Liu Gongyan, Yu Ruiquan, Lan Tianxiang, Liu Zheng, Zhang Peng, Liang Ruifeng
National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University Chengdu 610065 China.
The Key Laboratory of Leather Chemistry and Engineering of Ministry of Education, Sichuan University Chengdu 610065 China.
RSC Adv. 2019 Aug 29;9(46):27060-27068. doi: 10.1039/c9ra05664e. eCollection 2019 Aug 23.
The pollution caused by tannery wastewater containing high concentrations of trivalent chromium ions [Cr(iii)] and organic dyes has severely restricted the sustainable development of the leather industry. To address this problem, a three-dimensional (3D) porous graphene-based hydrogel with good mechanical strength and large surface area was fabricated by self-assembly of graphene oxide (GO) sheets reduced and modified by gallic acid (GA) through π-π interactions. As an adsorbent, this GA-functionalized graphene hydrogel (GA-GH) can effectively capture Cr(iii) by coordination complexation between Cr(iii) and deprotonated carboxylic groups of GA at pH ∼ 4.0. Moreover, GA-GH could be easily regenerated by desorption of adsorbed Cr(iii) at pH 2.0 and maintained its high adsorption capacity after multiple adsorption-desorption cycles, which was also helpful for reusing desorbed Cr(iii) as tanning agent. In addition, compared with a graphene hydrogel (GH) without modification by GA, adsorption capacity of GA-GH for organic dye was significantly improved due to the enhanced π-π interactions between the GA-GH and aromatic dyes.
含有高浓度三价铬离子[Cr(iii)]和有机染料的制革废水所造成的污染，严重制约了皮革行业的可持续发展。为了解决这一问题，通过没食子酸(GA)还原和改性的氧化石墨烯(GO)片材通过π-π相互作用自组装，制备了一种具有良好机械强度和大表面积的三维(3D)多孔石墨烯基水凝胶。作为一种吸附剂，这种GA功能化石墨烯水凝胶(GA-GH)在pH值约为4.0时，通过Cr(iii)与GA去质子化羧基之间的配位络合作用，能有效捕获Cr(iii)。此外，GA-GH在pH值为2.0时，通过吸附的Cr(iii)解吸可轻松再生，并且在多次吸附-解吸循环后仍保持其高吸附容量，这也有助于将解吸的Cr(iii)作为鞣剂再利用。此外，与未经GA改性的石墨烯水凝胶(GH)相比，GA-GH与芳香族染料之间增强的π-π相互作用显著提高了其对有机染料的吸附能力。
