铝污泥负载水合氧化铁-壳聚糖吸附水中Ni(Ⅱ)的研究

采用铁盐和壳聚糖(CS)对铝污泥(AlS)进行改性,制得了铝污泥负载水合氧化铁-壳聚糖复合吸附剂(AlS-HFO-CS),用该吸附剂对Ni(Ⅱ)进行吸附实验,研究了溶液pH值、温度、吸附时间以及竞争离子对吸附过程的影响。利用XRD、FTIR和SEM技术表征了吸附剂的形貌并探讨AIS-HFO-CS对Ni(Ⅱ)的吸附机理。结果表明:水合氧化铁和壳聚糖能成功负载在铝污泥上; Ni(Ⅱ)的吸附量随溶液pH的增大而增大,不考虑沉淀作用,最优吸附pH为5~6,吸附平衡时间为4 h; Freundlich、Langmuir模型对AlS-HFO-CS吸附Ni(Ⅱ)的拟合效果相近,说明对Ni(Ⅱ)的吸附可能同时涉及多层物理吸附和单层化学吸附;吸附过程更符合拟一级动力学模型,颗粒内扩散模型拟合结果显示内扩散和边界层扩散共同控制吸附速率;整个吸附过程是吸热且自发进行的,并且存在着竞争性,吸附剂对Ni(Ⅱ)的吸附易受Cr(Ⅵ)和Cu(Ⅱ)的影响。     

介孔氧化铝的制备及其对As~(5+)的吸附性能研究

以异丙醇铝为铝源,非离子表面活性剂P123为模板剂,采用溶胶-凝胶法于室温下制备出介孔氧化铝,并研究了该介孔氧化铝对As~(5+)的吸附性能。就材料焙烧温度、初始pH值、接触时间、吸附剂量和吸附温度对吸附性能的影响进行探讨。结果表明,介孔氧化铝对As~(5+)的吸附性能随材料焙烧温度的升高而降低;随吸附温度的升高吸附速率加快,吸附平衡时间缩短;吸附性能受溶液pH值影响较大,pH值=4.5时吸附容量达到最大,此时最大单分子层吸附容量为51.02mg/g。     

APTES改性羧甲基壳聚糖微球对铅离子吸附性能及机理研究

以羧甲基壳聚糖(CMCS)为基体,3-氨基丙基三乙氧基硅烷(APTES)作为改性剂,制备了用于吸附铅离子的改性羧甲基壳聚糖微球(A-CMCS)。使用扫描电子显微镜(SEM)、能谱仪(EDS)、傅里叶红外光谱仪(FT-IR)对吸附剂的表面形貌以及化学组成及结构进行了表征。研究了初始溶液的pH值、吸附温度以及铅离子的初始浓度对A-CMCS吸附性能的影响,结果表明当pH值为5、吸附温度为303 K时吸附剂对铅离子的吸附浓度达到最大为275.2 mg/g,比未改性之前的交联微球的吸附量提升43%。并使用吸附动力学以及等温吸附模型、FT-IR和X射线光电子能谱(XPS)对吸附机理进行了探究,其结果发现A-CMCS微球对铅离子的吸附过程是一个以化学吸附为主的单分子层吸附过程,其中氨基基团在整个吸附过程的起主导作用。     

污泥制备活性炭对 Pb(Ⅱ)和Ni(Ⅱ)的吸附和回收利用

在静态条件下研究了用污泥制备的活性炭吸附剂去除水溶液中Pb(Ⅱ)、Ni(Ⅱ)的效果,考察了溶液pH值、吸附时间、吸附剂用量和Pb(Ⅱ)、Ni(Ⅱ)的初始浓度对去除率的影响.结果表明,污泥制备的活性炭吸附剂对Pb(Ⅱ)、Ni(Ⅱ)具有较强的吸附性能,pH值是影响吸附的主要因素;吸附过程符合Langmuir吸附等温式;在试验条件下,其对Pb(Ⅱ)具有更高的去除能力.还探讨了吸附Pb(Ⅱ)、Ni(Ⅱ)后回收铅和镍的可行性.     

