UiO-66/壳聚糖的制备及其对U(VI)的吸附机制

铀矿开采和冶炼等工艺产生大量低浓度铀废水,危害着生态环境和人类健康,从含铀废水中去除铀(VI)迫在眉睫。本文以UiO-66、壳聚糖(CS)为原料,采用交联法制备UiO-66/CS新型复合材料,通过静态吸附实验,考察不同pH值、吸附剂投加量、吸附时间及铀初始浓度等外部因素对U(VI)去除率的影响。通过SEM、FTIR、XPS等对UiO-66/CS材料进行表征分析,揭示吸附剂去除U(VI)的机制。结果表明：在铀初始浓度为5 mg/L,温度为298 K,p H为5,投加量为0.15 g/L,吸附时间120 min条件下,UiO-66/CS对U(VI)的去除率可达90.24%。吸附过程符合准二级动力学模型和Freundlich等温吸附模型。U(VI)吸附去除机制主要是-NH、-COOH、Zr-O、-OH等官能团与U(VI)发生络合作用。     

亚铁铝类水滑石吸附铀的性能与吸附机制

运用超声共沉淀制备了亚铁铝类水滑石(Fe(Ⅱ)-Al LDH),用于处理含U(Ⅵ)废水。实验考察了初始pH、吸附剂投加量、温度、吸附时间以及U(Ⅵ)初始浓度对Fe(Ⅱ)-Al LDH吸附U(Ⅵ)的影响。采用SEM、FTIR、XRD与XPS等手段分析了相关机制。试验表明,Fe(Ⅱ)-Al LDH吸附U(Ⅵ)的最佳pH为6,当温度为25℃,投加量为1.0g/L,U(Ⅵ)初始质量浓度为10mg/L时,对U(Ⅵ)的去除率达到99.98%,反应在120min达到平衡,饱和吸附量为117.13mg/g。Langmuir等温吸附模型和准二级动力学模型(R~2≈1)较好地拟合了吸附过程,Fe(Ⅱ)-Al LDH对U(Ⅵ)的吸附是自发的吸热反应。SEM、FTIR、XPS分析结果表明,吸附前后的Fe(Ⅱ)-Al LDH结构没有发生改变,Fe(Ⅱ)-Al LDH对U(Ⅵ)的吸附是化学吸附为主,氧化还原作用为辅。     

ZIF-8-SiO2的制备及其对U(VI)的吸附

以沸石咪唑酯骨架结构材料ZIF-8及硅酸四乙酯(TEOS)为原料制备ZIF-8-SiO₂复合材料,并采用XRD、SEM、EDS等方法对ZIF-8-SiO₂的结构及吸附U(VI)前后的形貌进行表征,结果表明ZIF-8-SiO₂成功制备且对U(VI)具有良好的吸附作用。以静态吸附实验,分别考察了pH值、时间、温度、溶液初始铀浓度、盐浓度及超高压环境等对ZIF-8-SiO₂吸附性能的影响。由实验结果可得,在初始浓度为80 mg·L?1时,25℃下ZIF-8-SiO₂对U(VI)的最大实际吸附量为498 mg·g?1,根据Langmuir模型拟合结果分析得出,ZIF-8-SiO₂对U(VI)的理论吸附量最高可达678.5 mg·g?1,且在200~500 MPa范围内,压强越高越有利于吸附。通过FTIR、XPS等方法对ZIF-8-SiO₂吸附铀酰离子前后的结构进行分析,探究该吸附过程中可能存在的吸附机制。      

壳聚糖插层有机膨润土的制备及吸附性能研究

采用微波辅助法,以十六烷基二甲基苄基溴化铵及壳聚糖对膨润土进行改性,制备了一种新型的壳聚糖插层有机膨润土材料。通过红外光谱(FTIR)、X-射线衍射(XRD)及扫描电镜(SEM)对膨润土及插层膨润土进行了表征。结果表明壳聚糖已经进入膨润土层间,层间距由1.41nm增大至2.04nm。对该材料吸附水中苯酚的性能进行了研究,结果显示在25℃,pH=6的条件下,最大理论吸附量为73.25mg/g,最大理论吸附量随温度升高而降低。用不同模型对等温线进行了拟合,结果表明等温吸附平衡更符合Langmuir模型。     

改性凹凸棒土吸附剂去除水中的Cr(VI)

