Pb(II) solid-phase extraction in wastewater samples prior to flame atomic absorption spectrometry analysis using chitosan and alginate modified carbon

The sustainability concept was kept in view by designing and synthesising a novel adsorbent for Pb(II) ion, using natural and metal-free precursors which are renewable and biodegradable, i.e. alginate, chitosan, and carbon. The study was aimed to introduce the synthesis of Carbon/Alginate/Chitosan composite (CAC) as a beneficial adsorbent tailored for the solid-phase extraction (SPE) of Pb(II) prior to its analysis via flame atomic absorption spectrometry (FAAS). The successful preparation of the CAC material is elucidated, characterised through FTIR for functional group analysis, and evaluated for surface morphology and elemental composition via SEM-EDX. Optimisation of SPE parameters was carefully conducted to enhance adsorption-desorption efficiency across diverse conditions. These optimised factors were a pH level of 6, initial Pb(II) concentration of 20 mg/L, sample flow rate 5 mL/min, elution utilising Na2EDTA at a rate of 5 mL/min, sample volume of 20 mL, Na2EDTA eluent volume of 10 mL, and Na eluent concentration of 0.5 M. Application of CAC-based SPE for Pb(II) analysis in wastewater samples under these optimised conditions yielded exceptional recovery rates of 93–96%, with a limit of detection (LoD) value of 71.4 µg/L. Moreover, a notable preconcentration factor of 4–8 times is achieved for Pb(II) in wastewater samples, facilitating the detection of Pb(II) concentrations as low as 30 µg/L.