Laboratory of Separation and Reaction Engineering-Laboratory of Catalysis and Materials (LSRE-LCM), Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465, Porto, Portugal.
Instituto de Química, Universidade Federal de Mato Grosso do Sul, Av. Senador Filinto Muller, 1555, CP 549, Campo Grande, MS, 79074-460, Brazil.
Environ Sci Pollut Res Int. 2018 Oct;25(28):27783-27795. doi: 10.1007/s11356-018-1561-x. Epub 2018 Mar 15.
The mineralization of bio-recalcitrant humic acids (HAs) by a solar photo-Fenton (SPF) process was investigated in aqueous system, in order to understand its abatement in real high-HA content matrices, such as sanitary landfill leachates. SPF reactions were performed in tubular photoreactors with CPCs at lab-scale (simulated solar light) and pilot-scale (natural sunlight). Considering the experimental conditions selected for this work, the formation of insoluble HA-Fe complexes was observed. Thus, to avoid HA precipitation, oxalic acid (Ox) was added, since Fe-Ox complexes present a higher stability constant. The effect of different process variables on the performance of SPF reaction mediated by ferrioxalate complexes (SPFF) was assessed with excess of HO (50-250 mg L), at lab-scale: (i) pH (2.8-4.0); (ii) initial iron concentration (20-60 mg Fe L); (iii) iron-oxalate molar ratio (Fe-Ox of 1:3 and 1:6); (iv) temperature (20-40 °C); (v) UV irradiance (21-58 W m); and (vi) commercial-HA concentration (50-200 mg C L). At the best lab conditions (40 mg Fe L, pH 2.8, 30 °C, 1.6 Fe-Ox molar ratio, 41 W m), commercial HAs' mineralization profile was also compared with HAs extracted from a sanitary landfill leachate, achieving 88 and 91% of dissolved organic carbon removal, respectively, after 3-h irradiation (8.7 kJ L). Both reactions followed the same trend, although a 2.1-fold increase in the reaction rate was observed for the leachate-HA experiment, due to its lower humification degree. At pilot-scale, under natural sunlight, 95% HA mineralization was obtained, consuming 42 mM of HO and 5.9 kJ L of accumulated UV energy. However, a pre-oxidation during 2.8 kJ L (12 mM HO) was enough to obtain a biodegradability index of 89%, showing the strong feasibility to couple the SPFF process to a downstream biological oxidation, with low chemicals and energetic demands. Graphical abstract ᅟ.
研究了在水体系中通过太阳能光芬顿（SPF）过程对生物难降解腐殖酸（HA）的矿化作用，以便了解其在实际高 HA 含量基质（如卫生填埋渗滤液）中的去除情况。在实验室规模（模拟太阳光）和中试规模（自然阳光）的 CPC 管式光反应器中进行 SPF 反应。考虑到这项工作选择的实验条件，观察到了不溶性 HA-Fe 配合物的形成。因此，为了避免 HA 沉淀，添加了草酸（Ox），因为 Fe-Ox 配合物具有更高的稳定常数。在实验室规模下，评估了不同工艺变量对铁草酸盐配合物介导的 SPF 反应（SPFF）性能的影响：（i）pH（2.8-4.0）；（ii）初始铁浓度（20-60 mg Fe L）；（iii）铁-草酸摩尔比（Fe-Ox 为 1:3 和 1:6）；（iv）温度（20-40°C）；（v）UV 辐照度（21-58 W m）；（vi）商业 HA 浓度（50-200 mg C L）。在最佳实验室条件下（40 mg Fe L、pH 2.8、30°C、1.6 Fe-Ox 摩尔比、41 W m），还比较了商业 HA 的矿化曲线与从卫生填埋渗滤液中提取的 HA 的矿化曲线，在 3 小时照射后分别实现了 88%和 91%的溶解有机碳去除，分别为 8.7 kJ L。这两种反应都遵循相同的趋势，尽管由于腐殖化程度较低，渗滤液-HA 实验的反应速率提高了 2.1 倍。在中试规模下，在自然阳光下，HA 矿化率达到 95%，消耗 42 mM 的 HO 和 5.9 kJ L 的累积 UV 能量。然而，预氧化 2.8 kJ L（12 mM HO）就足以获得 89%的生物降解指数，表明将 SPFF 工艺与下游生物氧化相结合具有很强的可行性，且对化学品和能量的需求较低。
