Tiamwong Supattra, Yukhajon Pratchayaporn, Noisong Pittayagorn, Subsadsana Maliwan, Sansuk Sira
Materials Chemistry Research Center, Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand.
Program of Chemistry, Faculty of Science and Technology, Nakhon Ratchasima Rajabhat University, Nakhon Ratchasima 30000, Thailand.
Gels. 2023 Mar 7;9(3):204. doi: 10.3390/gels9030204.
Environmentally friendly fertilizers (EFFs) have been developed to improve fertilizer efficiency and minimize adverse environmental impacts, but their release behavior under various environmental conditions has been less explored. Using phosphorus (P) in the form of phosphate as a model nutrient, we present a simple method for preparing EFFs based on incorporating the nutrient into polysaccharide supramolecular hydrogels using starch in the Ca-induced cross-link gelation of alginate. The optimal conditions for creating these starch-regulated phosphate hydrogel beads (s-PHBs) were determined, and their release characteristics were initially evaluated in deionized water and then under various environmental stimuli, including pH, temperature, ionic strength, and water hardness. We found that incorporating a starch composite in s-PHBs at pH = 5 resulted in a rough but rigid surface and improved their physical and thermal stability, compared with phosphate hydrogel beads without starch (PHBs), due to the dense hydrogen bonding-supramolecular networks. Additionally, the s-PHBs showed controlled phosphate-release kinetics, following a parabolic diffusion with reduced initial burst effects. Importantly, the developed s-PHBs exhibited a promising low responsiveness to environmental stimuli for phosphate release even under extreme conditions and when tested in rice field water samples, suggesting their potential as a universally effective option for large-scale agricultural activities and potential value for commercial production.
环保肥料（EFFs）已被开发出来以提高肥料效率并将不利的环境影响降至最低，但它们在各种环境条件下的释放行为仍未得到充分研究。以磷酸盐形式的磷（P）作为模型养分，我们提出了一种制备环保肥料的简单方法，即利用淀粉在藻酸盐的钙诱导交联凝胶化过程中将养分掺入多糖超分子水凝胶中。确定了制备这些淀粉调节的磷酸盐水凝胶珠（s-PHBs）的最佳条件，并首先在去离子水中，然后在包括pH值、温度、离子强度和水硬度在内的各种环境刺激下评估了它们的释放特性。我们发现，在pH = 5的条件下，在s-PHBs中加入淀粉复合材料会使其表面粗糙但坚硬，并提高其物理和热稳定性，与不含淀粉的磷酸盐水凝胶珠（PHBs）相比，这是由于密集的氢键超分子网络所致。此外，s-PHBs显示出可控的磷酸盐释放动力学，遵循抛物线扩散且初始突释效应降低。重要的是，所开发的s-PHBs即使在极端条件下以及在稻田水样中测试时，对环境刺激下的磷酸盐释放也表现出有前景的低响应性，表明它们作为大规模农业活动的普遍有效选择的潜力以及商业生产的潜在价值。
