Chen Changtao, Zhang Tao, Lv Li, Chen Yanxiao, Tang Wenxiang, Tang Shengwei
Sichuan Base of International Science and Technology Cooperation for Green Chemical Industry, School of Chemical Engineering, Sichuan University, Chengdu, 610065, China.
J Environ Manage. 2023 Apr 1;331:117291. doi: 10.1016/j.jenvman.2023.117291. Epub 2023 Jan 17.
The huge output of sewage sludge has caused a remarkable environmental burden. Sludge dewatering is considered as an important way to reduce the sludge volume. Five imidazole-based ionic liquids were used to improve the dewaterability of sewage sludge. 1-ethyl-3-methylimidazolium dihydrogen phosphate ([Emim][HPO]) was screened out as a potential conditioner of sludge due to its excellent dewatering performance and reusability. The solid content of sludge filter cake after treatment with [Emim][HPO] was about 10% higher than that of sludge treated by cationic polyacrylamides (CPAM). The intensification mechanism of ionic liquids to the improvement of sludge dewatering performance was studied. The presence of acidic ionic liquids [Emim][HPO] resulted the increase of zeta potential from -14.57 ± 0.81 mV to -5.60 ± 0.30 mV and led to the protonation of biopolymers. Acidic ionic liquids [Emim][HPO] inactivated the microorganism and led to a porous and unconsolidated structure of the solid sludge particles. All these effects were conducive to destroy the microstructure of sludge and release water. However, [Emim]Cl, [Bmim][OTf] and [Hmim][OTf] showed little effect on the protonation of ionizable functional groups at near-neutral environment. The dissolution of biopolymer decreased the zeta potential and strengthened the electrostatic repulsion. So, they showed weaker intensification effects than CPAM.
大量的污水污泥产出造成了显著的环境负担。污泥脱水被认为是减少污泥体积的重要途径。使用了五种咪唑基离子液体来提高污水污泥的脱水性能。1-乙基-3-甲基咪唑磷酸二氢盐（[Emim][HPO]）因其出色的脱水性能和可重复使用性而被筛选为潜在的污泥调理剂。用[Emim][HPO]处理后的污泥滤饼固体含量比用阳离子聚丙烯酰胺（CPAM）处理的污泥高约10%。研究了离子液体对改善污泥脱水性能的强化机制。酸性离子液体[Emim][HPO]的存在使ζ电位从-14.57±0.81 mV增加到-5.60±0.30 mV，并导致生物聚合物质子化。酸性离子液体[Emim][HPO]使微生物失活，并导致固体污泥颗粒形成多孔且疏松的结构。所有这些作用都有利于破坏污泥的微观结构并释放水分。然而，[Emim]Cl、[Bmim][OTf]和[Hmim][OTf]在近中性环境下对可电离官能团的质子化作用很小。生物聚合物的溶解降低了ζ电位并增强了静电排斥力。因此，它们的强化效果比CPAM弱。
