Pseudo Second Order

The linearised form of pseudo second order is shown in Figs. 42, 43, 44, 45, 46 and 47. The computed results of K2, h and qt obtained from the second-order

Fig. 46 The linearized pseudo second order kinetics of RR158 by CAC's. Experimental conditions: room temperature; agitation rate: 200 rpm; biomass dosage: 17.5 g/L; pH: 2
Fig. 47 The linearized pseudo second order kinetics of RR158 by CAC's. Experimental conditions: room temperature; agitation rate: 200 rpm; biomass dosage: 20 g/L; pH: 2

equation are listed in Table 11. The correlation coefficients for the second-order kinetic equation were higher than 0.85 for the batch experiments carried out which indicated that pseudo second order fitted more aptly to pseudo first order. The calculated qt values predicted from the model agreed very well with the experimental data for example at adsorbent dosage of 7.5 and 20 g/L but with a

Table 11 Summary of results for pseudo second order model

Dye concentration

R2

Theoretical qc

Experimental qe

h

*2(g/

(mg/L)

values

(mg/g)

(mg/g)

mg min)

Adsorbent dosage:

7.5 g/L

20

0.971

0.3279

0.348

-0.0569

-0.5295

40

0.972

0.8078

0.668

0.0352

0.0540

60

0.999

1.9417

1.881

0.6321

0.1677

80

0.999

1.9724

1.941

1.1086

0.2850

100

0.995

2.4570

2.296

0.2990

0.0495

120

0.999

4.5872

4.407

0.8881

0.0422

Adsorbent dosage:

10 g/L

20

0.997

0.4575

0.394

0.0525

0.2511

40

0.069

1.6313

0.444

0.0053

0.0020

60

0.785

0.9407

0.667

0.0301

0.0341

80

0.997

1.7452

1.533

0.3007

0.0987

100

0.997

3.2362

2.894

1.1074

0.1057

120

0.999

3.4965

3.311

0.9066

0.0742

Adsorbent dosage:

12.5 g/L

20

0.692

0.4895

0.391

0.0171

0.0713

40

0.226

4.6083

1.422

0.0187

0.0009

60

0.969

1.3477

1.120

0.0750

0.0413

80

0.954

0.1898

0.809

0.0016

0.0457

100

0.880

1.9646

1.498

0.2642

0.0684

120

0.336

3.7037

1.267

0.0281

0.0020

Adsorbent dosage:

15 g/L

20

0.766

0.4277

0.293

0.0152

0.0831

40

0.942

2.1008

0.937

0.0132

0.0030

60

0.996

1.4925

1.378

0.2196

0.0986

80

0.984

1.0482

1.019

0.2402

0.2186

100

0.018

8.3333

1.652

0.0184

0.0003

120

0.996

1.7271

1.307

0.2846

0.0954

Adsorbent dosage:

17.5 g/L

20

0.099

3.2895

0.698

0.0087

0.0008

40

0.030

3.6364

0.911

0.0099

0.0007

60

0.984

1.0549

1.022

0.3246

0.2917

80

0.970

1.0661

1.076

-0.7289

-0.6413

100

0.985

1.2210

1.130

0.4751

0.3187

120

0.891

1.7422

0.876

0.0641

0.0211

Adsorbent dosage:

20 g/L

20

0.757

2.7248

1.770

0.0420

0.0057

40

0.680

5.8824

2.533

0.0399

0.0012

60

0.913

4.1322

3.289

0.1378

0.0081

80

0.693

6.0606

3.459

0.0715

0.0019

100

0.930

3.8168

2.556

0.2938

0.0202

120

0.986

4.4444

4.052

0.7987

0.0404

Log t

Fig. 48 The linearized intra particle diffusion adsorption isotherms of RR158 by CAC's. Experimental conditions: room temperature; agitation rate: 200 rpm; biomass dosage: 7.5 g/L; pH: 2

Log t

Fig. 48 The linearized intra particle diffusion adsorption isotherms of RR158 by CAC's. Experimental conditions: room temperature; agitation rate: 200 rpm; biomass dosage: 7.5 g/L; pH: 2

few exceptions certain dosages of adsorbent. These indicated that the adsorption system studied was very consistent with the second-order kinetic model. The second-order rate constant K2 was in the range of 0.0003-0.2917 g/(mg) (min) at the given initial dye concentrations while the predicted values of h were in the range of 0.0053-1.1086 mg/g min for the batch experiments carried out.

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