研究报告
王竞峰,王欣,成家杨,张波.3种海洋硅藻藻粉吸附水中镉离子特性研究[J].环境科学学报,2017,37(12):4549-4561
3种海洋硅藻藻粉吸附水中镉离子特性研究
- Properties of cadmium ion adsorption from water by three kinds of dry marine diatom biomass
- 基金项目：海洋公益性行业科研专项（No.201305022）；广东省自然科学基金博士启动项目（No.2014A030310326）
- 作者
- 单位
- 王竞峰
- 北京大学环境与能源学院, 深圳 518055
- 王欣
- 北京大学环境与能源学院, 深圳 518055
- 成家杨
- 北京大学环境与能源学院, 深圳 518055
- 张波
- 中国石化集团国际石油工程有限公司, 北京 100020
- 摘要：利用3种海洋硅藻（角毛藻、菱形藻、海链藻）干粉对水中重金属镉离子进行吸附.实验结果表明，3种海洋硅藻对Cd2+的吸附容量在一定范围内均与吸附时间、Cd2+初始浓度和温度3个变量分别呈正相关关系.3种硅藻干粉对Cd2+的吸附均很好地符合Pseudo二级动力学模型；吸附等温数据均更符合Langmuir等温吸附；在不考虑温度对吸附焓和吸附熵影响的前提下，计算得到的3种海洋硅藻的ΔG值均小于0.以上结果表明，3种海洋硅藻对Cd2+的吸附过程是一个自发进行、有化学吸附参与的以单分子层吸附为主的吸附过程.角毛藻、菱形藻和海链藻最大实验吸附容量分别为275.25、303.75和224.36 mg·g-1，大大高于已报道各类生物吸附剂.以吸附容量最大的菱形藻干粉为吸附剂，考察实际水体中可能存在物质对其吸附性能的影响.结果表明，菱形藻对Cd2+的吸附容量随着溶液中盐（NaCl、Ca（NO3）2、Mg（NO3）2）浓度和浊度的增加而下降，而随着腐植酸浓度的增加不断升高.最后，利用HCl对吸附Cd2+后的菱形藻进行解吸附再生实验，结果表明HCl可有效解吸菱形藻上的Cd2+，实现Cd2+的脱附回收.
- Abstract：Three kinds of dry marine diatom biomass (Chaetoceros, Nitzschia, Thalassiosira) were used to adsorb Cd2+ from water in this study. Results suggest that the adsorption capacity of each diatom biomass was positively related to the adsorption time, initial concentration of Cd2+ and temperature. The adsorption process of Cd2+ on each diatom biomass was well fitted by the pseudo-second-order model. The Cd2+ adsorption on each diatom biomass could be better described by the Langmuir isotherm model than Freundlich model. It is assumed that the adsorption enthalpy and adsorption entropy are independent of temperature, the adsorption free energy (ΔG) of Cd2+ adsorption by each diatom biomass was calculated to be negative. It can be inferred from these results that the adsorption of Cd2+ on these three diatom biomass was a spontaneous, endothermic and monolayer adsorption process with involvement of chemical adsorption. The maximum adsorption capacities of Cd by Chaetoceros, Nitzschia, Thalassiosira in this study were 275.25, 303.75 and 224.36 mg·g-1, respectively, which were significantly higher than that of bio-adsorbents reported. Effects of possible substances in real wastewater on Cd2+ adsorption capacity of Nitzschia which possessed the greatest adsorption performance among three diatom species were further investigated. Results suggest that the Cd2+ adsorption capacity of Nitzschia decreased with salt (NaCl, Ca(NO3)2, Mg(NO3)2) concentration and turbidity, but increased with humic acid concentration. Finally, Cd2+ desorbed from Nitzschia in HCl solution. And results show that HCl can effectively remove Cd2+ from diatom and make Cd2+ recoverable.
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