离子液体改性沸石吸附水溶液中Cr(VI)的研究

利用离子液体十六烷基-3-甲基咪唑氯化物对天然沸石进行表面改性,并将改性沸石用于水中Cr(VI)的吸附,研究离子液体浓度、反应时间、p H等条件对Cr(VI)吸附性能的影响,采用X射线衍射和红外光谱对离子液体改性沸石进行表征。结果表明,咪唑离子浓度不大于0.3 mol/L的低浓度离子液体改性的沸石对Cr(VI)的吸附作用不明显,咪唑离子浓度大于0.9 mol/L的离子液体改性的沸石对Cr(VI)具有好的吸附效果;酸性条件有利于改性沸石对Cr(VI)的吸附;咪唑离子浓度为0.6、0.9 mol/L的离子液体改性的沸石吸附Cr(VI)平衡的时间分别为240、8 min。     

氨水改性活性炭纤维吸附苯乙烯的性能

主要研究采用氨水对活性炭纤维ACF表面进行改性,制备了3种不同的改性ACF,测定ACF孔结构和表面酸碱基团,并测定了苯乙烯在改性ACF床层的吸附透过曲线,讨论了改性ACF的孔结构和表面酸碱基团对其吸附性能的影响.结果表明,与原始ACF相比,经氨水改性后的活性炭纤维ACF其表面碱性基团含量、孔容及其比表面积增加,从而明显提高了对苯乙烯的吸附容量;用浓度为6mol/L的氨水改性的ACF2其微孔孔容及其比表面积最大,其对苯乙烯的吸附容量也最大.     

天然斜发沸石的改性及其对海水中K~+吸附交换容量的研究

为提高天然斜发沸石对海水中K+的吸附交换容量,对天然沸石进行了电炉、微波和超声波加热物理改性以及微波化学改性研究。重点考察了不同微波功率和处理时间时盐改性以及不同微波化学改性条件下所得沸石对海水中K+的吸附交换容量,同时对不同改性沸石的晶体结构进行了XRD表征。结果表明,天然斜发沸石经微波盐改性后对海水中K+的吸附交换容量有所提高,并随微波处理功率的增加和时间的延长而增大;经微波化学改性后吸附交换容量显著提高,可达0.71mmol/g;各种改性方式未对沸石的结构构成破坏,所得改性沸石的晶体结构基本相似。     

NaCl-MnO2联合改性沸石对水中Zn2+的动态吸附

研究了NaCl-MnO₂改性沸石填料柱对水中Zn²⁺的动态吸附性能。探讨了填料厚度、Zn²⁺的初始质量浓度和流速对穿透曲线的影响。结果表明,NaCl-MnO₂改性沸石能有效去除水中的Zn²,填料层增厚,穿透曲线上的穿透点向右移动,穿透时间延长;而流速、Zn²⁺的初始浓度增大,穿透曲线上的穿透点向左移动,穿透时间缩短;用Thomas模型描述Zn²⁺初始质量浓度为50mg/L、滤速为4mL/min时改性沸石对Zn²⁺的吸附动力学,相关系数为0.9994,平衡吸附容量为12.04mg/g。     

含环氧基团三元共聚物纳米纤维的植酸改性

以含环氧基团三元共聚物纳米纤维为载体,用植酸(PA)为改性剂,得到表面含有磷酸根基团的功能性纤维膜。研究了植酸浓度、反应温度、反应时间对纤维膜改性的影响。采用傅里叶变换红外光谱、热失重分析、扫描电镜、光学接触角测量仪,对纤维膜的结构与表面润湿性进行表征。结果表明,当植酸浓度20%,反应温度70℃,反应时间3h时,改性得到的功能化纤维膜的铅离子吸附容量为60mg/g;改性后纤维膜的形态仍能保持微纳米级网状结构,其直径约为408nm,静态接触角为39.12°,呈现了良好的亲水性能。     

β-萘酚改性活性炭及其对钴吸附性能的研究

采用β-萘酚改性制备选择性吸附钴的活性炭材料,SEM和FTIR表征测试发现,活性炭改性中受到溶胀作用,颗粒变粗大和疏松,表面结构中官能团和基团增多。并研究了β-萘酚浓度、改性时间、改性温度等改性条件对钴吸附性能的影响。同时探讨了改性活性炭吸附时间、温度、剂量等条件对吸附效率的影响,通过对等温吸附模型进行拟合,研究改性活性炭吸附钴的行为。结果表明,β-萘酚改性活性炭对钴吸附的优化工艺为氢氧化钠溶解β-萘酚后与亚硝酸钠按1∶1摩尔比混合配制α-亚硝基-β-萘酚溶液,浓度为1 mol/L、改性时间1.5h、温度95~100℃、吸附时间1h、吸附温度25℃、溶液中性条件下,钴吸附率达到99%以上,钴吸附平衡浓度下降到1mg/L以下,最大吸附容量为25.52mg/g。吸附等温线符合Langmuir等温线模型,拟合系数为0.99995,表明改性活性炭对钴的吸附模式是以单层吸附为主。     

