摘要
本研究合成了稳定分散的纳米银(AgNPs)颗粒,并采用批量试验法研究了水稻壳生物炭(BC)、多壁碳纳米管(CNTs)和石墨烯(GP)3种碳基材料对AgNPs的吸附特性以及环境因素(离子强度、离子种类和电解质pH)对AgNPs吸附的影响。结果表明:AgNPs在碳基材料上的吸附过程符合准二级动力学模型,吸附速率受内扩散和其他过程共同控制,并且在240min内均能达到吸附平衡;与Freundlich模型相比,Langmuir模型能够更好地拟合AgNPs在碳基材料上的等温吸附过程,并且AgNPs在BC、CNTs和GP上的吸附量依次增大,分别达到了69.15、87.78、121.21mg·g^(-1);在试验离子强度(20~100mmol·L^(-1))下,改变Na+强度对碳基材料吸附AgNPs的能力没有显著改变,但Ca2+强度的升高却抑制了GP对AgNPs的吸附,AgNPs在碳基材料上的吸附量随着电解质pH的升高而降低;BC通过络合作用、离子交换作用、沉淀作用和静电作用吸附AgNPs,CNTs和GP主要利用静电作用和范德华力固定溶液中的AgNPs。这些结果有助于了解AgNPs在碳基材料上的吸附行为,并可为更好地评价和管理AgNPs在环境中的风险提供依据。
In the present study,silver nanoparticles(Ag NPs)with good stability were synthesized,and we investigated their adsorption characteristics of biochar(BC),multi-walled carbon nanotubes(CNTs),and graphene(GP).The effects of environmental factors(ionic strength,ionic species,and solution pH)on the Ag NPs adsorption were also researched.The results showed that the pseudo-second order model better simulated the Ag NPs diffusion process.The Ag NPs adsorption rate was controlled by internal diffusion and other processes,and the adsorption equilibrium was reached within 240 min.The Langmuir model better reflected the isotherms of Ag NPs on carbon-based materials than the Freundlich model,and the Ag NPs adsorption capacities of BC,CNTs,and GP were 69.15,87.78 mg·g^-1,and 121.21 mg·g^-1,respectively.The Ag NPs adsorption amount was not affected significantly by the increasing strength of Na+,while increasing Ca^2+strength had a completely opposite result.The pH value of the electrolyte solution had a strong influence on Ag NPs adsorption.Acidic conditions promoted the adsorption of Ag NPs,and alkaline conditions obviously inhibited the process.BC adsorbed Ag NPs by complexation,ion exchange,precipitation,and electrostatic interaction,while CNTs and GP fixed the Ag NPs mainly through electrostatic interaction and Van der Waals forces.These results would be beneficial for an environmental risk assessment of Ag NPs.
作者
刘龙飞
刘艳丽
李成亮
李德云
曲兆鸣
LIU Long-fei;LIU Yan-li;LI Cheng-liang;LI De-yun;QU Zhao-ming(National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer,College of Resources and Environment,Shandong Agricultur.al University,Tai′an 271018,China)
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2018年第9期1986-1993,共8页
Journal of Agro-Environment Science
基金
国家自然科学基金项目(21377074)
关键词
碳基材料
纳米银颗粒
去除
吸附机理
carbon-based materials
silver nanoparticles
removal
sorption mechanisms
