Adsorption of Ammonium by Graphene Oxide-Based Composites Prepared by UV Irradiation and Using as Slow-Release Fertilizer

摘要

A novel sodium alginate-grafted poly(acrylic acid)/graphene oxide (NaAlg-g-PAA/GO) composite hydrogel was prepared via ultraviolet irradiation, and characterized by infrared spectroscopy spectrometer. X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. It was employed to adsorb NH4+ from aqueous solution and used as slow-release nitrogen fertilizers (SNFs). Result indicated that the adsorption process for NH4+ reached equilibrium within 50min, with the adsorption capacity of 6.6mmolg(-1) even if 30wt% GO was incorporated. The results of adsorption kinetic and isotherm were well described by the pseudo-second-order and Freundlich model. The thermodynamics analysis showed the adsorption process was spontaneous. The study indicated excellent water-holding ratio of soil with 2wt% SNFs was 81.2%, and nitrogen release was up to 55.1% within 40days in soil. Overall, NaAlg-g-PAA/GO could be considered as an efficient adsorbent for the recovery of nitrogen with the agronomic reuse as a fertilizer.