Sorption Kinetic Studies Research Articles

The Simulation of Binary Component Sorption Kinetics from the Data of Single Component Sorption

This research is mainly focused on the wastewater treatment using biosorption techniques. The biosorption kinetics of binary sorption of heavy metals by green macro alga Caulerpa lentillifera were studied where such alga was used in the shrimp farm as the nitrogen controller but it grow rapidly so the farmer get rid of its excess amount as waste. The studies of sorption capacity and sorption kinetics of Lead (Pb2+) and Copper (Cu2+) ions in single and binary components were conducted using batch experiments. The new binary sorption kinetic model was developed to predict the experimental results and the calculated outputs from the model were consistent with experimental data.

Sorption thermodynamic and kinetic studies of Lead removal from aqueous solutions by nano Tricalcium phosphate

Nano tricalcium phosphate particles were prepared by a wet method from aqueous solutions and characterized using TEM, XRD, and BET-N2 adsorption measurements. The potential of the synthesized nano tricalcium phosphate particles to remove Pb2+ cations from aqueous solutions was investigated in batch reactor under different experimental condition. The effects of initial concentration, adsorbent dosage, contact time and temperature were studied in batch experiments. The sorption of Pb2+ by nano-TCP increased as the initial concentration of lead ion increased in the medium. Various thermodynamic parameters, such as G°, H° and S° were calculated. Thermodynamics of Pb2+ cation sorption onto nano-TCP system pointed at spontaneous and endothermic nature of the process. The pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models were applied to study the kinetics of the sorption processes. The pseudo-second order kinetic model provided the best correlation (R2 > 0.999) of the used experimental data compared to the pseudo-first order and intraparticle diffusion kinetic models. The maximum Pb2+ adsorbed was found to be 4761.90 mg/g. It was found that the sorption of Pb2+ on nano-TCP was correlated well (R2 = 0.982) with the Langmuir equation as compared to Freundlich and Dubinin–Kaganer–Radushkevich (D-K-R) isotherm equation under the concentration range studied. This study indicated that nano-TCP could be used as an efficient adsorbent for removal of Pb2+ from aqueous solution.

Sorption thermodynamic and kinetic studies of Lead removal from aqueous solutions by nano Tricalcium phosphate

Nano tricalcium phosphate particles were prepared by a wet method from aqueous solutions and characterized using TEM, XRD, and BET-N2 adsorption measurements. The potential of the synthesized nano tricalcium phosphate particles to remove Pb2+ cations from aqueous solutions was investigated in batch reactor under different experimental condition. The effects of initial concentration, adsorbent dosage, contact time and temperature were studied in batch experiments. The sorption of Pb2+ by nano-TCP increased as the initial concentration of lead ion increased in the medium. Various thermodynamic parameters, such as G°, H° and S° were calculated. Thermodynamics of Pb2+ cation sorption onto nano-TCP system pointed at spontaneous and endothermic nature of the process. The pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models were applied to study the kinetics of the sorption processes. The pseudo-second order kinetic model provided the best correlation (R2 > 0.999) of the used experimental data compared to the pseudo-first order and intraparticle diffusion kinetic models. The maximum Pb2+ adsorbed was found to be 4761.90 mg/g. It was found that the sorption of Pb2+ on nano-TCP was correlated well (R2 = 0.982) with the Langmuir equation as compared to Freundlich and Dubinin–Kaganer–Radushkevich (D-K-R) isotherm equation under the concentration range studied. This study indicated that nano-TCP could be used as an efficient adsorbent for removal of Pb2+ from aqueous solution.

