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Proficiency of graphene oxide in adsorption of Zn(II) ions from aqueous solution
Get PDFA research article with figures and tablesThe efficient adsorption of metals on graphene oxide is often affected by the preparation method. Graphene oxide was prepared using a typical modified Hummers method for adsorptive removal of Zn2+ from aqueous solution. The experimental data were fitted into the Langmuir isotherm. The reaction was irreversible, but had a small energy of adsorption which was indicated by Freundlich isotherm model. Tempkin model and Dubinin Radushkevich revealed a physical adsorption process driven by a slow adsorptive process. The Pseudo 2nd order had the best correlation coefficient at 0.9958 while Langmuir was 0.9545. Elovich function indicated a non-spontaneous reaction, while the intra-particle diffusion was not the rate-determining step. The slow adsorption rate in pseudo 1st order correlated with the small adsorption energy shown by the Freundlich isotherm, and also correlated with the small boundary layer thickness shown by intra-particle diffusion. All adsorptive functions showed that some other competing mechanisms should exist. XRD showed an increased number of graphene layers, d-spacing and improved crystallite size. FTIR data showed the oxygen-containing groups on the graphene oxide surface.
The study showed that the prepared graphene oxide could efficiently adsorb Zn2+, and that the adsorption is affected by the method of synthesis
Level of heavy metals in soil samples from farmlands along highways in parts of Owerri, Nigeria
Get PDFThe article contains table and graphsThe research was designed to ascertain the concentrations of heavy metals (Cu, Pb, Zn, Ni, Cd) in soil samples from farmlands along highways in parts of Owerri. Soil samples were collected from cassava farms along three major roads with high traffic density and a rural road that served as control location, for possible heavy metals contamination due to vehicular emission. Standard laboratory procedures were adopted to determine the concentration of heavy metals using Atomic Absorption Spectrophotometer (AAS). Contamination factor (CF) and Pollution Load Index were mathematically calculated. The results revealed that the mean concentrations of metals in soil samples in mg/kg ranged from 3.00 – 6.31 for Cu; Pb, 0.09 – 4.00; Zn, 3.97 – 8.59; Ni, 0.001 – 0.96; and Cd, 0.31 – 0.79. These metals showed decrease in concentrations with increase in distance away from the highway. The values of contamination factor (CF) were low except for Cd and Pollution Load Index (PLI) for all soil studied showed no sign of pollution. There was no correlation between traffic density and concentration of heavy metal in soil except for Cd (Rs= 0.800). The overall results showed evidence of some heavy metal pollution on the soils with possible cumulative effect over time
Effectiveness of composites of corn cobs, coconut husks and breadfruit peels in purifying selected paint effluents
No full textThis research was conducted in collaboration with staff of this institution (FUTO)Due to the varying degrees of chemicals used in paint industries, the resulting effluent contains appreciable concentrations of toxic metals and inorganic anions which reduce the quality of the receiving streams, aquatic life and adverse effects on human health. This research aimed at determining the effectiveness of composites of Corn cob, Coconut Husk and bread fruit peels in purifying selected paint effluents through the assessment of their physicochemical properties before and after treatment using column adsorption technique. The experimental conditions observed were pH 4 and 8; adsorbent doses of 1g and 2g. Standard laboratory techniques involving the use of Atomic Adsorption Spectrophotometric method were adopted to determine the physicochemical properties of the effluent samples. The physicochemical results showed that the composites were effective in the removal of total solid, turbidity, colour, phosphate, nitrate, chloride, copper and cadmium while the values of COD, BOD, Lead and sulphate recorded noticeable increase on the treated effluent samples. The best experimental conditions according to the adsorption capacity were pH 4 and 1g adsorbent dose. The efficiency removal for heavy metal and inorganic anions in the effluent samples after treatment was in this order: Cl- ˂ Cu˂ NO3– ˂ PO4- ˂ Cd. Considering the values of R2 for the models fits to the experimental data, it can be concluded that all models can be used reasonably well to describe the behaviour of the adsorption of cadmium, copper, chloride, nitrate and phosphate, except for the partly negative values of Bohart – Adams and Thomas models. This research work shows that the use of corn cob, coconut husks and breadfruit peels as composite is more effective in reducing the concentrations of physicochemical properties of paint effluents
