محبوبه شیرانی

This study aimed to use functionalized peach stone as an agricultural waste and use it as a novel selective green sorbent for removal of nitrate ions. The modification process included the function alization of peach stone powder with amine groups using triethylamine. The synthesized sorbent was characterized with a Fourier transform infrared spec trometer, scanning electron microscopy, energy dis persive spectroscopy, and Brunauer–Emmett–Teller techniques to confirm the amine groups immobiliza tion on the surface of the biosorbent. The sorption of nitrate ions on the unmodified peach stone and amine functionalized peach stone was explored as a function of pH, temperature, contact time, initial nitrate con centration, and amount of sorbent in a batch sorption process. The obtained results indicated that sorption of nitrate ions under the optimum conditions was strikingly improved onto Amine@PS compared to PS in which the nitrate removal (%) of 100 and 72.5 were obtained for the Amine@PS after passing 5 min at ambient temperature and for PS after passing 20 min. These results highlight the role of amine functional groups in efficiently increasing the adsorption of nitrate ions and removal (%). Kinetic studies revealed that the adsorption process attained equilibrium after an extra short time of 5 min and followed the pseudo second-order rate equation. The isothermal data fitted better with the Langmuir model than the Freundlich model. Moreover, the maximum adsorption capacity of 476.19 mg g−1 was achieved via Langmuir model at optimum conditions. The obtained thermodynamic parameters (ΔHº, ΔSº and ΔGº) clarified that adsorp tion of nitrate onto Amine@PS was spontaneous and exothermic. Application of Amine@PS for treatment of various water samples including industrial efflu ents containing nitrate ions showed significant poten tial of the proposed method.