Ambali Saka Abdulkareem

Synthesis and purification of bimetallic catalysed carbon nanotubes in a horizontal CVD reactor

Carbon nanotubes (CNTs) were synthesised by a conventional chemical vapour deposition (CVD) method using acetylene as carbon source and a bimetallic catalyst of Fe–Co supported on a CaCO3 support. The CNTs were characterised by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy (RS), energy dispersive X-ray spectroscopy (EDS) and thermogravimetric analysis (TGA). The TEM images show clustered CNTs and reveal the outer and inner diameters of these nanomaterials. The XRD analysis shows the characteristic broad peak of graphitised carbon; the RS indicates that these materials have a high degree of crystallinity while the TGA shows the high thermal stability of the materials. EDS analysis also indicates that the purification method employed was able to remove the impurities in the CNT samples.

Effect of Treatment Methods on Used Lubricating Oil for Recycling Purposes

The need to treat used lubricating oil for possible reuse has arisen due to concern for the environment, scarcity, price stability, and increasing dependence on this product for many industrial applications. Various methods, such as distillation/clay, acid/clay, acid, and activated charcoal/clay treatment methods, were employed in this study for the treatment of used Mobil and Total lubricating oil samples with the aim of improving their qualities for reuse. The characteristics of the fresh, used, and treated oil are tested for water content, specific gravity, kinematic viscosity, viscosity index, flash point, pour point, sulphur content, and concentrations of heavy metals (aluminum, iron, and lead). The results obtained showed that the usage of the lubricant oil affects the qualities of oil, for instance the sulphur of both brands of the oil samples was below the detectable limit, while the sulphur contents of the used oil are 0.80 and 0.69% for the used Mobil and Total oil samples, respectively. The results also revealed that treatments employed in this work were able to improve the characteristics of the used oil samples after treatment. The analyses of the results showed that the acid/clay method was the most effective method of treatment that brings the characteristics of the treated oil close to the fresh oil sample, while the distillation/clay and activated/charcoal methods were the best in terms of recovery of the oil after treatment. These two methods also recovered about 80% of the used lube oil samples compared to acid and acid/clay treatment methods, where the oil recovered was about 50% of the charge used oil sample.

Parametric effects on leaching behavior of nickel-copper matte in ammonia

Leaching, which is described as the extraction of soluble constituents from a solid by means of a solvent, is an important separation technique in the refining of precious metals from their matte. It is, therefore, important to investigate the extraction behavior of metals from the matte, which is the focus of this study. This study reports the influence of concentration of the solvent (ammonia), leaching temperature, leaching time, and pH on the recovery of nickel and copper from the matte. The elemental composition analysis of the matte indicated that it contains 23% copper, 37% nickel and 1.1% ferrous compound. The analysis also showed that the major mineral phases present in the matte were heazlewoodite (Ni3S2), chalcocite (Cu2S), djurleite (Cu1.9S), and nickel alloy. The leaching parameters studied were concentration of ammonia (1.5, 2.0, 2.5, and 3.0 M), leaching time (0–270 min, at 15 min sampling interval), leaching temperatures (50°C, 60°C, and 70°C), and pH (9.3–11.2). The results obtained revealed that the recovery of nickel and copper from the matte was greatly influenced by the concentration of ammonia, leaching time, leaching temperature, and pH. It was established from this study that the highest dissolution of nickel and copper was obtained at 3 M and 2 M ammonia concentration, respectively. The results also revealed that a decrease in the pH of the solution resulted in a decrease in both nickel and copper recovery, with maximum leaching time of 270 min. It was observed that less than 50% of both nickel and copper was leachable due to the presence of metal alloys. The analyses of the results also showed that as the leaching temperature increased from 50°C to 60°C, the amount of nickel and copper that was recovered from the matte significantly increased. However, there was reduction in the amount of nickel and copper recovered from the matte as the temperature was increased from 60°C to 70°C, due to loss of ammonia by evaporation. The shrinking core model was used to explain the behavior of the recovery of these metals at different temperatures, and both metals were found to be favored by diffusion controlled reaction.

