PAPERmaking! Vol7 Nr3 2021

Cellulose (2021) 28:10183–10201

10193

Table 4 Summary of nonlinear regression results for Langmuir isotherm and Freundlich isotherm at 25  Cand35  C with unrefined and refined NBSK pulp. Isotherm Temperature (  C) Refining (rev) R 2 adj Q max (mg  g - 1 ) K e (L  mg - 1 ) Reduced chi-squared v 2 (mg 2  g - 2 )

Langmuir 25

0

0.46 2.34 ± 0.20

2.82 ± 1.73 0.13

35

0

0.95 6.31 ± 0.75

0.16 ± 0.06 0.16

25

3000

0.73 3.87 ± 1.28

3.75 ± 6.50 0.33

Isotherm Temperature (  C) Refining (rev)

Reduced chi-squared v 2 (mg 2  g - 2 )

K f (mg  g - 1  (mg  L - 1 ) - 1/n )

R 2

n

adj

Freundlich 25

0

0.38 12.82 ± 7.09 1.70 ± 0.25 0.15

35

0

0.94 2.71 ± 0.50 1.48 ± 0.31 0.19

25

3000

0.99 5.00 ± 0.04 2.57 ± 0.01 0.00

95% confidence limits after ±

7

3.5

(a)

25 o C unrefined

(b)

35 o C unrefined

6

3.0

5

2.5

4

2.0

3

1.5

2

1.0

Experimental Langmuir Freundlich

Experimental Langmuir Freundlich

1

0.5

0

0.0

0

10

20

30

40

50

0

20

40

60

80

100

C e (mg/L)

C e (mg/L)

5

(c)

25 o C refined

4

3

2

Experimental Langmuir Freundlich

1

0

-2 0

2

4

6

8 10 12 14

C e (mg/L)

Fig. 4 Nonlinear fit of Langmuir model and Freundlich model with experimental results at a 25  Cand b 35  C of LBG adsorption to unrefined NBSK pulp, and at c 25  C of LBG adsorption to refined NBSK pulp (3000 rev)

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