天然核桃壳对废水中Cd~(2+)和Pb~(2+)的吸附热力学研究

采用批处理技术研究了天然核桃壳吸附废水中Cd2+和Pb2+的主要影响因素,如p H值、核桃壳用量和离子初始浓度等因素,并探讨了吸附等温线及吸附热力学。研究表明,天然核桃壳对Cd2+和Pb2+的最大吸附量分别为12.5mg/g和38.02mg/g。天然核桃壳吸附Cd2+的过程对Freundlich方程和Langmuir方程的拟合效果都较好;吸附Pb2+的过程则对Freundlich方程的拟合效果要好于Langmuir方程。热力学分析表明,天然核桃壳对Cd2+和Pb2+的吸附属自发吸热过程,且较易发生。     

改性玉米芯对Pb~(2+)、Cu~(2+)的吸附动力学和热力学的实验研究

用酒石酸改性玉米芯,利用改性玉米芯吸附水中的Cu2+和Pb2+。实验结果表明:吸附过程更加能够符合准二级动力学方程,且随温度的升高,吸附越容易进行,吸附过程表观活化能较小,说明该过程具有物理吸附的属性。吸附规律能够更好地用Freundlich方程所描述,且ΔG0,ΔH0,ΔS0,说明吸附是自发、吸热、熵增的过程,温度的升高有利于吸附反应的进行。再生实验结果表明玉米芯再生性能良好。本实验对于重金属的去除具有一定的参考价值。     

土液比对Pb~(2+)的吸附动力学影响研究

探明Pb2+吸附动力学过程,是分析污灌区土壤Pb2+截留能力的理论基础。基于600 mg/L的Pb2+溶液和马鞍山高龙背粉沙质壤土,开展不同土液比条件下的Pb2+吸附动力学试验。结果表明,与常规吸附动力学试验相比,同一土液比情况下的吸附动力学曲线波动性较大,首次波动幅度随土液比的减小逐渐增大,从波动开始到基本稳定所需的时间随土液比的减小逐渐增加,吸附量随着土液比的减小逐渐增大,吸附率却逐渐减小。     

天然硅藻土吸附废水中Cd2+和Pb2+的热力学研究

用天然硅藻土吸附废水中Cd2和Pb2+两种重金属离子,探讨了天然硅藻土对Cd2+和pb2+的吸附等温式和吸附热力学规律.结果表明:天然硅藻土对Cd2+和pb2+的平衡吸附量随温度的升高而增加.两种重金属离子的吸附等温式都与Langmuir方程符合更好.由热力学参数可知吸附过程是自发、吸热的过程.     

改性细菌纤维素硫酸酯对Pb(Ⅱ)吸附性能的影响

以廉价且资源丰富的细菌纤维素为原料,研究制备了改性细菌纤维素硫酸酯吸附材料,并对其进行表征分析。以典型重金属污染物Pb(Ⅱ)为去除目标,考察了不同反应时间、溶液p H和反应温度等对改性细菌纤维素吸附Pb(Ⅱ)的影响。结果表明:经改性后细菌纤维素的吸附性能有所增加;其对Pb(Ⅱ)的平衡吸附量随p H的增大而增加,随温度的增加而减小;吸附过程符合拟二级反应方程和Langmuir吸附等温方程。     

Pb2+在天然泥炭上的吸附特征研究

研究了泥炭吸附水中Pb2 的吸附动力学和吸附等温式.考查了泥炭用量、Pb2 初始浓度、溶液pH值和温度对吸附反应的影响.结果表明,泥炭对Pb2 具有较强的吸附性能;其吸附动力学符合Langmuir准二级反应速率模型;其吸附等温式符合Langmuir和Freundlich等温吸附模型,且其吸附过程为热力学吸热和自发过程.     