羟基磷灰石表面吸附性能的研究综述

羟基磷灰石(HA)吸附能力受酸碱度、其它离子浓度等外界因素的影响,对HA表面改性处理能在一定程度上改变HA表面电性结构,从而改善吸附性能.动力学上多因素作用影响HA吸附速度或改变具体的吸附行为.通过总结HA对无机物、金属及有机物的作用条件、反应过程及吸附机理发现:人们还没有找到一个普遍的理论模型来解释HA与其它材料发生吸附作用的过程,目前对HA表面吸附性能的研究还停留在具体零碎材料的相互作用上.在HA表面嫁接有用的作用基团或物质,通过改变HA表面部分结构以改善吸附性能成为目前和今后一段时间内HA吸附性能研究的重点之一.     

高比表面积SiO_2为基质的含N复合分离材料的制备及其吸附性能

制备了PEI/SiO2复合分离材料,用红外光谱鉴定了其-N基团的存在,用SEM观察了其表面结构,并且用树脂吸附铜离子量来表征了其结合PEI的量.结果表明,复合分离材料对于铜离子的吸附速率很快,在0.5～0.7h就已经达到了饱和,静态最大吸附容量为47.1mg/g树脂;同时树脂具有再生性能,经过10次的解吸-吸附试验后,其吸附容量降至42.5mg/g树脂.     

沸石的改性及其除锌效果研究

为改善天然沸石对水中Zn(Ⅱ)的去除效果,采用NaCl、MnO2、NaCl-MnC2对沸石进行改性,并分别详细研究了MnO2制备中各主要因素及NaCl改性液浓度、改性质量体积比等对改性沸石去除Zn(Ⅱ)效果的影响.结果表明,MnO2改性的最佳条件是沸石与KMnO4和MnSO4溶液凝胶化反应30min,陈化2.5d,沸石质量/(沸石质量+理论生成MnOh质量)为0.6、灼烧温度为400℃,NaCl改性的最佳条件是NaCl改性液浓度为1mol/L、沸石质量/NaCl溶液体积为0.04g/L、改性温度为75℃.在最佳MnO2和NaCl改性条件下对沸石进行NaCl-MnO2联合改性,改性后的沸石用于处理Zn2+初始浓度为50mg/L的水样,其对Zn2+的去除率高于NaCl改性沸石和MnO2改性沸石.     

纳米氧化石墨烯复合材料的制备及重金属废水处理研究

以改进的Hummers法制备了纳米氧化石墨烯(GO),以乙二胺四乙酸(EDTA)为改性剂，制备了功能化GO复合材料。通过XRD、SEM、FT-IR对功能化GO复合材料的晶格结构、微观形貌和官能团进行了表征，并以此作为吸附剂，测试了不同pH值、初始浓度、吸附时间等吸附环境对含Cd的重金属废水吸附性能的影响。结果表明，EDTA表面具有丰富的羟基、羧基等含氧基团，嫁接到GO表面后使GO表面的活性点位增多，Cd(Ⅱ)被功能化GO复合材料表面的活性点位所吸附后沉积在了原有的沟槽中，使复合材料的表面变得光滑。当pH=6时，功能化GO复合材料对含Cd重金属废水的吸附容量和去除率达到最大值，分别为45.8 mg/g和95.3%;在初始浓度为120 mg/L时，吸附容量和去除率达到了最大值，分别为66.5 mg/g和96.3%;在吸附时间为60 min时，可达饱和吸附，吸附容量和去除率达到最高值，分别为78.0 mg/g和98.5%。经过5次重复使用后，吸附容量可保持在23.8 mg/g,去除率保持在85.4%,具有优异的循环性能。     

改性沸石对电镀废水中Pb2+、Zn2+、Ni2+的吸附

将天然沸石进行处理制备出多孔质改性沸石颗粒。在静态条件下，研究了改性沸石颗粒对重金属离子Pb^2 ,Zn^2 ,Ni^2 的吸附效果及条件，含Pb^2 ,Zn^2 ,Ni^2 的电镀废水经改性沸石颗粒吸附后，废水中Pb^2 ,Zn^2 ,Ni^2 的含量低于国家排放标准。     

Studies on sorption properties of zeolite derived from Indian fly ash

Indian fly ash has been completely converted to crystalline porous 13X zeolite by NaOH fusion at 600 degrees C followed by hydrothermal treatment at 105 degrees C for 20 h. Obtained materials were characterized by XRD, SEM and surface area measurement. Prepared material was used for the sorption study of different metal ions (Cu(2+), Co(2+) and Ni(2+)) at different pH, temperature. Thermodynamic data (DeltaS, DeltaH and DeltaG) corresponding to different metal ion uptake were evaluated from Langmuir equation. In all the experiment sorption capacity of prepared zeolite was found to be quite high than that of fly ash at acidic pH. However, the uptake selectivity order for both the materials is Cu(2+)>Co(2+)>Ni(2+).     

