Membrane permeation characteristics of methanesulfonic acid and tin methanesulfonate were examined in diffusion dialysis and electrodialysis with ion-exchange membranes. In the diffusion dialysis experiments, the methanesulfonic acid permeated through an anion-exchange membrane, but did not permeated through a cation-exchange membrane. The apparent diffusivities of methanesulfonic acid through the anion-exchange membrane were determined with the flux of methanesulfonic acid and the concentration difference between the compartments. The values were the same order of hydrochloric acid permeation in the anion-exchange membrane. In the experiment of electrodialysis for tin methanesulfonate solution, methanesulfonic acid moved to the anode-side strip compartment through the anion-exchange membrane, but tin ion moved to the cathode-side strip compartment through the cation-exchange membrane. These fluxes were almost proportional to the current density, and the flux of tin ion agreed with the theoretical value corresponding to that di-charged ion permeates at the transport number equal to unity.
Generally speaking, wastewater generated during the metallurgical process for recovering precious metals, includes various precious metals such as Au, Pt, Pd, Ag, the concentration of which is about 10 mg/L, as well as other metals such as Cu, Fe, the concentration of which varies from several mg/L to more than 10,000 mg/L. However, the most of these valuable elements are not recovered, due to a relatively high processing cost as well as various technical problems. It should be noted that the concentration of metals in wastewater is as high as their concentration in ores. Taking into account these facts, authors are putting forward a new process, which consisting of neutralization/reduction, precipitation and fusion. The idea was to recover and recycle Au, Ag, Pd metals at a recovery higher than 90% as well as protecting the environment by saving the resources.
In this study, the mechanical properties and morphological change of polyethylene terephthalate (PET)/medium density polyethylene (MDPE) blends with/without compatibilizers were investigated upon heat-treatment cycling. The compatibilizer, which consists of ethylene-glycidyl methacrylate (EGMA) as a main chain, showed the good mechanical properties. For example, PET/MDPE with EGMA compatibilizer blend had the higher elongation at breaking (~800%) in comparison with the PET/MDPE without compatibilizer (neat PET/MDPE). Although the value of the elongation at break of PET/MDPE with/without EGMA compatibilizer decreased upon heat-treatment cycling, the PET/MDPE with 3wt%~5wt% EGMA compatibilizer still showed the high elongation at break at the second heat-treatment cycle and after the third cycle. This result shows the possibility that the material recycling concerning PET, which is recycled mainly one time, can be substantially done two times or more, and an increase of the heat-treatment cycling number means that the gross weight of present PET waste and PE waste can be greatly decreased. In order to compare the morphological change of the PET/MDPE with/without compatibilizer, scanning electron microscope observation was carried out. As a result, when adding the EGMA compatibilizer into the PET/MDPE, the size of the PE phase was smaller than that of neat PET/MDPE. Moreover, after several heat-treatment cycles, the morphological change was not be observed for the PET/MDPE with EGMA compatibilizer. From these results, it would be deduced that EGMA can react with the end-groups of PET during heat-treatment, so that the mechanical properties and morphological change of PET/PE composites can not be observed.