水葫芦对水溶液中Cu2+和Pb2+的吸附研究

采用水葫芦作为生物吸附剂去除溶液中的Cu2+和Pb2+,针对pH、吸附剂投加量、重金属初始含量、温度及吸附时间等影响吸附的主要因素进行了实验研究,探讨了等温吸附、吸附热力学及动力学。结果表明,pH是影响吸附效果的重要因素,在pH为2~6时,随着pH的增加,重金属离子的去除率也相应的升高。水葫芦对Cu2+和Pb2+的吸附速度很快,80min左右即可达到平衡,吸附过程符合准2级动力学模型;利用Langmuir等温方程拟合得到水葫芦对Cu2+和Pb2+的最大吸附量分别为26.39、81.63mg/g;吸附热力学参数ΔG、ΔH均小于0,表明吸附是一个自发放热的过程。经3次解吸后,水葫芦仍然保持着较高的吸附性能,在重金属废水处理方面有很好的应用前景。     

吸附剂量对合成沸石吸附混合重金属的竞争效果

利用粉煤灰合成的沸石吸附混合重金属Pb2+、Cu2+、Cd2+离子,考察吸附剂量与初始浓度对合成沸石吸附混合重金属离子的竞争吸附效果影响。结果表明:吸附剂量对合成沸石吸附Pb2+、Cu2+、Cd2+的去除率与饱和吸附量影响显著。合成沸石对3种重金属的去除率随着吸附剂投加量的增加而不断升高。当初始浓度为50 mg/L与100 mg/L时,合成沸石对3种重金属离子Pb2+、Cu2+、Cd2+的竞争吸附顺序均为:PbCuCd。合成沸石对混合重金属Pb2+、Cu2+、Cd2+的饱和吸附量随吸附剂量的增加而不断下降。     

二乙烯三胺基木质素吸附Cu2+、Ni2+的性能研究

以木质素与二乙烯三胺原料,通过环氧氯丙烷交联,制得一种新型金属离子吸附剂二乙烯三胺基木质素,通过吸附实验考察了pH、吸附时间及重金属离子浓度对其吸附Cu2+、Ni2+的影响。在pH=5,温度25℃的条件下,二乙烯三胺基木质素对Cu2+、Ni2+的饱和吸附量为44.84mg/g、34.13 mg/g,吸附符合二级动力学吸附方程,吸附过程比较符合Langmuir型等温吸附曲线。     

废弃茶叶对水中Zn~(2+)、Cd~(2+)、Cu~(2+)的吸附研究

通过废弃茶叶对水溶液中的Zn2+、Cd2+、Cu2+的吸附实验,讨论了影响茶叶末吸附重金属的初始浓度、吸附时间、pH等影响因素。结果表明,在30 min内,废弃茶叶末对Zn2+、Cd2+、Cu2+3种金属离子的吸附达到最大,最佳pH因金属的不同而有所差异。处理单组分金属离子水溶液时,3种离子的吸附量和吸附率的大小顺序均为Cu2+Cd2+Zn2+。而处理3种金属离子的多组分溶液时,其吸附量和吸附率的顺序则为Cd2+Cu2+Zn2+。     

天然膨润土吸附水中Pb2+的影响因素和动力学规律

通过静态实验探讨了膨润土用量、Pb2+初始质量浓度、初始pH值、温度等对天然膨润土吸附水中Pb2+的影响和其吸附动力学规律。结果表明,随着温度或Pb2+初始质量浓度的增加,天然膨润土对Pb2+的吸附量增加;但随着膨润土用量的增加,吸附量减小。在pH值为3～7时随着pH值的增加,吸附量增加。此外,天然膨润土吸附Pb2+的的动力学规律符合Lagergren准二级反应模型,并且吸附速度较快,吸附60min后基本达到平衡。     

松果对废水中Cu~(2+)、Pb~(2+)、Zn~(2+)的吸附特性研究

以松果作为吸附剂进行了去除废水中Cu2+、Pb2+、Zn2+的吸附及解吸试验,研究了溶液pH值、吸附剂投加量、反应时间、溶液初始浓度对吸附效果的影响,以及不同pH值对达到吸附平衡的松果的解吸影响。结果表明:当pH值为5.0～5.5,Cu2+、Pb2+、Zn2+初始质量浓度约为25 mg/L时,吸附剂的最佳投加量分别为3、1.5、3 g/L,去除率分别为55.32%、86%、39.96%。3种重金属离子的吸附动力学方程符合Lagergren准二级动力学方程,R2均大于0.998。等温吸附研究表明:Freundlich方程能较好地描述Cu2+的等温吸附过程,Langmuir方程则能更好地描述Pb2+和Zn2+的吸附过程,用Langmuir方程拟合等温吸附数据得出松果对Cu2+、Pb2+、Zn2+的最大吸附量分别为9.10、31.65和9.60 mg/g。强酸是一种理想的Cu2+和Zn2+解吸剂。     

