Fabrication of versatile Ag-P/Ppy core-shell nanocomposite: Adsorption efficacy for chromium (VI) removal and assessment of antioxidant and antibacterial activities

Abstract

This study reports the synthesis, via in-situ chemical oxidative polymerisation, of conducting polymer-based silver phosphate Polypyrrole (Ag-P/Ppy) core-shell nanocomposite, exhibiting antioxidant and antibacterial characteristics, for the adsorption of chromium (VI) ions from aqueous solutions. Filtering away Cr (VI) ions efficiently also improves the filtered water with antibacterial and antioxidant properties. P-XRD, ATR-FTIR, FESEM, EDAX, TEM, zeta potential, TGA, and BET studies characterized Ag-P/Ppy. The core-shell nanostructure of Ag-P/Ppy was determined by TEM micrographs, which indicated the presence of an Ag-P core and a Ppy shell. pH value, adsorbent dose, stirring rate, contact time, and Cr (VI) pollutant concentration, were investigated as potential influencing factors. At pH 2, 99.4 % of Cr(VI) was removed in 55 min. The adsorption kinetics was effectively depicted by a pseudo-second-order kinetics model, signifying that chemisorption played a momentous role in the total adsorption capacity. Freundlich, Temkin, Redlich-Peterson, and Sips isotherm models were fitted to adsorption data. Temkin and Redlich-Peterson models have a higher (0.99) correlation coefficient than Freundlich (0.95) and Sips (0.98). The maximum adsorption capacity (qm) evaluated using the Sips model was 138.5 mg g−1, which was quite close to the 130.55 mg g−1 value obtained from experiments. The manufactured nanocomposite showed 91.2 % radical scavenging activity in a 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay. Antibacterial activity of the Ag-p/Ppy core-shell nanocomposite contrary to gram-positive (S. aureus) and gram-negative (P. aeruginosa, E. coli, and K. pneumoniae) bacteria was assessed by means of the agar well diffusion technique. Compared to the positive control, it inhibited S. aureus, E. coli, K. Pneumoniae, and P. Aeruginosa by 82.35 %, 79.5 %, 63.63 %, and 76.7 % respectively. Therefore, the Ag-P/Ppy core-shell nanocomposite has the potential as a potent and versatile adsorbent for the exclusion of Cr (VI) ions from water.