乙二胺四乙酸插层水滑石吸附Cd(Ⅱ)的影响因素研究

采用共沉淀的方法合成了镁铝水滑石和EDTA插层水滑石,并对两者进行表征分析,同时比较分析了EDTA插层水滑石和镁铝水滑石对Cd2+的吸附效果及影响因素,确定了合成高吸附容量的EDTA插层水滑石的最佳条件和其吸附镉的最佳吸附条件。结果表明:p H值为12、晶化时间为1 h和水浴温度为50℃是插层水滑石最佳合成条件;吸附剂投加量为1.0 g/L、时间为50 min、p H值为6、温度为50℃是插层水滑石吸附Cd2+的最佳条件。     

乙二胺四乙酸插层水滑石吸附Cd(Ⅱ)的吸附特征研究

采用共沉淀方法合成了EDTA插层水滑石,在吸附剂投加量1.0 g/L、时间50 min、p H值6、温度50℃为插层水滑石吸附Cd2+的最佳条件下,分析了EDTA插层水滑石的解吸再生性能,进行了吸附动力学和吸附热力学研究,初步分析了EDTA插层水滑石吸附溶液中Cd2+的吸附机理。结果表明,硝酸溶液对吸附饱和的插层水滑石的解吸率较高;EDTA插层水滑石对溶液中Cd2+的吸附规律能更好的符合准二级动力学模型和Langmuir等温方程模型,该吸附为自发的、吸热的化学吸附且其对溶液中Cd2+的吸附主要是表面吸附机制和螯合机制的综合作用。     

氨法脱硫工艺高氯吸收液净化研究

针对氨法脱硫工艺运行过程中,吸收液中Cl -不断富集,造成吸收效果降低,设备腐蚀加剧情况,采用水滑石工艺对高氯吸收液进行了脱氯研究。为保证氯离子脱除效果,采用钙盐沉淀法先将吸收液中的硫酸根脱除。在两种不同的水滑石工艺对比中,与合成水滑石相比,直接加入水滑石效果较好。在焙烧温度400 ℃,吸附1 h,水滑石与吸收液质量比为0.3时,氯离子脱除效果最好。     

水滑石类材料的合成及其在污染控制中的应用

水滑石类材料具有独特的性能,作为催化及吸附材料应用广泛.本文就水滑石类材料的合成现状进行了概述,并就水滑石类材料的碱性,阳离子的可搭配性,层间阴离子的可交换性等几个方面以及在污染控制中应用进行论述.     

磁性焙烧态锌铝类水滑石吸附腐殖酸与再生

采用化学共沉淀一步法制备了磁性锌铝类水滑石(M·Zn/Al LDHs),并经煅烧得到磁性焙烧态锌铝类水滑石(M·Zn/Al LDO),用以吸附去除水中腐殖酸。文章探讨了M·Zn/Al LDO去除腐殖酸的影响因素,研究了M·Zn/Al LDO吸附腐殖酸的动力学与热力学,考察了吸附腐殖酸后M·Zn/Al LDO焙烧再生的条件。结果表明,当M·Zn/Al LDO投加量0.2 g/L时腐殖酸去除率随着投加量的增大而增大,腐殖酸的初始浓度增大时吸附量增大但去除率减小。在pH 4～8腐殖酸去除率较高,保持在97%以上。NO_3~-和F~-对去除腐殖酸的影响甚微,而H_2PO_4~-则影响较大。拟二级动力学模型与Langmuir吸附等温线较好地描述吸附过程,吸附过程以物理吸附为主,化学吸附为辅。吸附腐殖酸后的M·Zn/Al LDO通过煅烧恢复焙烧态锌铝类水滑石结构,腐殖酸分解,再生效果良好,且磁性未被破坏。可见,磁性焙烧态锌铝类水滑石是一种高效且有潜在应用前景的去除腐殖酸的水处理材料。     