A preliminary batch study of sorption kinetics of Cr(VI) ions from aqueous solutions by a magnetic ion exchange (MIEX®) resin and determination of film/pore diffusivity

A magnetic ion exchange resin was tested for the removal of Cr(VI) ions from aqueous solutions in a batch reactor at different resin dosages (0.5–1.5gL−1), pH values (2−10), temperatures (25°C–55°C) and initial concentrations of Cr(VI) (0.11–2.12mmolL−1 or 5.7–110mgL−1). The experimental data were evaluated using kinetic models based on the rate controlling steps relevant to pseudo-first order or pseudo-second order reactions or diffusion through fluid film or pores of the MIEX resin beads. Fast uptake of Cr(VI) ions by MIEX resin facilitates the attainment of equilibrium within 60min. The sorption process is strongly dependent on the initial pH of the solution with maximum occurring at pH4–6. The sorption of Cr(VI) at equilibrium increases with the increase in initial concentration according to the Langmuir isotherm, with a maximum sorption capacity of 93mgg−1 on MIEX resin. Relatively low activation energy of 43kJmol−1 at a high initial concentration of 1mmolL−1 Cr(VI) suggests a mixed chemical-diffusion controlled process, supported by the agreement of the sorption results with the homogeneous particle diffusion model with a film diffusivity of Df=1×10−9m2s−1 and a pore diffusivity of Dp=8×10−13m2s−1.

Isoreticular MOFs functionalized in the pore wall by different organic groups for high-performance removal of uranyl ions

We report the studies of uranyl adsorption on a series of isoreticular Metal–organic frameworks (MOFs) with the same 3D framework decorated by different organic groups in the pore wall. Scanning electron microscope and energy dispersive X-ray spectroscopy indicated that the sorbents were capable of encaging uranium from aqueous solution. Typical adsorption isotherms (Langmuir, Freundlich) studies showed different mechanism of sorption process and kinetic studies described different sorption behavior of the MOF materials, which were due to the different functional groups. Finally, two MOFs were successfully employed to extract U(VI) ions from simulated seawater.

Sorption of acid and basic dyes on radiation-grafted Teflon scrap: equilibrium and kinetic sorption studies

Mutual radiation grafting technique using Co-60 gamma radiation has been used to graft glycidylmethacrylate (GMA) to Teflon scrap. Cationic and anionic adsorbents were prepared from GMA-grafted Teflon scrap (GMA-g-Teflon) by converting epoxy ring into sulphonic acid and triamine groups by doing suitable chemical reactions at elevated temperatures. The converted grafted product was studied for its dye uptake properties from manufactured aqueous dye solution. Uptake of basic dyes namely, Basic red 29 (BR-29) and anionic dye namely, Remazol brilliant blue-1 (RB-1) was investigated. Langmuir and Freundlich adsorption models were used to analyze equilibrium adsorption, while kinetics of adsorption was analyzed using pseudo-first-order, pseudo-second-order models. The equilibrium adsorption of BR-29 and RB-1 was better explained by Langmuir adsorption model. Separation factor (R L ) was found to be in the range 0 < R L < 1, indicating favorable adsorption of basic and acidic dyes. Higher coefficient of determination (or regression) (r 2) and better agreement between q e,cal (calculated) and q e,exp (experimental) values were obtained for pseudo-second-order kinetic model.

NARX Neural Network Modelling of Mushroom Dynamic Vapour Sorption Kinetics

Abstract: This paper is concerned with the study, optimization and control of the moisture sorption kinetics of agricultural products at temperatures typically found in processing and storage. A nonlinear autoregressive with exogenous inputs (NARX) neural network was developed to predict moisture sorption kinetics and consequently equilibrium moisture contents of shiitake mushrooms ( Lentinula edodes (Berk.) Pegler) over a wide range of relative humidity and different temperatures. Sorption kinetic data of mushroom caps was separately generated using a continuous, gravimetric dynamic vapour sorption analyser at temperatures of 25-40 °C over a stepwise variation of relative humidity ranging from 0 to 85%. The predictive power of the neural network was based on physical data, namely relative humidity and temperature. The model was fed with a total of 4500 data points by dividing them into three subsets, namely, 70% of the data was used for training, 15% of the data for testing and 15% of the data for validation, randomly selected from the whole dataset. The NARX neural network was capable of precisely simulating equilibrium moisture contents of mushrooms derived from the dynamic vapour sorption kinetic data throughout the entire range of relative humidity.

