脱硫石膏吸附水体中重金属离子行为的研究

利用工业废弃物脱硫石膏(flue gas desulfurization gypsum,FGDG)作为吸附剂,在静态吸附条件下,从温度、pH值等方面考察了FGDG对多种重金属离子的吸附能力以及多种重金属离子共存在下的吸附过程.基于水合半径和带电量对于吸附过程的影响,初步提出一个传质模型.在多元重金属离子存在的体系中,水合半径和电荷大小对竞争吸附结果有显着影响,五种重金属离子竞争能力顺序表现为:Pb2+＞Cr3+＞Cd2+＞Mn2+＞Cu2+. Langmuir模型推测吸附模型中化学吸附主要属于单层吸附过程,Freundlich模型能够描述FGDG与重金属离子物理吸附属于多层吸附过. XRD定性分析后,FGDG与重金属离子可形成Cu-S,Cd-S,Cr-S,Mn-S,Pb-S.     

吸附法脱除废水中四环素的研究进展

四环素(TC)是目前生产和使用量比较大的一种广谱抗生素,其化学性质较稳定且难以代谢而容易富集于土壤和水体中。抗生素的滥用不仅使细菌耐药性增加,而且会产生抗性基因并诱导产生超级细菌,因此对含TC废水的无害化处理刻不容缓。吸附法具有易操作、去除率高、经济、环保等优点,被广泛认为是一种高效去除抗生素方法。吸附法去除废水中四环素所用的吸附材料类型不同、种类繁多,本工作总结了炭质材料、金属有机框架材料和矿物材料这三类常用吸附剂,列举了上述材料对TC的吸附容量,分析了p H值、温度、离子强度和其他因素对TC吸附过程的影响。在此基础上,分析这三类材料吸附TC时不同吸附动力学和热力学模型的拟合情况,发现大多数材料的吸附动力学采用准二级动力学模型而吸附热力学采用Freundlich热力学模型能更好地描述其吸附过程。阐述了去除TC过程中所涉及的机理。对这三类材料吸附TC研究中存在的优势与不足进行比较,展望了今后的研究重点,为加快制备更经济、高效、可再生的TC吸附材料提供参考。     

脱硫石膏改性固体胺复合材料的制备及脱碳性能

将榴莲壳碳化制备生物炭（BC）,与硅钙渣混合作复合载体,在其表面浸渍负载五乙烯六胺（PEHA）,并加入含水分的脱硫石膏（FGDG）,得到胺功能化的含水CO₂固体吸附剂,与不含脱硫石膏的吸附剂相比吸附活性明显改善。通过FT-IR、TGA、SEM及N₂吸脱附等手段对吸附剂进行了表征,并在固定床反应器中考察了吸附剂脱硫石膏含量、吸附温度和CO₂浓度对吸附性能的影响。结果表明,脱硫石膏中水的存在改变了氨基与CO₂的相互作用机理。当脱硫石膏含量为30%、吸附温度为85℃时,CO₂最大吸附量为2.33 mmol/g。经12次循环再生后吸附量仅下降了4.2%,表现出良好的吸附稳定性。Clausius-Clapeyron方程计算的等量吸附热介于物理与化学吸附热之间,说明吸附过程中物理与化学作用同时进行。用多个动力学模型对实验数据进行拟合,pseudo-first-order与pseudo-second-order模型均不能准确拟合实验数据,而Avrami模型可较好地拟合整个吸附过程,进一步验证BC/SCS-PEHA-30% FGDG的CO₂吸附过程并非单纯的物理或化学吸附,而是两者同时发生。     

农业废弃物香芋柄对含Mn2+废水的吸附

以废弃香芋柄作为新型生物吸附剂,通过静态吸附实验,研究了pH、温度、吸附时间、Mn2+初始浓度等因素对香芋柄吸附Mn2+的影响,分析了吸附过程的热力学、动力学和等温吸附规律. 结果表明,溶液初始pH=4,香芋柄用量6 g/L,30℃下吸附60 min,溶液中Mn2+吸附去除率达90.79%以上,吸附容量高达18.16 mg/g. 应用Langmuir和Freundlich模型描述香芋柄对Mn2+的吸附过程,结果显示Freundlich吸附等温线拟合效果更好. 吸附动力学实验数据符合准二级动力学模型. 计算得到热力学参数DG<0, DH>0, DS>0,表明该吸附过程是自发和吸热的过程.     

