沟戈登氏菌对重金属的生物吸附-浮选和解吸性能

用沟戈登氏菌作吸附剂,研究了采用生物吸附-浮选和解吸法从水溶液中去除和回收重金属的过程,并对生物吸附浮选机理进行了分析.结果表明,沟戈登氏菌对各种重金属离子的选择性为Hg>Pb>Cu,但菌细胞对Cu的吸附能力最高.NH₄⁺的加入对吸附Pb²⁺有促进作用,而K⁺、Na⁺、Ca²⁺和Mg²⁺共存离子的加入会对吸附过程有明显的抑制.当加入DA17.5mmol/L,pH为9.5时,Pb²⁺和菌细胞的去除率分别能够达到93%和96%,经无水Na₂CO3的₃次吸附、浮选和解吸处理后,它们的去除率仍然能够达到94%和97%.动电位和红外光谱分析结果表明,沟戈登氏菌的自然等电点为3.50,吸附Pb2+后增为4.02,与DA作用后降至3.02,吸附过程与细胞壁上的羧酸基团和乙酰胺基团有关,浮选过程则是有静电力、氢键、离子交换和化学络合等过程的协同作用.扫描电镜观察显示,吸附Hg²⁺后,菌细胞表明粘附有絮状物,菌体形状变得不规则.     

纳米活性氧化铝负载磁性纳米零价铁对不同重金属的吸附机理

采用液相还原法将纳米零价铁（nZVI）均匀负载在纳米活性氧化铝（γ-Al₂O₃）表面和孔道内壁上,制备出磁性纳米零价铁/活性氧化铝复合材料（nZVI/γ-Al₂O₃）并对其进行了表征,模拟了5种典型重金属离子Zn（Ⅱ）、Cu（Ⅱ）、Cd（Ⅱ）、Cr（Ⅲ）、Mn（Ⅱ）在nZVI/γ-Al₂O₃上的吸附等温线和动力学,并研究了多元重金属离子体系中竞争吸附和协同吸附行为.结果表明,磁性纳米零价铁负载在纳米活性氧化铝上,不仅克服了因体积效应和表面界面效应所导致的nZVI颗粒团聚,而且使nZVI仍处于稳定的高表面能状态.nZVI/γ-Al₂O₃复合材料兼具高表面积、高还原性和高表面活性,其对Zn（Ⅱ）、Cu（Ⅱ）、Cd（Ⅱ）、Cr（Ⅲ）、Mn（Ⅱ）离子表现出了良好的吸附性能,单一重金属离子的饱和吸附容量分别为53.0、74.9、114.7、99.1、42.9 mg·g^-1.在多元重金属离子体系中5种重金属离子存在竞争吸附和协同吸附作用.当pH为6.67,吸附剂投加量为0.5 g·L^-1,各重金属离子初始浓度为10 mg·L^-1时,300 min内Cr（Ⅲ）、Cu（Ⅱ）、Zn（Ⅱ）、Mn（Ⅱ）的去除率分别高达99.9%、99.9%、99.9%、81.7%,处理后Cr（Ⅲ）、Cu（Ⅱ）、Zn（Ⅱ）平衡浓度均低于检出限,Mn（Ⅱ）和Cd（Ⅱ）平衡浓度分别为1.9 mg·L^-1和6.4 mg·L^-1;在多元体系下Zn（Ⅱ）与其他金属离子存在协同吸附,但Cd（Ⅱ）与其他重金属离子存在竞争吸附,其去除率仅为37.7%.因此,nZVI/γ-Al₂O₃复合吸附材料用于去除废水中典型重金属具有良好的应用前景.     

