Abstract

Rapid and safe treatment of harvested fresh biomass of hyperaccumulators is essential for phytoremediation of metal-contaminated soils. Here, an electro-Fenton (EF) process was used to remove cadmium (Cd) and chemical oxidation demand (COD) from waste liquor from the dewatering of biomass of the hyperaccumulator Sedum plumbizincicola after flocculation precipitation. The results showed that the order of impact of the factors on the removal rate of COD and Cd was pH > electrical current density > H₂O₂ dosage. Increasing pH promoted Cd removal but hindered COD removal. As current density and H₂O₂ dosage increased the removal rates of both Cd and COD initially increased and then decreased. Compared to an electrocoagulation process, the addition of H₂O₂ in EF process greatly enhanced Cd and zinc (Zn) removal. Speciation analysis showed that most of the Cd and Zn in the initial liquor were organically and inorganically complexed. At optimal conditions, e.g., pH 5, current density 15 mA cm⁻² and H₂O₂ dosage 9 g L⁻¹, the removal efficiencies of Cd, Zn and COD reached 99.4, 99.9 and 55.5% after 80 min of EF treatment. Electro-Fenton process can therefore be used to quickly remove trace metals from the waste liquor of the hyperaccumulator.

摘要

快速安全地处理超级蓄积器中收获的新鲜生物质对于金属污染土壤的植物修复至关重要。在这里，采用电芬顿（EF）工艺在絮凝沉淀后通过对超级蓄积景天景天的生物质进行脱水，从废液中去除镉（Cd）和化学氧化需求（COD）。结果表明，这些因素对COD和Cd去除率的影响顺序为pH>电流密度> H ₂ O ₂剂量。pH值的增加促进了Cd的去除，但阻碍了COD的去除。作为电流密度和H ₂ O ₂剂量增加后，Cd和COD的去除率先增加然后降低。与电凝工艺相比，在EF工艺中添加H ₂ O ₂大大提高了Cd和锌（Zn）的去除率。形态分析表明，初始液体中的大多数Cd和Zn是有机和无机络合的。在最佳条件下，例如pH 5，电流密度15 mA cm ^-2和H ₂ O ₂剂量9 g L ^-1，在EF处理80分钟后，Cd，Zn和COD的去除率分别达到99.4、99.9和55.5％。 。因此，可以使用电子芬顿工艺快速去除超级蓄能器废液中的痕量金属。