Abstract

In this study, milli polyurethane (milli PU) was functionalized for use in the sequential recovery of precious and toxic metals from electronic waste (mobile boards) as a solution containing a mixture of metals and elements. For this purpose, graphene oxide (GO), polyethylene imine-dopamine, and dithiocarbamate were used to create functional groups on the outer surface of the milli PU. Scanning Electron Microscope (SEM) was used to evaluate the morphology and activation of milli PU sites and to examine the characteristics of the cavities after exposure to acidic solutions during functionalization steps. Raw and functional milli PU's functional groups were evaluated using Fourier Transform Infrared Spectrometer (FTIR). The results showed that the cavities in functionalized milli PU were 100-200 mu m in size and the changes in the surface to volume ratio were appropriate. Also, the N-H bond was related to the first type of amine in 3297.26 cm(-1), and double bond C=N in 1640.5 cm(-1) was specified. Due to double bond existence and its activation, this factor can bond with other elements, including metals. Sulfonic bonds (S=O) at 1337 cm(-1) indicate the presence of sulfur bases combined with alkyl and aryl, which can bond with OH, which eventually converts to sulfonic acid. Under these conditions, the exchange of metal ions by the sulfonic base is also expected. Given the presence of such bands in the FTIR spectrum obtained from raw polyurethane (PU), it can be concluded that PU functionalization has been performed properly. Metals can bind to existing functional groups that form the solid-metal phase complex (MS), which is very effective in removing it from the aqueous solution, and the process of metal recovery and complex formation with them is maintained to the desired level. Open cavities and high porosity, especially in functionalized PU samples, are well illustrated by electron imagery, which provides a high level of metal recovery.