纳米Fe3O4负载的浮游球衣菌去除Cr(Ⅵ)的研究

以纳米Fe₃O₄负载浮游球衣菌（Sphaerotilus natans）为复合生物吸附剂,考察了其对Cr(Ⅵ)的吸附性能,并对生物吸附机理进行了初步研究.结果表明,pH值是影响复合生物吸附剂吸附Cr(Ⅵ)的主要因素,吸附的最佳pH为2～3;用此复合生物吸附剂对Cr(Ⅵ)进行吸附,其单位吸附量为0.0217 mmol/g.用HCl对其进行再生,再生率在90％以上;—CONH₂和—NH—是菌体吸附Cr(Ⅵ)的主要活性基团,静电吸引是复合生物吸附剂吸附Cr(Ⅵ)的主要机理之一.     

响应曲面法优化KOH改性污泥生物炭的制备及其强化去除Pb（Ⅱ）的研究

采用响应曲面法优化了KOH改性污泥生物炭（SB-KOH）的制备条件,研究了各因素之间对生物炭吸附性能的交互影响,并且探讨了KOH强化生物炭吸附能力的机制.同时,研究了吸附时间、吸附温度及pH对SB-KOH吸附Pb（Ⅱ）的影响,探讨其吸附机理.结果表明：KOH浸渍浓度是最显著因素,较高浸渍浓度有利于提高SB-KOH的吸附性能;增加KOH浸渍浓度和升高热解温度可以协同提高SB-KOH的吸附性能;最佳制备条件为2.5 mol·L^-1的KOH浸渍浓度、7 h的浸渍时间、631 ℃的热解温度和44 min的热解时间.KOH改性后的污泥生物炭表面粗糙, 比表面积增大,微孔数量增加,SB-KOH的比表面积为141.22 m²·g^-1,是原污泥生物炭（SB,5.93 m²·g^-1）的24倍,改性后的生物炭碱性提高、K元素含量增加.SB-KOH吸附Pb（Ⅱ）是以化学吸附为主的多分子层混合吸附,膜扩散是主要的速率控制步骤,增加溶液pH、提高温度可促进吸附.吸附机制涉及矿物沉淀（Q_mp）、离子交换（Q_ie）、含氧官能团的络合（Q_oc）和金属π键结合（Q_mπ）,不同吸附机理的贡献顺序为：Q_mp（143.5 mg·g^-1）>Q_ie（39.67 mg·g^-1）>Q_oc（8.56 mg·g^-1）>Q_mπ （1.65 mg·g^-1）,KOH改性强化了生物炭对Pb（Ⅱ）的矿物沉淀和离子交换吸附量.本研究丰富了KOH改性污泥生物炭的制备理论,阐明了SB-KOH吸附Pb（Ⅱ）吸附机理及其影响的主要机制.     

Pb(NO3)2与CPC共存对沉积物吸附对硝基苯酚的影响

选取Pb(NO₃)₂、氯化十六烷基吡啶(CPC)、对硝基苯酚为代表污染物,试验了重金属与表面活性剂共存对有机物在沉积物上吸附行为的影响.结果表明:Pb(NO₃)₂的存在减弱了CPC的增强吸附效应,Pb(NO₃)₂和CPC共存对对硝基苯酚的吸附产生拮抗效应.在固定CPC初始浓度不变的情况下,拮抗效应随Pb(NO₃)₂初始浓度增大而加强.同时,拮抗效应也取决于CPC的浓度.当CPC初始浓度小于3 000mg/L(平衡浓度低于临界胶束浓度CMC)时,这种拮抗效应尤为明显;随着表面活性剂浓度的继续增加,拮抗效应减弱,并逐渐趋向于CPC的独立效应.机理探讨表明,共存体系中,Pb²⁺与CPC在同一吸附点位不存在竞争吸附.     

