Mg/Al双金属氧化物吸附Cr(Ⅵ)的动力学和热力学机理

通过静态吸附实验,研究了Cr(Ⅵ).Mg/Al水滑石焙烧产物层状双金属氧化物(layered double oxides,LDO)的吸附性能.考察了温度对其吸 附性能的影响,探讨了吸附动力学和热力学规律.研究表明:吸附动力学符合准二级动力学模型,LDO的吸附活化能为21.42kJ/mol,表现为扩散控 制过程.在293~333 K温度范围内,吸附自由能(△Go)变小是Cr(Ⅵ)ELDO上的吸附推动力;吸附热(吸附焓变H)为5.12 kJ/mol,是自发的物理吸附过程;LDO吸附Cr(Ⅵ)为熵增过程.其熵变为49.12 J/(mol·K).结合XRD表征结果探讨了吸附机理:LDO吸附Cr(Ⅵ)无配位摹交换、化学键等强的作用力,Mg/Al金属氧化物在吸附Cr(Ⅵ)后恢复为LDH层状结构,因此,LDO对Cr(Ⅵ)的强吸附能力是冈为其具有较强的结构"记忆效应".     

阴离子交换树脂吸附柠檬酸中的硫酸根离子

采用动态法研究阴离子交换树脂吸附柠檬酸(CA)中硫酸根离子,通过分析溶液相和树脂相中柠檬酸与SO24-的变化趋势,确立了阴离子离交树脂上柠檬酸与硫酸根离子的交换机理。研究表明,强碱性阴离子交换树脂中吸附的CA-不能被柠檬酸液中SO24-置换出;反之,弱碱性离子交换树脂所吸附的CA-可被柠檬酸液中SO24-置换出,且功能基团为树脂吸附柠檬酸液中硫酸根离子的重要因素。     

纳米金属氧化物去除水体重金属的研究进展

简要介绍了用于吸附水体重金属的几种纳米金属氧化物,包括:纳米铁氧化物、纳米锰氧化物、纳米铝氧化物、纳米钛氧化物、纳米锌氧化物、纳米镁氧化物、纳米铈氧化物以及纳米金属氧化物复合材料,讨论了各种纳米金属氧化物处理水体重金属的优缺点,并展望了其应用前景。     

共存硫酸根对聚吡咯改性赤泥从水体中吸附除磷的影响

研究用聚吡咯改性赤泥从共存硫酸根的水体中吸附除磷,考察了硫酸根摩尔浓度、吸附时间及水体pH等因素对除磷效果的影响,并对达到吸附平衡后的聚吡咯改性赤泥进行吸附动力学分析、磷酸盐形态分析、无定形铁/铝含量测定和FTIR分析,探究了硫酸根对聚吡咯改性赤泥吸附除磷的影响机制。结果表明,在水体pH为3～10的范围内,一定浓度的硫酸根能够提升聚吡咯改性赤泥对磷酸盐的吸附去除能力,使去除率保持在93%以上。聚吡咯改性赤泥中结晶态铁活化为无定形态,是硫酸根共存条件下吸附促进效果产生的主要原因。研究成果对聚吡咯改性赤泥的进一步优化具有一定理论指导意义。     

金属氧化物及其氢氧化物去除水体中磷的研究进展

含磷污水排放造成水体富营养化是我国水污染的重要原因。为去除水体中的磷,吸附法由于其效率高、成本低等优势倍受青睐。目前常用的除磷吸附剂主要有天然及合成的金属氧化物或氢氧化物及其与多孔载体结合的复合吸附剂。本文综述了近十年来,金属氧化物或金属氢氧化物吸附剂在水体磷吸附方面所取的研究进展,指出目前存在问题,分析水体磷吸附研究的方向,助于我国水体富营养化控制。     

Mg-Ni复合金属氧化物对染料吸附性能的研究

本文我们用廉价易得的硝酸镁、硝酸镍为原料采用简单的湿化学的方法用苯甲醇作为结构导向剂成功的合成Mg-Ni复合金属氧化物。并采用TEM、XRD、等技术对产物进行了表征。以活性艳红X3B为吸附对象,研究了Mg-Ni不同比例的复合金属氧化物吸附剂的吸附性能。同时比较了氧化镍(111)、氧化镁(111)对活性艳红X3B染料的吸附性能。     

