Adsorption of hydrophilic and hydrophobic pharmaceuticals on RO/NF membranes: Identification of interactions using FTIR

Abstract

This article examines the adsorption of pharmaceuticals on reverse osmosis (RO) and nanofiltration (NF) membranes. The membranes were characterized in terms of Fourier transformation infrared (FTIR) spectra, surface charge, hydrophobicity, pore size distribution, and roughness. Five pharmaceuticals were used to determine their rejection and possible interactions with the membranes. Albendazole, a hydrophobic pharmaceutical, adsorbed on the NF (NF270) and RO (XLE) membranes. FTIR spectra showed significant changes (new peaks/bonds) on the membranes, confirming that adsorption plays an important role in the overall mechanism of rejection in the case of hydrophobic compounds. Hydrophilic pharmaceuticals (sulfaguanidine, trimethoprim, hydrocortisone, and procaine) did not adsorb on the XLE membrane, showing that size exclusion and electrostatic repulsion were both dominant removal mechanisms. This article gives new insights into NF membranes in the treatment of hydrophilic compounds. The results clearly show the adsorption of hydrophilic compounds on the NF membranes since H‐bonds and π–π interactions were observed on their FTIR spectra. Therefore, both the hydrophobic and the hydrophilic adsorption have to be taken into account when considering the removal mechanism, especially in the case of NF membranes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44426.

The role of interaction between low molecular weight neutral organic compounds and a polyamide RO membrane in the rejection mechanism

“…Stronger interactions between an organic compound and the membrane (i.e., more negative DG intr aq,calc ) generally led to a higher partitioning of the organic compound into the membrane matrix because of the relationship in eqn (3). Furthermore, the higher partitioning of an organic compound into the membrane matrix led to a lower rejection of the organic compound, 12,13 and larger k s values were thus observed. Accordingly, the negative slopes observed in Fig.…”

“…In general, strong interactions between organic compounds and membranes are dominant for the mass transfer of small molecules from water to membranes 11 and increase the concentration of the solute within the membrane, which decreases the rejection efficiency. 12,13 Three major solutesolvent-membrane interactions that have been distinguished are (1) steric exclusion, (2) electrostatic interactions, and (3) an affinity between the solute and membrane. 12,14,15 The affinity component includes hydrophobic attraction, hydrogen bonding, and the dielectric effect of water molecules and is described by the free energy of interaction between the solute and the membrane in the aqueous phase.…”

Recent Advances in the Rejection of Endocrine-Disrupting Compounds from Water Using Membrane and Membrane Bioreactor Technologies: A Review

“…Also, the neutral/uncharged EDCs contaminants are typically removed by size hindrance mechanism [ 181 , 182 ], the connection between EDCs contaminants and hydrophobicity rejection assessed as Octanol-water partition coefficient −LogK ow ) in addition to membrane pure water permeability flux is frequently reported as necessary, exhibiting elevated removal rate for more hydrophobic EDCs, especially in conditions where hydrophobic adsorption removal mechanism is influential [ 147 ]. While the impact of water solubility on the rejection is reported to be more insignificant, some other studies indicate that water solubility of a compound should be evaluated as the first investigative parameter on its movement in NF membrane separation as experimentations reveal that neutral (uncharged) compounds with low water solubility, lower molecular weight (Mw), and strong hydrophobicity (high LogK ow values) were rejected better than others with relatively higher water solubility and higher Mw [ 181 ].…”

Removal of Trimethoprim from Water using Carbonized Wood Waste as Adsorbents

“…The researchers are working to develop technologies [14] and strategies [15,16,17,18] to remove various forms of pollutants and contaminants, including pharmaceuticals from water. Recently the most sustainable technology so far developed was adsorption process [19,20,21,22,23,24,25].…”