PAMAM接枝稻草对Nd3+、Sm3+、La3+的吸附特性

以环氧氯丙烷为交联剂,将聚酰胺胺树状大分子(PAMAM)接枝到稻草基体上,利用FTIR、SEM、XRD、TG等对其结构进行了表征和分析。考察了其对Nd~(3+)、Sm~(3+)、La~(3+)稀土金属离子的吸附性能,探讨了吸附时间、稀土金属离子浓度、吸附温度、溶液pH等因素对吸附性能的影响。同时对吸附过程的动力学、吸附等温线和吸附热力学进行了研究。结果表明,所制备的吸附剂对Nd~(3+)、Sm~(3+)、La~(3+)稀土金属离子的吸附平衡时间约为4 h,平衡吸附量分别为47.14、40.11和50.12 mg/g。吸附过程符合拟二级动力学模型和Freundlich等温线,表明此吸附过程是属于化学吸附过程。吸附热力学研究表明,此吸附过程是自发进行的,同时吸附过程是一个混乱度增加的熵增过程。     

有机磁性膨润土对环丙沙星和四环素的吸附性能

为了提高磁性膨润土（magnetic bentonite,MB）的磁分离性能,达到高效去除抗生素的目的,本文采用羧甲基纤维素（sodium carboxymethyl cellulose,CMC）和壳聚糖（chitosan,CS）相互作用所生成的有机共聚膜（chitosan/sodium carboxymethyl cellulose copolymer film,CC）对MB进行联合修饰,制得双有机修饰的有机磁性膨润土（magnetic bentonite/carboxymethyl cellulose-chitosen composite,MB-CC）,同时进行了MB-CC对环丙沙星（ciprofloxacin,CIP）和四环素（tetracyclines,TC）的吸附性能研究。表征结果表明,磁性Fe₃O₄纳米粒子和有机共聚膜CC成功地固定在MB上;经过CC改性,提高了Fe₃O₄的稳定性和对CIP及TC的去除性能。吸附结果表明,在pH为5、温度为25℃的条件下,MB-CC对CIP和TC的吸附容量（182mg/g和189mg/g）高于MB对CIP和TC的吸附容量（147mg/g和136mg/g）。经过5次循环,MB-CC对CIP和TC的去除率仍然保持在90%以上。与Freundlich模型相比较而言,CIP和TC在MB和MB-CC上的吸附行为更加符合Langmuir模型;吸附过程可由准二级动力学模型描述,说明吸附速率主要由化学吸附控制。MB-CC对CIP和TC的吸附机理主要包括孔扩散、阳离子交换和静电吸引作用。综上所述,MB-CC具有合成简单、高效等优点,是一种很有前途的抗生素废水去除方法。     

Comprehensive evaluation of antibiotic tetracycline and oxytetracycline removal by Fe-metal organic framework/biopolymer-clay hydrogel

Tetracycline (TC) and oxytetracycline (OTC) are antibiotic compounds increasingly detected in various water sources. In this study, Fe-metal organic framework incorporated biopolymer-clay hydrogels (CAMIL-MMT and CAMIL-SEP) were prepared to remove TC and OTC from water. The physicochemical properties of the as-prepared hydrogels were thoroughly characterized, and the effect of various operating parameters on the adsorption performance was systematically examined. The CAMIL-MMT hydrogel showed the maximum adsorption capacity for TC and OTC (24.59 and 26.14 mg/g, respectively) compared to the CAMIL-SEP and other forms of biopolymer hydrogel precursors. The effects of the contact time and initial concentration on TC and OTC adsorption by CAMIL-MMT and CAMIL-SEP hydrogels were well suited to the pseudo-second-order kinetics and Freundlich isotherm models. The adsorption performance of CAMIL-MMT and CAMIL-SEP hydrogels slightly decreased with an increase in solution pH, while it was not much influenced by the co-existing anions. The thermodynamic study indicated that the reactions for the uptake of TC and OTC were spontaneous and highly favorable. Moreover, the as-synthesized CAMIL-MMT and CAMIL-SEP hydrogels demonstrated strong potential for reuse in TC and OTC removal with high reusability and strong stability. The photocatalysis study revealed that residual TC and OTC after adsorption could be further degraded by CAMIL-MMT and CAMIL-SEP hydrogels under visible light irradiation. From the above-mentioned results, the as-synthesized CAMIL-MMT and CAMIL-SEP hydrogels are promising to be considered alternative materials for the adsorptive and photocatalytic removal of TC and OTC in practical application of water and wastewater treatment.     

