scholarly journals The Adsorption of Phosphate on Mica Surfaces

2021 ◽  
Author(s):  
◽  
Raymond Alan Hoare

<p>The surface chemistry of the 001 face of cleaved mica sheets was studied with a view to understanding some of the fundamental processes underlying the phenomenon of fixation of phosphate by soils. Radiochemical techniques were developed to make quantitative studies of the adsorption, an important part of these being practical procedures for obtaining sufficient cleanliness and freedeom from airborne contamination. Lack of uniformity of adsorption, as shown by autoradiography, was taken to indicate contamination, and techniques were developed to avid this. Other techniques enabled the continuous monitoring of the sample during adsorption or desorption kinetic experiments. It was shown that adsorption of phosphate on the untreated mica sheets was low, but the adsorption was greatly enhanced if the mica had been treated with aqueous solutions of certain cations such as gallium, aluminium and iron. Form the measurement of the amount of phosphate adsorbed, as a function of the conditions of aluminium treatment, it was concluded that the phosphate could be absorbed by at least three different processes, all of which could be of importance in phosphate fixation by soils. As well as these processes, which occurred on clean, flat, mica surfaces, there were others, involving the edges of mica and sheets, and unknown, but probably organic, films on both mica and air-water surfaces. These could all be of comparable importance in soils. The kinetic measurements of phosphate adsorption and desorption on aluminium-treated mica indicated that many hours were required for attainment of equilibrium, and were quantitatively consistent with the hypothesis that in some cases the adsorption and desorption kinetics were controlled by diffusion of phosphate into particles of some material, possibly a hydrous oxide, adsorbed on the mica. The existence of such particles was supported by the fact that up to one phosphate molecule per two square Angstrom units of mica surface was adsorbed, (and this did not appear to be a value at which the surface was saturated.) Kinetic measurements of 67 Ga sorption processes were consistent with diffusion of gallium through a thin water film, with a diffusion coefficient several orders of magnitude lower than that of single ions in free solution. This may indicate that the gallium was adsorbing as particles, in agreement with the requirements of the phosphate experiments.</p>

2021 ◽  
Author(s):  
◽  
Raymond Alan Hoare

<p>The surface chemistry of the 001 face of cleaved mica sheets was studied with a view to understanding some of the fundamental processes underlying the phenomenon of fixation of phosphate by soils. Radiochemical techniques were developed to make quantitative studies of the adsorption, an important part of these being practical procedures for obtaining sufficient cleanliness and freedeom from airborne contamination. Lack of uniformity of adsorption, as shown by autoradiography, was taken to indicate contamination, and techniques were developed to avid this. Other techniques enabled the continuous monitoring of the sample during adsorption or desorption kinetic experiments. It was shown that adsorption of phosphate on the untreated mica sheets was low, but the adsorption was greatly enhanced if the mica had been treated with aqueous solutions of certain cations such as gallium, aluminium and iron. Form the measurement of the amount of phosphate adsorbed, as a function of the conditions of aluminium treatment, it was concluded that the phosphate could be absorbed by at least three different processes, all of which could be of importance in phosphate fixation by soils. As well as these processes, which occurred on clean, flat, mica surfaces, there were others, involving the edges of mica and sheets, and unknown, but probably organic, films on both mica and air-water surfaces. These could all be of comparable importance in soils. The kinetic measurements of phosphate adsorption and desorption on aluminium-treated mica indicated that many hours were required for attainment of equilibrium, and were quantitatively consistent with the hypothesis that in some cases the adsorption and desorption kinetics were controlled by diffusion of phosphate into particles of some material, possibly a hydrous oxide, adsorbed on the mica. The existence of such particles was supported by the fact that up to one phosphate molecule per two square Angstrom units of mica surface was adsorbed, (and this did not appear to be a value at which the surface was saturated.) Kinetic measurements of 67 Ga sorption processes were consistent with diffusion of gallium through a thin water film, with a diffusion coefficient several orders of magnitude lower than that of single ions in free solution. This may indicate that the gallium was adsorbing as particles, in agreement with the requirements of the phosphate experiments.</p>


1996 ◽  
Vol 180 (1) ◽  
pp. 276-284 ◽  
Author(s):  
A. Feng ◽  
B.J. McCoy ◽  
Z.A. Munir ◽  
D.E. Cagliostro

2000 ◽  
Vol 61 (7) ◽  
pp. 4890-4893 ◽  
Author(s):  
L. X. Zheng ◽  
M. H. Xie ◽  
S. Y. Tong

1993 ◽  
Vol 7 (4) ◽  
pp. 207-212 ◽  
Author(s):  
S. Scholl ◽  
H. Kajszika ◽  
A. Mersmann

2008 ◽  
Vol 344 (1-2) ◽  
pp. 183-190 ◽  
Author(s):  
R.I. Slioor ◽  
J.M. Kanervo ◽  
T.J. Keskitalo ◽  
A.O.I. Krause

2012 ◽  
Vol 209-211 ◽  
pp. 1999-2004
Author(s):  
Chang Kun Liu ◽  
Xu Xin Zhao ◽  
Hong Zhu ◽  
Xiao Fang Yue

Adsorption and desorption kinetics is critical in the efficiency and performance evaluation of the adsorbents. In this study, the adsorption and desorption kinetics of copper and/or zinc ions was investigated with the polyamine-functionalized adsorbents (P-TETA). The adsorption kinetics was studied in both single species system (when only one metal ion was present) and binary species system (when both metal ions were present). The adsorption kinetics in single species system was well fitted with two models at two stages for both Cu and Zn ions, indicating that the adsorption was diffusion-controlled at the initial stage and attachment-controlled at later stage. The adsorption kinetics in binary species system revealed the stronger coordination affinity of Cu ion with P-TETA than Zn ion. The desorption kinetics was well fitted with Elovich model for Cu ion desorption only, in both single and binary species system, with a higher desorption rate in single species system.


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