众多放射性核素中，被称为“核业基石、核电粮仓”的铀资源，位列能源矿产和战略资源之首，成为我国推动核电事业发展、优化能源供给结构的源动力。在其一系列开发应用过程中，排放于周边环境中的含铀废渣和废液对人体健康和生态环境构成了极大威胁。吸附技术是目前处理净化含铀废水的有效举措，多糖物质壳聚糖因其廉价易得、可生物降解、活性基团多样等特性而备受关注。本文旨在以壳聚糖（CS）为基底材料，选用无机磷酸盐三聚磷酸钾（KTPP）和有机膦酸二乙烯三胺五甲叉膦酸（DTPMP）作为无机/有机磷源，研发多种含磷壳聚糖衍生物复合吸附剂用于含铀废水中铀的吸附提取，通过静态批次试验考察了其在不同条件下的除铀性能、探究了铀酰去除机制。研究取得的主要成果如下：

（1）以KTPP作为阴离子交联剂，于室温条件下合成了KTPP交联盐酸质子化壳聚糖（CTPP）复合吸附剂。响应面法分析结果表明，制备过程中壳聚糖质子化溶解程度与体系酸化程度呈正相关，体系pH为6.0时随着质子化反应时间延长去质子化现象逐渐突显，体系pH为2.0时壳聚糖质子化溶解所需反应时间可适当延长。扫描电镜图像显示材料呈现不同交织程度的纤维网状结构，增大制备体系酸化程度有助于改善交联密度。相同条件下测得除铀效果最佳材料CTPP-2对应的制备条件如下：体系pH为2.0、质子化时间为30 min、交联时间为5 h。由批次吸附试验结果可知，在溶液初始pH为5.0、吸附剂投加量为0.4 g/L条件下CTPP-2的铀酰吸附容量是CS的2.4倍，初始阶段15 min内二者基本完成了各自平衡吸附容量的70%和42%，且适当升高反应温度可提升复合材料的铀酰去除率。

（2）以苯甲醛作为氨基保护剂、氯乙酸作为酸化剂、KTPP作为阴离子交联剂，于升温回流条件下合成了KTPP交联氯乙酸强化质子化壳聚糖（MCTPP）复合吸附剂。材料制备阶段L₁₆(4⁵)正交试验分析结果显示，氯乙酸用量和酸化时间对复合材料形貌结构及吸附性能影响较为显著，酸化温度过高会诱导酸性物质加速水解，进而破坏壳聚糖分子链结构、削弱复合材料吸附性能。相同条件下测得除铀效果最佳材料MCTPP-3对应的制备条件如下：壳聚糖/苯甲醛/氯乙酸比值为1:4:4，席夫碱化温度和时长为45℃和2 h，质子化温度和时长为60℃和2 h。由表征图谱可知，磷氧基团的引入极大降低了CS分子间/内的氢键作用，与CS和CTPP相比，MCTPP-3呈现出较强的颗粒感且内部网状镂空形貌显著，比表面积由CS 的1.72增至123.55 m²/g。静态批试验结果表明，溶液初始pH和吸附剂投加量对铀酰去除效果具有强烈影响，在溶液初始pH为5.0、吸附剂投加量为0.4 g/L条件下MCTPP-3的铀酰吸附容量是CS的2.7倍，反应初期10 min内分别达到各自平衡吸附量的84%和40%，吸附过程属于自发吸热反应。

（3）以KTPP作为阴离子交联剂，于室温条件下合成了KTPP交联五元有机膦酸质子化壳聚糖（DTPP）复合吸附剂。由响应面分析结果可知，材料制备过程中增大DTPMP用量对铀酰吸附性能具有促进作用，而增大KTPP用量表现出明显的消极影响。电镜测试结果显示，复合材料的网状交联结构与DTPMP用量呈正相关，同时加大KTPP用量显著增加了材料结构的空间感。相同条件下测得除铀效果最佳材料DTPP-25对应的制备条件如下：DTPMP用量为1.25 mL、质子化时间为5 h、KTPP用量为0.25 g、交联时间为5 h。吸附环节中复合材料除铀性能对溶液初始pH响应程度降低，膦酸基团的成功引入极大改善了酸碱环境中的铀酰吸附量，DTPP-25在pH为2.0和10.0时的饱和吸附量分别为497.38和557.50 mg/g，是改性前CS的12.5和26.5倍，且在15 min内即可实现平衡吸附容量的82%，铀酰吸附效率得到显著提升。

（4）以苯甲醛作为氨基保护剂、五元有机膦酸作为酸化剂、KTPP作为阴离子交联剂，于升温回流条件下合成了KTPP交联有机膦酸强化质子化壳聚糖（DCTPP）复合吸附剂。材料制备环节中L₉(3⁴)正交试验结果表明，DTPMP用量对材料除铀性能具有积极影响，低KTPP用量情形下所得复合材料对铀酰的去除效果优于高交联剂量。相同条件下测得除铀效果最佳材料DCTPP-16 mL对应的制备条件如下：DTPMP用量为16 mL，膦酸化温度为65℃，膦酸化时长为1 h，KTPP用量为1.2 g。批次吸附试验结果显示，当溶液初始pH为5.0、吸附剂投加量为0.4 g/L时，DCTPP-16吸附剂的饱和吸附容量是CS的~3倍，吸附过程仅进行5 min时便可完成平衡吸附容量的90%（CS ≈ 30%），由于其优异的吸附速率和去除效果，提升反应温度对除铀性能稍有改善但整体影响并不显著。

