Photocatalytic, Electrochemical, Antibacterial and Antioxidant Behaviour of Carbon-Sulphur Co-doped Zirconium (IV) Oxide nanocomposite.

Abstract

In this work, carbon-sulphur co-doped ZrO 2 nanocomposites were synthesised using the aqueous leaves extract of Plumeria acuminate, zirconia salt precursor, polyvinylpyrrolidone and sodium hydrosulphide. The structural, elemental and morphological properties of the synthesized nanomaterials were examined by different analytical techniques UV-visible spectrophotometer, HRSEM-EDS, HRTEM-SAED, XRD and BET. HRSEM analysis of C-S- ZrO 2 revealed the presence of spherical and irregular hexagonal shapes. The XRD pattern demonstrated formation of crystalline tetragonal and a mixture of tetragonal and orthorhombic phases for ZrO 2 and C-S-ZrO 2 composite with an average size of 20.03 nm and 12.40 nm respectively. The band gap values of 5.2 eV and 3.4 eV were ob- tained for ZrO 2 and C-S-ZrO 2 respectively. The adsorptive and photocatalytic properties of ZrO 2 based nanomate- rials for the removal of azo dye in local dyeing wastewater were investigated. The electrochemical activities of the nanomaterials were assessed using cyclic voltammetry, while Agar well diffusion, DPPH and ABTS methods were followed for the determination of antibacterial and antioxidant activities of ZrO 2 and C-S-ZrO 2 . The maximum COD, BOD, TOC, SO 4 2-, CO 3 2, Cl − and NO 3 − removal efficiencies of 77.3%, 87.6%, 97.7% 63.9%, 84.4%, 70.3% and 83.3 % at 120 min were obtained using C-S-ZrO 2 composite due to its higher surface area (80.165 m 2 /g) and lower band gap (3.4 eV) compared with ZrO 2 (10.682 m 2 /g). Carbon-sulphur co-doped ZrO 2 composite exhibited moderate antioxidant activity and increased peak current than other ZrO 2 based nanomaterials due to its high- est surface area than ZrO 2 alone. The order of antibacterial activity of the nanomaterials against the Salmonella typhi, Pseudomonas aeruginosa, Escherichia coli is ZrO 2 -C-S (15.40 ± 1.11 mm, 25.10 ± 1.80 mm, 20.03 ± 2.50 mm) > C-ZrO 2 (9.45 ± 2.65 mm, 11.18 ± 0.33 mm, 15.45 ± 3.25 mm) > S-ZrO 2 (7.52 ± 1.55 mm, 12.45 ± 0.11 mm, nil) > ZrO 2 (6.33 ± 0.90 mm, 4.25 ± 0.52 mm, nil). The experimental data best described by pseudo-first-order, fol- lowed by parabolic-diffusion and modified Freundlich models. The results showed that the synthesized C-S-ZrO 2 nanocomposite is highly efficient with excellent regenerative potential even after five cycles.