Kinetics, Isotherms and Thermodynamics Studies of Sorption of Cu2+ onto Novel Zerovalent Iron Nanoparticles

A novel nanoscale zerovalent iron (nZVI) is an effective adsorbent forscavenging inorganic and organic toxicants. nZVI was synthesized in a single potsystem using bottom-up approach and were characterized by BET, SEM, EDX andFTIR. In this study, sorption of Cu2+ onto nZVI was carried out vis-à-vis theinvestigation of physicochemical parameters (initial metal ion concentration, pH,temperature, adsorbent dose) at 298 K. The sorption data obtained at optimumconditions were subjected to six different isotherm models (Langmuir, Freundlich,Temkin, Dubinin-Raduskevich (D-R), Halsey and Harkin-Jura). However, theequilibrium sorption data were best described by both Langmuir and Temkin isothermmodels with Langmuir maximum monolayer coverage (Qmax) of 40.816 mg/g andregression correlation value (R2 > 0.96) supporting a chemisorption mechanism. Pseudofirst-and second-order, Elovich, fractional power and intra-particle diffusion modelswere applied to the adsorption data in order to investigate the kinetic process; pseudosecond-order fitted the data most. The intra-particle diffusion model suggested that theintra-particle diffusion was one of the rate-limiting steps. The values of the Gibbs freeenergy showed the feasibility and spontaneity of the sorption process. The removalefficiency of Cu2+ (> 98%) onto zerovalent iron nanoparticles revealed that nZVI is apromising and efficient adsorbent that can be utilized by industries on a large scale forwaste treatment.Keywords: Zerovalent Iron nanoparticle; Sorption; Isotherms; Kinetics andThermodynami

Kinetics and Thermodynamics of Adsorption of Rhodamine B onto Bentonite Supported Nanoscale Zerovalent Iron Nanocomposite

Bentonite clay supported nanoscale zerovalent iron (BC-nZVI) composite was successfully prepared. BC-nZVI was characterized by physicochemical and spectroscopic techniques. Surface area as determined by sear’s method is 291.2 cm2 . Adsorption operational parameters were investigated in a batch technique. At 500 mg/L initial concentration, 120 minutes contact time and pH 3, 454.81 mg/g quantity was adsorbed. The highest adsorption percentage removal efficiency was obtained at room temperature. Kinetic data fitted best to pseudo second order and the mechanism was diffusion governed. The kinetic models were further validated by sum of square error (SSE) and non-linear Chi-square statistical models (X 2). The values of the thermodynamic parameters: standard enthalpy change ΔH (- 10.597 Jmol -1 )to (-5558 Jmol -1.), standard entropy change, ΔS (-277.804 J mol -1 K -1 )- to (-139.2595 J mol - 1 K -1) and the Gibbs free energy (ΔG) revealed that the adsorption process was feasible, spontaneous and exothermic in nature. The performance of BC-nZVI enlisted it as a great potential adsorbent for effective removal of Rhodamine B and therefore recommended for application in industrial effluent treatment

Exploring the Effect of Operational Factors and Characterization Imperative to the Synthesis of Silver Nanoparticles

The synthesis and application of silver nanoparticles are increasingly becoming attractive. Hence, a critical examination of the various factors needed for the synthesis of silver nanoparticles as well as the characterization is imperative. In light of this, we addressed in this chapter, the nitty-gritty on the operational parameters (factors) and characterization relevant to synthesis of silver nanoparticle. The following characterization protocols were discussed in the context of silver nanoparticle synthesis. These protocols include spectroscopic techniques such as ultraviolet visible spectroscopy (UV –Vis, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS)

Kinetics and isotherm modeling of adsorption of rhodamine B dye onto chitosan supported zerovalent iron nanocomposite (C-nZVI)

The kinetics and isotherm modeling of adsorption of Rhodamine B (RhB) Dye onto chitosan supported zerovalent iron nanocomposite (C-nZVI) was successfully studied in a batch technique. The quantity adsorbed increased with increase in initial concentration from 49.33 mg – 242.37 mg for 200 ppm to 1000 ppm and high percentage removal efficiency (%RE) of 99.72% attained at 90 minutes contact time. Equilibrium data were analyzed by six isotherm models: Langmuir, Freundlich, Temkin, Dubinin-Kaganer-Raduskevich (DKR), Redlich-peterson and Halsey isotherm model. Equilibrium data best fitted to Freundlich isotherm supported by Halsey isotherm model. Langmuir monolayer adsorption capacity (256.41 mg/g) of C-nZVI obtained greater than most adsorbent reported for adsorption of RhB. The mean adsorption free energy, E per molecule evaluated from DKR model was less than 8 KJmol -1 indicating a physisorption mechanism. The kinetic data best fitted to pseudo second-order kinetic model as validated by sum of square error (SSE) statistical model and the mechanism controlled by pore dif usion. The study revealed the great potential of C-nZVI for ef ective removal of RhB dye. C-nZVI is therefore recommended for civic and industrial ef luents treatment

