Adsorption Characterization of Strontium on PAN/Zeolite Composite Adsorbent

This work reports the adsorption of strontium from aqueous solutions onto PAN/zeolite composite. The strontium adsorption on the composite adsorbent was studied as a function of initial strontium concentration, pH of the solution, contact time and temperature. Adsorption isotherms like Langmuir, Freundlich,Dubinin–Radushkevich (D–R) and Temkin were used to analyze the equilibrium data at the different concentrations.Adsorption process well fitted to Temkin isotherm model. Thermodynamic parameters such as the changes in enthalpy, entropy and Gibbs’ free energy were determined, showing adsorption to be an exothermic and spontaneous process.

Removal of lead from aqueous solutions by condensed tannin gel adsorbent

Lead has caused serious environmental pollution due to its toxicity, accumulation in food chains and persistence in nature. In this paper, lead removal from aqueous solutions was investigated using condensed tannin gel adsorbent synthesized from a natural tannin compound. It is found that the adsorption is strongly affected by pH values of aqueous solutions. Within pH range of 3 5—6, when initial lead concentration is 100 mg/L, removal efficiency is more than 90%. Adsorption equilibrium is reached within 150 minutes. The adsorption isotherm fits well with the Langmuir equation, by which the saturated adsorption uptake of 190 mg Pb 2+ /g dry tannin gel adsorbent is obtained. By means of thermodynamics analysis, it is revealed that the process is exothermic and the adsorption heat is up to 38 4 kJ/mol. With respect to high efficiency, moderate pH requirement and minimized second pollution, the tannin gel adsorbent exhibits a promising potential in the removal of lead from wastewater.

A WATER-COMPATIBLE PHENOLIC HYDROXYL MODIFIED POLYSTYRENE AS AN ADSORBENT FOR ADSORBING PHENOLIC COMPOUNDS FROM AQUEOUS SOLUTIONS

A water-compatible phenolic hydroxyl modified polystyrene adsorbent (AM-1) for adsorbing and removing phenolic compounds from aqueous solutions was prepared by covalent bonding of phenolic hydroxyl groups to the surface of porous polystyrene-divinylbenzene beads, this resin can be used directly without wetting process. A comparison of the sorption properties of the new resin and Amberlite XAD-4 toward four phenolic compounds, phenol, p-cresol, p-chlorophenol, and p-nitrophenol was made. The capacities of equilibrium adsorption of AM-1 for all four phenolic compounds increased around 20% over that of Amberlite XAD-4, which may be contributed to phenol hydroxyl group on the surface and the unusual pore distribution. At their dilute solution, the equilibrium adsorption capacities of AM-1 for phenol increased about 62% over that of Amberlite XAD-4, while equilibrium adsorption capacities of the other three phenolic compounds increased 4-35%, suggesting an advantage of AM-1 over Amberlite XAD-4 in the collection of phenol. Freundlich isotherm equations and isosteric adsorption enthalpies for the four phenolic compounds indicate a physical adsorption process on the Amberlite XAD-4 and AM-1 resins. Column studies for phenol show that AM-1 resin has excellent adsorption and desorption performance.

Selective sorption of perfluorooctane sulfonate on molecularly imprinted polymer adsorbents

Perfluorooctane sulfonate(PFOS),as a potential persistent organic pollutant,has been widely detected in water environments,and has become a great concern in recent years.PFOS is very stable and difficult to decompose using conventional techniques.Sorption may be an attractive method to remove it from water.In this study,the molecularly imprinted polymer(MIP)adsorbents were prepared through the polymerization of 4-vinylpyridine under different preparation conditions in order to remove perfluorooctane sulfonate(PFOS)from water.The MIP adsorbents using perfluorooctanoic acid(PFOA)as the template had good imprinting effects and could selectively remove PFOS from aqueous solution.The sorption behaviors including sorption kinetics,isotherms,and effect of pH,salt,and competitive anions were investigated.Experimental results showed that the sorption of PFOS on the MIP adsorbents was very fast,pHdependent,and highly selective.The achieved fast sorption equilibrium within 1 h was attributed to the surface sorption on the fine adsorbents.The sorption isotherms showed that the sorption selectivity of PFOS on the MIP adsorbents decreased at high PFOS concentrations,which may be due to the double-layer sorption and the formation of PFOS micelles on the sorbent surface.The sorption of PFOS on the MIP adsorbents was mainly dominated by the electrostatic interaction between the protonated vinylpyridine on the adsorbent surface and the anionic PFOS.The prepared MIP adsorbents can potentially be applied in water and wastewater treatment for selective removal of PFOS.

