Green synthesized silver nanoparticle modified carbon paste electrode for SWAS voltammetric simultaneous determination of Cd(II) and Pb(II) in Bahir Dar Textile discharged effluent

The principal objective of this research was to demonstrate the sensitivity and selectivity of carbon paste electrode modified with Ocimum Sanctum leaf extract synthesized silver nanoparticles for simultaneous determination of Cd(II) and Pb(II) in discharged textile effluent. While UV-Vis, XRD and FT-IR were used to fully characterize the green synthesized silver nanoparticles, cyclic voltammetry was used to evaluate the electrochemical behavior of the two metals at the modified electrode relative to the unmodified electrode. Square wave anodic stripping (SWAS) voltammetric current showed linear dependence on the concentration in the range 5-160 ppm with determination coefficients (R-2) of 0.9976 and 0.9996 for Cd(II) and Pb(II), respectively. The method also showed extremely low detection limit (0.0891ppm for Cd(II) and 0.048 ppm for Pb(II)) making the method superior over the previously reported methods. Recovery results of 94.3 for Cd(II) and 101.0% for Pb(II) validated the applicability of the method for simultaneous determination of the two metals in a complex matrix textile effluent sample. While levels of Pb(II) and Cd(II) in the untreated sample were 117.0 and 128.3 ppm, their levels in the treated sample were 17.7 and 101.4 ppm, respectively confirming the low efficiency of the treatment plant the factory claims to have. The level of the studied metals in the discharged effluent is much higher than the permissible limit indicating extent of pollution of the water system to which the effluent is discharged.