Hexavalent chromium (Cr(VI)) removal by ball-milled iron-sulfur @biochar based on P-recovery: Enhancement effect and synergy mechanism

• Published in: Bioresource technology 2023-03, Vol.371, p.128598, Article 128598
• Main Authors: Ai, Dan, Tang, Yani, Yang, Ruiming, Meng, Yang, Wei, Taiqing, Wang, Bo
• Format: Article
• Language: English
• Subjects: Adsorption; Ball-milled biochar; Charcoal - chemistry; Chromium - chemistry; Cr(VI) removal; Enhancement effect; Iron - chemistry; Phosphorus recovery; Synergy; Water Pollutants, Chemical - chemistry
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2023.128598

[Display omitted] •The iron-sulfur biochar and its recovered phosphate act synergistically on Cr(VI) adsorption.•Recovered phosphorus influenced the pore structure of iron-sulfur biochar significantly.•The uptake mechanisms included physical adsorption, electrostatic attraction and precipitation.•Sustainable strategies to prevent eutrophication, mitigate P crisis and enhance Cr(VI) removal. After the biochar recovery of phosphorus (P), its role in eliminating Cr(VI) is uncertain. In this study, the iron-sulfur biochar (Fe/S@BC) was made by grinding Fe0, S0, and biochar with a ball mill. P-loaded iron-sulfur biochar (P-Fe/S@BC) was produced after recovering P from simulated wastewater and then used to remove Cr(VI) contamination in waterbodies. P-Fe/S@BC got a rich pore structure and more reactive sites through P-recovery. The experiments revealed that P-Fe/S@BC had an enhancement effect on Cr(VI) pollution with removal efficiencies of 76.9 % ∼ 99.4 %, all greater than Fe/S@BC (58.2 %). In particular, 25P-Fe/S@BC (with 6.55 mg P/g) had the most significant advantage. The combination of physical adsorption, electrostatic attraction, and precipitation contributed to Cr(VI) removal. This is an efficient strategy for reusing Fe/S@BC followed by P-recovery, intending to improve the Cr(VI) removal effect and achieve the sustainable use of P resources and wastes.