Immobilization of unmodified aminoanthraquinone derivatives onto silica gel surface for solid-phase extraction and pre-concentration of Pb(II)

In this project, silica gel chemically bonded with derivatives of aminoanthraquinone were synthesized and characterized. Adsorbents 1,8-aminoanthraquinone-3-aminopropylsilica (SL1), 2-aminoanthraquinone-3-aminopropylsilica (SL2) and 1-aminoanthraquinone-3-aminopropylsilica (SL3) were produced and tested to adsorb heavy metal solutions including Pb(II) Cu(II) Zn(II) Cd(II) and Co(II). The concentrations of the adsorbed heavy metals solution were calculated by atomic adsorption spectrophotometry employing a batch method. The results showed that speed at 200 rpm for 30 min with pH 9 is the optimum condition for heavy metal adsorption. The result also indicated that adsorbent SL3 is the best adsorbent for Pb(II) at 82.5%, and the relative standard deviation (R.S.D.) was lower than 6%. The method detection limit was 1.1 µg L⁻¹ for Pb²⁺. In addition, Density Functional Theory (DFT) calculation results suggested that the adsorbent sensor formed stable complexes with Pb(II) through a large number of cation-dipole interactions. The method was also applied with satisfactory results to the pre-concentration of trace Pb(II) in environmental samples.