Efficient removal of U(VI) from wastewater by a sponge-like 3D porous architecture with hybrid electrospun nanofibers

Removal of uranium(VI)from nuclear wastewater is urgent due to the global nuclear energy exploitation.This study synthesized novel sponge-like 3D porous materials for enhanced uranium adsorption by combining electrospinning and fibrous freeze-shaping techniques.The materials possessed an organic-inorganic hybrid architecture based on the electrospun fibers of polyacrylonitrile(PAN)and SiO_(2).As a sup-porting material,the surface of fibrous SiO_(2) could be further functionalized by cyano groups via(3-cyanopropyl)triethoxysilane.All the cyano groups were turned into amidoxime(AO)groups to obtain a amidoxime-functionalized sponge(PAO/SiO_(2)-AO)through the subsequent ami-doximation process.The proposed sponge exhibited enhanced uranium adsorption performance with a high removal capacity of 367.12 mg/g,a large adsorption coefficient of 4.0×10^(4)mL/g,and a high removal efficiency of 97.59%.The UO_(2)^(2+)adsorption kinetics perfectly conformed to the pseudo-second-order reaction.The sorbent also exhibited an excellent selectivity for UO_(2)^(2+) with other interfering metal ions.2023 Hohai University.Production and hosting by Elsevier B.V.

Removal of Uranium（Ⅵ） by Fixed Bed Ion-exchange Column Using Natural Zeolite Coated with Manganese Oxide

The adsorption of uranium(Ⅵ)on the manganese oxide coated zeolite(MOCZ)from aqueous solution was investigated in a fixed-bed column.The experiments were conducted to investigate the effects of bed height,flow rate,particle size,initial concentration of uranium(Ⅵ),initial pH,presence of salt and competitive ions.The U-uptake by MOCZ increased with initial uranium(Ⅵ)concentration and bed height,but decreased as the flow rate and particle size increased.In the presence of salt and competitive ions,the breakthrough time was shorter.The adsorption capacity reached a maximum at pH of 6.3.The Thomas model was applied to the experimental data to determine the characteristic parameters of the column for process design using linear regression.The breakthrough curves calculated from the model were in good agreement with the experimental data.The BDST model was used to study the influence of bed height on the adsorption of uranium(Ⅵ).Desorption of uranium(Ⅵ)in the MOCZ column was investigated.The column could be used for at least four adsorption-desorption cycles using 0.1mol.L-1 NaHCO3 solution as the elution.After desorption and regeneration with deionized water,MOCZ could be reused to adsorb uranium(Ⅵ)at a comparable capacity.Compared to raw zeolite,MOCZ showed better capacity for uranium(Ⅵ)removal.

Removal of Cr(Ⅲ) and Cr(Ⅵ) from aqueous solution by adsorption on sugarcane pulp residue

Sugarcane pulp residue (SPR), a waste from sugar-refinery, which possesses a large surface area, can be used for removing chromium (Cr(Ⅲ) and Cr(Ⅵ)) from wastewater. In this work, the kinetics, isotherms of Cr(Ⅲ) and Cr(Ⅵ) adsorption and their removal by SPR were investigated. The results show that the removal percentages of Cr(Ⅵ) and Cr(Ⅲ) increase with increasing SPR dosage and temperature and decrease with increasing SPR particle size and the initial concentration of chromium ions. However, the influence of pH value on the Cr( Ⅵ) removal differs from that of the Cr( Ⅲ) removal. The Cr(Ⅵ) removal percentage decreases with increasing pH values, while the Cr(Ⅲ) removal percentage increases with increasing pH value. The adsorption kinetics of Cr(Ⅵ) and Cr(Ⅲ) well fits with pseudo-second-order model. Langmuir adsorption isotherm can well describe the adsorption phenomena of chromium ions with the maximum adsorption capacity of 0.567 mg/g for Cr( Ⅵ) and 3.446 mg/g for Cr( Ⅲ) . Moreover, SPR reveals higher adsorption capacity for Cr(Ⅲ) than that for Cr(Ⅵ), which implies that SPR has more potential application for Cr(III)-containing wastewater treatment than that for Cr(Ⅵ)-containing wastewater treatment.

