放射性核素在海洋环境吸附体系中的固体浓度效应
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摘要
通过Ag-110m在海洋沉积物中的静态吸附-解吸实验,系统地研究了放射性核素在海洋环境吸附体系中的固体浓度效应。实验结果表明:Ag-110m在海洋沉积物中的吸附-解吸等温线趋近于线性,且随着固体浓度的升高,等温线呈下降趋势,存在固体浓度效应。解吸等温线比吸附等温线滞后,固体浓度0.1~1.0g·L~(-1)范围内,吸附滞后角(θ)随着固体浓度的增加逐渐增大,不可逆性明显增强,固体浓度改变了吸附体系的不可逆性,符合"亚稳平衡吸附理论"对固体浓度效应产生机制的预测,而固体浓度达到3.0g·L~(-1)后,吸附-解吸等温线几乎重合,体系接近可逆反应。因此对于放射性核素,存在一个区间范围使得吸附体系的不可逆程度随固体浓度的增加而增大,但是超过区间的上、下限值后,体系趋近于可逆反应。应用Freundlich-SCA表面组分活度模型,用活度代替浓度,校正实际与理想吸附体系间的偏离,将不同固体浓度下的吸附-解吸实验数据分别归入同一条吸附等温线和解吸等温线,可以用来预测其他固体浓度下的吸附-解吸平衡状态。
The particle concentration effect of radionuclides in marine environment adsorption system was systematically studied through static adsorption-desorption experiments of Ag-110 m in marine sediments.The experimental results showed that adsorptiondesorption isotherms of Ag-110 m in marine sediments tended to be linear and existed particle concentration effect phenomenon because of the isotherms decreased with the increasing of particle concentration.The desorption isotherm lagged behind the adsorption isotherm and angle between them was called"adsorption hysteresis angle( θ) ". When the particle concentration ranged from 0. 1 g·L~(-1) to 1. 0 g·L~(-1),θwas gradually increased as the concentration of particle increases.That means the particle concentration changed the irreversibility of the adsorption system and irreversibility increased markedly.The results was fully justified the prediction to the mechanism of particle concentration effects using"metastable equilibrium adsorption theory". When the particle concentration reached 3. 0 g·L~(-1),the adsorption-desorption isotherms almost coincided and the system become reversible. For the radionuclides adsorption system,there is an interval so that the degree of irreversibility increase with the increasing of solid concentration,but after exceeding the upper and lower values of that interval the system tend to be reversible.Using activity instead of concentration,the deviates between actual and ideal adsorption system could be corrected,and using Freundlich-SCA surface activity of component model adsorption and desorption experiments data under different solid concentration can be classified as the same adsorption isotherm or desorption isotherms Which can be used to predict the adsorption desorption of other solid concentration under the equilibrium state.
The particle concentration effect of radionuclides in marine environment adsorption system was systematically studied through static adsorption-desorption experiments of Ag-110 m in marine sediments.The experimental results showed that adsorptiondesorption isotherms of Ag-110 m in marine sediments tended to be linear and existed particle concentration effect phenomenon because of the isotherms decreased with the increasing of particle concentration.The desorption isotherm lagged behind the adsorption isotherm and angle between them was called"adsorption hysteresis angle( θ) ". When the particle concentration ranged from 0. 1 g·L~(-1) to 1. 0 g·L~(-1),θwas gradually increased as the concentration of particle increases.That means the particle concentration changed the irreversibility of the adsorption system and irreversibility increased markedly.The results was fully justified the prediction to the mechanism of particle concentration effects using"metastable equilibrium adsorption theory". When the particle concentration reached 3. 0 g·L~(-1),the adsorption-desorption isotherms almost coincided and the system become reversible. For the radionuclides adsorption system,there is an interval so that the degree of irreversibility increase with the increasing of solid concentration,but after exceeding the upper and lower values of that interval the system tend to be reversible.Using activity instead of concentration,the deviates between actual and ideal adsorption system could be corrected,and using Freundlich-SCA surface activity of component model adsorption and desorption experiments data under different solid concentration can be classified as the same adsorption isotherm or desorption isotherms Which can be used to predict the adsorption desorption of other solid concentration under the equilibrium state.
