Introduction of nitrogen doped graphene nanosheets as efficient adsorbents for nitrate removal from aqueous samples

Introducing and developing new kinds of adsorbents are always a significant challenge in water treatments. In this work, for the first time, graphene oxide (GO), nitrogen-doped graphene oxide (ND-GO), highly nitrogen-doped graphene oxide (HND-GO), and ۳D high nitrogen-doped graphene oxide (۳D-HND-GO) were synthesized and comparatively evaluated in the removal of nitrate content of tap and underground waters. Based on the results, ۳D-HND-GO showed the highest removal efficiency in comparison with the other mentioned nanoparticles. In addition, the optimal removal condition was achieved using the Nelder-Mead non-linear optimization algorithm as follow: the initial concentrations of nitrate (expressed as nitrogen): ۱۵.۰ mg/mL, the amount of the adsorbent: ۲.۰ mg/mL; pH of the sample: ۳.۰; and the contact time: ۲۰.۰ min. Under this optimal condition, the actual removal result (۹۲.۵ ± ۴.۰%) was in good agreement with the expected value (۹۴.۸ ± ۵.۱%). The adsorption isotherm complied with the Langmuir model illustrating the considerable mono-layer adsorption capacities for the target ions with qm of ۸.۷ mg/g. This study revealed which ۳D-HND-G leads to improved yield in the nitrate ions elimination, particularly at acidic media, which was related to the enhanced dispersibility and larger surface area. The adsorbent was further successfully used for treating tap and underground water samples. At the present moment, research as grown to modify ۳D-HND-G in orders to increase the potentiality for industrial applications.