Efficient removal of uranium from mice by a novel compound of fullerence multi-macrocyclic polyamine derivatives

Uranium removal efficacy of fullerence multi-macrocyclic polyamine derivatives(C60-MMP),a novel chelating agent,was evaluated in mice.C60-MMP was administrated intravenously into mice at 30 min after the uranium contamination.The molar ratio of chelating ligand/uranium was about 1:1.The results indicate that C60-MMP can effectively prevent accumulation of uranium in liver at 8 h after C60-MMP injection.At 48 h after the last injection,uranium deposition in liver of C60-MMP treated mice is approximately 65%less than that of the control group.C60-MMP reacted positively in promoting the removal of uranium from kidney,and the urinary uranium excretion increased significantly,compared with the control and DTPA-treated mice.However,repeated administration of C60-MMP,and combined injection of DTPA and C60-MMP,did not show desirable effects on uranium removal from mice.It implies that more investigations are needed for the treatment protocols and clinical applications of C60-MMP.

电去离子法(EDI)处理含Cr(Ⅵ)废水

采用电去离子法(EDI)处理模拟含Cr(Ⅵ)废水,考察了电压、pH、电解时间和Cu2+等因素对Cr(Ⅵ)去除率和阴离子交换膜性能的影响。实验结果表明:随着电压的增加,阴离子交换膜对Cr(Ⅵ)的透过率逐渐增大,Cr(Ⅵ)去除率逐渐升高;随着电压的增加,阴离子交换膜对Cr(Ⅵ)的吸附率呈先增大后减小的趋势,20 V时,达到最大,为22.0%;pH为1.0~9.0时,对Cr(Ⅵ)去除率和阴离子交换膜性能的影响不大;在Cr(Ⅵ)初始质量浓度109.5 mg/L、电压20 V、pH 6.0~7.0、电解时间60 min的条件下,Cr(Ⅵ)去除率可达94.4%;Cu^(2+)(初始质量浓度100.3 mg/L)的存在使Cr(Ⅵ)去除率降低至80.2%,降低了14.2个百分点。

Selective removal of Cr(Ⅵ)using polyvinylpyrrolidone and polyacrylamide co-modified MoS_(2) ccomposites by adsorption combined with reduction

Cr(Ⅵ),one of the most hazardous metal pollutants,poses significant threats to the environment and human health.Herein,a novel MoS_(2) composite(MoS_(2)/PVP/PAM)modified by polyvinylpyrrolidone(PVP)and polyacrylamide(PAM)was synthesized to enhance the removal of Cr(Ⅵ).Characterization analysis including SEM,XRD,FTIR,and XPS indicated that PVP and PAM could increase the interlayer spacing and the dispersibility of MoS_(2),and introduce pyrrolic N and amino functional groups.The batch experiments showed that MoS_(2)/PVP/PAM represented excellent Cr(Ⅵ)removal performance over a wide p H range,and exhibited a significantly higher maximum Cr(Ⅵ)adsorption capacity(274.73 mg/g,at p H 3.0,and 298 K)than pure MoS_(2).The adsorption of Cr(Ⅵ)followed Langmuir and pseudo-second-order kinetic model,which was a homogeneous monolayer chemisorption process.MoS_(2)/PVP/PAM showed stable removal of Cr(Ⅵ)in the presence of humic acid(HA),interfering cations and anions at different concentrations.Moreover,it had excellent selectivity for Cr(Ⅵ)(K_(d) value of 1.69×10^(7)m L/g)when coexisting with a variety of competing ions.Multiple characterization revealed that Cr(Ⅵ)was reduced to low toxicity Cr(Ⅲ)by Mo^(4+)and S^(2-),and then chelated on the surface of the adsorbent by pyrrolic N.This research expanded the design concept for MoS_(2) composites by demonstrating the potential of MoS_(2)/PVP/PAM as a promising material for selective elimination of Cr(Ⅵ)in water.

