Synthesis of g-C3N4-PDA as a new adsorbent for efficient micro extraction of Pb(II) and Cu(II) metal ions: Optimization by multivariate analysis

Due to the growth of industry, environmental pollution by heavy metal ions have increased [1]. Copper and lead are two common types of heavy metals that even at low concentrations threaten human health [2]. Therefore, the determination of these metals in the environment is very important. There are various methods for separation of these metal ions. The SPE method due to simplicity, high speed, low amounts reagent and also more environmentally friendly, has been very much considered[3]. But, in this method, a completely uniform dispersion of the solid phase in the sample solution is very important. In the present work a new method named effervescent-assisted dispersive micro solid-phase extraction (EA-Dµ-SPE) was used. In this method due to used the solid effervescent agents in sample solution,the interactions between co-polymer with analyte was increased that lead to the dispersion of the adsorbent occurs in a short times. As the result, the extraction efficiency was increased. In this work, a graphitic carbon nitride modified with polydopamine (g-C3N4-PDA) was successfully synthesized, and used for extraction of the Pb(II) and Cu(II) ions by using effervescence-assisted dispersive micro-solid phase method. The structure of the g-C3N4-PDA co-polymer was corroborated by FT-IR, XRD, FE-SEM analysis.Then, the extraction ions were quantified by micro sampling-flame atomic absorption spectrometry ( µS-FAAS). The limits of detection (LODs) was obtained 0.16 and 0.06 μgL−1 for Pb(II) and Cu(II), respectively. Also, the relative standard deviations (%RSDs, for n = 3) was obtained 1.14 and 1.2% for Pb(II) and Cu(II), respectively. In addition to, the adsorbent was reused for 8 times with negligible changes in the extraction recoveries (more than 99%). In order to achieve optimal conditions, the central composite design (CCD) method was used as a statistical method. This method was also applied successfully for the simultaneous detection of the Pb(II) and Cu(II) ions in the real samples of water and sunflower oil.