Investigating the extraction performance and mechanism of a multifunctional thiourea molecule for the effective removal of Ag(i) from aqueous solutions†

Highly efficient and selective extraction of silver ions from wastewater remains a formidable challenge in ensuring public health and protecting ecosystems. Herein, an acyl-based thiourea extractant known as N-benzoyl-N′,N′-dibutyl thiourea (BDBTU) was used for the selective extraction of silver ions from aqueous solution by a solvent extraction method. BDBTU displayed an outstanding extraction efficiency of Ag(I) with an extraction ratio of 96.7% under the optimal extraction conditions, surpassing its effectiveness for Cu(II) and Mn(II) ions. In addition, BDBTU retained high effectiveness even after undergoing eight regeneration cycles, with only a slight decrease in the extraction efficiency from 96.7% to 95.2%. Moreover, it displayed selective extraction towards Ag(I) ions under the interference of metal ions (i.e., Cu(II), Pb(II), Mn(II), Zn(II), Ni(II), Co(II) and Na(I)). The investigation into the extraction mechanism of BDBTU towards Ag(I) unveiled that BDBTU provided a high affinity for Ag(I) accompanied by the formation of Ag–O–C and Ag–S–C bonds. These results indicated that the exceptional extraction stability and selectivity of BDBTU offer promising prospects for diverse applications, highlighting its potential in silver-containing wastewater treatment fields.