Performance of organoclay in adsorptive uptake of antihypertensive losartan potassium: A comparative batch study using micro-grain activated carbon

[Display omitted] •98% of losartan can be removed by adsorption over Spectrogel commercial organoclay.•Spectrogel is more effective than micro-grain activated carbon for losartan uptake.•Kinetics obeys pseudo-second order model and equilibrium follows Freundlich model.•Surface chemistry is more important than surface features in losartan adsorption.•Losartan uptake by Spectrogel is controlled by adsorption and partition mechanisms. The antihypertensive losartan potassium is an emerging pharmaceutical contaminant that has been traced in aquatic media; hence, up-to-date water treatment methods are urged. This paper is the first of its kind to examine losartan uptake by adsorption using an organophilic clay, Spectrogel. In comparison, a micro-grain activated carbon (μGAC) was employed. Adsorption kinetics, isotherms and thermodynamics were examined and characterizations were performed. Pseudo-first order, pseudo-second order, external diffusion, surface diffusion and pore diffusion models were adjusted to kinetic data, and Langmuir, Freundlich and Dubinin-Radushkevich models were correlated to isotherms. Adsorption mechanisms were elucidated for surface features and surface chemistry. The latter was unraveled to have a crucial role on losartan removal by Spectrogel. The best adsorbent dosage was stablished as 6 g/L and initial solution pH (2.5–10) had no significant impact on the process. Spectrogel exhibited faster kinetics and superior maximum adsorption capacity (∼2200 min, 0.0820 mmol/g) than μGAC (∼2600 min, 0.0441 mmol/g). Compared to water or ethanol eluents, methanol showed the highest efficiency as desorption agent (65%). The results indicate that Spectrogel organoclay is a potential non-traditional adsorbent for losartan remediation.