Application of soy hull biomass in removal of Cr(VI) from contaminated waters. Kinetic, thermodynamic and continuous sorption studies

Soy hull was evaluated as a new material for Cr(VI) removal from aqueous solutions. Cr(VI) removal was associated to a redox mechanism, in which Cr(VI) was reduced to Cr(III) by the biomass. The redox capacity of soy hull was 1.12mmolg−1. A kinetic model that considers the redox reaction between Cr(VI) and the biomass surface was proposed. The maximum sorption capacity was 7.286mgg−1 at 20°C and pH 1.5. Activation parameters and mean free energies suggest that the sorption process follows a mechanism of chemical sorption. Thermodynamic parameters show that Cr(VI) removal was spontaneous. The isosteric heat of sorption indicated that soy hull has an energetically homogeneous surface. XPS spectra showed that chromium bound on the biomass was Cr(III). These results were confirmed by XANES and EXAFS experiments. EPR spectra showed the presence of Cr(V)-soy hull at short contact time and only a signal corresponding to Cr(III)-soy hull at long contact times. Continuous sorption data were fitted to Thomas and modified dose–response models. The bed depth service time (BDST) model was used to scale-up the continuous sorption experiments.

Removal of Malachite Green, a hazardous dye from aqueous solutions using Avena sativa (oat) hull as a potential adsorbent

Adsorptive potential of an agricultural waste, oat hull for the removal of a dye, Malachite Green from aqueous solutions was investigated. The adsorbent was characterized by FTIR, XRD, SEM, and BET. Batch adsorption experiments were conducted to examine the sorption behavior of MG at different adsorbent particle sizes, solution pH, initial dye concentration, contact time and temperature. Optimum conditions were investigated as adsorbent particle size ~150μm; initial pH, 8.0, contact time, 80min and at 313K. The study of sorption kinetics was found to be more consistent with pseudo second-order model and film diffusion mechanism was interpreted as rate limiting step. The adsorbate–adsorbent interaction as a function of temperature was assessed and the data fitted better in Freundlich model. The adsorption capacity increases with increasing temperature and maximum Langmuir's adsorption capacity was found to be 83mg/g at 313K. Thermodynamic studies indicated that the process of removal of MG was spontaneous in nature. The efficacy of the batch sorption process was further investigated by column experiments. Factors like effect of flow rate and bed depth were examined in column mode. The column sorption data was mathematically treated with bed depth service time (BDST) and Thomas models. The above findings recommend that oat hulls can be successfully used for the decoloration of MG contaminated wastewater.

Synthesis of aminated glycidyl methacrylate grafted rice husk and investigation of its anion‐adsorption properties

ABSTRACTIn this study, we focused on the synthesis, characterization, and adsorption capacity testing of aminated glycidyl methacrylate grafted rice husk (RH‐g‐GMA–Am). Our goal was to obtain a high‐performance surface for the adsorption of various anions. Glycidyl methacrylate grafted rice husk (RH‐g‐GMA) was prepared by the graft copolymerization of glycidyl methacrylate with rice husk; the product was further subjected to an amination reaction. The surface properties, sorption characteristic functional groups, isotherm and kinetic studies, pore diffusion models, and effects of the temperature and pH on the material properties were studied under batch conditions. The IR spectroscopy results show additional surface functional groups for RH‐g‐GMA–Am. The adsorptions of and on RH‐g‐GMA–Am were found to follow pseudo‐second‐order kinetics; this indicated a possible dominant role played by chemisorption. The rate‐limiting step for mass transfer was found to be boundary layer diffusion. Furthermore, the sorption isotherms for and fit the Langmuir model. The amination of RH‐g‐GMA drastically increased the removal efficiency from 3 to 82% and from 6 to 93% for and , respectively. Moreover, RH‐g‐GMA–Am exhibited a better removal efficiency in the pH range of 4–6.5. Regeneration studies revealed that the surface of RH‐g‐GMA–Am could be regenerated repetitively by simple acid washing with an insignificant decrease in the active surface for consecutive adsorptions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43002.