改性火山岩颗粒吸附处理含Cu2+和Zn2+重金属废水影响因素研究

以改性火山岩颗粒作为吸附材料,处理含Cu2+和Zn2+重金属废水,探讨了pH、温度、改性火山岩投加量、吸附时间对吸附性能的影响。结果表明,当pH在3～6之间时,随着pH的增大,改性火山岩颗粒对Cu2+和Zn2+去除率显著提高,当pH大于6后,改性火山岩颗粒对Cu2+和Zn2+去除率增速变缓,并伴有沉淀出现;温度的影响表明:随温度升高改性火山岩颗粒对Cu2+和Zn2+去除效率升高,分析认为该过程是吸热反应,且为自发过程;对Cu2+吸附去除,改性火山岩颗粒最佳投加为10 g/L,对Zn2+吸附去除,改性火山岩最佳投加量为6 g/L;改性火山岩颗粒对Cu2+和Zn2+吸附去除过程属于快吸附过程,饱和吸附时间为8 h。     

新型包埋污泥EPS吸附小球对含Cd2+废水吸附性能的研究

运用包埋法在吸附小球内包埋污泥胞外聚合物(EPS)制备新型吸附小球,研究新型EPS吸附小球的吸附性能,并利用扫描电镜SEM对其进行性能表征;主要考察溶液的pH、温度、EPS投加量及Cd2+的初始浓度对小球吸附性能的影响,建立小球吸附的动力学模型。结果表明,包埋了EPS的吸附小球具有更大的比表面积,对Cd2+的吸附效果更好,且该过程符合Langmuir准二级动力学吸附方程;吸附量与溶液的pH和温度有密切的关系;在Cd2+的初始质量浓度为60 mg/L的条件下,随着温度的升高,小球对Cd2+的吸附效果明显好于其他吸附反应,在包埋了EPS后,小球对Cd2+的最大吸附量由之前的45.31%提高到了64.78%。     

Cu2+和Cd2+在改性纳米碳黑和钠基膨润土上的吸附稳定性及其影响因素

通过Cu2+和Cd2+在改性纳米碳黑(MCB)和钠基膨润土(Na-B)上的吸附-解吸实验,研究了MCB和Na-B对Cu2+和Cd2+的吸附特性和吸附稳定性。研究表明:Cu2+和Cd2+在MCB和Na-B上的吸附动力学能用准二级动力学方程拟合。吸附等温线能用Freundlich方程、Langmuir方程拟合。Freundlich拟合得到的n值均大于1;Langmuir拟合得到MCB对Cu2+和Cd2+的最大吸附量分别为344mmol/kg和222.2 mmol/kg,Na-B对Cu2+和Cd2+的最大吸附量分别为59mmol/kg和45mmol/kg。用0.01mol/L的Ca Cl2对吸附了Cu2+或Cd2+的两种吸附剂进行解吸时,解吸率受p H值影响较大,受温度的影响较小。用不同浓度的Ca Cl2进行解吸时,解吸率变化不大。Cu2+在两种吸附剂上的吸附稳定性均大于Cd2+,MCB对两种重金属的吸附稳定性均大于Na-B。     

废啤酒酵母同步吸附水中Pb2+、Zn2+、Cd2+的研究

利用废啤酒酵母同步吸附处理含Pb2+、Zn2+、Cd2+废水,考察了初始pH、反应时间和初始浓度等因素对去除率的影响,并对吸附动力学进行探讨.结果表明:废啤酒酵母对Pb2+、Zn2+、Cd2+同步吸附去除率大小依次为Pb2+＞Cd2+＞Zn2+;三者之间存在竞争吸附;拟二级动力学方程相关系数R2＞0.99,对Pb2+和在低浓度条件下拟合情况更好,内扩散和液膜扩散联合控制吸附速率.     

