Utilization of Moringa oleifera seeds as a biosorbent for diclofenac removal in the contaminated aquatic systems

Abstract

During recent years, pharmaceuticals and their metabolites have been increasingly found in water bodies and diclofenac is one of the pharmaceuticals residues most frequently detected thus far. The aim of this work was to evaluate the Moringa oleifera seeds as an alternative for diclofenac (DCF) removal in water samples. The batch procedure for DCF removal at the optimized conditions (25 mL of 10.0 mg L−1 DCF, pH 5.0, extraction time of 30 min and M. oleifera mass of 2.0 grams) achieved adsorption of 100% of DCF in real water samples. The pseudo-second-order kinetic described the adsorption rate-controlling step. The adsorption isotherms were fitted by Langmuir, Freundlich and Sips models and the sorption capacity of the biosorbent is spontaneously favourable. The maximum adsorptive capacity was estimated at 32.05 mg g−1 and 32.85 mg g−1 by Langmuir and Sips models, respectively. The advantages of this procedure include good reproducibility in the removal of DCF even at low concentrations in real samples and does not require an additional step of pre-treatment of the adsorbent. The results highlight the potential of M. oleifera seeds as a cheap, environmentally friendly alternative for the removal of DCF from polluted water. HIGHLIGHTS Moringa oleifera seeds were efficient in the adsorption of diclofenac obtaining removals greater than 95%.; The adsorptive capacity of moringa was sufficient for remediation of contaminated water without any structural change of the adsorbent.; The adsorption rate is determined by the chemical interactions.; Adsorption equilibrium is reached spontaneously.; The procedure was satisfactorily applied to real environmental samples.;

Keywords

• biosorbent
• diclofenac
• emerging contaminants
• moringa oleifera
• remediation
• water