Sorption Thermodynamic and Kinetic Study of Polylactic Acid Fibers with Disperse Dyes in Non-Aqueous Medium

The sorption thermodynamics and kinetics of disperse dyes on polylactic acid (PLA) fibers were investigated. PLA is crucial for a sustainable textile industry. However, the low dye exhaustion limits the textile application of PLA fibers. The basic dyeing parameters have been determined to provide an in-depth understanding of dyeing behavior. The weak sorption affinities were attributed to the weak dye-fiber interaction and favorable chemical potential of dyes in solvent. Enthalpy–entropy compensation effect also played a role in weak sorption. The interplay of dye structure and enthalpy, entropy changes was rationalized using molecular surface area and rotatable bonds. The conformation constraint strategy was proposed to overcome weak sorption affinity problem by lowering the entropy penalty. Temperature dependence of diffusion coefficients was well reproduced using molecular collision based diffusion model. The activation energies of diffusion have been correlated with molecular volumes of dyes.

New approach in modeling Cr(VI) sorption onto biomass from metal binary mixtures solutions

In the last decades Cr(VI) sorption equilibrium and kinetic studies have been carried out using several types of biomasses. However there are few researchers that consider all the simultaneous processes that take place during Cr(VI) sorption (i.e., sorption/reduction of Cr(VI) and simultaneous formation and binding of reduced Cr(III)) when formulating a model that describes the overall sorption process. On the other hand Cr(VI) scarcely exists alone in wastewaters, it is usually found in mixtures with divalent metals. Therefore, the simultaneous removal of Cr(VI) and divalent metals in binary mixtures and the interactive mechanism governing Cr(VI) elimination have gained more and more attention. In the present work, kinetics of Cr(VI) sorption onto exhausted coffee from Cr(VI)–Cu(II) binary mixtures has been studied in a stirred batch reactor. A model including Cr(VI) sorption and reduction, Cr(III) sorption and the effect of the presence of Cu(II) in these processes has been developed and validated. This study constitutes an important advance in modeling Cr(VI) sorption kinetics especially when chromium sorption is in part based on the sorbent capacity of reducing hexavalent chromium and a metal cation is present in the binary mixture.

The antimicrobial efficiency of silver activated sorbents

This study is focused on the surface modifications of the materials that are used for antimicrobial water treatment. Sorbents of different origin were activated by Ag+-ions. The selection of the most appropriate materials and the most effective activation agents was done according to the results of the sorption and desorption kinetic studies. Sorption capacities of selected sorbents: granulated activated carbon (GAC), zeolite (Z), and titanium dioxide (T), activated by Ag+-ions were following: 42.06, 13.51 and 17.53mg/g, respectively. The antimicrobial activity of Ag/Z, Ag/GAC and Ag/T sorbents were tested against Gram-negative bacteria E. coli, Gram-positive bacteria S. aureus and yeast C. albicans. After 15min of exposure period, the highest cell removal was obtained using Ag/Z against S. aureus and E. coli, 98.8 and 93.5%, respectively. Yeast cell inactivation was unsatisfactory for all three activated sorbents. The antimicrobial pathway of the activated sorbents has been examined by two separate tests – Ag+-ions desorbed from the activated surface to the aqueous phase and microbial cell removal caused by the Ag+-ions from the solid phase (activated surface sites). The results indicated that disinfection process significantly depended on the microbial-activated sites interactions on the modified surface. The chemical state of the activating agent had crucial impact to the inhibition rate. The characterization of the native and modified sorbents was performed by X-ray diffraction technique, X-ray photoelectron spectroscopy and scanning electron microscope. The concentration of adsorbed and released ions was determined by inductively coupled plasma optical emission spectroscopy and mass spectrometry. The antimicrobial efficiency of activated sorbents was related not only to the concentration of the activating agent, but moreover on the surface characteristics of the material, which affects the distribution and the accessibility of the activating agent.

