Removal Efficiency And Adsorption Kinetics Of Perfluorohexanoic Acid By Mgal-Carbonate Layered Double Hydroxide And Its Calcined Products

In this study, perfluorohexanoic acid (PFHxA) was presented as pollutant in water and magnesium-aluminum-carbonate layered double hydroxide (MgAl-LDH) as well as its calcined product (CLDH) were presented as sorbents. The physical and chemical properties of as-prepared MgAl-LDH and CLDH were examined by Fourier transform infrared (FT-IR) analysis, X-ray diffraction analysis, Brunauer-Emmett-Teller (BET) analysis and X-ray photoelectron spectroscopy analysis. The FT-IR results indicated that the as-prepared samples are the desired products and the structure of CLDH has recovered after adsorption of PFHxA. The X-ray diffraction (XRD) analysis confirmed that the synthesized products have well-ordered layer structure and PFHxA can be removed from aqueous solution through entering interlayer of CLDH. The BET analysis verified the surface areas and pore size distributions of MgAl-LDH and CLDH, respectively. The X-ray photoelectron spectroscopy (XPS) analysis further proved the adsorption mechanism via element changes between CLDH before and after adsorption. For the adsorption experiment, the effects of the adsorption conditions including calcination, dosage, temperature and duration of oscillation have been investigated. The best removal efficiency of PFHxA by CLDH is 89.54%, which is provided by 0.1 g CLDH at 65 degrees C for 30 min in 30 mL PFHxA solution with initial concentration of 0.3592 g/L. The adsorption kinetics of PFHxA by CLDH was studied. The kinetic data were well-fitted to the pseudo-first-order kinetic model. Based on FT-IR and kinetic analysis, the "memory effect" may play an important role in adsorption stage. Since CLDH show excellent removal efficiency of PFHxA, they are expected to separate PFHxA from water in pollution control.