New insights into the adsorption behavior and mechanism of alginic acid onto struvite crystals
New insights into the adsorption behavior and mechanism of alginic acid onto struvite crystals
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DOI：
10.1016/j.cej.2018.10.110
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发表时间：
2019-02
影响因子：
15.1
通讯作者：
Lin Wei;Tian-qiu Hong;Xiaoyang Li;Mingze Li;Qiang Zhang;Tianhu Chen
中科院分区：
文献类型：
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作者：
Lin Wei;Tian-qiu Hong;Xiaoyang Li;Mingze Li;Qiang Zhang;Tianhu Chen
鸟粪石结晶法是从富磷污泥中回收磷的最有前途的方法之一。然而，海藻酸，在富磷污泥中的胞外聚合物的替代品，对鸟粪石晶体的吸附已被证明显着抑制鸟粪石结晶。为全面了解海藻酸钠的抑制机理，研究了海藻酸钠在不同吸附时间、海藻酸浓度、pH值和离子强度下的吸附行为。随后，吸附等温线，动力学和热力学模型拟合吸附数据。有趣的是，通过X射线光电子能谱（XPS）和傅里叶变换红外光谱分析（FTIR），这是进一步解释了三层模型（TLM）的吸附机理进行了探讨。结果表明，鸟粪石晶体对水中有机物的吸附量在30 min内基本达到一个平台值。同时，吸附容量显着降低，随着pH值的增加，但略有增加，随着离子强度。吸附过程符合准二级动力学模型和Langmuir吸附等温线模型，颗粒内扩散是主要的限速步骤。此外，海藻酸与鸟粪石晶体之间的氢键和表面络合作用主导了吸附机理。此外，海藻酸通过两个外球表面络合物和一个内球表面络合物进行表面反应。研究结果有助于理解有机物对富磷污泥中鸟粪石结晶的抑制机理。
Struvite crystallization is one of the most promising routes for phosphorus recovery from phosphorus-rich sludge. However, the adsorption of alginic acid, a surrogate of extracellular polymeric substances in phosphorus-rich sludge, on struvite crystals has been proved to significantly inhibit struvite crystallization. To comprehensively understand the inhibitory mechanism, the adsorption behavior was evaluated at various adsorption time, the concentration of alginic acid, pH and ionic strength in the present study. Subsequently, adsorption equilibrium isotherm, kinetic and thermodynamics models were employed to fit the adsorption data. Interestingly, the adsorption mechanism was explored by X-ray photoelectron spectra (XPS) and Fourier transform infrared spectroscopy analysis (FTIR), which was further elucidated by triple-layer model (TLM). The results indicated that the adsorption capacity of struvite crystals almost reached a plateau value within the first 30 min. Meanwhile, the adsorption capacity was significantly reduced with increasing pH, but slightly increased with increasing ionic strength. Moreover, the adsorption process obeyed pseudo-second order kinetic model and Langmuir adsorption isotherm model, whereas intra-particle diffusion was a main rate-limited step. Furthermore, hydrogen bonding and surface complexation between alginic acid and struvite crystals dominated the adsorption mechanism. Additionally, alginic acid underwent surface reactions by virtue of two outer-sphere surface complexes and one inner-sphere surface complex. The findings presented herein will facilitate understanding of the inhibitory mechanism of organic matters on struvite crystallization from phosphorus-rich sludge.