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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