Environmental protection by the adsorptive elimination of acetaminophen from water: A comprehensive review

Acetaminophen (ACT) is an effective and widely available analgesic and antipyretic used in medical practice. It can get into water from veterinary use, medical waste and pharmaceutical effluents. The aim of this review was to elaborate on the recent progress on ACT adsorption from water, present the findings in a structured written report and identify interesting new foundations for further work. ZnAl/biochar had the highest potential of removing ACT and can adsorb more than its weight of the pollutant (q_max > 1000 mg/g). The Langmuir and Freundlich isotherm models and the pseudo-second-order kinetics model were best-fits in most cases (usually at R² > 0.99 threshold). It was observed that the key mechanisms of ACT uptake are π-π interactions, hydrogen bonds and electrostatic interaction. For most of the adsorbents, a >30% ACT removal efficiency was achievable after the 4 cycles. Effects as salting-out, electrostatic screening, and accumulation of moieties at sorbent-sorbate interfaces due to the competitive adsorption of ions and co-pollutants are profound in the uptake of ACT from aqueous solutions. Future perspectives were discussed in the area of process costing, adsorbent regeneration, mechanistic investigations and fixed-bed column adsorption.