Table 8 Intraparticle diffusion and Boyd’s kinetics constants.

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

Activated carbon

Co (mg/L)

Qe,exp (mg/g)

Intraparticle diffusion model

Boyd’s model

kd (mg/g min)

C (mg/g)

R2

Intercept

Di (cm2/s)

R2

Methylene blue

TAC2

20

19.9

0.147

17.0

0.8118

1.22

5.73 × 10–9

0.9355

100

95.6

0.982

71.9

0.8178

0.95

7.17 × 10–9

0.9521

TAC3

20

19.8

0.176

15.9

0.8583

1.02

5.73 × 10–9

0.9488

100

89.9

0.994

64.4

0.9395

0.59

7.17 × 10–9

0.9638

TAC4

20

15.6

0.177

10.9

0.7714

0.65

5.73 × 10–9

0.9066

TAC5

20

18.4

0.289

11.1

0.8027

0.69

5.02 × 10–9

0.9650

TAC6

20

19.8

0.260

13.3

0.7852

0.78

5.73 × 10–9

0.9661

Congo red

TAC2

20

17.0

0.489

2.89

0.9340

0.12

4.30 × 10–9

0.9829

TAC3

20

17.8

0.424

5.50

0.9313

0.29

4.30 × 10–9

0.9855

TAC4

20

14.9

0.461

1.23

0.9636

0.05

4.30 × 10–9

0.9670

TAC5

20

19.6

0.438

7.50

0.8788

0.36

5.02 × 10–9

0.9830

100

76.1

1.368

38.5

0.8371

0.55

4.30 × 10–9

0.9537

TAC6

20

18.5

0.523

3.78

0.9026

0.17

5.02 × 10–9

0.9945

100

66.8

1.719

18.5

0.9027

0.07

6.45 × 10–9

0.8915