Corrosion is a pervasive issue affecting metallic materials, with significant economic losses and safety risks in various industries. Mild steel, extensively used in construction and infrastructure, faces corrosion challenges, needing continuous research to effectively tackle them. Natural compounds, because of their eco-friendliness and corrosion inhibition potential, are attracting increasing interest for corrosion control. Lawsonia inermis (LI), or henna, a plant native to North Africa and South Asia, has bioactive compounds exhibiting corrosion inhibitive properties. This study comprehensively explores Lawsonia inermis’s effectiveness as a corrosion inhibitor for mild steel, filling a gap in the existing research. Various concentrations of Lawsonia inermis extract were tested in acidic solutions to evaluate corrosion inhibition. Experimental results indicate a significant reduction in the corrosion rate with increasing inhibitor concentration. Langmuir adsorption isothermal analyses reveal the adsorption mechanism as being an interplay between physisorption and weak chemisorption. Electrochemical measurements demonstrate Lawsonia inermis’s capability to alter both cathodic and anodic reactions, leading to improved corrosion resistance. Scanning electron microscopy reveals a more even surface morphology in the presence of the Lawsonia inermis, indicating corrosion inhibition. Gas chromatography–mass spectrometry (GC-MS) analyses identified organic compounds in Lawsonia inermis extract responsible for corrosion inhibition. Overall, Lawsonia inermis emerges as a promising corrosion inhibitor for mild steel, offering excellent inhibition efficiencies. This study sheds light on its adsorption behaviour and provides insights into its mechanism of action. These findings underscore Lawsonia inermis’s potential as a green corrosion inhibitor, paving the way for its practical application in industrial corrosion protection strategies.

The study aimed at evaluating the potential of Hibiscus sabdariffa leaf extract (HSLE) to retard the corrosion of aluminum in 0.1 M and 1 M HCl. Weight loss measurements and potentiodynamic polarization techniques were employed for the study. The mechanism of corrosion was also determined using Langmuir adsorption isotherm. Ethanolic extracts of Hibiscus sabdariffa leaves were obtained and used to prepare different concentrations ranging from 500 mg/L to 3000 mg/L and corrosion rate measurements were taken over time intervals of 24-120 hours for mild steel immersed in 0.1 M and 1 M HCl in the presence and absence of HSLE. The results showed that HSLE is a good inhibitor of aluminum corrosion under the studied conditions. Excellent inhibition efficiencies of 95.1 % and 96.2 % were obtained for 0.1 M and 1 M HCl respectively. The corrosion rate was retarded with an increase in concentration of HSLE and almost approached zero at 24 hours for 1 M HCl and at 96 and 120 hours for 0.1 M HCl. The mechanism of corrosion inhibition was physiosorption. Electrochemical result showed HSLE as a mixed-type inhibitor, retarding the corrosion potential and current density, and shifting the cathodic and anodic arms of the curve.

The investigation of solid waste around Port Harcourt, Rivers State Nigeria was carried out to acquire information on the condition of the soil and the types of waste as well as the nature of leachates produced within the environment. It aims at predicting hydrogeologic site conditions and contaminating transport potential. Samples were collected at three locations using hand auger at depths of 1 m, 2 m and 3 m and laboratory analyses conducted. Results of the soil analyses revealed medium grained sands with average permeability of 10-3mm3/s while the chemical analyses of leachates indicated high concentration of the waste derivates which have been degraded. Among the parameters measured, the average values of pH, 8.8; conductivities 1750 mS/cm and total dissolved solids (TDS)1150 mg/L of the boreholes (BHI, BH2 and BH3) are above the world health organization (WHO) standards of 8.0, 1500 mS/cm and 450 mg/L respectively. The government of Rivers State and Port Harcourt municipality should design, construct and control dumpsites and their associated leachates.