【摘要】 随着农业的快速发展，土壤退化已成为全球性的重大问题。制备一种具有缓释功能的新型土壤改良剂对于改善土壤理化性质，保障农业可持续发展具有重要意义。以海藻酸钠/木炭的复合材料为载体，采用一体化滴注法制备了装载腐殖酸的缓释凝胶球。探究了凝胶球的微观形貌和载药量，在不同pH条件下对凝胶球进行了缓释实验，并采用零级、一级、Higuchi和Ritger-Peppas模型拟合腐殖酸的释放曲线。结果表明：海藻酸钠/木炭凝胶球具有良好的缓释性能和明显的pH响应性，当pH从4.0增加到10.0,腐殖酸的累计释放量从31.89%增加到92.19%,且海藻酸钠/木炭凝胶球在20 h的释放速率相比于单一海藻酸钠凝胶球有19.71%～40.95%的下降，释放过程也更为复杂。根据缓释动力学模型拟合，腐殖酸在不同pH条件下的释放规律符合Fick扩散。综上所述，海藻酸钠/木炭凝胶球具有良好的稳定性、缓释性和pH响应性。本研究为增强土壤改良剂的利用效率并延长其使用时间提供了一种绿色、低成本且制备简便的新型缓释材料，与传统的改良剂相比具有更加广阔的应用前景。更多还原

【Abstract】 In recent years, with the rapid development of agriculture, soil degradation has become a global problem, seriously threatening the sustainability of land use worldwide. A new soil conditioner with a slow-release function is important to improve the physical and chemical properties of soil and ensure the sustainable development of agriculture. In this paper, slow-release gel spheres loaded with humic acid were prepared by an integrated drip injection method using a composite of sodium alginate/charcoal as a carrier. The scanning electron microscope（SEM） and Fourier transform infrared spectrometer（FT-IR） were used to characterize the microstructure, morphology, and interactions of the retarded materials, and the slow-release experiments were carried out on the gel spheres under different pH conditions, and the release curves of humic acid were fitted using zero-order, first-order, Higuchi models and Ritger-Peppas model. The experimental results showed that the introduction of charcoal into sodium alginate gel spheres can increase the humic acid loading from 54.89% to 62.31%. Charcoal particles were uniformly dispersed on the surface and in the three-dimensional network structure of the sodium alginate/charcoal gel spheres, and the oxygen-containing functional groups in the charcoal reacted with the polymer chains through hydrogen bonding to provide co-crosslinking sites for Ca²⁺, which improved the mechanical strength and stability of the sodium alginate/charcoal gel spheres, and also provided loading sites for the humic acid, improving the slow-release performance of the gel spheres. Compared with the gel spheres without charcoal, the release times of sodium alginate/charcoal gel spheres in buffer solutions with pH of 4.0-10.0 were all significantly increased without sudden release. Meanwhile, the sodium alginate/charcoal gel spheres were significantly pH-responsive, and the cumulative release of humic acid increased from 31.89% to 92.19% when the pH value was increased from 4.0 to 10.0. The release rates of sodium alginate/charcoal gel spheres at different pH values were significantly reduced compared to individual sodium alginate gel spheres. According to the slow-release kinetic model fitting, the release pattern of humic acid under different pH conditions was consistent with the Fick diffusion, and the release process was more complex. In conclusion, the sodium alginate/ch arcoal gel spheres had good stability, slow release, and pH responsiveness, which effectively addressed the problems of instability, “sudden release” and low drug loading capacity of single sodium alginate gel spheres. This study provides a new green, low-cost, easy-preparation, and slow-release material to enhance the utilization efficiency and extend the use time of the improver, which has a broader application prospect compared with the traditional improvers.更多还原