LS-303B大孔树脂吸附白藜芦醇的研究

研究了LS-303B大孔吸附树脂对白藜芦醇的吸附性能。结果表明,pH2~8范围内,LS-303B大孔吸附树脂对白藜芦醇具有良好的吸附性能,实验条件下,静态吸附平衡时间60 min。等温吸附符合傅劳因德利希(Freundlich)和朗格缪尔(Langmuir)方程,吸附过程为自发热力学放热过程。柱长5.0 cm,内径1.0 cm,内装3.00 g LS-303B树脂的吸附柱,对流速为5.0 mL/min,浓度为20μg/mL白藜芦醇溶液(50 mL)的吸附率为99.45%,吸附的白藜芦醇用80%的乙醇溶液可以完全洗脱。     

Kinetics,equilibrium and thermodynamic studies on the adsorptive removal of nickel,cadmium and cobalt from wastewater by superparamagnetic iron oxide nanoadsorbents

Because of its unique properties, such as specific functionality and large specific surface area, iron oxide nanoadsorbents had showed potential for energy and environmental applications. This work investigated the adsorptive removal of different metal ions from wastewater by superparamagnetic iron oxide nanoadsorbents (Fe₃O₄). Batch‐adsorption technique was employed to assess the kinetic behaviour and adsorption equilibrium of cadmium, cobalt and nickel. Accordingly, the effect of the following variables on the adsorption reaction was tested, namely: solution pH, contact time and temperature. Metal ion adsorption was found to be highly pH dependent with a maximum uptake achieved around pH 5.5. Kinetic studies showed that adsorption was fast and equilibrium was achieved in less than 60 min. The external mass transfer kinetic model was applied to the experimental results and provided reasonable overall volumetric mass transfer coefficients. Adsorption isotherms were determined and appropriately described by the Freundlich and Langmuir models, with a better fit to the Freundlich model. The amount of metal ion adsorbed increased as the temperature increased, suggesting an endothermic adsorption process. The thermodynamics studies indicated that the adsorption process was spontaneous and endothermic in nature. © 2011 Canadian Society for Chemical Engineering     

阴离子交换树脂对磺基水杨酸的吸附解吸性能

用阴离子交换树脂(D201)吸附的方法研究了磺基水杨酸的富集及回收。测定了溶液的pH值、温度、吸附时间等因素对吸附的影响,探讨了吸附的热力学和动力学特性。结果表明:D201树脂在pH=2—11时,吸附能力最好,等温吸附服从Freundlich经验式,吸附动力学符合Lagergren一级速率方程,颗粒内扩散是速率控制步骤之一,膜扩散也共同影响着吸附过程。在295—313 K条件下,磺基水杨酸吸附质量分数为380—420 mg/g的吸附焓变为-13.73—-8.422 kJ/mol,自由能变为-19.89—-21.45 kJ/mol,吸附熵变为20.88—41.62 J/(K.mol),吸附速率常数为0.025 3—0.056 5 min-1,吸附活化能为34.04 kJ/mol。315 K下用质量分数10%NaCl+2%NaOH溶液可定量洗脱,洗脱率达99%。     

Commercial Diatomite for Adsorption of Tetracycline Antibiotic from Aqueous Solution

Extensive use of antibiotics in human therapy and farming industry has resulted in their accumulation and potential hazards to the environment. In this study, diatomite, which is a siliceous rock with large surface area and high adsorptivity towards organic compounds, was used to adsorb the antibiotic tetracycline (TC) from aqueous media. The adsorption kinetics, isotherms, thermodynamics, and effects of the adsorbent amount and ionic strength were evaluated in batch adsorption experiments. The adsorption of TC onto diatomite followed the pseudo-second-order kinetics model, and the sorption equilibrium was reached in 120 min. The perfect adsorbent amount could be selected within the range of 1 ? 20 g·L^?1. The equilibrium data at different temperatures was satisfactorily fitted to the Langmuir isotherm equation with high R² above 0.999, and the maximum monolayer adsorption capacity of 303.03 mg·g^?1 was obtained at 318 K using 1 g·L^?1 diatomite. Thermodynamic parameters showed that the adsorption reaction was spontaneous and endothermic. Moreover, the adsorption of TC was insignificantly affected by the ionic strength of 0.05-1% NaCl and CaCl₂, indicating that diatomite has a potential practical application as adsorbent media for removing TC from real water.     

