球形零价铁生物炭吸附Cd(II)的性能和机制

本研究提供了一种一步热解法制备纳米零价铁生物炭的方法。将海藻酸铁在高温缺氧条件下热解制备了球形零价铁生物炭复合材料（ZVIBC），考察了Cd(II)溶液pH、初始浓度、吸附时间、背景离子、空气中老化时间对ZVIBC吸附Cd(II)性能的影响，通过FTIR、XRD、XPS、EDS等方法对ZVIBC以及ZVIBC-Cd(II)进行了表征，研究了ZVIBC对Cd(II)的吸附机理。结果显示：pH对ZVIBC吸附Cd(II)有显著的影响，4为最佳吸附pH条件。ZVIBC吸附Cd(II)的过程符合Langmuir模型，拟合的饱和吸附量为240 mg/g。主要吸附机理为：活性官能团（O—H、C—O、C=C、C=O、COO）与Cd(II)形成配合物，以及Cd(II)与Fe2+生成Cd(OH)2沉淀。     

撞击流-旋转填料床(IS-RPB)制备纳米硫化亚铁的研究

为解决传统间歇式搅拌反应釜制备硫化亚铁产物粒径大、分布不均匀和重复性差的问题,以FeSO_4·7H_2O和Na_2S·9H_2O为原料,在超重力反应器(撞击流-旋转填料床)中成功连续制备了粒径小且均一的硫化亚铁纳米粒子。利用扫描电镜、X射线衍射和激光粒度仪等方法对样品的粒径分布和形貌结构进行表征,考察了反应物初始浓度、超重力因子和撞击初速对硫化亚铁粒径的影响。结果表明,随着反应物初始浓度、超重力因子以及撞击初速的增大,硫化亚铁的粒径先减小后增大,粒径分布逐渐变均匀。最佳制备工艺条件为:反应物初始浓度为0.1 mol/L,物料比为1∶1,超重力因子β=239.8,撞击初速μ=9.43 m~3/s。在此条件下制备的硫化亚铁纯度较高且粒径分布均匀,中位粒径D50为87 nm,90%的硫化亚铁颗粒在150 nm以下,对铬(Ⅵ)离子有较强的吸附能力,最大吸附量为196.85 mg/g。     

共沉淀法合成小粒径单分散Fe3O4纳米颗粒

研究以FeSO4·7H2O和FeCl3·6H2O为原料,NH3·H2O作为沉淀剂,采用共沉淀法制备纳米Fe3O4颗粒,利用IR（红外光谱）、XRD（X射线衍射）等表征手段对割得的纳米颗粒进行了表征。结果表明：制备的纳米Fe3O4粒子粒径较细,且粒径分布较窄。据此找出制备纳米Fe3O4粒子的最佳实验条件为：铁盐溶液浓度为0．5mol／L,沉淀剂溶液浓度为0．2mol／L,Fe^2＋：Fe^3＋：OH^-=1．00：1．00：6．00,反应温度为30℃。制备纳米Fe3O4粒子粒径在10-20mm,且分散性较好;通过XRD谱图可以得出产物为具有立方晶系的纳米Fe3O4粒子。     

Fe_3O_4磁性纳米颗粒外包腐植酸用于有效去除水中重金属

本研究合成了腐植酸(HA)包裹的Fe3O4纳米颗粒(Fe3O4/HA)并将其用于去除水中的重金属离子,包括Hg(I)、Pb(I)、Cd(I)和Cu(I)。以价格低廉、环境友好的铁盐和腐植酸为原料,通过共沉淀方法制备Fe3O4/HA。TOC和XPS的分析结果表明所制备的Fe3O4/HA中约含有11%(w/w)的叶酸,它是含O和N-官能团丰富的组分。TEM成像和激光颗粒尺寸分析证实所制备的Fe3O4/HA(Fe3O4内核约为10 nm)在水溶液中团聚并形成了平均水和半径约为140 nm的聚集体,饱和磁化强度为79.6 emu/g,这种Fe3O4/HA材料在低磁场梯度下几分钟内就可以从水溶液中分离。Fe3O4/HA对重金属离子的吸附在15分钟内就可以达到平衡,其吸附行为符合朗格缪尔吸附模型,且最大吸附容量在46.3~97.7 mg/g范围内。制备的Fe3O4/HA在自来水、天然水、0.1 M HCl和2 M Na OH的酸/碱溶液中都很稳定,Fe(≤3.7%)和HA(≤5.3%)的泄漏率很低。在最优条件下,Fe3O4/HA纳米材料能够去除天然水和自来水中超过99%的Hg(II)和Pb(II)以及超过95%的Cu(II)和Cd(II)。Fe3O4/HA吸附的重金属离子泄露回水溶液的量几乎可以忽略。     

