The ammonium persulfate-initiated copolymerization of sodium humate with functional components: Obtaining superabsorbent microgels decorated with high-energy-density ammonium nitranilate nanoparticles

This study introduces an innovative method for synthesizing multifunctional water-retaining agents via ammonium persulfate-initiated alkaline copolymerization of sodium humate with diverse functional components. The resulting materials exhibit exceptional and reproducible water/saline absorbing capabilities, outstanding water retention performance, and remarkable UV resistance. Structural characterization demonstrates that sodium humate's graphite backbone can be either preserved or modified depending on the copolymerized components, with polyvinyl alcohol (37.41–93.82 g g⁻¹) and polyvinyl pyrrolidone (39.23–97.66 g g⁻¹) composites showing particularly superior water absorption properties over 18 recycling cycles. A significant discovery is the concurrent formation of ammonium nitranilate, a high-energy-density salt, whose production from humic acid not only confirms Stevenson's structural model featuring quinone moieties but also offers an economical alternative to conventional chloranil-based synthesis that requires hazardous chlorine gas and expensive precursors. This work thus accomplishes dual breakthroughs: developing high-performance irrigation materials for arid regions while establishing a highly effective valorization pathway for humic acid to produce valuable energetic compounds.