Pb(II)、Cu(II)、Cd(II)在黄土上二元竞争吸附特性研究

铅、铜、镉是3种具有代表性的重金属污染物,可用于模拟多重离子复合污染情况。研究了离子浓度、土水比等因素对3种元素在黄土上二元竞争吸附特性的影响。等温吸附模型Langmuir、Freundlich和D-R模型都能在一定程度上解释Pb(II)-Cu(II)、Pb(II)-Cd(II)、Cu(II)-Cd(II)在黄土上的竞争吸附性能。黄土对Pb(II)、Cu(II)、Cd(II)的选择顺序为Pb(II)>Cu(II)>Cd(II)。相比单一吸附,黄土对每种离子的吸附容量均有不同程度的下降。溶液的初始浓度越大,3种离子在单位黄土上的最大吸附量也随之增大,吸附效率随之降低;适当增大土水比可提高离子的去除效率。试验结果为黄土作为防污屏障和污水处理材料提供了依据。     

Mn(Ⅱ)、Cr(Ⅲ)在黄土上共存吸附特性研究

重金属是土体污染中最重要的污染物质之一,土中的重金属污染往往是复合污染的形式。通过一系列室内试验,研究了锰铬重金属共存时在黄土上的吸附特性。在Mn(II)、Cr(III)重金属复合体系中,Mn(II)在黄土上的吸附明显受到抑制,吸附量减小14.6%~46.5%,而Cr(III)在黄土上的吸附基本不受Mn(II)的影响。Mn(II)的吸附能较好地符合Langmuir模型,受Cr(III)的抑制而不能很好地符合Fredunlich、D-R模型,Cr(III)的吸附仍能较好地符合Fredunlich、D–R模型。在p H=5~7酸性条件下Cr(III)促进了Mn(II)在黄土上的吸附,Mn(II)对Cr(III)的吸附稍有抑制;在碱性条件下,Cr(III)基本不受影响能完全被去除,而Mn(II)的吸附受到很大的抑制作用。重金属本身的物理属性比如水解常数大小以及黄土中的矿物成分都对Mn(II)、Cr(III)在黄土上吸附特性发挥了重要作用。     

Mn(II)、Cr(III)在黄土上共存吸附特性研究

重金属是土体污染中最重要的污染物质之一,土中的重金属污染往往是复合污染的形式。通过一系列室内试验,研究了锰铬重金属共存时在黄土上的吸附特性。在Mn(II)、Cr(III)重金属复合体系中,Mn(II)在黄土上的吸附明显受到抑制,吸附量减小14.6%~46.5%,而Cr(III)在黄土上的吸附基本不受Mn(II)的影响。Mn(II)的吸附能较好地符合Langmuir模型,受Cr(III)的抑制而不能很好地符合Fredunlich、D-R模型,Cr(III)的吸附仍能较好地符合Fredunlich、D-R模型。在pH=5~7酸性条件下Cr(III)促进了Mn(II)在黄土上的吸附,Mn(II)对Cr(III)的吸附稍有抑制;在碱性条件下,Cr(III)基本不受影响能完全被去除,而Mn(II)的吸附受到很大的抑制作用。重金属本身的物理属性比如水解常数大小以及黄土中的矿物成分都对Mn(II)、Cr(III)在黄土上吸附特性发挥了重要作用。     

重金属Pb(II)在膨润土上去除特性研究

深入研究成本低廉的膨润土对水溶液中Pb(II)的吸附特性,采用Batch试验方法,分析了土水比、pH、离子强度、反应时间、温度及Pb(II)的初始浓度对Pb(II)在膨润土上吸附性能的影响,并对吸附动力学和吸附平衡试验进行了探讨。Pb(II)在膨润土上去除率与pH、离子强度有很强的依赖性。当pH<7时,膨润土对Pb(II)的吸附主要是离子交换,而当7相似文献   

