Extraction of Heavy Metals by Amines Adsorbed onto Silica Gel

Abstract

Previous work has established the possibility of using known coordinating agents supported on silica gel in the removal of heavy metals such as lead, copper, cadmium, and nickel from aqueous media. Functionalized silica gel has been used in the removal of heavy metals with notable success. Silica gel is currently being used as a support for various monofunctional aliphatic amines as coordinating ligands. The current study reports the results of an investigation involving the use of saturated, straight chain primary amines as coordinating ligands in the removal of copper(II), cadmium(II), lead(II), nickel(II), and silver(I) ions from aqueous solutions of known concentration. Primary amines used in this investigation were n-butylamine, n-hexylamine, n-octylamine, n-decylamine, and n-hexadecylamine.

Chemical role of amines in the colloidal synthesis of CdSe quantum dots and their luminescence properties

“…For the former function, the diffusion rate of the Cd-amine complex, which depends on the molecular weight and the stereochemical shape of the amines, played an important role in affecting the size of the product CdSe QDs. In the present study, we did not obtain any evidence for the Cd complexing with amines, however, the presence of the Cdamine complexes is very reasonable by taking the amines used as coordinating agents for the removal of the cadmium metal into consideration [15]. For the latter function, the two major factors of the capping density and the electron donation ability were important factors for passivating the surface defects.…”

“…The effects of the alkylamines in the reaction solution were investigated by Meulenberg et al [14] from the viewpoint of the packing density on the CdSe surface of the alkylamine passivant. Taking the amines as coordinating agents in the removal of cadmium metal into consideration [15], the alkylamines in the solution should behave not only as capping ligands, but also complex ligands in the source solution. Therefore, the chemical role of the amines affecting the luminescence properties, such as wavelength and intensity, must have been studied from the viewpoint of both the complex ligands in the source solution and the capping ligands in the product colloidal solution.…”

Synthesis of nanostructured cadmium and zinc sulfides in aqueous solutions of hyperbranched polyethyleneimine

“…By analogy to the role of alkyl amines [34][35][36][37][38][39][40] in the colloidal synthesis of nanosized transition metal compounds, a possible explanation of the dependence of morphology and size of CdS and ZnS nanostructures on the PEI concentration in the reaction mixture could be due to the role of PEI as a complexing ligand in the source solutions and as a capping agent in the colloidal suspensions of the early formed nanoparticles. Recently, this has been successfully applied to the synthesis of ZnO nanorods, and the control of their arrays, by adding PEI to the source solutions [40].…”

“…Amines can act as ligands and form co-ordination bonds to transition metal ions [34][35][36][37][38][39]. This way, they have an important role in the colloidal synthesis of nanoparticles of transition metal compounds for their behavior as capping ligands on the surface of the early formed nanoparticles [34,35].…”

Sorption of silver ion from aqueous solutions using conducting electroactive polymers

“…Different treatment techniques (adsorption, extraction, ionexchange resins, reverse osmosis, metal replacement, precipitation, electrolysis and electrodialysis) have been developed for removal of silver ions from wastewaters [6][7][8][9][10][11][12][13][14]. Thus, there is a need for introducing an efficient method for the removal or recovery of silver ion from waste solutions generated from the mentioned industries due to the both economical and environmental points of view.…”