Papers by Keyword: Isotherm

Abstract: The objective of this work is the valorization of certain local clays by their use in the treatment of waste water. For this, we have improved the surface properties of a natural Algerian Clay from the west of Algeria from the deposit of ghousel (Maghnia). The treatments carried out are the following: physical and chemical. The prepared material (calcined and activated) was characterized by infrared spectroscopy, measurement of the cation exchange capacity, specific surface and by measuring the pH (pzc). Then, the clay used is applied to the adsorption of an industrial dye (yellow bemacid) in aqueous solution. The quantitative analysis of the dye was followed by UV-Visible spectrophotometer, this analysis allows to determine the best conditions that favor the adsorption such as contact time, adsorbate concentration, adsorbent mass, solution pH and temperature.

Abstract: The process of adsorption treatment of effluents from ammonium ions is considered as an integrated two-stage process consisting of the stage of adsorption of contaminants by natural sorbents in the apparatus with a stirrer and the liquid separation stage and solid phases. Mathematical models of ammonium ions adsorption from effluents by natural dispersed sorbents are proposed, based on the assumption that the process is described by Langmuir and Friendlich isotherms. The values of ion exchange equilibrium constants for different types of natural sorbents have been established by identifying experimental data for theoretical dependences. The obtained constants can be used to calculate the average concentration of ammonium ions in the solution and in the grain of the sorbent in the process of integrated adsorption process. Based on the analysis of the research results, the optimum method of the spent sorbent separation was selected - separation of the suspension of purified ammonium-containing effluents - spent sorbent under the action of gravity. Indicators of optimization of complex process of sewage treatment from ammonium ions are offered.

Abstract: Adsorption is a unit operation of separating solute from solution using another solid material. Modelling of experimental adsorption isotherm data is an essential way for predicting the mechanisms of adsorption, which will lead to an improvement in adsorption science. The main aim of the present work is to analyse various forms of Langmuir isotherm for adsorption of copper from its aqueous solution using cucumber peel from the batch experimental data. The linearized and nonlinearized isotherm models were compared and discussed. In order to determine the best fit isotherm model, the determination coefficient (R²) and sum of square of error (SSE) for each model were used. The modelling results showed that nonlinear Langmuir model could fit the data better than other forms, with relatively higher R² values (0.9879) and smaller SSE (0.013). The linear forms of Langmuir model had the maximum adsorption capacities deviated from the experimental data. The maximum adsorption achieved was 66.61 mg/g after validation with experimental results.

Abstract: Chemically activated carbon of BVT fruit shell was investigated for its potential adsorption functionalities to remove As (V) from surface water in a batch system. The AC showed maximum removal efficiency of approximately 75% depicting Q_max of 0.00018mg/g at an initial sorbate concentration of 0.016mg/L, a contact time of 26min, and a carbon dosage of 1g. The sorption isotherm studies revealed a better fit for Langmuir isotherm. Hence, a homogeneous monolayer surface adsorption process has taken place.

Abstract: In this study, the effectiveness of novel nanocomposite-coated filters consisting of biochar (BC) functionalized with sodium alginate (SA) and poly (vinyl alcohol) (PVA) was investigated for methylene (MB) blue removal. The filters were fabricated via a dip-coating method and SEM and FTIR spectroscopy confirmed the successful coating of the filters. The impact of the nanocomposite formulation and the operating parameters (initial pH and MB concentration) on the performance of the coated filters were studied. A nanocomposite composition consisting of 1.0 wt.% SA, 2.0 wt.% PVA, and 1000 ppm BC were found to be optimum, reaching as high as 96.51% MB removal. The fabricated filters were determined to be robust over a wide range of pH and initial MB concentrations. The Sips isotherm model proved to be the best-fit model for MB adsorption, where chemisorption dominates at low MB concentrations, while physisorption dominates at high MB concentrations. The filters have a maximum sorption capacity of 54.5198 mg g^-1 and showed good reusability. Overall, our synthesized SA/PVA/BC-coated filters can be used to effectively remove dyes in wastewater over a wide range of operating conditions.

