AOPAN/PA-66复合纳米纤维膜的制备及对金属离子的吸附性能

采用双喷头电纺丝技术,将尼龙(PA-66)纤维增强的聚丙烯腈(PAN)纳米纤维膜(PAN/PA-66)与盐酸羟胺进行偕胺肟化反应,制备了一种偕胺肟化聚丙烯腈/尼龙复合纳米纤维膜(AOPAN/PA-66).通过红外光谱及扫描电子显微镜等方法研究了偕胺肟化前后纳米纤维膜的组成、形貌和力学性能;并考察了AOPAN/PA-66复合纳米纤维膜对铜离子和铅离子的吸附性能.结果表明,AOPAN/PA-66复合纳米纤维膜的抗拉伸强度及断裂伸长率分别为4.73 MPa和30.76%,对Cu(Ⅱ)及Pb(Ⅱ)的吸附量分别为67.5和75.4 mg/g.     

静电纺聚吲哚纳米纤维的制备及其对镉离子的吸附行为

以无水氯化铁为氧化剂,采用化学氧化还原法合成了聚吲哚,利用静电纺丝技术制备了聚吲哚导电纳米纤维材料,研究了聚吲哚纳米纤维对重金属Cd2+的吸附行为.FTIR和NMR测试结果表明,化学氧化还原过程中吲哚的聚合是发生在吲哚单体的C2、C3位置.SEM和TEM观察表明,聚吲哚纳米纤维表面较光滑,呈圆柱状、没有珠节;纤维无规分布,平均直径约为145 nm;聚吲哚纳米纤维的比表面积非常高,达73.45 m2/g,其对重金属Cd2+具有良好的吸附能力,在p H=6时其对Cd2+平衡吸附量最大,约为140.36 mg/g,平衡吸附时间约为50 min.热力学分析表明聚吲哚纳米纤维对Cd2+的吸附行为用Freundlich模型描述更合理,动力学分析表明聚吲哚纳米纤维对Cd2+的吸附比较符合准二级动力学模型.再生10次后,其吸附量为100.67mg/g,是最大值的71%,是一种潜在的重金属Cd2+高效吸附材料.     

水杨酸型螯合吸附材料对重金属离子的吸附性能

将5-氨基水杨酸接枝到PGMA/SiO2微粒的聚甲基丙烯酸缩水甘油酯(PGMA)大分子链上,成功制备了一种新型螯合吸附材料ASA-PGMA/SiO2。采用静态法研究了ASA-PGMA/SiO2对重金属离子Cu2+、Cd2+、Zn2+、Pb2+的吸附性能,结果表明其对Cu2+、Cd2+、Zn2+、Pb2+具有很强的螯合吸附能力,吸附容量分别可以达到0.42、0.40、0.35、0.31mmol/g。体系的pH对吸附容量影响较大,吸附行为服从Langmuir和Freundlich吸附模型。使用0.1mol/L的盐酸溶液就可实现重金属离子的解吸。通过反复吸附-解吸实验证明ASA-PGMA/SiO2具有良好的重复使用性能。     

纳米氢氧化铝-聚丙烯酰胺复合絮凝剂对镉离子的吸附研究

采用响应面法对纳米氢氧化铝-聚丙烯酰胺复合絮凝剂吸附Cd(II)过程进行了拟合和优化,分别以pH值、温度和Cd(II)浓度为自变量,研究了其对响应值镉离子最大吸附量的影响,并通过吸附动力学方程和吸附等温线数据对吸附机理进行了探讨。结果表明,采用响应面法对pH值、温度和Cd(II)浓度3个自变量进行优化后得出最大吸附量为79.07mg/g,其最优条件为:pH 6.35,镉离子浓度91.36mg/L,温度50℃;氢氧化铝-聚丙烯酰胺对Cd(II)的吸附在120min内达到平衡,且吸附动力学数据符合准二级动力学模型,表明吸附过程包含化学吸附;吸附速率的控制步骤是吸附脱附平衡步骤;吸附等温线数据与Langmuir吸附等温模型相一致,表明镉离子在氢氧化铝-聚丙烯酰胺表面形成的是单层吸附层。     

硫脲基纳米螯合纤维对水溶液中Cd(Ⅱ)的吸附和密度泛函理论计算

以聚丙烯腈为原料, 利用静电纺丝技术和化学接枝制备得到硫脲基纳米螯合纤维, 并用于水溶液中 Cd(Ⅱ)的去除. 结合样品的表征和密度泛函(DFT)理论计算结果, 揭示了所制备纳米纤维材料对Cd(Ⅱ)的吸附机理. 借助静态吸附和动态吸附实验, 考察了硫脲基纳米螯合纤维对Cd(Ⅱ)的吸附性能. 结果表明, 纳米纤维吸附材料对Cd(Ⅱ)的最大吸附容量可达349.46 mg/g, 吸附过程在90 min以内即可达到基本平衡. 整个吸附过程符合准二级动力学模型和Langmuir等温吸附模型. 硫脲基纳米螯合纤维吸附Cd(Ⅱ)的吸附机理为表面配位络合, 增加纳米纤维表面硫脲基团的含量是提高吸附容量的重要途径. 该吸附材料经6次循环使用后, 最大动态吸附容量并未发生明显改变.     

