DEPARTMENT OF CHEMICAL ENGINEERING

This study investigates the use of guava leaf extract (Psidium guajava) as an organic corrosion inhibitor for low-carbon steel in a carbonic medium. Corrosion of steel remains a critical global issue, with its annual cost estimated to exceed $2.5 trillion, representing approximately 3.4% of the world’s GDP. This necessitates an environmentally friendly alternative to traditional toxic synthetic inhibitors. The research method involved preparing the extract and conducting corrosion tests on mild steel coupons (with a carbon content of less than 0.25%). Experiments were carried out in a 1M HCl acidic medium using techniques such as weight loss measurements, potential dynamic polarization, and EIS, across a temperature range of 25–60°C and a pH range of 2–6. The study focused on short-term exposure (up to 24 hours) to assess the initial inhibition efficiency. The guava leaf extract proved to be a highly effective inhibitor. Statistical validation via ANOVA established the model's significance with an extremely high Model F-value of 921.10 and a p-value of < 0.0001 for Inhibition Efficiency. The predictive power was robust, as indicated by a Predicted R² of 0.9945 being in reasonable agreement with the Adjusted R² of 0.9978 , and an Adequate Precision ratio of 79.032. Time and Temperature were confirmed as the only statistically significant model terms, suggesting the corrosion process is under kinetic control. The numerical optimization demonstrated that a near-maximum predicted efficiency could be achieved at the lowest inhibitor dosage, supporting the extract's high potency and cost-effectiveness. In conclusion, the guava leaf extract successfully performed as an environmentally sustainable corrosion inhibitor. The inhibition mechanism was determined to be chemisorption, driven by the active phenolic groups and aromatic rings in the extract, which form a compact protective barrier on the steel surface.

For its bio- and environmentally friendly properties, low cost, and relative abundance, clay has become increasingly relevant and used. Based on their components and layer patterns, clay minerals have a variety of morphological and physicochemical characteristics., in addition to its well-established uses in adsorbent development, water treatment, and construction. In order to determine whether clay samples from the Ikpeshi town in the Akoko-Edo LGA could be used in an industrial process, its physical and chemical characteristics were examined. The study involved the analysis of elemental content, mineral constituent, functional groups of compounds content, surface morphology, and thermal stability with EDXRF, XRD, FTIR, SEM, BET and TGA respectively. Results revealed that the sample was kaolinite with SiO2 45.116 wt%, and Al2O3 20.39 wt% as the most predominant elements. Wave numbers of 909.47043cm-1 to 998.92654cm-1 with bold peaks revealed the presence of SiO4 -4 . The overall study revealed kaolinite characteristics and strong thermal stability thus possesses properties for clay suitable for lining furnace kilns.

This study addresses the growing demand for renewable energy and sustainable chemical processes by investigating the production of a novel, bifunctional heterogeneous catalyst derived from readily available waste banana peels, zeolite, and periwinkle shells for biodiesel synthesis. The methodology involved systematic catalyst synthesis from the three precursor materials through calcination at 800°C for 3 hours, followed by characterization using X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy to confirm Ca–Si–Ti oxide phase formation and identify crystalline structures contributing to catalytic activity. Feedstock physicochemical properties including acid value, iodine value, saponification value, density, and viscosity were determined. Simplex lattice mixture design optimized the neem oil-waste cooking oil blending ratio for maximum free fatty acid reduction. The transesterification process employed response surface methodology (RSM) with 29 experimental runs to optimize reaction parameters: time (30–150 minutes), temperature (40–80°C), catalyst loading (1–10 wt%), and methanol-to-oil ratio (3:1–10:1). Kinetic studies determined reaction order and activation energy, while gas chromatography-mass spectrometry (GC-MS) analyzed the fatty acid methyl ester (FAME) composition of the produced biodiesel.

Produced water, a major byproduct of petroleum extraction, contains a complex mixture of organic and inorganic contaminants such as hydrocarbons, heavy metals, and suspended solids, which pose severe environmental risks if discharged untreated. Conventional treatment methods are often expensive and inefficient in achieving complete degradation of such pollutants. This study investigates the photodegradation of produced water using bentonite clay doped with titanium dioxide (TiO₂) as an efficient and eco-friendly treatment approach. The bentonite–TiO₂ composite was synthesized and characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X ray Fluorescence (XRF) to determine its structural and morphological properties. Photocatalytic degradation experiments were performed with a photocatalytic reactor, utilizing natural sunlight as the irradiation source varying operational parameters such as pH, contact time, and catalyst dosage (2–10 g). The treatment performance was evaluated using Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) analyses before and after photodegradation. Results showed a consistent decrease in both BOD and COD values with increasing catalyst dosage from 8.13 to 3.55 mg/L (BOD) and 5270 to 1420 mg/L (COD) representing approximately 56% and 73% reductions, respectively. This demonstrates the effectiveness of the TiO₂–bentonite composite in degrading organic pollutants in produced water.