Improved Parton Showers at Large Transverse Momenta

Several methods to improve the parton-shower description of hard processes by an injection of matrix-element-based information have been presented over the years. In this article we study (re)weighting schemes for the first/hardest emission. One objective is to provide a consistent matching of the POWHEG next-to-leading order generator to the Pythia shower algorithms. Another is to correct the default behaviour of these showers at large transverse momenta, based on a comparison with real-emission matrix elements

Prophylactic Effect of Aqueous Extract of Moringa oleifera Lam Leaves against Gamma Radiation Induced Damage on the Haematopoietic Cell Count in Adult Male Wistar Rats

Moringa oleifera plant has been reported to have antioxidant properties which aroused the search for its radioprotective effects.This study is expected to highlight the possible prophylactic role of aqueous extract of Moringa oleifera leaves following exposure to radiation.A total of 90 Wistar rats were divided into six groups of fifteen rats each. Theseare: group 1 (control without radiation or moringa extract), group 2 (50 mg/kg b. wt. of aqueous extract of M. oleifera), group 3 (100 mg/kg b. wt. of aqueous extract of M. oleifera leaf), group 4 (2.5 Gy of gamma radiation only), group 5 (50 mg/kg b. wt. of M. oleifera + 2.5 Gy of gamma radiation), group 6 (100 mg/kg b. wt. of M. oleifera + 2.5 Gy gamma radiation).Two hours after the final administration on the fifth day, selected rats were exposed to a single dose of 2.5 Gy gamma radiation. The animals were sacrificed at on days 2, 7 and 14 after irradiation. Exposure to the 2.5 Gy showed significant decrease in the WBC, PLT, RBC, HGB, LYM while no significant changes was noted in the MCV throughout the three timelines used for this study. However, pre-treatment with aqueous extract of M. oleifera leaves was observed to reduce these detrimental effects. Thus, aqueous extract of M. oleifera leaves has the prophylactic potency to help reduce radiation damage to the haematopoietic system

Bottom-up approach synthesis of core-shell nanoscale zerovalent iron (CS-nZVI): Physicochemical and spectroscopic characterization with Cu(II) ions adsorption application

Single pot system in chemical reduction via bottom-up approach was used for the synthesis of core shell nanoscale zerovalent iron (CS-nZVI). CS-nZVI was characterized by a combination of physicochemical and spectroscopic techniques. Data obtained showed BET surface area 20.8643 m2/g, t-Plot micropore volume 0.001895 cm3/g, BJH volume pores 0.115083 cm3/g, average pore width 186.9268 Å, average pore diameter 240.753 Å, PZC 5.24, and pH 6.80. Surface plasmon Resonance from UV-Vis spectrophotometer was observed at 340 nm. Surface morphology from SEM and TEM revealed a spherical cluster and chain-like nanostructure of size range 15.425 nm −97.566 nm. Energy Dispersive XRF revealed an elemental abundance of 96.05% core shell indicating the dominance of nZVI. EDX showed an intense peak of nZVI at 6.2 keV. FTIR data revealed the surface functional groups of Fe–O with characteristics peaks at 686.68 cm−1, 569.02 cm−1 and 434 cm−1. In a batch technique, effective adsorption of endocrine disruptive Cu(II) ions was operational parameters dependent. Isotherm and kinetics studies were validated by statistical models. The study revealed unique characteristics of CS-nZVI and its efficacy in waste water treatment

Kinetics and Equilibrium Models for Sorption of Cu(II) onto a Novel Manganese Nano-adsorbent

The studies of kinetics and equilibrium sorption of Cu(II) were undertaken using nanoscale zerovalent manganese (nZVMn) synthesized by chemical reduction in a single pot system. nZVMn was characterized using scanning electron microscopy, energy dispersive x-ray, and surface area determined by Brunauer–Emmett–Teller. The effect of pH, contact time, adsorbent dose, agitation speed, initial Cu(II) concentrations, temperature, and ionic strength on the sorption of Cu(II) onto nZVMn were investigated in a batch system. The kinetic data followed pseudo-second-order. The mechanism was governed by pore diffusion. The equilibrium sorption data were tested by Freundlich, Langmuir, Temkin, Dubinin–Kaganer–Raduskevich, and Halsey isotherm models. The Langmuir monolayer adsorption capacity (Qmax = 181.818 mg/g) is much greater compared to other nano-adsorbents used in sorption of Cu(II). The thermodynamic parameters (∆Ho, ∆So, ∆Go) revealed a feasible, spontaneous, and endothermic adsorption process. nZVMn has a great potential for effective removal of copper (II) in aqueous solution

