Investigation of behaviours of diclofenac adsorption onto different adsorbents of carbon- aerogel by the kinetic and isotherm non-linear models

Abstract

ABSTRACT The application of eco-friendly, economically justifiable and reusable materials in removing pollutants from the aqueous solutions has received much attention. Therefore, in the present study, three adsorbents (carbon/aerogel (CA), carbon/aerogel/nickel (CAN) and carbon/aerogel/magnetite (CAM)) were used to remove diclofenac from the aqueous solutions. The various techniques such as brunauer-emmett-teller (BET), thermogravimetric (TGA), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to investigate the structure and main composition of the target adsorbents. The average size and specific surface area for CA, CAN and CAM adsorbents were obtained (6.5 nm and 714.93 m2 g−1), (1.61 nm and 734.32 m2 g−1) and (1.65 nm and 1193.9 m2 g−1), respectively. The maximum amount of the adsorbed pollutant on CA, CAN and CAM adsorbents were determined to be 60 mg g−1 (based on Sips), 101.9 mg g−1 (based on Langmuir) and 78 mg g−1 (based on Khan), respectively. The experimental data obtained for CA, CAN and CAM showed the best fit with Sips, Langmuir and Khan isotherms, respectively. In addition, the best kinetic models to express the adsorption characteristics of CA, CAN and CAM adsorbents were pseudo-first order, pseudo-first order and pseudo-second order, respectively. The performances of the CAN and CAM adsorbents were investigated for six consecutive cycles. The efficiency of CA, CAN and CAM adsorbents in diclofenac adsorption in the first and sixth cycles were (84% and 55%), (90% and 67%) and (88% and 63%), respectively.