Estimation of longitudinal dispersion co-efficient: A review

Accurate determination of longitudinal dispersion coefficient in rivers or streams is necessary for pollution control and management. This can be achieved through tracer studies and has proven to be a reliable method for measuring pollution spread. However, tracer studies practise which is expensive, time gulping and requiring large labour input have been substituted with empirical approaches thereby reducing the applicability of the dispersion coefficient models generated. This study reviews the various models derived as well as methods associated in the collection of tracer concentration data (measurement) existing in the literature. A sustainable approach to this study was identified and research needs were also listed

Anticorrosion Performance of Solanum Aethiopicum on Steel-Reinforcement in Concrete Immersed in Industrial/Microbial Simulating-Environment

This paper investigates anticorrosion performance of Solanum aethiopicum leaf-extract on steel-reinforcement in concrete immersed in 0.5 M H2SO4, simulating industrial/microbial environment. For this, corrosion rate by linear polarisation resistance and corrosion potential as per ASTM C876-91 R99 were monitored from steel-reinforced concrete slabs admixed with different Solanum aethiopicum leaf-extract concentrations and immersed in the acidic test-environment. Obtained test-data were subjected to statistical probability distributions for which compatibilities were tested using Kolmogorov-Smirnov goodness-of-fit statistics, as per ASTM G16-95 R04. These identified all datasets of corrosion test-data, from the steel-reinforced concrete samples, as coming from the Weibull probability distribution. Analysed results showed that Solanum aethiopicum leaf-extract reduced rebar corrosion condition from “high” to “low” corrosion risks of ASTM C876-91 R99. Also, the corrosion rate analyses identified 0.25% Solanum aethiopicum leaf-extract with optimal inhibition efficiency performance, η = 93.99%, while the other concentrations also exhibited good inhibition of steel-reinforcement corrosion in the test-environment

Cassia fistula Leaf-Extract Effect on Corrosion-Inhibition of Stainless-Steel in 0.5 M HCl

This paper investigates Cassia fistula leaf-extract effects on the inhibition of stainless-steel corrosion in 0.5 M HCl. Measurements of corrosion rate were obtained through linear sweep voltammetry (LSV) technique, at the ambient temperature of 28 °C from stainless-steel specimens immersed in the acidic medium, containing different Cassia fistula leaf-extract concentrations. Results showed that inhibition effectiveness on stainless-steel corrosion increases with increasing concentration of the leaf-extract. The 10 g/L Cassia fistula leaf-extract, the highest concentration of the leaf-extract employed in the study, exhibited optimal inhibition efficiency η = 88.46% on the corrosion of the stainless-steel metal. Adsorption isotherm modelling shows that the experimental data followed the Flory-Huggins isotherm with excellent model efficiency, r2 = 90.27%, and the Langmuir model with very good model efficiency, r2 = 78.83%. Other isotherm parameters indicate favourable adsorption and suggest physisorption as the prevalent mechanism of corrosion protection by the leaf-extract on stainless-steel in the acidic chloride environment

C3H7NO2S effect on concrete steel-rebar corrosion in 0.5 M H2SO4 simulating industrial/microbial environment

This paper investigates C3H7NO2S (Cysteine) effect on the inhibition of reinforcing steel corrosion in concrete immersed in 0.5 M H2SO4, for simulating industrial/microbial environment. Different C3H7NO2S concentrations were admixed, in duplicates, in steel-reinforced concrete samples that were partially immersed in the acidic sulphate environment. Electrochemical monitoring techniques of open circuit potential, as per ASTM C876-91 R99, and corrosion rate, by linear polarization resistance, were then employed for studying anticorrosion effect in steel-reinforced concrete samples by the organic hydrocarbon admixture. Analyses of electrochemical test-data followed ASTM G16-95 R04 prescriptions including probability distribution modeling with significant testing by Kolmogorov-Smirnov and student's t-tests statistics. Results established that all datasets of corrosion potential distributed like the Normal, the Gumbel and the Weibull distributions but that only the Weibull model described all the corrosion rate datasets in the study, as per the Kolmogorov-Smirnov test-statistics. Results of the student's t-test showed that differences of corrosion test-data between duplicated samples with the same C3H7NO2S concentrations were not statistically significant. These results indicated that 0.06878 M C3H7NO2S exhibited optimal inhibition efficiency η = 90.52±1.29% on reinforcing steel corrosion in the concrete samples immersed in 0.5 M H2SO4, simulating industrial/microbial service-environment

Investigating Prospects of Phyllanthus Muellerianus as Eco-friendly/Sustainable Material for Reducing Concrete Steel-reinforcement Corrosion in Industrial/Microbial Environment

Characterization and experimental modelling were employed for investigating prospects of Phyllanthus muellerianus as eco-friendly/sustainable material for reducing concrete steel-reinforcement corrosion in industrial/microbial environment. Atomic Absorption Spectroscopy/Fourier Transform Infra Red Spectroscopy of the inorganic and organic constituent of the leaf, as well as total-corrosion effects of the leaf-extract admixture in steel-reinforced concrete were requisitely analyzed and interpreted. Results showed that Phyllanthus muellerianus is constituted of non-toxic level of inorganic/heavy metals, useful phytochemical constituents and essential heteroatoms that makes it potent with excellent reduction effects on the total-corrosion model of steel-reinforcement in concrete immersed in the industrial/microbial simulating-environment studied. © 2015 The Authors. Published by Elsevier Ltd