Magnesium ferrite nanoparticles as a magnetic sorbent for the removal of Mn2+, Co2+, Ni2+ and Cu2+ from aqueous solution

The aim of this research was to prepare magnesium ferrite (MgFe₂O₄) magnetic nanoparticles and to investigate their sorption characteristics towards Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ ions in aqueous solution. MgFe₂O₄ was synthesized by glycine-nitrate combustion method and was characterized by low crystallinity with crystallite size of 8.2?nm, particle aggregates of 13–25?nm, BET surface area of 14?m²/g and pore size of 8.0?nm. Sorption properties of MgFe₂O₄ towards Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺ ions were studied using one-component model solutions and found to be dependent on metal ions concentration, contact time, pH and conditions of regeneration experiment. The highest sorption capacity of MgFe₂O₄ was detected towards Co²⁺ (2.30?mmol?g¹) and Mn²⁺ (1.56?mmol?g^?1) and the lowest towards Ni²⁺ (0.89?mmol?g^?1) and Cu²⁺ (0.46?mmol?g^?1). It was observed that sorption equilibrium occurs very quickly within 20–60?min. The pH_zpc of sorbent was calculated to be 6.58. At studied pH interval (3.0–7.0) the sorption capacity of MgFe₂O₄ was not significantly affected. Regeneration study showed that the metal loaded sorbent could be regenerated by aqueous solution of 10^?3 M MgCl₂ at pH 6.0 within 120?min of contact time. Regeneration test suggested that MgFe₂O₄ magnetic sorbent can be efficiently used at least for four adsorption-desorption cycles. The high sorption properties and kinetics of toxic metal ion sorption indicates good prospects of developed sorbent in practice for wastewater treatment.     

改性海泡石对废水中Pb2^＋、Hg2^＋、Cd2^＋1吸附性能的研究

用盐酸溶液对海泡石进行处理和在450C灼烧，制备出改性海泡石。在动态条件下，研究了改性海泡石对重金属离子Pb2^ 、Hg2^ 、Cd2^ 的吸附效果及吸附条件。同时探讨了改性海泡石对重金属离子Pb2^ 、Hg2^ 、Cd2^ 的吸附机理。合Pb2^ 、Hg2^ 、Cd2^ 的冶金废水经改性海泡石吸附后，重金属离子含量显著低于国家排放标准。     

Das redox-standardpotential von Co3+/Co2+

The standard potenial of the process Co³⁺+e=Co²⁺ has been calculated on the basis of the calorimetric determination of the thermal effect of the reaction Fe²⁺+Co³⁺=Fe³⁺+Co²⁺. The standard potential has also been estimated by extrapolating the cathode and anode tafel curves to intersection. The data available concerning the value of E^o_{Co³⁺/Co²⁺} have been thoroughly analysed, and the average value E^o from all independent methods of estimating the standard potential an acidic medium has been shown to be + 1·45. It has been found from the data on potentials of cobalt oxides in an alkali medium that the standard potential Co³⁺/Co²⁺ must be within the range 1·40–1·53 V. This value agrees with the value 1·45 V obtained in acidic media.     

The design of cyclic fixed-bed ion-exchange operations—III. Softening solutions containing Na+, Mg2+, Ca2+

The method presented in parts 1 and 2 for the design of simple cyclic ion-exchange processes in foxed beds is extended to the case where Na⁺, Mg²⁺ and Ca²⁺ are all present in the saturation solution. Two properties are established: firstly that the breakthrough curves corresponding to Ca²⁺ and Na⁺ mixtures in different proportions can be reduced to a single curve by using generalised coordinates, and secondly that Ca²⁺ and Mg²⁺ can be considered as a single ion of “hardness”. This means that the ternary mixture can be treated as a binary possessing the first property. These effects are incorporated into the cyclic material balances allowing the treatment given in parts 1 and 2 to be used.     

Synthesis of MFe2O4 (M=Mg2+, Zn2+, Mn2+) spinel ferrites and their structural,elastic and electron magnetic resonance properties

Structural, elastic and electron magnetic resonance investigations of spinel ferrites with the formula MFe₂O₄ (M = Mg²⁺, Zn²⁺, Mn²⁺) synthesized by the sol-gel auto-combustion method are reported here. XRD patterns revealed the co-existence of secondary phases along with the ferrite phase. The lattice parameter (8.301?Å, 8.366?Å and 8.434?Å) was found to be varying according to the ionic radii of cations. As determined by scanning electron microscopy (SEM), ZnFe₂O₄ has a comparatively narrow distribution of grain sizes (1.3–3.8?µm) compared to those in MnFe₂O₄ (0.8–4.3?µm) and MgFe₂O₄ (0.3–4.8?µm). The estimated values of average crystallite sizes (17.5?nm, 21.3?nm and 23.3?nm) determined from the X-ray diffraction peaks are considerably less than the average grain sizes (1.3?µm, 1.6?µm and 2.7?µm) estimated from the SEM histograms. The vibrational frequencies in FTIR spectra are in the conformity with the cubic spinel structure and their variation supports the variation of lattice parameter. Equal values of Poission's ratio (0.35) were obtained for the three systems which represent the isotropic behaviour of spinel ferrite systems. The exceptional low value of Lande's g-parameter for ZnFe₂O₄ indicates the dominance of Fe³⁺–O–Fe³⁺ superexchange interaction. Though cation redistribution is possible in the present ferrite systems, the secondary phases existed in these ferrite systems are predominantly influencing the structural, elastic and electron magnetic resonance properties.     

