Zhao Lianqin, Yang Sheng-Tao, Feng Shicheng, Ma Qiang, Peng Xiaoling, Wu Deyi
School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800 Dongchuan Road, Shanghai 200240, China.
College of Chemistry and Environment Protection Engineering, Southwest University for Nationalities, Chengdu 610041, China.
Int J Environ Res Public Health. 2017 Oct 26;14(11):1301. doi: 10.3390/ijerph14111301.
Spongy graphene is a newly developed adsorbent of high performance for water treatment. Proper functionalization is an efficient approach to improve the adsorption capacity of graphene adsorbents. In this study, we prepared graphene oxide (GO), functionalized it with carboxyl groups to produce carboxylated GO (GO-COOH) dispersion, and lyophilized the GO-COOH dispersion to obtain the GO-COOH sponge. The adsorption isotherm, kinetics, thermodynamics, influencing factors, and regeneration of the adsorption of dye methylene blue (MB) on GO-COOH sponge were evaluated in batch experiments. The adsorption capacity of GO-COOH sponge was measured as 780 mg/g, which was nearly twice that of GO sponge (446 mg/g). The adsorption isotherm could be well described by the Freundlich model with a of 508 (L/mg). The adsorption kinetic was nicely fitted by pseudo-first-order model with a ₁ of 0.00157·min. In thermodynamics analysis, the negative Δ indicated the spontaneous nature of adsorption on GO-COOH sponge. The adsorption process was endothermic and was driven by the increase of entropy. Higher pH benefited the removal of MB by GO-COOH sponge and the ionic strength had no meaningful effect. The regeneration was poor due to the strong electrostatic interaction between MB and the GO-COOH sponge. The results collectively suggested that carboxylation increased the adsorption performance of GO sponge.
海绵状石墨烯是一种新开发的用于水处理的高性能吸附剂。适当的功能化是提高石墨烯吸附剂吸附能力的有效方法。在本研究中，我们制备了氧化石墨烯（GO），用羧基对其进行功能化以制备羧基化氧化石墨烯（GO-COOH）分散液，并将GO-COOH分散液冻干以获得GO-COOH海绵。通过批量实验评估了GO-COOH海绵对染料亚甲基蓝（MB）吸附的等温线、动力学、热力学、影响因素和再生情况。测得GO-COOH海绵的吸附容量为780 mg/g，几乎是GO海绵（446 mg/g）的两倍。吸附等温线可以用Freundlich模型很好地描述，其中 为508（L/mg）。吸附动力学用伪一级模型拟合良好， ₁为0.00157·min。在热力学分析中，负的Δ表明在GO-COOH海绵上吸附的自发性。吸附过程是吸热的，由熵的增加驱动。较高的pH值有利于GO-COOH海绵去除MB，而离子强度没有显著影响。由于MB与GO-COOH海绵之间的强静电相互作用，再生效果较差。这些结果共同表明羧基化提高了GO海绵的吸附性能。