Alcohothermal synthesis of sulfidated zero-valent iron for enhanced Cr(Ⅵ)removal

Sulfidation of zero-valent iron(ZVI)has attracted broad attention in recent years for improving the sequestration of contaminants from water.However,sulfidated ZVI(S-ZVI)is mostly synthesized in the aqueous phase,which usually causes the formation of a thick iron oxide layer on the ZVI surface and hinders the efficient electron transfer to the contaminants.In this study,an alcohothermal strategy was employed for S-ZVI synthesis by the one-step reaction of iron powder with elemental sulfur.It is found that ferrous sulfide(FeS)with high purity and fine crystallization was formed on the ZVI surface,which is extremely favorable for electron transfer.Cr(Ⅵ)removal experiments confirm that the rate constant of SZVI synthesized by the alcohothermal method was 267.1-and 5.4-fold higher than those of un-sulfidated ZVI and aqueous-phase synthesized S-ZVI,respectively.Systematic characterizations proved that Cr(Ⅵ)was reduced and co-precipitated on S-ZVI in the form of a Fe(Ⅲ)/Cr(Ⅲ)/Cr(Ⅵ)composite,suggesting its environmental benignancy.

Removal process and mechanism of hexavalent chromium by adsorption-coupled reduction with marine-derived Aspergillus niger mycelial pellets

In order to remove hexavalent chromium(Cr(Ⅵ))from solutions efficiently,the mycelial pellets with a marine-derived fungus Aspergillus niger as a biosorbent were prepared.The effects of removal process parameters such as solution pH,initial Cr(Ⅵ)concentration and biomass concentration on Cr(Ⅵ)removal process were investigated.The results showed that Cr(Ⅵ)removal rate up to 100%could be achieved under optimized conditions,which indicated the excellent Cr(Ⅵ)removal performance of the Aspergillus niger pellets.As a more important point,the Cr(Ⅵ)removal mechanism was studied,and the results revealed that Cr(Ⅵ)removal was achieved in the adsorption-coupled reduction process.A little of Cr(Ⅵ)was reduced to less toxic trivalent chromium(Cr(Ⅲ))in solution,while some was absorbed on the surface of mycelial pellets.Then they may be reduced on the surface or transferred into cells and then be reduced.The marine-derived A.niger mycelial pellets show properties of easy preparation and separation and cost effectiveness,which are potential biosorbent and reductant in the treatment of trace chromate containing wastewater.

用改性纳米零价铁去除废水中U(Ⅵ)的性能及机制

为了绿色高效处理含铀废水,研究了用液相还原法制备多硫化钙改性纳米零价铁(CPS@nZVI)材料并用于去除溶液中U(Ⅵ),考察了CPS@nZVI对溶液中U(Ⅵ)的去除效果。并通过SEM-EDS、XPS和XRD对材料的形貌和表面物质组成进行表征。结果表明:在溶液pH=3.5、U(Ⅵ)初始质量浓度10.0 mg/L、固液质量体积比0.5 g/1 L、反应温度25℃、反应时间120 min条件下,CPS@nZVI材料对溶液中U(Ⅵ)去除率为98.13%,去除量为19.53 mg/g;SEM-EDS、XPS、XRD表征结果表明,样品主要由Fe~0、FeS组成;反应过程符合准二级动力学模型和Langmuir等温吸附模型,该吸附过程受化学吸附控制,为单分子层吸附;还原过程符合伪一级还原动力学,溶液中的U(Ⅵ)以吸附和还原沉淀2种方式去除。

High Efficient Removal of Trace Molybdenum from Water by FeCl_3:Effects of p H and Affecting Factors in the Presence of Co-existing Background Constituents

