Dense and superhydrophobic biopolymer-coated large tablet produced with energy efficient UV-curing for controlled-release fertilizer

Large tablet controlled-release fertilizers (LCRFs) can significantly improve nutrient utilization and reduce coating costs. However, traditional petrochemical coating materials are expensive and non-renewable. Furthermore, conventional heat-curing coating process is both time and energy consuming and severely impairs the controlled-release characteristics of LCRFs. To solve above problems, green processes using renewable biomaterials have become the research hotspot for the new generation of LCRFs. In this work, bio-based polyurethane acrylate (BPUA), synthesized from castor oil, was used to coat large tablet by an innovative UV-curing process for controlled-release fertilizer to overcome the drawbacks of the heat-curing process. Furthermore, BPUA was modified with polydimethylsiloxane (PDMS) and thiol grafted nanosilica (TNS) to prepare dense and superhydrophobic biopolymer-coated large tablet controlled-release fertilizer (DSBCF). The DSBCF exhibited remarkable controlled-release characteristics with a nitrogen release longevity of nearly 120 days, requiring only 4% of the coating materials. This research provides an efficient UV-curing strategy to manufacture energy saving, superior performance and biopolymer-coated LCRFs. It can solve bottlenecks that limit the development of coated fertilizers and provide theoretical and technical support for the green upgrade of the industry. This work provides an efficient UV-curing strategy for the manufacture of energy-saving, superior performance and biopolymer-coated large tablet controlled-release fertilizers.