Biosorption of ketoprofen and diclofenac by living cells of the green microalgae Chlorella sp.

There is a growing interest for the removal of different pharmaceuticals from water owing to their toxicity to various organisms. The present study investigated the use of living cells of the green alga Chlorella sp. in the short-term adsorption of ketoprofen (KET) and diclofenac (DIF) from aqueous solutions. The bioremoval efficiency of both KET and DIF was highly dependent on various parameters such as time, pH, algal dosage, and drug concentration. The adsorption efficiencies of both KET and DIC were maximized at pH 6. The biosorption of KET was better described by pseudo-first-order kinetics, while DIC obeyed the pseudo-second-order model. The maximum adsorption capacities of KET and DIF were attained as 0.328 and 0.429 mg g, respectively. The equilibrium data of the investigated drugs showed a better fit to the Freundlich model than the Langmuir model. The Elovich and Temkin models indicated that the algal surface was heterogeneous with different binding energies, while the intraparticle diffusion model assumed a boundary layer effect. Additionally, the Dubinin-Radushkevich isotherm indicated that the adsorption process was predominantly physisorption. FT-IR analysis revealed that H-bonding and n-π interactions were prominent in the biosorption process of the investigated pharmaceuticals on the surface of microalgae. The results of the present study showed that microalgae living cells could be applied as an eco-friendly and cost-effective biosorbent for the removal of KET and DIF at low concentrations.