tolerability, and suitable band energy as practical photocatalysts. − MOF-based photocatalysts have been developed in various composite forms including films, fibers, and foams, as the photocatalyst itself in the powdery form is inconvenient to recover after use and can cause secondary pollution. − Among the composite forms, the fibrous MOF composite can be especially advantageous for its flexibility, toughness, and large surface area that allows high loading of MOFs. − However, the higher loading of photocatalysts does not ensure efficient catalytic performance, that is, as most MOFs and fiber matrices have lower electrical conductivity, they tend to produce a low quantum yield. , Many research efforts have been made to overcome this drawback, conceiving a heterojunction system or imparting electrical conductivity. , …”

Heterostructured Photocatalytic Fabric Composed of Ag3PO4 Nanoparticle-Decorated NH2-MIL-88B (Co/Fe) Crystalline Wires for Rhodamine B Adsorption and Degradation

“…The environmental impact of dye wastewater caused by various industries is escalating, and there are urgent demands for effective treatment to minimize adverse impacts on the environment. − Given the gravity of this issue, enormous attention is being directed toward water remediation technologies including membrane filtration, electrochemical treatment, adsorption, and photocatalysis. − Adsorption technology stands out as a preferred method among those approaches, owing to its effectiveness and the simplicity of the process. − However, commercial adsorbents like activated carbon are used mostly as disposables or require a high-pressure stream for regeneration of the activated carbon, which makes them relatively costly in terms of repeated usability. , …”