Clay minerals for the removal of pharmaceuticals: Initial investigations of their adsorption properties in real wastewater effluents

Abstract

The adsorption of pharmaceutical products (PPs) onto kaolinite and raw and sodium-exchanged montmorillonite was investigated in real wastewater effluents (WWE). The important role of the charge state of the PPs in controlling the adsorption extent was highlighted. Whereas cationic PPs were mostly adsorbed through cation exchange, the adsorption of neutral and anionic PPs appeared to be controlled by the nature of compensating inorganic cations and/or the simultaneous adsorption of organic moieties onto clay minerals. In raw WWE, the concentration of PPs is indeed far lower than the concentration of other organic molecules. Among the adsorbents tested, kaolinite displayed the lowest adsorption capacity of both PPs and other organic molecules, compared to raw montmorillonite which presented the highest adsorption capacity. The sodium-exchanged montmorillonite displayed intermediate adsorption properties, highlighting the key role of divalent inorganic cations in the adsorption of non-cationic PPs and other organic molecules. Hence, raw 2 montmorillonite appears to be the most promising adsorbent for further investigations aiming to test the practicability of a clay-based adsorbent for the removal of organic contaminants, such as PPs, in WWE.

Removal of Pharmaceuticals from Water by Adsorption and Advanced Oxidation Processes: State of the Art and Trends

“…However, clay minerals could be inexpensive and widely available materials for the removal of pharmaceuticals [82]. For clay materials, the most common types (illite, kaolinite, vermiculite, montmo-rillonite, bentonite, and sepiolite) have already been used for the removal of a variety of organic micro-pollutants.…”

“…For clay materials, the most common types (illite, kaolinite, vermiculite, montmo-rillonite, bentonite, and sepiolite) have already been used for the removal of a variety of organic micro-pollutants. Montmorillonite is the most promising adsorbent for further investigations aimed at testing the practicability of a clay-based adsorbent for the removal of pharmaceuticals compounds [82]. The use of natural clay (montmorillonite (Mt), vermiculite (VER), bentonite (B), kaolinite (K)) and modified clay-based sorbents commercial acid-activated montmorillonites K10 and K30, and two carbonaceous-mineral nanocomposites (MtG5%T, BAlG3%C) for the removal of ibuprofen, diclofenac, ketoprofen, carbamazepine, bisphenol A, and triclosan, showed that vermiculite was the best adsorbent for the removal of all drugs.…”

Carbamazepine Removal by Clay-Based Materials Using Adsorption and Photodegradation

“…Adsorption of carbamazepine on various clays was examined in several studies. Adsorption studies on montmorillonite are inconclusive, while some studies present poor-to-low adsorption capacities (0-0.02 mmol g −1 ) [35][36][37][38] and others report considerably higher values (up to 0.15 mmol g −1 ) [39,40]. Most studies have ascribed adsorption of CBZ on montmorillonite to Van der Waals interactions between the aromatic rings and the clay surface, and hydrogen bonds coordinating between oxygen atoms and exchangeable cations [36,38,40].…”

Pharmaceuticals Removal by Adsorption with Montmorillonite Nanoclay

“…To ease the recovery of used adsorbents, they can be made responsive to an applied magnetic field, as it was successfully demonstrated with carbon nanotubes impregnated with a metal phase [ 27 ]. Adsorbents based on clay minerals [ 28 ] have also been considered as readily available natural materials that can be used to remove organic micropollutants [ 29 , 30 , 31 ].…”