磷酸改性板蓝根药渣污泥基生物炭的制备及其对含铅废水的处理研究

铅[Pb(Ⅱ)]对水资源的污染越来越严重,寻找高效、低成本的吸附剂一直是一个难题。选用污泥和板蓝根药渣这两种固体废物使用共热解的方式制备了生物炭,为了增强对废水中铅离子的吸附,用磷酸(H₃PO₄)对生物炭进行了改性处理。通过SEM图像可以看出改性生物炭的孔隙结构变得更加发达,比表面积增大。EDS谱图的结果表明改性生物炭在废水中吸附Pb(Ⅱ)的过程可能存在阳离子交换作用。FTIR、XRD和XPS图像分析显示改性生物炭在废水中吸附Pb(Ⅱ)的过程可能存在络合作用和共沉淀作用。吸附动力学试验结果显示,拟一级动力学模型,拟二级动力学模型和Elovich模型的R²均大于0.99,表明物理和化学吸附在改性生物炭去除Pb(Ⅱ)的过程中都起着重要作用。吸附等温线分析表明,吸附容量n大于1,证实改性生物炭对Pb(Ⅱ)具有良好的吸附效果。由此可见,对环境友好的磷酸改性板蓝根药渣污泥基生物炭可以作为一种有效的吸附剂从水系统中去除Pb(Ⅱ)。     

Pb2+、Cu2+在黄颡鱼性腺中的富集及其对性腺发育的胁迫

研究Pb2+、Cu2+在其不同质量浓度(0.10 mg/L、0.25 mg/L、0.50 mg/L)情况下在黄颡鱼性腺中的富集特性以及对性腺发育的影响。结果表明,黄颡鱼性腺(卵巢)对Pb2+、Cu2+有较强的富集能力,在暴露期间的20—30 d内,Pb2+、Cu2+在性腺内的富集量分别与时间呈线性关系,之后呈对数关系。其中,Cu2+的富集显著大于Pb2+(P<0.01);性腺中的重金属富集与水溶液中Pb2+、Cu2+的浓度相关(P<0.01),具有明显的时间效应和剂量效应。黄颡鱼性腺细胞的发育水平,亦与溶液Pb2+、Cu2+的浓度与暴露时间相关。     

改性玉米芯吸附水中重金属离子的实验研究

以玉米芯做原料,用酒石酸改性,利用改性玉米芯吸附水中的Cu2＋ 和Pb2＋实验结果表明,实验中改性玉米芯吸附水中的Cu2＋ 和Pb2＋的吸附条件为：pH为5,吸附时间为120min,初始浓度为50mg／L,投加量为0．5g,在此条件下,改性玉米芯对Cu2＋ 和Pb2＋的吸附去除率分别为68％和94％,普通玉米芯对Cu2＋和 Pb2＋的吸附去除率分别为25％和65％。吸附过程更加能够符合准二级动力学方程,吸附规律能够更好地用Freundlieh方程所描述。改性玉米芯对重金属离子有选择吸附的能力,Pb2＋更加容易被吸附。本实验对于重金属的去除具有一定的参考价值。     

纳米零价铁/活性炭复合材料去除水中六氯苯的影响因素研究

本文主要研究纳米零价铁/活性炭材料对水中六氯苯(HCB)的去除能力和影响因素。吸附等温研究结果表明该材料对六氯苯的去除符合Langmuir吸附即化学吸附机理。对水中六氯苯和脱氯产物的分析证明纳米零价铁/活性炭对六氯苯的去除包括吸附和脱氯。溶液p H,水中常见阴阳离子的存在等因素都会影响六氯苯去除。低p H对去除有利,这主要是由于低p H对纳米零价铁的氧化过程有利,导致脱氯反应加快。低浓度的HCO-3、Cl-和SO42-能促进六氯苯的去除。这些离子在低浓度时能加快零价铁的腐蚀,对六氯苯的去除有利。而高浓度时则由于铁氧化物沉积会产生抑制作用。NO-3则与六氯苯发生竞争反应,导致六氯苯的去除随硝酸盐的浓度增加而降低。常见的阳离子如Mg2+对六氯苯的去除没有影响。Cu2+和Fe2+的存在不仅改变了溶液的p H,还对纳米零价铁的氧化还原特性有影响。但总体而言,Cu2+和Fe2+的存在对六氯苯的去除是有利的。     

螺旋藻对铅的耐受力初步研究

初步研究了螺旋藻对水溶液中Pb2+的耐受性。实验结果表明:Pb2+对螺旋藻的生长具有抑制作用,随着Pb2+浓度的增加,螺旋藻生长受到的抑制作用也越强;螺旋藻对Pb2+具有一定的耐受性;Pb2+对螺旋藻的72hEC50为11 46mg/L;同时发现螺旋藻藻液pH值随着培养时间的增长而增大。     

Enhancement of removal efficiency of heavy metal ions by polyaniline deposition on electrospun polyacrylonitrile membranes

