Preparation of iron tailings-based porous ceramsite and its application to lead adsorption: Characteristic and mechanism

The reuse and recycling of bulk solid waste, such as tailings, presents a challenge to achieving sustainability in contemporary urban development. In this study, adopting the “waste for waste” approach, a novel form of ceramsite was devised utilizing iron tailings and coal gangue to adsorb Pb(II) from the groundwater environment. The optimized ceramsite, sintered at 850 ℃ with the addition of 30 % coal gangue, exhibited good adsorption potential and environmental friendliness. The optimized ceramsite was a viable material for efficiently removing Pb(II) within the acidic pH range (Qe = 12.28 mg/g). The outcomes from batch experiments and various characterizations of the materials revealed that the adsorption mechanisms of ceramsite involved both physical and chemical adsorption, with chemisorption being the most significant. Column studies showed that ceramsite as fillers could be effective in treating lead discharges from groundwater during mining utilization. The dynamic reaction process of the ceramsite exhibited the most accurate fit with the Thomas and Yan models. The primary adsorption mechanisms included the ceramsite's abundant pores facilitating cation exchange, attraction of Pb(II) to the anionic groups on the ceramsite resulting in its deposition and coverage on the particle surface, and the formation of stable Pb-O and Si-O-Pb bonds. These findings indicate that ceramsite prepared from iron tailings and coal gangue shows promise as an adsorbent for treating lead-containing wastewater.