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-½)             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.