水滑石除磷的吸附动力学研究

采用共沉淀法制备了Mg/Al水滑石,研究了不同Mg/Al物质的量比、材料用量、不同pH条件下Mg/Al水滑石吸附除磷的动力学特征,从而对吸附速率的控制过程进行分析。结果表明水滑石对磷的吸附能较好地符合准二级动力学方程、Elovich动力学方程和内扩散模型。n(Mg)/n(Al)=3是水滑石最理想配比,水滑石投加量越大,外扩散过程越慢;一定范围内pH的升高能促进水滑石对磷吸附速率和吸附容量的提升。     

纳米水滑石结构表征及其对氯离子吸附性能

以天然菱镁矿为原料,采用尿素法制备纳米Mg-Zn-Al水滑石、Zn-Mg-Al-Fe水滑石,用XRD、SEM对水滑石的结构特征、晶粒尺寸进行表征,并利用水滑石的层间阴离子交换性及结构“记忆效应”,来研究焙烧态水滑石对溶液中氯离子的吸附性能.结果表明:Zn-Mg-Al水滑石的结晶度比Mg-Al水滑石、Zn-Mg-Al-Fe水滑石的高,同时Zn-Mg-Al水滑石的粒径非常均匀,尺寸在20 nm左右,为层片状结构,而且其晶体形貌呈现花瓣状结构;在Mg-Al水滑石中,随着n(Mg)∶n(Al)的增加,溶液中Cl-的去除率逐渐提高,且在n(Mg)∶n(Al) =4时去除率最大,为85.96％;当n(M2+)∶n(M3+)固定为2时,Zn-Mg-Al水滑石对Cl-的去除率要比Mg-Al水滑石对Cl-的去除率高13.25％,但Zn-Mg-Al-Fe水滑石对Cl-的去除率却比Mg-Al水滑石低32.53％.     

纳米水滑石的结构表征及其对氯离子的吸附性能

以天然菱镁矿为原料,采用尿素法制备纳米Mg-Zn-Al水滑石(LDH)、Zn-Mg-Al-Fe水滑石,采用XRD、SEM、N2吸附-脱附对水滑石的结构特征、晶粒尺寸进行表征,并利用水滑石的层间阴离子交换性及结构"记忆效应",来研究焙烧态水滑石(CLDH)对溶液中氯离子的吸附性能。结果表明:Zn-Mg-Al-LDH结晶度比Mg-Al-LDH、Zn-Mg-Al-Fe-LDH高,同时Zn-Mg-Al-LDH的粒径非常均匀,尺寸在20nm左右,为层片状结构,而且其晶体结构呈现花瓣状结构;在Mg-Al-CLDH中,随着n(Mg/Al)的增加,溶液中Cl~-的去除率逐渐提高,且在n(Mg/Al)=4时去除率最大,为85.96%;当n(M~(2+)/M~(3+))固定为2时,Zn-Mg-Al-CLDH对Cl~-的去除率要比Mg-Al-CLDH对Cl~-的去除率高13.25%,但Zn-Mg-Al-Fe-CLDH的去除率却比Mg-Al-CLDH低32.53%;焙烧态水滑石n(Zn/Mg/Al)=1∶1∶1时,有较大的比表面积837.183m~2/g,较大的孔容为0.496cc/g,其相应吸附能力也较大。     

瓜环对部分腐殖酸模型物去除的规律研究

根据腐殖酸的结构特点选取适当模型物,采取紫外-可见分光技术研究瓜环的投加量、时间、温度及pH值对腐殖酸模型物去除的规律。研究表明,模型物的结构是影响瓜环对腐殖酸模型物去除的最主要因素,其中羧基和芳环是影响瓜环对模型物吸附效果的主要基团;瓜环对腐殖酸及其模型物的吸附主要为物理吸附,并且吸附有较宽的pH值范围;瓜环对腐殖酸模型物去除作用的较优条件为瓜环投加量1.8g/L,初始浓度20mg/L,平衡时间5h。在此条件下,瓜环对腐殖酸模型物苯甲酸、2-萘酚、萘、苯甲醚及腐殖酸的去除率分别为94.52%、98.24%、81.52%、85.66%和99.85%。     