PM10中重金属的分布及其在模拟酸雨中的释放

运用扫描电镜-X射线能谱分析方法(SEM-EDS)和电感耦合等离子体-原子发射光谱法(ICP-AES),分析和测定了佛山市可吸入颗粒物(PM₁₀)及其中重金属的赋存状态和质量分布.同时研究了模拟酸雨淋溶条件下PM₁₀中重金属Cu、Pb、Zn和Cd的释放过程.结果表明,颗粒物在大气中存在的形态各异,主要以簇状集合体形式存在.PM₁₀日平均浓度为0.19 mg/m³,与国家二级标准(0.15 mg/m³)相比,超标率为79%.PM₁₀中含有一定量的Zn、Pb、Cu和Cd,其中Zn、Pb的含量要高于Cd和Cu.模拟酸雨淋溶实验显示,PM₁₀中Cu、Pb、Zn、Cd均有不同程度的释放,Cd和Zn的释放率明显高于Cu和Pb,且释放速率较快;pH值是影响4种重金属释放的主要因素,随模拟淋溶液pH值降低,重金属的释放强度显著提高.     

用EXAFS研究Zn在水锰矿上的吸附-解吸机理

用延展X光吸收精细结构光谱(EXAFS)研究了重金属Zn(Ⅱ)在水锰矿(γ-MnOOH)上吸附产物的微观结构及其吸附机理.结果表明,Zn(Ⅱ)-水锰矿体系中(pH 7.5,0.1mol/LNaNO₃介质,25℃),Zn²⁺主要是通过共用水合Zn²⁺的O原子及水锰矿表面上的O原子形成Zn-O键,从而结合到水锰矿固体表面上的.平均Zn-O原子间距为1.998±0.010 A(n=3).这个Zn-O键键长是六配位的Zn(H₂O)²⁺₆及其水解产物四配位的Zn(OH)₂或Zn(OH)₄^2-各以一定比例混合吸附于水锰矿表面而形成的.同时,对第二配位层(Zn-Mn相互作用)的EXAFS图谱分析证明存在2个典型的Zn-Mn原子间距,即R₁=3.08±0.024A(n=3)和R2=3.54±0.018 A(n=3).这2个Zn-Mn原子距分别对应于水锰矿结构单元MnO6八面体与Zn水合离子ZnO多面体结合的2种方式,即共用2个O原子的边-边结合与共用1个O原子的角-角结合.边-边结合是较强的吸附位,Zn-Mn原子距较短(R₁=3.08A),吸附较不可逆.角-角结合是较弱的吸附位,Zn-Mn原子距较长(R₂=3.54A),吸附较为可逆.这一结果从微观上证明了亚稳平衡态吸附理论(MEA理论)的基本假设,即具有相同吸附密度的同一吸附质由于吸附力强弱以及微观构型的不同可具有不同的化学位,因而证明了修正传统吸附热力学的基本假设(吸附密度为热力学状态函数)的必要性.宏观的吸附-解吸热力学实验表明Zn(Ⅱ)在水锰矿上的吸附是不可逆的,EXAFS结果指出这种不可逆性主要是由Zn水合离子中ZnO多面体与水锰矿结构单元MnO₆八面体之间的边-边结合所导致的.     

鸟粪石法回收养猪废水中磷时pH对沉淀物组分的影响

采用鸟粪石沉淀法对养猪废水中的磷进行回收,应用红外光谱和X射线衍射法,并结合物料衡算研究pH变化对沉淀物组分的影响.结果表明,当pH由8.0升至9.0时,磷去除率从85%增加到94%;pH在9.0～11.0范围,磷去除率稳定在94%左右;当pH升高至12.0,磷去除率急剧下降至70％.沉淀物组分为鸟粪石(MgNH₄PO₄·6H₂O)、 钾型鸟粪石(MgKPO₄·6H₂O)、 Ca₃(PO₄)₂·xH₂O和Mg(OH)₂,不含有硫酸盐和碳酸盐.当pH<9.0,沉淀物组分主要为鸟粪石;pH在9.0～10.0范围时,鸟粪石含量降低,钾型鸟粪石、 Ca₃(PO₄)₂·xH₂O含量呈逐渐增加趋势;pH由10.0升至12.0时,鸟粪石含量急剧下降,Ca₃(PO₄)₂·xH₂O和Mg(OH)₂含量快速增加,而钾型鸟粪石快速增加并在pH 11.0达到最大后急剧下降.因此,回收养猪废水中的磷时要获得纯度高的鸟粪石产品,pH值应控制在8.0～9.0.     

