Adsorption of nonsteroidal anti-inflammatory drugs onto composite beads of a 1D flexible framework MIL-53(Al): Adsorption mechanisms and fixed-bed study

The adsorption mechanisms of three nonsteroidal anti-inflammatory drugs (NSAIDs), ibuprofen (IBP), ketoprofen (KET), and naproxen (NPX), applied onto a pristine 1D flexible framework MIL-53(Al) were compared with those adsorbed on MIL-53(Al)/alginate (AM) and polyvinylidene fluoride/MIL-53(Al) (PM) composite beads through investigation of single-solute batch and fixed-bed systems. The 1D flexible framework of pristine MIL-53(Al) exhibited outstanding adsorption capacities for the three NSAIDs (IBP > NPX > KET) in comparison to powdered activated carbon via an increase in pore diffusion through the 1D framework supported by the breathing effect phenomena. The MIL-53(Al)/alginate at 3:25 w/w (AM25) exhibited better adsorption capacities for the three NSAIDs than the composite beads with higher MIL-53(Al) ratios (3:50 and 3:75 w/w). However, the adsorption of the three NSAIDs on AM25 was 2.2–5.5-times lower than that of the pristine MIL-53(Al). The dominant interactions of IBP between MIL-53(Al) were hydrogen bonding between the Al–OH(OH2) node of MIL-53(Al), the carboxylic groups of IBP, and the carboxylic group of terephthalic acid of MIL-53(Al). AM25 exhibited high selectivity for IBP against the background matrix of wastewater obtained from a hospital, and it could be applied at a low concentration range (μg/L). An increase in the empty bed contact time (38.7 min to 96.9 min) of fixed-bed systems for the adsorption of IBP on AM25 could improve the usage rate and fractional bed utilization; moreover, the breakthrough removal percentage was increased up to 98.1%. The multi-layer log-Thomas model can be fitted well for all breakthrough curves.