多羟基醇类共溶剂对Mg/Al水滑石水热制备的影响

以Mg（NO3）2.6H2O为镁源、Al（NO3）3.9H2O为铝源,采用水热法制备Mg/Al水滑石。鉴于水滑石中广泛存在的氢键相互作用,以多羟基醇为共溶剂,对比分析了水、水/乙醇、水/乙二醇、水/丙三醇及水/季戊四醇等5种溶剂条件下水热合成得到的Mg/Al水滑石的结构和热性质。利用XRD、SEM、IR、DSC等的分析结果表明,随着共溶剂中醇羟基数目的增多,所得水滑石中结晶水的水合程度提高。共溶剂与水滑石之间水滑石,晶粒形貌类似于纯水得到的水滑石。而以水/丙三醇及水/季戊四醇为溶剂得到的水滑石,晶形变的不规则,且伴随着粒径尺寸变小和晶粒团聚现象。同时,随着共溶剂中醇羟基数目的增多,层间结合水的释放温度提高,而层间CO2脱除和基本层上的羟基脱水温度则相应降低。     

镁铝铜水滑石的合成、表征及性能研究

采用共沉淀法合成了不同摩尔投料(Mg/Al/Cu)的碳酸根型水滑石，用X-射线、红外光谱、热重．差热分析对水滑石进行了表征，测定对NOx的吸附性能。结果表明，Mg/Al/Cu摩尔比为2．5：1：0．5，2：1：1，1：1：2时合成的复合氧化物中都具有“feitknecht”结构。热重-差热分析结果显示合成样品的分解均有两个过程，掺入铜量少，热稳定性高。Mg/Al/Cu为2．5：1：0．5的水滑石对氮氧化物的吸附容量为1484．4mg/g。     

酒石酸柱撑水滑石吸附水中的Ni~(2+)的特性研究

采用离子交换法制得酒石酸插层MgAl水滑石(MgAl-TA LDHs),并进行了XRD、IR、SEM、比表面积及孔径分析表征。考察了MgAl-TA LDHs吸附剂对溶液中Ni 2+的吸附能力,探讨了水滑石吸附剂投加量、Ni 2+溶液浓度、pH值以及吸附温度对Ni 2+吸附率的影响,并进行了动力学和热力学特征的研究。结果表明,适宜的水滑石投加量为2g/L,pH值以中性为宜,对于Ni 2+浓度不超过100 mg/L的溶液室温下Ni 2+吸附率在60%以上,而高温有利于提高Ni 2+吸附率。吸附过程符合二级动力学模型,吸附等温曲线可用R-P模型来描述。吸附过程能够自发进行,为吸热过程,属于化学吸附。     

NiMgAl类水滑石制备条件研究

采用共沉淀法合成了不同摩尔投料比的NiMgAl类水滑石化合物.测定了Ni、Mg、Al单盐以及不同摩尔比的混合硝酸盐溶液的滴定曲线,考察了加料方式、晶化温度、晶化时间、原料配比对类水滑石合成的影响.通过XRD、IR对合成物进行表征,结果表明,在恒定pH值为8～9,n(Mg Ni)/n(Al)=1～3,n(Mg)/n(Ni)=8～16,晶化温度为65℃,晶化时间6h的条件下即得到晶相单=的NiMgAl-HTLcs;随n(Mg Ni)/n(Al)的增加,类水滑石结构的规整性提高,n(Mg)/n(Ni)比增加,层间距略有减小.     