纳米Fe3O4负载的浮游球衣菌去除重金属离子的工艺研究

以纳米Fe₃O₄负载浮游球衣菌（Sphaerotilus natans）制备复合生物吸附剂,对此吸附剂进行表征并考察了其吸附水中重金属离子的性能.红外光谱分析表明,此复合生物吸附剂表面的主要活性基团为酰胺基（—CONH—）和羟基（—OH）.吸附性能研究表明,菌含量和流量是影响复合生物吸附剂吸附重金属离子的主要因素,在Cu²⁺初始浓度c₀<20 mg/L,菌含量1.5 g/L（菌/ Fe₃O₄＝3∶2）,流量0.96 L/h 时吸附剂对Cu²⁺的吸附效果最好;用稀盐酸对复合生物吸附剂进行再生,吸附剂可重复使用10次以上,再生液可重复使用3次; 吸附选择性为：Pb²⁺ > Cu²⁺ > Zn²⁺>Cd²⁺.     

EXAFS研究Zn在δ-MnO2上的吸附-解吸机理

用延展X-ray吸收精细结构光谱(EXAFS)研究了重金属Zn(Ⅱ)在δ-MnO₂上吸附产物的微观结构及其吸附机制.在pH 5.50,0.1mol/L NaNO₃介质中,吸附在δ-MnO₂表面上Zn(Ⅱ)以六配位的水合离子八面体形式存在.水合锌离子八面体从δ-MnO₂层状结构的空位上下方,与δ-MnO₂的结构单元MnO₆八面体通过共用O原子结合,形成角-角结合的弱吸附,Zn-O平均原子间距为(2.071±0.007)A(n=3),Zn-Mn平均原子间距为(3.528±0.006)A(n=3).在同一条等温线上随着吸附量增加,以角-角结合的弱吸附形式基本上没有变化.宏观的吸附-解吸实验结果显示Zn(Ⅱ)在δ-MnO₂上的吸附可逆性很高,解吸等温线和吸附等温线几乎重合在一起EXAFS结果从分子水平表明,Zn(Ⅱ)在δ-MnO₂上的高吸附可逆性是由角-角形式弱吸附所导致的.     

竞争干扰对轮叶黑藻吸附Pb(Ⅱ)的影响

沉水植物处理低浓度重金属废水是一项清洁和廉价的技术.主要研究了不同初始浓度和pH条件下,轮叶黑藻鲜样在单一、二元和三元金属离子体系中对铅离子的生物吸附特征.在单一金属离子体系中,不同pH值条件下的实验结果表明,pH值在2.0～6.0间变化时,轮叶黑藻对铅的吸附能力随pH值升高而增强,当初始铅浓度为250 mg/L和pH...     

Surface reaction of Bacillus cereus biomass and its biosorption for lead and copper ions

In this study, the surface chemical functional groups of Bacillus cereus biomass were identified by Fourier transform infrared （FTIR） analytical technique. It had been shown that the B. cereus cells mainly contained carboxyl, hydroxyl, phosphate, amino and amide functional groups. The potentiometric titration was conducted to explain the surface acid-base properties of aqueous B. cereus biomass. The computer program FITEQL 4.0 was used to perform the model calculations. The optimization results indicated that three sitesthree pKas model, which assumed the cell surface to have three distinct types of surface organic functional groups based on the IR analysis results, simulated the experimental results very well. Moreover, batch adsorption experiments were performed to investigate biosorption behavior of Cu（Ⅱ） and Pb（Ⅱ） ions onto the biomass. Obviously, the adsorption equilibrium data for the two ions were reasonably described by typical Langmuir isotherm.     

