In this work, multiwall carbon nanotubes (MWCNTs) developed from cobalt-ferrite catalyst on activated carbon (from castor seed), was used as an adsorbent for the removal of cadmium and hexavalent chromium ions. The effectiveness of the adsorbent for the uptake of Cd(II) and Cr(VI)ions from aqueous solution was investigated in a process batch adsorption study. The developed activated carbon and MWCNTs were characterized by Brunauer-Emmett-Teller (BET) surface area analysis, Fourier Infrared Spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) for the determination of surface area, functional group, and surface morphology, respectively. The BET surface area of activated carbon and developed adsorbent from Co-Fe/AC was 230.24 and 372.42 m 2 /g, respectively. The operational parameters evaluated on the adsorption efficiency were solution pH, temperature, adsorbent dosage initial metal ions concentration, and contact time. The adsorption of Cd(II) and Cr(VI) were found to have attained equilibrium positions in 60 min for the concentration range tested, respectively. The four linearized adsorption isotherm models; Langmuir, Freundlich, Temkin and Dubinin Radushkevich (D-R) tested, when compared, revealed that Langmuir isotherm fitted well to the experimental data judging from the higher correlation coefficient values (R 2 ) and lower values of the error functions (chi-square (χ 2 ), the sum of square error (ERRSQ/SSE) and the sum of absolute error (EABS))with monolayer adsorption capacities of 404.858 and 243.902 mg/g for Cd(II) and Cr(VI) ions, respectively. Adsorption kinetic models investigated by pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion showed the conformity of pseudo-second-order model to the process adsorption as informed by the higher values R 2 and Adj, R 2 , maximum log-likelihood and smaller ERRSQ/SSE, χ 2 , Akaike information criterion (AIC), Bayesian information criterion (BIC), and Hannan-Quinn information criterion (HQIC). The intraparticle diffusion model plots indicated that intraparticle diffusion was not the only rate-limiting step. Thermodynamic adsorption parameters (ΔH o and ΔG o , ΔS o ) showed that the adsorption of Cd (II) and Cr (VI) ions was spontaneous, endothermic, and increased in randomness between the adsorbate-adsorbent. The mean adsorption energy (E), the heat of adsorption (ΔH o ), and activation energy (E a ) values, revealed the adsorption mechanism of Cd(II) and Cr(VI) onto MWCNTs as a combination of chemical and physical adsorption but dominated more by chemical adsorption. IntroductionWater is particularly important to the existence of living organisms in the world. However, human activities which include population growth, industrialization increase, and urbanization have caused rapid contamination, compromising the availability of potable water [1]. The release of harmful substances like heavy metals, due to human actions, has posed environmental problems, affecting human health [2,3]. Heavy metals like chromium and cadmium when exceed...

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The inhibiting effects of Chicken Nails Extract (CNE) on Mild Steel corrosion in 2M H2SO4 were investigated in this study. The effect of the concentration of inhibitor (0.5–1.5 g/l), time (5–8 h) and temperature (40-70oc) on Inhibition efficiency were investigated using Response Surface Methodology. The Physiochemical analysis and proximate analysis of the CNE were investigated; the result showed that organic constituents were present which made the Chicken nails extract a good inhibitor. The rate of corrosion increases as time and temperature increase while the Inhibition efficiency was discovered to increase as the inhibitor concentration increases. The optimum conditions obtained were temperature 63.63 °C, time 5 h and inhibitor concentration of 0.1 g/l. The optimum Inhibition Efficiency at these optimum conditions was predicted to be 74.04%. The micrographs result of Scanning Electron Micrographs analysis showed that in the presence of the inhibitor, there was a passive layer of a film formed on the surface. This study revealed that Chicken Nails Extract is a potentially good green inhibitor for Mild steel corrosion in 2M H2SO4.