环境因子对磁性瓜环去除腐殖酸的影响及其稳定性研究

采用紫外可见分光技术研究了磁性瓜环(MQ[n])对水体污染物腐殖酸(HA)的去除性能、稳定性及磁性能。考察了MQ[n]的投加量、HA的初始浓度、溶液温度、作用时间及pH值等因素对去除HA的影响。结果表明,MQ[n]对HA具有很好的去除作用,其中,MQ[n]投加量与pH值对HA的去除效果影响较大。其较优条件为MQ[n]投加量20mg、HA初始质量浓度10 mg/L、吸附温度315 K、平衡时间360 min、pH值7.0,在此条件下,MQ[n]对HA的去除率达到98.73%。MQ[n]稳定性好,且易于磁性分离。     

环境因子对磁性瓜环去除腐殖酸的影响及其稳定性研究

采用紫外可见分光技术研究了磁性瓜环(MQ[n])对水体污染物腐殖酸(HA)的去除性能、稳定性及磁性能。考察了MQ[n]的投加量、HA的初始浓度、溶液温度、作用时间及pH值等因素对去除HA的影响。结果表明,MQ[n]对HA具有很好的去除作用,其中,MQ[n]投加量与pH值对HA的去除效果影响较大。其较优条件为MQ[n]投加量20mg、HA初始质量浓度10 mg/L、吸附温度315 K、平衡时间360 min、pH值7.0,在此条件下,MQ[n]对HA的去除率达到98.73%。MQ[n]稳定性好,且易于磁性分离。     

MgAl-LDH吸附甲基橙性能研究

在水热反应温度为180℃,反应溶液pH值=9～10,反应时间为4h,反应总物质浓度为0.1mol/L的实验条件下,探索Mg/Al的摩尔比对MgAl-LDH吸附甲基橙性能的影响,并考察了材料再生后的吸附性能。研究结果表明,Mg/Al摩尔比为2.5∶1时的MgAl-LDH吸附甲基橙性能最优;在最佳吸附条件下,MgAl-LDH对甲基橙吸附量高达83.33mg/g;并对吸附材料循环利用焙烧温度进行探讨,可再生循环焙烧温度在400℃达到最佳,循环使用3次吸附性能保持良好。此外,对Mg/Al-LDH及其各个温度焙烧产物进行TG-DTA和SEM表征,显示其片状构型及对甲基橙进行的离子交换吸附和表面静电吸附作用。     

凹凸棒石黏土-腐植酸复合吸附剂吸附Cr(Ⅵ)的性能研究

为促进凹凸棒石黏土-腐植酸复合吸附剂在水处理中的应用,用酸改性的甘肃靖远凹凸棒石黏土和天祝褐煤提取的腐植酸制备出凹凸棒石黏土-腐植酸复合吸附剂,通过SEM、XRD、FT-IR等分析方法对复合吸附剂的结构进行了表征,考察了物料配比及吸附时间、pH值、温度、投加量和初始浓度对Cr(Ⅵ)吸附率的影响。结果表明:靖远凹凸棒石黏土最佳酸改性条件为盐酸5 mol/L,酸化时间120 min,酸用量固液比为1∶10。当Cr(Ⅵ)的起始浓度为0.1 g/L,体积为50 m L,复合吸附剂用量为1.2 g,吸附时间为6 h,p H值为6,温度25℃,酸改性的凹凸棒石黏土与腐植酸的最佳复合比为1∶3时,复合吸附剂对Cr(Ⅵ)的吸附率达到91.7%。复合吸附剂对Cr(Ⅵ)的吸附满足Freundlich模型。在25~45℃条件下,吸附过程ΔG <0、ΔS=87.46 J/(mol·K)、ΔH=-21.2 kJ/mol,表明该吸附是一个自发、熵增、放热的过程。     

Preparation and characterization of hydrotalcite-like materials from flyash for transesterification

In the present study, attempts were made to synthesize Mg–Al hydrotalcite-like materials with bifunctional properties from flyash and flyash-based zeolite by coprecipitation method. The synthesized hydrotalcite and their corresponding Mg–Al mixed oxides obtained after calcination were characterized for their structural, compositional, thermal, and morphological properties. The synthesized hydrotalcite had Mg/Al ranging from 1.3 to 2.3. The activity of the synthesized catalyst was estimated in transesterification of mustard oil, and the effects of reaction time, catalyst concentration, and methanol-to-oil molar ratio on biodiesel production were also investigated. A maximum yield of 93.4 % was obtained with methanol-to-oil molar ratio of 12:1, 7 wt% catalyst concentration for 6 h of reaction at 65 °C. The average value of activation energy of biodiesel in the conversion range of 0.2 < X < 0.9 was 130.5 kJ mol^?1. This study showed the potential application of flyash and its use in modified Mg–Al hydrotalcite materials as heterogeneous catalysts in biodiesel production.     