MgO-based adsorbents for CO2 adsorption:Influence of structural and textural properties on the CO_2 adsorption performance

A series of MgO-based adsorbents were prepared through solution–combustion synthesis and ball-milling process.The prepared MgO-based powders were characterized using X-ray diffraction,scanning electron microscopy,N_2 physisorption measurements,and employed as potential adsorbents for CO_2 adsorption.The influence of structural and textural properties of these adsorbents over the CO_2 adsorption behaviour was also investigated.The results showed that MgO-based products prepared by solution–combustion and ball-milling processes,were highly porous,fluffy,nanocrystalline structures in nature,which are unique physico-chemical properties that significantly contribute to enhance their CO_2 adsorption.It was found that the MgO synthesized by solution combustion process,using a molar ratio of urea to magnesium nitrate（2：1）,and treated by ball-milling during 2.5 hr（MgO-BM2.5h）,exhibited the maximum CO_2 adsorption capacity of 1.611 mmol/g at 25℃ and 1 atm,mainly via chemisorption.The CO_2 adsorption behaviour on the MgO-based adsorbents was correlated to their improved specific surface area,total pore volume,pore size distribution and crystallinity.The reusability of synthesized MgO-BM2.5h was confirmed by five consecutive CO_2adsorption–desorption times,without any significant loss of performance,that supports the potential of MgO-based adsorbent.The results confirmed that the special features of MgO prepared by solution–combustion and treated by ball-milling during 2.5 hr are favorable to be used as effective MgO-based adsorbent in post-combustion CO_2 capture technologies.

Improved utilization of active sites for phosphorus adsorption in FeOOH/anion exchanger nanocomposites via a glycol-solvothermal synthesis strategy

Metal oxide/hydroxide-based nanocomposite adsorbents with porous supporting matrices have been recognized as efficient adsorbents for phosphorus recovery.Aiming at satisfying increasingly restrictive environmental requirements involving improving metal site utilization and lowering metal leakage risk,a glycol-solvothermal confined-space synthesis strategy was proposed for the fabrication of Fe OOH/anion exchanger nanocomposites(Fe/900s)with enhanced metal site utilization and reduced metal leakage risk.Compared to composites prepared using alkaline precipitation methods,Fe/900s performed comparably,with a high adsorption capacity of 19.05 mg-P/g with an initial concentration of 10 mg-P/L,a high adsorption selectivity of 8.2 mg-P/g in the presence of 500 mg-SO_(4)^(2-)/L,and high long-term resilience(with a capacity loss of~14%after five cycles),along with substantially lower Fe loading amount(4.11 wt.%)and Fe leakage percentage.Mechanistic investigation demonstrated that contribution of the specific Fe OOH sites to phosphate adsorption increased substantially(up to 50.97%under the optimal conditions),in which Fe(Ⅲ)-OH was the dominant efficient species.The side effects of an excessively long reaction time,which included quaternary ammonium decomposition,Fe OOH aggregation,and Fe(Ⅲ)reduction,were discussed as guidance for optimizing the synthesis strategy.The glycol-solvothermal strategy provides a facile solution to environmental problems through nanocrystal growth engineering in a confined space.

Sol-Gel Synthesized Adsorbents for Metal Separation

A series of organo-ceramic adsorbents have been synthesized by a sol-gel processing technique for metal ion extraction. These adsorbents generally have significantly high metal uptake capacities, good physical-chemical stabilities, and well-designed pore geometries compared to other pre-existing metalchelating ceramic-based adsorbents. This work describes the synthesis and evaluation of pyrazole and calix[4]arene crown adsorbents for selective separation of platinum, palladium, and gold and cesium ions, respectively, from solutions. These materials exhibit mesoporous properties with high surface areas and pore volumes. The sol-gel synthesis starting with precursor silanes and titania results in gel particles of desired pore characteristics and high capacity and stability. Characterization studies, such as adsorption isotherms, breakthrough curves for fixed bed operation, and material stability, show promising results for applications to metal sepation.

Removal of fluoride from water using titanium-based adsorbents

Three adsorbents including TiO_(2),Ti-Ce,and Ti-La hybrid oxides were prepared to remove fluoride from aqueous solution.The Ti-Ce and Ti-La hybrid adsorbents obtained by the hydrolysis-precipitation method had much higher sorption capacity for fluoride than the TiO_(2) adsorbent prepared through hydrolysis.Rare earth(Ce and La)oxides and TiO_(2) exhibited a synergistic effect in the hybrid adsorbents for fluoride sorption.The sorption equilibrium of fluoride on the three adsorbents was achieved within 4 h,and the pseudo-second-order model described the sorption kinetics well.The sorption isotherms fitted the Langmuir model well,and the adsorption capacities of fluoride on the Ti-Ce and Ti-La adsorbents were about 9.6 and 15.1 mg·g^(-1),respectively,at the equilibrium fluoride concentration of 1.0 mg·L^(-1),much higher than the 1.7 mg·g^(-1) on the TiO_(2).The sorption capacities of fluoride on the three adsorbents decreased significantly when the solution pH increased from 3 to 9.5.The electrostatic interaction played an important role in fluoride removal by the three adsorbents,and Fourier transform infrared(FTIR)analysis indicated that the hydroxyl groups on the adsorbent surface were involved in fluoride adsorption.

