Sorption Capacity of Carbon-Based Mandarin Orange Peels for Removing Methylene Blue and Ibuprofen from Water

Abstract

Pharmaceutical pollutants in water pose a serious environmental challenge. This research compared the adsorption capacity of mandarin orange peels (MOP) and activated carbon mandarin orange peels (AC-MOP) to adsorb methylene blue (MB) and Ibuprofen (IBF) from an aqueous solution. This is the first study to report on the uptake of Ibuprofen using carbonized mandarin orange peels activated with hydrochloric acid. The biomaterials were characterized using FTIR and SEM. Batch experiments with operational parameters such as pH, contact time, concentration and temperature were investigated for the adsorption of MB and IBF. Isotherms, kinetic calculations and thermodynamic parameters were calculated for the adsorption of MB and IBF. A positive ΔH° suggested the reaction was endothermic, and ΔG° values showed that the sorption process was spontaneous. The isotherm models best fit the Langmuir model with maximum sorption capacities of 74.15 and 78.15 mg/g for MB and IBF, respectively. The adsorption rate for MB was fast and took place within the first 10 min, whilst the removal of IBF was observed at 40 min. The kinetic model evaluation showed that pseudo-second-order was a suitable fit for the mechanism. The re-usability data indicated that the recovery of MB was 70.13%, and IBF was 87.17%. The adsorption capacity of IBF with the carbon-based MOP was higher than that of MB. The results indicated that AC-MOP could be used as an adsorbent for MB and IBF from water. The major advantage of this method is its effectiveness in reducing the concentration of dyes and pharmaceutical pollutants using inexpensive adsorbents.