Covalent organic frameworks constructed by flexible alkyl amines for efficient gold recovery from leaching solution of e-waste

[Display omitted] •Triformylphloroglucinol and thiosemicarbazide as precursors for synthesizing TpTsc.•TpTsc with excellent adsorption capacity of gold shows higher than most adsorbents.•Dual functions of adsorption and reduction enhance gold adsorption capacity of TpTsc.•TpTsc can selectively extract gold from real electronic waste liquids. Recovering precious metals from electronic equipment waste involves significant environmental and economic benefits. In this paper, a covalent organic framework, named as TpTsc COF, was synthesized by using flexible alkyl amine thiosemicarbazide (Tsc) and 1,3,5-triformylphloroglucinol (Tp) as precursors for extracting gold from actual electronic waste. The results show that it has favorable selectivity, high recycling and groundbreaking adsorption capacity (4400.23 mg g−1). Such excellent adsorption capacity can be attributed to the improved crystallinity by irreversible enol-to-tautomerism of Tp, the abundant functional group sites in Tsc, and the efficient reduction of gold by thiourea. The adsorption process can be well fitted with the pseudo-second-order kinetic model and Langmuir mode, which is characterized by the coordination between Au (III) and S, N, O atoms in COF, as well as the electrostatic interaction between protonated amino groups and AuCl4− in acidic system. The advantages of this feasible method facilitate effective gold recovery from low-cost electronic waste.