▎ 摘　　要

Application of diverse adsorbents (graphene, nano-Fe3O4, nano-clay and organically modified nanoclay [ONC]) in adsorbing nitrate from aqueous solution has been studied. Four adsorption isotherm models (Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich) were applied to fit the adsorption data at equilibrium and the optimal isotherm of each adsorbent was found. Furthermore, three kinetic models (pseudo-first-order, pseudo-second-order, and intra-particle diffusion) were performed to fit the adsorption data for all of the above-mentioned adsorbents. The highest adsorbent capacity (q(m)) enhances from 44.64 to 243.90 mg g(-1) with changing adsorbent from graphene to modified nanoclay. The sequence corresponding to q(m) obtained to be as the subsequent by altering the adsorbents: graphene < nano-Fe3O4< nano-clay < ONC. Comparison of the correlation coefficients corresponding to adsorption isotherms shows that fitting graphene is better than the Dubinin-Radushkevich model, however, three other adsorption procedures fit with the Langmuir model. The adsorption kinetics is studied through fitting the observed time profiles into the pseudo-first-order (PFO), pseudo-second-order, and intra-particle diffusion (IPD) kinetic models. Adsorbing nitrate by graphene, coordinates well with the pseudo-second-order model and also with IPD model with two separated straight lines representing that two phases affect the sorption procedure. Nano-Fe3O4 adsorption procedure follows both first-order and second-order models. The IPD model is completely in agreement with the adsorption by nano-clay with a straight line, representing that the sorption procedure is controlled with intra-particle diffusion. Both pseudo-second-order model and IPD model can be utilized for describing the sorption kinetics by ONC. Based on the PFO model and comparison of kinetic constant (k(1)), the order of adsorption speed was graphene < nano-Fe3O4 < nano-clay < ONC.