Polydopamine-functionalised biosilica derived from diatomite as a porous composite for effective solid phase extraction of heavy metal ions from aqueous samples

Abstract

ABSTRACT This study aimed to synthesise and apply polydopamine-functionalised biosilica(BS@PDA), derived from diatomite, as a highly porous and biodegradable composite for efficient adsorption of Cu(II), Co(II), Pb(II), and Zn(II) ions from different types of aqueous matrices. The self-polymerisation of dopamine monomers on the treated diatomite’s surface and internal pores was conducted in an aqueous medium at pH = 8.5. The adsorbent’s structural characterisation was evaluated using FT-IR, SEM, EDX, TEM, BET, and BJH confirming a successful synthesis. The effects of critical parameters influencing the quantitative extraction and determination of analytes were optimised. The effects of interfering ions commonly found in industrial and environmental waters were also examined, indicating no severe interference in the extraction process. The calibration curves in the range of 10–500 ng/mL (r ≥ 0.9960) were linear. The relative standard deviations (n = 5) at two different concentration levels were in the range of 2.1–6.2%. The limits of detection of analytes ranged from 0.24 to 1.25 ng/mL. The bio-adsorbent ability to extract the studied analytes was tested in the industrial wastewater, river water, and seawater samples. The recoveries of the spiked analytes in the real samples were above 94%. The results indicated the comparable capacity of the proposed method for both removal and determination of heavy metals in industrial and environmental water samples.