Articles: Department of Physical Sciences: Recent submissions

Now showing items 21-40 of 59

Copper extraction by wet chemical method

Kugeria, Peterson M.; Mwangi, Isaac; Wachira, Jackson M.; Njoroge, Peter (Elsevier, 2018-07)

In many countries large deposits of copper with no locally established copper based industries occur because known methods for extraction are prohibitively expensive and unaffordable. This study reports on an affordable and ...
Properties of activated blended cement containing high content of calcined clay

Marangu, Joseph M.; Karanja, Thiong’o J.; Wachira, Jackson M. (Elsevier, 2018-08)

This paper presents findings of an experimental investigation on sodium sulphate (Na2SO4) activated calcined clay e Portland cement blends in sulphuric acid media. Calcined clays were blended with Ordinary Portland Cement ...
Review of Carbonation Resistance in Hydrated Cement Based Materials

Marangu, Joseph Mwiti; Thiong’o, Joseph Karanja; Wachira, Jackson M. (Hindawi, 2019)

Blended cements are preferred to Ordinary Portland Cement (OPC) in construction industry due to costs and technological and environmental benefits associated with them. Prevalence of significant quantities of carbon dioxide ...
Properties of activated blended cement containing high content of calcined clay

Mwiti, Marangu J.; Karanja, Thiong’o J.; Wachira, Jackson M. (Elsevier, 2018-08)

This paper presents findings of an experimental investigation on sodium sulphate (Na2SO4) activated calcined clay e Portland cement blends in sulphuric acid media. Calcined clays were blended with Ordinary Portland Cement ...
Carbon storage in the seagrass meadows of Gazi Bay, Kenya

Michael, Githaiga N.; Kairo, James G.; Gilpin2, Linda; Huxham, Mark (2017-05-10)

Vegetated marine habitats are globally important carbon sinks, making a significant contribution towards mitigating climate change, and they provide a wide range of other ecosystem services. However, large gaps in knowledge ...
Effects of Temperature on Ilmenite During Concentration of Iron in Laterites Using Charcoal and Separation using Magnetic Separation

Mutembei, Peterson K.; Muriithi, Naftali T.; Njoroge, Peter W.; Muthengia, Jackson W. (IJSET, 2014-06)

Effect of temperature on ilmenite minerals found in laterites has been investigated. It was found that during reduction of iron minerals in laterites to magnetite using charcoal at temperatures of about 500-700oC, ...
Magnetic Concentration of Iron in Lateritic Soils from Kamahuha, Murang’a County, in Kenya using Carbon Monoxide Generated In-Situ

Njoroge, P. W.; Mutembei, Peterson K.; Wachira, Jackson M.; Wanjau, R. (IJSET, 2014-08)

Chemical and Mineral Analyses of laterites from selected sites in Kamahuha area of Murang’a County, in the Republic of Kenya, have been carried out with particular interest in the levels of iron and the type of minerals ...
Physicochemical Performance of Portland-Rice Husk Ash-Calcined Clay-Dried Acetylene Lime Sludge Cement in Sulphate and Chloride Media

Wachira, Jackson M.; Thiong’o, Joseph K.; Marangu, Joseph M.; Murithi, Leonard G (Hindawi, 2019-03)

This paper reports leach and/or intake of SO42−, Cl−, Ca2+, Na+, and K+ from and/or into cement mortar cubes made from a novel cementious material in naturally encountered environmental simulated media. The paper also ...
Effects of Chlorides on Corrosion of Simulated Reinforced Blended Cement Mortars

Wachira, Jackson M. (Hindawi, 2019-03)

Cementitious materials are subject to degradation when subjected to corrosive chloride media. This paper reports the experimental results on corrosion studies conducted on a potential cementitious material, PCDC, made ...
Copper extraction by wet chemical method

Mutembei, Peterson K.; Wachira, Jackson M.; Mwangi, Isaac; Njoroge, Peter (Elsevier, 2018-07)

In many countries large deposits of copper with no locally established copper based industries occur because known methods for extraction are prohibitively expensive and unaffordable. This study reports on an affordable and ...
Review of Carbonation Resistance in Hydrated Cement Based Materials

Marangu, Joseph Mwiti; Thiong’o, Joseph Karanja; Wachira, Jackson M. (Hindawi, 2019-01)

Blended cements are preferred to Ordinary Portland Cement (OPC) in construction industry due to costs and technological and environmental benefits associated with them. Prevalence of significant quantities of carbon dioxide ...
Equilibrium Studies for Adsorption of Zn2+ on to Acid Treated Kikuyu Grass Pennisetum Clandestinum Biomass

