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Table 2 Particle size, surface area, and crystallinity of milled and unmilled switchgrass samples

From: Gaseous ammonia pretreatment lowers the required energy input for fine milling-enhanced enzymatic saccharification of switchgrass

Sample Particle size (d 50, µm) Surface area (m2/g) CrI (%) Coherent domain size (nm)
KM UT-2 no pretreatment 600 1.34473 62.9 3.1
Plus ball milling 1 day 42.4 2.42792 62.7 3.4
Ball milling 2 days 36.9 3.56033 56.3 3.1
Ball milling 3 days 23.9 4.54339 48.2 2.7
Ball milling 4 days 16.7 4.52749 32.3 2.3
Ball milling 6 days 13.57 3.51319   1.4
Ball milling 10 days 13.2 2.94745   1.3
KM UT-4b no pretreatment 600 ND 61.1 ± 1.9 3.23 ± 0.15
KM UT-4b treated with gaseous NH3, 150–160 °C, 1 h 600 ND 71.0 ± 3.9 3.95 ± 0.07
Plus 5 min in Union Process SD-1 attritor mill 30.2 ND 59.5 3.5
Attritor milling for 10 min 19.0 ND 55.4 3.1
Attritor milling for 15 min 17.8 ND 50.4 3.0
Attritor milling for 20 min 13.55 ND 32.0 2.7
Attritor milling for 30 min 16.4 ND 21.6 2.2
Attritor milling for 60 min 18.9 ND 2.2 1.7
NH3-treated KM UT-4b plus 2 passages through Kemutec 5H Universal Pin Mill 84 ND 73.6 3.9
NH3-treated KM UT-4b plus jet milling in Fluid Energy Model 4 Microjet 23.4 ND 70.0 3.8
NH3-treated KM UT-4b plus passage through Hosokowa 2ACM Air-classifier mill 22.03 ND 66.7 3.5
  1. Particle size, surface area, crystallinity index (CrI) and coherent domain size of 1-mm knife-milled (KM) switchgrass subjected to further fine milling with and without 150–160 °C, 1 h, 10 wt% ammonia pretreatment. The variation is the standard deviation of two measurements