The use of natural Kazakhstan zeolites for the development of gas purification catalysts

The results of investigation of catalysts based on natural zeolite in comparison with synthetic ZSM-5 zeolite used in reduction of nitrogen oxides and conversion of carbon monoxide are presented. It was found that rearrangement of the crystal structure of natural zeolite begins upon heating it above 500 °C in air. The structure of natural zeolite has been improved by introduction of various modifiers and selection of thermal regime of samples training. It has been shown that developed compositions of press-mass for preparation of carriers for gas purification catalysts in the form of granules and tablets satisfy the requirements on ductility and mechanical strength. The efficiency of synthesized granular and block Cu–Ce, Cu–Ni–Cr, Ti–V, Ti–VW, and TiO₂–V₂O₅ catalysts based on natural and synthetic zeolites was determined in conversion of CO and nitrogen oxides. The results of X-ray structure analysis of clinoptilolite of the Republic of Kazakhstan deposits—Chankanai and Taizhuzgen—are represented in comparison with synthetic ZSM-5 zeolite. The paper also comprises data about their thermal stability, ductility, and strength of compositions on their base. Metals particles morphology and dispersity are studied by the method of electronic microscopy. These particles were used as active components of synthesized catalysts.     

Arsenic removal from groundwater by MnO2-modified natural clinoptilolite zeolite: effects of pH and initial feed concentration

Adsorption of arsenic (As(5+)) on natural and MnO(2)-modified clinoptilolite-Ca zeolite adsorbents was investigated to explore the feasibility of removing arsenic from groundwater using natural zeolite adsorbents. The natural and MnO(2)-modified clinoptilolite-Ca zeolite adsorbents were characterized with nitrogen adsorption at 77K for pore textural properties, scanning electron microscopy with energy dispersive X-ray spectroscopy and X-ray fluorescence for morphology, elemental composition and distribution. Batch adsorption equilibrium experiments were conducted to study the effects of pH and initial feed concentration on arsenic removal efficiency. It was found that the amphoteric properties and arsenic removal efficiency of the natural clinoptilolite-Ca zeolite were significantly improved after modification with MnO(2). The MnO(2)-modified zeolite could effectively remove arsenic from water at a wide pH range, and the arsenic removal efficiency that is basically independent of the pH of feed solutions varies slightly with the initial arsenic concentration in the feed solutions. The removal efficiency obtained on the modified zeolite was doubled as compared to that obtained on the unmodified zeolite. The MnO(2)-modified clinoptilolite-Ca zeolite appears to be a promising adsorbent for removing trace arsenic amounts from water.     

Synthesis,characterization, and electrochemical properties of Ni(OH)<Subscript>2</Subscript>/ultra-stable Y zeolite composite

A novel composite of Ni(OH)₂/ultra-stable Y zeolite materials was synthesized by an improved chemical precipitation method, which used the ultra-stable Y zeolite as the template. The Ni(OH)₂/ultra-stable Y zeolite composite and its microstructure were characterized by X-ray diffraction measurements and transmission electron microscopy. Electrochemical studies were carried out using cyclic voltammetry, chronopotentiometry technology and ac impedance spectroscopy, respectively. The result shows that the loose-packed whisker Ni(OH)₂ phase has profound impacts on electrode performance at very high power output. A maximum discharge capacity of 185.6 mA-h/g (1670 F/g), or 371 mA-h/g (3340 F/g) after correcting for weight percent of nickel hydroxide phase at the current density of 625 mA/g could be achieved in a half-cell setup configuration for the Ni(OH)₂/ultra-stable Y zeolite electrode, suggesting its potential application in electrode material for secondary batteries and electrochemical capacitors. Furthermore, the effect of NH₄Cl concentration on the electrochemical properties characteristics has also been systemically explored.     

丙烯酸钠-玉米芯接枝共聚物的制备及其对Ni2+的吸附机制

为探索利用农业废弃物玉米芯制备高效吸附材料去除水溶液中重金属离子的可行性.利用原子转移自由基聚合(ATRP)技术将大量对重金属离子具有较强亲和能力的羧基嫁接到玉米芯表面,制备出丙烯酸钠-玉米芯接枝共聚物(MC-g-PGMA-g-PAA-Na),同时采用热重、FTIR、SEM、EDS和XPS对吸附Ni2+前后的吸附材料进...     