纳米晶镁铝水滑石制备机理及抗毒性研究

以尿素为沉淀剂制备纳米晶镁铝水滑石,考察不同镁铝比制备的纳米晶镁铝水滑石催化剂对大豆油酯交换的影响以及催化剂的抗水抗酸性和使用寿命,并探讨纳米晶镁铝水滑石的合成机理.随镁铝摩尔比增加,酯交换反应所需时间减少,当m(Mg2 ):m(Al3 )=3:1时,转化率高达94.2%;当m(Mg2 ):m(Al3 )=4:1时,使用寿命最长,可重复使用5次.纳米晶镁铝水滑石具有较强抗水抗酸性,故在进行酯交换反应中无须脱水脱酸.     

The influence of ferric iron in calcined nano-Mg/Al hydrotalcite on adsorption of Cr (VI) from aqueous solution

The influence of ferric iron in calcined nano-Mg/Al hydrotalcite on removal of Cr (VI) from aqueous solution was studied from aspects of structure characteristics, adsorption properties and mechanism discussions. The calcined hydrotalcites (CH-Mg/Al and CH-Mg/Al/Fe) were obtained by thermal decomposition of their corresponding precursors and characterized by XRD, TEM, pH(PZC) and FTIR. The adsorption properties were studied as a function of pH, initial Cr (VI) concentration and contact time. The results showed that the nature of adsorption is endothermic and spontaneous for both CH-Mg/Al and CH-Mg/Al/Fe, but the thermodynamic parameter value changes revealed the addition of Fe(3+) is disadvantage to adsorption process and the theoretical saturated adsorption capacity decreased by approximately 10.2mg/g at tested temperatures. The removal mechanism involved not only intercalation but adsorption on external surface of the layers and interlayer anion exchange for both CH-Mg/Al and CH-Mg/Al/Fe. Furthermore, the results also indicated that intercalation accounts for a large proportion during removal process whatever for CH-Mg/Al, or for CH-Mg/Al/Fe. Additionally, the replacement of Al(3+) by Fe(3+) in CH-Mg/Al led to the interlayer anion exchange more difficult. On the basis of the results, it is concluded that the existence of ferric iron in calcined Mg/Al hydrotalcite is unfavorable to removal of Cr (VI) from aqueous solution.     

Al(Ⅲ)改性胶原蛋白絮凝材料的结构表征及对废弃钻井液絮凝的研究

利用鞣制化学中铝鞣机理,将Al(Ⅲ)络合在明胶水解得到的胶原蛋白分子上,制备Al(Ⅲ)改性胶原蛋白絮凝材料,利用XRD、荧光光谱和XPS对产物结构及作用机理进行表征与分析。将所制备的絮凝剂用于油田废弃钻井液的絮凝,以其CODCr去除率和悬浮物含量为指标,考察了絮凝条件对废弃钻井液处理效果的影响。结果表明胶原蛋白分子与Al(Ⅲ)间发生了配位反应,制备出了Al(Ⅲ)改性胶原蛋白絮凝剂。其用于废弃钻井液絮凝时,用量为20.7g/L,pH值为6～9,温度为20～40℃。絮凝后,废弃钻井液CODCr去除率达80.1%,悬浮物含量从初始的2115mg/L降至190mg/L,絮凝效果明显。     

Use of an integrated photocatalysis/hollow fiber microfiltration system for the removal of trichloroethylene in water

