Evaluation of the efficiency of P4VP-Fe3O4 nanocomposite on the removal of diclofenac from aqueous solutions

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been widely used in various treatments including inflammatory disorders, pain relief and fever. The permanent presence of these compounds in water resources and possible adverse effects due to toxicological and chemical properties is very important. The aim of this study was to evaluate of the efficiency of P4VP-Fe3O4 nanocomposite on the removal of diclofenac from aqueous solutions.

Adsorbent properties were determined by TEM, SEM, VSM and FTIR techniques. Effect of independent variables such as pH (3-9), adsorbent dose (0.1-2 g/L), contaminant concentration (2-20 mg/L), mixing speed (100-250 rpm), temperature (25-40°C) and the presence of interfering ions (120 min) were investigated. The adsorption process was evaluated using Langmuir, Freundlich, Tamkin isotherm models, and kinetic models of the adsorption process as well as thermodynamic studies.

Results showed that by examining the size and shape of P4VP-Fe3O4 composite, the composite had properties such as nano range size, polygonal structure and non-uniform shape. The peak of the pyridine ring in the results of FT-IR analysis of P4VP@Fe3O4 composite indicated the presence of C=C bands. In the adsorption process, the optimal removal conditions for diclofenac (contaminant concentration 15 mg/L, pH=5, contact time 75 min, adsorbent dose 1 g/L), the maximum removal efficiency of diclofenac 93.34% and adsorption capacity (qe) 9.33 mg/g was obtained. Also, the study of adsorption isotherm and kinetics showed that diclofenac adsorption followed Freundlich isotherm (R2 <0.956) and quasi-quadratic kinetic model (R2 <0.976). The results of thermodynamics also showed a spontaneous reaction.

P4VP-Fe3O4 composite can be used as an effective and useful adsorbent in the adsorption of diclofenac and pharmaceutical compounds from aqueous media due to its advantages such as simple and fast separation, recyclable, cost-effective and high removal efficiency.