Catalyst synthesis and application in oxidation assays

Hydrocarbons contaminated soil remediation is a critical issue since soil is a complex media, mainly because of its heterogeneity. Thereby literature lacks studies involving in situ chemical oxidation focusing on soil remediation. Clays can be an important proposal as support to heterogeneous catalyst for oxidation process, due to their natural abundance and eco-friendly characteristic. Different clay-based catalysts were synthesized through 23 experimental design varying sodium hydroxide (NaOH), ferrous sulfate (FeSO4) and ferric sulfate (Fe3(SO4)2) concentrations. A set of different synthesized catalysts were applied in phenanthrene (PHE) contaminated soil oxidation to evaluate the activation of the sodium persulfate (SP) and hydrogen peroxide (HP) oxidants. Values of PHE removal from contaminated soil were used as response. At the experimental conditions studied, most of the produced catalysts proved to be efficient in activating both oxidants, achieving around 80% of PHE removal from soil. Control assays presented that around 20% of PHE can be naturally transferred to liquid phase and PHE removals from soil did not occur during oxidation without clay modification, i.e., using raw clay. The selected catalyst obtained the best oxidant activation with NaOH concentration of 0.625 M, ferrous sulfate concentration of 137.25 gL-1 and ferric sulfate concentration of 274.50 gL-1

烃类污染土壤的修复是一项至关重要的任务，鉴于土壤作为一种复杂的介质，其异质性尤为显著。因此，在土壤修复领域，关于原位化学氧化的研究文献尚显匮乏。鉴于粘土资源丰富且具有环保特性，其可作为一种重要的载体，用于氧化过程中的异相催化剂。通过23种实验设计，研究了不同浓度的氢氧化钠（NaOH）、硫酸亚铁（FeSO4）和硫酸铁（Fe3(SO4)2）对粘土基催化剂的合成影响。一系列不同合成的催化剂被应用于苯并[a]芘（PHE）污染土壤的氧化过程，以评估过硫酸钠（SP）和过氧化氢（HP）氧化剂的活化效果。以污染土壤中PHE的去除率作为响应值。在所研究的实验条件下，大部分制备的催化剂在活化两种氧化剂方面均表现出高效性，实现了土壤中约80%的PHE去除。对照实验结果表明，约20%的PHE可以自然迁移至液相，而在未对粘土进行改性（即使用未经处理的粘土）的情况下，氧化过程中土壤中的PHE去除并未发生。在氢氧化钠浓度为0.625 M、硫酸亚铁浓度为137.25 gL-1和硫酸铁浓度为274.50 gL-1的条件下，所选催化剂实现了最佳的氧化剂活化效果。