新型支化聚乙烯亚胺螯合树脂的制备及吸附性能研究

在聚乙烯亚胺(PEI)的胺基上接枝4种不同的侧链,制备出4种新型的螯合树脂。研究这些螯合树脂对重金属离子Hg(II)、Cd(II)、Co(II)、Cu(II)、Zn(II)、Pb(II)、Mg(II)的吸附性能以及选择性吸附,并对温度对Cu(II)的最大吸附量的影响进行了研究。结果表明:新型的螯合树脂对Hg(II)有很好的吸附性能和吸附选择性,对Cu(II)、Cr(III)重金属离子也有较好的吸附性能,随着温度的升高,树脂对金属离子的吸附量逐渐上升。     

球形立方相纳米二氧化铈-ICP-MS法同时测定痕量铅和镉

采用室温固相法合成球形立方相纳米CeO2,建立了纳米CeO2富集分离,ICP-M S同时测定痕量Pb(Ⅱ)和Cd(Ⅱ)的方法。在pH 7.0,10 mg CeO2,吸附15min后,纳米CeO2对Pb(Ⅱ),Cd(Ⅱ)的吸附率均可达100%;以2mL 0.05 mol/L HCl溶液为洗脱剂、洗脱20 min后,对Pb(Ⅱ)和Cd(Ⅱ)的洗脱率可分别达到98%和95%以上;纳米CeO2对Pb(Ⅱ),Cd(Ⅱ)的最大静态吸附容量分别为496.9μg/g和243.1μg/g,富集倍数均可达250倍,共存离子影响小。优化ICP-MS仪器工作条件,选择205Bi和115In为在线内标进行Pb(Ⅱ)和Cd(Ⅱ)的测定,检出限分别为1.7 pg/mL和9.2 pg/mL,RSD分别为4.8%和0.94%。方法应用于实际水样,回收率分别为Pb(Ⅱ)93.6%~106.4%,Cd(Ⅱ)96.2%~108.9%。     

聚(丙烯酸-co-丙烯酰胺)/蒙脱土/腐殖酸钠复合物对Pb2+的吸附性能

用制备的聚(丙烯酸-co-丙烯酰胺)/蒙脱土/腐殖酸钠复合吸附剂,研究了溶液pH值、吸附时间和Pb2+溶液初始浓度等因素对重金属Pb2+的吸附性能,探讨了复合吸附剂对Pb2+的吸附机理。结果表明,在pH值为6.0、吸附时间2 h、Pb2+溶液初始浓度0.01 mol/L和吸附剂用量0.10 g的条件下,复合吸附剂对Pb2+的吸附量达到364.05 mg/g,平衡所需的时间为15 min。与蒙脱土相比,复合吸附剂具有更高的吸附容量和更快的吸附速率。     

以镍铬合金为基体的铋膜电极的构建及其应用

采用循环伏安法以镍铬合金为基体构建了铋膜/镍铬合金电极,以扫描电镜表征其表面形貌,利用线性扫描伏安法研究了Pb(II)、Cd(II)在该电极上电化学行为。结果表明:在0.20 mol/L HAc-NaAc缓冲溶液(pH4.5)中,该电极对Pb(II)、Cd(II)离子有较好的电催化活性,Pb(II)、Cd(II)的阳极溶出峰电流与其浓度分别呈良好的线性关系,检出限分别为6.39μg/L和3.52μg/L。     

交联羧甲基魔芋葡甘聚糖吸附重金属离子的研究

以异丙醇为分散剂,环氧氯丙烷为交联剂,在碱性介质中由一氯乙酸和魔芋葡甘聚糖(KGM)反应,制备了取代度为0.265和0.550的两种交联羧甲基魔芋葡甘聚糖(CMKGM),并将其用于吸附溶液中Cu2 、Pb2 和Cd2 。结果表明,CMKGM对3种重金属离子的吸附约在20min内达到平衡,与金属离子类型无关,吸附遵从二级动力学方程;pH对吸附量影响较大,适宜范围为5~6;吸附能较好地服从Langmuir等温吸附方程,CMKGM(DS=0.550)吸附Pb2 的最大吸附容量(Qm)为41.7mg/g,Langmuir常数(b)为0.305mg/L,均大于Cu2 和Cd2 相应值;再生后的CMKGM吸附性能好,脱吸附百分率高。     

