Material and methods Preparation of heavy metal solutions The 100 ppm stock solutions of C d2+, Pb2+, Zn2+, Ni2+, Fe3+ and AsO43− ions were prepared by using CdCl2, Pb(NO3)2, Zn(CH3COO)2, Ni(NO3)2.6H2O, FeCl3·6H2O and Na2HAsO4...