Composite super-adsorbents of chitosan/activated carbon for the removal of nonsteroidal anti-inflammatory drug from wastewaters

Abstract

Pharmaceutical residues in wastewater are an environmental concern with implications on human health and aquatic ecosystems. To solve this problem, this study proposes a more sustainable approach using chitosan-based adsorbents combined with activated carbon (AC) for the removal of pharmaceutical waste from wastewater. Chitosan (Cs), a biodegradable polysaccharide, offers unique properties for contaminant adsorption and activated carbon offers a large specific surface area. The synergistic effect of these two super-absorbents is examined for the removal of diclofenac, a widely used drug. The effectiveness of these adsorbents was evaluated, considering factors such as pH, contact time, and temperature. The results showed that Cs/AC beads with a 2:1 ratio had the highest adsorption capacity (165.33 mg/g at 323 K), the results fitted better to Langmuir model, and adsorption followed a pseudo-second-order kinetic model. Thermodynamic analysis indicated that the adsorption process was chemisorption, with a strong interaction between diclofenac and adsorbents. Regeneration studies showed that Cs/AC composites can be regenerated up to ten cycles, showing a small reduction in their efficiency. Overall, the chitosan/activated carbon approach shows promising prospects as an effective and environmentally friendly method for the removal of pharmaceutical residues from wastewater.