活性炭/碳纳米管复合电极电吸附机理研究

按活性炭∶碳纳米管∶PVDF=7.2∶0.8∶2质量比制备活性炭/碳纳米管复合电极,并对其构成的EST模块进行吸附动力学、等温吸附和电迁移拟合研究,分析其吸附机理。结果表明,准一级反应动力学模型和Langmuir模型能够很好的拟合、描述活性炭/碳纳米管复合电极在EST脱盐过程中的吸附机理,说明电吸附速率只与一种反应物的浓度有关且是单离子层吸附,EST吸附过程中离子的电迁移率随迁移时间的变化趋势可以用指数形式的方程很好的拟合。     

活性炭/碳纳米管复合电极电吸附机理研究

按活性炭∶碳纳米管∶PVDF=7.2∶0.8∶2质量比制备活性炭/碳纳米管复合电极,并对其构成的EST模块进行吸附动力学、等温吸附和电迁移拟合研究,分析其吸附机理。结果表明,准一级反应动力学模型和Langmuir模型能够很好的拟合、描述活性炭/碳纳米管复合电极在EST脱盐过程中的吸附机理,说明电吸附速率只与一种反应物的浓度有关且是单离子层吸附,EST吸附过程中离子的电迁移率随迁移时间的变化趋势可以用指数形式的方程很好的拟合。     

复合金属氧化物吸附水中十二烷基苯磺酸钠的试验研究

研究了复合金属氧化物（LDO）对模拟废水中十二烷基苯磺酸钠（SDBS）的吸附行为,考察了pH值、温度、吸附时间等因素对SDBS去除的影响,并对吸附后的产物进行了碳酸钠解析试验研究。结果表明：当pH=7,温度为25℃,吸附时间为30min,LDO投加量为0．1g／100mL,SDBS初始浓度为700mg／L时,SDBS的去除率高达95．33％。产物经焙烧再生后重复吸附4次,产物对SDBS的去除率仍可达90．07％,实现了废物的再利用。     

微塑料对水体中重金属吸附机理的研究

污染物中微塑料是一种新型的、分布十分广泛的颗粒物。对于微塑料已经有一部分学者研究确定其可以吸附污染物,但是对于微塑料在重金属方面的吸附作用相关研究尚少。通过从动力学以及热力学对聚苯乙烯吸附性进行分析:其吸附与二级动力学模型相符和Langumuir为单层吸附,吸附特性为化学吸附,温度变化会对反映造成正向影响。     

钛酸盐纳米材料去除水中重金属离子的研究进展

去除水中的重金属离子使受污染的水体得以修复是一项紧迫和具有挑战性的课题。钛酸盐纳米材料具有比表面积大、离子交换性能强、合成简易、价格低廉、原料来源广泛等优点,作为重金属离子的新型吸附材料,具有良好的吸附效果。综述了钛酸盐纳米材料去除水中重金属离子的研究与最近进展,系统地介绍了重金属离子的吸附效果、吸附机理和影响因素,总结了为降低成本、提高吸附容量而采取的解吸、再生、修饰手段,对该材料未来应用前景进行了展望。     

淀粉/二氧化硅微球对水中重金属离子的吸附性能

利用土豆淀粉、玉米淀粉、正硅酸乙酯为原料,氨水为催化剂,通过溶胶-凝胶法制备了淀粉/二氧化硅复合微球,研究了该复合微球对水中铅离子的吸附性能。结果表明,在弱碱性条件下,淀粉/二氧化硅复合微球对水中铅离子表现出良好的吸附性能,其对铅离子的吸附行为符合Langmuir模型和Freundlich模型,对铅离子的饱和吸附量为31.34 mg/g。动力学研究表明,淀粉/二氧化硅复合微球对铅离子的吸附符合拟二级动力学模型,在淀粉/二氧化硅复合微球的活性点上的化学反应为吸附控制步骤。     

