Abstract:In order to make further progress in the field of reducing mercury emissions to the atmosphere it is necessary to develop efficient and economically viable technologies.Low-cost solid sorbents are a candidate technology for mercury capture. However, kinetic models are required to predict the adsorption mechanism and to optimize the design of the process. In this study, several low-cost materials (biomass chars) were evaluated for the removal of gas-phase elemental mercury and kinetic studies were performed to … Show more
“…The uranium qe of 909.091 mg/g was estimated by this model at the equilibrium condition which shows the highest qe by the synthesized adsorbent of SMS-Ph. Table 5 summarized the calculated parameters of pseudo-first- and second-order kinetic models 26,27 .Figure 6( a ) The Langmuir and ( b ) Freundlich adsorption isotherms, ( c ) The pseudo-first- and ( d ) second order kinetic models for uranium adsorption on synthesized MS sample of S′.…”
A novel mesoporous silica with enhanced phosphonic functional groups (PFGs) and without any silane agents was provided by Sol-Gel technique for selective adsorption of U(VI) from aqueous solutions (AqS). The absorbent was synthesized based on the achieving the four best performance characteristics including availability, economically, adsorption efficiency, and selectivity which are undoubtedly defined the usefulness of the adsorbents. The sorption results exhibited the highest uranium adsorption capacity, qe, of 820.7 mg/g at pH ≈ 8 which indicated the adsorbent is the best alternative for uranium adsorption from the nearly neutral solutions such as seawater. The recovery percentages by the adsorbent in the aqueous environments involving other elements such as Mg, Cd, Hg, As, Ca, Na, Ni and the salty environment with high concentration of Cl
−
ions are indicated that the adsorbent presents the acceptable selectivity for uranium adsorption from the AqS such as industrial wastewater. Several activities and factors including removing the silane agents, using sodium metasilicate as an available and low-cost source of silica, and using the Sol-gel method as an unexpansive synthesis technique caused to reduce the synthesis costs from 222.787 EUR/kg for the template method to 60.078 EUR/kg for Sol-gel method which confirm the synthesis of a cost-effective adsorbent.
“…The uranium qe of 909.091 mg/g was estimated by this model at the equilibrium condition which shows the highest qe by the synthesized adsorbent of SMS-Ph. Table 5 summarized the calculated parameters of pseudo-first- and second-order kinetic models 26,27 .Figure 6( a ) The Langmuir and ( b ) Freundlich adsorption isotherms, ( c ) The pseudo-first- and ( d ) second order kinetic models for uranium adsorption on synthesized MS sample of S′.…”
A novel mesoporous silica with enhanced phosphonic functional groups (PFGs) and without any silane agents was provided by Sol-Gel technique for selective adsorption of U(VI) from aqueous solutions (AqS). The absorbent was synthesized based on the achieving the four best performance characteristics including availability, economically, adsorption efficiency, and selectivity which are undoubtedly defined the usefulness of the adsorbents. The sorption results exhibited the highest uranium adsorption capacity, qe, of 820.7 mg/g at pH ≈ 8 which indicated the adsorbent is the best alternative for uranium adsorption from the nearly neutral solutions such as seawater. The recovery percentages by the adsorbent in the aqueous environments involving other elements such as Mg, Cd, Hg, As, Ca, Na, Ni and the salty environment with high concentration of Cl
−
ions are indicated that the adsorbent presents the acceptable selectivity for uranium adsorption from the AqS such as industrial wastewater. Several activities and factors including removing the silane agents, using sodium metasilicate as an available and low-cost source of silica, and using the Sol-gel method as an unexpansive synthesis technique caused to reduce the synthesis costs from 222.787 EUR/kg for the template method to 60.078 EUR/kg for Sol-gel method which confirm the synthesis of a cost-effective adsorbent.
“…Pseudo-first order model 52 . This model is described by the following equation: [53][54][55][56] dq…”
Section: Diffusional Modelsmentioning
confidence: 99%
“…The pseudo-first order equation accurately predicts the initial period of adsorption [57][58][59] and, for that reason, fast Hg 0 adsorption processes can be better adjusted to pseudo-first order kinetics. 53…”
External diffusion is the rate-controlling step in the adsorption of gas phase Hg0 with Au-loaded activated carbon foams (pseudo-first order kinetic model).
“…After attaining the set time, the samples were separated magnetically and the concentrations of Zn(II) and As(III) were determined by AAS. Kinetic models such as pseudo-first order, pseudo-second order, intraparticle diffusion and Elovich kinetic models [19,29,30] were used to determine the process which the experimental data obeyed. Table 1 shows the equation for each model. Similarly, isotherm experiments were studied by using different Zn(II) and As(III) concentrations ranging from 10-100 mg L −1 , at a fixed pH of 5 and 6 respectively.…”
Abstract:In this paper, imine functionalized magnetic nanoparticles (MNP-Maph) were employed to aqueous solutions for the uptake of Zn(II) and As(III). Characterization of the material showed the successful synthesis of this material. Factors affecting the uptake of metal ions in aqueous solution such as change in pH, time, adsorbent dose, adsorbate concentration, and temperature were investigated and optimized to determine the best experimental conditions for the effective adsorption of Zn(II) and As(III) from wastewater samples. The adsorption capacity of MNP-Maph followed similar patterns as that of amine functionalized magnetic nanoparticles (MNP-NH 2 ) for the uptake of both metal ions from aqueous solution when solution pH was varied. Higher pH values favored the uptake of Zn(II) and As(III) by using both adsorbents. Also, increasing the contact time and temperature yielded a higher uptake of Zn(II) and As(III). Both processes can best be described with a pseudo-second order kinetic model, while the Langmuir maximum adsorption capacity (q m ) for Zn(II) increased from 35.83 to 54.53 mg g −1 , and for As(III) from 50.08 to 57.60 mg g −1 .Of note is that the q m of As(III) was higher than that of Zn(II) because of the lower concentration of As(III) in solution compared to that of Zn(II), and thermodynamic parameters indicated that the adsorption processes were heat absorbing and rapid in nature. Experiments to evaluate if the adsorbent could be recycled showed excellent recyclability capacity of MNP-Maph after seven runs. Lastly, application of MNP-Maph for the uptake of Zn(II) and As(III) from municipal wastewater samples showed remarkable sorption performance confirming the potential of imine functionalized magnetic nanoparticles as an excellent adsorbent for the uptake of metal ions from aqueous solutions.
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