Chemisorption-Induced Resonance Frequency Shift of a Microcantilever

The autonomy and property of atoms/molecules adsorbed on the surface of a microcantilever can be probed by measuring its resonance frequency shift due to adsorption.The resonance frequency change of a cantilever induced by chemisorption is theoretically studied. Oxygen chemisorbed on the Si(100) surface is taken as a representative example.We demonstrate that the resonant response of the cantilever is mainly determined by the chemisorption-induced bending stiffness variation,which depends on the bond configurations formed by the adsorbed atoms and substrate atoms.This study is helpful for optimal design of microcantilever-based sensors for various applications.

THE SWELLING BEHAVIOR OF (W/O)/W LIQUID SURFACTANT MEMBRANE (Ⅰ) ADSORPTION OF SURFACTANT AT THE INTERFACE AND THE SWELLING CAUSED BY EMULSIFICATION

The concept of effective concentration of surfaetant in membrane phase has been proposed,considering the high ad-sorption density of the surfactant at the droplet interfaces in LSM system.The effective concentration of surfactant,C2,can be estimated by Eq.（7）—（9）.The swelling caused by emulsification during the initial dispersion process was investigated.The swelling rate wasmeasured by a density method.A model for estimating the"Emulsification" swelling rate,Fse,has been proposed,basedon a mechanism of swelling due to the entrainment of water resulted from the interracial turbulence and emulsification inthe initial dispersion process.It has been found that Eq.（26）gives excellent fit to the experimental data of Fujinawa,etal.and of the authors.

三维凹凸棒石对水中镍离子(Ⅱ)的吸附性能研究

以凹凸棒石为原料、N-氨乙基-3-氨丙基甲基二甲氧基硅烷为耦合剂、戊二醛为键合剂制备三维凹凸棒石吸附剂,通过改变吸附温度等外界条件,探究三维凹凸棒石的吸附性能。结果表明,Freundlich等温方程和准二级动力学方程能够更好地表现吸附热力学和吸附动力学中三维凹凸棒石对Ni(Ⅱ)的吸附过程。当25℃条件下,投加量为0.030 0 g、Ni(Ⅱ)的质量浓度为5 mg/L、p H为4,去除率可达99%以上。此外,吸附Ni(Ⅱ)离子主要以配位的形式进行,该吸附在工业及水质除Ni(Ⅱ)离子研究领域表现出潜在的实用价值。

金属有机骨架复合材料的合成及应用研究

为了提高金属有机骨架复合材料的吸附性,针对金属有机骨架复合材料的合成及应用展开研究。文章描述了金属有机骨架孔隙中负载离子液体,还分析了离子液体/金属有机骨架复合材料在吸附与萃取中、大气环境介质中以及水环境中的应用,通过相关研究可知,采用离子热合成法与后合成法制备离子液体/金属有机骨架复合材料,能够充分发挥离子液体与金属有机骨架比表面积大、孔径均匀、孔结构可调的优势,可为相关研究提供参考。

树脂吸附法处理高浓度混甲酚生产废水的研究

采用大孔吸附树脂ＣＨＡ－１１１，处理对申酚生产过程中产生的高浓度合酚废水，该树脂工作吸附量＞５０ｍｇ／ｍｌ，酚去除率＞９９％，ＣＯＤｃｒ去除率为５５％，除酚性能优于美国的ＡｍｂｃｔｌｉｔｃＸＡＤ－４。

具有高比表面积的极性吸附树脂的合成和性能研究

本文从树脂物理结构和化学结构着手，通过改变交联度，致孔剂用量，种类以及引入适量功能基因，分别合成了一系列具有高比表面积和极性的大孔吸附树脂，研究了它们对工业废水中β－萘碘酸的吸附－脱附性能．

