Solvent extraction is one of the common methods for the recovery of boric acid (or boron) from aqueous solutions. A wide variety of different compounds including monohydric alcohols has been tested, and there is wide recognition that they are rather ineffective compared to other extractants such as diols. Nevertheless, monohydric alcohols find application in industrial processes, demonstrating their efficiency. The intention of this study is to clarify this discrepancy and to provide an overall picture of monohydric alcohols as an extractant for boric acid. Five different monohydric alcohols are the object of this study: n-octanol, 2-ethyl-1-hexanol, 2-butyl-1-octanol, 2-octanol and 3,7-dimethyl-3-octanol. A special focus of this work is the examination of the effect of the structure of the carbon chain and the effect of the composition of the aqueous phase on the extraction efficiency. As well as the extraction efficiency for boric acid, other important properties are examined such as the viscosity of the organic phase, the solubility of alcohols in the aqueous phase and the co-extraction of salts used as a salting-out agent (NaCl, Na2SO4, MgCl2, LiCl, LiNO3). Finally, a numerical algorithm is developed to calculate the relationship between the number of theoretical stages and the phase ratio at equilibrium for selected extraction systems.

Due to its low density, high specific strength, and resource availability, magnesium and its alloys, such as AZ91, have a high potential for various lightweight applications. [1][2][3] A major hindrance for its widespread processing and use is its high reactivity, contributing to high dross-and sludge formation in the melt, which results in the metal being prone to corrosion and containing high quantities of nonmetallic inclusions, if the handling of the melt has not been accurate. The inclusions can be divided into oxide films, lumps, and clusters, as well as intermetallic particles; gas-and shrinkage pores, may also be present. [1][2][3][4][5] While measures are taken to protect and cleanse magnesium melts on industrial scale, such as gas purging treatments by Ar, N 2 , or Cl 2 , the usage of a variety of possible cover gases or fluxes and the optimization of the casting system toward a high grade of enclosure, [1,6] the application of ceramic foam filters is seen as a promising method for cleansing the melt and improving the mechanical properties of the casting. [7][8][9] Ideally, an auxiliary addition of fluxes would be avoided, while delivering the same quality of melt cleanliness. [10][11][12] Wu et al. emphasized the effectiveness of ceramic foam filters made from MgO or Al 2 O 3 in AZ91, improving the elongation-to-failure of cast samples up to relative 58%. [13] In contrast to oxidic, sintered filters, carbon-bonded ceramic foam filters show higher resistance toward thermal shock and creep deformation, as well as lower energy consumption during their manufacture, due to their lower manufacturing temperature. [14] After carbon-bonded alumina filters showed promising results in the filtration of steel melts, [15] short-term immersion tests in AZ91 have been carried out to evaluate their applicability in a magnesium alloy melt. Interface reactions between the AZ91 melt and variously coated ceramic Al 2 O 3 -C filters have been investigated after immersion times of 10-120 s. [16] The investigated filter coatings consisted of Al 2 O 3 , MgO-C, MgAl 2 O 4 , or carbon nanotubes/ alumina nanosheets. The formation of MgO in situ layers was shown on filter surfaces containing Al 2 O 3 or MgAl 2 O 4 . [16] Therefore, the next step toward assessing the applicability of oxidic as well as carbon-bonded ceramic foam filters in the field of magnesium melt filtration is the evaluation of their long-term resistance toward the magnesium melt, with a special regard toward melt contamination and inclusion content.In this study, additional ceramic foam filter materials, namely ZrO 2 [13] and MgAlON, [17] were added to the selected materials

The rapid development of light-emitting-diode (LED) technology is attributed to its superiority over light sources of earlier generations. Although LED lamps, compared to compact fluorescent lamps, are considered less harmful to the environment, there is still no efficient solution to deal with them at the end of their lifecycle. The first part of the study provides a detailed characterisation of LED lamps, focusing on their most interesting component: the LED module. LED packages attached to the module are highly enriched with Ga, In, Pd, Ag, Au, Sr, Y, Ce, Eu, Gd, and Lu, with the content of each element varying greatly depending on the LED technology. In the second part of this research, two new approaches for liberation and concentration of valuable components from LED modules are presented and compared: a chemical route and a thermal route. The chemical treatment leads to a highly selective separation of LED chips and encapsulation. Enrichment factors up to about 125 are achieved, and a concentrate is obtained containing approximately 14 wt% of the aforementioned valuable components. However, the process requires aromatic solvents, which are viewed as toxic. The thermal treatment results in separation of the aluminium heat sink from all other components of the LED module. Enrichment is approximately ten times lower, but the approach is technically feasible.