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7277670 
Journal Article 
Mechanistic insights into fast adsorption of perfluoroalkyl substances on carbonate-layered double hydroxides 
Chen, Y; Georgi, A; Zhang, W; Kopinke, FD; Yan, J; Saeidi, N; Li, J; Gu, M; Chen, M 
2020 
Yes 
Journal of Hazardous Materials
ISSN: 0304-3894
EISSN: 1873-3336 
408 
124815 
English 
33370694 
WOS:000620410900002 
Layered double hydroxide (LDH) with the metal composition of Cu(II)Mg(II)Fe(III) was prepared as an adsorbent for fast adsorption of perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA). 84% of PFOS and 48% of PFOA in relation to the equilibrium state were adsorbed in the first minutes of contact with 0.1 g/L of suspended µm-sized LDH particles. The adsorption mechanisms of PFOS and PFOA on the CuMgFe-LDH were interpreted. Hydrophobic interactions were primarily responsible for the adsorption of these compounds in accordance with the different adsorption affinities of long-chain (C8, Kd = 105 L/kg) and short-chain (C4, Kd = 102 L/kg) perfluorinated carboxylic acids. PFOA adsorption on CuMgFe-LDH was strongly suppressed under alkaline conditions while PFOS uptake was only slightly affected in the pH range from 4.3 to 10.7, indicating a significant role of electrostatic interactions for PFOA adsorption. The adsorption of PFOS and PFOA was rather insensitive to competition by monovalent anions. The previously reported 'memory effect' of calcined CuMgFe-LDH for sorption of organic anions was not confirmed in the present study. Spent CuMgFe-LDH could be easily regenerated by extraction with 50 vol% methanol in water within 1 h and maintained a high PFOS removal in subsequent usage cycles. 
LDHs; PFOS; PFOA; Adsorption kinetics; Adsorbent regeneration