Optimization of the removal of the antibiotic ciprofloxacin by composite aerogels based on PVA/agar/maltodextrin
Thi Cam Quyen NgoVan Tan LamHoang Thanh Tu NguyenNgoc Bich HoangThi Tuu TranLe Thi My HanhThi Nhu Dung NguyenLong Giang Bạch
1
Citation
31
Reference
10
Related Paper
Citation Trend
Abstract:
In this study, we used a synthetic aerogel based on PVA/agar/maltodextrin to remove the antibiotic ciprofloxacin (CFX) from aqueous media. Response surface method (RSM) is used to study the relationship between the factors affecting the adsorption process, thereby optimizing the adsorption efficiency, and making decisions on improving the adsorption process better sub. The research results obtained are as follows: pH2, initial CFX concentration 51 mg L −1 , adsorbent dosage 0.16 g L −1 , adsorption time 120 min, and temperature 51.5 °C reached the maximum adsorption capacity. The maximum additive is 38.63 mg g −1 . The experimental data agree with the pseudo-quadratic kinetic model and the Langmuir and Temkin isotherm models. The composite aerogel adsorbent (AE) in this study is a potential candidate for adsorbent to remove antibiotic contamination in aqueous media.Keywords:
Maltodextrin
Langmuir adsorption model
Central composite design
Langmuir adsorption model
Langmuir equation
Cite
Citations (32)
Langmuir adsorption model
Langmuir equation
Liquid phase
Cite
Citations (263)
Langmuir adsorption model
Linearization
Cite
Citations (295)
Standard isotherm equations do not estimate capacity (Qmax) and distribution coefficient (Kd) for complex or non-Langmuir-shaped isotherm plots. In this study, two mycotoxins, that is, aflatoxin B1 (AfB1) and cyclopiazonic acid (CPA), were mixed with kaolinite and a naturally acidic montmorillonite clay (LPHM) at 25 °C, respectively. Isotherm data gave S-type plots. The data were fitted to the models of Langmuir (LM) and multi-Langmuir (MLM); however, these models did not provide a good fit for data that displayed multisite adsorption or multiple plateaus. While a published modification of the Langmuir equation (QKLM), which defines an effective partition coefficient as a function of the surface coverage, was able to fit simple isotherm plots from all categories (H, L, S, C), it did not fit complex or multisite isotherm plots. Importantly, an equation that enables the estimation of Qmax and Kd for both S-shaped and multisite isotherm plots has not yet been reported. Since the LM, MLM, and QKLM did not provide adequate fitting of the data, several modifications of the LM were developed: shifted Langmuir, shifted squared Langmuir, shifted cubed Langmuir, shifted exponential Langmuir, exponential Langmuir, and shifted modified Langmuir. These equations were used to derive information about the adsorption of mycotoxins to clay and to gain insight into the molecular mechanism(s) and site(s) of adsorption. The objectives of this study were to present a series of modified Langmuir equations that can be used to estimate the Qmax and Kd of a specific adsorption site and to relate Qmax to available adsorption area.
Langmuir adsorption model
Cite
Citations (65)
The Langmuir isotherm is a widely used model for analyzing adsorption equilibrium data. This study evaluated the efficiency and accuracy of all four linear forms of the Langmuir isotherm and its non-linear form using 67 experimental data sets selected from the literature. The results showed that only if all four linear forms simultaneously show high accuracy, then the non-linear form also shows high accuracy, and therefore it can be said that the process probably follows the Langmuir isotherm. On the contrary, when at least one of the four linear forms of the Langmuir isotherm has low accuracy, it means that the non-linear form also has low accuracy, and it can be concluded that this process does not follow the Langmuir isotherm. This research suggests that all four linear forms of the Langmuir isotherm should be evaluated simultaneously to conclude whether the studied system follows the Langmuir isotherm or not. In other words, relying on only one of the four linear forms of the Langmuir isotherm to model adsorption and calculate the Langmuir constant and maximum adsorption capacity is an incomplete approach, contrary to the conventional approach.