焙烧态镁铝水滑石处理阴离子染料废水研究

采用传统过饱和双滴法合成出Mg/Al为3的碳酸根型水滑石(LDH),经500℃高温煅烧制备出焙烧产物(CLDH),用x-射线、红外光谱和电镜对它们进行了表征。分别考察了焙烧温度、反应时间、pH、投加量、反应温度和初始浓度等因素对焙烧态水滑石吸附酸性铬蓝K模拟废水效果的影响。结果表明,对于100mg/L的铬蓝K溶液,500℃焙烧态水滑石,投加量为0.06g,在pH=3.5左右,室温下反应1h,去除率最高可达98%以上。四次回收重复利用的CLDH对铬蓝K的去除率仍为90%以上,CLDH是一种良好的环保吸附材料。     

实时合成水滑石分离模拟放射性核素锶的研究

采用实时合成水滑石的方法从高放废液中分离模拟放射性核素锶,通过单因素实验并借助XRD分析确定了最佳分离实验条件,同时,运用FTIR、SEM等技术手段对合成的含锶水滑石的结构、形貌进行了分析.结果表明,当Sr2+初始浓度为70mg.L-1、pH值为10.5、n(Mg+Sr)/n(Al)为3时,锶的去除率最高可达95%以上;XRD和SEM分析结果表明,锶嵌入了水滑石的晶格中,合成的含锶水滑石形貌为层状六边形;含锶水滑石煅烧产物主要为尖晶石,且煅烧产物中未见氧化锶,表明嵌入到水滑石晶格中的锶在煅烧后存在于尖晶石的晶体结构中.     

水滑石类材料在水污染治理中的应用研究

水滑石及其焙烧形态的应用涉及多个学科领域,在环境治理中主要作为催化剂和吸附剂(离子交换剂)加以应用。水滑石材料具有层间离子交换性能和记忆效应两大特性,使得水滑石类材料可以作为高效阴离子吸收剂(或有效载体)而应用于水污染环境治理领域。此外,本文还对于改性水滑石类化合物的环境应用作了初步评述。     

插层水滑石的组装及对对硝基甲苯的吸附

采取一步改性、离子交换和焙烧复原3种方法实现阴离子表面活性剂十二烷基硫酸钠(SDS)插层Mg3Al-NO3-水滑石(HT)的组装,通过XRD、FT-IR、TEM、TOC、NMR等表征手段对插层水滑石(SDS-HT)进行表征.研究了SDS-HT吸附对硝基甲苯的性能及影响因素,探讨了其吸附机理,并定量描述了分配作用和表面吸附对总吸附量的相对贡献.结果表明,3种插层方法均制备了层状结构良好的阴离子黏土,其中焙烧复原法制备的样品SDS含量最多. SDS在SDS-HT中形成了增溶(分配)作用较强的有机相,并影响表面吸附作用和分配作用在吸附过程中的贡献率.3种样品对对硝基甲苯均有良好的吸附作用,在本研究浓度范围内,对硝基甲苯的吸附主要由表面吸附作用提供,焙烧复原法所得样品平衡浓度为162mg/L时的吸附量最大,为44.5mg/g.     

CuAl水滑石衍生物吸附Cr(Ⅵ)的性能研究

采用共沉淀法制备了CuAl-HTLs水滑石及其衍生物材料CuAl-LDOs,研究了CuAl-LDOs材料对Cr(Ⅵ)吸附反应动力学,并考察了pH值、反应温度对吸附容量的影响,通过对样品XRD和FT-IR表征分析了CuAl-LDOs对Cr(Ⅵ)的吸附过程;结果表明,CuAl-LDOs材料Cr(Ⅵ)吸附动力学曲线符合Elovich方程,其饱和吸附量达178.24mg/g;溶液的pH是影响吸附容量的重要因素,当pH=6时,样品对Cr(Ⅵ)的吸附性能最好;温度会影响吸附和脱附反应的平衡,当温度为40℃时,样品吸附性能最好。通过对CuAl-HTLs水滑石、衍生物材料CuAl-LDOs和CuAl-HTLs水滑石吸附Cr6+后烘干再生的材料CuAl-Reg的XRD和FT-IR分析发现,CuAl-LDOs对Cr(Ⅵ)的吸附本质上属化学吸附,对阴离子的吸附机制是通过结构重建来实现的,由于记忆效应CuAl-LDOs在吸附阴离子后可以恢复形成层状水滑石结构。     