改性沸石对废水中锰的吸附研究

采用吸附法去除水体中重金属锰,以NaOH对天然沸石改性,对含Mn的水体进行处理,通过单因素实验系统考察了改性沸石用量、吸附时间、初始浓度、温度对吸附效果的影响,研究结果表明在25℃,吸附剂用量为1.0 g,吸附时间120 min,对初始浓度为1.0 mg/L时,锰的去除率可达到99.3%,最大吸附容量达到9.93 mg/g。     

重金属Pb(II)在黏土上吸附特性研究

采用Batch试验研究了黏土对水溶液中Pb(II)的吸附特性,分析了土水比、反应时间、pH和温度对Pb(II)在黏土上吸附性能的影响,并对吸附动力学和吸附平衡试验进行了探讨。试验结果表明,当土水比增加时,吸附量相应降低,去除率却相应提高。黏土对Pb(II)的吸附速度较快,可在120 min内达到吸附平衡。pH0较低时,黏土对Pb(II)的主要吸附机理为离子交换;pH0较高时,黏土对Pb(II)的主要吸附机理为表面络合反应。吸附动力学特性符合伪二级动力学模型,液膜扩散速率显著大于黏土颗粒内扩散速率。Langmuir模型可较好地模拟黏土对Pb(II)等温吸附特性,吸附量可达18.86 mg/g,低温有利于黏土对Pb(II)的吸附。     

黄土-粉土混合土对Pb(Ⅱ)的静平衡和动态吸附特性

竖向防污屏障是防止地下水土污染的主要屏障。天然土是屏障最主要的材料来源。以天然粉土为母土,黄土为添加剂,以重金属Pb(Ⅱ)作为污染物的代表,通过粉土-黄土混合土对Pb(Ⅱ)的静平衡吸附和动态吸附试验研究黄土作为添加剂对天然粉土的改良效果。试验考虑了黄土添加量、溶液pH值、反应时间以及重金属初始浓度等对吸附的影响。结果表明添加黄土可以有效改善天然粉土的吸附效果,混合土对Pb(Ⅱ)的吸附容量随黄土添加量的增加线性增长,添加20%黄土的混合土的吸附容量达天然粉土的2倍;添加黄土可减少混合土对重金属的吸附时间,在相同时间内减少迁移量。通过扫描电镜和XRD等手段揭示了黄土对Pb(Ⅱ)的吸附主要是方解石与Pb(Ⅱ)发生界面沉淀作用生成白铅矿;粉土对Pb(Ⅱ)的吸附主要是长石等矿物棱角处经风化水解形成的-OH基团对Pb(Ⅱ)的阳离子交换作用。黄土由于高方解石含量在对Pb(Ⅱ)的吸附方面表现突出,可以作为一种添加剂加入天然土层中,以增强屏障对重金属的吸附阻滞效果,减少环境污染。     

赤泥改性生物炭修复铅污染土性能研究

土壤的重金属污染是制约社会可持续发展的重要环境难题，在“双碳”背景下，本文通过共热解制备赤泥改性生物炭(RMBC),研究RMBC对铅污染土的理化性质、修复效果和工程特性的影响。结果表明，RMBC可以增加铅污染土的pH值并降低其电导率(EC)值。RMBC的掺量越大pH值越高EC值越小。通过盐酸萃取浸出毒性发现随着RMBC掺入量和修复时间的增加土中Pb(II)浸出浓度越低，7%掺量的RMBC对重金属铅污染土的修复效果最好。此外，RMBC的掺入可以增加土体的密实度在一定程度上提高土的承载能力和抗渗能力。借助微观分析揭示了RMBC的修复机理包括络合作用、离子交换和沉淀反应。赤泥改性生物炭能够有效吸附-固定土中的重金属离子，并改良土体的相关性能，在污染修复和工程应用方面具有潜力。     