超重力法制备CNT负载MnFe2O4纳米材料及吸附Pb(II)应用

为改善MnFe2O4纳米颗粒在实际应用中的团聚问题，结合多壁碳纳米管(CNT)原位负载，提出超重力法制备CNT负载MnFe2O4纳米材料(MnFe2O4/CNT)。以典型的重金属污染Pb(II)作为研究对象，对其吸附性能进行研究。首先考察了MnFe2O4负载量对Pb(II)吸附容量的影响，确定最佳MnFe2O4负载量为83.3wt%。采用XRD, SEM, N2吸附-脱附比表面分析仪和VSM对最佳MnFe2O4负载量条件下的MnFe2O4/CNT进行表征。MnFe2O4/CNT展现出优异的磁性，其饱和磁化强度为35.85 emu/g，因而可应用于水体中污染物的磁性分离。吸附实验结果表明在初始Pb(II)浓度300 mg/L和溶液pH=6的条件下，Pb(II)在MnFe2O4/CNT上180 min达到吸附平衡，吸附平衡容量为80.7 mg/g，远高于单独的CNT (28.4 mg/g)。动力学研究表明Pb(II)在MnFe2O4/CNT上的吸附符合Elvoch动力学模型，说明吸附机理中存在化学吸附。Freundlich等温线模型能够很好地描述Pb(II)在MnFe2O4/CNT上的吸附过程，其代表发生在非均匀表面的多分子层吸附。另外，吸附等温线实验中获得的MnFe2O4/CNT最大吸附容量为106.2 mg/g，展现出了对重金属Pb(II)优异的吸附性能，在去除溶液中重金属中具有较大的应用潜力。根据X射线光电子能谱分析，表明吸附机理涉及到Pb(II)与MnFe2O4表面羟基的络合。     

离子液体中合成Fe3O4/PANI复合纳米颗粒

以FeCl3.6H2O和FeCl2.4H2O为原料,以水为介质,利用化学共沉淀法,常温下反应合成了Fe3O4纳米粒子,并进一步以Fe3O4纳米粒子为原料,采用原位聚合法分别在H2O和氯代1-丁基-3-甲基咪唑([BMIM]Cl)离子液体中合成了Fe3O4/聚苯胺(PANI)纳米复合粒子,用透射电子显微镜(TEM)、X射线衍射仪(XRD)、热分析仪(TG)、电导率仪、多功能振动样品磁强计对样品的形貌、结构和电磁性能进行了表征。结果表明:在这两种介质中都可以得到核壳型复合颗粒,但离子液体中合成的复合颗粒粒度小、分散性好且聚苯胺的结晶程度高。在离子液体中制备的复合材料与水中相同条件下制得的复合材料相比,电导率及磁性能均有提高。在离子液体中制备磁性导电复合材料是一种绿色高效的工艺。     

纳米固体超强酸SO42-/Fe2O3催化合成没食子酸异戊酯的研究

以FeCl3溶液为原料制备了纳米固体超强酸催化剂SO2-4/Fe2O3,透射电镜(TEM)测定结果表明其粒径约100 nm,探讨了硫酸铵浸渍浓度、催化剂焙烧温度、焙烧时间对催化剂性能的影响.以纳米固体超强酸SO2-4/Fe2O3为催化剂,由没食子酸与异戊醇直接酯化合成了没食子酸异戊酯.通过正交实验研究了影响没食子酸异戊酯产率的主要因素,确定最优实验条件为:醇酸物质的量比为10∶1,催化剂用量为反应物总质量的3.0%,反应时间为3.0 h.此时酯产率达到74.3%.     

超重力环境下O3/Fenton法处理含硝基苯废水

在旋转填充床(RPB)中超重力环境下采用O3/Fenton法处理含硝基苯废水,考察了Fenton试剂投加次数、超重力因子β、液体流量、初始pH值、Fe2+投加量、H2O2与Fe2+摩尔比对硝基苯去除率的影响. 结果表明,在硝基苯浓度175 mg/L、反应温度25℃、气体流量75 L/h、臭氧浓度40 mg/L、分3次投加Fenton试剂、溶液初始pH值4.5、超重力因子β=80、液体流量140 L/h和Fe2+总投加量1 mmol/L、摩尔比H2O2:Fe2+=5、循环处理40 min的条件下,硝基苯去除率和化学需氧量(COD)去除率分别为99.6%和87.6%. 相近条件下,与RPB-Fenton法相比,硝基苯去除率和COD去除率分别提高了36.3%和4.5%,与RPB-O3法相比分别提高了7.2%和47.1%,与BR(鼓泡反应器)-O3/Fenton法相比分别提高了11.3%和47.8%.     

