U.M. Eduok

Effect of polyvinylpyrrolidone – polyethylene glycol blends on the corrosion inhibition of aluminium in HCl solution

Purpose – The purpose of this paper is to investigate the effect of polyethylene glycol (PEG), polyvinylpyrrolidone (PVP) and blended formulations on the corrosion inhibition of aluminium in HCl solutions at 30-60°C and to study the mechanism of action. Design/methodology/approach – The inhibitive effect of the homopolymers and polymer blend was assessed using weight loss and hydrogen evolution methods at 30 and 60°C. The morphology of the corroding aluminium surface without and with the additives was visualized using atomic force microscopy. The trend of inhibition efficiency with temperature was used to propose the mechanism of inhibition and type of adsorption. Findings – Results obtained show that inhibition efficiency (η%) increases with increase in concentration of the polymers but decreases with increase in temperature. The inhibition efficiency of the homopolymers and their blends decreased with rise in temperature. Inhibition efficiency was found to be synergistically enhanced on blending the two...

Humic Acid from Livestock Dung: Ecofriendly Corrosion Inhibitor for 3SR Aluminum Alloy in Alkaline Medium

Humic acids (HAs) extracted from cow, goat, and poultry dung were studied. Extraction was performed by treating the source materials with acid hydrolysis using hydrochloric acid (HCl) before alkaline extraction with sodium hydroxide (NaOH). Yields of 3.33, 2.67, and 1.28% dry weight were obtained from cow, goat, and poultry dung respectively. The extracted humic acids were characterized using Fourier transform-infrared (FT-IR) and ultraviolet-visible (UV-vis) spectroscopy techniques. The results obtained were in good agreement with commercial HA (Sigma-Aldrich). The humic acid extracted from cow dung was used to evaluate its corrosion inhibition potential for alkaline-induced corrosion of 3SR aluminum alloy using weight loss and electrochemical (potentiodynamic polarization) techniques at 30°–60°C. Results obtained show that the humic acid functions as an excellent corrosion inhibitor for aluminum alloy in 0.1 M NaOH solution. Corrosion inhibition efficiency increased with increase in humic acid concentration but decreased with rise in temperature. Results from potentiodynamic polarization measurements show that the HA behaved mostly as a mixed-type inhibitor. Adsorption of the humic acid was found to obey the Langmuir adsorption isotherm at all concentrations and temperatures studied. The mechanism of physical adsorption has been proposed based on the trend of inhibition efficiency with temperature. The proposed mechanism was also corroborated by kinetic and thermodynamic parameters obtained.

The role of pH in metal ion removal using coir dust and its modified extract resins

The role of pH on metal ion adsorption by unmodified coir dust and its modified extract forms (namely carboxylated and sulphonated coir extract resins) was studied in a batch system. The zero point charge pH (pH pzc) of the adsorbents was determined and the results demonstrated that the amount of metal ions adsorbed by the adsorbents was dependent on pH(pzc). The adsorption of these metal ions by the adsorbent increased with increasing pH. The unmodified coir dust, being a lignocellulosic material, removed more metal ions than the modified coir extract resins derived from a tannin-polyhydroxy compound. Hydroxyl, carboxylic and sulphonic functional groups are responsible for the metal ion binding in these adsorbents, as revealed by infra-red spectroscopic analysis. Coir dust, carboxylated coir extract (CTR) and sulphonated coir extract resin (STR) are effective adsorbents for removal of metal ions from aqueous solution and industrial effluents/wastewater.

Trace Elements in Ground and Packaged Water in Akwa Ibom State, Nigeria

ABSTRACT About 20 trace elements were measured in 165 ground water samples, 8 commercial brands of bottled and sachet water in Akwa Ibom State, Nigeria to ascertain their quality and suitability for drinking purposes. A comparison of the elemental concentrations with World Health Organization (WHO) guidelines and Nigerian Standard for Drinking Water Quality (NSDWQ) showed that with the exception of Al, Cd, Pb, and Fe in some of the ground and packaged water samples, the levels of all the other elements investigated were below the maximum allowable limits. Hierarchical cluster analysis grouped 16 sampling local government councils into four clusters of similar water quality characteristics. Based on the obtained information, it is possible to design a future, optimal sampling strategy for monitoring programs which could reduce the number of sampling stations and associated costs.