RESUMO
The refinery industry has witnessed tremendous activity aimed at producing petrochemicals for the benefit of the teeming populace. These activities are accompanied by the discharge of wastewater containing chemical substances and elements that have negative impacts on the ecosystem. The presence of phenol and cyanide contaminants in refinery wastewater poses serious health hazards to humans, necessitating their removal. In this study, boron oxide-doped multi-walled carbon nanotubes (B2O3/MWCNTs) and titanium boride-doped MWCNT (TiB/MWCNTs) nanoadsorbents were prepared via a wet impregnation method and characterized using High-Resolution Transmission Electron Microscopy (HR-TEM), X-Ray Diffraction (XRD), and X-ray Photoelectron Spectroscopy (XPS). HR-TEM images depict the nanostructure of the nanoadsorbent, the presence of doped materials, and the internal, external, and wall thickness of B2O3/MWCNTs and TiB/MWCNTs nanoadsorbents. XRD results indicate that the nanomaterials were monocrystalline with average crystallite sizes of 22.75 nm and 16.79 nm for B2O3/MWCNTs and TiB/MWCNTs, respectively. The formation of B2O3 and TiB was observable in the results obtained from the XPS at the binding energy of 192 and 193.1 eV, respectively. The application of the produced B2O3/MWCNTs and TiB/MWCNTs nanoadsorbents for the removal of phenol and cyanide from refinery wastewater was explored in a batch adsorption system. The effects of contact time, adsorbent dosage, and adsorption temperature were investigated. To the best of our knowledge, the incorporation of B2O3 and TiB in MWCNTs resulted in the highest adsorption capacities for phenol and cyanide from aqueous solutions. The highest percentage removal of 100% for phenol and 99.06% for cyanide was observed for the TiB/MWCNTs nanoadsorbent at a residence time of 70 minutes, a temperature of 60 °C, and 0.3 g of adsorbent. The isotherm models show that cyanide and phenol removal obeyed the Langmuir isotherm, indicating monolayer adsorption over B2O3/MWCNTs nanoadsorbent. Furthermore, cyanide and phenol removal depict multilayer adsorption on the TiB/MWCNT nanoadsorbent. The research shows that B2O3/MWCNTs are proficient in cyanide sorption, while TiB/MWCNT favors phenol sorption due to their respective adsorption capacities.
RESUMO
Zinc coating is one of the oldest types of coating for mild steel. The main drawback of zinc coating is that the steel loses its zinc ion after being exposed to environmental factors, leaving mild steel vulnerable to corrosion. Researchers have been working hard to create a zinc-based coating using co-deposition with agricultural waste. The outcome of this co-deposition is increased wear resistance, increased hardness, improved oxidation stability, and improved corrosion resistance. This work aims to enhance the oxidation, wear, and corrosion resistance of mild steel by co-deposition of zinc and maize cob ash nanoparticles. 0, 5, 10, and 15 wt% maize cob ash nanoparticles were used in the production of the coating. Scanning electron microscopy was used to characterize the materials' microstructure. The resulting coated samples' hardness, wear, oxidation, and corrosion properties were examined. The hardness parameters increased by 74.89% and the protection against corrosion by 76.6%. It has been shown that mild steel may have its corrosion, wear, and oxidation resistance increased by using 15 wt% maize cob ash particles.