Organics removal from aqueous phase

Rohm and Flaas Company has developed Amberlite polymeric adsorbent resins that can be used to remove organic compounds from contaminated groundwater, aqueous wastes, and vapor-phase wastes. Amberlite XAD-4 is a crosslinked polystyrene-type polymer. It is hydrophobic and has no ionic functional groups incorporated into its resin structure. The material is most useful in removing low-molecular-weight organic substances from aqueous systems. Amberlite XAD-4 has been commercially available since the 1970s. 

Steam injection and vacuum extraction (SIVE) is a patented, commercially available in situ technology. SIVE has been used to remove non-aqueous-phase liquids (NAPLs), diesel fuel, jet fuel, semivolatile and volatile organic compounds (SVOCs and VOCs), chlorinated solvents, acetone, and benzene, toluene, ethyl benzene, and xylenes (BTEX) from soil and ground-water. 

The product from Step 3 (0.75 mmol) was dissolved in 7.5 ml THE and 7.5 ml water to which was added lithium hydroxide monohydrate (0.83 mmol) and the mixture stirred overnight at ambient temperature. The organic solvent was removed, the aqueous phase acidified with 1 M HCl, and the product extracted twice with 50 ml CH2CI2. The organic phase was dried and evaporated under reduced pressure. The Z-isomer was isolated by lyophilisation from a mixture of methyl alcohol and water in 95% yield. H-NMR data supplied. 

The reduction of salicylic acid to salicylaldehyde is believed to have been practiced commercially in India and the USSR [27]. Two-phase systems may also be used so that the aldehyde is rapidly removed from aqueous solution by extraction into an organic phase [28-30]. It was shown that correct choice of buffer and a two-phase system allows reductions of aromatic acids to aldehydes in acceptable yield (>50%) in addition, the likelihood of such success is greater with the lower pKa value of the acid and lower E1/2 value for reduction of the corresponding methyl ester [30]. 

Gurel et al. [134] drainage using a salicylaldoxime Pb removal from storage battery mine water Amount of organic solvents, external aqueous phase... 

Many methods are available for removal of organic material from aqueous samples by off-line SPE [7]. Hydrophobic organic material is best extracted by solid poly(sty-rene-DVB) polymers or reversed-phase silica extractants. Polyvinylpyrrolidone (PVP) is an appropriate choice for removal of humic acids, lignins and tannins from water samples. 

The focus in Chapters 7 and 8 is on the specific sample preparation approaches available for the extraction of organic compounds from environmental matrices, principally soil and water. Chapter 7 is concerned with the role of Soxhlet, ultrasonic and shake-flask extraction on the removal of organic compounds from solid (soil) matrices. These techniques are contrasted with newer developments in sample preparation for organic compound extraction, namely supercritical fluid extraction, microwave-assisted extraction and pressurized fluid extraction. Chapter 8 is arranged in a similar manner. Initially, details are provided on the use of solvent extraction for organic compounds removal from aqueous samples. This is followed by descriptions of the newer approaches, namely solid-phase extraction and solid-phase microextraction. 

Adsorption from the liquid phase is used to remove organic components from aqueous wastes, colored impurities from sugar solutions and vegetable oils, and water from organic liquids. Adsorption can also be used to recover reaction products that are not easily separated by distillation or crystallization. Some of the same types of solids are used for both vapor-phase and liquid-phase adsorption, though often adsorbents with larger pores are preferred for use with liquids. 

Liquid-Liquid Extraction of an Organic Chemical from Aqueous Solution It is desired to remove some of the acetone from a mixture that contains 60 wt % acetone and 40 Wt % water by extraction with methyl isobutyl ketone (MIK). If 3 kg of MIK are contacted with 1 kg of the acetone-water mixture, what will be the amounts and compositions of the equilibrium phases ... 

To free the aromatic nitro products from the phenolic impurities, two alternative procedures may be compared with the extraction process commonly used industrially at present. In this, the organic product layer after nitration is first washed with water to remove free acids and then washed with dilute sodium hydroxide (usually 1 to 4N, 15% excess). The separated aqueous phase is neutralised by excess mineral acid to liberate the phenols, 60% to 80% of which separate cind may be removed. The aqueous phase is still saturated with phenols cind is an obnoxious effluent. The process also involves the continuous consumption of caustic soda and strong acid, with consequent high operating costs. 

Toei [38] reported on a column packed with the inner fibers of a disposable diaper for babies, which was used as a separator to remove the aqueous phase from a segmented solvent extraction system. Only the organic phase flows into the deteaor. The column phase separator is simpler than other solvent extraction phase separators (cf. Sec. 3.2.3). The number of samples which could be treated before renewal of the disposable column depends on the volume of the aqueous sample injected. 

R4N][Co(CO)4], which migrates to the organic phase and remove R4hT from aqueous phase, where the rhodium complex remains soluble and active. 

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