Abstract
Pickling bath sludge, classified as a hazardous waste, is disposed of by landfill for decades. This study explores its resource utilization as an adsorbent material. The sludge primarily comprises FeF₃‧2H2O and Cr or Ni or Fe-bearing spinels. A multi-step processing strategy was developed: FeF₃ was first removed by NaOH washing to effectively recover F⁻, followed by HCl leaching to generate a Fe-rich solution and a spinel-enriched residue. Direct hydrothermal treatment of the raw sludge and leaching residues with sodium sulfide at 160oC for 6h produced particles with low oxytetracycline (OTC) adsorption capacity (<250 mg/g). Conversely, the acid leachate (containing ~20 g/L Fe) was hydrothermally treated to synthesize erdite particles, which exhibited significantly higher OTC adsorption capacity (~2000 mg/g), approximately ten times greater than materials derived from the untreated sludge or residues. Mechanistic studies revealed that erdite undergoes spontaneous hydrolysis in aqueous solution to form Fe–S flocs with abundant sulfhydryl and hydroxyl groups, enabling strong coordination with OTC molecules. This work demonstrates a sustainable approach for converting pickling bath sludge into a high-performance adsorbent, offering both environmental remediation and sustainable waste management. Therefore, the OTC degrading bacterial candidate can be used on the surface of the constructed adsorbent for enhancing OTC adsorption.
Keywords:
- Keyword: pickling bath sludge; waste reutilization; adsorbent; wastewater treatment; sustainability.
How to Cite:
Yang, D., Lan, X., Luo, W., Liu, J., Qin, W., Rahman, M. S., Zhu, S. & Chen, Y., (2026) “Sustainable Resource Recycling of Pickling Bath Sludge into a High-Performance Erdite Adsorbent for Oxytetracycline Removal”, Journal of Intelligent and Sustainable Systems (JISS) 2(2).