Organic ligands as adsorbent surface of heavy metals and evaluating antibacterial activity of synthesized complexes

[Display omitted] •The experimental evaluation focuses on determining the adsorption efficiency of a bi-dentate Schiff base ligand compound and a tetra-dentate Schiff base ligand compound for removing heavy metals.•Using a bi-dentate Schiff base ligand, the adsorption efficiency for Zn(II), Hg(II), and Cd(II) ranges from 78% to 90%.•Using tetra-dentate Schiff base ligands, the adsorption efficiency for Zn(II), Hg(II), and Cd(II) ranges from 92% to 98%.•In comparison to the first ligand, the tetra-dentate Schiff base ligands exhibit notable biological activity against four types of bacteria, resulting in inhibition diameters ranging between 0.5 and 2.5 cm. Schiff base ligand is prepared by the reaction of salicylaldehyde with o- phenylene diamine. The prepared ligand has been characterized by FT-IR spectroscopy. The adsorption treatment of heavy metals in their solutions is utilised in this study via experimentally preparing three complexes including [Hg (C6H8N2)3]Cl2, [Zn (C6H8N2)3]Cl2, and [Cd (C6H8N2)3]Cl2 using (ortho-phenylenediamine) as a bi dentate Schiff base ligand. The ligand is used as a chemical adsorbate to coordinated with heavy metals that found in chemical coating solutions and to generate octahedral complexes. In this regard, the adsorption efficiency of the associated heavy metals (Zn(II), Hg (II), and Cd (II)) is investigated between 78% and 90% as evidenced by the extremely effective flame atomic absorption (AAS). To systematically improve the adsorption efficiency of the associated heavy metals, another set of three Schiff base compounds with a tetra dentate ligand are prepared to forming three complexes of [Zn(C20H16N2O2)]Cl2 [Hg(C20H16N2O2)]Cl2, and [Cd(C20H16N2O2)]Cl2. In turn, these complexes are used as adsorbate layers to recover the heavy metals from their solutions. The adsorption efficiency is improved to be between 92% and 98 %, which indicates an excellent chemical adsorption process for recovering the three heavy elements used in this study. The biological activity of the used ligands and all the complexes prepared with different concentrations (0.1–0.01 M) against four types of bacteria (K. pneumoniae, E. coli, S. aureus, S. epidermidis) is also measured as part of this study. The first ligand (ortho-phenylene diamine) has no biological activity against these four types, whereas the complexes prepared in the preceding two steps are all effective, with inhibition diameters ranging between 0.5 and 2.5 cm.