Adsorption of Zinc and Lead Ions from Aqueous Solutions Using Chitosan/Polyvinyl Alcohol Membrane Incorporated via Acid-Functionalized Carbon Nanotubes

Carbon nanotubes were synthesized via the chemical vapor deposition method using cyclohexanol and ferrocene as carbon precursor and catalyst, respectively, and then they are functionalized with acid treatment. Chitosan/polyvinyl alcohol adsorptive membrane incorporated with carbon nanotubes (CS/PVA-CNTs membrane) was prepared via the solution casting method. The CS/PVA-CNTs membrane was employed for adsorption of lead and zinc ions from aqueous solutions. Various isotherms and kinetic models were applied to fit the experimental data. It was found out that adsorption behavior of the heavy metal ions using CS/PVA-CNTs membrane match well with the Freundlich isotherm and the pseudo-first-order kinetic models.     

Preparation and characterization of nanocomposite,silica aerogel,activated carbon and its adsorption properties for Cd (II) ions from aqueous solution

A novel composite adsorbent, silica aerogel activated carbon was synthesized by sol-gel process at ambient pressure drying method. The composite was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Nitrogen adsorption/desorption isotherms (BET).In the present study, the mentioned adsorbent was used moderately for the removal of cadmium ions from aqueous solutions and was compared with two other adsorbents of cadmium, activated carbon and silica aerogel. The experiments of Cd adsorption by adsorbents were performed at different initial ion concentrations, pH of the solution, adsorption temperature, adsorbent dosage and contact time. Moreover, the optimum pH for the adsorption was found to be 6.0 with the corresponding adsorbent dosage level of 0.1 g at 60 °C temperature. Subsequently, the equilibrium was achieved for Cd with 120 min of contact time.Consequently, the results show that using this composite adsorbent could remove more than 60% of Cd under optimum experimental conditions. Langmuir and Freundlich isotherm model was applied to analyze the data, in which the adsorption equilibrium data were correlated well with the Freundlich isotherm model and the equilibrium adsorption capacity (q_e) was found to be 0.384 mg/g in the 3 mg/L solution of cadmium.     

Assembly of well-aligned multiwalled carbon nanotubes in confined polyacrylonitrile environments: electrospun composite nanofiber sheets

Highly oriented, large area continuous composite nanofiber sheets made from surface-oxidized multiwalled carbon nanotubes (MWNTs) and polyacrylonitrile (PAN) were successfully developed using electrospinning. The preferred orientation of surface-oxidized MWNTs along the fiber axis was determined with transmission electron microscopy and electron diffraction. The surface morphology and height profile of the composite nanofibers were also investigated using an atomic force microscope in tapping mode. For the first time, it was observed that the orientation of the carbon nanotubes within the nanofibers was much higher than that of the PAN polymer crystal matrix as detected by two-dimensional wide-angle X-ray diffraction experiments. This suggests that not only surface tension and jet elongation but also the slow relaxation of the carbon nanotubes in the nanofibers are determining factors in the orientation of carbon nanotubes. The extensive fine absorption structure detected via UV/vis spectroscopy indicated that charge-transfer complexes formed between the surface-oxidized nanotubes and negatively charged (-CN[triple bond]N:) functional groups in PAN during electrospinning, leading to a strong interfacial bonding between the nanotubes and surrounding polymer chains. As a result of the highly anisotropic orientation and the formation of complexes, the composite nanofiber sheets possessed enhanced electrical conductivity, mechanical properties, thermal deformation temperature, thermal stability, and dimensional stability. The electrical conductivity of the PAN/MWNT composite nanofibers containing 20 wt % nanotubes was enhanced to approximately 1 S/cm. The tensile modulus values of the compressed composite nanofiber sheets were improved significantly to 10.9 and 14.5 GPa along the fiber winding direction at the MWNT loading of 10 and 20 wt %, respectively. The thermal deformation temperature increased with increased MWNT loading. The thermal expansion coefficient of the composite nanofiber sheets was also reduced by more than an order of magnitude to 13 x 10(-6)/ degrees C along the axis of aligned nanofibers containing 20 wt % MWNTs.     