（5）基于多种吸附模型，对已研制的CTPP、MCTPP、DTPP和DCTPP类含磷壳聚糖复合吸附剂进行动力学和等温线分析，拟合结果表明：0-720 min测试区间内，上述复合材料对铀酰离子的吸附过程均遵循准二级和耶洛维奇动力学方程，且颗粒内扩散模型拟合结果表现出三个线性部分，DCTPP-16表现出更高的瞬时扩散速率。CTPP-2和DTPP-25吸附剂在初始铀浓度20-500 mg/L、吸附剂投加量0.2 g/L、25℃条件下，测得Langmuir最大铀酰吸附容量分别为780.89、900.14 mg/g，MCTPP-3和DCTPP-16吸附剂在20-500 mg/L、0.2 g/L、25℃条件下的Langmuir最大吸附容量分别为1487.72和1316.82 mg/g。上述模型分析结果说明复合材料对铀酰的吸附过程并非单一因素影响，而是受表面络合/螯合、化学吸附和颗粒内扩散等多重步骤控制。密度泛函理论计算结果预测了壳聚糖分子与有机膦酸分子、有机膦酸分子与铀酰之间的潜在结合方式，验证了磷氧基团对铀酰的强相互作用。再生性能测试结果反映，同常规酸/碱洗脱剂相比，表面活性剂EDTA对两类强化交联材料具有相对较优的铀酰脱附效果，洗脱液浓度以0.03 M为宜；含铀废水模拟试验结果表明复合吸附剂均表现出可观的实际应用潜能。

Among the numerous radioactive isotopes, uranium, known as the "cornerstone of the nuclear industry" and the "grain storehouse of nuclear power", is the top energy mineral and strategic resource, serving as the driving force for China's promotion of nuclear power development and optimization of energy supply structure. However, the discharge of uranium-containing waste residues and waste liquids into the surrounding environment during its development and application poses a great threat to human health and the ecological environment. Adsorption technology is an effective measure for treating and purifying uranium-containing wastewater, and polysaccharide material chitosan has attracted considerable attention due to its characteristics of low cost, easy availability, biodegradability, and diverse active groups. This article aims to develop various phosphorus-containing chitosan derivatives composite adsorbents for the adsorption and extraction of uranium in uranium-containing wastewater, using chitosan (CS) as the base material, and inorganic phosphate potassium tripolyphosphate (KTPP) and organic phosphonic acid diethylene triamine pentamethylene phosphonic acid (DTPMP) as inorganic/organic phosphorus sources. The uranium removal performance of these adsorbents under different conditions was investigated through static batch experiments, and the uranium removal mechanism was explored. The main achievements of the study are as follows:

(1) KTPP crosslinked protonated chitosan hydrochloride (CTPP) composite adsorbent was synthesized at room temperature using KTPP as anionic cross-linking agent. Response surface analysis results showed that the degree of chitosan protonation dissolution during the preparation process was positively correlated with the system acidification degree. As the protonation reaction time increased, deprotonation phenomenon gradually became evident when the system pH was 6.0, while the protonation reaction time required for chitosan protonation dissolution could be appropriately prolonged when the system pH was 2.0. Scanning electron microscopy images showed that the material had a fibrous network structure with varying degrees of intertwining, and increasing the system acidification degree helped to improve the crosslinking density. Under the same conditions, the optimal uranium removal material CTPP-2 was obtained with the following preparation conditions: system pH of 2.0, protonation time of 30 min, and cross-linking time of 5 h. Batch adsorption experiments showed that under the conditions of initial pH of 5.0 and adsorbent dosage of 0.4 g/L, the uranium adsorption capacity of CTPP-2 was 2.4 times that of CS. Within the initial 15 min, both materials had completed approximately 70% and 42% of their respective equilibrium adsorption capacities. Additionally, increasing the reaction temperature appropriately could improve the uranium removal efficiency of thecomposite material.

