摘要
研究了锰氧化物石英砂(MOCS)吸附剂对Cu2 + 和Pb2 + 的吸附行为,考察了吸附剂用量、平衡时间、温度、盐浓度、溶液的pH值等因素对MOCS吸附的影响.结果表明,MOCS对Cu2 + 和Pb2 + 的吸附在3h基本达到吸附平衡,吸附量随着溶液的pH值增大、温度的升高以及盐浓度的降低而增加,在单一体系以及混合体系中对Cu2 + 和Pb2 + 的吸附均符合Langmiur吸附等温式,温度从15℃升高到45℃,Cu2 + 和Pb2 + 的饱和吸附容量(qm)分别从13 4μmol·g- 1 和15 5 μmol·g- 1 升高到16 4μmol·g- 1 和18 1μmol·g- 1 .Cu2 + 和Pb2 + 吸附反应的ΔGo 均为负值,焓变ΔHo 为正值,说明该吸附过程是自发的吸热反应.利用准一级动力学方程、准二级动力学方程以及粒子扩散方程的数学模型检验了吸附过程的动力学性质,表明MOCS对Cu2 + 和Pb2 + 的吸附过程符合准二级反应动力学模型.计算了不同温度下3个动力学方程的吸附速率常数K值.根据准二级反应的吸附速率常数K值,求得MOCS对Cu2 + 和Pb2 + 的吸附活化能(Ea)分别为92 3kJ·mol- 1 和119kJ·mol- 1 .在混合体系中,共存离子的存在影响金属离子的吸附效率;Cu2 + 存在时,Pb2 + 的饱和吸附量下降了2 4 4% ,而Pb2 + 存在时,Cu2 + 的饱和吸附量下降了93 8% .MOCS对Cu2 + 和Pb2 + 的吸附强弱?
The removal of copper and lead cations from aqueous systems by manganese-oxide-coated-sand (MOCS) was studied in single (non-competitive) and binary (competitive) component sorption systems. The adsorption of the investigated heavy metal ions by MOCS strongly depended on pH, contact time, salt concentration and initial concentration of the heavy metal ions. The experimental results showed that the equilibrium time of adsorbing copper and lead cations were 3?h. The adsorption data on MOCS were followed by both Freundlich and Langmuir models. The data were fitted better by the Langmuir isotherm compared Freundlich model in both the single- and binary-component systems. The maximum adsorption capacity of copper and lead cations per gram MOCS in single component sorption systems calculated from Langmiur isotherm were from 13.4?μmol and 15.5?μmol to 16.4?μmol and 18.1?μmol for the temperature range of 15℃～45℃, respectively. From the results of the thermodynamic analysis, standard free energy ΔGo, standard enthalpy ΔHo, and standard entropy ΔSo in the adsorption process were calculated. The values showed the adsorptions of copper and lead cations by MOCS were a spontaneous and endothermic process. The pseudo-first-order kinetic model, pseudo-second-order kinetic model and intraparticle diffusion model were used to describe the kinetics data, and the rate constants of adsorption for all these kinetic models were calculated. The dynamic data fitted the pseudo-second-order kinetic model well. The dynamic parameter and the standard activation energy (E_a) were also calculated. The values of activation energy (E_a) were 92.3?kJ·mol -1 and 119?kJ·mol -1 for the adsorption of copper and lead cations onto MOCS, respectively. Experiments of the competitive adsorption illustrated that the removal of metal ions decreased when other metal ions were added. This competitive adsorption showed that the maximum adsorption efficiency of lead cation was reduced 24.4% in the presence of 1.26?mmol·L -1 copper cation, whe
出处
《环境科学学报》
CAS
CSCD
北大核心
2005年第6期779-784,共6页
Acta Scientiae Circumstantiae
基金
南省科技攻关资助项目 (No .0 42 42 90 65 )
河南省教育厅科技攻关资助项目 (No .2 0 0 5 10 45 90 16)~~
关键词
MOCS
铜离子
铅离子
吸附
manganese-oxide-coated-sand(MOCS)
copper cation
lead cation
adsorption