引文
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[21]郭亚利,严锦根,侯万国.吸附剂浓度对Zn(Ⅱ)和Cd(Ⅱ)在高岭土上吸附的影响[J].环境工程学报,2014,8(5):1791-1796.
[22]牟德海,宋海青,闫世平,等.110Agm在大亚湾表层沉积物上的吸附和解吸[J].核化学与放射化学,2005,27(3):158-163.
[2]黄岁樑,李海涛.海河沉积物对邻苯二甲酸二甲酯吸附行为研究[J].环境污染与防治,2007,29(5):321-324.
[3]朱健,吴庆定,王平,等.经典等温吸附模型在重金属离子/硅藻土体系中的应用及存在问题[J].环境科学,2013,34(11):4341-4348.
[4]Helmy A K,Ferreiro E A,Busstti S G.Effect of particle association on 2,2'-bipyridyl adsorption onto kaolinite[J].J Colloid Interface Sci,2000,225(2):398-402.
[5]Chang T W,Wang M K.Assessment of sorbent/water ratio effect on adsorption using dimensional analysis and batch experiments[J].Chemosphere,2002,48(4):419-426.
[6]Pan G,Liss P S J.Metastable-Equilibrium Adsorption Theory[J].J Colloid Interface Sci,1998,201(201):77-85.
[7]潘纲.亚稳平衡态吸附(MEA)理论-传统吸附热力学理论面临的挑战与发展[J].环境科学学报,2003,23(2):156-173.
[8]李静,张美一,潘纲,等.不同吸附模式对As(V)在Ti O2颗粒上亚稳态吸附的影响[J].物理化学学报,2013,29(7):1541-1549.
[9]徐丛,李薇,潘纲.Zn(II)/α-Fe OOH吸附体系的固体浓度效应[J].物理化学学报,2009,25(9):1737-1742.
[10]马子川,潘纲,魏雨,等.亚稳平衡吸附态与亚稳平衡系数关系的热力学研究[J].高等学校化学学报,2005,26(3):476-479.
[11]郑慧,肖新峰.生物质竹炭对水中Cd2+的吸附行为研究[J].化学研究与应用,2015,27(5):754-759.
[12]王晓丽,李士成,黄召亚,等.Th(Ⅳ)在高岭土上的吸附行为研究[J].化学研究与应用,2016,28(5):738-742.
[13]马明广,魏云霞,赵国虎,等.白银斜发沸石的改性及其对氨氮的吸附热力学和动力学[J].化学研究与应用,2013,25(11):1537-1540.
[14]Awual M R,Urata S,Jyo A,et al.Arsenate removal from water by a weak-base anion exchange fibrous adsorbent[J].Water Res,2008,42(3):689.
[15]Vinodhini V,Das N.Packed bed column studies on Cr(VI)removal from tannery wastewater by neem sawdust[J].Desalination,2010,264(1):9-14.
[16]Han R P,Zou L N,Zhao X,et al.Characterization and Properties of Iron-Oxide-Coated Zeolite as Adsorbent for Removal of Copper(II)from Solution in Fixed Bed Column[J].Chem Eng J,2009,149(1):123-131.
[17]赵凌曦,宋淑娥,杜娜,等.一个与吸附剂浓度有关的Langmuir等温式[J].物理化学学报,2012,28(12):2905-2910.
[18]Zhao L X,Hou W G.The effect of sorbent concentration on the partition coefficient of pollutants between aqueous and particulate phases[J].Colloid Surf A,2012,396(7):29-34.
[19]Zhao L X,Song S E,Du N.A sorbent concentration-dependent Freundlich isotherm[J].Colloid Polym Sci,2013,291(3):541-550.
[20]赵凌曦.固-液界面吸附中的吸附剂浓度效应研究[D].济南:山东大学,2013.
[21]郭亚利,严锦根,侯万国.吸附剂浓度对Zn(Ⅱ)和Cd(Ⅱ)在高岭土上吸附的影响[J].环境工程学报,2014,8(5):1791-1796.
[22]牟德海,宋海青,闫世平,等.110Agm在大亚湾表层沉积物上的吸附和解吸[J].核化学与放射化学,2005,27(3):158-163.