(2) KTPP crosslinked chloroacetic acid enhanced protonated chitosan (MCTPP) composite adsorbent was synthesized under the condition of temperature reflux using benzaldehyde as amino protective agent, chloroacetic acid as acidifier and KTPP as anion crosslinking agent. L₁₆(4⁵) orthogonal experiment analysis during the material preparation stage showed that the amount of chloroacetic acid used and the acidification time had a significant impact on the morphology, structure, and adsorption performance of the composite material, and excessively high acidification temperature could induce the acceleration of hydrolysis of acidic substances, thereby destroying the chitosan molecular chain structure and weakening the adsorption performance of the composite material. Under the same conditions, the optimal uranium removal material MCTPP-3 was obtained with the following preparation conditions: chitosan/benzaldehyde/chloroacetic acid ratio of 1:4:4, Schiff base alkalization temperature and duration of 45°C and 2 h, and protonation temperature and duration of 60°C and 2 h. According to the characterization spectra, the introduction of phosphonate groups greatly reduced the hydrogen bonding interaction between CS molecules, and compared with CS and CTPP, MCTPP-3 showed a strong particle-like feeling with a significant internal network-shaped hollow structure, and the specific surface area increased from 1.72 m²/g to 123.55 m²/g. Static batch experiments showed that the initial pH of the solution and the adsorbent dosage strongly influenced the uranium removal effect. Under the conditions of initial pH of 5.0 and adsorbent dosage of 0.4 g/L, the uranium adsorption capacity of MCTPP-3 was 2.7 times that of CS, and within the first 10 min of the reaction, they had achieved 84% and 40% of their respective equilibrium adsorption capacities. The adsorption process was a spontaneous endothermic reaction.

(3) Using KTPP as anionic cross-linking agent, KTPP cross-linked five-membered organic phosphonic acid protonated chitosan (DTPP) composite adsorbent was synthesized at room temperature. According to the response surface analysis results, increasing the DTPMP dosage during the material preparation process had a promoting effect on the uranium adsorption performance, while increasing the KTPP dosage showed a significant negative impact. The electron microscopy test results showed that the network crosslinking structure of the composite material was positively correlated with the DTPMP dosage, and increasing the KTPP dosage significantly increased the spatial feeling of the material structure. Under the same conditions, the optimal uranium removal material DTPP-25 was obtained with the following preparation conditions: DTPMP dosage of 1.25 mL, protonation time of 5 h, KTPP dosage of 0.25 g, and cross-linking time of 5 h. During the adsorption process, the uranium removal performance of the composite material was less responsive to the initial pH of the solution, and the successful introduction of the phosphonic acid group greatly improved the uranium adsorption capacity in acidic and alkaline environments. DTPP-25 had a saturated adsorption capacity of 497.38 mg/g and 557.50 mg/g at pH 2.0 and 10.0, respectively, which was 12.5 and 26.5 times that of unmodified CS. Additionally, within 15 minutes, it could achieve 82% of its equilibrium adsorption capacity, and the uranium adsorption efficiency was significantly improved.

(4) KTPP crosslinked organic phosphonic acid enhanced protonated chitosan (DCTPP) composite adsorbent was synthesized under the condition of temperature reflux using benzaldehyde as amino protective agent, pentadic organic phosphonic acid as acidifier and KTPP as anion crosslinking agent. The results of the L₉(3⁴) orthogonal experiment during the material preparation process showed that the DTPMP dosage had a positive impact on the uranium removal performance, and the composite material obtained under low KTPP dosage showed better uranium removal effect than that obtained under high cross-linking agent dosage. Under the same conditions, the optimal uranium removal material DCTPP-16 mL was obtained with the following preparation conditions: DTPMP dosage of 16 mL, phosphonation temperature of 65°C, phosphonation duration of 1 h, and KTPP dosage of 1.2 g. Batch adsorption test results showed that when the initial pH of the solution was 5.0 and the adsorbent dosage was 0.4 g/L, the saturated adsorption capacity of DCTPP-16 adsorbent was approximately 3 times that of CS. The adsorption process was completed within only 5 minutes, achieving 90% of its equilibrium adsorption capacity (CS ≈ 30%). Due to its excellent adsorption rate and removal effect, increasing the reaction temperature slightly improved the uranium removal performance, but the overall effect was not significant.

(5) Based on multiple adsorption models, the composite adsorbents containing phosphorus, namely CTPP, MCTPP, DTPP, and DCTPP were analyzed for their kinetics and isotherms. The fitting results showed that within the 0-720 min test interval, the adsorption process of the above composite materials on uranyl ions followed the pseudo-second-order and elovich kinetics equations. The intraparticle diffusion model showed three linear parts, with DCTPP-16 exhibiting a higher instantaneous diffusion rate. The Langmuir maximum uranyl adsorption capacities of CTPP-2 and DTPP-25 adsorbents were found to be 780.89 and 900.14 mg/g, respectively, under initial uranium concentration of 20-500 mg/L, adsorbent dosage of 0.2 g/L, and 25°C. The Langmuir maximum adsorption capacities of MCTPP-3 and DCTPP-16 adsorbents were 1487.72 and 1316.82 mg/g, respectively, under the same conditions. The above model analysis results showed that the adsorption process of uranyl on the composite material was not solely affected by a single factor, but was controlled by multiple steps including surface complexation/chelation, chemical adsorption, and intraparticle diffusion. Density functional theory calculations predicted the potential binding modes between chitosan molecules and organic phosphonic acid molecules, and between organic phosphonic acid molecules and uranyl ions, verifying the strong interaction of the phosphonate groups with uranyl ions. The regeneration test results showed that compared with conventional acid/base eluents, the surfactant EDTA had a relatively better uranyl desorption effect on the two types of enhanced cross-linked materials, and the eluent concentration of 0.03 M was appropriate. The results of the simulated test on uranium-containing wastewater showed that all composite adsorbents exhibited significant potential for practical applications.