Langmuir adsorption model
Sorption isotherm
Linear equation
Linear relationship
Cite
Citations (1)
The Langmuir adsorption isotherm provides one of the simplest and most direct methods to quantify an adsorption process. Because isotherm data from protein adsorption studies often appear to be fit well by the Langmuir isotherm model, estimates of protein binding affinity have often been made from its use despite that fact that none of the conditions required for a Langmuir adsorption process may be satisfied for this type of application. The physical events that cause protein adsorption isotherms to often provide a Langmuir-shaped isotherm can be explained as being due to changes in adsorption-induced spreading, reorientation, clustering, and aggregation of the protein on a surface as a function of solution concentration in contrast to being due to a dynamic equilibrium adsorption process, which is required for Langmuir adsorption. Unless the requirements of the Langmuir adsorption process can be confirmed, fitting of the Langmuir model to protein adsorption isotherm data to obtain thermodynamic properties, such as the equilibrium constant for adsorption and adsorption free energy, may provide erroneous values that have little to do with the actual protein adsorption process, and should be avoided. In this article, a detailed analysis of the Langmuir isotherm model is presented along with a quantitative analysis of the level of error that can arise in derived parameters when the Langmuir isotherm is inappropriately applied to characterize a protein adsorption process.
Langmuir adsorption model
Cite
Citations (227)
Langmuir adsorption model
Cite
Citations (27)
A graphical method for evaluating the Langmuir favorable adsorption is proposed in this work. The conditional Langmuir constant (KLN), a new parameter related to the Langmuir equilibrium constant (KL), can be used to predict the shapes of Langmuir favorable adsorption isotherms. On the dimensionless Langmuir isotherm diagram, all the Langmuir favorable adsorptions (0 < RL < 1) are further divided into three subgroups: favorable adsorption, very favorable adsorption, and highly favorable or pseudoirreversible adsorption, with two critical Langmuir constants (KLN1 and KLN2) as the demarcation point. The feasibility of the method is demonstrated by analyzing 14 adsorption systems. The graphical method is effective and intuitional, and can be used for the favorable evaluation of any Langmuir isotherms. This method shows the advantage that the parameter KLN does not depend on the initial adsorbate concentration (co) over RL method.
Langmuir adsorption model
Dimensionless quantity
Cite
Citations (67)
Sorption of several solute-polymer systems can be characterized by a combination of Henry's law sorption and Langmuir adsorption. The sorbate in the Langmuir adsorption is assumed to have different diffusivity compared to the sorbate in Henry's sorption. The concentration distribution and mass uptake of a polymer film subject to a step increase of sorbate at the surface were solved by the Crank-Nicholson method. With a smaller value of diffusivity for the Langmuir adsorbed molecules the normalized concentration distribution and mass uptake increased more slowly than the corresponding sorption without the Langmuir adsorption. The mass uptake after a step increase of the sorbate concentration is proportional to at the beginning stage of sorption. From the parameters of sorption isotherms and the initial slopes of normalized mass uptake vs. plots the diffusivities of both Henry's law sorption and Langmuir adsorption species can be determined.
Langmuir adsorption model
Cite
Citations (0)
Adsorption processes are typically designed with the aid of process simulators. Here, the extended Langmuir model and derivates are frequently used when dealing with type I isotherms (Langmuirian). The extended Langmuir model captures competition effects based on low-coverage Henry selectivity. However, it does not account for adsorbate size effects, where smaller adsorbates can be preferred at a higher pressure. Still, in simulators, the extended Langmuir model is predominantly used over the implicit ideal adsorbed solution theory (IAST), which does predict a size effect. In this work, we define and explore two models, having an explicit form and aimed at introducing an adsorbate size effect. The aim is twofold: First, the extended Langmuir and new model predictions are compared to IAST to demonstrate the adsorbate size effect. Second, all models are tested in a process simulator case study where the performance results as well as execution time are considered. A temperature swing adsorption (TSA) process simulation case study with a 10-component mixture was performed at high loading: the extended Langmuir model shows large recovery differences over the models which do incorporate a size effect. Explicit models can be executed quicker than IAST (FASTIAS), although the manner of implementation in the process simulator is important. The new models may improve the extended Langmuir predictions with respect to (IAST) size effects and also have their limitations.
Langmuir adsorption model
Langmuir Probe
Cite
Citations (7)