This paper describes the preparation of a membrane of polyacrylonitrile(PAN) and its corresponding membrane coated with polyaniline(PANI) for the adsorption of heavy metal ions.Scanning electron microscopy micrographs revealed that all the membranes exhibited nanofibrous morphology.The prepared membranes were characterized by Fourier transform infrared spectroscopy(FTIR).The prepared membranes were used as an adsorbent for hazardous heavy metal ions Pb~(2+) and Cr_2 O_7~(2-).The adsorption capacity and the removal efficiency of the membranes were examined as function of the initial adsorbate concentration and pH of the medium.Coated membranes with PANI showed better adsorption performance and their direct current(DC) conductivities were correlated to heavy metal ion concentrations.Adsorption isotherms were also performed,and the adsorption process was tested according to the Langmuir and Freundlich models.The regeneration and reuse of the prepared membranes to re-adsorb heavy metal ions were also investigated.The enhancement in adsorption performance and reusability of PANI-coated membranes in comparison with non-coated ones is fully discussed.The results show that the maximum adsorption capacities of lead and chromate ions on the PANI-coated membranes are 290.12 and 1 202.53 mg/g,respectively.     

Equilibrium, kinetic and thermodynamic studies of mercury adsorption on almond shell

The application of almond shell as a low cost natural adsorbent to remove Hg(2+) from aqueous solution was investigated. Batch experiments were carried out to evaluate the adsorption capacity of the material. The chemical and physical parameters such as pH, sorbent amount, initial ion concentration, and contact time were optimized for the maximum uptake of mercury onto the solid surface. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models, and the experimental data were found to fit the Langmuir model rather than the Freundlich. The maximum adsorption capacity obtained from the Langmuir isotherm was 135.13 mg/g. A kinetic study was carried out with pseudo-first-order and pseudo-second-order reaction equations and it was found that the Hg(2+) uptake process followed the pseudo-second-order rate expression. The thermodynamic values, ΔG(0), ΔH(0) and ΔS(0), indicated that adsorption was an endothermic and spontaneous process. The potential of this material for mercury elimination was demonstrated by efficient Hg(2+) removal from a synthetic effluent.     

Modification of granular activated carbon using low molecular weight polymer for enhanced removal of Cu(2+) from aqueous solution.

Palm shell activated carbon was modified via surface impregnation with polyethyleneimine (PEI) to enhance removal of Cu(2+) from aqueous solution in this study. The effect of PEI modification on batch adsorption of Cu(2+) as well as the equilibrium behavior of adsorption of metal ions on activated carbon were investigated. PEI modification clearly increased the Cu(2+) adsorption capacities by 68% and 75.86% for initial solution pH of 3 and 5 respectively. The adsorption data of Cu(2+) on both virgin and PEI-modified AC for both initial solution pH of 3 and 5 fitted the Langmuir and Redlich-Peterson isotherms considerably better than the Freundlich isotherm.     

Biosorption of heavy metals onto nonliving Laminaria japonica

In this paper, study of the biosorption of Cd(2+) and Pb(2+) by nonliving Laminaria japonica in a batch adsorption system is described. The content of acidic sites and the dissociation constant of carboxylic acid functional groups (metal-binding site) of L. japonica were experimentally determined by conductometric and potentiometric titrations and theoretically predicated by using monodentate and bidentate binding models. The models are based on the monodentate or bidentate binding reactions of bivalent metal ions to acidic sites. The acidic site content and carboxylic acid dissociation constants determined are 1.25 and 0.18 mmol L(-1), respectively. The results showed that the bidentate adsorption model fits well the biosorption of bivalent metal ions onto L. japonica with the bidentate binding constants for Cd(2+) and Pb(2+) being 5.72 × 10(3) and 6.24 × 10(4) L mol(-1), respectively. The adsorption process of L. japonica followed the pseudo-second-order kinetics.     