Abstract: The removal of mercury from the waterbody remains a severe challenge in ensuring environmental safety due to its highly toxic and non-biodegradable properties. Adsorption is an evidently effective method for heavy metal removal in water. This research aims to study the mercury (II) ion adsorption behavior in aqueous solution onto extruded natural bentonite in monolithic structure, bentonite-based monolith (BBM) adsorbent. BBM was characterized by XRD, BET, and SEM, the results verify BBM could improve adsorption performance assumed on its structure. Adsorption efficiency, isotherm model, and adsorption kinetic were investigated. Experiments were performed in a lab-scale batch reactor with mercury solution concentration varied from 1 to 5 mg/L. The maximum adsorption efficiency discovered to be 63,9%. The experimental data fitted well to Langmuir isotherm (non-linear) and kinetic model pseudo first order (non-linear), revealing the maximum monolayer capacity (Q_o) of BBM to be 0,187 mg/g with Langmuir constants K_L and a_L are 0,215 L/g dan 1,151 L/mg respectively. These value confirms that BBM adsorbent encompasses tremendous potential for mercury (II) ion removal in a solution.

Abstract: This study discusses the development of Indonesian natural zeolite and agricultural waste i.e bagasse ash and rice husk ash as natural adsorbents. These materials were used as an adsorbent for methyl orange and methylene blue adsorption for isotherm and kinetic study. Adsorption kinetic models for methyl orange and methylene blue with all adsorbents were a pseudo-second-order except methyl orange adsorption with bagasse ash adsorbent (MA) that followed pseudo-first-order. Isotherm models for all adsorption experiments were Langmuir type except methyl orange adsorption using rice husk adsorbent (MS) that followed Freundlich type.

Abstract: The adsorption behavior of methanol vapor onto three commercial silica gels named SG-1, SG-2 and SG-3 were investigated in this paper. The experimental results showed that SG-1 has the rich microporous, and the larger surface area and microporous volume than SG-2 and SG-3. The equilibrium adsorption data showed that the adsorption capacities of SG-1 was superior to SG-2 and SG-3 for lower concentration of methanol (<150 g/m3). However, SG-2 had higher adsorption capacities than SG-1 and SG-3 for higher concentration of methanol resulting from the condensation in mesopore channels. Three kinds of adsorption equilibrium equations including Langmuir equation, Freundlich equation and Dubinin-Astakov (D-A) equation were used to fit the methanol vapor adsorption isotherms. The results indicated that the experimental data can be well-fitted by D-A equation.

Abstract: The aim of this study is to characterize Bayah natural zeolites and tested for ammonium capture. Characterization of Bayah natural zeolites were performed by X-ray diffraction (XRD), scanning electron microscope (SEM), and nitrogen physisorption. The natural zeolites were identified as mordenite and clinoptilolite. Non-zeolitic phase appeared on the XRD pattern was quartz. The morphology of clinoptilolite and mordenite were observed as platy and needle shape in the SEM images, respectively. Major cations were K⁺ and Ca²⁺ which were determined by energy dispersive X-ray. Nitrogen isotherm physisorption suggested that the natural zeolites was typical of type IV isotherm. Pore size distribution were determined using Barrett, Joyner, and Halenda model with mesopore size 3-5 nm. Ammonium exchange on Bayah natural zeolites were conducted in a batch experiment by varying the particle sizes, time and mass loading. Non-linear least squared method was applied to fit the experimental data with various kinetic and isotherm models. The kinetic data was well fitted with the Elovich equation with error 1.6 x 10^-4. Isotherm adsorption of ammonium followed Langmuir-Vageler with error 4 x 10^-2.

Abstract: The mangosteen rind has O‒H, C=C aromatics, and ethers functional groups, its performance for Au adsorption become an interesting research to both environment and economic purpose. In this study, waste mangosteen rind as eco-friendly adsorbent had been used for Au(III) adsorption. Initiate by maceration for pre-treatment of biosorbent, the mangosteen rind’s perfomance was revealed. Crystalline structure of mangosteen rind was analyzed by X-ray diffraction, while after interaction with Au(III) ions gave three characteristic peaks indicated Au(III) reduction into Au(0). The adsorption followed isotherm Langmuir model and afforded spontaneous reaction that evidenced by enhancement of ∆G° by increasing of temperature (–1.7 at 30 °C to –8.4 at 60 °C). The value of ∆H° and ∆S° were 71.1 kJ mol^–1 and 238.5 J mol^–1 K^–1, respectively.