Magnetically recyclable core–shell MOF nanoparticles of Fe3O4@PDA@UIO-66-NH2 grafted by organic acids for intensified cationic dye adsorption. (24th May 2022)

• Record Type: Journal Article
• Authors: Fu, Yujia; Xu, Yue; Lou, Boxuan; Qin, Xiaolan; Zhang, Leilei; Yuan, Haikuan; Zhang, Lijuan; Zhang, Yan; Lu, Jie
• Is Part Of: New journal of chemistry. Volume 46:Number 23(2022)
• Page Start: 11071
• Page End: 11081
• Publication Date: 2022-05-24
• Subjects: Chemistry -- Periodicals; Chimie -- Périodiques; 540
• DOI: 10.1039/d2nj01748b
• Languages: English
• ISSNs: 1144-0546

Abstract

Abstract : The adsorption mechanism towards MB by the two adsorbents is mainly due to IE at lower solution pH and EA at higher solution pH than their pHpzc . Abstract : Two kinds of hierarchical magnetic metal–organic framework (MOF) nanoparticles Fe3 O4 @PDA@UIO-66-NH-tar (mUIO-66-NH-tar) and Fe3 O4 @PDA@UIO-66-NH-citr (mUIO-66-NH-citr) were fabricated through post-synthetic modification. The novel nanoparticles were then characterized using SEM, FTIR, PXRD, XPS and surface area analysis. Owing to the porous structure and the high density of the carboxylic acid group (primary sorption sites), the as-prepared adsorbents demonstrated a very fast adsorption rate and a much higher adsorption capacity of methylene blue (MB, as a model of cationic dyes) from aqueous solutions in an expanded pH range. The highest adsorption capacities of mUIO-66-NH-tar and mUIO-66-NH-citr were 381.7 and 432.9 mg g −1, respectively. Experimental results indicated that the pseudo-second order rate equation and Langmuir isotherm model described the kinetics and adsorption isotherm of MB accurately. At higher solution pH (pH > pHpzc of adsorbents), the adsorption of MB by the two adsorbents was mainly driven by electrostatic attraction (EA), hydrogen bonding (HB) and π–π stacking, whereas cation exchange might be the predominant adsorption mechanism at lower solution pH (pH < pHpzc of adsorbents). Moreover, both as-prepared nanoparticles were observed to have high reusability, which could be used over six adsorption–desorption cycles without significant capacity loss.