Adsorption characteristics of copper, lead, zinc and cadmium ions by tourmaline

The adsorption characteristics of heavy metals： Cu（Ⅱ）, Pb（Ⅱ）, Zn（Ⅱ） and Cd（Ⅱ） ions on tourmaline were studied. Adsorption equilibrium was established. The adsorption isotherms of all the four metal ions followed well Langmuir equation. Tourmaline was found to remove heavy metal ions efficiently from aqueous solution with selectivity in the order of Pb（Ⅱ）〉Cu（Ⅱ）〉Cd（Ⅱ）〉Zn（Ⅱ）. The adsorption of metal ions by tourmaline increased with the initial concentration of metal ions increasing in the medium. Tourmaline could also increase pH value of metal solution.The maximum heavy metal ions adsorbed by tourmaline was found to be 78.86, 154.08, 67.25, and 66.67 mg/g for Cu（Ⅱ）, Pb（U）, Zn（Ⅱ） and Cd（U）, respectively. The temperature （25-55℃） had a small effect on the adsorption capacity of tourmaline. Competitive adsorption of Cu（Ⅱ）, Pb（Ⅱ）, Zn（Ⅱ） and Cd（Ⅱ） ions was also studied. The adsorption capacity of tourmaline for single metal decreased in the order of Pb〉Cu〉Zn 〉Cd and inhibition dominance observed in two metal systems was Pb〉Cu, Pb〉Zn, Pb〉Cd, Cu〉Zn, Cu〉Cd, and Cd〉Zn.     

Biosorption mechanisms involved in immobilization of soil Pb by Bacillus subtilis DBM in a multimetal-contaminated soil

Mechanisms of soil Pb immobilization by Bacillus subtilis DBM, a bacterial strain isolated from a heavy-metal-contaminated soil, were investigated. Adsorption and desorption experiments with living bacterial cells as well as dead cells revealed that both extracellular adsorption and intracellular accumulation were involved in the Pb2＋removal from the liquid phase. Of the sequestered Pb（II）, 8.5% was held by physical entrapment within the cell wall, 43.3% was held by ion-exchange, 9.7% was complexed with cell surface functional groups or precipitated on the cell surface, and 38.5% was intracellularly accumulated.Complexation of Pb2＋with carboxyl, hydroxyl, carbonyl, amido, and phosphate groups was demonstrated by Fourier transform infrared spectroscopic analysis. Precipitates of Pb5（PO4）3OH, Pb5（PO4）3Cl and Pb10（PO4）6（OH）2that formed on the cell surface during the biosorption process were identified by X-ray diffraction analysis. Transmission electron microscopy–energy dispersive spectroscopic analysis confirmed the presence of the Pb（II）precipitates and that Pb（II） could be sequestered both extracellularly and intracellularly.Incubation with B. subtilis DBM significantly decreased the amount of the weak-acid-soluble Pb fraction in a heavy-metal-contaminated soil, resulting in a reduction in Pb bioavailability, but increased the amount of its organic-matter-bound fraction by 71%. The ability of B.subtilis DBM to reduce the bioavailability of soil Pb makes it potentially useful for bacteria-assisted phytostabilization of multi-heavy-metal-contaminated soil.     

Biosorption of cadmium(II) and lead(II) ions from aqueous solutions onto dried activated sludge

Introduction Toxic metal compounds are frequently used in industrial processes and are widely distributed in the environment. Due to their extended persistence in biological systems and tendency to bioaccumulate as they move up the food chain, they repres…     

Pb(Ⅱ) biosorption using chitosan and chitosan derivatives beads: Equilibrium,ion exchange and mechanism studies

The study examined the adsorption of Pb(II) ions from aqueous solution onto chitosan, chitosan-GLA and chitosan-alginate beads. Several important parameters influencing the adsorption of Pb(II) ions such as initial pH, adsorbent dosage and different initial concentration of Pb(II) ions were evaluated. The mechanism involved during the adsorption process was explored based on ion exchange study and using spectroscopic techniques. The adsorption capacities obtained based on non-linear Langmuir isotherm for ch...     

