ABSTRACT
Ca and Mg have been implicated in causing hardness in beans resulting in relatively long cooking time. This study used potassium to replace the cations and determined the adsorption of potassium solution to bean seeds. Then, plantain peel, a natural source of potassium, was used to cook beans and its impact on the cooking time of beans was investigated. The adsorption experiments were performed using batch technique, while metal compositions of the bean seeds and plantain peel were determined by spectroscopy. Optimum removal conditions of potassium ion biosorption using bean seeds were observed at pH 10.2, 2 g bean seed dosage, 180 min agitation time, with 75 ppm as initial metal concentration. The kinetic model correlate with pseudo-second order reaction and the Langmuir adsorption model best fitted the adsorption. After cooking the beans with plantain peel, the concentration of Mg reduced in the bean seeds by about 48%, while the concentration of Ca reduced by about 22%, but the concentration of K increased by over 200% in the cooked bean seeds. Beans treated with plantain peel cooked earlier than the control experiment. This may be affected by pH, adsorbent dosage, metal concentration and contact time.
ABSTRACT
This work evaluated the use of Dialium guineense seed waste (DGS) and its sodium hydroxide modified form (NH-DGS) as biosorbent for ciprofloxacin (CPF) from synthetic solution as well as the desorption potentials. Central composite design (CCD) was applied for optimization of the alkaline treated biosorbent by response surface methodology using design expert. Both biosorbents were characterized by FTIR, SEM, EDX, and BET analysis. The CCD showed NaOH concentration of 0.46 M and temperature of 96 °C to be effective for optimized modification of NH-DGS. Optimum removal of CPF was obtained at pH 6.0, contact time 120 min, temperature 300 K, and dosage of 0.1 g. The Freundlich model gave the best fit compared to the other isotherms tested with R2 values >0.97951. NH-DGS exhibited a maximum uptake capacity of 120.34 mg/g higher than some reported adsorbents for CPF. The pseudo-second-order model was suitable in the fitting of the kinetic data. A non-spontaneous process was obtained for CPF biosorption on DGS which became spontaneous after alkaline treatment. Over 84% desorption of CPF was achieved on both biosorbents using 0.3 M HCl which envisaged the use of NH-DGS as an efficient material for treatment of waters contaminated with CPF.
Subject(s)
Ciprofloxacin , Water Pollutants, Chemical/analysis , Adsorption , Biodegradation, Environmental , Hydrogen-Ion Concentration , Kinetics , Powders , Seeds , ThermodynamicsABSTRACT
Cd(II) and Pb(II) ions removal using adsorbents prepared from sub-bituminous coal, lignite, and a blend of coal and Irvingia gabonensis seed shells was investigated. Fourier transform infrared, scanning electron microscope and X-ray fluorescence analyses implicated hydroxyl, carbonyl, Al2O3, and SiO2 as being responsible for attaching the metal ions on the porous adsorbents. The optimum adsorption of carbonized lignite for the uptake of Cd(II) and Pb(II) ions from aqueous media were 80.93 and 87.85%, respectively. Batch adsorption was done by effect of adsorbent dosage, pH, contact time, temperature, particle size, and initial concentration. Equilibrium for the removal of Pb(II) and Cd(II) was established within 100 and 120 min respectively. Blending the lignite-derived adsorbent with I. gabonensis seed shell improved the performance significantly. More improvement was observed on modification of the blend using NaOH and H3PO4. Pb(II) was preferentially adsorbed than Cd(II) in all cases. Adsorption of Cd(II) and Pb(II) ions followed Langmuir isotherm. The adsorption kinetics was best described by pseudo-second order model. The potential for using a blend of coal and agricultural byproduct (I. gabonensis seed shell) was found a viable alternative for removal of toxic heavy metals from aqueous solutions.