胶原纤维对水中Cr(Ⅵ)的吸附性能研究

胶原纤维(CF)作为吸附剂去除水中Cr(Ⅵ),研究了CF去除Cr(Ⅵ)时溶液pH值、温度、吸附剂用量和Cr(Ⅵ)初始浓度对去除效率的影响。结果显示,CF对Cr(Ⅵ)的去除率随溶液pH值降低而升高,在pH值为2.0时达到最大,随吸附剂用量增大而增大,随Cr(Ⅵ)初始浓度增加而减小,CF对Cr(Ⅵ)的吸附量随吸附剂用量增加而减小;随Cr(Ⅵ)初始浓度增加而增加,最后趋于稳定。吸附平衡时间为6h,最佳吸附温度为40℃。测定了吸附等温线和吸附动力学曲线,结果表明,Freundlich等温方程能更好地描述CF对Cr(Ⅵ)的吸附,吸附动力学符合伪二级吸附速率方程。FT-IR和SEM-EDS分析表明,CF表面含有大量氨基羧基及羟基等活性官能团,CF对Cr(Ⅵ)的吸附过程存在铬酸根阴离子与质子化活性官能团的静电吸附作用和离子交换作用。     

玉米芯接枝共聚物对Cu(Ⅱ)的吸附性能研究

采用NaHSO3/H2O2氧化还原引发体系,以甲基丙烯酸、丙烯酰胺为混合单体,合成了玉米芯接枝共聚物。研究了玉米芯接枝共聚物对Cu(Ⅱ)的吸附性能,详细考察了溶液初始酸度、时间、金属离子初始浓度、温度以及吸附剂的碱化处理对吸附性能的影响,结果表明:在pH低于4时,酸度对吸附性能影响显著;吸附速率快,在20min左右就能达吸附平衡;Cu(Ⅱ)初始浓度的增加及温度的升高有利于吸附的进行;碱化处理可使吸附量提高数倍。此外,吸附热力学的研究表明,该吸附过程是吸热过程。     

氧化石墨烯辐射接枝4-乙烯基吡啶及其对Cr(Ⅵ)吸附性能研究

通过辐照接枝法在氧化石墨烯(GO)的表面接枝4-乙烯基吡啶(4-VP)制备了一种新型Cr(Ⅵ)吸附剂,并研究了单体浓度和吸收剂量对4-VP接枝率的影响。结果表明:聚4-乙烯基吡啶成功接枝到GO表面。接枝产物对Cr(Ⅵ)具有较好的吸附性能,在40min即可达到吸附平衡,吸附机理为离子交换机理,吸附过程符合朗格缪尔吸附等温模型,理论最大吸附量为114.9mg/g。在pH=3.12时,吸附剂对Cr(Ⅵ)吸附量可以达到最大值99.8mg/g。     

纤维素基磁性吸附剂的制备及其吸附金属离子性能

为提高纤维素基吸附剂性能,使纳米纤维素(NCC)与乙二胺(EDA)反应制得NCC-EDA后,链接原位生成的Fe_3O_4制备了磁性吸附剂NCC-EDA/Fe_3O_4,并在结构表征的同时,考察了体系pH值、吸附时间、溶液浓度、吸附温度等对产物吸附金属离子性能的影响。结果表明,NCC-EDA/Fe_3O_4具有较大比表面积和孔隙,丰富的活性官能团及顺磁性能;最佳条件下对Pb~(2+)、Ni~(2+)及Cr~(6+)的最大吸附量为352.10,265.96和291.55mg/g;吸附过程为单分子层吸附,吸附行为符合拟二级动力学方程及Langmuir吸附等温线,具有吸附速率高及重复使用性能优等特点。     

