▎ 摘　　要

The removal efficiency of two anionic dyes, namely direct red 81 (DR 81) and reactive blue 19 (RB 19), from aqueous solution was investigated through batch adsorption experiments by using magnetic graphene oxide coated with branched-polyethylenimine (PEI/MGO) nanocomposite as an adsorbent. The physicochemical properties of PEI/MGO were analyzed via FTIR, XRD, FE-SEM, EDS, VSM, TGA, and BET methods. The removal efficiency of dyes was evaluated as a function of various parameters (initial solution pH, adsorbent dosage, contact time, temperature, initial dye concentration, and ionic strength). The nonlinear form of fractal-like pseudo-second-order kinetic and Freundlich isotherm models described reasonably the adsorption mechanism. The maximum adsorption capacity of PEI/MGO for DR 81 and RB 19 at pH 3.0 and 328 K was calculated to be 284.3 and 269 mg g(-1), in the respective order that was much higher than that of MGO. The thermodynamic analysis revealed that the adsorption is a physisorption process with a spontaneous and endothermic characteristic. In addition, regeneration experiments demonstrated that the recyclability of PEI/MGO is encouraging. Finally, data from the preliminary application of 30 mg of PEI/MGO to remove DR 81 and RB 19 (40 mg L-1) from 40 mL of spiked groundwater samples indicated greater than 99% and 95% recovery, respectively, with the contact time of 30 min at room temperature. According to the experimental results, the PEI/MGO is potentially capable of purifying anionic dyes-polluted water.