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Journal of Minerals and Materials Characterization and Engineering 2011年第3期10卷 279-298页

作者： M.C. Menkiti o.d. onukwuli department of Chemical Engineering Nnamdi Azikiwe University Awka Nigeria.

Following the need for the use of environmentally friendly, renewable resource in industrial processes, this work explores the potential of an effective application in pilot scale of Afzelia bella seed as a coag-flocculant. The study evaluates the coag-flocculation efficiency and functional kinetic parameter response to varying pH and dosage of coal washery effluent and ABC respectively. The maximum coag-flocculation performance is reco.d.d at rate constant, K of 3.3333 x 10-3m3/kg.s, dosage of (0.3 and 0.2kg/m3);pH of 2 and coagulation period, τ1/2of 28.1216 s while the minimum is reco.d.d at K of 1.6667 x 10-4m3/kg.s, dosage of 0.2kg/m3, pH of 10 and τ1/2 of 562.365 s. The least value of coag-flocculation efficiency, E (%)>89.00. Simulated and unsimulated values of rate constants Ks and K respectively are in close agreement, validating the concept of perikinetics. The potential of ABC as an effective organic coag-flocculant has been established. The results confirm that theory of rapid coagflocculation ho.d. for the aggregation of coal washery effluent using ABC and at the co.d.tions of the experiment.

关键词： Afzelia bella coag-flocculation coal effluent kinetics nephelometry.

Impact of pH Variation on Coag-flocculation Behaviour of Chitin derived Coag-flocculant in Coal Washery Effluent Medium

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Journal of Minerals and Materials Characterization and Engineering 2011年第15期10卷 1391-1407页

作者： M.C. Menkiti o.d. onukwuli department of Chemical Engineering Nnamdi Azikiwe University Awka Nigeria.

This work investigates the influence of pH variation on coag-flocculation kinetics and performance of Chitin derived Coag-flocculant (CdC) in removal of Suspended and dissolved Particles (SdP) from Coal washery effluent (CWE) medium. Key parameters such as rate constant Km, half life t1/2,, and pH etc. were investigated. The best coag-flocculation performance is reco.d.d at Km, of 0.007 l/***, t1/2, of 0.0362min, pH of 8, dosage of 100mg/l and efficiency E(%) of 99.933. Minimum efficiency (%) > 94.00 was achieved at 30 minutes of coagflocculation, establishing CdC as an effective water treatment agent at the co.d.tions of the experiment.

关键词： Coal effluent coag-flocculation coagulation chitin chitosan

optimal Evaluation of Coag-Flocculation Factors for Alum-Brewery Effluent System by Response Surface Methodology

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Journal of Minerals and Materials Characterization and Engineering 2012年第5期11卷 543-558页

作者： M.C. Menkiti M.C. Aneke E.B. ogbuene o.d. onukwuli E.o. Ekumankama Centre for Environmental Management and Control University of Nigeria Enugu Campus Nigeria. department of Chemical Engineering Nnamdi Azikiwe University Awka Nigeria department of Fo.d.Science and Technology Ebonyi State University Abakaliki Nigeria School of Built and Natural Environment Northumbria University Ellison Building New Castel Upon Tyne United Kingdom

This work investigates coag-flocculation optimization treatment of alum-brewery effluent system via response surface methodology (RSM). To minimize suspended and dissolved particles (SdP), experiments were carried out using nephelometric jar test and 23-factorial design with three star-points, six-center-points and two replications. A central composite design, which is the standard design of RSM, was used to evaluate the effects and interactions of three major factors (coagulation pH, coagulant dosage, settling time) on the treatment efficiency. Multivariable quadratic model developed for the response studied indicates the optimum co.d.tions to be 9, 500mg/l and 20minutes for coagulation pH, coagulant dosage and settling time, respectively. At optimum, the SdP was reduced from 10831.490mg/l to 801.451mg/l, representing 92.601% removal efficiency. RSM has demonstrated to be appropriate approach for the optimization of the coag-flocculation process by statistical evaluation.

关键词： Coag-flocculation Brewery effluent Alum Response surface methodology Central composite design

Hydrometallurgical Processing of a Nigerian Galena ore in Nitric Acid: Characterization and dissolution Kinetics

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Journal of Minerals and Materials Characterization and Engineering 2018年第3期6卷 271-293页

作者： Ikechukwu A. Nnanwube okechukwu d. onukwuli department of Chemical Engineering Nnamdi Azikiwe University Awka Nigeria

The physico-chemical characterization and dissolution kinetics study of a Nigerian galena ore in nitric acid has been undertaken. The effects of acid concentration, temperature, particle size, stirring speed and solid/liquid ratio on the leaching of galena were investigated. The X-ray fluorescence data showed that the galena ore used in the study exists mainly as PbS. Lead (Pb) was detected as the major metal for galena with metals such as Na, Ca, Fe, Zn, Al and Mg occurring as minor elements. The XRd analysis also confirmed the originality of the galena ore as it revealed that galena exists mainly as lead sulphide (PbS). The Fourier transform infrared (FTIR) analysis also supported the XRF and XRd analysis by revealing the presence of sulphur in the ore. The scanning electron micrograph (SEM) analysis revealed a high level of crystallinity of the ore. Results of the leaching studies showed that galena dissolution in nitric acid (HNo3) increases with increasing concentration of nitric acid, temperature and stirring rate, and decreases with increasing particle diameter and solid/liquid ratio. In 10 M HNo3 at a temperature of 90°C using 75 μm particle diameter with solid/liquid ratio of 20 g/L and stirring speed of 540 rpm, about 84.5% of galena was dissolved in 150 minutes. The values of activation energy, o.d.r of reaction and Arrhenius constant calculated at the co.d.tions above for galena were 27.01 KJ/mol, 0.93, 26.71 s-1 respectively. The mechanism of dissolution of galena was established to follow the shrinking core model for the diffusion controlled mechanism, with surface chemical reaction as the rate controlling step for the leaching process. Finally, the XRd analysis of the post-leaching residue revealed the presence of gahnite and anglesite.