As(Ⅴ)在粉质黏土中的吸附特性研究

目前对土中重金属吸附特性的研究多集中在金属阳离子,对As(Ⅴ)等以阴离子基团形式存在的重金属关注较少。研究了As(Ⅴ)在粉质黏土中的吸附,并与常见阳离子Pb(Ⅱ)进行了对比。考虑了土水比、反应时间、溶液浓度、pH和温度对吸附的影响,通过吸附动力学、吸附等温线、吸附热力学模型和微细观测试分析了吸附机制,另外研究了吸附As(Ⅴ)和Pb(Ⅱ)后土的渗透特性。试验结果表明,As(Ⅴ)在粉质黏土上的最大吸附量远低于Pb(Ⅱ);As(Ⅴ)吸附量随溶液浓度增加线性增加;Pb(Ⅱ)吸附量随溶液p H增加而增加,而As(Ⅴ)吸附量在碱性条件下稍有减小。As(Ⅴ)和Pb(Ⅱ)的吸附都符合准二阶动力学模型,都是以化学吸附为主,Pb(Ⅱ)吸附与颗粒内扩散和液膜扩散有关,而颗粒内扩散是As(Ⅴ)吸附的主要控速因素;Langmuir模型对As(Ⅴ)拟合较差,As(Ⅴ)属于中等难吸附;Pb(Ⅱ)的吸附是吸热过程,温度高有利于Pb(Ⅱ)吸附,而As(Ⅴ)的吸附过程放热,吸附量随温度升高而降低。微观测试表明,粉质黏土对As(Ⅴ)和Pb(Ⅱ)的吸附基本发生在晶格以外;吸附Pb(Ⅱ)后土颗粒团聚导致孔隙变大,而吸附As(Ⅴ...     

酸性水钠锰矿对水中Mn(Ⅱ)的吸附和催化氧化特性的研究

采用酸性水钠锰矿对水中Mn(Ⅱ)的吸附和催化氧化性能进行了研究.吸附试验结果表明:酸性水钠锰矿对水中Mn(Ⅱ)的吸附等温线符合Langmuir方程,该吸附是单分子层吸附;动力学实验结果表明,吸附过程更符合Lagergren准二级动力学方程,酸性水钠锰矿对水中Mn(Ⅱ)的吸附饱和吸附量约为146.37mg/g.pH对酸性水钠锰矿对水中Mn(Ⅱ)的吸附的影响较大,随着pH的增加,酸性水钠锰矿对水中Mn(Ⅱ)的吸附量增加;对于初始浓度为10mg/L,体积为100mL的含锰溶液,要达到最大去除效果,酸性水钠锰矿的最适投加量为15mg.氧化实验结果表明:在曝气的条件下,酸性水钠锰矿可以促进水中溶解氧对Mn(Ⅱ)的氧化,最大氧化量为46.79mg/g.pH对酸性水钠锰矿对水中Mn(Ⅱ)的氧化的影响较大,随着pH的增加,酸性水钠锰矿对水中Mn(Ⅱ)的氧化量增加,pH的最佳范围为9~10.     

Mechanism of lead adsorption from aqueous solutions using an adsorbent synthesized from natural condensed tannin

Adsorption is a method for removing lead from wastewater. The adsorption of lead on a new adsorbent synthesized from natural condensed tannin has been investigated using a series of batch adsorption experiments. The study on the adsorption mechanism indicates that the adsorbent performed in aqueous solutions as an ionic exchanger whose end group was sodium ion (Na(+)). One lead (II) ion (Pb(2+)) was adsorbed onto the adsorbent by taking the place of two Na(+) ions. The maximum exchangeable Na(+) present on the adsorbent was measured with the proton titration experiments and it was up to 1.0 mmol x Na(+)g(-1) dry adsorbent. To a significant extent, pH influenced the extraction of lead from aqueous solutions. The lead removal efficiency was up to 71%, 87% and 91% with initial solution pH at 3.0, 3.6 and 4.2, respectively. The Langmuir equation fitted the adsorption isotherm data well. The maximum adsorption capacity of lead calculated was 57.5, 76.9 and 114.9 mg lead g(-1) dry adsorbent at initial solution pH of 3.0, 3.6 and 4.2, respectively. Therefore, the adsorbent does offer favorable characteristics in lead removal from acidic wastewater.     

