Separation and preconcentration of Pb(II), Cd(II) and Pd(II) ions from environmental samples by solid phase extraction: Development of new adsorbents and chemometric applications

In this thesis, novel adsorbents were developed for the recovery and determination of Pb(II), Cd(II), and Pd(II) ions from environmental samples by solid-phase extraction (KFE). For this purpose, dead cells of Salmonella Typhimurium ATCC 23566, Enterococcus faecalis ATCC 29212, and Pseudomonas aeruginosa ATCC 27853 were immobilized onto Fe₃O₄ and NiFe₂O₄ nanoparticles synthesized via the co-precipitation method. The obtained adsorbents were characterized using FTIR, SEM-EDX, TEM, XRD, and BET analyses. Analytical parameters affecting the adsorption and desorption efficiencies—such as pH, adsorbent dosage, adsorption/desorption time, and eluent concentration—were optimized using a chemometric approach based on Central Composite Design (CCD). Also, Artificial Neural Network (ANN) models were established to predict metal ion recovery. The effects of common cations and anions present in the matrix on the recovery of the analytes were also examined. The enrichment factors of the developed methods were found to be 80 for Pb(II) and 40 for both Pd(II) and Cd(II). The limits of detection ranged from 0.68 to 4.41 µg/L, and the relative standard deviations were between 1.59 and 2.09%. The accuracy of the proposed methods was verified through spike/recovery tests conducted on river water, seawater, soil, acid mine drainage, parsley, mint, and red pepper samples.