Kinetic Uptake Studies of Powdered Materials in Solution.

Challenges exist for the study of time dependent sorption processes for heterogeneous systems, especially in the case of dispersed nanomaterials in solvents or solutions because they are not well suited to conventional batch kinetic experiments. In this study, a comparison of batch versus a one-pot setup in two variable configurations was evaluated for the study of uptake kinetics in heterogeneous (solid/solution) systems: (i) conventional batch method; (ii) one-pot system with dispersed adsorbent in solution with a semi-permeable barrier (filter paper or dialysis tubing) for in situ sampling; and (iii) one-pot system with an adsorbent confined in a semi-permeable barrier (dialysis tubing or filter paper barrier) with ex situ sampling. The sorbent systems evaluated herein include several cyclodextrin-based polyurethane materials with two types of phenolic dyes: p-nitrophenol and phenolphthalein. The one-pot kinetics method with in situ (Method ii) or ex situ (Method iii) sampling described herein offers significant advantages for the study of heterogeneous sorption kinetics of highly dispersed sorbent materials with particles sizes across a range of dimensions from the micron to nanometer scale. The method described herein will contribute positively to the development of advanced studies for heterogeneous sorption processes where an assessment of the relative uptake properties is required at different experimental conditions. The results of this study will be advantageous for the study of nanomaterials with significant benefits over batch kinetic studies for a wide range of heterogeneous sorption processes.

Application of green seaweed biomass for MoVI sorption from contaminated waters. Kinetic, thermodynamic and continuous sorption studies

Spongomorpha pacifica biomass was evaluated as a new sorbent for MoVI removal from aqueous solution. The maximum sorption capacity was found to be 1.28×106±1×104mgkg−1 at 20°C and pH 2.0. Sorption kinetics and equilibrium studies followed pseudo-first order and Langmuir adsorption isotherm models, respectively. FTIR analysis revealed that carboxyl and hydroxyl groups were mainly responsible for the sorption of MoVI. SEM images show that morphological changes occur at the biomass surface after MoVI sorption. Activation parameters and mean free energies obtained with Dubinin–Radushkevich isotherm model demonstrate that the mechanism of sorption process was chemical sorption. Thermodynamic parameters demonstrate that the sorption process was spontaneous, endothermic and the driven force was entropic. The isosteric heat of sorption decreases with surface loading, indicating that S.pacifica has an energetically non-homogeneous surface. Experimental breakthrough curves were simulated by Thomas and modified dose–response models. The bed depth service time (BDST) model was employed to scale-up the continuous sorption experiments. The critical bed depth, Z0 was determined to be 1.7cm. S.pacifica biomass showed to be a good sorbent for MoVI and it can be used in continuous treatment of effluent polluted with molybdate ions.

Sorption Kinetics Study of Monocrotophos (MCP) Pesticide in Unsterilized Soil

Sorption Kinetics Study of Monocrotophos (MCP) Pesticide in Unsterilized Soil

Comparative studies of sorption of phenolic compounds onto carbon-encapsulated iron nanoparticles, carbon nanotubes and activated carbon

Abstract The systematic comparative adsorption studies of three phenolic compounds (phenol, 2-chlorophenol and 4-chlorophenol) from aqueous solutions onto three types of carbon sorbents are presented. The equilibrium sorption studies along with sorption kinetics were investigated onto carbon-encapsulated iron nanoparticles, multi-wall carbon nanotubes and granulated activated carbon. These carbon sorbents have significantly different morphological and textural properties. Their surface area varied between 36 and 1187 m2 g−1. The highest adsorption capacity (280–550 mg/g) was found for activated carbon. The uptakes of adsorbates onto carbon nanotubes and carbon-encapsulated iron nanoparticles were substantially lower, i.e. 24–87 mg/g and 5–11 mg/g, respectively. The performed sorption kinetics studies revealed that the sorption kinetic rates for carbon nanotubes and carbon-encapsulated iron nanoparticles are 2–3 orders of magnitude larger (2–10 × 10−2 g mg−1 min−1) in comparison to activated carbon (1.9–4.5 × 10−4 g mg−1 min−1). The sorption performance and sorption kinetics were systematically discussed in the frames of morphology and textural properties of sorbents and the properties of adsorbates. Additionally, it was demonstrated that the sorption capacity of carbon nanotubes and carbon-encapsulated iron nanoparticles can be largely improved by the post-synthesis activation process. In this case the adsorption capacities increased even 2–7 times. The spent sorbents were regenerated in acetone. It was also found that carbon nanotubes and carbon-encapsulated iron nanoparticles retain up to 65% of their pristine adsorption performance, whilst the sorption capacity of activated carbon is reduced of 80%.

