Department of Civil and Environmental Engineering, University of South Carolina, Columbia, 300 Main Street, SC, 29208, USA.
Department of Environmental Engineering, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu, 41566, Republic of Korea; Department of Civil and Environmental Engineering, Korea Army Academy at Youngcheon, 495 Hogook-ro, Gokyungmeon, Youngcheon, Gyeongbuk, 38900, Republic of Korea.
Chemosphere. 2019 Sep;231:82-92. doi: 10.1016/j.chemosphere.2019.05.076. Epub 2019 May 17.
Graphene oxide (GO) and metal-organic framework (MOF) as adsorbents were applied to removal of Pb(II) with comprehensive characterizations and various experimental conditions. Various characterizations were conducted to clarify the physico-chemical properties of adsorbents. The analyses of adsorption experiments included (i) dosage amounts, (ii) isotherm and kinetic studies, and (iii) several factors related to water chemistry (i.e., solution pH, background ions, and humic acid). The maximum equilibrium adsorption capacity (q) for Pb(II) using the GO and MOF was 555 and 108 mg g, respectively, as determined in the optimum dosage experiments. Although the surface area of the MOF (629 m g) was much larger than that of the GO (19.8 m g), the adsorption capacity of the MOF was five times lower due to electrical repulsion. Thus, the MOF was utilized as the control group for comparison with the GO to evaluate the adsorption mechanisms in the experiments related to surface charge (i.e., under various pH and humic acid conditions). The adsorption isotherms and kinetics model determined using GO followed the Langmuir model (R > 0.99) and pseudo-second-order model (R > 0.99), respectively. Additionally, three adsorption-desorption cycles were conducted with the GO adsorbent to evaluate the maintenance of the removal ratio after regeneration and the equilibrium adsorption capacity was determined. Finally, the adsorption of other heavy metals (i.e., Cu(II), Cd(II), and Zn(II)), separately and in mixtures, was also evaluated to determine the selectivity of the adsorbents.
氧化石墨烯（GO）和金属有机骨架（MOF）作为吸附剂，通过全面的特性分析和各种实验条件，被应用于去除 Pb(II)。进行了各种特性分析以阐明吸附剂的物理化学性质。吸附实验的分析包括（i）剂量、（ii）吸附等温线和动力学研究，以及（iii）与水化学相关的几个因素（即溶液 pH 值、背景离子和腐殖酸）。在最佳剂量实验中，GO 和 MOF 对 Pb(II) 的最大平衡吸附容量（q）分别为 555 和 108mg/g。尽管 MOF 的表面积（629mg）远大于 GO（19.8mg），但由于电排斥，MOF 的吸附容量低了五倍。因此，MOF 被用作对照组，与 GO 进行比较，以评估与表面电荷相关的实验中的吸附机制（即在各种 pH 值和腐殖酸条件下）。GO 采用的吸附等温线和动力学模型分别遵循 Langmuir 模型（R>0.99）和准二级模型（R>0.99）。此外，使用 GO 吸附剂进行了三个吸附-解吸循环，以评估再生后去除率的保持情况，并确定平衡吸附容量。最后，还评估了其他重金属（即 Cu(II)、Cd(II)和 Zn(II)）的吸附，分别和混合吸附，以确定吸附剂的选择性。