Biosorption of Zinc on Palm Tree Leaves: Equilibrium,Kinetics, and Thermodynamics Studies

Abstract

The efficiency of using palm tree leaves to remove zinc ions from aqueous solution was studied. Adsorption isotherms, kinetics, and thermodynamics studies were conducted. The influence of different experimental parameters, such as equilibrium pH, shaking rate, temperature, and the presence of other pollutants such as chelating agents on the biosorption of zinc on palm tree leaves was investigated.

Batch biosorption experiments showed that palm tree leaves used in this study proved to be suitable for the removal of zinc from dilute solutions where a maximum uptake capacity of 14.7 mg/g was obtained at 25°C. Zinc biosorption on palm tree leaves was found to be highly pH dependent. The biosorption process was found to be rapid with 90% of the adsorption completed in about 10 min. Dynamics studies of the biosorption of zinc on palm tree leaves showed that the biosorption process followed the pseudo second‐order kinetics with little intraparticle diffusion mechanism contribution. The equilibrium results indicated that zinc biosorption on palm tree leaves could be described by the Langmuir, Freundlich, Gin et al., and Sips models. Using the Langmuir equilibrium constants obtained at different temperatures, the thermodynamics properties of the biosorption (ΔG⁰, ΔH⁰, and ΔS⁰) were also determined. The values of these parameters indicated the spontaneous and endothermic nature of zinc biosorption on palm tree leaves.     

改性麦秸对U(VI)的吸附性能及机理

通过静态吸附实验,研究了麦秸改性剂、溶液pH值、吸附时间、麦秸投加量、U(VI)初始浓度、温度对麦秸吸附U(VI)的影响,并对吸附机理进行了探讨. 结果表明,经NaOH改性后的麦秸吸附率有了显著提高,改性后比改性前吸附率提高约52%;在303 K、pH值3.0时,吸附于120 min左右趋于平衡,平衡吸附量为1.20 mg/g;吸附过程为自发进行的吸热反应,符合Freundlich方程;吸附动力学过程可用准二级吸附速率方程来描述;改性麦秸对U(VI)的吸附表现为配位络合吸附机理.     

Effect of the chelating agents on bio-sorption of hexavalent chromium using Agave sisalana fibers

The current work is focused on the study of the bio-sorption of hexavalent chromium from aqueous solution using sisal natural fiber(Agave sisalana) treated by various chelating agents(ligands) such as urea(UR),thiocarbamide(TC), ethylenediaminetetraacetic acid(EDTA), and diphenyl carbazide(DCZ). The fiber treatments were investigated using Fourier Transform Infrared Spectroscopy(FTIR) and Scanning electron microscope(SEM). The kinetics of chromium bio-sorption was studied in batch presses under the effect of some physicochemical factors such as the nature of chelating agent(F@UR, F@TC, F@DCZ, and F@EDTA),adsorbent dose(2–10 g·L~(-1)), chromium initial concentration(100–500 mg·L~(-1)), solution pH(1–6), and batch temperature(20 ℃–50 ℃). This study resulted in an optimum adsorption at a chromium initial concentration of 100 mg·L~(-1), at pH 2, and at 20 ℃. The obtained results showed clearly that the treatment with chelating agent boosts the adsorptive capacity of A. sisalana fibers Cr(VI) 10.9 mg·g~(-1) to 58.6 mg·g~(-1). The modeling study showed that the adsorption kinetics obey the pseudo-second-order model, with an R2 in the range of 0.991 and 0.999. The bio-sorption isotherms followed the Langmuir model; the maximum uptake capacity of(F@N, F@UR,F@TC, F@DCZ, and F@EDTA) was found to be respectively, 12.3 mg·g~(-1), 25.33 mg·g~(-1), 28.73 mg·g~(-1),42.54 mg·g~(-1), and 61.45 mg·g~(-1). The determined adsorption thermodynamics parameters such as enthalpy,free energy, and entropy showed that the adsorption process is exothermic, spontaneous, and has a stable configuration.     

ADSORPTION OF COBALT ONTO GRAPHITE NANOCARBON–IMPREGNATED ALGINATE BEADS: EQUILIBRIUM,KINETICS, AND THERMODYNAMICS STUDIES

A novel adsorbent was developed impregnating graphite nanocarbon (GNC) into alginate beads (AB) for efficient cobalt (Co(II)) removal from an aqueous solution. Physicochemical and spectroscopic properties of graphite nanocarbon–impregnated alginate beads (ABGNC) were characterized and compared with those of AB. Co(II) adsorption on ABGNC was quantitatively evaluated by determining kinetics and thermodynamics parameters. The Co(II) adsorption capacity onto ABGNC was highest at neutral pH condition. Increasing the temperature from 288 to 318 K resulted in a 2.5-fold higher Co(II) adsorption onto AB, while thermal dependence of Co(II) adsorption on ABGNC was not found. Kinetic studies showed an applicability of the pseudo-second-order kinetic model for both AB and ABGNC. Monolayer adsorption was the dominant mechanism of Co(II) adsorption on both AB and ABGNC. Thermodynamic studies revealed that Co(II) adsorption was an endothermic and spontaneous process. Positive values of entropy indicate randomness in solid/aqueous phases, and mean free energy (E _a ) fits in the range of chemisorption.     

