Table 5 Concentration of surface functional groups by Boehm titration.

From: Twigs-derived activated carbons via H3PO4/ZnCl2 composite activation for methylene blue and congo red dyes removal

Activated carbon

Carboxylic groups (mmol/g)

Lactonic groups (mmol/g)

Phenolic groups (mmol/g)

Total acidic sites (mmol/g)

Total basic sites (mmol/g)

TAC1

0.20

0.05

0.10

0.35

0.761

TAC2

0.30

0.00

0.35

0.65

0.217

TAC3

0.70

0.00

0.45

1.15

0.109

TAC4

0.25

0.15

0.40

0.80

0.000

TAC5

0.50

0.00

0.35

0.85

0.000

TAC6

0.35

0.00

0.25

0.60

0.326