Wang Siying, Wang Yili, Dong Shuoxun, Li Xiaolin, Liu Chenyang
College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing, 100083, China.
College of Environmental Science and Engineering, Beijing Key Lab for Source Control Technology of Water Pollution, Beijing Forestry University, Beijing, 100083, China.
Environ Res. 2023 Nov 1;236(Pt 1):116730. doi: 10.1016/j.envres.2023.116730. Epub 2023 Jul 25.
Phosphorus (P) removal from wastewater is critical for ecosystem operation and resource recovery. To facilitate the recycling of the used absorbents through balancing their adsorption and desorption performance on P, in this work, a novel porous magnetic La(OH)-loaded MAPTAC/chitosan (CTS)/polyethyleneimine (PEI) ternary composite hydrogel (p-MTCH-La(OH)) with enhanced bifunctional adsorption sites was synthesized by simultaneous dissolution of pre-embedded CaCO and CTS powder, followed by grafting PEI and loading La. Hierarchical porous channels promoted good dispersion of La(OH), bringing an excellent P adsorption capacity of 107.23 ± 4.96 mg P/g at neutral condition. PEI grafted with CTS increased the surface charge and enhanced the electrostatic attraction, which facilitated the desorption of P. The porous structure and abundant active sites also facilitated rapid adsorption with an adsorption rate constant of 0.1 g mg h. p-MTCH-La(OH) maintained effective P adsorption despite co-existence with competing substances and after 5 cycles. Further mechanistic analysis indicated that La-P inner sphere complexation and LaPO crystalline transformation were the main pathways for P removal. However, electrostatic interactions contributed 17.5%-46.7% of the adsorption amount during the first 30 min of rapid adsorption, enabling 92.8% of the adsorbed P at this stage to be desorbed by alkaline solution. Based on the variations of adsorption and desorption capacity with adsorption time, a rapid unsaturated adsorption of 1-2 h was proposed to facilitate the recycling of the adsorbent. This study proposed a method to promote P adsorption and desorption by enhancing bifunctional adsorption sites, and proved that p-MTCH-La(OH) is a promising phosphate adsorbent.
从废水中去除磷（P）对于生态系统运行和资源回收至关重要。为了通过平衡其对磷的吸附和解吸性能来促进用过的吸附剂的循环利用，在本工作中，通过同时溶解预先嵌入的碳酸钙和壳聚糖（CTS）粉末，接着接枝聚乙烯亚胺（PEI）并负载镧，合成了一种具有增强的双功能吸附位点的新型多孔磁性负载氢氧化镧的甲基丙烯酰氧乙基三甲基氯化铵/壳聚糖（CTS）/聚乙烯亚胺（PEI）三元复合水凝胶（p-MTCH-La(OH)）。分级多孔通道促进了氢氧化镧的良好分散，在中性条件下带来了107.23±4.96 mg P/g的优异磷吸附容量。与壳聚糖接枝的聚乙烯亚胺增加了表面电荷并增强了静电吸引力，这促进了磷的解吸。多孔结构和丰富的活性位点也促进了快速吸附，吸附速率常数为0.1 g mg h。尽管存在竞争物质且经过5次循环，p-MTCH-La(OH)仍保持有效的磷吸附。进一步的机理分析表明，镧-磷内球络合和磷酸镧结晶转变是磷去除的主要途径。然而，在快速吸附的前30分钟内，静电相互作用对吸附量的贡献为17.5%-46.7%，使得在此阶段吸附的磷中有92.8%能够被碱性溶液解吸。基于吸附和解吸容量随吸附时间的变化，提出了1-2小时的快速不饱和吸附以促进吸附剂的循环利用。本研究提出了一种通过增强双功能吸附位点来促进磷吸附和解吸的方法，并证明p-MTCH-La(OH)是一种有前途的磷酸盐吸附剂。