壳聚糖/明胶复合微球的制备及对铬离子的吸附性能

壳聚糖具有较高的吸附性能,明胶高分子链上有氨基、羟基、羧基等活性基团,对六价铬Cr(Ⅵ)具有一定的吸附螯合作用。本工作采用乳化交联法制备壳聚糖/明胶复合微球,以微球对Cr(Ⅵ)的去除率为指标,通过正交实验优化微球制备条件,并利用扫描电镜对微粒形貌进行表征。在研究复合微球对水体中Cr(Ⅵ)的吸附性能时,考察了吸附剂用量、pH值、吸附时间、温度等因素对吸附容量的影响。结果表明,壳聚糖/明胶微球的最佳制备条件为壳聚糖/明胶质量比1∶2,乳化时间40 min,乳化剂span80用量6 mL,水油比1∶7(体积比),乳化温度60℃;最佳吸附条件为:吸附剂用量2 g/L,pH值4,温度35℃,吸附时间120 min,在该条件下微球对Cr(Ⅵ)的去除率为95.5%。     

谷壳对水体中刚果红的吸附研究

本文研究了谷壳对水体中阴离子染料刚果红的吸附行为,分别考察了平衡时间、溶液pH值、吸附剂用量、刚果红溶液初始浓度及温度等因素对吸附性能的影响。     

Governing factors for motor oil removal from water with different sorption materials

This paper has been focused on the sorbent efficiency for motor oil removal from water. Two types of sorbents were investigated: organic and inorganic. Natural wool fibers (NWFs) and recycled-wool-based nonwoven material (RWNM)) were tested as organic type of sorbents. Sepiolite, bentonite and zeolite have been chosen as representative inorganic sorbents. Sorption was carried out in batch sorption system. Efficiency of oil removal was determined by measuring the oil concentration before and after the sorption process. Extractive-gravimetric method and refractive index determination have been applied as analytical methods for determination of oil concentration in water. Governing factors for sorbent efficiency were proposed, analysed and compared. It was concluded that sorption process is mostly affected by mass of sorbent, sorption time, temperature and pH value of water. NWFs, which were the most efficient sorbent showed maximal efficiency and maximal sorption capacity: 0.1 g of NWFs after 10 min at 20 degrees C and pH 8.00 sorbed 3.3 g of motor oil from 300 mL of water polluted with 4.5 g of motor oil. Maximal efficiency for all sorbents investigated was reached after 30 min of sorption processes, it was 95.0% for NWF, 43.0% for NRWM, 20.7% for sepiolite, 19.6% for bentonite and 21.2% for zeolite. Physical adsorption onto all sorbents is a favorable process (sorption efficiency decrease with increasing temperature) while sorption onto bentonite and zeolite is a result of both physical adsorption and chemisorption (sorption efficiency increase with increasing temperature, up to 80 degrees C).     

An imprinted organic–inorganic hybrid sorbent for selective separation of copper ion from aqueous solution

A new organic–inorganic hybrid sorbent was prepared by a double-imprinting approach for the selective separation of Cu(II) from aqueous solution. In the prepared hierarchically imprinted sorbent, both Cu(II) and surfactant micelles (cetyltrimethylammonium bromide) were used as templates. The sorbent was prepared through self-hydrolysis, self-condensation, and co-condensation of the crosslinking agent (tetraethoxysilane) and the functional precursor (3-aminopropyltrimethoxysilane) in an alkaline media followed by gelation. The adsorption property and selective recognition ability of the sorbents were studied by equilibrium-adsorption method. Results showed that in the presence of Zn(II) the biggest selectivity coefficient of the imprinted sorbents for Cu(II) was over 500, which is much higher than those of non-imprinted sorbents. The largest relative selectivity coefficient (k′) of the ion-imprinted functionalized sorbent between Cu(II) and Zn(II) was over 500. The uptake capacities and the selectivity coefficients of the hierarchically imprinted sorbent were much higher than those of the sorbent prepared without CTAB template. Furthermore, the new imprinted sorbent possessed a fast kinetics for the removal of Cu(II) from aqueous solution with the saturation time less than 10 min, and could be used repeatedly. This sorbent has been successfully applied to the separation and determination of the trace Cu(II) in real water samples and those spiked with standards. This new sorbent can be used as an effective solid-phase extraction material for the highly selective preconcentration and separation of Cu(II) in environmental samples.     

