Amine/acid catalyzed synthesis of a new silica-aminomethyl pyridine material as a selective adsorbent of copper

Abstract

A novel silica-supported 2-aminomethyl pyridine adsorbent was synthesized using a post-grafting route. This synthetic route involved the reaction of 2-aminomethyl pyridine (AMP) with γ-chloropropyltrimethoxysilane (CPTS) prior to immobilization on the silica support. Based on the extensive evidences that amines and acids can play an important role in silanization as an activator, meglumine and a mixture of hydrochloric acid and ethanol were utilized as a gentle but effective catalyst. Accordingly, three different synthetic pathways were investigated and the catalysis mechanisms of the amine and/or acid were discussed in detail. The synthesized silica-supported 2-aminomethyl pyridine adsorbent under both amine and acid catalyzed conditions was abbreviated as Si-AMP-M-H and characterized, its adsorption properties of Cu²⁺, Ni²⁺ and Co²⁺ were also studied. The adsorption capacity of Si-AMP-M-H for Cu²⁺ is comparable to commercial silica-supported AMP adsorbent. And the possible adsorption mechanism of Cu²⁺ onto Si-AMP-M-H is discussed. Moreover, Si-AMP-M-H shows a favorable selectivity for Cu²⁺ in simulated cobalt electrolyte solution in the presence of nickel. Adsorbed Si-AMP-M-H can be readily regenerated by acid-ammonia treatment. The results suggest that the Si-AMP-M-H prepared here could be promising for cobalt hydrometallurgical purification processes.