青霉菌和镰刀菌对重金属Cd~(2+)、Cu~(2+)、Zn~(2+)和Pb~(2+)的吸附特性

研究了青霉菌和镰刀菌对重金属Cd2+、Cu2+、Zn2+和Pb2+的吸附特性,探讨了复合重金属和不同培养基对菌株吸附能力的影响.同时,采用察氏液体培养基(CDM)和马铃薯葡萄糖培养基(PDB)接种菌株,对不同种类和浓度的重金属进行吸附实验.结果表明,青霉菌和镰刀菌对Cd2+、Cu2+和Zn2+的吸附率随金属浓度的升高而下降,吸附量随金属浓度的增加先增大后减小;当浓度增加到较高值(300mg·L-1)时,Pb2+的吸附率开始下降,吸附量先逐渐增加后变化不大.菌丝体对重金属的吸附能力表现出一定的差异性,对Pb2+的吸附率和吸附量明显高于其他3种金属,CDM培养青霉菌对300mg·L-1Pb2+的最大吸附量达到34.80mg·g-1.多种重金属的复合抑制了菌丝体对重金属离子的吸附.不同菌丝体对复合重金属的吸附量差异性较大,PDB培养混合菌体对重金属离子的吸附率和吸附量均较大,并有明显的促进作用.CDM培养菌丝体对Pb2+的吸附量均高于PDB培养菌丝体.     

Pb（II） biosorption using chitosan and chitosan derivatives beads： Equilibrium, ion exchange and mechanism studies

The study examined the adsorption of Pb(II) ions from aqueous solution onto chitosan, chitosan-GLA and chitosan-alginate beads. Several important parameters influencing the adsorption of Pb(II) ions such as initial pH, adsorbent dosage and di erent initial concentration of Pb(II) ions were evaluated. The mechanism involved during the adsorption process was explored based on ion exchange study and using spectroscopic techniques. The adsorption capacities obtained based on non–linear Langmuir isotherm for chitosan, chitosan-GLA and chitosan-alginate beads in single metal system were 34.98, 14.24 and 60.27 mg/g, respectively. However, the adsorption capacity of Pb(II) ions were reduced in the binary metal system due to the competitive adsorption between Pb(II) and Cu(II) ions. Based on the ion exchange study, the release of Ca2+, Mg2+, K+ and Na+ ions played an important role in the adsorption of Pb(II) ions by all three adsorbents but only at lower concentrations of Pb(II) ions. Infrared spectra showed that the binding between Pb(II) ions and the adsorbents involved mostly the nitrogen and oxygen atoms. All three adsorbents showed satisfactory adsorption capacities and can be considered as an e cient adsorbent for the removal of Pb(II) ions from aqueous solutions.     

海洋赤潮生物原甲藻对重金属的富集机理

为了探讨海洋赤潮生物原甲藻及其藻壁多糖的重金属富集机理,用赤潮生物海洋原甲藻Prorocentrum micans活藻体和甲醛杀死的藻体分别进行重金属离子Cu²⁺、Pb²⁺、Ni²⁺、Zn²⁺、Ag⁺、Cd²⁺的生物吸附实验.重金属生物吸附动力学研究表明,吸附过程可在30min内完成,pH对吸附的影响较大,适宜范围是5.0以上.用热水法提取的藻体多糖对上述6种离子的混合液吸附量约为藻体的5倍,比较藻体与多糖对6种离子的吸附结果可知,藻体对金属离子的吸附主要是藻壁多糖的作用,红外研究表明,-OH和-CONH₂基是吸附的活性中心.机理研究对于利用赤潮生物进行重金属废水处理、赤潮的化学治理以及研究海水中重金属离子的迁移转化规律有重要的意义.     

Adsorptive removal of heavy metal ions from industrial effluents using activated carbon derived from waste coconut buttons

Removal of heavy metal ions from industrial effluents by the activated carbon prepared by steam activation of waste coconut buttons through batch adsorption process.