水热辅助表面接枝印迹法制备Cd(Ⅱ)离子印迹硅胶及其性能研究

采用水热辅助表面接枝印迹技术,以Cd(Ⅱ)离子作为模板,巯基丙基三甲氧基硅烷为功能分子,环氧氯丙烷为交联剂,在硅胶表面制备出高容量的Cd(Ⅱ)离子印迹硅胶材料,利用红外光谱仪、扫描电镜、热重分析仪等进行了表征,采用平衡吸附法研究了印迹硅胶材料的吸附性能和选择识别能力。结果表明,印迹硅胶材料和非印迹硅胶材料的最大吸附量分别为42.5和22.1mg/g;印迹硅胶材料对Cd(Ⅱ)离子具有较强的选择识别能力,对Cd(Ⅱ)离子的吸附行为更符合Langmuir模型,20min即可达到吸附平衡,符合准二级动力学方程,pH值在4～8范围内,保持了较好的吸附容量;重复使用时性能较好。     

Removal of arsenic from water using granular ferric hydroxide: macroscopic and microscopic studies

Removal of arsenate from water using granular ferric hydroxide (GFH) was investigated under different pH and As(V) loading conditions, using batch equilibrium adsorption, FTIR, and EXAFS methods. The arsenate adsorption envelopes on GFH exhibited broad adsorption maxima when the initial As(V) concentration was less than 500 mg/L at sorbent concentration of 10 g/L. As the initial As(V) concentration increased to 500, 1000 or 2000 mg/L for the same sorbent concentration, distinct adsorption maxima appeared and shifted to lower pH. Acidimetric-alkalimetric titration and arsenic adsorption isotherm data indicated that the surface of GFH is high heterogeneous. FTIR spectra revealed that complexes of two different structures, bidentate and monodentate, were formed upon the adsorption of arsenate on GFH, and bidentate complexes were only observed at pH values greater than 6. The EXAFS analyses confirmed that arsenate form bidentate binuclear complexes with GFH at pH 7.4 as evidenced by an average Fe-As(V) bond distance of 3.32 A.     

Novel Magnetic Cobalt Cyanoferrate Nanoparticles as Potential Sorbent for Solid-Phase Extraction of Radionuclides from Aqueous Samples

A composite material based on magnetite and K₂[CoFe(CN)₆] was prepared. Structural and morphological studies of the sorbent were carried out, and the specific surface area was determined. The crystal structure of the material was studied by X-ray diffraction, and the composition was evaluated by energy-dispersive X-ray spectroscopy. Sorption of radionuclides was studied in batch experiments in relation to pH of the solution, mass of the adsorbent, and contact time. The adsorption kinetics was examined, the adsorption isotherm was constructed, and the adsorption capacity was determined. The resistance of the material to radiation to a dose of 250 kGy was evaluated. The material efficiently removes Cs and Am radionuclides from aqueous solutions. The sorbent seems to be sufficiently stable for practical use in the treatment of radioactive waste.     

The adsorption kinetics of the cationic dye, methylene blue, onto clay

In this study, adsorption kinetics of a cationic dye, methylene blue, onto clay from aqueous solution with respect to the initial dye concentration, temperature, pH, mixing rate and sorbent dosage were investigated. In order to understand the adsorption mechanism in detail, zeta potentials and the conductivities of clay suspensions at various pH (1-11) and cation exchange capacity (CEC) were measured. Porosity and BET surface area of clay studied were determined. The results showed that the adsorption has been reached to equilibrium in 1 h. It was found that the amount adsorbed of methylene blue increases with decreasing temperature and also with increasing both sorbent dosage and increasing initial dye concentration. Adsorption capacity decreases with increasing pH, except for the natural pH (5.6) of clay suspensions. The adsorption kinetics of methylene blue has been studied in terms of pseudo-first-order, pseudo-second-order sorption and intraparticle diffusion processes thus comparing chemical sorption and diffusion sorption processes. It was found that the pseudo-second-order mechanism is predominant and the overall rate of the dye adsorption process appears to be controlled by the more than one-step.     

