Sorption of pharmaceutical compounds and nutrients by various porous low cost adsorbents

In this study, the potential of eight low cost and readily available materials as adsorbents for the removal of pharmaceutically active compounds (carbamazepine (CBZ), diclofenac (DCF) and ibuprofen (IBU)) and nutrients was evaluated through batch studies under various environmental conditions. Results showed that wood charcoal, light-weight expanded clay aggregate (LECA), natural zeolites and waste AAC blocks has a potential as promising adsorbents for the elimination of micro-pollutants with the sorption capacity of 0.57-2.83 mg/g for the selected compounds due to their superior properties including higher surface area, pore volume and organic content. Studies revealed that hydrogen bonding, electrostatic and ligand interaction and Vander Waals force are the predominant mechanisms responsible for the sorption process. The selected materials exhibited better removal of phosphate (70-90%) than ammonia (20-81%) and nitrate (14.1-61.8%). Surface area, pore volume, organic content, cation exchange capacity and elemental content (CaO, Al2O3, K2O and Fe2O3) significantly influenced the pollutant removal by the substrates. Being hydrophobic and anionic in nature, DCF exhibited higher removal than IBU and CBZ. Based on the results, the order of preference of material as adsorbent is: wood charcoal > natural zeolite > waste AAC blocks > LECA > blast furnace slag > natural pyrite > brickbats > sand. The results of this batch study will be helpful for selecting appropriate substrate material for the low-cost natural treatment systems where the bio-enhanced sorption/degradation processes help to eliminate the toxic emerging contaminants (ECs) from wastewater.

Automated summary

This study evaluated the potential of eight low-cost materials as adsorbents for the removal of pharmaceutically active compounds and nutrients. The results showed that wood charcoal, LECA, natural zeolites, and waste AAC blocks have a promising potential for the elimination of micro-pollutants due to their superior properties. The mechanisms responsible for the sorption process were identified and the results will aid in selecting appropriate substrate materials for low-cost natural treatment systems.