氧化石墨烯(GO)在多平衡路线吸附(MER)过程中表现出显著的性能,其特征是通过基于单平衡路线吸附(SER)的原位还原过程进一步活化GO,产生新的吸附位点并实现吸附容量增加。然而,GO在横向尺寸和厚度上对MER吸附的影响尚不清楚。这里,GO片被超声处理不同的时间长度,研究了MER和SER在三个温度下的吸附去除典型的阳离子染料,吖啶橙(AO)。超声处理后,我们发现新鲜制备的GO在横向尺寸和厚度上大大减少。在大约30分钟内,GO的厚度从几个原子层到较少的原子层到单个原子层急剧减少,被完全剥离了;在那之后,单层横向尺寸减小占主导地位,直到它保持不变。表面功能位点,如羟基,实验中几乎没有变化。然而,GO主要还原MER中的C=O和C-O键,除了共轭碳主链(C-C)。所有温度的SER吸附动力学拟合了伪一阶和伪二阶模型,但室温更喜欢后者。整体吸附增强表现为超声处理时间,但SERGO的平衡容量通常随厚度增加而增加,随单层横向尺寸而减小,而MERGO则讨论了厚度。关于吸附机理,升高的温度促进了GO的剥离。因此,随着尺寸和温度的变化,SERGO的等温线行为从Freundlich模型变为Langmuir,而MERGO都是Freundlich。在313.15K下用60分钟的超声处理的GO从MER吸附获得了每克GO〜4.3gAO的记录容量。这项工作为使用GO作为吸附剂的MER吸附提供了基石。
Graphene oxide (GO) has shown remarkable performance in the multiple-equilibrium-route adsorption (MER) process, which is characterized by further activation of GO through an in-situ reduction process based on single-equilibrium-route adsorption (SER), generating new adsorption sites and achieving an adsorption capacity increase. However, the effect of GO on MER adsorption in lateral size and thickness is still unclear. Here, GO sheets were sonicated for different lengths of time, and the adsorption of MER and SER was investigated at three temperatures to remove the typical cationic dye, acridine orange (AO). After sonication, we found that freshly prepared GO was greatly reduced in lateral size and thickness. In about 30 min, the thickness of GO decreased dramatically from several atomic layers to fewer atomic layers to a single atomic layer, which was completely stripped off; after that, the monolayer lateral size reduction dominated until it remained constant. Surface functional sites, such as hydroxyl groups, showed little change in the experiments. However, GO mainly reduces the C=O and C-O bonds in MER, except for the conjugated carbon backbone (C-C). The SER adsorption kinetics of all temperatures fitted the pseudo-first-order and pseudo-second-order models, yet room temperature preferred the latter. An overall adsorption enhancement appeared as sonication time, but the equilibrium capacity of SER GO generally increased with thickness and decreased with the single-layer lateral size, while MER GO conversed concerning the thickness. The escalated temperature facilitated the exfoliation of GO regarding the adsorption mechanism. Thus, the isotherm behaviors of the SER GO changed from the Freundlich model to Langmuir as size and temperature changed, while the MER GO were all of the Freundlich. A record capacity of ~4.3 g of AO per gram of GO was obtained from the MER adsorption with a sixty-minute ultrasonicated GO at 313.15 K. This work promises a cornerstone for MER adsorption with GO as an adsorbent.