resource-recycling-red-soil-to-synthesize-fe2o3fau-type-zeolite

Resource Recycling of Red Soil to Synthesize Fe<sub>2</sub>O<sub>3</sub>/FAU-type Zeolite Composite Material for Heavy Metal Removal

Heavy metal-polluted water is of great concern to human health and the eco-environment. In situ water remediation techniques enabled by highly efficient ...

Southern University of Science and Technology

The hazardous red mud (RM) with high As/F mobility and heavy metal contaminated soil have constituted severe environmental threats. This work demonstrates a "waste to eco-material" strategy through a reliable and low-cost protonation approach to eliminate the As/F leaching risk of RM, and then recycle it as heavy metal passivators for Pb/As polluted soil remediation. The As/F anions have been immobilized by the protonated Fe/Al (hydr)oxides within RM via the formation of stable As/F compounds during the protonation process, which satisfies the requirement by the World Health Organization (As leaching <0.01 mg/L; F leaching <0.8 mg/L). Moreover, in the oilseed rape pot experiments, by adding 30 g/kg stabilized RM into Pb/As polluted soils (100 ~ 300 ppm), benefited from its large adsorption capacity, approximately 40.9 ~ 49.7% Pb and 40.8 ~ 54.8% As concentrations in the plant are reduced without adverse effects. The whole process for RM treatment and soil remediation is cost-effective, straightforward and eco-friendly without secondary pollution or soil degradation. This research provides a green chemical strategy to address both RM recycling and heavy metal contaminated soil remediation problems, which shows high economic feasibility and ecological benefits.

Protonation stabilized high As/F mobility red mud for Pb/As polluted soil remediation.

Due to the large output and potential ecological risks, disposal of engineering abandoned soils (EAS) has become an enormous challenge for human society. Herein, EAS has been transformed into microporous analcime (ANA) zeolite material through a fast, energy-efficient, and straightforward conversion process. The as-synthesized ANA has been employed to remediate Cu-polluted soil, which shows a significant ecological restoration function in a vegetable pot experiment. With 25 g/kg ANA into Cu contaminated soil (total Cu concentration: 200 ppm), the Cu accumulation concentration in vegetables has been decreased from 5.60 down to 1.80 mg/kg (approaching the background Cu level 1.70 mg/kg in vegetables). Detailed mechanism study combining with DFT calculations reveals that the Cu in soil has been captured both inside the ANA pore channels and on the surface via ion-exchange and surface adsorption mechanism. The whole process, including ANA synthesis and Cu polluted soil remediation, has been optimized to show a valuable conceptual model to recycle EAS resource and in-situ remediate Cu polluted soil.

Remediation of Cu-polluted soil with analcime synthesized from engineering abandoned soils through green chemistry approaches.

Herein, a novel "waste reclamation for soil remediation" strategy has been developed for both alkaline waste red mud (RM) recycling and heavy metal (HM) polluted soil remediation. Through a direct one-pot hydrothermal reaction process, the Al, Si, alkali, and FeO components in waste RM have been transferred into ferric oxide decorated ANA-type zeolite (FeO-ANA). As tested by the HMs polluted soil remediation and oilseed rape planting experiment, when 25 g/kg FeO-ANA is added into the Pb, Cu, Cr and anionic AsO polluted soil (HM concentration: 100-200 mg/kg), it can effectively suppress the HMs mobility in soil and reduce the bio-accumulation concentrations of HMs in the harvested oilseed rape (reduce ratio: 37.9-69.5%). The detailed mechanism study using energy dispersive X-ray energy spectroscopy, in-depth X-ray photoelectron spectroscopy and density function theory calculation concludes that the Cu, Pb and Cr in soil have been adsorbed and trapped in the framework structure of ANA in FeO-ANA mainly via the cation exchange process. While the anionic AsO species are mainly caught by the FeO component in FeO-ANA via surface adsorption. Overall, this work firstly transforms waste RM into FeO-ANA for soil remediation, which is valuable to waste resource recycling and environmental conservation.

Zheting Chu

Southern University of Science and Technology

Resource Recycling of Red Soil to Synthesize Fe₂O₃/FAU-type Zeolite Composite Material for Heavy Metal Removal

Zheting Chu

Southern University of Science and Technology

Resource Recycling of Red Soil to Synthesize Fe2O3/FAU-type Zeolite Composite Material for Heavy Metal Removal

Resource Recycling of Red Soil to Synthesize Fe₂O₃/FAU-type Zeolite Composite Material for Heavy Metal Removal