Adsorption removal of thiocyanate from aqueous solution by calcined hydrotalcite

A hydrotalcite with Mg/AI molar ratio 2 was prepared by co-precipitation method and was characterized by XRD, TG/DTA, Zeta potential and BET surface area. The hydrotalcite was calcined at 500℃, with the dehydration from interlayer, the dehydroxilation from the brucite-like layer and the decomposition of carbonate successively, transformed into the mixed oxide type. The removal of thiocyanate from aqueous solution by using the original hydrotalcite and calcined hydrotalcite （HTC-500） was investigated. The results showed that the thiocyanate adsorption capacity of calcined hydrotalcite was much higher than that of the original form. Calcined hydrotalcite was particularly effective at removing thiocyanate, and that the effective range of pH for the thiocyanate removal are between 5.5-10.0. The experimental data of thiocyanate removal fit nicely with Langmuir isotherm, and the saturated adsorption uptake was 96.2 mg SCN-/g HTC-500. The adsorption of thiocyanate by calcined hydrotalcite follows first-order kinetics. And the intercalation to the structure recovery for calcined hydrotalcite. But the presence of additional anions could affect the adsorption behavior of thiocyanate.     

应用水滑石实时合成分离模拟核素钕

应用水滑石实时合成的方法从高放废液中分离模拟放射性核素钕,通过酸碱滴定、单因素试验及X-射线衍射(XRD)研究确定了最佳分离条件,用红外光谱(FT-IR)、扫描电镜(SEM)、透射电镜(TEM)等对合成的含钕水滑石的结构、形貌进行了分析. 结果表明:模拟放射性核素钕的最佳分离条件,初始ρ(Nd3+)为150 mg/L,pH为10,n(Mg)/［n(Al)+n(Nd)］为3,在该条件下5次平行试验钕的去除率平均值为96.40%,并且钕嵌入到了水滑石的晶格中,合成的含钕水滑石形貌大多为层状六边形;含钕水滑石煅烧产物主要为尖晶石,煅烧产物中未见氧化钕相,表明嵌入到水滑石晶格中的钕在煅烧后仍存在于尖晶石的晶体结构中.      

Ethyl thiosemicarbazide intercalated organophilic calcined hydrotalcite as a potential sorbent for the removal of uranium(VI) and thorium(IV) ions from aqueous solutions

This work was conducted to determine the practicability of using a new adsorbent 4-ethyl thiosemicarbazide intercalated,organophilic calcined hydrotalcite(ETSC-OHTC) for the removal of uranium(U(VI)),and thorium(Th(IV)) from water and wastewater.The FTIR analysis helped in realizing the involvement of nitrogen and sulphur atoms of ETSC in binding the metal ions through complex formation.Parameters like adsorbent dosage,solution pH,initial metal ions concentration,contact time and ionic strength,that influence adsorption phenomenon,were studied.The optimum pH for maximum adsorption of U(VI) and Th(IV) was found to be in the range 4.0-6.0.The contact time required for reaching equilibrium was 4 hr.The pseudo second-order kinetic model was the best fit to represent the kinetic data.Analysis of the equilibrium adsorption data using Langmuir,Freundlich and Sips models showed that the Freundlich model was well suited to describe the metal ions adsorption.The K F values were 25.43 and 29.11mg/g for U(VI) and Th(IV),respectively,at 30°C.The adsorbent can be regenerated effectively from U(VI) and Th(IV) loaded ones using 0.01mol/L HCl.The new adsorbent was quite stable for many cycles,without much reduction in its adsorption capacity towards the metals.     

水溶液中磷的吸附与预测模型

用红壤和水滑石作为吸附剂,进行了水溶液中磷的等温吸附试验,目的是研究吸附剂(W)0效应和起始吸附质浓度(C)0效应对经典方程参数变异的影响,分析经典Langmuir和Freundlich方程在液/固离子吸附体系中的适用性和验证新吸附模型的预测精确度。试验结果显示,红壤和水滑石在吸附磷的过程中存在明显的吸附剂和吸附质浓度效应,单一的经典方程仅适用于给定吸附剂或吸附质浓度的体系,因此,用其参数来表征不同吸附剂的吸附能力或描述不同吸附剂或吸附质浓度水平上的吸附规律具有一定的局限性。数据分析表明,单位吸附剂的平衡吸附量qe不唯一由初始浓度C0或液相平衡浓度Ce所决定,而是C0/W0或Ce/W0的函数,新吸附预测模型能较好的反映红壤和水滑石磷吸附的总体趋势。新的预测模型用来描述红壤和水滑石的磷吸附曲线时具有较高的精确度。在实践中,新模型可用来预测给定条件下磷的吸附量和所需吸附剂的用量。     

