State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
Chemosphere. 2021 Aug;277:130268. doi: 10.1016/j.chemosphere.2021.130268. Epub 2021 Mar 15.
The effective removal of humic acid (HA) by coagulation has been extensively investigated for water treatments. However, the limitations of pH variation and excessive residual aluminum issues were still factors needed to be considered. In this study, to investigate the coagulation mechanism for removing HA by Al and optimize Al operation for removing HA, Al and preformed Al aggregates (Alagg) were applied to remove HA at different pH conditions. The results showed that preformed Alagg exhibited superior HA removal performance than Al due to its wide pH range and low residual Al level. During coagulation, Al and Alagg interacted with HA in their original status, but the DSlope difference implied that the complexation capacity between HA and Alagg was stronger than Al. The new peaks of HPSEC representing larger molecular weight substances were formed under acidic and neutral conditions, which indicated that HA firstly aggregated into larger complexed molecules by interacting with Al or its hydrolysates and was subsequently removed by forming large flocs which was completely different from Alagg situation. Therefore, the different coagulation mechanisms played the roles in HA removal for Al and Alagg which were studied in this paper. It was believed that the complexation and charge neutralization effects dominated coagulation process for Al while sweep flocculation and adsorption coagulation were main driving force for Alagg in HA removing. This work provides significant understanding of HA removal by Al and Alagg coagulation, which can help to design and optimize the high efficiency coagulant based on Al polycations.
混凝法有效去除腐殖酸（HA）已被广泛研究用于水处理。然而，pH 值变化和过量残余铝的限制仍然是需要考虑的因素。在本研究中，为了研究 Al 去除 HA 的混凝机理并优化 Al 的操作以去除 HA，分别采用 Al 和预形成的 Al 聚集体（Alagg）在不同 pH 条件下去除 HA。结果表明，由于较宽的 pH 范围和较低的残余铝水平，预形成的 Alagg 比 Al 具有更优的 HA 去除性能。在混凝过程中，Al 和 Alagg 以其原始状态与 HA 相互作用，但 DSlope 的差异表明，HA 与 Alagg 之间的络合能力强于 Al。在酸性和中性条件下形成了新的代表更大分子量物质的 HPSEC 峰，这表明 HA 首先通过与 Al 或其水解产物相互作用聚集形成较大的络合分子，然后通过形成大絮体被去除，这与 Alagg 的情况完全不同。因此，在本文研究中，Al 和 Alagg 对 HA 的去除机制不同。认为 Al 混凝过程主要以络合和电荷中和效应为主，而 Alagg 去除 HA 的主要驱动力是扫流絮凝和吸附混凝。这项工作为 Al 和 Alagg 混凝去除 HA 提供了深入的了解，有助于设计和优化基于 Al 多阳离子的高效混凝剂。