以凹凸棒土为载体,合成了乙二胺(EDA)改性凹凸棒土(ATP)吸附剂EDA/ATP复合材料。采用FTIR、TGA对吸附剂进行表征,同时将其应用于对水中Cr(VI)的吸附,研究了溶液初始浓度、吸附时间、溶液pH、Cl?与PO₄3?阴离子浓度对吸附的影响。FTIR和TGA结果表明乙二胺已成功接枝到凹凸棒土表面。吸附实验表明,25℃时EDA/ATP复合材料对Cr(VI)的最大吸附容量为153.78 mg·g?1,吸附在800~900 min内达到平衡,吸附符合Freundlich吸附等温模型和拟二级动力学模型;在初始溶液pH为2~10条件下,随着pH的增加,吸附量先增加再降低,pH为3时,吸附量最大;Cl?对吸附影响较小,PO₄3?对吸附的影响较大,当PO₄3?浓度达到20 mmol·L?1时,Cr(VI)最大吸附量下降了83 mg·g?1;实验表明EDA/ATP可作为一种潜在处理水中Cr(VI)的吸附剂。      

纳米Fe_3O_4/黑曲霉磁性微球对U(Ⅵ)的吸附性能及机制

在Fe_3O_4中加入黑曲霉培养基混合培养制备了Fe_3O_4/黑曲霉磁性微球,通过静态吸附试验,考察了pH值、温度、吸附剂用量、接触时间及U(Ⅵ)初始浓度等因素对Fe_3O_4/黑曲霉磁性微球吸附U(Ⅵ)效果的影响。结果表明:pH值是影响Fe_3O_4/黑曲霉磁性微球去除U(Ⅵ)的重要因素。pH=4、温度为25℃、U(Ⅵ)的初始浓度为10mg/L、Fe_3O_4/黑曲霉磁性微球投加量为1g/L时,Fe_3O_4/黑曲霉磁性微球对U(Ⅵ)的去除率达到98.89%,在吸附15h后趋于平衡。采用SEM、能谱分析、FTIR等手段分析了Fe_3O_4/黑曲霉磁性微球吸附U(Ⅵ)的机制。SEM-EDS结果表明,Fe_3O_4/黑曲霉磁性微球成功合成且呈网状结构;FTIR结果表明,Fe_3O_4/黑曲霉磁性微球与铀发生作用的主要基团有羟基、羧基、酰胺基等。     

离子印迹磁性壳聚糖微球对铀离子的吸附特性

以U(VI)为模板,利用印迹-交联技术制备具有良好吸附性能的离子印迹磁性壳聚糖微球(IMCR)。IMCR粒径为10μm~35μm,磁化强度为29.7 emu/g,对U(VI)吸附最佳pH为5.0,随温度升高,U(VI)吸附容量下降。吸附符合拟二级动力学,且为自发放热过程。吸附等温线符合Langmuir模型,为单分子层吸附。由Dubinin-Radushkevich模型计算的E>8 kJ/mol,表明为化学吸附。IMCR对U(VI)最大吸附容量为187.3 mg/g,高于非印迹树脂(NIMCR 160.8 mg/g),并且有更好的选择性。吸附后的IMCR可用0.5 mol/L EDTA溶液洗脱再生。     

黄原酸化膨润土的制备及脱除亚甲基蓝的性能研究

对膨润土进行改性制得黄原酸化膨润土(XB),通过FT-IR、TG、SEM、粒度分析对XB进行了表征,结果表明,碳硫键接到了膨润土表面,使其亲水性降低,表面积增大。通过XB对亚甲基蓝的吸附试验,表明XB是一种环境友好型吸附剂。考察了亚甲基蓝初始浓度、吸附时间、温度、pH值、吸附剂用量对其吸附性能的影响。结果表明:在25℃,pH=7～8,亚甲基蓝初始浓度100mg/L,XB用量为2g/L,吸附30min时,XB对亚甲基蓝的脱色率达到99.93%,处理后废水可达标排放。     

蔗渣纤维素-海藻酸钙-膨润土多孔微球的制备及其对罗丹明B吸附性能的研究

以蔗渣纤维素、海藻酸钠为三维网络框架,膨润土为吸附功能单元,采用金属离子交联法联合物理包载法制备蔗渣纤维素-海藻酸钙-膨润土多孔微球,研究其对罗丹明B吸附性能,探究其吸附机理。采用扫描电镜(SEM)、X射线衍射(XRD)和热重(TG)等表征手段分别对多孔微球形貌、晶相和热稳定性进行表征。结果表明：在固液比2g/L,染料溶液pH=3,体积为25mL,初始浓度为400mg/L,吸附温度为318K,吸附360min后,吸附量高达87.14mg/g。多孔微球吸附罗丹明B过程符合准二级动力学模型,罗丹明B在多孔微球吸附遵循Langmuir等温线吸附模型。吸附罗丹明B前后,多孔微球为类球形,具有一定孔隙结构;多孔微球中膨润土晶型结构无明显改变,且具有一定热稳定性。     