Mg/Al金属氧化物的物化性质及吸附特性

为研究微波煅烧和常规煅烧下的Mg/Al金属氧化物的物化性质、吸附特性及机理,通过XRD(X射线衍射)、SEM(扫描电镜)、BET-BJH(比表面积-孔结构)和pH_ZPC(零电荷点)等表征手段分析了微波煅烧对水滑石结构、形貌、纹理性质及表面电荷性质的影响.结果表明:微波煅烧可获得结晶度更高、片状结构更规整的Mg/Al金属氧化物;微波煅烧使Mg/Al金属氧化物的比表面积由184 m2/g增至205 m2/g,孔容和孔径分别由0.245 cm3/g和2.15 nm增至0.263 cm3/g和2.19 nm;pH_ZPC由12.3增至12.6.微波煅烧和常规煅烧下的Mg/Al金属氧化物的对Cr(Ⅵ)吸附的ΔH(标准焓变)分别为42.86和41.23 kJ/mol,E_a(吸附活化能)分别为21.82和22.59 kJ/mol,二者的吸附过程均为化学吸附且受扩散控制,在该研究条件下的二者理论吸附量最大值分别为93.51和90.31 mg/g,微波煅烧提升了Mg/Al金属氧化物吸附能力,但并不显著;微波煅烧使得Mg/Al金属氧化物更易发生结构还原,其对Cr(Ⅵ)的吸附实质就是结构还原过程.研究显示,微波煅烧并没有改变Mg/Al金属氧化物吸附特性和机理.      

Preparation and utilization of wheat straw anionic sorbent for the removal of nitrate from aqueous solution

In order to reduce the impact of eutrophication caused by agricultural residues(i.e.,excess nitrate)in aqueous solution,economic and effective anionic sorbents are required.In this article,we prepared anionic sorbent using wheat straw.Its structural characteristics and adsorption properties for nitrate removal from aqueous solution were investigated.The results indicate that the yield of the prepared anionic sorbent,the total exchange capacity,and the maximum adsorption capacity were 350%,2.57 mEq/g,and 2.08 mmol/g, respectively.The Freundlich isotherm mode is more suitable than the Langmuir mode and the adsorption process accords with the first order reaction kinetic rate equation.When multiple anions(SO_4~(2-),H_2PO_4~-,NO_3~-,and NO_2~-)were present,the isotherm mode of prepared anionic sorbent for nitrate was consistent with Freundlich mode;however,the capacity of nitrate adsorption was reduced by 50%.In alkaline solutions,about 90% of adsorbed nitrate ions could be desorbed from prepared anionic sorbent.The results of this study confirmed that the wheat straw anionic sorbent can be used as an excellent nitrate sorbent that removes nitrate from aqueous solutions.     

Preparation1 and utilization of wheat straw anionic sorbent for the removal of nitrate from aqueous solution

In order to reduce the impact of eutrophication caused by agricultural residues (i.e. excess nitrate) in aqueous solution, economic and effective anionic sorbents are required. In this article, we prepared anionic sorbent using wheat straw. Its structural characteristics and adsorption properties for nitrate removal from aqueous solution were investigated. The results indicate that the yield of the prepared anionic sorbent, the total exchange capacity, and the maximum adsorption capacity were 350%, 2.57 mEq/g, and 2.08 mmol/g, respectively. The Freundlich isotherm mode is more suitable than the Langmuir mode and the adsorption process accords with the first order reaction kinetic rate equation. When multiple anions (SO42-, H2PO4-, NO3-, and NO2-) were present, the isotherm mode of prepared anionic sorbent for nitrate was consistent with Freundlich mode; however, the capacity of nitrate adsorption was reduced by 50%. In alkaline solutions, about 90% of adsorbed nitrate ions could be desorbed from prepared anionic sorbent. The results of this study confirmed that the wheat straw anionic sorbent can be used as an excellent nitrate sorbent that removes nitrate from aqueous solutions.