Ion recovery

Ion Flotation and Foam Separation. Ions and dissolved surfactant molecules can be removed from solutions by the agency of foam. In this case ions are sandwiched in foam films. The scientific basis of these processes is weU understood and successes of metal ion recovery from solutions including U, Pt, Au, as weU as different surfactants (detergents) have been reported in the Hterature. 

Hung et al. (1982) developed a sensitive and selective method for silver analysis by reacting silver (I) with 2(3,5-dibromo-2-pyridylazo)-5-diethyl amino phenol in the presence of an anionic surfactant, sodium lauryl sulfate. The ternary complex formed is red and exhibits an absorption peak at 570 nm. Hung and his co-workers employed EDTA as a chelating agent, thereby reducing the interference of common ions. Recoveries were good, and a detection limit of 0.39 ppm of silver was achieved. 

In summary, examination of metal ion recoveries from humic acid samples by different chemical extractants has confirmed that in any extraction procedure very careful consideration must be given to the associated chemical equilibria and the impact of competing reactions. 

Surfactant System IFT oil/surf (d/cm) W, T. % recovery by micellar solubilizat ion % recovery as free phase % recovery as MPM % recovery total Pore vols. of flush... 

Bond Elut (Agilent) and CBA ISOLUTE (International Sorbent technology) both representing an irregular end-capped mixed-mode phase of a weak cation exchanger (carboxylic acid) and a mid-polarity sorbent. /V-butyl-scopolamine was extracted accordingly from equine urine [78], Elution of analytes was achieved by the use of a methanolic solution acidified either with 1 M HC1 [54] or 1 % formic acid [78] allowing competition between QTA and hydronium ions. Recoveries were between 96 and 103 % [54] (Table 4). 

Reverse osmosis also serves some of the waste management and resource recovery needs in the metals and metal finishing industry. Effluent streams from mining and plating operations containing heavy metals, acids, and other chemicals can be treated with reverse osmosis to recover both the metal as its salt, and purified water for reuse. For metal ion recovery from dilute solutions, however, reverse osmosis faces competition from conventional solvent extraction, membrane-based solvent extraction, and its variant, coupled transport (see Section V.F.3). 

Metal ion recovery by cementation 21. Green chemistry The recovery and reuse of... 

Most of the element recovery technology has been involved with separating cation mixtures (see, e.g., [93-96]) but separation of anion mixture is also a potential path to this objective, as the following example shows. Consider the case where a solution containing a certain ion to be removed, e.g., in Bi ion recovery from seawater is exposed to a Br" ion-selective exchanger initially in the Cl" form at temperature Tj. The exchange reaction presented below then results in enrichment of Bi" in the... 

Summary of the Extractants Being Used for Actinide Ions Recovery/Separation by LM-Based Separation Methods... 

In the current research, a major focus was on alum recovery. A stody can be carried out for ferric ion recovery and detailed modeling can be carried out for Fe(III) recovery from ferric chloride-based WTR. 

The amount Vr-Vea is then the volume of dilution water. This should be kept to a minimum to avoid unnecessary energy consumption in the ultimate evaporation step. The ammonium ion recovery efficiency has been defined as... 

Prdtsch, M. Marr, R. "Development of a Continuous Process for Metal Ion Recovery By Liquid Membrane Permeation Proceedings Inter. Solvent Extrac. Conf. 1983, pp 66-67. 

These chelating resins have found most of their use in metal ion recovery processes in the chemical and waste recovery industries. They may find use in fermentation applications where the cultured organism requires the use of metal ion cofactors. Specific ion exchange resins have also been used in laboratory applications that may find eventual use in biotechnology product recovery applications. 

Ion exchange resin materials are based on styrene-divinylbenzene polymers and polyacrylates (Table 4.3). The synthesis of these materials is easily controlled and gives materials of the necessary chemical and physical stability, in terms of uniformity of particle size and shape, porosity and chemical composition. These resins find wide application in demineralisation, water treatment and ion recovery from wastes. 

The next step towards successful development of the SF extraction process is to move from small-scale investigations to bench scale feasibility studies. Bench-scale data will provide information to evaluate process design issues and to establish the utility of this technology. Key conqwnents of this technology that must be evaluated are (a) ligand solubility in SC COj. (b) metal ion extraction into SC CO2, (c) metal chelate solubility in SC CO2, and (d) metal ion recovery from a metal-laden SC CO2 phase. Hie overall goal of the SFE process is the concentration of the contaminants, as depicted in Hgure 6. 

This overview chapter has the objective of introducing the SyiQ>oslum Series volume and the subject of liquid membrane technology. If membranes are viewed as semi-permeable phase separators, then the traditional concept of membranes as polymer films can be extended to Include liquids and liquid-swollen polymers. The addition of a mobile complexatlon agent to the membrane Is known as facilitated liquid membrane separation. Often, In liquid phase facilitated transport systems, the solute flux Is coupled to the opposite flux of another species. This process, common in metal ion recovery schemes, is known as coupled transport. 

Commercial eind laboratory applications of liquid membrane technology are discussed including gas transport, sensor development, metal ion recovery, waste treatment, biotechnology and biomedical engineering. Immobilized liquid membranes, emulsion or liquid surfactant membranes, and membrane reactors are discussed. Economic data from the literature for liquid membrane processes are presented and compared with existing processes such as solvent extraction and cryogenic distillation of air. 

Maureira, A., Rivas, B.L., Metal ions recovery with alginic acid coupled to ultrafiltration membrane, Eur. Polym. J. 45, 573, 2009. 

Hydrogels show a marvelous prospect for the procedure of metal-ions recovery from dilute solutions (Peter 1995, Varma et al. 2004). Recently, the adsorption of natural organic pollutants (such as humic acids) from aqueous solution using chitosan adsorbents has attracted intensive attention in environment and health fields (Ngah and Musa 1998, Wu et al. 2002, Yan and Bai 2005). Adsorbents, derived from a nature polymer, are required for environment-conscious technologies. The adsorptions of metal ions and humic acid from aqueous solutions onto radiation cross-linked chitosan derivatives were introduced here. 

Vieira, R. and Beppu, M. 2005. Mercury ion recovery using natural and crossUnked chitosan membranes. Adsorption 11 731-736. 

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