Waste Feather Keratin Composited Geopolymer Hydrogels for Improving Plant Water Retention and N Nutrients Utilization

To improve cyclic utilization of waste feather resources and enhance the efficiency of crop fertilizer, a novel superabsorbent slow-release hydrogels were prepared by feather keratin (FK), diatomite geopolymer (DG), urea and acrylic acid (AA) with thiol-ene click reaction and in-situ polymerization, which afforded FK composited DG polymer hydrogels containing urea (Urea@FK/DG-HGs). After characterizing structure and microscopic morphology, its swelling capacity, water retention and slow-release behavior were investigated. The obtained Urea@FK/DG-HGs presented good swelling, cyclic stability, foliar adhesion, water retention and slow-release properties. The swelling ratios got to 666.67 g/g in distilled water and 107.53 g/g in the saline solution (0.9% NaCl), respectively. The swelling rate was still 209.9 g/g after recycling 8 times. It enhanced the water retention performance of the soil and prolonged nutrients release, which the cumulative release of urea was 34.8% after 45 days, and the release behavior was belong to Fickian diffusion. Furthermore, the obtained Urea@FK/DG-HGs was used in agricultural applications to improve plant growth and proved to have a promotional effect on the germination and growth of holly seeds. In summary, it was an effective strategy for reutilization of agricultural waste by adding waste feathers keratin into slow-release hydrogel. And the obtained