Preparation, characterization, adsorptive and antimicrobial properties of Fe3O4@SiO2@ZnO nanocomposite
Elijah Yanda Shaba, Jimoh Oladejo Tijani, John Jacob, Mohammed Suleiman, John Tsado Mathew
Abstract
A wide range of toxic contaminants, including hydrocarbons, mercaptans, phenol , ammonia and sulfide found in the wastewater from petroleum refineries have diverse health effects on human and aquatic species . In this work, the sequestration of COD and BOD from petroleum refinery wastewater by Fe 3 O 4 @SiO 2 @ZnO nanoabsorbent prepared at different mole ratios (1:1:1, 1:1:2, 1:2:1 and 2:1:1) was carried out via the batch adsorption method. The nanomaterials synthesized by a combination of sol-gel and wet impregnation techniques were characterized using FTIR, HRSEM, EDS , XPS, XRD , DLS and BET. The HRSEM result revealed a rod-like formation with little spherical shapes on the surfaces regardless of the mixing ratios. Based on the XRD analysis SiO 2 and ZnO maintained their phases while that of Fe 3 O 4 nanoparticles changed with respect to the mixing ratios. BET analysis confirmed higher surface area for Fe 3 O 4 @SiO 2 @ZnO prepared with a mixing ratio of 1:2:1 (35.469 m²/g) as compared to 24.918, 30.685, 15.751 m²/g obtained for other mixing ratios (1:1:1, 1:1:2 and 2:1:1). The maximum removal efficiencies of COD and BOD at a contact time of 15 min, a dosage of 0.08 g, at 30 °C and a stirring speed of 250 rpm were 98.19% and 92.19%. The adsorption of COD and BOD at different temperatures using all the nanoadsorbent irrespective of the mixing ratios were endothermic in nature and Langmuir isotherm and pseudo-second-order kinetic model provided the best description of the experimental data, indicating the chemical adsorption process. The regeneration studies after ten adsorption-desorption cycles indicated that the adsorbent could successfully remove COD (51.06%) and BOD (45.56%). The Fe 3 O 4 /SiO 2 /ZnO nanocomposites (1:2:1) nanoparticles was found to exhibit the greatest antimicrobial activity with 29.50 mm zone of inhibition against Salmonella typhi , 25.00 mm, 26.00 mm zone of inhibition obtained for Escherichia coli and Klebsiella pneumoniae compared to others prepared with different mixing ratios. This study demonstrated that Fe 3 O 4 @SiO 2 @ZnO nanocomposites with a mixing ratio (1:2:1) possesses excellent adsorptive, antimicrobial and recyclability properties