Preparation of Ag-MnFe2O4-bentonite Magnetic Composite for Pb(Ⅱ)/Cd(Ⅱ) Adsorption Removal and Bacterial Inactivation in Wastewater

An Ag-MnFe₂O₄-bentonite composite was synthesized by a chemical co-precipitation method and used for adsorption removal of Pb(Ⅱ), Cd(Ⅱ) and disinfection. The result of X-ray diffraction indicate that the diffraction peaks of MnFe₂O₄ and Ag can be perfectly indexed to the cubic spinel MnFe₂O₄(JCPDS No.88-1965) and metallic Ag(JCPDS No.41-1402), respectively. The results of scanning electron microscopy and energy dispersive X-ray spectroscopy manifest the deposition of MnFe₂O₄ and Ag on the bentonite surface and the presence of Mn, Fe and Ag. The result of X-ray photoelectron spectroscopy displayed that the composition of Ag-MnFe₂O₄-bentonite was Mn(Ⅱ), Fe(ⅡI) and metallic Ag. The analysis of Brunauer-Emmett-Teller showed that the specific surface area of Ag-MnFe₂O₄-bentonite was the largest compared with that of bentonite, MnFe₂O₄ and MnFe₂O₄-bentonite. Thermodynamic studies revealed that the adsorption of Pb(Ⅱ) and Cd(Ⅱ) ions was spontaneous and endothermic. Langmuir model showed an adsorption capacity of 129.87 mg/g for Pb(Ⅱ) and 48.31 mg/g for Cd(Ⅱ) ions. The adsorption kinetics of Pb(Ⅱ) and Cd(Ⅱ) ions onto Ag-MnFe₂O₄-bentonite can be best described by a pseudo-second-order model. The adsorption rate constant of the pseudo-second-order model was 0.0019 g·mg^-1·min^-1 for Pb(Ⅱ) and 0.0065 g·mg^-1·min^-1 for Cd(Ⅱ) ions. In addition to the adsorption experiment, the antibacterial properties of Ag-MnFe₂O₄-bentonite were studied through plate count method. Gram-negative(G-) bacteria Escherichia coli and Gram-positive(G+) bacteria Lactobacillus plantarum were used to test the antibacterial properties. The results showed that the composite demonstrated excellent antibacterial activity. Thus, Ag-MnFe₂O₄-bentonite can be employed as an adsorbent as well as an antimicrobial agent.     

Adsorption of cadmium and lead from palm oil mill effluent using bone-composite: optimisation and isotherm studies

The adsorption of Cd and Pb ions from palm oil mill effluent on a mesoporous-activated cow bone composite powder has been investigated. Adsorbent was developed from cow bones, coconut shells and zeolite. The composite examined in the present work has a BET surface area of 248.398 m²/g. The optimisation of the removal efficiency of the heavy metals was investigated using central composite design and analysed using response surface methodology. The analysis of variance of the quadratic model signified that the model suitably predicted the uptake of the heavy metal ions at a 95% confidence level. The optimal operating condition was recorded at pH 4, 50 rpm, within 24 h and 1 mm of particle size and 12.5 gL^?1 of adsorbent dosage. The characteristics of the composite were investigated using the Fourier transform irradiation. The morphology and chemical composition of composite was examined using the scanning electron microscopy equipped with energy dispersive x-ray. Characterisation study was conducted before and after the adsorption process. The results obtained illustrated that the removal of cadmium and lead from POME was influenced by the functional groups available on the surface of the composite. The carboxyl and hydroxyl groups are mainly responsible for the removal of cadmium and lead through chelating process. The point of zero charge (pH_pzc) revealed that the adsorbent contained acidic sites with negatively charge surface which influenced the adsorption process. The experimental data of the heavy metals of Cd and Pb investigated were fitted to the Langmuir and Freundlich models. The result revealed that the adsorption equilibrium data fitted better to the Langmuir model for the adsorption Cd and to the Freundlich model for the adsorption of Pb.     

Adsorption of Cd(II) Ions onto Activated Carbon Prepared from Hazelnut Husks

In this study, a batch adsorption of Cd(II) ions onto activated carbon (AC) produced from hazelnut husks were investigated. The factors controlling the adsorption process such as initial pH, agitation time, dosage and initial concentration have been examined. The AC was showed a high affinity to Cd(II) ions at pH values between 5.0 and 7.0. The equilibrium time was found to be 300 minutes. Cd(II) adsorption equilibrium was analyzed with both Langmuir and Freundlich isotherm equations and it was found that Langmuir equations fitted well with the experimental data. Maximum Cd(II) adsorption capacity of AC was calculated to be 20.9 mg g^?1. Cd(II) adsorption kinetics described well with the pseudo second order model. The activated carbon prepared from hazelnut husks is efficient sorbent material for the removal of Cd(II) ions from aqueous solutions.     

