The adsorption—desorption experiment utilizing nitrogen gas N 2 was carried out at 77 K. The N 2 isotherm is used to identify the specific surface area executing the multipoint method of BET. It should be mentioned that the specific surface areas and pore volume of Cu OH 2 -NWs-PVA-AC were appreciably greater than similar adsorbent products which were reported by previous researchers in the literature.
The high specific surface area of this adsorbent can be attributed to enhancing in inter-particle of pore volume The typical isotherm with H3 hysteresis represents the mesoporous materials with a wide size distribution which has an average width and volume of its pores determining 0. S3 , Supplementary Information. As illustrated in Fig. The total survey spectra of the Nano-composite before and after adsorption of MB dye was delineated in Fig.
S5 Supplementary Information. The B. The O 1s spectra indicate the presence carbons containing species with oxygen functional groups in the Nano-composite. As shown in Fig.
Likewise, the B. S6 Supplementary Information. The O 1s spectra indicate important functional groups in the MB dye and the other C—O functional groups in the Nano-composite. S7 Supplementary Information. The results are in accordance with the powder XRD analysis Fig. S7 b, which shows that changes in the patterns of XPS peaks with a slight change in the B. Adsorption mechanism is a significant assignment to explore in the present study of sorption processes.
The earlier reports revealed that some possible interactions that occurred between the MB and Cu OH 2 -NWs-PVA-AC are accountable for the adsorption, like electrostatic interactions, hydrogen bonds, and electron donor—acceptor interactions. In addition, the MB dye molecule thickness, depth, and width are equal to 1. Besides, the adsorption process also dependent on the adsorbent functional groups. These surface functional group on top plays a significant role in the adsorption capacity and the elimination mechanism of the MB dye.
From the activated carbon the key functional groups of carboxyl and hydroxyl are lending to adsorb cationic MB by electrostatic interaction. The C—C bond could make the potentially stableadsorption system to avoid desorption of MB dye As evidenced by XPS Figs. The influence of solution p H is a significant control parameter in the adsorption process. MB being a cationic dye, it has a positively charged species and p H is 7—8.
The present study shows that a gradual raise in the p H from 2 to 10 results increase in the adsorption capacity. The surface of adsorbent becomes positively charged at lower p H due to protonation of hydroxyl ions present in PVA and Cu OH 2 ; thereby, cationic MB dye leads to a strong electrostatic repulsion effect between adsorbent and MB dye Thus, it was observed that the reaction at higher p H can render a strong electrostatic attraction against MB.
Similar results were attained and disclosed by other researchers 37 , Effect of p H. The adsorption investigation was performed for various contact time intervals 0—60 min. Figure 7 showed the adsorption of MB was enhanced when the contact time was increased to 10 min. In addition, it was observed that an increase in contact time did not show any significant increment in the adsorption processes. At the beginning stage, the rate of adsorption was extremely rapid; after that, the adsorption process was almost moderate.
In the initial stages, adsorption is faster because of the existence of an extensive number of binding sites for adsorption. At the ending stage, the adsorption processes found very slow because of the saturation of the binding sites which leads to occur the equilibrium 39 , This phenomenon leads to the adsorption of the huge contaminant within a limited time. In this experiment, the adsorption equilibrium was acquired within 10 min.
Effect of dye concentration and contact time on MB. The adsorption experiment was carried out in batch mode, and the results revealed that the initial concentration of MB dye solution plays a crucial role as a driving parameter to overcome the mass transit between the two different phases. It was observed that the solution with lower concentrations of MB molecule contains a number of sites, which makes adsorption easier. From this study it was revealed the adsorption rate was higher at the initial stage.
Nevertheless, it was noticed the solution contains more MB dye concentration that affects the adsorption capacity due to the saturation of the sites convenient for sorption on the adsorbent.
Figure 8 shows that the adsorption kinetics at various initial MB concentrations. From these models, we can evaluate the kinetic data for MB adsorption and find a reliable model for expressing the experimental q e value.
The kinetic equations are shown below:. Conditions: As shown in Fig. The kinetic parameters data was shown in Table 2. Additionally, PSO model calculated equilibrium adsorption capacity values q ecal also in concurrence with the experimental q e value, as compared with the other kinetic models.
Weber and Morris intra-particle diffusion model also studied. From Fig. Mostly, at higher correlation coefficient R 2 exhibits a better fit for the model. Table 2 shows that the statistical study for the adsorption kinetics and this analysis was carried out using some predictive test tools viz.
Adsorption isotherms are authentically necessary for fact-finding the adsorption properties of adsorbents. To determine the temperature effect on MB dye adsorption, the adsorption experiment was carried out at different temperatures , and K.
The adsorption isotherms constant was predicted using the experimental data obtained from nonlinear regression through excel-solver software. Adsorption isotherm non-linear fitting results are illustrated in Fig. From the Fig. Generally, the two-parameter equation models are Langmuir Freundlich, and Temkin was extensively used than the three-parameter equation models of Redlich—Peterson and Langmuir—Freundlich owing to the troublesomeness of calculating three parameters isotherm model. But, a three-parameter adsorption isotherms models can usually deliver a better fit of the isotherm data than two-parameter models The adsorption isotherm data from Fig.
The predictable model parameters with the correlation coefficient R 2 and standard error S. From the five adsorption isotherm model equations were establish to be statistically notable results. The Langmuir, Freundlich, and Tempkin equations have fitted the data nearly as well as the three-parameter equations. The Langmuir equation could fine fitting with the adsorption data. In both the Langmuir—Freundlich and Langmuir equations, q m is the amount of the maximum adsorption capacity is The fitting of the adsorption isotherm models are more mathematically meaningful and do not deliver any indication for the definite adsorption mechanisms, the Langmuir—Freundlich and Langmuir models constant can be used for calculating the dimensionless separation factor, which is suggesting of the isotherm shape that predicting the adsorption system favorability.
From the Langmuir isotherm, it was found that the monolayer maximum sorption capacity q m decreased from Generally, the Freundlich model constant n value was between 0 and 10, the adsorption process is favorable for chemisorption. The dimensionless equilibrium constant R L also determined for the Langmuir and Langmuir—Freundlich models.
This separation factor R L is expressed by the following equation: Nonlinear regression was used based on its merging test to reduce the error distribution between the experimental data and the estimated adsorption isotherms. The data interpretation determines through excel-solver software, standard error S. The result of the present investigation confirms that at the lowest value of S. This confirms that the Langmuir—Freundlich and Langmuir isotherm models establish the optimal fit to the experimental values.
The standard Gibbs free energy was expressed at different temperatures according to the following Eqs. The data is tabulated in Table 5. The results for MB removal reported in the literature are summarized in Table 6. International Hazard. National Hazard. Hazard to Lanthanides. Not logged in [ Login ].
Back to:. Printable Version. I decanted the solution and let the wet precipitate dry. Login Register. Additional recommended knowledge. Topics A-Z. All topics. To top. About chemeurope. Colorimetry-Software Day Free Trial. Your browser is not current. Microsoft Internet Explorer 6. Your browser does not support JavaScript. To use all the functions on Chemie. DE please activate JavaScript. IUPAC name. CAS number. Molecular formula. Procedure: Place a stir bar in the beaker containing the hydroxide and stir on a stir plate.
Slowly add 1M HCl until solution becomes transparent. If the reaction goes slowly, use the 6M HCl. Repeat with the magnesium hydroxide and the iron hydroxide.. Safety: Hydrochloric acid is corrosive and may cause burns.
Disposal: Solutions of copper and iron chloride should be disposed of in an appropriate waste container.
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