The Production and Characterization of Ethyl Ester (Biodiesel) from Waste Vegetable Oil as Alternative to Petro Diesel

A process for the production of the ethyl ester from “used frying oil” for use as biodiesel fuel has been studied. The essential part of the process is the transesterification of the used frying oil with ethanol, in the presence of a catalyst (NaOH), to yield the ethyl ester as a product and glycerine as a by-product. Prior to the use of the waste vegetable oil as a feedstock in the production of biodiesel, the oil sample was treated with silica gel as an adsorbent and the results obtained indicate that the treatment method employed positively affects the free fatty acids and iodine value of the oil. Results obtained on the characterization of the biodiesel produced also shows that the viscosity, density, flash point, pour point, sulphur content, vapor pressure, and heat of combustion are 4.8 cP, 850 g/cm3, 145°C, −15°C, 0.02%, 64 kPa, and 42,600 kJ/kg, respectively. These values compared favorably with the petro diesel. The distillation properties of the produced biodiesel also compared favorably with that of the petro diesel with an initial boiling point of 141°C, final boiling point of 347°C, total recovery of 97.74%, with residue and loss of 1.23 and 1.03%, respectively.

Synthesis and Characterization of Lubricant Additives From Waste Plastic

This study attempted to synthesize and characterize engine oil additives from plastic waste, i.e., low density polyethylene, high density polyethylene, and poly propylene for the purpose of improving the viscosity index and pour point of engine oils. To do this, the starting polymers were reacted with maleic anhydride in a chain growth addition polymerization. The reactions took place in a muffle furnace at 230°C. The product poly (alkenymaleic anhydride) was then reacted with a glycerol at 140°C in a step growth addition polyesterification in the presence of xylene and nitrogen. The product formed, i.e., monoester acid, was then reacted with diethylene triamine in a step growth condensation polyamidation to produce the additive. The results obtained showed that the utilization of the additive produced from poly propylene as an additive on the base oils, i.e., SN150, SN500, BS 150 and commercially available oil (YT3513), gave the best results. The optimum blending concentration of 60 g/dl was achieved for the base oils except BS 150, which was 50 g/dl. Results also indicated that the optimum weight percentage of the blended additives was 3 wt%, while the optimum viscosity index was 162, 160, 159, and 186 corresponding to an increment of 80, 64.42, 36.76, and 36. 76% for SN150, SN500, BS150, and YT3513, respectively.

Predictive mathematical modeling and computer simulation of direct ethanol fuel cell.

ABSTRACT The challenges of finding a better substitute of energy as well as the shortcomings identified with direct ethanol fuel cell, includes high anode over potential and crossover necessitate the need to investigate the influence operating parameters on the performance of fuel through computer simulation. This study focus on the development of a predictive mathematical modeling for direct ethanol fuel cell for the purpose of investigating the influence pressure, temperature cathode, and reactants concentration on the performance, efficiency, and heat generated by the cell. Results obtained indicate that an increase in operating temperature led to a decrement in output voltage and cell efficiency, while the same condition of increasing the temperature positively favors the heat generated from the cell. Simulated results also show that cell performance is improved with an increase in concentration of the fuel (ethanol) and oxidant (oxygen). It can be inferred from this study that the cell performance of DEFC can be theoretically predicted with the developed model.

