Department of Civil and Environmental Engineering, National University of Singapore, Kent Ridge Crescent, Singapore, 119260, Singapore.
Department of Civil and Environmental Engineering, National University of Singapore, Kent Ridge Crescent, Singapore, 119260, Singapore; NUS Environmental Research Institute, National University of Singapore, 5A Engineering Drive 1, #02-01, Singapore, 117411, Singapore.
Chemosphere. 2022 Nov;306:135468. doi: 10.1016/j.chemosphere.2022.135468. Epub 2022 Jun 24.
Presence of excessive phosphorus in surface waters is the main cause for eutrophication. In this study, a lanthanum/chitosan (La/CS) bead was prepared so as to provide a cost-effective solution to the problem. The optimization of bead for the treatment was conducted, leading to the optimal condition: 30 wt% La/CS bead at a dosage of 30 g L (wet weight). A higher phosphate removal around 90% was obtained in pH 4.0-10.0. Most of uptake occurred in the first 2 h and the equilibrium was reached in about 6 h. Coexisting ions of Cl, [Formula: see text] , [Formula: see text] , and [Formula: see text] had negligible effects on the treatment, while the presence of F reduced the uptake by 10.39%. The maximum adsorption capacity of 261.1 mg-PO·g (dried weight) at pH 5.0 was achieved, which is much better than many reported La-based adsorbents. The adsorbed phosphate can be effectively recovered with an alkaline solution. A multi-cycle regeneration-reuse study illustrated that the treated water still met the phosphorus discharge standard. The characterization results demonstrated the disappearance of La(OH) and La(CO) on the bead and the formation of NH … P and La-P groups after the adsorption, indicating the significant roles of ion exchange and electrostatic attraction on the uptake. The excellent performance found in this study clearly indicates that the optimized La/CS bead is promising in the treatment of phosphate and perhaps its recovery for industrial use.
水体中过量的磷是富营养化的主要原因。在本研究中，制备了镧/壳聚糖（La/CS）珠，以提供一种经济有效的解决方案。对珠进行了处理优化，得到了最佳条件：30wt%La/CS 珠，用量为 30g·L（湿重）。在 pH 值为 4.0-10.0 时，磷酸盐的去除率高达 90%左右。大部分吸附发生在最初的 2 小时内，约 6 小时达到平衡。共存的 Cl、[Formula: see text]、[Formula: see text]和[Formula: see text]离子对处理几乎没有影响，而 F 的存在使吸附减少了 10.39%。在 pH 值为 5.0 时，达到了 261.1mg-PO·g（干重）的最大吸附容量，明显优于许多已报道的基于镧的吸附剂。吸附的磷酸盐可以用碱性溶液有效地回收。多周期再生-重复使用研究表明，处理后的水仍符合磷排放标准。表征结果表明，吸附后珠上的 La(OH)和 La(CO)消失，形成了 NH…P 和 La-P 基团，这表明离子交换和静电吸引在吸附过程中起着重要作用。本研究中发现的优异性能清楚地表明，优化后的 La/CS 珠在处理磷酸盐方面具有很大的应用前景，并且可能将其回收用于工业用途。
