Recovery of Palladium(II) and Platinum(IV) in Novel Extraction Systems

Recovery of platinum group metals (PGM) from complex aqueous solutions generated as a result of leaching of various spent materials (e.g., spent automotive converters) is a vital issue in the context of the circular economy. In this study pyridinium derivatives containing an imidoamide or imine moiety (i.e., 3-[1-(2-ethylhexyloxyimine)methane]-1-propylpyridinium chloride, 3-[1-(decyloxyimine)methane]-1-propylpyridinium chloride, 3-[1-(decyloxyimine)ethane]-1-propylpyridinium chloride and 4-[1-amine(2-ethylhexyloxyimine)]-1-propylpyridinium chloride) are proposed as novel extractants for recovery of palladium(II) and platinum(IV) from model chloride aqueous solutions. The results of liquid-liquid extraction from one-component solutions of palladium(II) or platinum(IV) showed that quaternary pyridinium salts can be used as effective extractants for platinum metal ions. Moreover, PGM extraction from a two-component mixture proved no evident selectivity in the transfer of one of the metal ions to the organic phase. As the best extractant among the investigated ones, D3EI-PrCl (with straight alkyl chain at substituent) can be pointed out, however, problems with effective stripping or phase disengagement after stripping should be indicated as a drawback of the organic phases used. Further investigation should focus on the improvement of the organic phase properties (e.g., increase in hydrophobicity of the extractants and addition of an organic phase modifier) towards stripping efficiency.

Classification Of Isoxynoline Alkaloides By Structure And Effect

The chemistry of pyridine and its partially or completely hydrogenated analogues, used in various fields, is one of the fastest growing fields of interest for chemists and pharmacologists. Pyridine, pyridine, and tetrahydroisoquinoline rings are the major fragments of many natural and synthetic biologically active substances. Quaternary pyridinium salts are widely used as alkylating agents, interfacial migration catalysts, antiseptics, ionic liquids as surfactants and anticorrosives.

Preparation of quaternary pyridinium salts as possible proton conductors

On basis of earlier experimental experience, the transfer of protons in salts of the organic cation-inorganic anion type occurs primarily through directional arrangement of the anion-anion type short hydrogen bonds. The submitted work presents the preparation of quaternary pyridinium salts of inorganic hydrogen anions in the absence of solvent molecules in their crystal structure. These substances can form only the above-described anion-anion type hydrogen bonds; in addition, the absence of solvate anions increases the stability of the prepared compounds. A total of six substituted pyridinium salts were prepared, four of which have not been described yet: 1,2,4,6-tetraphenylpyridinium perchlorate, 1-benzyl-2,4,6-trimethylpyridinium perchlorate, 1,4-dimethylpyridinium hydrogen sulphate, 1,4-dimethylpyridinium dihydrogen phosphate, 1,4-dimethylpyridinium hydrogen sulphate, and 1,2-dimethyl-5-ethylpyridinium dihydrogen phosphate. Three of these substances were characterised by X-ray structural analysis: 1,2,4,6- tetraphenylpyridinium perchlorate crystallises in the orthorhombic system, space group Pbca; 1- benzyl-2,4,6-trimethylpyridinium perchlorate crystallises in the monoclinic system, space group P2