Table 2 Pretreatment conditions, efficiency, and results of different alcohol organosolv pretreatment systems

Ethanol

Softwood

63 wt%

–

~ 235

90

Formic acid

~ 65% delignification

(Agnihotri et al. 2015)

Sugarcane bagasse

50 wt%

–

~ 210

90–120

~ 80% delignification

Hybrid poplar

60%

8:1 ratio

160–180

60

H₂SO₄

> 75% Glucose hydrolysis yields

(Bär et al. 2018)

Wheat straw

60%, w/w

–

200

60

–

Organosolv lignin

(De Wild et al. 2012)

Silver birch

50% or 60%

1:10

180 or 200

15 or 30

H₂SO₄

Cellulose content increased from 37.1 to 69.2%, with 12.96% hemicellulose, and 13.24% lignin content

(Monção et al. 2021)

Isobutanol

Beechwood

50% v/v aqueous isobutanol

1:10

160

120

Mild acid-free oxidative conditions

High delignification (97%), oligosaccharide recovery in 43.3% aqueous fraction, 92.6 wt% cellulose-rich pulp

(Karnaouri et al. 2021)

1-Butanol

Sorghum bagasse

25%

6:80

200

60

H₂SO₄

84.9% and 15.3% highest cellulose and low lignin content, respectively

(Teramura et al. 2018)

Methanol

Cauliflower stalk

100%

–

121

30

Sodium acetate

77.85 ± 0.58% cellulose yield and 1.07 ± 0.71% hemicellulose yield

(Majumdar et al. 2019)

Cauliflower leaf

100%

–

121

30

Sodium acetate

74.97 ± 0.39% cellulose yield, 6.84 ± 0.81% hemicellulose yield

Hazelnut skin

50% v/v

–

130, 160, 200

60

H₂SO₄

Lignin content reduction from 39.66 to 34.73%, increase in bioavailable sugars

(Oliva et al. 2021)

Glycerol

Eucalyptus wood

56% aqueous glycerol

1:10

200

69

–

65% lignin solubilisation, 99% cellulose retention in biomass

(Romaní et al. 2016)

Wheat straw

70% aqueous glycerol

1:20

220

180

–

95% cellulose retention, 65% lignin removal, 70% hemicellulose removal

(Sun et al. 2015)

Sugarcane bagasse

70% industrial glycerol

1:20

200–240

60–300

–

> 65% lignin and > 80% hemicellulose removal, > 95% cellulose retention

(Sun et al. 2016)

THFA

Hybrid Pennisetum

–

1:12

100

120

H₂SO₄

87.5% enzyme digestibility, recovered

80.8% total glucan in the untreated HP

(Tan et al. 2019)

Ethylene glycol

Degraded empty fruit bunch

50% v/v ethylene glycol

1:10

80

45

NaOH

75.1% High delignification, 81.5% hemicellulose removal, and 90.4% cellulose recovery

(Chin et al. 2020a)

Bagasse

–

1:10

110–150

60

HCl

~ 99.3% hemicellulose and ~ 67.1% lignin removal, 94.3%, glucose recovery yield

(Wei et al. 2021)

–

1:10

110–150

60

NaOH

 ~ 90.9% lignin removal and ~ 28.8% hemicellulose degradation, 92.5% glucose recovery yield

Rice straw

90% ethylene glycol

1:20

150

30

AlCl₃

88% delignification, 90% hemicellulose removal, 100% cellulose recovery

(Tang et al. 2019)