Influence of solvent exchange time on mixed matrix membrane separation performance for CO2/N2 and a kinetic sorption study

Carbon dioxide (CO2) is the largest contributor of greenhouse gas emissions. Mixed matrix membranes (MMMs) have recently received attention as an attractive candidate for membrane-based separation, for which MMMs can serve as an alternative to conventional polymeric and inorganic membranes. In this work, MMMs were developed using a cellulose acetate polymer with multi-walled carbon nanotubes. Vacuum drying and solvent-exchange drying methods were compared with different solvent exchange times (ethanol and hexane) based on the MMM morphologies and separation performances. The sorption of CO2 and the diffusion and solubility coefficients of the MMMs that were synthesized using the two drying methods mentioned above were determined kinetically. The separation results supported the effectiveness of the newly proposed solvent-exchange technique, where the MMMs that were treated with ethanol for 4h followed by n-hexane for 1h (M6) had greater mechanical strength and a better CO2/nitrogen (N2) separation performance at 40.17. Additionally, the kinetic results indicated that the solubility coefficient directly influenced the CO2 permeance, with the highest value of 198.352×1011cm3(STP)/cm4cmHg observed for the M6 membrane sample (4h ethanol followed by 1h n-hexane).

Enhanced carbon capture biosorption through process manipulation

The feasibility of manipulating operating parameters, i.e. Food-to-microorganisms (F/M) ratio, SRT, and residual DO, to enhance biosorption performance was investigated. It was observed that lower F/M and longer SRT resulted in sludges which captured carbon mainly through carbon storage. Surface sorption, however, was the dominant mechanism for sludges grown under the higher DO condition. Generally, biosorption was optimal at pH 7. Sorption kinetic studies revealed that sludge cultivated under the low F/M ratio of 0.15 (Sludge S1) showed the best overall biosorption performance. Determination of calorific value revealed that Sludge S1 was able to capture energy as much as 0.9kJ/g SS within 15min contact time. About 66.3% of the overall biosorption capacity was attributed to carbon storage. Sludge S1 was able to accumulate organic substrate and stored this as polyhydroxyalkanoates (PHA). Culture-independent microbial community analysis through DGGE revealed the presence of strains capable of PHA-accumulation, e.g. Rhodobacter sp., and Thauera sp. While different dominating mechanisms resulted from different cultivation conditions, the best biosorption performance was significantly contributed by carbon storage activity.

SEM and EDAX Study of Pretreated Rice Husk for the Sorption of Cu(II) from Wastewater

The morphological characteristics as well as important physical and chemical characteristics rice husks were evaluated by different techniques to analyze the suitability of rice husk to adsorb metal ions from water and wastewater. The raw rice husk (RRH), sodium carbonate treated rice husk (NCRH) and metal adsorbed rice husk were analyzed by SEM-EDAX study. Batch sorption kinetics studies were also conducted for Cu (II) to find the corresponding equilibrium time and the percentage removal for each of the experiment in the sorption process. The results of material characteristics and morphological aspects pointed out some properties that can make the sorption processes possible. The copper removal was observed in the range of 90 to 97 % depending upon the other physicochemical parameters of the sorption experiment. The highly efficient low cost and the rapid uptake by the proposed material indicated that it could be an excellent alternative for the removal heavy metal by sorption process.