Browsing by Author "Onyari, John Mmari"

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Adsorption of methylene blue dye from aqueous solutions using Eichhornia crassipes
(2013) Wanyonyi, Wycliffe Chisutia; Onyari, John Mmari; Shiundu, Paul M
Adsorption of methylene blue (MB) from aqueous solution using dried roots, stems, and leaves of Eichhornia crassipes biomass obtained from Lake Victoria was studied. Batch experimental results revealed that the adsorption process was highly dependent on adsorbent dosage, initial MB concentration, E. crassipes particle size and aqueous solution temperature. The isotherm data fitted Freundlich mathematical models with maximum dye adsorption of 35.37 mg g−1. Roots adsorbed over 99 % of the MB in <5 min. Sorption kinetics followed a pseudo-second-order model. Results provide evidence that E. crassipes is an effective and inexpensive biomaterial for dye removal from aqueous dye solutions and industrial effluents.
Adsorption of Pb (II) Ions from Aqueous Solutions by Water Hyacinth (Eichhornia Crassipes): Equilibrium and Kinetic Studies
(2014) Anzeze, Davis Amboga; Onyari, John Mmari; Gichuki, John W; Shiundu, Paul M
The Eichhornia crassipes roots for the removal of Pb (II) ions from aqueous solutions has been investigated. The adsorption of Pb (II) ions was found to be affected by solution pH, contact time, adsorbent dosage, initial metal ion concentration, and temperature. The equilibrium was analysed using Langmuir and Freundlich isotherm models. The data was found to have a closer correlation with the Freundlich isotherm as evidenced by a higher correlation coefficient (R2). The biosorption capacity for E. crasippes was found to be 16.350 mg g-1. The Kinetics data was also subjected to pseudo-first-order and the pseudo-second-order kinetic models. The data could be explained better using the pseudo-second-order kinetic model.
Biosorption of Malachite Green from Aqueous Solutions onto Polylactide/Spent Brewery Grains Films: Kinetic and Equilibrium Studies
(2012) Chanzu, Harry Amuguni; Onyari, John Mmari; Shiundu, Paul M
Batch experiments were conducted to study the biosorption of Malachite Green (MG) onto polylactide (PLA)/spent brewery grains (SBGs) films. Films were prepared by solvent-casting method using dichloromethane. Effects of contact time, pH, salt concentration, and optimal experimental condition was evaluated. At pH 6.89 and low salt concentration, Malachite Green was removed effectively. The isotherm data fitted the Freundlich model with 0.969 R2 value and 0.738 slope implying chemisorptions process. The biosorption process followed pseudo-second order kinetics with calculated adsorption capacity at equilibrium (qe) of 0.572 mg/g at 23 °C. The investigation showed that PLA/SBGs films are effective in dye removal from textile, paper and leather industries effluents.
Biosorption of Zn (II) ions from aqueous solutions by water hyacinth (Eichhornia crasippes): Equilibrium and Kinetic studies
(2014) Anzeze, Davis Amboga; Onyari, John Mmari; Shiundu, Paul M; Gichuki, John W
The biosorption characteristics of Zn (II) ions were investigated. Experimental parameters affecting the biosorption process such as pH, contact time, biomass dosage, initial metal ion concentration, and temperature were studied in batch adsorption experiments. Langmuir and Freundlich isotherm models were applied to the adsorption data .The biosorption capacity for E. crasippes was found to be 16.50 mg g-1. The data was also subjected to pseudo-first-order and the pseudo-second-order kinetic models.