磁性膨润土的制备及其性能

为实现外加磁场下膨润土处理废水后的快速分离,先以FeCl3·6H2O,FeSO4·7H2O等为主要起始原料,采用共沉淀法制备Fe3O4磁流体,再与膨润土复合制备一系列不同Fe3O4载量(质量分数,下同)的磁性膨润土。采用X射线衍射、Fourier红外吸收光谱、扫描电子显微镜、透射电子显微镜、能谱仪、振动样品磁强计对样品进行表征,研究了Fe3O4载量对磁分离回收率,Cu2+,Zn2+,Cd2+的饱和交换吸附量及去除率的影响。结果表明:Fe3O4微粒附载于膨润土表面而形成磁性集合体,磁性膨润土具有超顺磁性,对Cu2+,Zn2+,Cd2+的饱和交换吸附性能及去除率与原膨润土的相当,但随Fe3O4载量增加而降低。Fe3O4载量为25%时,其饱和磁化强度、剩余磁化强度分别为13.344,0.365A·m2/kg,矫顽力为1.232kA/m,磁分离回收率为90.1%。对浓度为5mmol/L的Cu2+,Zn2+,Cd2+的饱和交换吸附量分别为23.0,21.3,18.9mg/g,去除率分别为27.9%,26.6%,14.3%。     

RPB-O_3/Fenton法处理黑索今废水

针对黑索今(RDX)生产工艺中产生的废水成分复杂、难生物降解等特点,用RPB-O3/Fenton法在常温下对RDX生产废水进行了处理,以期寻找出一种高效的处理方法,使其达标排放。首先,考察了超重力因子、H2O2与Fe2+摩尔比、Fenton试剂总投加量及投加次数、液体流量以及反应时间等因素对处理效果的影响;其次,对RPB-O3/H2O2,RPB-O3/Fe2+和RPB-O3/Fenton 3种方法的动力学进行了研究和对比。研究结果表明:在最适宜工艺条件超重力因子为85,Fe2+总投加量为2 mmol/L(分3次投加)、H2O2与Fe2+摩尔比为4、臭氧质量浓度为42.7 mg/L、液体流量为140 L/h时,对700 mL RDX废水处理20 min后,RDX去除率达到97.5%,出水RDX质量浓度为1.25mg/L,COD为35 mg/L,达国家一级排放标准;另外,RPB-O3/H2O2,RPB-O3/Fe2+,RPB-O3/Fenton这3种方法均符合准一级反应动力学,且对比发现,RPB-O3/Fenton法的动力学速率常数最大。     

Preparation and characterization of magnetic polymethylmethacrylate microbeads carrying ethylene diamine for removal of Cu(II), Cd(II), Pb(II), and Hg(II) from aqueous solutions

Magnetic polymethylmethacrylate (mPMMA) microbeads carrying ethylene diamine (EDA) were prepared for the removal of heavy metal ions (i.e., copper, lead, cadmium, and mercury) from aqueous solutions containing different amount of these ions (5–700 mg/L) and at different pH values (2.0–8.0). Adsorption of heavy metal ions on the unmodified mPMMA microbeads was very low (3.6 μmol/g for Cu(II), 4.2 μmol/g for Pb(II), 4.6 μmol/g for Cd(II), and 2.9 μmol/g for Hg(II)). EDA‐incorporation significantly increased the heavy metal adsorption (201 μmol/g for Cu(II), 186 μmol/g for Pb(II), 162 μmol/g for Cd(II), and 150 μmol/g for Hg(II)). Competitive adsorption capacities (in the case of adsorption from mixture) were determined to be 79.8 μmol/g for Cu(II), 58.7 μmol/g for Pb(II), 52.4 μmol/g for Cd(II), and 45.3 μmol/g for Hg(II). The observed affinity order in adsorption was found to be Cu(II) > Pb(II) > Cd(II) > Hg(II) for both under noncompetitive and competitive conditions. The adsorption of heavy metal ions increased with increasing pH and reached a plateau value at around pH 5.0. The optimal pH range for heavy‐metal removal was shown to be from 5.0 to 8.0. Desorption of heavy‐metal ions was achieved using 0.1 M HNO₃. The maximum elution value was as high as 98%. These microbeads are suitable for repeated use for more than five adsorption‐desorption cycles without considerable loss of adsorption capacity. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 81–89, 2000     

