Static removal of cadmium from aqueous and nonaqueous matrices by application of layer-by-layer chemical deposition technique

Layer-by-layer (LbL) chemical deposition technique was implemented, for the first time as a novel approach, to study and evaluate the process of static removal of cadmium ion from aqueous and nonaqueous solutions. The proposed method was based on sequential dipping of a glass substrate in an ethanolic solution containing 8-hydroxyquinoline (8HQ), as the selected chelating compound, for the deposition of 8HQ-molecules on the surface followed by dipping in Cd(II) solution for the static deposition of the first layer of Cd(II)–8HQ complex. Several important controlling factors were studied and optimized including the effect of dipping cycles, dipping time, Cd(II) concentration, pH of metal ion solution, exposed surface area, interfering ions and temperature. The potential applications of (LbL) chemical deposition as a promising technique for static removal of Cd(II) from sea and tap water samples as well as organic solvents such as ethanol and acetone were studied and explored. The results of this study were found to prove superior percentage extraction values (99.43–99.86%) for recovery of Cd(II) from the examined matrices.