Characterization and Mechanism Elucidation of Dye Adsorption Using Cuprous Selenide Nanoparticles from Aqueous Solutions

The removal of cationic dyes, methylene blue(MB) and rhodamine B(RB), and anionic dyes, methyl orange(MO) and eosin Y(EY), from aqueous solutions by adsorption using Cu2Se nanoparticles(Cu(2)SeNPs) was studied. The effects of the initial pH values, adsorbent doses, contact time, initial dye concentrations, salt concentrations, and operation temperatures on the adsorption capacities were investigated. The adsorption process was better fitted the Langmuir equation and pseudo-second-order kinetic model, and was spontaneous and endothermic as well. The adsorption mechanism was probably based on the electrostatic interactions and pi-pi interactions between Cu(2)SeNPs and dyes. For an adsorbent of 0.4 g/L of Cu(2)SeNPs, the adsorption capacities of 23.1(MB), 22.9(RB) and 23.9(EY) mg/g were achieved, respectively, with an initial dye concentration of 10 mg/g(pH=8 for MB and pH=4 for RB and EY) and a contact time of 120 min. The removal rate of MB was still 70.4% for Cu(2)SeNPs being reused in the 5th cycle. Furthermore, the recycled Cu(2)SeNPs produced from selenium nanoparticles adsorbing copper were also an effective adsorbent for the removal of dyes. Cu(2)SeNPs showed great potential as a new adsorbent for dyes removal due to its good stability, functionalization and reusability.