U. Akpan

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Papers by U. Akpan

Effects of Process Variables and a Comparative Study of Methods for Transfer Oil Production from Spent Engine Oil

by U. Akpan and Moses Olutoye

Optimization of Base Oil Regeneration from Spent Engine Oil via Solvent Extraction

by U. Akpan and Moses Olutoye

Preservation of Passion Fruit Juice

by Mohammed Abubakar and U. Akpan

Production and preservation of Passion Fruit Juice was examined to reduce the spoilage and to inc... more Production and preservation of Passion Fruit Juice was examined to reduce the spoilage and to increase the shelf life of the juice using chemical preservatives. The preservation of the juice was carried out using sugar, benzoic acid, citric and a combination of citric and benzoic acid under room temperature. The result revealed that the juice maintained its color, aroma and

Extraction, Characterization and Modification of Castor Seed Oil

This paper carried out experimental study, through extraction and characterization of both crude ... more This paper carried out experimental study, through extraction and characterization of both crude and refined castor oil. Normal hexane was used as solvent for the extraction process. The oil produced was refined through degumming, neutralization and bleaching process using local adsorbent (activated clay). The characterization analysis revealed that tested parameters, which include specific gravity, refractive index, acid value, saponification value

Photocatalytic degradation of 2,4-dichlorophenoxyacetic acid by Ca–Ce–W–TiO 2 composite photocatalyst

Chemical Engineering Journal - CHEM ENG J, 2011

A Ca–Ce–W–TiO2 composite photocatalyst has been developed which was efficient in the degradation ... more A Ca–Ce–W–TiO2 composite photocatalyst has been developed which was efficient in the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D). The adsorption rate constant obtained from the Langmuir–Hinshelwood kinetic model was in the order of 1:287:adsorption:reaction, which is so negligible. This is an indication that the process did not obey the Langmuir–Hinshelwood kinetic model. Therefore, the degradation recorded in this study was as a result of the properties of the composite photocatalyst. Large specific surface area, reduced band gap which also inhibited electron–hole recombination, high crystallinity of the composite photocatalyst were responsible for its efficiency. The photocatalytic process in this study is best described by the first order irreversible reaction rate/order. A comparison of the efficiency of the photocatalyst with a commercially available photocatalyst, TiO2–Sigma product and other photocatalysts in literature placed the composite photocatalyst at an excel...

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Parameters affecting the photocatalytic degradation of dyes using TiO 2 -based photocatalysts: A review

by U. Akpan and Bassim H Hameed

This paper presents the review of the effects of operating parameters on the photocatalytic degra... more This paper presents the review of the effects of operating parameters on the photocatalytic degradation of textile dyes using TiO 2-based photocatalysts. It further examines various methods used in the preparations of the considered photocatalysts. The findings revealed that various parameters, such as the initial pH of the solution to be degraded, oxidizing agents, temperature at which the catalysts must be calcined, dopant(s) content and catalyst loading exert their individual influence on the photocatalytic degradation of any dye in wastewaters. It was also found out that sol–gel method is widely used in the production of TiO 2-based photocatalysts because of the advantage derived from its ability to synthesize nanosized crystallized powder of the photocatalysts of high purity at relatively low temperature.

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Enhancement of the photocatalytic activity of TiO2 by doping it with calcium ions