Removal of mercury(II) from aqueous solutions and chlor-alkali industry wastewater using 2-mercaptobenzimidazole-clay

The 2-mercaptobenzimidazole loaded natural clay was prepared for the removal of Hg(II) from aqueous media. Adsorption of the metal ions from aqueous solution as a function of solution concentration, agitation time, pH, temperature, ionic strength, particle size of the adsorbent and adsorbent dose was studied. The adsorption process follows a pseudo-second-order kinetics. The rate constants as a function of initial concentration and temperature were given. The adsorption of Hg(II) increased with increasing pH and reached a plateau value in the pH range 4.0-8.0. The removal of Hg(II) was found to be >99% at an initial concentration of 50 mg/l. Mercury(II) uptake was found to increase with ionic strength and temperature. Further, the adsorption of Hg(II) increased with increasing adsorbent dose and decrease with adsorbent particle size. Sorption data analysis was carried out using Langmuir and modified Langmuir isotherms for the uptake of metal ion in an initial concentration range of 50-1,000 mg/l. The significance of the two linear relationships obtained by plotting the data according to the conventional Langmuir equation is discussed in terms of the binding energies of the two population sites involved which have a widely differing affinity for Hg(II) ions. Thermodynamic parameters such as changes of free energy, enthalpy, and entropy were calculated to predict the nature of adsorption. It was found that the values of isosteric heat of adsorption were varied with surface loading. The chlor-alkali industry wastewater samples were treated by MBI-clay to demonstrate its efficiency in removing Hg(II) from wastewater.     

Sorption of phosphate from acidic wastewater into three Tunisian type clay soils

The removal of phosphates from acidic wastewater using three types of soil minerals (Soil 1, Soil 2, and Soil 3) with a high content of paligorskite, smectite, and illite, respectively, is studied. The effect of the medium pH value, contact duration, and solid-liquid ratio is considered. The smectite-containing soil possesses the highest sorption capacity with respect to phosphate. The isotherms of phosphate sorption by soils are processed in the Freundlich and Langmuir equation coordinates. It is shown that the fitting of isotherms in the Freundlich equation coordinates results in better correspondence with experimental data. In addition, the adsorption selectivity of ions (PO₄ ^3?, F^?, Cl^?) existing in the waste solution by these soils was studied, and the fluoride is more selective in the acid pH region.     

Kinetics of adsorption of Co(II) removal from water and wastewater by ion exchange resins

The capacity of ion exchange resins, IRN77 and SKN1, for removal of cobalt from aqueous solution has been investigated under different conditions namely initial solution pH, initial metal-ion concentration, and contact time. The equilibrium data obtained in this study have been found to fit both the Langmuir and Freundlich adsorption isotherms. The adsorption of Co(II) on these resins follows first-order reversible kinetics. The film diffusion of Co(II) in these ion exchange resins was shown to be the main rate limiting step. The studies showed that these cation exchange resins can be used as efficient adsorbent material for the removal of Co(II) from aqueous solutions.     

Effect of OH and silanol groups in the removal of dyes from aqueous solution using diatomite

The removal of methylene blue, reactive black (C-NN), and reactive yellow (MI-2RN) from aqueous solution by calcined and raw diatomite at 980 degrees C was studied. These studies demonstrated the importance of the various functional groups on the mechanism of adsorption. The role of pore size distribution in the dye adsorption studies was also investigated. The adsorption isotherms were pH dependent. Henry and Freundlich adsorption isotherms were used to model the adsorption behavior and experimental results for all dyes used exhibited heterogeneous surface binding. The removal of the ionisable functional groups increased the pH(ZPC) value from 5.4 to 7.7, while FTIR, SEM and XRD analysis showed a remarkable decrease of the characteristic Si-OH peaks after calcinations at 980 degrees C. The removal of hydroxyl groups from the surface of diatomite lead to a decrease in the adsorption. It was evident from pH and infrared spectra results that mechanisms of methylene blue and reactive yellow adsorption differed from that of reactive black. Accordingly, adsorption on the external surface by n-pi interaction between the pi system of the RB and the electron lone pairs of the oxygen atoms of siloxane group and columbic attraction between the dye and the surface of calcined diatomite was proposed as a possible adsorption mechanism.