The effect of FeCl_3 coagulation-filtration on the removal of trace Mo(Ⅵ) from water is investigated in the p H range of 4. 00 to 9. 00 and the effects of sulfate,silicate,phosphate and humic acid( HA) on the process were determined. Overall,the removal of Mo(Ⅵ) is determined by two factors: the content of Fe intercepted from water( Intercepted Fe) and the affinity between Mo(Ⅵ)( or co-existing background constituents) and adsorption sites. At low p H,where the agglomeration of the iron flocs is limited,the former factor is dominant,so the methods that can promote the agglomeration of the iron flocs,such as increasing the p H,adding co-existing constituents( sulfate,phosphate or HA),can increase the removal of Mo(Ⅵ). While at high p H,the second factor dominated. Increasing the p H weakens the affinity between Mo(Ⅵ) and the iron flocs,and co-existing background constituents( sulfate,phosphate,silicate or HA) compete with Mo(Ⅵ) for adsorption sites,both effects result in a decrease in Mo(Ⅵ) removal. The Mo(Ⅵ) removal efficiency of FeCl_3 in natural water decreases as the p H increases from 4. 00 to 9. 00,and it is better to operate the coagulation process at p H 5.00 in the practical water treatment engineering.

甘蔗渣生物炭吸附-还原Cr(Ⅵ)的反应研究

以甘蔗渣为原材料,在限氧条件下经600℃碳化制备生物炭RC,经800℃碳化制备生物炭HC,分别研究两者对Cr(Ⅵ)的吸附-还原反应。采用扫描电子显微镜-能谱(SEM-EDS)、比表面积和孔隙分析(BET)、傅里叶变换红外光谱(FTIR)、X射线光电子能谱(XPS)和拉曼光谱(RS)等对甘蔗渣生物炭表面性质进行表征,从吸附等温线、吸附动力学等角度探讨甘蔗渣生物炭对Cr(Ⅵ)的吸附-还原反应特征及其机理。结果表明:甘蔗渣生物炭具有丰富的孔隙结构和表面活性基团,且随着碳化温度升高,甘蔗渣生物炭表面孔隙度和芳香化程度增加,而含氧官能团OH、C O等相对含量则降低。HC对Cr(Ⅵ)的吸附-还原去除效果最好,总去除量高达117.28 mg·g^(-1),较RC增加了82.42 mg·g^(-1),其中吸附反应的去除量为76.00 mg·g^(-1),比RC增加了67.99 mg·g^(-1)。随着碳化温度升高,生物炭缺陷程度降低,电子传递能力增强。HC对Cr(Ⅵ)的还原量为87.40 mg·g^(-1),较RC增加了57.03 mg·g^(-1)。吸附等温线和吸附动力学拟合结果显示,甘蔗渣生物炭对Cr(Ⅵ)的吸附更符合拟二级动力学模型。Langmuir模型适用于HC对Cr(Ⅵ)的吸附,Freundlich模型适用于RC对Cr(Ⅵ)的吸附。XPS和FTIR分析结果显示,甘蔗渣生物炭对Cr(Ⅵ)的去除机理为静电吸附、还原和络合作用,其中RC、HC吸附作用的相对贡献率分别为22.98%、64.80%,还原反应的相对贡献率分别为87.12%、74.52%,表明甘蔗渣生物炭对Cr(Ⅵ)的去除过程以还原为主。

Cr(Ⅵ)去除用功能化纤维素纳米材料的结构设计研究进展

以Cr(Ⅵ)为代表的重金属离子是一类常见的水体污染物,它具有微量剧毒、难以降解、迁移性强和易在生物体内累积等特点,可对生态系统和人体健康造成严重的危害。纤维素纳米材料(cellulose nanomaterials,CNM)是地球上储量最丰富的一种纤维素衍生物,具有环境友好、生物相容性高和原料来源丰富等优势,其作为绿色经济的重金属离子吸附材料对促进社会可持续性发展和水污染治理具有重要意义。然而纤维素纳米材料对Cr(Ⅵ)的吸附性能差,需对其进行化学改性和组装以提升其对Cr(Ⅵ)的去除效率。本综述系统地介绍和总结了Cr(Ⅵ)去除用CNM的化学改性策略及其几何结构设计的研究进展,并对目前研究中存在的问题进行总结,对未来的发展趋势进行展望。本综述对高效吸附剂的结构设计具有参考价值。

Extraction of uranium(Ⅵ) with di-(2-ethylhexyl) sulfoxide in toluene

The mechanism of extraction uranium(Ⅵ) with di(2-ethylhexyl) sulfoxide (DEHSO)from aqueous nitric acid media has been studied. The influence of the concentrations of nitricacid, cxtractant, salting-out agent, temperature and complex anions (C2O24-) on the distribution ratio was studied.