Biosorption of cadmium(II) and lead(II) from aqueous solutions using Pleurotus ostreatus immobilized on bentonite

The purpose of this work was to evaluate the potential of a white rot fungi (P. ostreatus) immobilized on bentonite, in a continuous flow removal of trace heavy metals. The procedure is based on the biosorption of Cd(II) and Pb(II) ions on a column of bentonite loaded with dried, dead fungi components prior to their determination by atomic absorption spectroscopy (AAS). Cd(II) and Pb(II) were determined with a relative error of less than 5%. Various parameters such as “pH, amount of adsorbent, eluent type and volume, flow rate of the solution and matrix interference effect” on the retention of the metal ions were investigated. This procedure was applied to Cd(II) and Pb(II) determination in aqueous solutions, including tap water system. The optimum experimental parameters were determined to be pH 5, concentration of 10 mg/L, contact time of 30 min and 0.2 g of adsorbent for a quantitative adsorption of the metals. The optimum flow rate was found to be 2.5 mL/min for all metal ions. Each column can be used up to 20 successive analyses without considerable change in recoveries of metal ions.

The proposed method is excellent as regards simplicity, sensitivity, selectivity, precision, accuracy and column stability.     

Efficient Removal of Hg(II) by Polymer-Supported Hydrated Metal Oxides from Aqueous Solution

Chelating PS-EDTA resins modified by metal (Fe, Al, and Zr) oxides were used as adsorbents to remove Hg(II) from aqueous solutions. The modified resins were characterized by BET, FTIR, and XPS. The amino, carboxylate, and the metal oxides on resins exhibited a synergistic effect for Hg(II) removal. It was observed that the modification of PS-EDTA resin not only increased the adsorption of Hg(II) but also accelerated the adsorption rate of Hg(II). The equilibrium data of Hg(II) were best described by the Freundlich isotherm, and the kinetics were found to follow the pseudo-second-order kinetic model. Also, thermodynamic parameters showed that Hg(II) adsorption was endothermic and spontaneous in nature. The increasing the concentration (0.1–2.0 g/L) of NaNO₃ in Hg(II) solution did not affect the adsorption of Hg(II). Moreover, the competitive adsorption indicated that the modified resins had higher selectivity towards Hg(II) over Cd(II), Pb(II), Zn(II), or Cu(II) in a binary system. All of the above results indicated that the modified resin was an efficient and reusable adsorbent for Hg(II) removal due to its simple preparation, high adsorption capacity, fast adsorption rate, ionic strength independence, high selectivity, and good reusability. These properties are of potential application in the fixed-bed continuous-flow column for Hg(II) removal from wastewaters.     

氨基和羧基功能化磁性微球去除水溶液中Cd(Ⅱ)和Pb(Ⅱ)

以甲基丙烯酸和丙烯酰胺为功能单体,通过悬浮聚合法制备了氨基和羧基双功能化的磁性复合微球(Fe3 O4@SiO2-NH2/COOH),并探讨了其对水溶液中Cd(Ⅱ)和Pb(Ⅱ)的吸附性能.X-射线衍射(XRD)分析表明,制备的磁性吸附剂内核为Fe3 O4.红外光谱(FT-IR)和扫描电镜(SEM)测试表明,氨基和羧基对Fe3 O4@SiO2表面改性成功.吸附试验显示,Fe3O4@SiO2-NH2/COOH吸附Cd(Ⅱ)和Pb(Ⅱ)的最优pH值分别为5.0和5.5,吸附过程均符合动力学准二级模型和Langmuir吸附等温模型,吸附剂对Cd(Ⅱ)和Pb(Ⅱ)最大吸附量分别为207.807 mg/g和168.995 mg/g.实际饮用水样中Cd(Ⅱ)和Pb(Ⅱ)的吸附表明,去除率分别可达97.74％和91.44％.该磁性吸附剂对两种重金属离子吸附量大、去除率高,具有良好的实际应用潜力.     

