ZnFe-LDH synthesized by seed-induced method to simultaneous enhance arsenic removal, stabilization and sludge reduction

• Published in: Journal of hazardous materials 2024-12, Vol.480, p.136459, Article 136459
• Main Authors: Shi, Miao, Zhou, Zeyan, Li, Qingzhu, Liao, Qi, Yang, Weichun, Si, Mengying, Yang, Zhihui, Wang, Qingwei
• Format: Article
• Language: English
• Subjects: Arsenic stabilization; Seed-induced method; Sludge reduction; ZnFe-LDH
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2024.136459

To simultaneously enhance arsenic removal, stabilization and sludge reduction, a seed-induced method was applied to in-stiu synthesize ZnFe-LDH containing arsenic (ZnFe-As-LDH). The optimal seed was determined to be ZnFe-LDH by analyzing the effects of the unseeded system and seed-induced system (FeⅡFeⅢ-LDH, ferrihydrite and ZnFe-LDH). In the ZnFe-LDH seed system, the arsenic removal efficiency increased and the arsenic leaching concentration were drastically reduced by 91.33 % under the optimal conditions as the seeds dosage of 2.5 g/L, pH 10 and Zn/Fe ratio of 1.5. The addition of seed crystals promoted crystal growth and aggregation and finally regulated the formation of dense bulk LDH with fewer pores and smaller pore sizes. The arsenic removal and stabilization were achieved by converting active arsenic into more stable crystalline bound arsenic through coprecipitation, ion exchange and complexation. The SV30 was reduced by 73.68 % and it was due to reduction of unstable surface water and interspace and crystallinity enhancement. The formation pathway of ZnFe-As-LDH by seed-induced was elucidated. The seed-induced method promoted the formation of arsenic-containing ferrihydrite and Zn(OH)2 coprecipitations on the surface of ZnFe-LDH seed, and led to a structural rearrangement to generate ZnFe-As-LDH. [Display omitted] •Arsenic leaching concentration is reduced by 91.33 % by seed-induced method.•The SV30 and water content are reduced by 73.68 % and 37.81 %, respectively.•ZnFe-As-LDH is formed to stabilize arsenic by phase transformation.•The intermediation is arsenic-containing ferrihydrite and Zn(OH)2 coprecipitation.