Journal of Colloid and Interface Science, 2011

Titanium dioxide (TiO(2)) with an enhanced photocatalytic activity was developed by doping it wit... more Titanium dioxide (TiO(2)) with an enhanced photocatalytic activity was developed by doping it with calcium ions through a sol-gel method. The developed photocatalysts were characterized by Fourier transform infrared (FTIR) spectroscopy, N(2) physisorption, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction. Their surface morphologies were studied using surface scanning electron microscopy (SEM). The XPS analyses confirmed the presence of Ti, O, Ca, and C in the Ca-doped TiO(2) sample. The activities of the catalysts were evaluated by photocatalytic degradation of an azo dye, acid red 1 (AR1), using UV light irradiation. The results of the investigations revealed that the samples calcined at 300 °C for 3.6h in a cyclic (2 cycles) mode had the best performance. Lower percentage dopant, 0.3-1.0 wt.%, enhanced the photocatalytic activity of TiO(2), with the best at 0.5 wt.% Ca-TiO(2). The performance of 0.5 wt.% Ca-TiO(2) in the degradation of AR1 was far superior to that of a commercial anatase TiO(2) Sigma product CAS No. 1317-70-0. The effect of pH on the degradation of AR1 was studied, and the pH of the dye solution exerted a great influence on the degradation of the dye.

Production and Preservation of Passion Fruit Juice

Leonardo Journal of Sciences, 2005

Production and preservation of Passion Fruit Juice was examined to reduce the spoilage and to inc... more

Photocatalytic degradation of Acid Red 1 dye using ZnO catalyst in the presence and absence of silver

Desalination and Water Treatment, 2011

The investigation of the degradation of Acid Red 1 (AR1) dye was carried out in an aqueous suspen... more The investigation of the degradation of Acid Red 1 (AR1) dye was carried out in an aqueous suspension photoreactor. Different parameters that affect the degradation of AR1 dye such as the presence and absence of a photocatalyst, light source, air, catalyst loading, initial substrate concentration were studied. The activity of Ag-doped ZnO prepared by photoreduction of Ag ion on ZnO catalyst for AR1 dye degradation was investigated. The effects of different amount of Ag deposited on ZnO particles and catalysts loading on the photocatalytic degradation rate of AR1 dye were evaluated. The surface morphologies of both Ag-doped ZnO and ZnO catalysts were studied by scanning electron microscopy (SEM), while X-ray diffraction (XRD) was used to study the crystallography of the catalysts. The experimental results revealed that the presence of photocatalyst, light, and air are signifi cant for the photodegradation process. The optimum catalyst loading was 2 g catalyst per liter solution. The presence of Ag in the catalyst does not significantly enhance the photocatalytic activity of ZnO in the degradation process.

A comparative study of the photocatalytic efficiency of Degussa P25, Qualigens, and Hombikat UV-100 in the degradation kinetic of congo red dye

by U. Akpan and Suhas Patil

Desalination and Water Treatment, 2012

The photocatalytic efficiency of three TiO2 photocatalysts; Degussa P25, Qualigens, and Hombikat ... more The photocatalytic efficiency of three TiO2 photocatalysts; Degussa P25, Qualigens, and Hombikat UV 100 has been investigated on the degradation kinetic of congo red dye. The crystal phases, structures, and crystallite sizes of the catalysts were analyzed by X-ray diffraction, microstructure, and morphology by transmission electron microscopy, and surface area and pore-size distributions by nitrogen physisorption. The results of the

Development and photocatalytic activities of TiO 2 doped with Ca–Ce–W in the degradation of acid red 1 under visible light irradiation

Desalination and Water Treatment, 2013

ABSTRACT A stable visible light photocatalyst has successfully been developed by doping titanium ... more ABSTRACT A stable visible light photocatalyst has successfully been developed by doping titanium dioxide (TiO2) with Ca, Ce, and W. Various combinations were developed and tested. The photocatalyst, when subjected to visible light photocatalytic degradation of C.I. Acid red 1 (AR1) showed an excellent performance in comparison with the most acclaimed commercial TiO2 photocatalyst, Degussa P25. The photocatalytic process with the best developed photocatalyst is “initial-concentration”-dependent, as high initial concentrations of AR1 dye precluded the photon energy from reaching the photocatalyst, and hence reduced its degradation rate. Initial pH of dye solution exerts its influence on the visible light photocatalytic degradation of the dye. High initial pH 10 was detrimental to the process, while the process was controlled by adsorption at lower pH 3. The developed photocatalysts were characterized by X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectra, X-ray diffraction, N2 physisorption, surface scanning electron microscopy, and fourier transform infra-red spectroscopy. The results showed a red shift in the band gap of the tri-doped TiO2 from 3.2 to 2.94 eV indicating a shift in the onset optical wavelength from 387.19 to 421.43 nm.