固体废弃物吸附含铀(Ⅵ)废水的应用及性能

社会经济的发展和人类活动的进行导致固体废弃物数量和种类不断增加,固体废弃物资源化成为世界范围内的热点话题。在双碳背景下,重视循环经济的发展,废弃物资源化有较大的提升空间。核工业核技术的迅速发展产生了含铀放射性废水,利用固体废弃物制成吸附材料对含铀(Ⅵ)废水处理可达到“以废治废”的目的,缓解环境污染问题,利于可持续发展。归纳了一些主要的可应用在除铀方面的固体废弃物材料,如农林业固体废弃物、工业固体废弃物以及城市固体废弃物;介绍了固体废弃物吸附材料的制备和改性方法以及除铀机理;并对今后铀吸附材料的研究方向进行了展望,指出今后铀吸附材料应向高效吸附、绿色环保、高附加值方向发展。

磷酸三钙去除U(Ⅵ)的性能与机理研究

为了探究磷酸三钙对U(Ⅵ)的吸附性能与机理,以碳酸钙和磷酸氢二铵为原料,采用固相法合成磷酸三钙粉末,并利用X射线衍射仪(XRD)、傅里叶转换红外光谱仪(FTIR)、扫描电子显微镜(SEM)和比表面积分析仪(BET)对其理化特性进行表征。研究pH、固液比、吸附时间、U(Ⅵ)初始浓度、吸附温度等因素对磷酸三钙去除U(Ⅵ)性能的影响。采用动力学吸附、等温吸附、热力学吸附等模型及XRD、FTIR、X射线光电子能谱(XPS)、SEM、能谱仪(EDS)、电感耦合等离子体发射光谱仪(ICP-OES)等表征手段揭示磷酸三钙去除U(Ⅵ)的机理。结果表明:在pH=3.0、固液比0.1 g/L、吸附时间60 min、U(Ⅵ)初始质量浓度120 mg/L、吸附温度308 K的条件下,磷酸三钙对U(Ⅵ)的平衡吸附容量达到999.25 mg/g。该吸附过程符合准二级动力学模型(化学吸附)和Langmuir模型(单层吸附),且为自发吸热过程。磷酸三钙对U(Ⅵ)的去除机理为溶解和沉淀过程:在酸性水溶液中,磷酸三钙溶解出的Ca^(2+)和PO^(3-)_(4)与UO_(2)^(2+)发生沉淀反应,在磷酸三钙表面生成准钙铀云母(Ca(UO_(2))_(2)(PO_(4))_(2)·6H 2O)。以上结果表明:磷酸三钙可作为一种有应用前景的用于处理含U(Ⅵ)废水的吸附材料。

Hierarchical Reduced Graphene Oxide-MnO_(2)@Polypyrrole Coaxial Nanotube Composite Hydrogel as a Potential Adsorbent for Cr(Ⅵ)Removal

A hierarchical reduced graphene oxide-MnO_(2)@polypyrrole coaxial nanotube composite hydrogel was prepared via oxidative polymerization of pyrrole in the presence of MnO_(2)nanotubes,followed by the hydrothermal treatment of graphene oxide and MnO_(2)@polypyrrole coaxial nanotubes.The stable composite hydrogel with a hierarchical network was composed of one-dimensional MnO_(2)@polypyrrole coaxial nanotube and two-dimensional graphene nanosheet and characterized by scanning electron microscope,Fourier transform infrared spectroscopy,X-ray diffraction,Brunauer-Emmett-Teller surface,and X-ray photoelectron spectroscopy measurements.The composite hydrogel can be used as an efficient adsorbent for Cr(Ⅵ)removal due to the synergistic interaction between graphene and MnO_(2)@polypyrrole and the hierarchical structure of the hydrogel.Moreover,the composite hydrogel is easily separated because of its stable monolith,and it is reusable(76.8%of removal ability remaining after five adsorption-desorption cycles).The simple fabrication and cost-effective separation process together with the excellent absorption performance endow the composite hydrogel with great potential for practical wastewater treatment.