Novel nanocomposites based on gelatin/HPET/chitosan with high performance acid red 150 dye adsorption

In this study, the properties of gelatin and chitosan are combined in the presence of hydrolyzed poly(ethylene terphthalate), HPET, and laponite to produce a novel hybrid natural-synthetic material for anionic dyes removal applications. Adsorption studies of acid red 150 from aqueous solution with respect to the initial dye concentration, temperature, time, pH, and sorbent dosage were investigated. The Langmuir adsorption model was applied to describe the equilibrium isotherms. The prepared nanocomposites were characterized using different techniques, such as FTIR, DSC, SEM, and TEM. The suitability of the adsorbent was tested by fitting the adsorption data with Langmuir isotherm. The results showed that the adsorption of AR150 was increased with an increasing in both of the dye and chitosan concentrations.     

镉离子印迹硅胶的制备与吸附性能

采用表面印迹技术和溶胶-凝胶法,以Cd(Ⅱ)离子作为印迹离子,硫氰基丙基三甲氧基硅烷为功能分子,环氧氯丙烷为交联剂,在硅胶表面制备Cd(Ⅱ)离子印迹聚合物(IIP-TCPTS/SiO2),并利用平衡吸附法研究了聚合物吸附性能和选择识别能力。结果表明,最大吸附量为16.7 mg/g;20 min即可达到吸附平衡;当pH值在5.4~7.8范围内,印迹聚合物保持了较好的吸附容量;印迹聚合物对Cd(Ⅱ)离子具有较强的选择性识别能力;重复使用时性能稳定。     

Removal of chromium and toxic ions present in mine drainage by Ectodermis of Opuntia

This work presents conditions for hexavalent and trivalent chromium removal from aqueous solutions using natural, protonated and thermally treated Ectodermis of Opuntia. A removal of 77% of Cr(VI) and 99% of Cr(III) can be achieved. The sorbent material is characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, infrared spectroscopy, thermogravimetric analysis, before and after the contact with the chromium containing aqueous media. The results obtained from the characterization techniques indicate that the metal ion remains on the surface of the sorbent material. The percentage removal is found to depend on the initial chromium concentration and pH. The Cr(VI) and Cr(III) uptake process is maximum at pH 4, using 0.1g of sorbent per liter of aqueous solution. The natural Ectodermis of Opuntia showed a chromium adsorption capacity that was adequately described by the Langmuir adsorption isotherm. Finally, an actual mine drainage sample that contained Cd, Cr, Cu, Fe Zn, Ni and Pb was tested under optimal conditions for chromium removal and Ectodermis of Opuntia was found to be a suitable sorbent material. The use of this waste material for the treatment of metal-containing aqueous solutions as well as mine drainage is effective and economical.     

Biosorption of Astrazone Blue basic dye from an aqueous solution using dried biomass of Baker's yeast

In this study dried biomass of Baker's yeast, Saccharomyces cerevisiae, is used as a sorbent for Astrazone Blue basic dye aqueous solution. Factors affecting the adsorption process: dye concentration, contact time, temperature and pH were investigated. The equilibrium concentration and the adsorption capacity at equilibrium were determined using three different sorption models namely: Langmuir, Freundlich and Temkin isotherms. It was found that increasing temperature and pH result in higher dye loadings per unit weight of the sorbent. The results gained from this study were described by Langmuir isotherm model better than Freundlich and Temkin isotherm models. The calculated heat of adsorption of the dye-yeast system indicates that the bio-sorption process is taking place by chemical adsorption and has an endothermic nature. The maximum adsorption capacity at 30 degrees C and pH 7 was calculated as 70 mg/g for dried biomass of Baker's yeast compared to 18.5mg/g for commercial granular activated carbon, indicating that dried biomass of Baker's yeast can be considered as a good sorbent material for Astrazone Blue solution.