Photocatalytic activity of sol–gel-derived mesoporous TiO 2 thin films for reactive orange 16 degradation

Desalination and Water Treatment, 2013

ABSTRACT This study investigates the photocatalytic activity of sol–gel-derived mesoporous TiO2 t... more ABSTRACT This study investigates the photocatalytic activity of sol–gel-derived mesoporous TiO2 thin films for reactive orange 16(RO16) degradation. Both surfactant- and non-surfactant-assisted sols were prepared and coated on different glass slides. The prepared catalysts were characterized by X-ray diffraction, surface scanning electron microscopy, UV–vis transmittance spectra, and nitrogen adsorption/desorption isotherms for their properties, while the photocatalytic activities of the TiO2 thin films were evaluated in the degradation of RO16. The surfactant-assisted films showed surface uniformity, reduced particle size, and high photocatalytic activity compared to non-surfactant assisted films. The effects of withdrawal speed on films’ transparency and the number of coatings on UV light absorption and their photocatalytic activities are systematically explained for the surfactant-assisted films. Though there was a continuous increase in the efficiency of the mass of TiO2 per unit area and UV light absorption with the increase in the number of dip-coatings, any further increase in the number of coatings beyond five did not show any significant increase in the degradation rate, indicating that further coatings resulted in the blocking of middle pores.

Solar degradation of an azo dye, acid red 1, by Ca–Ce–W–TiO2 composite catalyst

Chemical Engineering Journal, 2011

An electronically stable composite photocatalyst of the type Ti(1−x−y)Ca(3x−y)Ce(2x−y)W(y/6)O2(1−... more An electronically stable composite photocatalyst of the type Ti(1−x−y)Ca(3x−y)Ce(2x−y)W(y/6)O2(1−2(y−x)) (at y&amp;lt;2x and x+y&amp;lt;1) with an enhanced solar photocatalytic activity was developed by doping TiO2 with Ca, Ce and W. The catalyst was prepared by sol–gel method and hydrothermally treated before used in the solar photocatalytic degradation of an azo dye, acid red 1 (AR1). To verify the effectiveness of the

The production of ethanol from maize cobs and groundnut shells

by Mohammed Abubakar and U. Akpan

AU J Technol, 2005

... Adv. Biotech J. 2: 105-11. Gordon, GB; and Michael, S. 1979. Food Science. pp. 21, 37-97. Per... more

Extraction, characterization and modification of castor seed oil

Leonardo Journal of Sciences, 2006

... Department of Chemical Engineering, Federal University of Technology, Minna PMB 65, Niger Sta... more

The advancements in sol–gel method of doped-TiO 2 photocatalysts

by U. Akpan and Bassim H Hameed

A critical review on the advancements in sol–gel method of doping TiO2 photocatalysts is provided... more A critical review on the advancements in sol–gel method of doping TiO2 photocatalysts is provided.
Various sol–gel and related systems of doping were considered, ranging from co-doping, transition metal
ions doping, rare earth metal ions doping to other metals and non-metals ions doping of TiO2. The results
available showed that doping TiO2 with transition metal ions usually resulted in a hampered efficiency of
the TiO2 photocatalyst, though in some few cases, enhancements of the photocatalytic activity of TiO2
were recorded by doping it with some transition metal ions. In most cases, co-doping of TiO2 increases
the efficiency of its photocatalytic activity. The review reveals that there are some elemental ions that
cannot be used to dope TiO2 because of their negative effects on the photocatalytic activity of the
catalyst, while others must be used with caution as their doping will create minimal or no impacts on the
TiO2 photocatalytic efficiency

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