Investigation of Diclofenac Removal From Aqueous Solutions Using NH4Cl-Induced Activated Carbon

Background Painkillers such as diclofenac are widely used in human medicine and veterinary medicine. Because of their excretion into water resources and subsequent environmental hazards, their removal from the waters and wastewaters is essential. Since, these drugs cannot undergo biodegradation, an advanced treatment such as adsorption method must be applied for their removal and one of the best adsorbents in this regard is activated carbon. This study aimed to investigate the removal of diclofenac contaminant by NH4Cl-induced activated carbon.
Materials & Methods Activated carbon produced from agricultural wastes was impregnated with ammonium chloride (NH4Cl) and activated at 800°C. The experiments were conducted in a closed system using a magnet stirrer at 100 rpm. In this investigation, the effects of several variables, namely adsorbent concentration, contact time, pH, and temperature, on the removal of diclofenac were evaluated. Then, isotherms and adsorption thermodynamic were explored. We used DR 5000 spectrophotometer model for drug analysis with the wavelength of 275 nm.
Results The produced NAC (NH4Cl-induced activated carbon), having the special surface of 1029 m2/g and pores volume of 2.46 nm, was able to remove 0.81% of diclofenac from a solution of 50 mg/L at the sorbent concentration of 0.8 mg/L, pH 6, in 20 minutes time. The equilibrium adsorption experiments showed that the absorption of diclofenac on NAC followed the Longmuir model and the absorption capacity was 212.5 mg/g. Using the diclofenac concentration of 50 mg/L and other optimal conditions, thermodynamic studies of diclofenac absorption on NAC showed that the amount of drug removal increased from 73% to 95% with increasing temperature from 10°C to 40°C.
Conclusion NAC can be used as a convenient and inexpensive adsorbent for the removal of diclofenac and other drug compounds from polluted waters and wastewaters.