Green composites based on magnetic N-doped carbons: Synergetic effect on the simultaneous adsorption of emerging contaminants from water

This work deals with the removal of emerging contaminants from water by green composites based on mesoporous carbons obtained from glucosamine or a mixture of sucrose and cyanamide, green iron nanoparticles prepared from water hyacinth waste from sewage treatment plants, and proanthocyanidins as natural crosslinking agent. The composites were characterized and applied in dye adsorption of malachite green (MG), crystal violet (CV), methyl orange, and safranin, and the pharmaceutical drugs atenolol (ATN) and sodium diclofenac (SD). The removal of MG and CV was studied in detail, and the maximum adsorption capacity was 713.26 and 606.79 mg center dot g- 1, respectively. The experimental data best fit to the pseudo-second-order kinetic model for both dyes. The material exhibited an excellent synergistic effect in the uptake of ATN and SD in the presence of MG, increasing the adsorption rate by in 57 % and 404 %, respectively, compared to the pharmaceutical drugs treated individually. The composite removed 91 and 98 % of MG and CV dyes from a river water sample, even in the presence of interferences (salts and organic matter). Also, the composite could be applied in 7 cycles of reuse, up to 70 % of recycling efficiency. The electrostatic and pi - pi interactions and hydrogen bonding were identified as the mechanisms of adsorption.