Removal of acetaminophen by activated carbon synthesized from spent tea leaves: equilibrium, kinetics and thermodynamics studies

Abstract

Recently, pharmaceutical compounds have been identified as Contaminants of Emerging Concern (CEC) in wastewater due to the potential hazards to human bodies, and various methods are being developed to remove CEC from wastewater and water bodies. This research reports conversion of spent tea leaves (STL) to activated carbon (AC) for removal of acetaminophen (paracetamol) from simulated wastewater. STL-AC prepared via phosphoric acid activation (STL-ACH) showed the highest adsorption performance towards acetaminophen when compared to STL-AC activated by other chemicals. Characterizations on STL-ACH revealed that acid treatment led to dehydration and chemical reactions in the biomass precursor. The maximum removal efficiency of aspirin observed at the initial concentration of 10 mg/L, adsorbent dose of 0.5 g, pH 3 at room temperature and reaction time of 60 min. The adsorption data were well fitted to the Langmuir isotherm model and obeyed the pseudo-second order kinetics model. The adsorption capacity of STL-ACH towards acetaminophen was found to be 59.2 mg/g. The adsorption process is exothermic, feasible and spontaneous according to the thermodynamic evaluation. This study demonstrates the feasibility to convert one common biowaste to a value-added product that removes contaminants of emerging concern (CEC) from wastewater, thus it is necessary to investigate the potential of STL-ACH in wastewater treatment application.