Preparation and Characterization of Synthetic Heavy Metal- Spiked Water Containing Cd, Cr, Cu, Hg, Ni, Pb, And Zn Using Atomic Absorption Spectroscopy

Abstract

Heavy metal contamination of aquatic environments poses significant environmental and public health challenges due to the persistence, toxicity, and bioaccumulative nature of metal pollutants. This study synthesized, characterized, and evaluated Fe/Mn/N tri-doped sawdust- derived biochar as a sustainable nano-adsorbent for the removal of cadmium (Cd), chromium (Cr), lead (Pb), nickel (Ni), copper (Cu), zinc (Zn), and mercury (Hg) from synthetic heavy metal-spiked water. Sawdust was chemically impregnated with iron, manganese, and nitrogen precursors before pyrolysis at 600 °C to produce the engineered biochar. The synthesized adsorbent was characterized using Fourier Transform Infrared Spectroscopy , Scanning Electron Microscopy , X-ray Fluorescence , and Differential Scanning Calorimetry , while heavy metal concentrations were determined using Atomic Absorption Spectrophotometry . Batch adsorption experiments were conducted to investigate the effects of adsorbent dosage, contact time, pH, and temperature on heavy metal removal, followed by adsorption isotherm, kinetic, and thermodynamic analyses. Characterization confirmed successful incorporation of Fe, Mn, and N into the biochar matrix, resulting in enhanced surface functionality, porosity, and thermal stability. The prepared synthetic wastewater closely matched the target heavy metal concentrations, confirming the reliability of the preparation procedure. Adsorption efficiency increased with adsorbent dosage and contact time, with optimum performance achieved at 1.0 g adsorbent dosage, 60 min contact time, pH 4, and 40 °C. The Freundlich isotherm model best described the adsorption process, indicating heterogeneous multilayer adsorption, while the pseudo- second-order kinetic model suggested chemisorption as the dominant mechanism. Thermodynamic results showed that adsorption was spontaneous and exothermic. Overall, Fe/Mn/N tri-doped sawdust-derived biochar demonstrated excellent adsorption capacity and operational stability, highlighting its potential as a low-cost, environmentally sustainable adsorbent for the treatment of heavy metal-contaminated wastewater.

Keywords

References