The sorption of lead, cadmium, copper and zinc ions from aqueous solutions on a raw diatomite from Algeria

The adsorption of Cu(2+), Zn(2+), Cd(2+) and Pb(2+) ions from aqueous solution by Algerian raw diatomite was studied. The influences of different sorption parameters such as contact pH solution, contact time and initial metal ions concentration were studied to optimize the reaction conditions. The metals ions adsorption was strictly pH dependent. The maximum adsorption capacities towards Cu(2+), Zn(2+), Cd(2+) and Pb(2+) were 0.319, 0.311, 0.18 and 0.096 mmol g(-1), respectively. The kinetic data were modelled using the pseudo-first-order and pseudo-second-order kinetic equations. Among the kinetic models studied, the pseudo-second-order equation was the best applicable model to describe the sorption process. Equilibrium isotherm data were analysed using the Langmuir and the Freundlich isotherms; the results showed that the adsorption equilibrium was well described by both model isotherms. The negative value of free energy change ΔG indicates feasible and spontaneous adsorption of four metal ions on raw diatomite. According to these results, the high exchange capacities of different metal ions at high and low concentration levels, and given the low cost of the investigated adsorbent in this work, Algerian diatomite was considered to be an excellent adsorbent.     

水溶液体系中高岭石吸附Cu2+的研究

研究了溶液浓度、pH值、交换吸附时间、磁感应强度和磁场处理时间对高岭石吸附重金属离子Cu2+的影响作用。实验结果及分析表明,影响高岭石对Cu2+吸附的因素有:①在一定条件下,增加吸附作用时间,吸附量随之缓慢递增,最佳吸附时间是40~50 min;②改变溶液中初始浓度,其吸附交换等温线呈S形,属于二级吸附;③溶液的pH值在2~5之间增加时,吸附量也随之直线增加。指出磁场作用对低浓度的Cu2+的吸附量有着显著的影响,主要因素有磁场强度、磁化时间和磁化对象。     

Fenton-活性炭法处理炮弹销毁废水的实验研究

针对炮弹销毁废水TNT、CODCr及色度含量高、水质稳定、难以降解的特点,在实验室试验的基础上,采用Fenton氧化-活性炭吸附的集成技术,进行了现场的实验研究,重点分析研究了影响Fenton氧化效果的主要因素,确定了最佳的运行参数,即c(H2O2)=0.05 mol/L,c(Fe2+)=1.80 mmol/L,pH=3.5,反应时间t=12 h。实际生产运行表明,经Fenton氧化后,TNT可有效去除80%,CODC r去除率为84%,经活性炭吸附后TNT<1 mg/L,CODC r<50 mg/L,出水水质稳定,完全达到冷却水回用标准,实现了污水的零排放。     

Heavy metal adsorption changes of EAF steel slag after phosphorus adsorption

A kind of electric arc furnace (EAF) steel slag was phosphated, and its isothermal and dynamic adsorptions of copper, cadmium, and lead ions were measured to determine if heavy metal adsorption changes after phosphorus adsorption. The surface area increased greatly after the slag was phosphated. Isothermal adsorption experiments showed that the theoretical Q(max) of the EAF steel slag on Cu(2+), Cd(2+), and Pb(2+) improved 59, 50, and 89% respectively after it was phosphated. Dynamic adsorption results showed that the greatest adsorption capacities of unit volume of Cu(2+), Cd(2+), and Pb(2+) were 2.2, 1.8, and 1.8 times that of the column packed with original EAF steel slag when the column was packed with phosphate EAF steel slag at the same heavy metal ion concentration. The breakthrough time, the exhaustion time and elution efficiency of the column also increased when the column was packed with phosphated EAF steel slag compared with that packed with original EAF steel slag. Phosphorus adsorption could further improve the heavy metal ion adsorption of the EAF steel slag.     

Simultaneous copper ion removal and hydrogen production from water over a TiO? nanotube photocatalyst

A one-dimensional (1-D) mesoporous TiO? nanotube (TiNT) was successfully synthesized via a hydrothermal-calcination process, and employed in simultaneous photocatalytic Cu(2+) removal and H? production. Under irradiation, Cu(2+) in the wide concentration range of 8-800 ppm, could be reduced rapidly, and the reduction was not severely impacted by co-existing inorganic ions in solution. Simultaneous with Cu(2+) reduction, noticeable H? was produced over the in-situ fabricated Cu incorporated TiNT (Cu-TiNT) photocatalyst, while H? evolution rate was controlled by the Cu(2+) reduction process, due to competition of electron capture between protons and Cu(2+). In addition, H? generation activity of Cu-TiNT depended on the initial Cu(2+)/Ti ratio, and could be depressed by co-existing ions in solution. Fast Cu(2+) reduction and remarkable H? evolution confirmed the feasibility of simultaneous Cu(2+) removal and H? production over a TiNT photocatalyst.