First-order kinetic equation   CNT M CNT -HNO3 qe,exp(mg/g) 1.74 8.96 q1 (mg/g) 0.3 1.2 k1 (min-1)×10-3 4.61 4.33 R21 0.7172 0.8033 Second-order kinetic equation q2 (mg/g) 1.7385 8.9598 k2 0.0541 0.018 [g/(mg min)]×10-3     R22 0.99918 0.99987 Intraparticle diffusion equation kint 0.00645 0.03655 [mg/(g min1/2)]     C 1.52197 7.86686 R2int 0.74589 0.82195 Boyd equation Intercept 1.265 0.448 R2 0.71747 0.8039

Table 4: Kinetic parameters for the adsorption of for Cd(II) adsorption CNT and MCNT-HNO3.