Now showing 1 - 5 of 13
- ItemOpen AccessRemoval of Cadmium (II) and Nickel (II) Ions from Aqueous Solution using Corncob Waste(University of Lagos Press, Akoka, 2017) Onwordi, C.T; Okwuolise, C.H; Osifeko, O.L; Oguntade, B.K; Wusu, A.D; Petrik, L.FThe rapid spate of development of many industries has led to wastes containing heavy metals being directly or indirectly discharged into the environment. This study employed the use of corncob an agricultural waste for adsorption of cadmium (II), cobalt (II), and nickel (II) in batch mode at room temperature. The residual metal was determined with flame atomic absorption spectrophotometer. The study investigated the influences of adsorbent dosage, solution pH, contact time, and initial metal concentration on the removal of metal ions. The Langmuir and Freundlich isotherm models were used to fit the equilibrium adsorption data. The reaction kinetics of the cadmium (II), cobalt (II) and nickel (II) removal from the aqueous solution were identified and correlated to the pseudo first and second order kinetic models. The results showed an increase in adsorption by metal ions studied with an increase in adsorbent dosage. Metal uptake showed a pH-dependent profile with optimum at pH values 4.0 for Cd (II) as well as Ni (II), and 8.0 for Co (II) ions. The Freundlich adsorption isotherms model fitted the experimental data best with the regression coefficient ranging between 0.837 and 0.989 for the metal ions. A kinetic study of the adsorption process showed that adsorption of cadmium (II), cobalt (II), and nickel (II) on corncob was observed to follow closely to the pseudo-second–order. It was concluded that corncob exhibited rapid adsorption capabilities and high efficiency in removal of cadmium (II), cobalt (II) and nickel (II) ions from aqueous solution.
- ItemOpen AccessSpectrophotometric and High Performance Liquid Chromatograhic Determination of Sodium Benzoate and Potassium Sorbate in some Soft Drinks(University of Lagos Press, Akoka, 2017) Ogunleye, D.T; Oyeyiola, A.O; Onwordi, C.T; Falana, T.G; Abolade, O.MSodium benzoate and potassium sorbate are preservatives commonly used in drinks and their concentration is of importance due to their health implications. This research is aimed at determining the concentration of sodium benzoate and potassium sorbate in some drinks sold in Lagos, Nigeria using high performance liquid chromatography (HPLC) and UV-visible spectrometry. Thirty samples were collected from different super markets in Lagos State and the pH, as well as the concentration of sodium benzoate and potassium sorbate were determined. A significant difference was observed between the HPLC and the UV methods at 95% confidence limit. The concentration of sodium benzoate in the different drinks analysed, ranged from ND to 1040 mg/L and that of potassium sorbate from ND to 499 mg/L. It was observed that about 40 % of the drinks were above the limit of 150 mg/L for benzoate, while 43 % were found to contain concentrations of sorbate above the permissible limits of 250 and/or 300mg/L. The acceptable daily intake (ADI) per kg of body weight of some consumers was exceeded, and this could expose the consumers to the adverse effect of continuous consumption of these drinks. Keywords: Drinks, HPLC, potassium sorbate, sodium benzoate,
- ItemOpen AccessReducing the Observable States Space of Hidden Markov Model for Distributed Denial of Service Attack Prediction using Kullback-liebler Divergence(University of Lagos Press, Akoka, 2017) Afolorunso, A.A; Adewole, A.P; Abass, O; Longe, H.ODistributed Denial of Service (DDoS) attack floods the network with loads of unwanted packets and requests that weigh down the system resources such as memory and processors. Hidden Markov model (HMM) is one of the models that can be used to predict and detect such attacks. A problem to be solved was determining the observable states and subsequently, the model parameters since the performance of the model depends on the accurate selection of these parameters. In this work, the concept of entropy was used to determine the observable states, which characterise the HMM. In order to improve computational efficiency of the algorithm for estimating the parameters of the model, Kullback-Liebler Divergence (KLD) method was employed for reducing and selecting appropriate observable states to achieve a good prediction model. The experimental results justified the suitability of KLD in reducing the entropy-based observable states of HMM for predicting DDoS attack.
- ItemOpen AccessModelling and Simulation of Ecap and P-Cap Techniques of Grain Inducement in Mild Steel(University of Lagos Press, Akoka, 2017) Esezobor, D.E; Onovo, H.O; Ojo, A.O; Bodude, M.ADue to major obstacles associated with the powder consolidation methods of producing bulk nano materials such as high cost, contamination and porosity, severe plastic deformation (SPD) technology, specifically the equal channels angular pressing (ECAP) technique is used with modifications to numerically simulate the much needed grain refinement in steel. Attempts are made in this study to investigate influence of processing parameters such as deformation routes, temperature, load and number of processing passes on the degree of strain inducement in steel. This study however, aimed at developing fourth generation metals of exceptional strength, formability and toughness. The materials used in this work include conventional mild steel and ABAQUS commercial software. Simulation and modeling of the proposed deformation and ECAP techniques were done using finite element based-method (FEM). The results obtained indicate that the desired performance index of the metal is dependent on the state of the metal prior to ECAP and the degree of deformation.
- ItemOpen AccessMonitoring of Concentration of Air Pollutants from Vehicular Emission along Major Highways and Bypass within Kosofe Local Government Area, Lagos State(University of Lagos Press, Akoka, 2017) Oluseyi, T.O; Akinyemi, M.IVehicular emissions are considered a major source of urban air pollution. Pollutants from these emissions whether as individual compounds or by synergistic interaction impacts negatively on public health, vegetation and climate. In this paper, we evaluate baseline concentration of carbon monoxide (CO), oxides of nitrogen (NOx), sulphur dioxide (SO2) and particulate matter (PM) from vehicular emissions during peak and off-peak periods along 3 major highways within Kosofe and Ikeja Local Government Areas (LGA) of Lagos State. Air quality monitoring/gas detection equipment were used to measure (in-situ method) ambient levels of the pollutant in nine locations within the selected area. The results revealed that the Federal Ministry of Environment’s Ambient Air Quality Standard limit was exceeded by most of the gases in majority of the locations. Statistical analysis revealed significant variations in the concentration of these gases across locations. Heavy vehicular traffic, poor traffic management and frequent traffic congestion were observed as factors responsible for the high pollutant concentration.