木质纤维素基纳米复合材料对Pb~(2+)、Cd~(2+)的吸附研究

以原位插层共聚法制备木质纤维素-g-丙烯酸/丙烯酰胺/蒙脱土(LNC-g-AA/AM/MMT)纳米复合材料,采用X射线衍射(XRD)、扫描电镜(SEM)对其结构进行表征。研究在金属离子初始浓度、吸附时间、吸附温度、pH值等不同吸附条件下,LNC-g-AA/AM/MMT纳米复合材料对Pb2+、Cd2+吸附性能的影响。结果表明,当Pb2+、Cd2+初始浓度分别为0.04和0.06mol/L,吸附时间分别为120和60min,吸附温度分别为40和30℃,pH值为5.5时,LNC-g-AA/AM/MMT纳米复合材料对Pb2+、Cd2+的吸附量分别高达504.2和246.9 mg/g。整个吸附过程均符合Langmuir吸附等温线模型和伪二级动力学模型,且是个自发放热的反应过程。同时对最佳条件下吸附饱和的LNC-g-AA/AM/MMT纳米复合材料进行解吸研究,脱附率分别为93.4%和92.9%。     

Chelating agent-free solid phase extraction (CAF-SPE) of uranium,cadmium and lead by Fe-Al-Mn nanocomposite from aqueous solution

Fe-Al-Mn nanocomposite has been synthesized by impregnating MnO₂ with Fe and Al nitrate aqueous solution for preconcentration and determination of Pb (II), Cd (II) and U (VI) ions from aqueous solution. Fourier Transform Infrared spectroscopy (FTIR), X-Ray-diffraction (XRD) and Scanning electron microscopy coupled with energy dispersive X-ray detector (SEM–EDX) were employed to characterize the as-synthesized nanocomposite. The XRD result indicates that the as-synthesized nanocomposite had a crystal size with rhombohedral structure and size of 30.81 nm. FTIR results confirmed the presence of hydroxyl group and Metal–Oxygen vibration in the adsorbent. A sensitive and simple solid-phase preconcentration procedure for the determination of trace amounts of Pb(II) and Cd(II) ions by FAAS and U(VI) ions by Uv–Vis was developed. The adsorption isotherm was formally described by both Langmuir and Freundlich equation with a maximum adsorption capacity of 12.5 (Pb), 12.8(Cd) and 14.9(U) mg g^?1 respectively with preconcentration factor of 15. The limits of detection were 0.09, 0.05 and 0.0097 mg L^?1 and the relative standard deviation for ten replicate measurements were 2.47, 0.979 and 2.04%, for Pb (II), Cd(II) and U(VI) ions, respectively. The recovery of Pb(II), Cd(II) and U(VI) ions were found to be 92.7, 91.3, and 81.76%, respectively. On the basis of these findings, the as-synthesized Fe-Al-Mn nanocomposite was successfully applied as a solid phase extraction for preconcentration and determination of Pb(II), Cd(II) and U(VI) ions in aqueous solution.

     

制备方法对氧化石墨烯氧化程度及对Th(IV)、U(VI)吸附的影响

采用Hummers方法、优化Hummers方法及改进Hummers方法合成氧化石墨烯, 并通过FT-IR、TGA、XRD、XPS、SEM以及元素分析等手段对制备产物进行了表征。结果表明, 利用优化Hummers方法制备得到的氧化石墨烯具有较高的氧化程度。三种产物对Th(IV)、U(VI)的等温吸附实验结果表明, 采用优化Hummers方法制备的氧化石墨烯对Th(IV)的最大吸附量为192.3 mg/g, 相比于Hummers方法制备产物的吸附能力提高了38.5%; 对U(VI)的最大吸附量为156.2 mg/g, 吸附能力提高了28.1%, 三种样品对Th(IV)、U(VI)的吸附都更加符合Langmuir等温吸附模型。此外, 考察了优化Hummers方法制备的氧化石墨烯吸附Th(IV)、U(VI)的动力学和热力学参数, 证实氧化石墨烯吸附Th(IV)、U(VI)符合准二级动力学方程, 是自发吸热行为。     