This work focused on the degradation of toxic organic compounds such as trichloroethylene (TCE) in water, using a combined photocatalysis/microfiltration (MF) system. The performances of the hybrid system were investigated in terms of the removal efficiency of TCE and membrane permeability, in the presence or absence of background species, such as alkalinity and humic acids. The mass balancing of the fate of TCE during photocatalytic reactions was performed in order to evaluate the feasibility of the photocatalytic membrane reactor (PMR). Greater TCE degradation (>60%) was achieved with an increase in the TiO2 dosage (up to 1.5g/L) in PMR, but a substantially large TiO2 dosage brought about a decrease in TCE degradation efficiency. The photocatalytic decomposition of TCE appeared to be more effective in acidic pH conditions than with a neutral or alkaline pH. The addition of alkalinity and humic acid into the feedwater did not have a significant effect on TCE degradation, while humic acids (whose dose was 1mg/L as TOC) in the feedwater played a part in a decline of permeability by 60%. Membrane permeability in the PMR was also affected by tangential velocities. An improvement of 60% in flux was achieved when the tangential velocity increased from 0.19 to 1.45m/s. This is because flow regimes can govern the deposition of TiO2 particles on the membrane surface.     

蒙脱土/Fe3O4/腐殖酸复合材料对U(Ⅵ)的作用机制

通过水热法制备蒙脱土/Fe₃O₄/腐殖酸复合材料(MFH),探究pH值、MFH的投加量、吸附时间、U(Ⅵ)初始浓度及温度等因素对MFH吸附U(Ⅵ)的影响。结果表明:在所选实验条件范围内,MFH的投加量对其吸附U(Ⅵ)的影响最大;当U(Ⅵ)初始浓度为5 mg·L^-1,pH值为6,MFH投加量为0.3 g·L^-1,温度为30℃时,MFH对U(Ⅵ)去除在30 min后达到平衡,此时去除率达到97.7%;MFH对U(Ⅵ)的吸附符合准二级动力学模型和Langmuir模型;MFH对U(Ⅵ)的去除机理为络合作用和还原作用。再生实验表明,经5次吸附-解吸后,MFH复合材料对U(Ⅵ)的吸附率仍在90%以上,表明MFH对U(Ⅵ)的去除效果较好且具有高效重复利用性。     

钙钛矿型La0.9Sr0.1NiO3催化剂的合成条件及其可见光催化活性的研究

采用溶胶-凝胶法制备了钙钛矿型La0.9Sr0.1NiO3复合氧化物光催化剂,通过TG-DTA、XRD、可见光催化性能等对合成产物的热分解过程、物相结构和可见光催化活性进行了研究;采用单因素实验探究了合成工艺条件(柠檬酸用量、pH值、煅烧温度、煅烧时间)对合成产物的物相结构和可见光催化性能的影响。结果表明,在柠檬酸用量与金属离子的总量比为1∶1,pH=1.5,400℃预处理4h,700℃煅烧4h时可制备出单一相的六方晶系的La0.9-Sr0.1NiO3晶体;在500 W氙灯的照射下,当La0.9Sr0.1NiO3催化剂用量为1.20g/500mL时,在180min内对13.2mg/L的甲基橙溶液的脱色率达到62.1%。     

纳米镁铝水滑石的制备及其对聚氨酯阻燃性能的影响

采用液相沉淀法制备纳米镁铝水滑石微粉,利用XRD、TEM和TG对试样进行表征,研究了反应温度、干燥时间以及碳酸根浓度对镁铝水滑石纳米晶的影响.镁铝水滑石微粉经硅烷偶联剂KH550表面改性后填充到聚醚多元醇组合料中,采用原位聚合法制备出镁铝水滑石/软质聚氨酯纳米复合材料,研究了纳米镁铝水滑石对聚氨酯的阻燃效果及阻燃机理,并与Al(OH)_3阻燃效果进行对比.实验结果表明,晶粒尺寸随反应温度的升高而增大;干燥5h镁铝水滑石的热分解性能较好;适当提高碳酸根浓度可以改善镁铝水滑石晶体规整度;硅烷偶联剂KH550用量为5%时对镁铝水滑石表面改性效果最好;镁铝水滑石阻燃剂填充软质聚氨酯复合体系的阻燃效果要优于Al(OH)_3阻燃剂.