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Browsing Physical and Chemical Sciences by Subject "Adsorption"
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Item Biosorption of nickel from aqueous solution by Tithonia diversifolia(Taylor and Francis, 2012-08-03) Olasehinde, Emmanuel F.; Okoronkwo, Afamefuna E.; Aiyesanmi, Ademola F.This study investigated the feasibility of Mexican sunflower (Tithonia diversifolia), a common plant that inhabits the highway of the south western Nigeria, as a novel biosorbent for nickel from solutions. pH profile, time dependency and cation interference studies were conducted using stem biomass of this plant. Nickel uptake exhibited substantial enhancement both in terms of the kinetics of uptake as well as the loading capacity. Results of the investigation showed that the unmodified biomass was able to remove over 70% of the nickel content of a solution, whereas NaOH modification improved the adsorption efficiency to over 77% in the same contact time of 60 min. The optimum pH of adsorption was recorded as 5 for the metal using both types of biomass. However,modification improved the adsorption efficiency to a pH lower than 4. The kinetic study conducted showed that the adsorption process follows Lagergren’s pseudo-second order reaction with R2 values equal to 0.9988 and 0.9989 for both types of biomass. The presence of cations such as calcium and magnesium also interfered negatively with the adsorption process. Between 20–35% reductions in the metal adsorbed were recorded in the presence of a 1 M concentration of Mg, Ca or mixed Mg and Ca ions. Langmuir model of adsorption isotherm gave the best fit for this sorption process with R2 values of 0.994, 0.995 and 0.997 for Mg, Ca and mixed Mg and Ca studies, respectively.Item Cadmium (II) Adsorption from Aqueous Solutions Using Onion Skins(SpringerLink, 2019-11-18) Olasehinde, Emmanuel F.; Adegunloye, Ajibola V.; Adebayo, Matthew A.; Oshodi, Aladesanmi A.The potential of onion skins for removal of aqueous Cd(II) was investigated. Onion skin powder was chemically modified using thioglycolic acid to develop a suitable, low-cost, and efficient adsorbent for the removal of Cd(II) from aqueous solutions. Influences of temperature, contact time, initial concentration of Cd(II), adsorbent dosage, and pH on the removal of Cd(II) were probed. Optimal adsorption conditions were found at pH 5 and 4, and at 60- and 30-min equilibrium time for the modified and native onion skins, respectively. The equilibrium process was well described by the Freundlich isotherm model. The maximum Cd(II) adsorption capacities, from the Langmuir model, are 17.86 mg/g (modified) and 21.28 mg/g (native). The adsorption process followed the mechanism of physisorption. Pseudo second-order rate equation fitted the kinetic data better than the pseudo first-order rate equation for the two adsorbents. Thermodynamic parameters, such as standard free energy change (ΔG°), standard enthalpy change (ΔH°), and standard entropy change (ΔS°), were calculated for adsorption experimental studies. The results showed that the adsorption of Cd(II) on native/unmodified and modified onion skins was a feasible process and exothermic under the studied conditions. The Cd(II) adsorbed was efficiently desorbed from adsorbent using 0.3 M HCl.Item Inhibitory Action of Nicotiana tabacum Extracts on the Corrosion of Mild Steel in HCl: Adsorption and Thermodynamics Study(Science Pub, 2012-06) Olasehinde, Emmanuel F.; Olusegun, S. J.; Adesina, A. S.; Omogbehin, S. A.; Momoh, Yahayah H.The toxic effects of synthetic corrosion inhibitors have led to the search for naturally occurring substances which are not only readily available but are also environmentally friendly. Therefore, this study investigates the inhibition efficacy of acid extract of Nicotiana tabacum leaves on mild steel in 1M HCl using weight loss method. Experiments are performed by varying immersion period, concentration of the inhibitor and temperature. The inhibition efficiency is markedly higher on the addition of Nicotiana tabacum leaves extract in acidic medium compared with those in the absence of inhibitor. The inhibition efficiency increased with an increase in inhibitor concentration but decreased with rise in temperature and exposure time. Thermodynamic studies revealed that corrosion inhibition may be due to the spontaneous physical adsorption of the plant constituents on the surface of mild steel. Experimental data fitted with the Langmuir and Temkin adsorption isotherms. Kinetic treatment of the data followed a first order reaction. Calculated half-lives increase as the concentration of the extracts increases suggesting that inhibition efficiency increases with increase in the concentration of the extracts.Preliminary investigation of the phytochemical constituents showed that Nicotiana tabacum contains tannin,flavonoid, terpenoid and some other compounds in trace constituents. [Olasehinde, EF, Olusegun, SJ, Adesina, AS, Omogbehin, SA, Momoh-Yahayah, H. Inhibitory Action of Nicotiana tabacum Extracts on the Corrosion of Mild Steel in HCl: Adsorption and Thermodynamics StudyItem Synthesis and crystal structure of Cd-based metal-organic framework for removal of methyl-orange from aqueous solution(Elsevier, 2017-07-21) Tella, Adedibu C.; Olawale, Margaret D.; Neuburger, Markus; Obaleye, Joshua A.A novel [Cd(INA)2(H2O)]. ISB (1) (INA = isonicotinate; ISB = isobutanol) was synthesized through the reaction between the isonicotinic acid ligand and cadmium (II) salt and characterized by elemental analysis, FTIR and UV–Visible spectroscopies, SEM and Single crystal X-ray diffraction. The crystal is orthorhombic, space group Pbca, a = 12.24(10) Å, b = 15.4646(13) Å, c = 18.8445(17) Å, V = 3569(3) Å3, Z = 8. The pentagonal bipyramid (seven coordinate) around the cadmium (II) ion is of the form CdN2O5 coordinating to four oxygen atoms from carboxylates, one oxygen atom from water molecule and two nitrogen atoms of pyridine. The structure of compound is stabilized by two hydrogen bonds namely intermolecular (O-H–O) and intramolecular type C-H– O accounting for polymeric nature of the metal-organic frameworks. 1 was studied for adsorptive removal of methyl orange (MO) from aqueous solution. Equilibrium isotherm study reveals that Langmuir model gave a better fitting result than the Freundlich model. The pseudo-second order model could be used to interpret adsorption kinetics. The maximum adsorption capacity calculated by Langmuir was 166 mg/g at 300 K. These results indicate the adsorption of MO on 1 is partly due to electrostatic interaction between methyl orange and the adsorbent. 1 could be used as adsorbent to remove methyl orange from aqueous solution.