Murithi, Genson; wa-Thiong’o, Karanja; Wachira, Jackson M. (2016-04)

The feasibility of using Pennisetum clandestinum biomass as low-cost adsorbent for the removal of Zn2+ was investigated in batch studies. The Freundlich, Langmuir,Dubinin Raduskevich and Temkin adsorption isotherms were ...
Thermoluminescence of SrAl2O4:Eu2þ, Dy3þ: Kinetic analysis of a composite-peak

Wako, Ali Halake; Chithambo, M. L.; Finch, A. A. (Elsevier, 2016-12)

The kinetic analysis of thermoluminescence of beta-irradiated SrAl2O4:Eu2þ,Dy3þ is reported. The glowcurve is dominated by an apparently-single peak. It has been demonstrated using a number of tests including partial ...
Effect of Ga3+ and Gd3+ ions substitution on the structural and optical properties of Ce3+-doped yttrium aluminium garnet phosphor nanopowders

Wako, Ali Halake; Dejenea, F. B.; Swart, H. C. (John Wiley & Sons, 2016-03)

ABSTRACT: The structural and optical properties of commercially obtained Y3Al5O12:Ce3+ phosphor were investigated by replacing Al3+ with Ga3+ and Y3+ with Gd3+ in the Y3Al5O12:Ce3+ structure to form Y3(Al,Ga)5O12:Ce3+ and ...
A preliminary study of Thermoluminescence of beta-irradiated SrAl2O4:Eu2+, Dy3+ phosphors

Wako, Ali Halake; Dejene, B. F.; Swart, H.C. (2015)

Eu2+ doped and Dy3+ co-doped strontium aluminate (SrAl2O4:Eu2+,Dy3+) phosphors were synthesized by the solution - combustion technique at 500 oC using urea as a reducer, a widely known method for preparing nano sized ...
Characterization of cerium doped yttrium gadolinium aluminate garnet (Y-Gd)3Al5O12:Ce3+ phosphor thin films fabricated by pulsed laser deposition

Wako, Ali Halake; Dejene, F. B.; Swart, H.C. (2015)

Thin films of cerium doped yttrium gadolinium aluminate garnet (Y-Gd)3Al5O12:Ce3+ (YGAG:Ce) were grown on Si(100) substrates by a pulsed laser deposition (PLD) technique using a 266 nm Nd:YAG pulsed laser under varying ...
Influence of alkaline earth metal cations; Ca2+, Sr2+ and Ba2+ on the structural and optical properties of MAl2O4: Eu2+, Nd3+ phosphors.

Wako, Ali Halake; Dejene, F. B.; Swart, H.C. (2014)

Eu2+ doped and Nd3+ co-doped MAl2O4:Eu2+, Nd3+ (M = Ca, Sr, and Ba) phosphors were prepared by a solution-combustion method. The obtained powders were investigated in terms of their phase composition, particle morphology ...
Combustion synthesis, characterization and luminescence properties of barium aluminate phosphor

Wako, Ali Halake; Dejene, F. B.; Swart, H.C. (Elsevier, 2014-09)

The blue-green emitting Eu2+ and Nd3+ doped polycrystalline barium aluminate (BaAl2O4:Eu2+,Nd3+) phosphor, was prepared by a solution-combustion method at 500 °C without a post-annealing process. The characteristic variation ...
Properties of blue emitting CaAl2O4:Eu2+, Nd3+ phosphor by optimizing the amount of flux and fuel

Wako, Ali Halake; Dejene, B. F.; Swart, H.C. (Elsevier, 2014-04)

Long afterglow CaAl2O4:0.03Eu2+, 0.03Nd3+ phosphor was prepared by solution-combustion synthesis. The active role of boric acid (H3BO3) as a flux in enhancing the Eu2+ photoluminescence and the effect of a varied amount ...
Roles of doping ions in afterglow properties of blue CaAl2O4:Eu2+,Nd3+ phosphors

Wako, Ali Halake; Dejene, B. F.; Swart, H.C. (2014-04)

Eu2+ doped and Nd3+ co-doped calcium aluminate (CaAl2O4:Eu2+,Nd3+) phosphor was prepared by a urea-nitrate solution combustion method at furnace temperatures as low as 500 °C. The produced CaAl2O4:Eu2+,Nd3+ powder was ...

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