In the present study, the used graphene nanoplatelets (GNPs) are of high structural quality offering the opportunity to modify the adsorbent/adsorbate interactions. Their chemical modification by simple acid oxidation leads to their facile dispersion in water. Morphological, structural, and chemical properties of the functionalized GNPs are deeply investigated by a set of complementary characterization techniques. The parametric investigation including effects of initial concentration, contact time, solution pH, and temperature of methylene blue (MB) adsorption allows to identify those being relevant for MB removal enhancement. MB adsorption is found to increase with contact time, solution temperature, and acidic pH. The nature of the MB-GNP interactions and the possible adsorption mechanisms, relatively little understood, are here particularly studied. MB-GNP adsorption is shown to follow a Langmuir isotherm and a pseudo-first-order kinetic model. The adsorption capacity of MB on the chemically modified GNPs (q_m = 225 mg/g) with respect to the external surface is relatively high compared to other carbon nanomaterials. Such adsorbent certainly merits further consideration for removal of other dyes and heavy metals from wastewaters.

Graphical abstract

在本研究中，所使用的石墨烯纳米片（GNP）具有较高的结构质量，为修饰吸附剂/被吸附物的相互作用提供了机会。它们通过简单的酸氧化进行化学修饰，使其易于在水中分散。通过一系列互补的表征技术，对功能化GNP的形态，结构和化学性质进行了深入研究。参数研究包括初始浓度，接触时间，溶液pH值和亚甲基蓝（MB）吸附温度的影响，从而可以确定与MB去除增强有关的那些参数。发现MB吸附随着接触时间，溶液温度和酸性pH值的增加而增加。MB-GNP相互作用的性质和可能的吸附机理，对此了解甚少，在这里进行了专门研究。MB-GNP吸附遵循Langmuir等温线和拟一级动力学模型。MB在化学修饰的GNP上的吸附能力（ 与其他碳纳米材料相比，相对于外表面的q _m = 225 mg / g）相对较高。这种吸附剂无疑值得进一步考虑从废水中去除其他染料和重金属。

图形概要