Chloride is one of the effective medium in which platinum group metals (PGMs) can be brought into a solution, thus chlorocomplexes are particularly important in the process chemistry of PGMs separations. Rh(III) chlorocomplexes are poorly extracted into organic solvents, which is due to the charge of the complex as well as those inert character in a solution, that is, formation of RhCl_6–n(H₂O)_n^(3–n)– (n = 1–6). The problem of solvent extraction of Rh from chloride solutions has not yet been solved and there is no effective industrial extractant for Rh.

Adding Sn(II) to a Rh(III) feed is a good procedure which can be used to make Rh react more easily to extraction. However, the impurities such as Fe(III) and Al(III) are also leached together from spent automobile catalysts with chloride solutions. Therefore, the investigation of effect of Sn(II) on extraction of Fe(III) and Al(III) as impurities is important for the extraction of Rh from chloride solutions added Sn(II).

In the present study, the effect of Sn(II) on extraction of Fe(III) and Al(III) from chloride solutions contained Sn(II) with tri-n-octylamine (TOA) was investigated for the separation from Rh(III). Al(III) was not extracted with TOA, either with or without Sn(II). Meanwhile, the extraction of Fe(III) decreased with increase in the concentration of Sn(II) and the separation of Rh(III) from Fe(III) was possible by concentrating Rh(III) and Sn(II) in the organic pahse.

Recently, the demand for LED light bulbs is rapidly increasing due to an increasing demand for energy saving lightning options. In this work, the elemental composition of LED light bulbs is first analyzed, and then a flowsheet for recovering LED chips and other valuable metals from spent LED light bulbs is put forward. The suggested flowsheet includes eddy current separation (ECS) and air tabling, in addition to several refining processes. The experimental results indicated that the eddy current separation and the air tabling are useful techniques for sorting components of LED bulbs, enabling the recycling of aluminium, plastics, and precious metals, such as gold and silver. Next, five different scenarios for treatment of spent LED light bulbs were considered and a combined life cycle assessment (LCA) and cost-benefit analysis was carried out to find out the most suitable alternative. The results of the combined assessment suggested that the recycling of mainly Al and plastics from spent LED bulbs is an environmentally friendly and cost-effective alternative.

Mg-Fe composite oxides with various mixing ratios were synthesized at different calcination temperature, to use them as anion removal agents. Crystal structure and specific surface area of the Mg-Fe composite oxides were evaluated. The B and As(III) removal tests from dilute aqueous solution (initial concentration: 20 mg/dm³) were conducted by using the Mg-Fe composite oxides. The predominant factors for removing them efficiently were considered.

The Mg-Fe composite oxides having various specific surface area and different crystal structure are obtained, depending on the chemical composition and the calcination temperature. When the mixing ratios are set to Mg:Fe = 1:1, 2:1 and 3:1, respectively, Mg-Fe type LDH is mainly formed as a precursor before calcination. Amorphous composite oxide is obtained by the calcination of Mg-Fe type LDH at 400°C. Approximately, the specific surface area of Mg-Fe composite oxides is increasing with an increase in the mixing ratio of Fe. On the other hand, the specific surface area of them also tends to decrease as the calcination temperature increases over 600°C.

As the B removal mechanism from dilute aqueous solution, it is considered that (1) the formation of Mg(OH)₂ on the particle surface by the hydration of Mg-Fe composite oxides during removal operation and (2) the reconstruction of LDH structure by the partial hydration of Mg-Fe composite oxides are predominant. It is also found that (1) the hydration on the surface of MgO particles, (2) the reconstruction of LDH structure by the partial hydration, (3) the affinity with As(III) due to Fe and (4) the high specific surface area are effective for the As(III) removal.