Kinetic and equilibrium studies of Pb(II) and Cd(II) removal from aqueous solution onto colemanite ore waste

The adsorption characteristics of Pb(II) and Cd(II) onto colemanite ore waste (CW) from aqueous solution were investigated as a function of pH, adsorbent dosage, contact time, and temperature. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the adsorption isotherms. Langmuir model fitted the equilibrium data better than the Freundlich isotherm. The adsorption capacity of CW was found to be 33.6 mg/g and 29.7 mg/g for Pb(II) and Cd(II) ions, respectively. Analyte ions were desorbed from CW using both 1 M HCl and 1 M HNO₃. The recovery for both metal ions was found to be higher than 95%. The mean adsorption energies evaluated using the D-R model indicated that the adsorption of Pb(II) and Cd(II) onto CW were taken place by chemisorption. The thermodynamic parameters (ΔG^o, ΔH^o and ΔS^o) showed that the adsorption of both metal ions was feasible, spontaneous and exothermic at 20-50 °C. Adsorption mechanisms were also investigated using the pseudo-first-order and pseudo-second-order kinetic models. The kinetic results showed that the adsorption of Pb(II) and Cd(II) onto CW followed well pseudo-second order kinetics.     

Sorption of Pb(II), Cd(II) and Zn(II) by iminodiacetate chelating resins in non-competitive and competitive conditions

Two chelating resins (CRs) bearing iminodiacetate (IDA) groups derived from acrylonitrile - divinylbenzene (AN-DVB) copolymers having 10 and 15 wt.% nominal cross-linking degrees and a high mobility of the functional groups caused by the presence of a longer spacer between the matrix and the IDA groups were synthesized and tested as sorbents for heavy metal ions like: Pb(II), Cd(II) and Zn(II) from aqueous solutions by batch and column techniques. Experimental data obtained from batch equilibrium tests have been analyzed by two isotherm models: Freundlich and Langmuir. The overall adsorption tendency of CRs toward Pb(II), Cd(II) and Zn(II), under non-competitive conditions, followed the order: Cd(II) > Pb(II) > Zn(II). Selectivity studies were performed in ternary mixture of Pb(II), Cd(II) and Zn(II) to check if the synthesized CRs can be useful for selective separation of heavy metal cations. The results revealed that the CRs with IDA groups exhibited high selectivity toward Pb(II), both in batch and column techniques. Regeneration of the resins was achieved using 0.1 M HCl solution.     

纳米氧化铁应用于水中镉（Ⅱ）的吸附

以原子吸收光谱法为检测手段，研究了新型纳米Fe2O3材料对水中Cd^2＋的静态吸附性能，考察了影响吸附与解吸的主要因素。结果表明，在pH8．0-9．0范围内，纳米Fe2O3对Cd^2＋具有较好的吸附效果，吸附率可达96％以上。采用0．5-3．0mol／LHNO3可将吸附于纳米Fe2O3上的Cd^2＋定量洗脱。将纳米Fe2O3用于自来水样中低浓度隔的加标回收．结果较满意。     

Preparation and Characterization of the Newly Synthesized Metal‐Complexing‐Ligand N‐Methacryloylhistidine Having PHEMA Beads for Heavy Metal Removal from Aqueous Solutions

The aim of this study was to investigate in detail the performance for removal of heavy metal ions of beads composed of poly(2‐hydroxyethyl methacrylate) (pHEMA) to which N‐methacryloylhistidine (MAH) was copolymerized. The metal‐complexing ligand MAH was synthesized by using methacryloyl chloride and histidine. Spherical beads with an average size of 150–200 μm were obtained by the radical suspension polymerization of MAH and HEMA conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, p(HEMA‐MAH) beads had a specific surface area of 17.6 m²/g. The synthesized MAH monomer was characterized by NMR; p(HEMA‐MAH) beads were characterized by swelling studies, FTIR and elemental analysis. The p(HEMA‐MAH) beads with a swelling ratio of 65%, and containing 1.6 mmol MAH/g, were used in the adsorption/desorption experiments. Adsorption capacity of the beads for the selected metal ions, i. e., Cu(II), Cd(II), Cr(III), Hg(II) and Pb(II), were investigated in aqueous media containing different amounts of these ions (10–750 mg/L) and at different pH values (3.0–7.0). Adsorption equilibria were established in about 20 min. The maximum adsorption capacities of the p(HEMA‐MAH) beads were 122.7 mg/g for Cu(II), 468.8 mg/g for Cr(III), 639.4 mg/g for Cd(II), 714.1 mg/g for Pb(II) and 1 234.4 mg/g for Hg(II). pH significantly affected the adsorption capacity of MAH incorporated beads. The chelating beads can be easily regenerated by 0.1 M HNO₃ with high effectiveness. These features make p(HEMA‐MAH) beads a potential candidate for heavy metal removal at high capacity.