铁基微电解材料脱除水中Cr(Ⅵ)的研究进展

工业生产过程中产生的高毒性Cr(Ⅵ)易对人体健康和环境安全构成严重威胁,铁基微电解材料脱除水体Cr(Ⅵ)的研究进展表明,以Fe0、Fe^(2+)和H^(+)将Cr(Ⅵ)还原为Cr(Ⅲ),通过吸附、还原、共沉淀等一系列协同反应,可实现Cr(Ⅵ)无害化处置。综述了铁基微电解材料的原料、制备工艺、Cr(Ⅵ)脱除能效等方面的研究进展,结果表明:在铁碳基体中添加Ni、Cu、Pd等催化金属加速阳极Fe氧化及电子的转移、催化H+的产生、与Fe^(2+)和Fe^(3+)之间的氧化还原反应利于多路径脱除Cr(Ⅵ),显著提高脱铬效率,该工艺有望成为该领域的研究方向,但上述金属的添加制备复杂且导致成本增加。在此基础上,提出了一种以钒钛铁精粉碳热法制备微电解材料的工艺,实现基于钒钛复杂伴生矿矿物特性的综合利用,但其中铁-碳-钒-钛多元耦合体系的协同脱铬机制有待深入研究。

氧化石墨烯/二氧化硅复合材料对铀(Ⅵ)的吸附性能

以氧化石墨烯(GO)、正硅酸乙酯(TEOS)为原料,聚氧乙烯-聚氧丙烯-聚氧乙烯(P123)为表面活性剂,利用TEOS水解成SiO_2合成了氧化石墨烯/二氧化硅复合材料(GOS)。通过静态实验,探讨pH、GOS投加量、吸附时间和U(Ⅵ)初始浓度对GOS吸附U(Ⅵ)的影响,采用傅里叶变换红外光谱(FTIR)、X-射线衍射(XRD)、扫描电子显微镜(SEM)和能谱分析(EDS)对GOS进行表征,并探讨其吸附U(Ⅵ)的机理。结果表明:当溶液pH为6,投加量为0.2 g/L,吸附时间为120 min时,GOS吸附U(Ⅵ)效果最佳;吸附过程较好地拟合准二级动力学模型(R2≈1)和Freundlich等温模型(R2≈1);Si O_2成功与GO复合,GOS对U(Ⅵ)具有很好的吸附性能,其吸附U(Ⅵ)前后自身结构并未发生变化,其对U(Ⅵ)的吸附机理以—COOH、—OH的离子交换作用为主,Si—OH的络合反应并存。

交联海藻酸钠固定化的腐殖酸多孔性薄膜对铀(Ⅵ)的吸附性能及机理

采用戊二醛交联海藻酸钠固定化的腐殖酸,制备得到多孔性薄膜(GA-HA/SA),用于去除含铀废水中的铀(Ⅵ)。通过静态吸附实验,研究了pH值、初始浓度、接触时间、温度对GA-HA/SA吸附U(Ⅵ)效果的影响,进行了吸附过程的热力学与动力学分析;通过红外光谱(FTIR)、扫描电镜(SEM)、X射线能谱(EDS)探讨了相关吸附机理。实验结果表明,pH值为6时吸附效果最好,吸附在60min基本达到平衡。吸附过程符合Langmuir和Dubinin-Radushkevich(D-R)等温模型;25℃时,最大吸附容量为312.5mg·g-1。吸附动力学过程符合准二级速率方程(R2>0.99),吸附速率的控速步骤为颗粒内扩散。GA-HA/SA对U(Ⅵ)的吸附是自发的吸热反应。SEM-EDS、FTIR和D-R模型分析结果表明,与U(Ⅵ)相互作用的基团主要是羧基,且GA-HA/SA吸附U(Ⅵ)的机理表现为离子交换。