Destabilization of emulsions by natural minerals

This study developed a novel method to destabilize emulsions and recycle oils, particularly for emulsified wastewater treatment. Natural minerals were used as demulsifying agents, two kinds of emulsions collected from medical and steel industry were treated. The addition of natural minerals, including artificial zeolite, natural zeolite, diatomite, bentonite and natural soil, could effectively destabilize both emulsions at pH 1 and 60 °C. Over 90% of chemical oxygen demand (COD) can be removed after treatment. Medical emulsion can be even destabilized by artificial zeolite at ambient temperature. The mechanism for emulsion destabilization by minerals was suggested as the decreased electrostatic repulsion at low pH, the enhanced gathering of oil microdroplets at elevated temperature, and the further decreased surface potential by the addition of minerals. Both flocculation and coalescence were enhanced by the addition of minerals at low pH and elevated temperature.     

Removal of mixed heavy metal ions in wastewater by zeolite 4A and residual products from recycled coal fly ash

The removal performance and the selectivity sequence of mixed metal ions (Co(2+), Cr(3+), Cu(2+), Zn(2+) and Ni(2+)) in aqueous solution were investigated by adsorption process on pure and chamfered-edge zeolite 4A prepared from coal fly ash (CFA), commercial grade zeolite 4A and the residual products recycled from CFA. The pure zeolite 4A (prepared from CFA) was synthesized under a novel temperature step-change method with reduced synthesis time. Batch method was employed to study the influential parameters such as initial metal ions concentration, adsorbent dose, contact time and initial pH of the solution on the adsorption process. The experimental data were well fitted by the pseudo-second-order kinetics model (for Co(2+), Cr(3+), Cu(2+) and Zn(2+) ions) and the pseudo-first-order kinetics model (for Ni(2+) ions). The equilibrium data were well fitted by the Langmuir model and showed the affinity order: Cu(2+) > Cr(3+) > Zn(2+) > Co(2+) > Ni(2+) (CFA prepared and commercial grade zeolite 4A). The adsorption process was found to be pH and concentration dependent. The sorption rate and sorption capacity of metal ions could be significantly improved by increasing pH value. The removal mechanism of metal ions was by adsorption and ion exchange processes. Compared to commercial grade zeolite 4A, the CFA prepared adsorbents could be alternative materials for the treatment of wastewater.     

The effect of interfacial interactions on the mechanical properties of polypropylene/natural zeolite composites

The effect of interfacial interactions on the mechanical properties of polypropylene (PP)/natural zeolite composites was investigated under dry and wet conditions. Interfacial interactions were modified to improve filler compatibility and mechanical properties of the composites by surface treatment of natural zeolite with a non-ionic surface modifier; 3 wt% polyethylene glycol (PEG) and three different types of silane coupling agents; 3-aminopropyltriethoxysilane (AMPTES), methyltriethoxysilane (MTES) and 3-mercaptopropyltrimethoxysilane (MPTMS), at four different concentrations (0.5–2 wt%). PP composites containing (2–6 wt%) zeolite were prepared by an extrusion technique. The tensile properties of the composites determined as a function of the filler loading and the concentration of the coupling agents were found to vary with surface treatment of zeolite. Silane treatment indicated significant improvements in the mechanical properties of the composites. According to the dry and wet tensile test results, the maximum improvement in the mechanical properties was obtained for the PP composites containing 1 wt% AMPTES treated zeolite. The improvement in the interfacial interaction was confirmed using a semi-empirical equation developed by Pukanszky. Good agreement was obtained between experimental data and the Pukanszky model prediction. Scanning electron microscopy studies also revealed better dispersion of silane treated filler particles in the PP matrix.     

Characterization and reactivity of sulfided NiNaY zeolite catalysts for thiophene conversion

The hydrodesulfurization (HDS) of thiophene has been studied in the presence of hydrogen at 613 K in a fixed-bed flow reactor over a series of sulfided Ni-exchanged Y zeolite catalysts. Both oxidic precursors and sulfided catalysts have been characterized by X-ray photoelectron spectroscopy, infrared spectroscopy of NO and pyridine adsorbed probes, and acidity measurements. Sulfidation led to the formation of sulfided Ni²⁺ and, probably, reduced Ni, species that migrated to the external surface layers and to supercages of the zeolite. There is also an important increase of Brönsted acidity. Both HDS (major reaction) and cracking activities increased with increasing Ni content and, therefore, with increasing acidity of the zeolites, and decreased markedly with pyridine poisoning. Precalcination at 873 K or nonsulfidation pretreatments of the Ni-exchanged zeolites led to an important decrease of HDS activity. All the results point out that sulfided Ni-species formed on zeolite are predominantly involved in the HDS of thiophene.