Table 2 Adsorption kinetic and diffusion model constants for MB removal using pure diatomaceous mesoporous biosilica.

From: A novel effective bio-originated methylene blue adsorbent: the porous biosilica from three marine diatom strains of Nanofrustulum spp. (Bacillariophyta)

Kinetic model

Pseudo-first order

Pseudo-second order

Elovich

 

q1, mg g−1

k1, min−1

R2

Δq, %

q2, mg g−1

k2, g (mg min)−1

R2

Δq, %

α, g (mg min)−1

β, mg g−1

R2

Δq, %

 

SZCZCH193

19.902

0.002

0.887

52.2

39.671

2.71e−5

0.894

65.4

0.042

0.051

0.893

64.7

 

SZCZM1342

9.445

0.991

0.979

26.9

14.787

4.09e−4

0.964

28.2

0.094

0.178

0.969

29.6

 

SZCZP1809

8.458

0.987

0.989

24.1

12.283

7.74e−4

0.973

28.9

0.130

0.237

0.976

32.3

 

Diffusion model

Intra-particle (Weber-Morris)

Bangham’s pore diffusion

     

Kwm, mg (g min 0.5)−1

B, mg g−1

R2

Δq, %

Δβ

Kβ

R2

Δq, %

     

SZCZCH193

0.377

1e−16

0.730

52.2

1.374

0.004

0.972

18.2

     

SZCZM1342

0.535

1e−14

0.901

26.9

1.025

0.037

0.964

13.9

     

SZCZP1809

0.575

1e−14

0.930

24.1

1.073

0.035

0.985

19.2

     

Isotherm

Langmuir

Freundlich

Sips

Q0max, mg g−1

KL, L mg−1

R2

Δq, %

KF, (mg g−1) (mg L−1)−n

n

R2

Δq, %

qm, mg g−1

KS, [(mg L−1)−1/n]

n

R2

Δq, %

SZCZCH193

6.85

0.31

0.965

11.9

2.37

0.27

0.953

19.6

8.39

0.16

0.65

0.992

7.2

SZCZM1342

16.18

1.35

0.959

48.9

1.88

1.10

0.965

36.3

19.02

0.26

2.26

0.998

6.5

SZCZP1809

27.09

0.24

0.879

 > 100

4.94

0.67

0.820

 > 100

15.17

0.75

2.87

0.999

20.9