棉花模板Zn/Ti/Fe-LDO吸附水中硝酸盐机制

通过共沉淀-焙烧法制备以棉花为模板的Zn/Ti/Fe焙烧态类水滑石（YLDO）和无棉花模板的Zn/Ti/Fe焙烧态类水滑石（NLDO）,运用SEM、N₂吸附法、FTIR和XRD对其进行表征,考察YLDO和NLDO对水中硝酸盐的吸附机制及其紫外光催化再生的机理。结果表明,YLDO在形态中引入棉花的遗迹,比表面积增大为74.8 m²·g^-1,大孔数量增加;在化学成分上引入了C元素,提高了吸附性能;形成磁性物质,可通过磁性分离回收。pH为7、298 K时,YLDO对水中硝酸盐的最大吸附量为66.57 mg·g^-1,比NLDO增加了22.6%。YLDO和NLDO吸附硝酸盐的吸附等温线符合Langmuir方程,吸附动力学可用准二级动力学方程来描述,吸附热力学研究表明吸附过程为自发吸热过程。吸附饱和的YLDO和NLDO可在紫外光照射下再生,5次再生循环后仍保持较高的吸附性能。YLDO可通过吸附-磁分离-紫外光催化再生工艺有效去除水中硝酸盐,不产生二次污染,在硝酸盐废水处理中具有潜在的应用前景。     

Comparison of NO adsorbing ability and process on Pt/Mg/Al oxide catalysts prepared by different methods

Pt/Mg/Al metal oxide catalysts were prepared by impregnation and co-precipitation methods, respectively. These samples were characterized by BET, XRD and NO-TPD; their NO _X storage property and adsorbing intermediate species were investigated with NSC and FTIR. The results showed that the prepared methods exert significant influence on the physical structure properties and the adsorption abilities of NO. (Pt)/Mg/Al samples prepared by impregnation (IM) have larger specific areas and higher NO _X storage capacity than (Pt)/Mg/Al catalysts prepared by co-precipitation (CP). The intermediate species of NO adsorbing process indicated that NO was firstly adsorbed as bridged nitrites both on Pt/Mg/Al (IM) and on Pt/Mg/Al (CP), then on Pt/Mg/Al (IM) the nitrites transferred into monodentate and bidentate nitrate species while on Pt/Mg/Al (CP) the nitrites only transferred into monodentate nitrate species.     

Selectivity and competitive mechanism of cation exchange resin for Fe,Mg, and Al ions in phosphoric acid

The presence of iron, magnesium, and aluminum elements as the primary impurities in wet-process phosphoric acid (WPA) adversely affects the industrial phosphoric acid and subsequent phosphorus chemical products. This study aims to investigate the selectivity and competition mechanism of Sinco-430 cation exchange resin for Fe, Mg, and Al ions in phosphoric acid solution. By studying the effects of different process conditions on the removal efficiency, the suitable conditions for the static removal of metal ions from Fe-Mg, Al-Mg, and Fe-Al binary systems were determined: solid–liquid mass ratio (S/L) of 0.3, phosphoric acid concentration of 27.61 wt.%, system temperature of 50°C, and rotational speeds of 200, 400, and 200 rpm, respectively. By calculating the selectivity coefficients of the resin for metal ions under different experimental conditions and mutual replacement experiments, the semi-empirical formulas for the selectivity coefficients were derived and order of selectivity was determined as follows: Mg²⁺ > Fe²⁺ > Al³⁺. Visual MINTEQ 3.1 software and density functional theory (DFT) calculations demonstrated that at low pH, the main forms of Fe, Mg, and Al present in phosphoric acid were FeH₂PO₄⁺, Mg²⁺, and AlH₂PO₄²⁺, respectively. This finding explained the differences in selectivity of the resin for Fe, Mg, and Al. The dynamic removal of metal ions from phosphoric acid was investigated. The order of metal ion selectivity of the resin by the dynamic method is the same as that of the static method, and the dynamic exchange behaviour was most consistent with the Yan model.     

Effect of chitosan addition to BTCA/CA processed cotton fabrics for adsorbing metallic ions from waste water

One of the most important properties of chitosan, a derivative of chitin, is that it is able to chelate with certain heavy metal ions, and this property can be applied to process waste water containing heavy metal ions. In this research, using BTCA/CA as a crosslinking reagent with chitosan added, cotton fabrics were cured and allowed to undergo an adsorption reaction in CuSO₄ and ZnSO₄ solutions. The effect of different curing temperatures and time, as well as different adsorptive temperatures and time, were studied. The cotton processed fabrics were analyzed by Fourier transform infrared analysis (FTIR), scanning electronic microscope (SEM), and thermal gravity analysis (TGA) to study the crosslinking reaction with the cotton‐processed fabrics. The results indicate: (1) the BTCA/CA‐processed cotton fabrics with an addition of chitosan have a better adsorptive capacity than the processed fabrics without chitosan; (2) the crosslinked fabrics are better in adsorbing copper ions as chitosan concentration, curing temperature and time, and adsorptive temperature and time increase; (3) the adsorption rate of copper and zinc ions are linearly proportional to the changes of time, so that the slope shows that the adsorption rate of crosslinked fabrics for copper ions is faster than for zinc ions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3264–3269, 2006     