二乙烯三胺改性多壁碳纳米管对溶液中Au(Ⅲ)和Pd(Ⅱ)的吸附

以二乙烯三胺(DETA)为改性剂, 对多壁碳纳米管(MWCNTs) 进行共价键修饰,合成了一种对Au(Ⅲ)和Pd(Ⅱ)有选择性的吸附剂MWCNTs-DETA, 并对Au(Ⅲ)和Pd(Ⅱ)的吸附参数进行了研究和优化. 结果表明, 最佳洗脱剂浓度为1.0 mol/L 硫脲-1.0 mol/L 盐酸, Au(Ⅲ)和Pd(Ⅱ)的洗脱率分别为94.48%和89.06%, 最佳条件下Au(Ⅲ)和Pd(Ⅱ)的饱和吸附容量分别为50.45和25.68 mg/g. 在对吸附等温线的考察中, Au(Ⅲ)拟合Langmuir等温线较好, 而Pd(Ⅱ)则拟合Freundlich等温线较好. 吸附动力学均拟合二级模型较好.     

Crosslinked chitosan nanofiber mats fabricated by one-step electrospinning and ion-imprinting methods for metal ions adsorption

The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats were fabricated by one-step electrospinning and ion-imprinting methods and their application as adsorbents for metal ions was also investigated.The resulting chitosan nanofiber mats were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and thermal gravimetric analysis(TGA).The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats were used as adsorbents for the removal of Pb(Ⅱ)ions from aqueous or acid solutions.The effects of p H values,contact time,content of crosslinker(glutaraldehyde)on Pb(Ⅱ)ions adsorption were studied.The results indicated that the Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats had the highest adsorption capacity of 110.0 mg/g at p H 7.The kinetic study demonstrated that the adsorption of Pb(Ⅱ)ions followed the pseudo-second-order model.The equilibrium isotherm data showed that the Langmuir model was the most suitable for predicting the adsorption isotherm of the studied system.The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats had good adsorption selectivity,which illustrates the equilibrium adsorption capacity in the order of Pb(Ⅱ)Cu(Ⅱ)Zn(Ⅱ)Cd(Ⅱ)Ni(Ⅱ).The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats were stable and had good reuse ability.     

Cd2+和Ni2+在粉煤灰上的吸附特性

考察了粉煤灰对Cd2+和Ni2+的单组分吸附和双组分吸附性能。结果表明,粉煤灰可有效吸附水溶液中的Cd2+和Ni2+,去除率随pH升高而增加。吸附约60min后趋于平衡。粉煤灰对Ni2+的吸附容量高于Cd2+。单组分吸附平衡符合Freundlich模型和Redlich Peterson (R P)模型。双组分吸附时,Ni2+和Cd2+之间存在明显的竞争吸附效应;随干扰离子浓度升高,竞争吸附效应增强。不同模型拟合结果表明,双组分吸附平衡符合Freundlich竞争吸附模型。脱附实验表明,Cd2+比Ni2+易于脱附;0.1mol/L HCl、0.1mol/L HNO3 和0.05mol/L H2SO4的脱附效果接近,对Cd2+脱附率>60%,对Ni2+脱附率>35%。     

A Novel Hollow Carbon@MnO2 Electrospun Nanofiber Adsorbent for Efficient Removal of Pb2+ in Wastewater

Lead ion(Pb²⁺) is one of the most hazardous heavy metal ions in aquatic environments. Carbon materials and manganese dio-xide(MnO₂) have been shown to be prospective adsorbents to cope with the lead pollution. In this study, a novel hollow carbon@MnO₂ composite nanofiber adsorbent was prepared by the combination of electrospinning and carbonization. The PAN nanofiber membrane is subjected to a pre-oxidation and carbonization process, and then the obtained carbon nanofibers react with KMnO₄ solution during the hydrothermal process to develop the hollow carbon@MnO₂ nanofibers. The hollow carbon@MnO₂ nanofibers displayed a higher adsorption capacity of Pb²⁺ than carbon and MnO₂/PDA/PAN nanofibers. The maximum adsorption capacity toward Pb²⁺ by hollow carbon@MnO₂ nanofibers was 460.83 mg/g. After 5 adsorption-desorption cycles, the carbon@MnO₂nanofibers had a good recyclability and the removal efficiency remained 81.47%. Moreover, the removal efficiency of the hollow composite nanofibers for Pb²⁺ from real wastewater could reach 94.37%. This work shows a strategy for synthetics of the hollow carbon@MnO₂ nanofibers, which exhibits a promising potential in actual wastewater treatment.