In order to increase the affinity of the halloysite mineral to 3d-metal ions, its surface was functionalized with N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. A significant influence of the nature of the solvent and silane concentration on the degree of functionalization of halloysite was revealed. According to the data of elemental analysis, FTIR spectroscopy, and thermogravimetry, it was found that the most efficient solvents were tetrahydrofuran and acetonitrile at an equimolar silane to halloysite ratio. The functionalization of halloysite with N-(2-aminoethyl)-3-aminopropylsilyl groups significantly increases the sorption capacity of the material in comparison with both unmodified halloysite and halloysite functionalized with non-chelating 3-aminopropylsilyl groups.