In this study, a novel slow release carrier for the controlled release of citric acid (CA), hydroxypropyl chitosan-graft-carboxymethyl-β-cyclodextrin (HPCS-g-CMCD) was synthesized by the grafting reaction of carboxymethyl-β-cyclodextrin (CMCD) with hydroxypropyl chitosan (HPCS), and the structural characteristics of HPCS-g-CMCD were confirmed by FT-IR, TGA, and NMR. Based on HPCS-g-CMCD and CA, slow release citric acid (SRCA) was prepared by a spray drying method. HPCS-g-CMCD carrier has a better slow release performance for CA compared to HPCS and CMCD, and CA release mechanism was attributed to a Fickian diffusion. Furthermore, the release behavior of uranium in contaminated soil could be effectively controlled by SRCA. The effects of SRCA on improving the phytoremediation capacity in uranium-contaminated soil were investigated using Brassica juncea, which were grown in pots containing soil with uranium at 56 mg kg⁻¹. After 50 days of growth, 5 mmol kg⁻¹ of CA, SRCA I, SRCA II, and SRCA III was applied, respectively. The results showed that slow release citric acid could enhance the uptake of uranium in Indian mustard. Uranium concentration in the root with SRCA I treatment was increased by 80.25% compared to the control, and the uranium removal efficiency of the SRCA I treatment was 1.66-fold greater than that of the control. Simultaneously, the leaching loss of uranium in SRCA I-treated soil was decreased by 37.35% compared to CA-treated soil. As a promising remediation strategy, SRCA-assisted phytoremediation may provide a kind of feasible technology with low leaching risk for remediation of uranium-contaminated soils.

本研究通过羧甲基-β-环糊精的接枝反应合成了一种新型的柠檬酸（CA）缓释载体羟丙基壳聚糖-接枝-羧甲基-β-环糊精（HPCS-g-CMCD）（ CMCD) 与羟丙基壳聚糖 (HPCS), 并通过 FT-IR、TGA 和 NMR 证实了 HPCS-g-CMCD 的结构特征。基于HPCS- g -CMCD和CA，采用喷雾干燥法制备缓释柠檬酸（SRCA）。HPCS- g-与HPCS和CMCD相比，CMCD载体对CA具有更好的缓释性能，CA释放机制归因于Fickian扩散。此外，SRCA可以有效控制铀在污染土壤中的释放行为。使用芥菜研究了 SRCA 对提高铀污染土壤植物修复能力的影响，芥菜生长在含有 56 mg kg ^-1铀的土壤中。生长 50 天后，5 mmol kg ⁻¹分别应用 CA、SRCA I、SRCA II 和 SRCA III。结果表明，缓释柠檬酸可以提高印度芥末中铀的吸收。与对照相比，SRCA I处理的根部铀浓度增加了80.25%，SRCA I处理的铀去除效率是对照的1.66倍。同时，与 CA 处理的土壤相比，SRCA I 处理的土壤中铀的浸出损失减少了 37.35%。作为一种有前途的修复策略，SRCA 辅助植物修复可能为铀污染土壤的修复提供一种具有低浸出风险的可行技术。