“…The evaluation is based on the application of three kinetic adsorption linearized models: pseudo-first-order (Lagergren model), pseudo-second-order (Ho model), and intraparticle diffusion (Weber-Morris model), which are represented by Eqs. ( 11 ), ( 12 ), and ( 13 ), respectively 25 . where q t and q e are the adsorption capacity (mg/g) at time t (min) and at equilibrium, respectively; K 1 and K 2 are pseudo-first order (min −1 ) and pseudo-second order (g/mg min) adsorption rate constants, respectively; K P is the constant of the intraparticle diffusion rate (mg/g min 0.5 ); and C is the constant of the intraparticle diffusion.…”
Batch adsorption treatment using Iraqi bentonite as a natural adsorbent was adopted in this study to decontaminate actual 137Cs radioactive wastewater from the Al-Tuwaitha Nuclear Research Center, located south of Baghdad. The bentonite characterization was applied before and after treatment, using chemical compositions analyses, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area analysis and Fourier-transform infrared spectroscopy (FT-IR). The batch adsorption mode was applied with the initial radioactivity concentration (1440.5 Bq/L), solid/liquid ratio (1 g/L), pH (6–8), contact time (1.5 h), and temperature (298°K). The adsorption experiments showed a decontamination removal efficiency of about 95.66% of 137Cs. A Freundlich adsorption isotherm model was approved for the adsorption of 137Cs, with a coefficient of determination R2 = 0.998. A pseudo-second-order model fitted well with the adsorption of 137Cs, with R2 = 0.983. The positive value of ΔH° in the thermodynamic results indicated that the adsorption process was endothermic physisorption (ΔH° = 15.01 kJ mol−1), spontaneous and favorable (ΔG° = −7.66 kJ mol−1 K−1), with a very low degree of disorder (ΔS° = 0.076 kJ mol−1 K−1).
“…The evaluation is based on the application of three kinetic adsorption linearized models: pseudo-first-order (Lagergren model), pseudo-second-order (Ho model), and intraparticle diffusion (Weber-Morris model), which are represented by Eqs. ( 11 ), ( 12 ), and ( 13 ), respectively 25 . where q t and q e are the adsorption capacity (mg/g) at time t (min) and at equilibrium, respectively; K 1 and K 2 are pseudo-first order (min −1 ) and pseudo-second order (g/mg min) adsorption rate constants, respectively; K P is the constant of the intraparticle diffusion rate (mg/g min 0.5 ); and C is the constant of the intraparticle diffusion.…”
Batch adsorption treatment using Iraqi bentonite as a natural adsorbent was adopted in this study to decontaminate actual 137Cs radioactive wastewater from the Al-Tuwaitha Nuclear Research Center, located south of Baghdad. The bentonite characterization was applied before and after treatment, using chemical compositions analyses, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area analysis and Fourier-transform infrared spectroscopy (FT-IR). The batch adsorption mode was applied with the initial radioactivity concentration (1440.5 Bq/L), solid/liquid ratio (1 g/L), pH (6–8), contact time (1.5 h), and temperature (298°K). The adsorption experiments showed a decontamination removal efficiency of about 95.66% of 137Cs. A Freundlich adsorption isotherm model was approved for the adsorption of 137Cs, with a coefficient of determination R2 = 0.998. A pseudo-second-order model fitted well with the adsorption of 137Cs, with R2 = 0.983. The positive value of ΔH° in the thermodynamic results indicated that the adsorption process was endothermic physisorption (ΔH° = 15.01 kJ mol−1), spontaneous and favorable (ΔG° = −7.66 kJ mol−1 K−1), with a very low degree of disorder (ΔS° = 0.076 kJ mol−1 K−1).
“…8 B. Given that 4-nitroaniline regression coefficients are so high R 2 = 0.9949, the pseudo 2nd order hypothesis for the adsorption mechanism process appears to be well-supported 22 . Figure 8 ( A ) Pseudo 1st and ( B ) 2nd order kinetics for the 4-Nitroaniline adsorption on MCM-48.…”
Section: Resultsmentioning
confidence: 88%
“…These material properties are high thermal stability, specific pore volume up to 1.2 cm 3 g −1 , surface areas (1000–1500 m 2 g −1 ), a narrow pore-size distribution, and ‘‘non-cytotoxic’’ properties 21 . Mesoporous silica-based materials, including MCM-48, have been developed as efficient catalyst carriers, adsorbents, and cutting-edge drug delivery systems 22 . This is due to their very considerable thermal stabilities, porous morphologies, huge surface areas, and highly reactive surfaces for the presence of the silanol groups 23 , 24 .…”
In this work, the MCM-48 mesoporous material was prepared and characterized to apply it as an active adsorbent for the adsorption of 4-nitroaniline (4-Nitrobenzenamine) from wastewater. The MCM-48 characterizations were specified by implementing various techniques such as; scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area, pore size distribution (PSD), and Fourier transform infrared (FTIR). The batch adsorption results showed that the MCM-48 was very active for the 4-nitroaniline adsorption from wastewater. The adsorption equilibrium results were analyzed by applying isotherms like Langmuir, Freundlich, and Temkin. The maximum experimental uptake according to type I Langmuir adsorption was found to be 90 mg g−1 approximately. The Langmuir model with determination coefficient R2 = 0.9965 is superior than the Freundlich model R2 = 0.99628 and Temkin model R2 = 0.9834. The kinetic adsorption was investigated according to pseudo 1st order, pseudo 2nd order, and Intraparticle diffusion model. The kinetic results demonstrated that the regression coefficients are so high R2 = 0.9949, that mean the pseudo 2nd order hypothesis for the adsorption mechanism process appears to be well-supported. The findings of adsorption isotherms and kinetics studies indicate the adsorption mechanism is a chemisorption and physical adsorption process.
“…The adsorption rate is an important index to evaluate the adsorption performance, which is generally studied by adsorption kinetics. Adsorption kinetics can reveal the diffusion mechanism, adsorption steps, and controlling factors of adsorption [61]. At the same time, it can also reveal the time when the adsorbent reaches the adsorption equilibrium.…”
In order to deal with the increasingly serious pollution of graphene oxide (GO) to the environment. In this paper, the use of red sandstone to treat GO-contaminated aqueous solution is proposed for the first time, and the adsorption capacity and adsorption mechanism of red sandstone to GO are discussed. The controlled variable method was used to explore the optimal pH, concentration, and quality of red sandstone for GO aqueous solution. The adsorption isotherm, thermodynamics, and adsorption kinetics were fitted. Adsorption characterization tests were performed using XRD, AFM, XPS, FT-IR, SAP, TEM, SAP, laser particle size analyzer, and SEM. The results show that when
T
=
303
K
, the optimum adsorption condition of red sandstone for GO is
pH
=
4
, the mass of the adsorbent is 40 mg, and when the concentration of GO is 80 mg/L, the adsorption capacity is 90 mg/g. The adsorption isotherm model fits the Langmuir model. The adsorption thermodynamic experiments and fitting results show that the reaction is endothermic. XRD and FT-IR tests showed that CaCO3 in red sandstone was involved in the adsorption of GO. SEM, TEM, and AFM microscopic results showed that GO was adsorbed on the surface of red sandstone particles. The XPS test showed that Ca2+ in red sandstone and C=O bond in GO undergo ionic or coordination reaction. The adsorption kinetics fit a pseudo-second-order kinetic model. This study will provide some references for the removal of GO in the environment and the interaction mechanism with natural minerals.
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