Laboratori d'Electroquímica dels Materials i del Medi Ambient, Departament de Química Física, Facultat de Química, Universitat de Barcelona, Martí i Franquès 1-11, 08028, Barcelona, Spain.
Departamento de Química, Universidade Federal da Paraíba, João Pessoa, CEP 58.051-900, PB, Brazil.
Chemosphere. 2020 Feb;240:124838. doi: 10.1016/j.chemosphere.2019.124838. Epub 2019 Sep 14.
Modified sodium vermiculite, an iron-rich clay mineral, has been used in novel heterogeneous electrochemical Fenton-based treatments, so-called electro-Fenton (EF)-vermiculite, UVA photoelectro-Fenton (PEF)-vermiculite and solar photoelectro-Fenton (SPEF)-vermiculite. Tests were made with 130 mL of 0.150 mM Ponceau SS diazo dye in 0.050 M NaSO at pH 3.0, in the presence of 1.0 g L catalyst microparticles. The electrolyses were performed in an undivided cell with a boron-doped diamond anode (BDD) and air-diffusion cathode for HO production, at 33.3 mA cm. Decolorization and mineralization were upgraded in the sequence: EF-vermiculite < PEF-vermiculite < SPEF-vermiculite. The removal of organics occurred by the combined action of OH oxidant formed at the BDD surface and homogeneous and heterogeneous Fenton's reactions, along with the photolysis caused by UVA light or sunlight. The homogeneous Fenton's reaction resulted from iron ions leaching, but the heterogeneous mechanism was prevalent. Comparative treatments by anodic oxidation in the presence of HO and homogeneous EF were less effective than EF-vermiculite. The diazo dye absorbance decays agreed with a pseudo-first-order kinetics. SPEF-vermiculite was the most powerful process, yielding total decolorization and 84.1% mineralization after 300 and 360 min, respectively. The influence of catalyst concentration, current density and diazo dye content on PEF-vermiculite performance was examined. Oxalic, oxamic, malic, tartronic and acetic acids were detected as final short-linear carboxylic acids.
改性钠蒙脱石，一种富铁粘土矿物，已被用于新型非均相电化学芬顿（Fenton）处理中，即所谓的电芬顿（EF）-蒙脱石、UVA 光电芬顿（PEF）-蒙脱石和太阳能光电芬顿（SPEF）-蒙脱石。实验采用 130ml 浓度为 0.150mM 的 Ponceau SS 重氮染料，在 0.050M 的 NaSO 中，pH 值为 3.0，催化剂微颗粒浓度为 1.0g/L。在未分隔的电池中进行电解，采用掺硼金刚石阳极（BDD）和空气扩散阴极以产生 HO，电流密度为 33.3mA/cm。脱色和矿化的顺序为：EF-蒙脱石<PEF-蒙脱石<SPEF-蒙脱石。有机物的去除是由 BDD 表面形成的 OH 氧化剂、均相和非均相 Fenton 反应以及 UVA 光或太阳光引起的光解共同作用的结果。均相 Fenton 反应是由铁离子浸出引起的，但非均相机制更为普遍。在存在 HO 的阳极氧化和均相 EF 进行的对比处理不如 EF-蒙脱石有效。重氮染料的吸光度衰减符合准一级动力学。SPEF-蒙脱石是最有效的工艺，在 300 和 360min 后分别达到完全脱色和 84.1%的矿化。考察了催化剂浓度、电流密度和重氮染料含量对 PEF-蒙脱石性能的影响。检测到草酸、氨基乙二酸、苹果酸、酒石酸和乙酸作为最终的短链羧酸。
