Removal of phenols from aqueous solutions with solvating extractants
The removal of selected phenols (phenol, 4-methoxyphenol, 4-fluorophenol, 4-nitrophenol, 4-methylphenol, 4-chlorophenol, 2,4-dichlorophenol) from aqueous streams by liquid-liquid extraction is studied. Butylene and propylene carbonate - are used as green extractants. They permit to remove almost 100% of the examined phenols from feed solutions of phenol concentration about 20 g/dm3. Additionally, stripping of phenols from loaded organic phases is carried out with NaOH. The results of extraction parameters for alkylene carbonates (extraction efficency and distribution ratio) are compared with commercial solvating extractant - Cyanex 923.
Methods of regeneration of spent pickling solutions from steel treatment plants
Facing the still growing demand for metals, particularly for zinc, the recovery of metals from secondary sources should be considered. Spent pickling solutions can be the source of valuable products such as hydrochloric acid, zinc or iron salts or even metallic zinc. The selection of an efficient, selective and economical method for the regeneration of such solutions is a key issue for hot dip galvanizing plants, especially in reference to strict environmental protection regulations.
Extraction of Palladium(II) Ions from Chloride Solutions with Phosphonium Ionic Liquid Cyphos®IL101
The extraction of palladium(II) from hydrochloric acid solutions of various concentrations in the presence of different amounts of sodium chloride with phosphonium ionic liquid Cyphos®IL101 in toluene was investigated. The extraction of Pd(II) is very effective. The percentage extraction of Pd(II) from 0.1 mol dm- 3 HCl solution amounts to 97% with Cyphos®IL101. Both the increase in HCl concentration and the presence of NaCl have a negative influence on the extraction. The extent of extraction from 0.1 mol dm-3 HCl solution in the presence of 0.5 mol dm-3 NaCl is about 80% and from 3 mol dm-3 HCl is lower and amounts to 56%. The extraction of Pd(II) from aqueous 0.1 mol dm-3 HCl and from 0.1 mol dm-3 HCl in the presence of 0.5 mol dm-3 NaCl with this phosphonium ionic liquid is rapid and the equilibrium is achieved after 1 - 2 minutes. The extraction of Pd(II) from aqueous 3 mol dm-3 HCl is slower and the equilibrium is achieved after 5 - 6 minutes.
Quaternary phosphonium salts as effective extractants of zinc(II) and iron(III) ions from acidic pickling solutions
Extraction of zinc(II) and iron(III) from hydrochloric acid solutions using quaternary phosphonium salts, Cyphos® IL 101, Cyphos® IL 104, Cyphos® IL109 and Cyphos® IL 111 in mixtures with toluene, was studied. Trihexyl(tetradecyl)phosphonium chloride (Cyphos® IL 101) and trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate (Cyphos® IL 104) showed the best zinc(II) and iron(III) extraction abilities. After three stages of zinc(II) extraction with Cyphos® IL 101 and Cyphos® IL 104 the efficiencies were 100 and 93.6%, respectively. Total iron(III) transport to the organic phase was achieved after two separation stages and amounted to 82.1 and 100% for Cyphos® IL 101 and Cyphos® IL 104, respectively. Zinc(II) and iron(III) could be effectively stripped from the loaded organic phases with 0.5 mol dm-3 sulfuric acid. The more hydrophobic the character of the anion type of phosphonium salts, the lower the efficiency of extraction.
Removal of Zn(II) from chloride acidic solutions with hydrophobic quaternary salts
The equilibrium of zinc(II) extraction from hydrochloric acid solutions with phosphonium and ammonium quaternary salts and their application as carriers in polymer inclusion membranes were studied. The most efficient was the extraction of zinc with the use of chlorides and bromide of ammonium and phosphonium salt (more than 90%). Quaternary ammonium and phosphonium chlorides and bromide are efficient extractants of zinc(II) from hydrochloric acid solutions. Two-fold molar excess of extractant over Zn(II) is necessary for efficient extraction (100%). Solvent extraction power of the extractants studied decreases with increasing hydrophobicity of the anion in the following sequence: QPCl > QPBr > QPBis > QACl > QABF4 > QPBF4 > QPPF6 > QPNtf2. A solution of 1 M H2 SO4 is chosen as the best stripping phase from the technological and economical point of view. Transport across polymeric inclusion membrane enables concentration of the stripping solution; however it takes a very long time.
This paper presents investigation on removal of low molecular organic acids (acetic, lactic, succinic and fumaric) from aqueous solutions with reactive extraction. The results specifically show that the extraction efficiency of acids depends on the type of extractant, diluents of the organic phase and the initial pH of the aqueous phase. It is possible to separate succinic or fumaric from lactic and acetic acids with high selectivity with the use of TOA and Aliquat 336, respectively. Increasing the pH of the aqueous phase results in a reduction of fumaric acid extraction efficiency with solvating extractants. This can be explained by the decreasing share of acidic form, whose extraction is favored by these extractants. Efficient extraction of both fumaric acid and fumarate using Aliquat 336 can be explained by the ionic structure of the quaternary ammonium salt, capable of transporting both forms of the acid.