Rajput Shalini, Pittman Charles U, Mohan Dinesh
School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
Department of Chemistry, Mississippi State University, Mississippi State, MS 39762, USA.
J Colloid Interface Sci. 2016 Apr 15;468:334-346. doi: 10.1016/j.jcis.2015.12.008. Epub 2015 Dec 14.
Magnetic magnetite (Fe3O4) nanoparticles synthesized by chemical co-precipitation were characterized using XRD, TEM, SEM-EDX, FT-IR, ED-XRF, PPMS, point of zero charge (pHpzc) and surface area measurements. As-prepared Fe3O4 nanoparticles were successful for aqueous Cr(6+) and Pb(2+) removal. Batch adsorption experiments systematically investigated the influence of pH, temperature, contact time and adsorbate/adsorbent concentration on Cr(6+) and Pb(2+) adsorption. Maximum Cr(6+) and Pb(2+) removal occurred at pH 2.0 and 5.0, respectively. Sorption data fit pseudo-second order kinetics, indicating a chemical adsorption. The Freundlich, Langmuir, Redlich-Peterson, Toth, Radke and Sips adsorption isotherm models were applied to describe equilibrium data. The Sips and Langmuir models best described Cr(6+) and Pb(2+) adsorption on magnetite nanoparticles, respectively. The maximum Langmuir adsorption capacities were 34.87 (Cr(6+)) and 53.11 (Pb(2+))mg/g at 45°C, respectively. Fe3O4 nanoparticles are promising potential adsorbents and exhibited remarkable reusability for metal ions removal in water and wastewater treatment.
采用化学共沉淀法合成的磁性磁铁矿（Fe3O4）纳米颗粒，通过X射线衍射（XRD）、透射电子显微镜（TEM）、扫描电子显微镜-能谱仪（SEM-EDX）、傅里叶变换红外光谱（FT-IR）、能量色散X射线荧光光谱（ED-XRF）、物理性能测量系统（PPMS）、零电荷点（pHpzc）和比表面积测量等手段进行了表征。制备的Fe3O4纳米颗粒成功用于去除水溶液中的Cr(6+)和Pb(2+)。分批吸附实验系统研究了pH值、温度、接触时间以及吸附质/吸附剂浓度对Cr(6+)和Pb(2+)吸附的影响。Cr(6+)和Pb(2+)的最大去除率分别出现在pH值为2.0和5.0时。吸附数据符合准二级动力学，表明是化学吸附。应用Freundlich、Langmuir、Redlich-Peterson、Toth、Radke和Sips吸附等温线模型来描述平衡数据。Sips模型和Langmuir模型分别最能描述Cr(6+)和Pb(2+)在磁铁矿纳米颗粒上的吸附情况。在45°C时，Langmuir最大吸附容量分别为34.87（Cr(6+)）和53.11（Pb(2+)）mg/g。Fe3O4纳米颗粒是很有前景的潜在吸附剂，在水和废水处理中对金属离子的去除表现出显著的可重复使用性。