污泥基生物炭负载纳米零价铁去除Cr(Ⅵ)的性能与机制

针对电镀、冶金、印染等行业产生的含铬废水所导致的环境污染难题,以城市污泥热解获得的污泥基生物炭(SB)为载体,制备了污泥基生物炭负载纳米零价铁(nZVI-SB)材料用于去除水中的Cr(Ⅵ),探究了铁炭质量比、初始pH值、投加量、温度等因素对去除Cr(Ⅵ)的影响。通过SEM-EDS、XRD和XPS等手段对n ZVI-SB去除Cr(Ⅵ)的机制进行分析。结果表明：n ZVI-SB对Cr(Ⅵ)废水具有较好的去除能力。在投加量0.5 g/L、初始pH=2、温度40℃条件下,Fe与SB质量比为1∶1的nZVI-SB(1∶1)对Cr(Ⅵ)吸附量最大为150.60 mg/g。Cr(Ⅵ)去除过程可通过Langmuir吸附等温式与准二级动力学方程进行拟合。nZVI-SB对Cr(Ⅵ)去除机制主要包括吸附、还原和共沉淀。本文表明污泥基生物炭与纳米零价铁可以协同发挥除Cr(Ⅵ)作用。     

Immobilization of 2,2'-dipyridyl onto bentonite and its adsorption behavior of copper(II) ions

In this study, the immobilization of 2,2'-dipyridyl onto bentonite was firstly carried out and it was then used for the adsorption of copper(II) ions from aqueous solutions. The variation of the parameters of pH, contact time, initial copper(II) concentration and temperature were investigated in the adsorption experiments. The XRD, FTIR, elemental and thermal analyses were performed to observe the immobilization of 2,2'-dipyridyl onto natural bentonite. The adsorption data obtained were well described by the Langmuir adsorption isotherm model at all studied temperatures. The results indicated that the maximum adsorption capacity was 54.07 mg g(-1) from the Langmuir isotherm model at 50 degrees C. The thermodynamic parameters indicated that the adsorption process is spontaneous, endothermic and chemical in nature. The kinetic parameters of the adsorption were calculated from the experimental data. According to these parameters, the best-fit was obtained by the pseudo-second-order kinetic model. The results showed that 2,2'-dipyridyl-immobilized bentonite can be used as the effective adsorbent for the removal of heavy metal contaminants.     

SCB-g-MMA的固相接枝制备及其吸附性能

采用固相接枝法将甲基丙烯酸甲酯(MMA)接枝到碱处理后的甘蔗渣(SCB)表面,得到固相接枝产物甲基丙烯酸甲酯接枝甘蔗渣(SCB-g-MMA),并通过XRD、FTIR、13 C NMR、SEM和BET(Brunauer-Emmett-Teller)测试等方法对其结构进行表征分析。将SCB-g-MMA作为亚甲基蓝(MB)的吸附剂,进行吸附性能研究。结果表明:在室温下,MB初始浓度在50~400mg/L范围内,当吸附剂投加量大于等于10g/L时,溶液pH范围在6~12,吸附时间超过40min,SCB-g-MMA对MB的去除率达到99%;当吸附剂投加量为2.5g/L时,对MB的吸附量可达97.3mg/g。SCB-g-MMA对MB吸附动力学和吸附等温线更符合准二级动力学方程和Freundlich等温吸附模型。     

Adsorption of lead(II) ions onto 8-hydroxy quinoline-immobilized bentonite

In this study, the immobilization of 8-hydroxy quinoline onto bentonite was carried out and it was then used to investigate the adsorption behavior of lead(II) ions from aqueous solutions. The changes of the parameters of pH, contact time, initial lead(II) ions concentration and temperature were tested in the adsorption experiments. The XRD, FTIR, elemental and thermal analyses were done to observe the immobilization of 8-hydroxy quinoline onto natural bentonite. The adsorption was well described by the Langmuir adsorption isotherm model at all studied temperatures. The maximum adsorption capacity was 142.94mgg(-1) from the Langmuir isotherm model at 50 degrees C. The thermodynamic parameters implied that the adsorption process is spontaneous and endothermic. The kinetic data indicate that the adsorption fits well with the pseudo-second-order kinetic model. 8-Hydroxy quinoline-immobilized bentonite can be used as well respective adsorbent for the removal of the heavy metal pollutants according to the results.