土壤及组分对重金属镉的吸附解吸机理研究

发布时间：2018-03-27 17:24

本文选题：土壤　切入点：粘粒　出处：《吉林农业大学》2015年硕士论文

【摘要】：应用平衡吸附试验法,研究了不同Cd2+浓度、不同pH值环境、添加不同浓度外源干扰Fe3+、Al3+条件下,对黑土、粘粒及粘粒级复合体对重金属镉(Cd)的吸附解吸试验.结果表明:(1)随着重金属Cd2+平衡浓度的增加,供试土壤对Cd2+的吸附量也伴随增加,具体表现为粘粒级复合体原土粘粒。吸附量的大小与供试土样的比表面积,单位质量内所含的有机质,粘土矿物及金属氧化物含量成正相关,有利于重金属镉的吸附。(2)通过对数据进行Langmuir方程和Freundlich方程拟合,原土、粘粒级复合体、粘粒对Cd2+的吸附等温线可通过Freundlich方程进行很好地描述而Langmuir方程则不适宜对Cd2+吸附等温线的描述。(3)加入外源干扰离子Fe3+后,原土、土壤粘粒、粘粒级复合体对Cd2+的吸附量随着Fe3+浓度的升高而降低,吸附量顺序的具体表现为原土粘粒级复合体粘粒。(4)加入外源干扰离子Al3+后,原土、土壤粘粒、粘粒级复合体对Cd2+的吸附量随Al3+浓度的增高亦有降低趋势。吸附量顺序的具体表现为粘粒级复合体粘粒原土。(5)在pH为9时,原土、粘粒、粘粒级复合体的吸附量达到最大值,具体表现为:原土粘粒级复合体粘粒。在解吸试验中,原土、粘粒、粘粒级复合体均会随着pH的升高而降低,具体表现为:粘粒级复合体粘粒原土。并且三种供试土壤均在pH为5时达到最大解吸量。pH可通过影响重金属Cd2+的水解、Cd2+与H+的交换作用、供试土壤的吸附表面类型及吸附表面电荷,吸附解吸竞争体系中镉分配系数等方面,对重金属镉离子的吸附产生影响。
[Abstract]:The equilibrium adsorption test was used to study the effects of different concentrations of Cd2 and pH on black soil under the condition of adding different concentrations of exogenous interference of Fe3 and Al3 to black soil. The adsorption and desorption of heavy metal CD ~ (2 +) by clay and clay grade complexes were studied. The results showed that the adsorption amount of Cd2 in the soil increased with the increase of Cd2 equilibrium concentration of heavy metal, and the adsorption of CD _ (2 +) on CD _ (2 +) was also increased with the increase of Cd2 equilibrium concentration. The adsorption amount is positively correlated with the specific surface area of the soil sample, the organic matter, clay mineral and metal oxide content in the sample per unit mass. The data were fitted by Langmuir equation and Freundlich equation. The adsorption isotherms of Cd2 on clay particles can be described by Freundlich equation, but Langmuir equation is not suitable for describing Cd2 adsorption isotherms. The adsorption amount of Cd2 on clay complex decreased with the increase of Fe3 concentration, and the order of adsorption capacity was that the original soil and soil clay particles were added with exogenous interference ion Al3, and the order of adsorption capacity was that the original soil and soil clay particles were added with the addition of external interfering ion Al3. The amount of Cd2 adsorbed by clay grain-grade complex also decreased with the increase of Al3 concentration. The order of adsorption capacity was that the adsorption capacity of clay grain-grade complex reached the maximum at pH 9, and the adsorption capacity of clay, clay and clay grade complex reached the maximum. In the desorption test, the clay, clay and clay grade complexes will decrease with the increase of pH. The results were as follows: clay grade complex clay soil, and the maximum desorption amount of the three soils was reached at pH 5. The pH could affect the exchange of CD 2 and H by the hydrolysis of heavy metal Cd2. The adsorption surface type and surface charge of the soil and the CD partition coefficient in the desorption competition system have an effect on the adsorption of heavy metal cadmium ion.
【学位授予单位】：吉林农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53

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