Abstinence sexuelle du postpartum et les types d'allaitement a Shagamu, Nigeria

This was a prospective study involving 371 mothers. The mean age of the mothers was 27.5 (.3.6) years with a mean years at school (Educational years) of 11.3 (2.9) years. All the mothers had previously breastfed at one of their infants for at least 6 months, while the mothers also breastfed their last child for an average (mean) of 10.3 (4.0) months. The overall mean of previous live births was 1.9 (0.8). In the first month postpartum, 84.6% of the mothers abstained from sexual intercourse, but by the 4th-5th month the proportion had dropped to 18.1%, with just 2.1% of the study population abstaining from sexual intercourse at 11-15 months post-partum. Forty seven (13.5%), 30 (8.6% ) and 3 (0.9 % ) mothers in social classes 2,3 and 1 respectively have resumed sexual intercourse at 4-5 months, while only 12(3.4%) and 4(1.1%) in social classes 2 and 3 respectively continued with sexual intercourse at 11-15 months. More mothers resumed sexual intercourse from 1 to 15 months post-partum when they breast fed for 6-10 minutes and 11-15 minutes than those who breast fed for 1-5 minutes, 16-20 minutes and 21-25 minutes. Also more mothers within the 25-29 years age group resumed sexual intercourse from the first month to the fifteenth month post-partum than mothers in the other age groups.Il s'agit d'une étude prospective concernant 371 mères. L'âge moyen de ces mères était de 27,5 (.3,5) ans ainsi qu'un âge moyen à l'école (des années scolaires) de 11,3 (2,9) ans. Toutes les mères ont allaité au moins un de leurs enfants pendant six mois alors que les mères ont aussi allaité leur dernier enfant pendant un moyen de 10,3 (4 mois). Le moyen global des naissance vivantes précédentes était de 1,9 (0,8). En ce qui concerne le postpartum du premier mois, 84,6% des mères se sont abstenues des rapports sexuels mais vers les 4ème et 5ème mois, le chiffre a chuté jusqu' à 18,1%, mais il n'y avait que 2,1% de la population étudiée qui se sont abstenues des rapports sexuels au cours de la période de 11 - 15 mois du postpartum. Quarante - sept (13,5%) 30 (8,6%) et 3 (0,9%) mères appartenant aux clases sociales 2,3 et 1 respectivement ont repris les rapports sexuels après 4-5 mois, alors que (12 (3,4%) et 4 (1, 1%) dans les classes sociales 2 et 3 respectivement ont continué les rapports sexuels après 11 - 15 mois. Il y a eu encore des mères qui ont repris les rapports sexuels à partir d'un mois jusqu'à 15 mois du postpartum quand elles ont allaité pour 6 - 10 minutes et 11 - 15 minutes plus que celles qui ont allaité pour 1 - 5 minutes 16 - 20 minutes et 21 - 25 minutes. Il y avait plus des femmes du groupe d'âge de 25 - 29 ans qui avaient repris les rapports sexuels à partir du premier mois jusqu'au quinzième mois du postpartum que les mères dans d'autres groupes d'âge

KINETICS AND ISOTHERM MODELING OF ADSORPTION OF RHODAMINE B DYE ONTO CHITOSAN SUPPORTED ZEROVALENT IRON NANOCOMPOSITE (C-nZVI)

The kinetics and isotherm modeling ofadsorption ofRhodamine B (RhB) Dye onto chitosan supported zerovalent iron nanocomposite (C-nZVI) was successfully studied in a batch technique. The quantity adsorbed increased with increase in initial concentration from 49.33 mg – 242.37 mg for 200 ppm to 1000 ppm and high percentage removal efficiency (%RE) of 99.72% attained at 90 minutes contact time. Equilibrium data were analyzed by six isotherm models: Langmuir, Freundlich, Temkin, Dubinin-Kaganer-Raduskevich (DKR), Redlich-peterson and Halsey isotherm model. Equilibrium data best fitted to Freundlich isotherm supported by Halsey isotherm model. Langmuir monolayer adsorption capacity (256.41 mg/g) of C-nZVI obtained greater than most adsorbent reported for adsorption of RhB. The mean adsorption free energy, E per molecule evaluated from DKR model was less than 8 KJmol-1 indicating a physisorption mechanism. The kinetic data best fitted to pseudo second-order kinetic model as validated by sum of square error (SSE) statistical model and the mechanism controlled by pore diffusion. The study revealed the great potential of C-nZVI for effective removal of RhB dye. C-nZVI is therefore recommended for civic and industrial effluents treatment