Uptake, of metal ions

Horwitz EP, Chiarizia R, Dietz ML, Diamond H, Nelson DM (1993a) Separation and preconcentration of actinides from acidic media by extraction chromatography. Anal Chim Acta 281 361-372 Horwitz EP, Chiarizia, R., Diamond H, Gatrone RC, Alexandratos SD, Trochimzuk AQ, Crick DW (1993b) Uptake of metal ions by a new chelating ion exchange resin. 1. Acid dependencies of actinide ions. Solvent Extr Ion Exch 11 943-966... 

Savvaidis I, Hughes M, Poole R (1992) Differential pulse polarography a method of directly measuring uptake of metal ions by live bacteria without separation of biomass and medium. FEMS Microbiol Lett 92 181-186 Savvaidis I, Hughes MN, Poole RK (2003) Copper biosorption by Pseudomonas cepacia and other strains. World J Microbiol Biotechnol 19 117-121 Scott JA, Palmer SJ (1988) Cadmium biosorption by bacterial exopolysaccharide. Biotechnol Lett 10 21-24... 

Grigal, D.F. 2003. Mercury sequestration in forests and peatlands A review. Journal of Environmental Quality, 100, 393-405. Gjengedal, E. Steinnes, E. 1990. Uptake of metal-ions in moss from artificial precipitation. Environmental Monitoring and Assessment, 14, 77-87. 

An ion exchanger (0.04 g) and a metal ion solution (10 4 M, 25 ml) were taken into 50 ml Erlenmeyer flasks. Then, the flasks were shaken with a mechanical shaker at 30 °C for 24 h. The metal ion concentration in the aqueous phase was determined by means of ICP-AES. From a decrease of the metal ion concentration in the aqueous phase, uptake of metal ion in mmol/g was calculated. Here, only nitric acid was used in the pH adjustment. 

Mohapatra, P.K. Sriram, S. Manchanda, V.K. Badheka, L.P. Uptake of metal ions by extraction chromatography using dimethyl dibutyl tetradecyl-l,3-malonamide (DMDBTDMA) as the stationary phase, Sep. Sci. Technol. 35 (1999) 39-55. 

INFLUENCE OF HUMIC SUBSTANCES ON THE UPTAKE OF METAL IONS BY NATURALLY OCCURING MATERIALS James H. Ephraim and Bert Allard... 

Recent studies have shown that the adsorption capacity of a common organic component (humic acid) can exceed that of clay minerals. A change in pH can cause marked changes in the uptake of metal ions by such humic acids [255] or humic acid-clay mixtures [256]. hi this connection, Slavek et al. [257] examined the effect of various electrolytes on the organic acid-metal ion equilibria, with a view to clarifying the situation. 

Further, compartmentalization allows cells to control the import of nutrients and the export of products that manipulate the environment, or excrete waste. These include siderophores that enhance uptake of metal ions, quorum-sensing molecules that inform cells of the presence of others of their kind, molecules that form biofilms that allow attachment to surfaces and protection from mechanical and chemical stress, and toxins that inhibit the growth of competitors. 

Subsequent work has shown problems with the chelating resin technique. These are (a) Use of the resin in the H+ form involves a decrease in the pH of the effluent because of the release of hydrogen ions, thus causing a deterioration in the efficiency of the uptake of metal ions on to the resin. The maximum efficiency is observed when the resin is converted to forms other than H+ (e.g., Na+, NH4+, K+, Mg2+, Ca2+) [11]. (b) A significant fraction of Cu, Pb, Cd and Zn in seawater exists in a form which is not retained by the chelating resin Chelex-100 [12], even after acid digestion [11]. Figura and McDuffie [13] have likewise obtained incomplete recoveries for the uptake of Cd, Co, Cu, Ni and Zn from river water by columns of Ca-chelex. 

Table 3.4 Bjerrum s a parameter as calculated from c and x and corresponding properties of the proton. The ligands most often given away by both green plant roots and fungal mycelia produce a 0, making uptake of metal ions less sensitive towards pH changes even though certain of these ligands are fairly readily protonated, i.e. are considerable Brdnsted bases. This does not hold for those amino acids which are employed by grasses, mosses mainly, pointing to decreased selectivity...

The fact that the selective uptake of metal ion by the ion exchanger is associated with highly coordinated species undetectable in the solution, even vtiien ligand concentrations in the two phases have been kept similar, has to be attributed to either the immobilization of these species by their interaction with the organic component of the exchanger matrix or to sizable reduction of activity coefficients of ion species in the resin phase because of the lowering of the dielectric constant of the resin phase media. 

The uptake of ions may be complicated by changes in the conformation of the protein such as may occur during swelling or supercontraction. For example, Hojo and Sugawara (1958) report a 60 % increase in uptake of Cu++ from CUSO4 solution when wool fibers are stretched by 50 %. The uptake of metal ions is accompanied by the release of hydrogen ions (Hojo and Hojo, 1958) from the fiber. The presence of natural pigment in animal... 

Sanders et al. (1983) have also shown that the effects of Cu(II) on the growth of crab larvae and on their metallothionein with copper chelate buffer systems must be interpreted on the basis of free Cu ion activity. The data obtained reveal predictable relations between [Cu ] in seawater and processes at the cellular and organismic levels. Similarly, the uptake of metal ions by plants (e.g., of aluminum) is usually related to free metal-ion activity. Others have shown that the chelation of a variety of metals reduces the toxicity of metals to organisms for example, a reduction in the uptake of mercury by fish in the presence of EDTA and cysteine a reduction in copper and/or zinc toxicity to... 

This principle becomes important when thinking about the factors that limit uptake of metal ions by plant roots or leaching of these ions through soils. 

Basic Enhances uptake of organics May, in some cases, decrease the uptake of metal ions... 

EPSs may also contribute to the provision of reduced oxygen tension and participate in the uptake of metal ions. Acidithiobacillusferrooxidans is one of the most commonly used microorganisms in bioleaching. Once cells have attached to the mineral, an EPS layer is developed over the next few days, creating the contact between bacterial cells and the sulfidic energy source. 

Waterhyacinth plants [Eichhornia crassipes (Mart.) Solms], which infest waterways in many parts of the world, were used as a model system for studying uptake of metal ions by floating acpiatic plants. Observed rates of uptake of manganese(II)-54 and iron(III)-59 by water hyacinth compare favorably with the values expected based upon a coordination model control by chelation with dihydrogen ethylenediamine- tetraacetate ion and control by metal(II) carbonate solubility. Agreement depends upon the assumption of the reduction of iron(III) species by the plant. 

Siibsecpiently, biocontrol proved to be successful in controlling waterhyacinth plants (12), particularly when undertaken in conjunction with chemical control, though not all types of waterhyacinth plants responded similarly(c/. 13). Appreciating the differences in the uptake of metal ions by the plant types was a key to understanding their characteristics, especially size and insect avoidance. 

If electrolyte ligand - metal ion complex is weak than polymer metal ion chelates, the more metal ion can form complex with polymer hence uptake of metal ion is more. But if this complex is strong than polymer - metal ion chelates, more metal ions form strong complex with electrolyte hgand which make metal uptake capacity lower by polymer. 

Experimentally, to ascertain the role, if any, of surface oxygen complexes in the uptake of metallic ions, a correlation is looked for between amounts of ions adsorbed (N/ ) and the... 

---