This research was carried out to optimize biodiesel production from castor oil using 24 full factorial central composite design (CCD). Transesterification method was used for the biodiesel production from castor using KOH & NaOH were used as catalysts. Physico-chemical properties including density, kinematic viscosity, acid value, saponification value, iodine value and pour point. The results were determined both on the castor oil and biodiesel produced. The predicted optimum conditions for the production of castor oil biodiesel are; reaction time of 60 minutes at the temperature of 60°C, catalyst concentration of 3.5 g and a methanol/oil molar ratio of 5:1. The biodiesel yield was 99.76% and the result of the measured properties of biodiesel was compared with the international standards of EN14214 and ASTM D6751. The weight composition of the fatty acid and methyl ester were both determined by the Gas Chromatography (GCMS)

Due to the subtle occurrence of environmental polycyclic aromatic hydrocarbon (PAHs) pollution from incinerators, it is seldom considered a significant source of PAH pollution. However, considering the recent build-up of toxics in urban air, this may be a serious concern around the incinerator vicinity due to the potential consequences of PAHs on human health. Hence, this study determined 11 alkyl-naphthalene contributions from a hospital waste incinerator (HWI_0) into ambient air receptor points (HWI_1 to HWI_5) for a 1-year period: June 2014-May 2015. The HWI_0 and ambient gases were sampled using filter-sorbent sampling system and polyurethane foam (PUF) passive samplers, respectively, and all alkyl-naphthalenes were determined using GC-MS. Results showed that the source concentrations were in the range of 0-14.0 ng/m and generally higher than the receptor points. The receptor point concentration trends were mainly HWI_1 > HWI_2 ≥ HWI_3 ≥ HWI_5 ≥ HWI_4. Multivariate receptor model analysis suggested high correlations between source and the receptor points though there might be some significant contributions from other emission sources. The average monthly concentrations (∑alkyl-naphthalene) at HWI_0 and the receptors HWI_1, HWI_2, HWI_3, HWI_4 and HWI_5 were 67.4 ± 24.3, 57.9 ± 20.1, 42.8 ± 16.9, 39.7 ± 12.2, 36.5 ± 22.2 and 37.8 ± 15.4 ng/m, respectively. Though these concentrations were lower than the estimated minimal risk level (MRL) for chronic inhalation exposure to naphthalene and its derivatives 0.003 mg/m, continuous exposure to these pollutants might result in chronic effects. Finally, this study may be used to evaluate the environmental contribution of alkyl-naphthalenes from typical medical waste incinerator in Nigeria.

The overdependence on crude oil has produced susceptivity to every part of the Nigerian Gross Domestic Growth (GDP) and there was the need to examine the effect of crude oil on the economy of Nigeria. This study, therefore, investigates the long-run effect between oil revenue, oil price volatility, and economic growth in Nigeria. The data on oil revenue, non-oil revenue, oil price volatility, and per-capita income from the year 2006 – to 2020 extracted from the Central Bank of Nigeria (CBN) Statistical Bulletin was applied in this research work. The research applied Descriptive Statistics, Augmented Dickey-Fuller Unit Root test, Johansen cointegration, and Autoregressive Distributed Lag (ARDL) co-integration statistical method to examine the long-run effects of crude oil production on Nigeria’s economy. It was discovered from our result that; oil revenue plays a remarkable role in Nigeria‘s economy by its advancement of the country’s GDP. Furthermore, Nigeria has regulated oil revenue to accomplish economic growth in numerous ways. The study recommended that the Nigerian Government should diversify its export supply through downstream production and encouragement of more private sector participation.

The effect of Katemfe Seed Extract as inhibitor for Galvanized steel in 1M HCl acidic media was investigated in this study. The combination of the concentration of inhibitor (0.2-1.0 g lG 1 ), time (1-5 h) and temperature (30 ) on corrosion rate was investigated using optimization. The optimum conditions obtained were temperature 54.55; time 2.28 h and inhibitor concentration of 0.20 g LG 1 . The obtained optimal value of 85.9% predicted agreed closely with the 86.5% obtained from the experiment. The micrographs result of Scanning Electron Micrographs analysis showed that the passive layer of film was formed on the surface. This study showed that Katemfe seed extract is a good inhibitor for Galvanized steel in 0.5 M HCl.

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