Evaluating the Effect of Hydrofluoric Acid Etching on Quartz Grains using Microscope Image Analysis, Laser Diffraction and Weight Loss Particle Size Estimate Publié en ligne: 10 mai 2022 Pages: 1 - 8 Reçu: 13 mai 2021 Accepté: 24 janv. 2022 © 2022 Grzegorz Poręba et al., published by Sciendo This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.
Fig. 1 Location of the sampling site (A) and material collection from an active sand pit (B). Fig. 2 Random grains before (A) and after 40% HF etching for 60 min (B) and 180 min (C). Note smaller grains ranging from ca. 5 μm up to 100 μm detected after etching (B and C), marked with an arrow. Fig. 3 Random grains before (A) and after 40% HF etching for 60 min (B) and 180 min (C). Note smaller grains ranging from ca. 5 μm up to 100 μm detected after etching (B and C), marked with an arrow. The microscope IA algorithm marks different grains with different colours and draws rectangles for visual validation. Fig. 4 Laser volumetric grain size distributions (A) and grain size distributions (B). Microscope IA with volumetric grain size distributions (C) and grain size distributions (D). IA, Image analysis. Fig. 5 Roundness distribution of quartz grains etched with 40% HF acid for microscope IA. Roundness is defined as 4πA/P2, where A is the area and P is the perimeter. IA, Image analysis.. Fig. 6 Roundness and equivalent diameter of quartz grains etched with 40% HF acid for microscope IA. Roundness is defined as 4πA/P2, where A is the area and P is the perimeter. IA, Image analysis. Fig. 7 Mass etching depth (δrm) vs. etching time (t) assessed from mass loss calculations. LD 1/2ΔDV, LD, 50 and microscope IA 1/2ΔDV, LD, 50 equivalent radius changes. Light blue and red areas correspond to LD 1/2ΔDV, LD, 10 – 1/2ΔDV, LD, 90 and microscope IA 1/2ΔD, IA, 10 – 1/2ΔDV, IA, 90 ranges. LD, Laser diffraction. Initial and final mass loss of etched quartz grains and estimated etched depth of the grains.
Time (min)
Batch A
Batch B
Mean etching depth (μm)
Initial mass (g)
Final mass (g)
Initial mass (g)
Final mass (g)
0*
3.5739
3.5661
3.5033
3.4977
0 ± N/A
30
3.5513
2.9595
3.5981
3.0251
5.1 ± 0.3
45
3.5161
2.7271
3.5524
2.7978
7.0 ± 0.4
60
3.5400
2.5144
3.5099
2.5116
9.5 ± 0.5
90
3.6021
2.2142
3.4692
2.0754
13.8 ± 0.8
120
3.5805
1.8717
3.4540
1.7820
17.6 ± 1.0
150
3.5299
1.5243
3.4676
1.5269
21.7 ± 1.2
180
3.4273
1.2808
3.5608
1.2963
25.2 ± 1.4