Removal of nonsteroidal anti-inflammatory drugs (NSAIDs) by electrocoagulation-flotation with a cationic surfactant

An electrocoagulation flotation (ECF) process was used to remove selected nonsteroidal anti-inflammatory drugs (NSAIDs), specifically diclofenac, ibuprofen, and ketoprofen, from water. A cationic surfactant, cethyltrimethyl ammonium bromide (CTAB), was added to the solution as a collector and frother. Without the addition of the cationic surfactant, the removal of NSAIDs in a single-NSAID solution was in the range of 10-45%; it decreased to approximately 10% in multiple-NSAID systems. However, after adding a stoichiometric amount of CTAB, the removal of NSAIDs significantly improved in single-NSAID systems. For multiple-NSAID removal, the concentration of CTAB required to achieve ideal removal was equal to the sum of the molar concentrations of all the NSAIDs. In addition, a high current density produced smaller bubbles, thus enhanced the electro-flotation and achieved better removal performance. Removal of multiple-NSAIDs in actual hospital wastewater was significantly lower due to interference by oils and other hydrophobic substances.