Heavy metal chloride complex

Based upon the above concept, three different types of membrane separation, i.e., (1) liquid membrane separation which utilizes lipophilic anion-exchangers as mobile carriers, (2) polymeric membrane separation in which the anion-exchange sites function as fixed carriers, and (3) polymeric plasticizer membrane separation in which the membrane is composed of polymeric support, membrane plasticizer, and lipophilic anion-exchangers as a novel membrane material are discussed in relation to their transport efficiency and selectivity for separation of heavy metal chloride complexes. 

Extraction of Heavy Metal Chloride Complexes. The successive formation constants of some heavy metal ions with chloride ion are summarized in Table I (5). Since Pb(II), Cd(II) and Hg(II) are strongly complexed by chloride ion, selective extraction systems for the separation of these heavy metal ions can be designed (9-... 

For back-extraction of the heavy metal chloride complexes from the chloroform phase into 1.0 mM HCl, the efficiency was reversed Pb(II) (99%) > Zn(II) (92%) > Cd(II) (75%). Thus a very high efficiency for back-extraction of Pb(II) was observed. 

Similar to the solvent extraction system mentioned above, a selective sorption of heavy metal chloride complexes has been reported for anion-exchange resins (5, 13). Thus a polymeric membrane having an anion-exchange sites (anion-exchange... 

These results demonstrate that the permeation selectivity and efficiency of heavy metal chloride complexes were controllable by both the extraction step at membrane-source phase interface and the stripping step at membrane-receiving interface. Thus the present membrane separation is quite effective for separation of Pb(II) and Cd(II) from other heavy metal ions in solutions. ... 

Certain heavy metal ions complex with chloride, bromide, and iodide ions to form metal halide complexes in solution, according to the following equation (5) ... 

The theory and application of this fluorescence method have been discussed in detail by LePecq and others (3,8). The assay requires that there is sufficient ionic strength to minimize ionic binding (e.g., O.IM sodium chloride), that the pH is 4-10, that no heavy metals are present, that the fluorescence is not enhanced on binding to other excipients (e.g., proteins) and that at least portions of the nucleic acids are not complexed. These requirements can usually he met when dealing with recombinant products in some cases the samples must he manipulated to create the appropriate conditions. In the intercalative method of dye binding, proteins rarely interfere with the assay, and procedures have been developed to remove the few interferences they may cause (e.g., the use of heparin or enzymatic digestion of the protein 9). 

A complex ion is one that contains more than one ion. Because of its effect on mobility, complexation, the process by which complex ions form in solution, is very important for heavy metals and may be significant for organic wastes. Heavy metals are particularly prone to complexation because their atomic structure (specifically the presence of unfilled d-orbitals) favors the formation of strong bonds with polar molecules, such as water and ammonia (NH3), and anions, such as chloride (CO and cyanide (CN ). Depending on the chemistry of an injected waste and existing conditions, complexation can increase or decrease the waste s mobility. 

Natural inorganic ligands of heavy metals in subsurface water, which are present in a concentration of about 1 millimolar, include nitrite, sulfate, chloride, carbonate, and bicarbonate. These potential ligands generally are efficient only under special conditions. For example, in an alkaline environment, carbonate and bicarbonate can be significant complexors of transition metals like Cu or the uranyl ion, and cadmium may be complexed with Cl" or SO to form... 

The block copolymer of ethylene oxide and 3,3-dimethylthietane shows useful properties of complexing halogen and heavy metal salts (79MI51402). Thietanes can be polymerized with methylmagnesium iodide as well as with a variety of electrophiles such as methyl sulfate, trimethyloxonium tetrafluoroborate, triethylaluminum, boron trifluoride and phosphorus trifluoride (67IC1461, 67MI51400). Thietane (210) has been patented as a stabilizer for poly(vinyl chloride) (73USP3767615). 

There are two treatability groups of dissolved metals for chemical precipitation, complexed and non-complexed metals. Non-complexed metals can be removed by a direct precipitation with such a chemical as lime (Ca(OH) ), caustic (NaOH), sodium sulfide (Na2S), ferrous sulfide (FeS), or sodium carbonate (NajCOj). Complexed metals require coprecipitation with ferrous sulfate (FeS04), ferrous chloride (FeClj), or sodium dimethyl dithiocarbamate (DTC) in addition to a regular precipitant such as caustic or lime. Electrochemically generated ferrous ion is also effective in removing a wide variety of heavy metals, including hexavalent chromium. 

Potassium Vanadicyanide, K3[V(CN)6], is prepared by the addition of excess of concentrated potassium cyanide solution to a concentrated solution of vanadous chloride, VC18 precipitation in the cold with alcohol gives rise to small rhombohedral plates. The solution is not very stable and rapidly becomes turbid, while addition of an acid produces the green colour which is characteristic of the V ion. The complex ion [V(CN)8]" appears, therefore, to be unstable, unlike the corresponding [Fe(CN)e] ", [Cr(CN)J ", and [Co(CN)e] " complex ions. The solution reacts with salts of heavy metals to yield variously coloured precipitates of double cyanides.7... 

The formation of complex compounds with chloride ions in the case of samples polluted by heavy metals can lead to erroneous results (a solution of sodium chloride is added to the sample to obtain the appropriate conditions for bacteria).69... 

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