Studies on castor seed shell as a sorbent in basic dye contaminated wastewater remediation

The potentialities of castor seed shell (CSS), a waste agricultural by-product, in the remediation of water, contaminated with Methylene Blue (MB), a basic dye, were investigated in the present study. The CSS was ground and washed, thoroughly, to remove any water extractable constituents. The dried CSS was reground, sieved and used in series of agitated batch adsorption experiments. The experiments were conducted to assess the effect of two process variables i.e. initial MB concentration and CSS dosage on the sorption process. The equilibrium sorption isotherm was studied using the two widely used isotherm models (i.e. Freundlich and Langmuir isotherm models). The results from the isotherm studies showed that the process of sorption of MB occurred on a heterogeneous surface of the CSS. The sorption capacity of the CSS, as obtained from the Langmuir plot was 158 mg/g. The mass transfer property of the sorption process was studied using Lagergren pseudo-first-order and chemisorptions pseudo-secondorder kinetic models. The sorption process obeyed the pseudo-second-order kinetic model more than the pseudo-first order; hence the mechanism of the sorption process was analysed further using this kinetic model. The application of the intraparticle diffusion model to determine the rate limiting step showed that intraparticle diffusion is not the singular rate limiting step in the sorption of MB onto CSS. The role of chemisorptions in the mechanism of sorption was established by an empirical relationship between the pseudo-second-order rate constant, K, and the initial MB concentration. The results of this relationship showed that pseudo-second-order chemisorptions are important in the sorption process.     

A spectroscopic study of vanadium in mushroom

Nine different species of mushroom were analysed spectrometrically for their vanadium contents. It was found that some edible species of mushroom, such as Agrocybe and Leutinus, contain vanadium in amounts either comparable with, or higher than, the amounts in some poisonous species. The result suggests that there is no correlation between the vanadium content of the mushroom species examined and their toxicity.     

Removal of Metal Ions From Wastewater With Roadside Tree Leaves

This paper reports on research related to the removal of heavy metal ions, such as lead, nickel, and zinc from wastewater by using tree leaves. Twelve different kinds of tree leaves were tested at room temperature. The experiments were carried out with 2 g of 40-50 mesh leaves in 200 mL synthetic wastewater containing about 50 mg/L metal ions. The initial pH of the synthetic wastewater was about 5. The experiments showed that the highest removal rates were 96% for lead (Pb ++ ), 61.7% for nickel (Ni ++ ), and 71.3% for zinc (Zn ++ ), compared with 93.9% for lead, 68.5% for nickel, and 72.1% for zinc achieved by activated carbon. Tree leaves appear to beagoodadsorbent for metal ion removal from wastewater.     

Background Radiation Measurement and the Assessment of Radiological Impacts due to Natural Radioactivity Around Itakpe Iron-Ore Mines

Mining activity and metal extraction processes have been identified as one of the major pathways through which natural radionuclides are accumulated in the terrestrial environment. Exposure to excessive radiation from natural radionuclides can cause deleterious health hazards to man. In this study therefore, the activity concentrations of primordial radionuclides (⁴⁰K, ²³⁸U and ²³²Th) were measured in rock, soil, tailings and water samples collected from abandoned iron ore mines in order to estimate the radiological impacts associated with the previous mining and metal extraction activities within the environment of abandoned Itakpe iron-ore mines. Gamma spectrometry utilizing a well calibrated NaI(Tl) detector was employed for the measurements. Results show that the average activity concentrations of ⁴⁰K, ²³⁸U and ²³²Th are 1084?±?581, 11.0?±?7.7 and 5.0?±?1.8 Bq kg^?1 respectively for rock samples and 415.6?±?197.5, 12.8?±?5.7 and 8.8?±?5.8 Bq kg^?1, respectively for soil samples. The activity concentrations of the three radionuclides are much lower in water samples compared to rocks and soil. Radiological hazard indices calculated from the activity concentrations show that the mining activities have little or no negative impacts on the environment as the radiological risk indices obtained are all lower than their permissible limits.     

Occurrence of metal and antibiotic resistant Escherichia coli harbouring zntA and copA genes in selected surface water in Ibadan,South-west Nigeria

ABSTRACT

Escherichia coli strains were isolated from surface water collected from three sampling points and cultured on CHROMAgar E. coli. The zinc and copper concentrations of the water samples were determined using Atomic Absorption Spectrophotometer. Colonies of Escherichia coli were subjected to increasing concentration (0.1–1.0 mM) of copper and zinc in the isolation medium. Isolates showing resistance to both metals at 1 mM were identified using conventional methods and by targeting the uidA gene, while PCR amplification of the copA and zntA genes was carried out using specific primers. The selected bacteria were subjected to 10 classes of antibiotics using the Kirby–Bauer disc diffusion technique. Five E. coli showing resistance to copper and zinc and possessing uidA gene were obtained. Of the five isolates, three possessed both zntA and copA genes, while zntA was absent in the remaining two. All the isolates peculiarly showed resistance to ampicillin and doxycycline, while three were multi-drug resistant (MDR).