Kinetic and Mechanistic Evaluation of Inorganic Arsenic Species Adsorption onto Humic Acid Grafted Magnetite Nanoparticles
Kinetic and Mechanistic Evaluation of Inorganic Arsenic Species Adsorption onto Humic Acid Grafted Magnetite Nanoparticles
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DOI：
10.1021/acs.jpcc.7b12438
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发表时间：
2018-06-28
影响因子：
3.7
通讯作者：
O'Shea, Kevin E.
中科院分区：
文献类型：
--
作者：
Rashid, Mamun;Sterbinsky, George E.;O'Shea, Kevin E.
合成、表征和研究了腐植酸包裹的磁性氧化铁纳米颗粒(HA-MNPs)对水介质中有毒无机砷的去除。As(III)和As(V)的吸附遵循准二级动力学，并用Freundlich吸附等温式对实验数据进行了精确的拟合。应用Weber和Morris的颗粒内扩散模型对观察到的动力学数据进行分析表明，吸附分三个不同的阶段进行，即快、中、慢步骤。我们认为，初始阶段是由表面缔合控制的，随后是砷在HA基质中的颗粒内扩散，最后是砷物种与HA官能团之间的化学反应或结合。HA-MNP纳米吸附剂吸附水介质中95%的无机砷，吸附容量为12.2-12.6 mg/g，在各种条件下都有效。砷吸附后纳米颗粒的表征表明，As(III)通过提议的酯型键与HA的羧酸基结合，而HA中的亲核官能团与As(V)中的亲电砷原子之间可以发生亲电反应。结果表明，HA-MNPs具有很强的稳定性，有望有效修复As(III)和As(V)。
Humic acid coated magnetic iron oxide nanoparticles (HA-MNPs) were synthesized, characterized, and studied for the removal of toxic inorganic arsenic species from aqueous media. The adsorption of As(III) and As(V) followed pseudo second-order kinetics, and the observed data were accurately modeled employing the Freundlich adsorption isotherm. Application of the Weber and Morris intraparticle diffusion model to the observed kinetic data suggests that the adsorption occurs in three distinct stages, fast, intermediate, and slow steps. We propose the initial stage is governed by surface association, followed by intraparticle diffusion of arsenic through the HA matrix and, finally, chemical reaction or bonding between the arsenic species and HA functionality. The HA-MNP nanoadsorbent absorbs >95% of the inorganic arsenic species with an absorption capacity of 12.2-12.6 mg/g from aqueous media and is effective under a variety of conditions. Post arsenic adsorption characterization of the nanoparticles suggests that As(III) binds with the carboxylate group of HA through a proposed ester type linkage, while electrophilic reactions can occur between the nucleophilic functional groups present in HA and the electrophilic arsenic atom in As(V). The results obtained demonstrated that HA-MNPs are robust and have promise for effective As(III) and As(V) remediation.