Magnetic Multi-Wall Carbon Nanotubes for Methyl Orange Removal from Aqueous Solutions: Equilibrium,Kinetic and Thermodynamic Studies

The magnetic iron oxide nanoparticles (SPION) were prepared using the co-precipitation method. The magnetically modified multi-wall carbon nanotubes (MWCNT) were obtained by the same method. The magnetic nanoparticles were used as adsorbents for methyl orange (MO) removal from aqueous solutions. The surface properties of adsorbents were analyzed by XRD, TGA, FTIR, and SEM. The adsorption was carried out on batch type. The kinetic, equilibrium and thermodynamics parameters were obtained by experimental results. The maximum adsorption capacity was obtained at pH 3 for both of the adsorbents. Theoretical adsorption capacities were found as 0.31 mg/g for SPION and 10.54 mg/g for MWCNT/SPION composites from Langmuir isotherm parameters. The MWCNT/SPION composites can adsorb 95% of methyl orange from water. The kinetic parameters and thermodynamic parameters were calculated.     

Heavy metals adsorption on some iminodiacetate chelating resins as a function of the adsorption parameters

The adsorption properties of some novel chelating resins (CRs) bearing iminodiacetate groups for removal of heavy metal ions like: Cu(II), Co(II) and Ni(II) from aqueous solutions comparative with the commercial resin Amberlite IRC-748 have been studied in this work by a batch equilibrium technique. Quantitative analysis for adsorption was conducted using UV–vis spectroscopy to investigate the kinetics, adsorption isotherm and thermodynamics of the removal process considering equilibration time, pH, metal ion concentration and temperature as controlling parameters. The metal adsorption capacities, at pH 5, were in the order Cu(II) > Ni(II) > Co(II), for both the CR with 10 wt.% DVB (CR-10) and the commercial resin Amberlite IRC-748. The adsorption capacities on CR-10 were higher for Ni(II) and Co(II) ions, but lower for Cu(II) ions compared with Amberlite IRC-748. Both Freundlich and Langmuir isotherms well fitted on the adsorption results of Cu(II), Ni(II) and Co(II) ions on all iminodiacetate resins.     

利用环糊精处理含酚废水的研究

文章利用β-环糊精(β-CD)的结构和性能对含苯酚废水进行处理,通过实验考查了吸附时间、pH、温度、用量、废液浓度等因素对吸附率的影响,得出实验的最佳工艺条件为:吸附时间为240 min,pH为5~7,β-CD用量为4 g/L,苯酚初始浓度为100 mg/L,吸附温度40℃,最高吸附率可以达到42.5%。进一步研究在30℃条件下,β-CD吸附苯酚废水过程符合Freundlieh吸附模型。     

ZH-03树脂对苯酚和2,4-二氯苯酚的吸附机理研究

在静态条件下,研究了水溶液中新型树脂ZH-03吸附苯酚和2,4-二氯苯酚的热力学特性,测定了在288k、303k、318k和下降到288k温度下的吸附等温线。结果表明,在稀溶液中ZH-03吸附剂对苯酚和2,4-二氯苯酚的吸附同时符合Langm u ir和F reund lich模型。该树脂对苯酚的吸附是一个放热过程,而对2,4-二氯苯酚的吸附属于吸热过程,同时不同温度下的吸附等温线和热力学计算结果都证明了在树脂ZH-03对2,4-二氯苯酚吸附行为中存在着化学吸附。     

茶叶质铁对苯酚废水的吸附性能及动力学研究

研究了茶叶质铁对苯酚的吸附性能及吸附动力学.探讨了溶液的初始浓度、pH值、时间和温度对吸附性能的影响,并采用Langmuir等温吸附方程和-dc/dt=κcn动力学吸附速率方程探讨了等温吸附过程和吸附动力学过程.结果表明:茶叶质铁对苯酚吸附时,溶液最佳pH为9.0,苯酚初始浓度为200mg/L,吸附温度范围为50℃,吸...