Calcination process is a method used for gamma rays mass attenuation coefficient enhancement of natural bentonite clay nano-particles. This process eliminates water and organic matter from bentonite clay structure which have low mass attenuation coefficient values. There are two opposite effects on mass attenuation coefficient values; oxides content increases after calcination process which enhances mass attenuation coefficient values and particle size of calcinated bentonite increases which decreases mass attenuation coefficient values. In order to enhance mass attenuation coefficient value for natural bentonite, a physical ball milling must introduced after calcination process that decreases particle size. Calcination process is done at 700 ̊C for two hours because dehydration is completed above 500 ˚C while dehydroxylation observed at 700 ˚C. Mass attenuation coefficients are measured for calcinated and ball milled bentonite clay at different energies (662, 1173 and 1332 keV) and different pressing pressures (50, 100 and 150 bar). Narrow beam transmission technique and two different sources (Cs-137 and Co-60) are used for mass attenuation coefficient measurements, also particle size are measured by two different methods dynamic light scattering and Williamson-Hall size analyses using XRD patterns. All samples are coated by polyvinyl alcohol polymer.
Research Article
Shielding Properties Enhancement of Bentonite Clay Nano Particles Coated by Polyvinyl Alcohol Polymer
https://doi.org/10.21203/rs.3.rs-645961/v1
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Calcination process
bentonite Nanoparticles
PVA polymer
Mass attenuation coefficient
WinXCom
Table 1
Chemical composition analysis for natural and calcinated bentonite clay.
|
Oxides (%) |
SiO2 |
Al2O3 |
P2O5 |
TiO2 |
Fe2O3 |
CaO |
MgO |
Na2O |
K2O |
L.O.I |
Total |
|
Natural Bentonite |
30 |
13.5 |
0.34 |
0.34 |
3.2 |
15.2 |
4.03 |
1.4 |
0.61 |
30.34 |
98.96 |
|
Calcinated Bentonite |
29.6 |
13.7 |
0.54 |
0.45 |
4.2 |
34.2 |
3.8 |
1.9 |
0.81 |
8.67 |
97.87 |
Table 2
Measured gamma photons with and without calcinated bentonite and ball milled bentonite samples [Calcinated, ball milled calcinated (50, 100 and 150 bar)] at different thicknesses and different energies.
|
Energy Thickness |
662 |
1173 |
1332 |
Energy Thickness |
662 |
1173 |
1332 |
||||||
|
|
Calcinated bentonite (50 bar) |
Ball milled bentonite (50 bar) |
|
||||||||||
|
0 |
18206 |
3199 |
2264 |
0 |
|
19304 |
3082 |
2121 |
|
||||
|
0.581 |
17371 |
3102 |
2257 |
0.514 |
|
18380 |
2976 |
2102 |
|
||||
|
1.052 |
16955 |
3028 |
2216 |
0.809 |
|
17915 |
2910 |
2054 |
|
||||
|
1.771 |
16077 |
2874 |
2061 |
0.855 |
|
17908 |
2904 |
2045 |
|
||||
|
1.948 |
15799 |
2828 |
2049 |
1.192 |
17078 |
2800 |
1988 |
|
|||||
|
2.605 |
14892 |
2656 |
1951 |
1.421 |
|
16660 |
2749 |
1939 |
|
||||
|
2.943 |
14290 |
2599 |
1910 |
|
|||||||||
|
|
Calcinated bentonite (100 bar) |
|
Ball milled bentonite (100 bar) |
|
|||||||||
|
0 |
19859 |
3029 |
2158 |
0 |
17978 |
3060 |
1881 |
|
|||||
|
0.508 |
19342 |
3001 |
2123 |
0.525 |
17045 |
2971 |
1870 |
|
|||||
|
1.008 |
18420 |
2924 |
2080 |
0.625 |
17010 |
2954 |
1848 |
|
|||||
|
1.598 |
17784 |
2803 |
1989 |
0.861 |
16613 |
2891 |
1805 |
|
|||||
|
1.754 |
17450 |
2760 |
1962 |
1.513 |
15351 |
2701 |
1703 |
|
|||||
|
2.286 |
16241 |
2615 |
1860 |
1.87 |
14453 |
2610 |
1635 |
|
|||||
|
2.56 |
15490 |
2531 |
1815 |
|
|||||||||
|
|
Calcinated bentonite (150 bar) |
|
Ball milled bentonite (150 bar) |
|
|||||||||
|
0 |
18356 |
3121 |
2309 |
0 |
17344 |
3108 |
2330 |
|
|||||
|
0.419 |
17793 |
3042 |
2262 |
0.525 |
16952 |
3064 |
2321 |
|
|||||
|
0.813 |
17175 |
2936 |
2202 |
0.57 |
16777 |
3043 |
2314 |
|
|||||
|
1.336 |
16177 |
2798 |
2113 |
1.145 |
15744 |
2883 |
2187 |
|
|||||
|
1.811 |
15350 |
2677 |
2035 |
1.487 |
15003 |
2772 |
2101 |
|
|||||
|
2.26 |
14435 |
2575 |
1939 |
1.721 |
14320 |
2671 |
2046 |
|
|||||
|
2.487 |
14158 |
2527 |
1895 |
|
|
|
|||||||
Table 4
Experimental and theoretical mass attenuation coefficient at different energies for calcinated bentonite clay pressed at 100 bar and the corresponding deviation values (%).
|
Energy (keV) |
µm (Experimental) |
µm (Theoretical) |
Deviation (%) |
|
662 |
0.0732 |
0.0774 |
5.4 |
|
1173 |
0.0584 |
0.059 |
1.01 |
|
1332 |
0.0549 |
0.055 |
0.18 |
Table 5
Comparison between mass attenuation coefficients of ball milled calcinated bentonite and other shielding materials.
|
Shielding material |
Energy (keV) |
Reference |
||
|
662 |
1173 |
1332 |
||
|
Ball milled calcinated bentonite |
0.0836 |
0.069 |
0.066 |
Present work |
|
Natural bentonite |
0.076 |
0.059 |
0.056 |
[44] |
|
Ordinary concrete |
0.078 |
0.059 |
0.055 |
[48] |
|
Cement |
0.071 |
0.05 |
0.047 |
[49] |
|
Sand |
0.077 |
0.058 |
0.054 |
|
|
Gypsum |
0.058 |
0.041 |
0.039 |
|
|
High-density polyethylene |
0.079 |
0.06 |
- |
[50] |
|
Zirconium |
0.095 |
0.057 |
- |
[51] |
|
Acrylic |
0.101 |
0.11 |
- |
|
|
Composite (Ba, Al, Si) |
0.117 |
0.084 |
- |
|
|
Aluminum |
0.074 |
- |
- |
[52] |
|
Bulk zinc oxide |
0.0739 |
0.054 |
- |
[53] |
|
White marble |
0.078 |
0.058 |
0.053 |
[54] |
|
Pink marble |
0.078 |
0.058 |
0.053 |
|
No competing interests reported.