The Realities and Economic Benefit of the Utilization of Fuel Cells as an Alternative Source of Energy: A Review

The 21st century has seen a critical need for alternative cleaner sources of energy and fuel cells are one of the technologies that have been developed to address the need. This article reviews the realities of fuel cell technologies as an alternative source of energy. It gives insight into the past, present, and future status of fuel cells as a way of addressing the energy crisis. It can be inferred from this article that the fuel cell industry continues to be constrained in its ability to commercialize the technology by a circular logic whereby it cannot generate significant commercial sales due to relatively high costs of units. It is imperative that this cycle be broken by converted actions of the fuel cell industry, the user community, and the governments. In spite of the challenges of commercialization, it was noted that fuel cells have been successfully delivering power to several prototypes and specialized applications in recent decades. The power output of a fuel cell stack is easily scalable to provide the right amount of electricity for a laptop computer, a small car, a city bus, or even utility generation and power building not connected to a national grid.

Comparative Study of the Effect of Frothers on the Flotation of Nickel Sulphide Ore

Froth flotation process is an important process that involves solid-solid/solid-liquid separation of minerals from gangue. However, the performance of froth separation is affected by the types of frothers. The purpose of this study, therefore, was to determine the effect of different frothers in the flotation of low-grade nickel sulphide obtained in South Africa. Sodium isobutyl xanthate was used as a collector in this investigation. The mineralogy analysis showed that the samples of the ores contained 0.33 and 2.45% nickel feed grade for ore samples A and B, respectively. Batch flotation tests were performed on the ore samples using two different frothers namely Senfroth XP 200 and 516. Some of the nickel was found to be associated with the gangue minerals present in these ores and recoveries were based on the total nickel value. It was observed that 0.24 and 0.29% of the total 0.333% of the feed ore were recovered from sample A by Senfroth XP 516 and 200, respectively. The results also revealed that 1.77 and 2.13% of the total 2.45% of the feed ore were recovered from sample B by 516 and XP 200, respectively. Analysis of the results revealed that 0.07 and 0.04% of the nickel were recovered from the tailing by Senfroth XP 516 and 200, respectively from the ores grade sample A, while 0.53 and 0.30% of nickel were recovered from the tailing of sample B. It can be deduced from this work that Senfroth XP 516 is more selective for the recovery of nickel from nickel sulphide ore as compared to the Senfroth XP 200. The better performance of Senfroth XP 516 can be attributed to the better adsorption capacity and level of interaction of the Senfroth 516 and the dispersant employed in this study.

Numerical modelling of pollutant formation in a lifted methane–air vertical diffusion flame

Abstract A comparison of turbulence and combustion models have been performed for predicting CO2 and NOx formation from a methane diffusion flame firing vertically upwards. The flow field has been modeled using the Reynolds-Averaged Navier–Stokes equation incorporating the k-ε realizable turbulence closure model, the k-ω shear-stress transport (SST) turbulence model and the transitional SST turbulence model and the three models have been compared. Combustion was modeled using the unsteady Stationary Laminar Flamelet Model (SLFM), the Eulerian Particle Flamelet Model (EPFM), and the Pollutant Model (PM) and the three models have also been compared. Numerical predictions show good agreement with experimental data. Furthermore, the experimental data showed that the k-ε realizable turbulence model and the k-ω SST turbulence model performed better than transitional SST model in predicting the pollutant species from the flame. The result also shows that the PM performed better than flamelet models in predicting the combustion characteristics of NOX in the flame.

Optimization of Treatment Parameters on the Recycling of Used Lubricating Oil

Acid treatment is one of the cheapest techniques and least applicable processes in the recycling of used lubricating oils. In this work, the performance of sulphuric acid in the treatment used oil was studied. The effects of the critical treatment parameters (acid volume, concentration of the acid, treatment temperature, stirring time and treatment time) were investigated by varying one treatment parameter at a time and analysing metal content in the sample of the treated oil using atomic absorption spectrometry (ASS). Thereafter, an optimal solution was determined by the combination of the optimum values of each treatment parameters. The original conventional treatment parameter values, resulted in 13.2 ppm and thereafter was optimised to 11 ppm this showed a definite improvement in efficiency. This result is also comparable to other data obtained in previously studied work which employed the same conventional treatment parameters. The optimal solution is within 10% variation as compared the standard individual metal content which ranges 0-10 ppm.