Structured carbon fiber cloth-templated ZIF-8 by binder-free method for efficient dyes removal from water

Abstract Organic dyes pollution of contaminated water is posing serious environmental crisis. In this work, the robust absorbent of organic dyes has been proposed by using carboxyl-modified carbon fiber (CF) cloths as scaffolds to structure ZIF-8 powder with specific shape (area: 10 × 10 cm2 and thickness: 2 mm). The grinding ZnO and 2-methylimidazole powder was deposited on –COOH groups functionalized CF-cloth via an in situ non-solvent synthesis process without using binder. This as-synthesized robust absorbent was assembled layer-by-layer with four folds of ZIF-8 layers by inserting three folds of CF (3k, T300) between ZIF-8 layers. The surface microstructure of ZIF-8 and robust absorbent has been investigated and compared by X-ray diffraction. The techniques including Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS), and X-ray photoelectron spectroscopy (XPS) have been proposed to confirm the interfacial adhesion and surface modification of CF cloths layers in robust adsorbent. Moreover, compared to ZIF-8, CF-ZIF-8 composite exhibited improved thermal stability by the thermal gravimetric (TG) analysis. The CF-ZIF-8 composite exhibited two types of adsorption curves by using UV absorption spectra, which could discriminate six kinds of organic dyes by charge effect. The UV absorption of MB(Methylene Blue), CV(Crystal Violet) and TB(Toluidine Blue) dropped dramatically and exhibited only 4.5%, while the UV absorption of RB19 (Reactive Blue 19), RhB (Rhodamine B) and MO (Methyl Orange) exhibited 58.2%, 58.3% and 70.0% of original absorption intensity after conducted adsorption processes of 700 min, respectively. The as-synthesized robust adsorbent would be easily adapted and recycled from wasted water of real industry fields, which may attract more attentions to build the bridge between MOFs powder materials to carbon fiber cloth for real use.