与水铁矿共沉淀的腐殖酸的粒径，电荷和胶体稳定性。,Chemosphere

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与水铁矿共沉淀的腐殖酸的粒径，电荷和胶体稳定性。
Chemosphere ( IF 8.1 ) Pub Date : 2013-12-10 , DOI: 10.1016/j.chemosphere.2013.10.092
Ruggero Angelico ₁ , Andrea Ceglie ₁ , Ji-Zheng He ₂ , Yu-Rong Liu ₂ , Giuseppe Palumbo ₃ , Claudio Colombo ₃

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腐殖酸（HA）具有胶体特征，其大小和负电荷严格取决于表面官能团。它们能够根据pH和其他环境条件使土壤中大量有序的铁（氢）氧化物络合。因此，在本研究中，我们打算评估与腐殖酸（HA）共沉淀的Fe（II）的胶体性质，以及它们在非生物氧化和Fe（II）和HA的添加顺序下对氢氧化铁结晶度的影响。TEM，XRD和DRS实验表明，Fe-HA的组成由重要的结构变化组成。Fe-HA在酸性pH下的DLS数据显示出双峰尺寸分布，而在非常低的pH下观察到缓慢的聚集过程。电泳zeta电位测量显示Fe-HA大分子具有负表面电荷，为聚集提供强大的静电屏障。在碱性条件下，HA链膨胀，这导致胶体颗粒的稳定性增强。Zeta电位和Fe-HA大分子尺寸的增加反映了两者与pH的线性关系。Fe-HA沉淀物的尺寸和负电荷的增加似乎受酚酸基团电离的影响比受羧酸基团的影响更大。Fe / HA产生负电荷的主要原因是由于在更膨胀的结构中酚基团的解离增加。与水铁矿共沉淀引起的净负表面电位增加，HA构型的相应变化可能触发粒子间聚集，并形成新的负表面。Fe-HA共沉淀可降低静电排斥力，进而可抑制在不同pH值下的聚集过程。因此，预计水铁矿的共沉淀不仅在有机土壤中而且在含有溶解有机物的水中，在碳的稳定和持久性中都将发挥重要作用。

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Particle size, charge and colloidal stability of humic acids coprecipitated with Ferrihydrite.

Humic acids (HA) have a colloidal character whose size and negative charge are strictly dependent on surface functional groups. They are able to complex large amount of poorly ordered iron (hydr)oxides in soil as a function of pH and other environmental conditions. Accordingly, with the present study we intend to assess the colloidal properties of Fe(II) coprecipitated with humic acids (HA) and their effect on Fe hydroxide crystallinity under abiotic oxidation and order of addition of both Fe(II) and HA. TEM, XRD and DRS experiments showed that Fe-HA consisted of Ferrihydrite with important structural variations. DLS data of Fe-HA at acidic pH showed a bimodal size distribution, while at very low pH a slow aggregation process was observed. Electrophoretic zeta-potential measurements revealed a negative surface charge for Fe-HA macromolecules, providing a strong electrostatic barrier against aggregation. Under alkaline conditions HA chains swelled, which resulted in an enhanced stabilization of the colloid particles. The increasing of zeta potential and size of the Fe-HA macromolecules, reflects a linear dependence of both with pH. The increase in the size and negative charge of the Fe-HA precipitate seems to be more affected by the ionization of the phenolic acid groups, than by the carboxylic acid groups. The main cause of negative charge generation of Fe/HA is due to increased dissociation of phenolic groups in more expanded structure. The increased net negative surface potential induced by coprecipitation with Ferrihydrite and the correspondent changes in configuration of the HA could trigger the inter-particle aggregation with the formation of new negative surface. The Fe-HA coprecipitation can reduce electrosteric repulsive forces, which in turn may inhibit the aggregation process at different pH. Therefore, coprecipitation of Ferrihydrite would be expected to play an important role in the carbon stabilization and persistence not only in organic soils, but also in waters containing dissolved organic matter.

更新日期：2019-11-01

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