摘要:

The 1% breakthrough volumes (BTV) for TcO4^on Reillex™-HPQ anion exchange resin columns have been measured as a function of flow rate. The 1% BTV is defined as that point in the column loading when an aliquot of eluent contains 1% of the activity of an equivalent aliquot of column feed solution. The 2.54 × 50 cm

ISSN:0736-6299    

DOI:10.1080/07366299908934664

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Cadmium sorption from aqueous solutions on sulfonic (C-150) and iminodiacetic (S-930) Purolite macroporous resins was investigated. The influence of operating variables such as initial pH, Cd(H) concentration, time and temperature on the equilibrium parameters was measured. The ion preference and sorption ability of resins, i.e. binding constant (b) and saturation capacity {xm), derived from sorption isotherm, depend on the functional group structure. The Cd(II) uptake is only particle diffusion controlled. The kinetic parameters, i.e. t1/2values for 50 % attainment of equilibrium sorption, rate constant (K¯ ) and diffusion coefficient (D¯) are higher on the sulfonic resin. The “moving boundary” particle diffusion model fits the entire ion sorption process on chelating resin, but only the initial sorption on the sulfonic resin, confirming the difference in chemistry between chelation and ion exchange.

ISSN:0736-6299    

DOI:10.1080/07366299908934665

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This paper presents the results of the selective removal of Zn(II) from Cu(II), Cd(II), Ni(II) and Pb(II) using ‘Extraction Chromatographic Resins’ Lewatit TP80T84, which contains dK2,4,4-trimethylpentyl)pbosphinic acid as active component. The extraction and selectivity patterns of the resin were obtained from the metal distribution coefficients as a fiinction of pH. Experimental data of Pb(II), Ni(II) and other natural water occurring metal ions, such as Ca(II), were analyzed graphically and numerically in order to describe the metal extraction reactions. Analysis of the results showed that the extraction of these metal ions can be explained assuming the formation of metal complexes in the resin phase with a general composition ML2(q3HL)q, where q takes different values depending on the metal studied. Finally the efficiency of the resin in the selective removal of Zn(II) from the toxic heavy metal group Cu(T±), Cd(II), Ni(II) and Pb(II) were evaluated.of divalent metal ions (Zn(II), Cu(II), Cd(n), Ni(II), Pb(n)). Concerning the extraction selectivity of Lewatit TP80784 resins versus Zn(II), Cu(II)( Cd(n), Ca(n), Pb(n) and Ni(II), no differences have been found in comparison with the selectivity of this extractant in organic solvents (36). The results of the numerical treatment indicate that the extraction of Pb(n) and Ni(II) can be explained by assuming the formation of PbL2(HL2and NiL2(HL)2. However, the extraction of Ca(II) can be explained assuming the formation of two species CaL2and Ca(NO3)L|The analysis of the separation factors indicates that Lewatit TP80784 allows a quantitative separation of Zn(II) from Cd(II), Ni(II) and Pb(II) with ApHso greater that 2 and quasi-quantitative separations (90-95%) from Cu(II)|The results obtained in the extraction of Zn(IT), Cu(H), Cd(II), Ni(II), and Pb(n) from water samples in column experiments are very satisfactory, and the sytem will be used on-line in a multicomponent spectrophotometric method for the monitoring of low levels of toxic metal ions in surface waters.

ISSN:0736-6299    

DOI:10.1080/07366299908934666

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A new technology for removal and recovery of coagulants from water clarifier sludge has been optimized at laboratory scale pilot plant level. The process is based on the use fibrous exchangers showing good kinetic and thermodynamic performance toward coagulant species (Al, Fe) present in the acidic leachate (pH 3.5) from water clarifier sludge. The innovation allows for the solution of the environmental problem related to clarifier sludge disposal (residual solids after metals leaching are safely applied to land), and quantitative recovery of coagulants to the water potabilisation operations

ISSN:0736-6299    

DOI:10.1080/07366299908934667

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The precipitation behaviour of the compounds in the system, divalent metal-hexacyanoferrate(II)-sodium silicate, has been investigated. Under suitable conditions, copper, cobalt and nickel-based composite sorbents have been prepared. These sorbents were very effective in removing cesium from neutral solutions. In regard to exchange capacities, copper hexacyanoferrate (Cu-Hcf) composites exhibited highest values and these values were found to be independent of silica content. Similarly, rates of cesium uptake also were higher and these rates were not affected by granulation of copper-based materials. There was little decrease in the rates in hydrazine containing nitric acid solutions. Several cycles of batchwise sorption and desorption operations were performed with Cu-Hcf composites and quantitative recovery of cesium from loaded sorbents was achieved using nitric acid

ISSN:0736-6299    

DOI:10.1080/07366299908934668

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor