Kinetic models      Initial naphthalene concentration
  10              20            30           40          50
             pH
  5              7             9
Lagergren
             Kad (h-1)
             qm (mg/g)
             R2
  0.032
0.417
0.999
  0.032
0.921
0.996
  0.032
1.42
0.999
  0.032
1.73
0.998
  0.032
2.07
0.998
  0.035
1.11
0.997
  0.032
1.42
0.999
  0.035
1.25
0.996
Elovich
          α (mg/g/min)
           β (g/mg)
            R2
  0.007
6.45
0.901
  0.008
2.73
0.929
  0.010
1.81
0.921
  0.016
1.49
0.914
  0.020
1.24
0.916
  0.007
2.41
0.921
  0.010
1.81
0.921
  0.008
2.13
0.921
Intraparticle diffusion
      Kp (mg/g/min)
            R2
  0.008
0.948
  0.018
0.951
  0.027
0.952
  0.033
0.949
  0.040
0.949
  0.020
0.952
  0.027
0.952
  0.023
0.952
Table 5: Kinetic constant parameters for the adsorption of naphthalene by orange peels for various initial concentration and pH.