Abstract:
Pharmaceutical compounds including non-steroidal anti-inflammatory drugs such as mefenamic acid and naproxen are increasingly detected in water bodies globally, raising serious concerns about their ecological and public health impacts. Conventional wastewater treatment systems are largely ineffective at removing these micropollutants from water sources. This study designed and evaluated a simple gravity-driven granular activated carbon fixed-bed adsorption column for the removal of mefenamic acid and naproxen from synthetic aqueous solutions. The column was constructed from a plastic syringe packed with layers of cotton, gravel, silica sand, and GAC with dimensions of 1 cm gravel, 4 cm sand, and 4 cm GAC respectively. Stock solutions of 1000 mg/L were prepared from pharmaceutical tablets and diluted to working concentrations of 5 mg/L, 25 mg/L, and 50 mg/L. The effects of initial concentration, solution pH (acidic and basic conditions), contact time, and water matrix type (distilled and tap water) on removal efficiency were systematically investigated. All samples were analyzed by UV-Visible spectrophotometry at 270 nm. The column achieved a maximum removal efficiency of 97.1% for mefenamic acid at 50 mg/L in distilled water. Removal efficiency increased with higher initial concentration and longer contact time for both pharmaceutical compounds. Mefenamic acid showed preferential removal under acidic conditions while naproxen performed marginally better under basic conditions above its pKa charge state. Tap water experiments showed reduced removal efficiency compared to distilled water due to competitive adsorption by dissolved matrix substances. Mefenamic acid consistently outperformed naproxen under all experimental conditions due to its higher hydrophobicity and stronger affinity for the activated carbon surface. The findings contribute to SDG 6 and SDG 3 by demonstrating the technical feasibility of a low-cost, electricityfree approach to pharmaceutical water treatment