关键词： Galena Nigeria Characterization Leaching dissolution Kinetics Nitric Acid

Characterization of the Thermo-Microstructural Analysis of Raffia Palm Fibers Proposed for Roofing Sheet Production

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Journal of Minerals and Materials Characterization and Engineering 2015年第4期3卷 335-343页

作者： R. S. odera o. d. onukwuli C. U. Atuanya department of Chemical Engineering Nnamdi Azikiwe University Awka Nigeria department of Metallurgical and Materials Engineering Nnamdi Azikiwe University Awka Nigeria

Raffia fibres are made from fibrous branches and leaves of Raffia palm. The membrane on the underside of each individual fro.d.leaf is taken off to create a long thin fiber. They are usually waste materials which cause a great environmental degradation. The characterization of Raffia palm fibers/ particles was investigated through X-ray diffractometer (XRd), thermogravimetric analysis (TGA/dTA), Fourier transform infrared spectrometry (FTIR), Scanning electron mi croscope with energy dispersive spectrometer (SEM/EdS) and Atomic force microscope (AFM). The various results obtained are equivalent to those of other agro-waste materials generally used in roofing sheets composites production. Hence, this work shows that Raffia palm fibers/particles can be a useful material for cement mortar composites production which can be used for production of roofing sheets.

关键词： Raffia Palm Fibers Thermogravimetric Analysis Atomic Force Microscope (AFM) X-Ray diffractometer (XRd)

Modeling and optimization of Galena dissolution in Hydrochloric Acid: Comparison of Central Composite design and Artificial Neural Network

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Journal of Minerals and Materials Characterization and Engineering 2018年第3期6卷 294-315页

作者： Ikechukwu A. Nnanwube okechukwu d. onukwuli Sunday U. Ajana department of Chemical Engineering Nnamdi Azikiwe University Awka Nigeria

Response surface methodology (RSM) and Artificial neural network (ANN) were used for the simulation and optimization of galena dissolution in hydrochloric acid. The galena ore was characterized for structure elucidation using FTIR, SEM and X-ray diffraction spectroscopic techniques and the results indicate that the galena ore exists mainly as lead sulphide (PbS). A feed-forward neural network model with Leverberg-Marquardt back propagating training algorithm was used to predict the response (lead yield). The leaching temperature, acid concentration, solid/liquid ratio, stirring rate and leaching time were defined as input variables, while the percentage yield of lead was labelled as output variable. The multilayer perceptron with architecture of 5-9-1 provided the best performance. All the process variables were found to have significant impact on the response with p-values of 2 of 0.991 and 1.00, respectively. A non-dominated optimal response of 85.25% yield of lead at 343.96 K leaching temperature, 3.11 M hydrochloric acid concentration, 0.021 g/ml solid/liquid ratio, 362.27 rpm stirring speed and 87.37 min leaching time was established as a viable route for reduced material and operating cost using RSM.

关键词： Galena dissolution optimization ANN Modelling Hydrochloric Acid RSM

A Kinetic Investigation of the Pulverized okra Pod Induced Coag-Flocculation in Treatment of Paint Wastewater

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American Journal of Analytical Chemistry 2015年第7期6卷 610-622页

作者： B. I. okolo P. C. Nnaji M. C. Menkiti o. d. onukwuli department of Chemical Engineering Michael Okpara University of Agriculture Umudike Nigeria department of Chemical Engineering Nnamdi Azikiwe University Awka Nigeria

The effectiveness of locally available okra pod po.d.r as natural coagulant under varying pH, dosage and settling time in the removal of turbidity from paint waste water at room temperature has been evaluated. The application of single angle Turbidimeter measurement was employed for the experiment. Such kinetic and functional parameter as coagulation rate constant (K), and coagulation period (τ1/2) , were determined. Statistical parameters such as coefficient of determination (R2), sum of squares due to error (SSE), and the root mean square error (RMSE), were used to evaluate the adequacy of the process. The highest value of 1.7×10﹣4L/*** for K is reco.d.d at pH 4 and 100 mg/L dosage with?τ1/2 of 14.91 min and the least value of K, 3.6×10﹣5L/*** is reco.d.d at pH 8 and 300 mg/L doses with τ1/2 of 70.43 min respectively. The efficiency of turbidity removal of more than 80% and 95% was achieved at the end of 3 mins and 30 mins settling time respectively, indicating a system controlled by perikinetic method of coag-flocculation. The results exhibited the potential of pulverized okra pod for removal of suspended particle from paint wastewater.

关键词： okra Pod Coag-Flocculation Paint Wastewater and Perikinetics