Water pollution has intensified in recent years, with pharmaceutical residues emerging as critical contaminants of global concern. Commonly detected in rivers, lakes, and even drinking water, these compounds pose serious ecological and health risks, including embryotoxicity, oxidative stress, antimicrobial resistance, and cardiovascular dysfunction. Conventional wastewater treatments are often ineffective in eliminating such micropollutants, which has motivated the exploration of advanced and sustainable remediation methods. Among these, adsorption is considered one of the most reliable and efficient approaches, with activated carbon widely recognized as the benchmark adsorbent in water treatment applications.
In this study, we evaluate the adsorption efficiency of three widely used pharmaceuticals, ofloxacin, ceftriaxone, and metformin, which are mainly excreted in unmetabolized form and frequently reported in aquatic environments. Batch adsorption experiments were performed at an initial pollutant concentration of 50 mg/L, in the presence of activated carbon, while investigating the effects of adsorbent dosage, initial concentration, and pH conditions. Results demonstrated that the antibiotics achieved removal efficiencies exceeding 90% at neutral pH values. In contrast, metformin adsorption was negligible under the same conditions but increased significantly in acidic media, consistent with its structural and ionization characteristics.
Adsorption data for ceftriaxone and ofloxacin fitted the Langmuir isotherm model with high correlation coefficients (R2 = 0.983 and 0.986, respectively), confirming a monolayer adsorption process. These findings clarify the contrasting adsorption behaviors of antibiotics and antidiabetic drugs, emphasize the importance of optimizing operational parameters, and provide valuable insights into the mechanisms governing pharmaceutical adsorption on activated carbon.