巯基修饰Cu-MOFs材料的制备及其汞吸附性能

为高效对废水中的Hg^(2+)进行吸附,采用电化学法合成Cu-BDC金属有机骨架材料,并进行SH修饰,制备SH-Cu-BDC材料,用于对含Hg^(2+)废水的吸附研究。通过EDS与IR红外对修饰前后样品的表征分析可知,SH基团成功修饰到Cu-BDC材料上;N_2吸附实验表明,修饰后的SH-Cu-BDC材料出现微孔结构且比表面积增大;SEM分析表明,电化学合成Cu-BDC材料具有独特花状结构,修饰后SH-Cu-BDC材料表面均匀分布着触角状物质;10 mg SH-Cu-BDC对20 ml浓度为300 mg·L^(-1)的Hg^(2+)溶液进行吸附,当pH(28)5,60 min时吸附饱和,最大吸附量为585 mg·g-1;SH-Cu-BDC材料对Hg^(2+)的吸附符合拟二级反应动力学方程和Langmuir吸附等温模型,该吸附过程是以表面吸附为主的扩散过程,且符合单分子层吸附规律;吸附再生实验表明,SH-Cu-BDC作为吸附剂可重复使用,且具有一定的稳定性。

N,N’-亚甲基双丙烯酰胺交联淀粉微球的合成及吸附性能

以可溶性淀粉为原料，用反相悬浮法合成了N，N＇-亚甲基双丙烯酰胺交联淀粉微球ASM。最佳合成条件是可溶性淀粉2g，N，N’-亚甲基双丙烯酰胺0．2g，K2S2O80．04g，W／O相体积比1：3，反应时间2h，反应温度50℃。ASM外型规则，粒度10-20μm。探讨了成球机理，提出了交联反应主要在淀粉分子结构外围进行的推论并获得了实验支持。在25℃，ASM对Cu^2＋、Cr^3＋、Cd^2＋、Pb^2＋的饱和吸附量分别是2．75、2．20、0．88、0．77mmol·g^-1。HCl、ZnCl2使ASM对Cu^2＋的吸附量明显降低，MgCl2使吸附量略有降低。ASM的空间网状结构使金属离子容易深入其内部形成多点配位，配住吸附是ASM吸附金属离子的主要作用形式。

饱和ATP为原料合成多级孔ZSM-5沸石分子筛的制备与表征

研究以饱和ATP吸附材料为合成沸石分子筛的硅源,采用双模板法,用四丙基氢氧化铵(TPAOH)为微孔模板剂和十六烷基三甲基溴化烷(CTAB)为介孔模板剂直接合成多级孔ZSM-5沸石分子筛,通过XRD、SEM、比表面积及孔径分析仪进行N2吸附-脱附等手段对多级孔ZSM-5沸石分子筛表征测试分析。结果表明,饱和ATP吸附材料在180℃下,水热提纯12 h获得硅源,再加入TPAOH和CTAB进行初始凝胶反应,后移入水热反应釜中,控温180℃,水热晶化反应15 h,即得多级孔ZSM-5沸石分子筛。

表面活性剂辅助水热-热分解法制备介孔氧化铝纤维

以PEG(Mn=20000)为模板导向剂,尿素为沉淀剂,采用水热-热分解法制备了纳米介孔结构的氧化铝纤维,并对其吸附性能进行了研究.通过X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、热释重仪(TGA)和N2等温脱附-吸附分析,考察了介孔氧化铝纤维的相态、结构、形貌、比表面积和介孔特征.采用选择性催化还原(SCR)烟气脱硝装置对其吸附性能进行了研究.结果表明:以PEG为模板,采用简单的水热法就可得到(200～300)nm×(8～10)μm的碳酸铝铵纤维;经900℃煅烧2h得到比表面积为316m2/g、平均孔径为2.5nm的η-Al2O3介孔纤维,形貌基本不发生变化;SCR烟气脱硝测试显示,相比商品氧化铝粉末,合成的氧化铝介孔纤维有着更强的吸附性能,它的脱硝效率较之商品氧化铝粉末约提高了15%.

热管技术在吸附式制冷系统中的应用

主要介绍了热管技术在吸附式制冷系统中的国内外研究现状，分别对传统热管、热虹吸热管及分离式热管型吸附制冷系统的研究成果和典型样机做了阐述。为了减少双吸附器、双冷凝器、双蒸发器结构的硅胶一水吸附制冷机组的冷量损失，采用热虹吸热管技术实现了两蒸发器间工作状态的自动切换，该机组能够有效利用65-85℃范围内的低温热源，可提供6-1kW的制冷量，系统COP为0.31-0．43；采用同样技术的小型紧凑式固体吸附制冷空调机在典型空调工况下其COP为0.34；基于分离式热管技术的渔船用复合吸附制冰机解决了高温尾气及海水对吸附床的腐蚀问题，吸附床的加热解吸、冷却吸附及回热过程均由无外加驱动力的多功能热管完成。热管技术的应用强化了吸附机组的传热性能，进而提高了机组的制冷能力及工作可靠性。

从合成气脱羰基铁、羰基镍的方法

对从合成气脱羰基铁、镍的几种方法做了综述和对比 ,认为高温型保护剂是脱除羰基铁、镍较为有效的方法 。