Gamma-Induced Absorption Bands Associated with Tl+, Pb2+, or Bi3+ in Potassium Borate Glasses

Gamma irradiation of potassium borate glasses containing about 1.8 mole % Tl⁺, Pb²⁺, or Bi³⁺ resulted in two induced absorption bands which the authors call T and L bands. The T band was observed at about 1.1, 1.55, or 1.8 ev, and the L band was observed at about 1.8, 2.6, or 2.7 ev in alkali borate glasses containing Tl⁺, Pb²⁺, or Bi³⁺, respectively. The shifting of the band positions to higher energies was attributed to the increasing polarizing power of these ions as in the case of the F band induced in alkali halides. The effect of the addition of cerium on the intensity of the T and L bands induced in glasses containing lead or thallium and prepared under different melting conditions suggested strongly that these two bands are associated with electron trap centers near these ions.     

Color tunable Ba3Lu(PO4)3:Tb3+,Mn2+ phosphor via Tb3+→Mn2+ energy transfer for white LEDs

Series of UV excited Ba₃Lu(PO₄)₃:Tb³⁺,Mn²⁺ phosphors with tunable green to red emissions had been prepared using solid state reactions. Powder X-ray diffraction and Rietveld structure refinement were used to investigate the phase purity and crystal structure of the prepared samples. Under UV excitation, the Ba₃Lu(PO₄)₃:Tb³⁺,Mn²⁺ samples exhibited not only the typical Tb³⁺ emission peaks but also the broad emission band of Mn²⁺ ions due to the efficient Tb³⁺→Mn²⁺ energy transfer which had been verified by luminescence spectra and decay curves. Utilizing the Inokuti-Hirayama model, the Tb³⁺→Mn²⁺ energy transfer mechanism was determined to be the electronic dipole–quadrupole interaction. Moreover, the emission spectra of Ba₃Lu(PO₄)₃:0.80Tb³⁺,0.015Mn²⁺ sample at different temperatures manifested that our prepared phosphors possessed good thermal stability. The luminescence properties investigation results revealed the potential value of Ba₃Lu(PO₄)₃F:Tb³⁺,Mn²⁺ in application for UV excited phosphor converted white light emitting diodes.     

Lattice Parameters, Ionic Conductivities, and Solubility Limits in Fluorite-Structure MO2 Oxide [M = Hf4+, Zr4+, Ce4+, Th4+, U4+] Solid Solutions

Changes in the lattice parameters of fluorite type MO₂ oxides (M = Hf⁴⁺, Zr⁴⁺, Ce⁴⁺, Th⁴⁺, U⁴⁺) due to the formation of solid solutions can be predicted by proposed empirical equations. The equations show the generalized relationship between dopant size and ionic conductivity in the binary systems of these oxides, illustrating that the smaller the difference between the dopant ionic radius and the critical dopant radius, the higher the conductivity. The solubility limit of the same periodic group elements in fluorite-structure MO₂ oxides decreaes linearly with the square of Vegard's slope for each solute as determined from the proposed equations.     

亚超细Y2O2S:Er3+,Yb3+荧光粉的制备及其上转换发光特性

采用高温固相法,通过引入添加剂Bi2O3制备了亚超细(约为500 nm)的上转换荧光粉Y2O2S:Er3+,Yb3+.采用X射线衍射、扫描电子显微镜、能谱、吸收光谱和荧光光谱研究了Bi2O3掺杂对Y2O2S:Er3+,Yb3+荧光粉晶体生长和和上转换发光特性的影响(在980 nm和1550nm波长下激发).结果表明:加入Bi2O3添加剂,由于低温烧结过程中产生液相影响晶体生长,制备出亚超细荧光粉.该荧光粉在980 nm和1550nm波长激发下发光强度有所降低,但仍产生较强上转换发光.     

Diffusion of Co2+ and Ni2+ in Magnesium Oxide

Rates of diffusion of Co²⁺ and Ni²⁺ ions in the MgO lattice were determined by a micrographic method. The energies of activation for the transport process were 65 and 36 kcal per mole, respectively. The penetration curve in these systems exhibited a plateau followed by a sudden decrease in concentratior.