Table 4 Main properties of biochar and bio-oil from microwave pyrolysis of corn stover with AC. [^aDry basis, ^bCalculated by difference, ^cDry and ash-free basis, ^dDensity and viscosity at 25 °C, ^eCalculated by HHV (MJ/kg) = 0.3382 C% + 1.4428 (H% − 0.125 O%)].

Proximate analysis (wt%)^a

Volatile matter

30.79 ± 5%

pH value

5.27 ± 3%

Ash

13.18 ± 3%

Dynamic viscosity (mPa.s)^d

2.89 ± 5%

Fixed carbon^b

56.03 ± 3%

Water content (%)

38.92 ± 6%

Ultimate analysis (wt%)^c

Ultimate analysis (wt%)^c

C

71.10 ± 7%

C

31.15 ± 1%

N

0.2 ± 3%

N

0

H

2.7 ± 7%

H

11.24 ± 2%

S

0

S

0

O^b

26 ± 9%

O^b

57.61 ± 2%

Bulk density (kg/m³)

33 ± 3%

Density (g/mL)^d

1.036 ± 1%

HHV (MJ/kg)

25.79 ± 3%

HHV (MJ/kg)^e

16.36 ± 3%

Yield (wt%)

29 ± 2%

Yield (wt%)

45 ± 4%

Energy yield (%)

43.45 ± 2%

Energy yield (%)

43.29 ± 3%