In this study, a pH-sensitive nanocomposite hydrogel based on poly(vinyl alcohol) (PVA)/graphene oxide (GO) was prepared and used as a potential adsorbent for the removal of crystal violet (CV) and methylene blue (MB) from aqueous solutions. The prepared nanocomposite hydrogels were fully characterized and their swelling capacity and gel content were investigated by changing the GO and acrylic acid (AA) content. Adsorption experiments were carried out as a function of contact time, concentration, temperature, pH and dosage. The adsorption process was favored at higher pHs, followed pseudo second-order kinetics while the adsorption equilibrium data well fitted to the Langmuir isotherm model with the maximum capacity of 173.2 and 169.6 mg g⁻¹ for MB and CV, respectively. A thermodynamic study showed the spontaneity nature of the adsorption process for MB and CV. The removal percentage of MB dye increased with increase of temperature from 25 to 55 °C while the adsorption of CV dye showed the opposite trend. This different trend can be attributed to the differences in the pattern of adsorption.

Graphic Abstract

中文翻译：

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基于聚乙烯醇大分子单体和氧化石墨烯的pH敏感纳米复合水凝胶用于去除水溶液中的阳离子染料

在这项研究中，制备了一种基于聚乙烯醇（PVA）/氧化石墨烯（GO）的pH敏感纳米复合水凝胶，并将其用作潜在的吸附剂，用于从中去除结晶紫（CV）和亚甲基蓝（MB）水溶液。充分表征了所制备的纳米复合水凝胶，并通过改变GO和丙烯酸（AA）的含量研究了它们的溶胀能力和凝胶含量。根据接触时间，浓度，温度，pH和剂量进行吸附实验。较高的pH值有利于吸附过程，遵循伪二级动力学，而吸附平衡数据完全符合Langmuir等温模型，最大容量为173.2和169.6 mg g ^-1分别用于MB和CV。热力学研究显示了MB和CV吸附过程的自发性。随着温度从25升高到55°C，MB染料的去除率增加，而CV染料的吸附却呈现相反的趋势。这种不同的趋势可以归因于吸附方式的差异。

图形摘要