Sulfidated nanoscale zero-valent iron derived from iron sludge for tetracycline removal: Role of sulfur and iron in reactivity and mechanisms.
Environ Pollut
; 344: 123305, 2024 Mar 01.
Article
em En
| MEDLINE
| ID: mdl-38195022
ABSTRACT
Iron sludge, produced during the drinking water treatment process, can be recycled as potential iron resource to create environmental functional material. In this study, sulfur-iron composites derived from iron sludge (S-Fe composites) was synthesized through sulfidation and carbonization, and used for the tetracycline (TC) removal under aerobic and anoxic conditions. The reactivities of these as-prepared products were strongly depended on pyrolysis temperatures. In particular, sulfidated nanoscale zero-valent iron loaded on carbon (S-nFe0@CIS) carbonized at 800 °C exhibited the highest TC removal efficiency with 86.6% within 30 min at circumneutral pH compared with other S-Fe composites. The crystalline structure of α-Fe0, FeSx and S0 as main active sites in S-nFe0@CIS promoted the degradation of TC. Moreover, the Fe/S molar ratios significantly affected the TC removal rates, which reached the best value as the optimal S/Fe of 0.27. The results illustrated that the optimized extent of sulfidation could facilitate electron transfer from nFe0 towards contaminants and accelerate Fe(III)/Fe(II) cycle in reaction system compared to bared nFe0@CIS. We revealed that removal of TC by S-nFe0@CIS in the presence of dissolved oxygen (DO) is mainly attributed to oxidation, adsorption and reduction pathways. Their contribution to TC removal were 31.6%, 25.2% and 28.8%, respectively. Furthermore, this adsorption-oxygenation with the formation of S-nFe0@CIS-TC* complexes was a surface-mediated process, in which DO was transformed by the structural FeSx on complex surface to â¢OH with the generation of H2O2 intermediate. The intermediates of TC and toxicity analysis indicate that less toxicity products generated through degradation process. This study provides a new reclamation of iron sludge and offers a new insight into the TC removal by S-nFe0@CIS under aerobic conditions.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Esgotos
/
Poluentes Químicos da Água
Idioma:
En
Ano de publicação:
2024
Tipo de documento:
Article