水凝胶吸附法去除水中重金属离子研究综述

水凝胶是一种具有三维网络结构的高分子材料,因其具有吸附性能强、环境友好、可具备特定功能等诸多优点而倍受环保研究人员的青睐。近年来水凝胶作为一种新型重金属吸附材料在水处理领域中得到了特别的重视,并取得了显著进展。对壳聚糖类、丙烯酰胺类、天然高分子接枝类三类代表性水凝胶的制备及吸附处理重金属废水的研究成果进行了较系统的梳理和总结,并对目前国内外的研究进展进行了分析和讨论,进一步指出了今后的研究重点和方向。     

花生壳改性处理含铅废水及吸附机理研究

通过对花生壳改性处理模拟含铅废水,增强对铅离子的吸附能力,结果表明,最佳改性方法是花生壳在0.015 mol/L高锰酸钾中搅拌改性4 h。改性前后花生壳的IR图谱发现吸附位点种类没有增加,但是数量明显增加;BET比表面积测试结果表明,改性后花生壳的比表面积增加了78%。在初始条件为50 m L含Pb2+100 mg/L模拟含铅废水时,最佳的吸附条件为0.2 g改性花生壳在含铅废水中吸附2 h,Pb2+除去率为99.48%,较未改性的花生壳提高了42.63%。吸附机理研究表明,采用Lagergren准二级动力学模型和Langmuir等温吸附模型可以准确描述吸附行为,拟合实验数据平衡吸附量为24.93 mg/g,与实验结果一致。     

花生壳改性处理含铅废水及吸附机理研究

通过对花生壳改性处理模拟含铅废水,增强对铅离子的吸附能力,结果表明,最佳改性方法是花生壳在0.015 mol/L高锰酸钾中搅拌改性4 h。改性前后花生壳的IR图谱发现吸附位点种类没有增加,但是数量明显增加;BET比表面积测试结果表明,改性后花生壳的比表面积增加了78%。在初始条件为50 m L含Pb2+100 mg/L模拟含铅废水时,最佳的吸附条件为0.2 g改性花生壳在含铅废水中吸附2 h,Pb2+除去率为99.48%,较未改性的花生壳提高了42.63%。吸附机理研究表明,采用Lagergren准二级动力学模型和Langmuir等温吸附模型可以准确描述吸附行为,拟合实验数据平衡吸附量为24.93 mg/g,与实验结果一致。     

Effects of chitosan addition to DMEU‐processed cotton fabrics for adsorbing metallic ions in waste water

This study examines the effects of adding chitosan to the curing treatment of cotton fabrics, using dimethylolethyleneurea as a crosslinking reagent; in particular, how the adsorption of the processed cotton fabrics for metallic ions is influenced. Different concentrations of added chitosan, different curing temperatures and time, as well as different adsorption times and temperatures were examined. The cotton fabrics studied were compared with other adsorptive materials, and also, were examined by Fourier Transform Infrared Analysis (FTIR), Scanning Electronic Microscope (SEM), and Thermal Gravity Analysis (TGA) to study the crosslinkage reaction. The experimental results were as follows: the adsorption of copper and zinc ions increases as chitosan concentration increases, with the best adsorption when chitosan concentration is 0.5%; the adsorption of copper and zinc ions increases as the curing temperature rises, with the best adsorption at 140°C; the adsorption increases with longer curing time, with the best adsorption at 6 min after the processing begins. For adsorption of zinc ions, the cotton fabrics containing chitosan have better adsorption than pure chitosan, but worse adsorption than activated carbon. For the adsorption of copper ions, chitosan is the best, processed cotton fabrics are the second, and activated carbon is the poorest. The adsorption of these two kinds of ions increases with the longer time and higher temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4440–4445, 2006