Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi, 832003, China.
Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi, 832003, China; International Joint Research Center for Green Energy Chemical Engineering, East China University of Science and Technology, Shanghai, 200237, China.
Environ Res. 2021 Oct;201:111489. doi: 10.1016/j.envres.2021.111489. Epub 2021 Jun 22.
Herein, we report a novel renewable pH-responsive starch-based flocculant (CIAT-ST) via etherifying 2-chloro-4,6-isopropylamino-[1,3,5]-triazine (CIAT) onto the starch backbones for decontamination and reuse of highly saline effluents. The obtained CIAT-ST shows a unique pH-sensibility and reversibility in response to a subtle pH change due to a pH-controllable surface charge density of polymer chains. The level of residual CIAT-ST in the solution can be facilely monitored by using UV-vis detection. The dye flocculation performance of CIAT-ST was evaluated by using a batch experiment. The results exhibited that the dye removal was highly dependent on the solution pH (optimal pH was 2), the flocculation equilibrium can be achieved within 5 min, and the maximum flocculation capacity of CIAT-ST for K-2BP and KN-B5 were calculated to be 2452.6 ± 23.9 and 792.7 ± 14.1 mg/g, respectively. The multiple flocculation mechanisms, including charge neutralization, bridging and charge patching, may participate in the flocculation process. Adjustment in pH-mediated hydrophilicity-hydrophobicity switch of flocculant facilitates readily recovery and then sequentially reused three times while retaining satisfying flocculation efficiency. A significant contribution was also confirmed that the highly saline effluents after flocculation and sedimentation were reused in three successive dyeing processes without sacrificing fabric quality (ΔE* < 1) due to relatively low polymer residuals, and the efficiency of salt reuse for consecutive regeneration processes could be achieved above 85%. The present work could provide alternative thoughts for the reutilization of spent flocculant and clarified saline wastewater, which is also an efficient and sustainable strategy for textile wastewater management.
在此，我们通过将 2-氯-4,6-异丙氨基-[1,3,5]-三嗪（CIAT）醚化到淀粉骨架上来报告一种新型可再生 pH 响应淀粉基絮凝剂（CIAT-ST），用于处理高盐废水并进行再利用。所得到的 CIAT-ST 由于聚合物链的表面电荷密度可控，因此在 pH 发生细微变化时表现出独特的 pH 敏感性和可逆性。可以通过使用紫外可见检测法轻松监测溶液中残留的 CIAT-ST 水平。通过使用分批实验评估了 CIAT-ST 的染料絮凝性能。结果表明，染料去除高度依赖于溶液 pH（最佳 pH 为 2），在 5 分钟内可以达到絮凝平衡，CIAT-ST 对 K-2BP 和 KN-B5 的最大絮凝容量分别计算为 2452.6±23.9 和 792.7±14.1mg/g。多种絮凝机制，包括电荷中和、桥联和电荷修补，可能参与了絮凝过程。通过调节 pH 介导的亲水性-疏水性转换，絮凝剂易于回收，然后可重复使用三次，同时保持令人满意的絮凝效率。还证实了一个重要贡献，即经过絮凝和沉淀后的高盐废水可以在三个连续的染色过程中重复使用，而不会因聚合物残留量相对较低而牺牲织物质量（ΔE*<1），并且连续再生过程中的盐再利用率可以达到 85%以上。本工作为处理后的絮凝剂和澄清的含盐废水的再利用提供了替代思路，也为纺织废水管理提供了一种高效且可持续的策略。
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