Modeling Of Breakthrough Curves Research Articles

Fixed-Bed Adsorption of Ranitidine Hydrochloride Onto Microwave Assisted—Activated Aegle marmelos Correa Fruit Shell: Statistical Optimization and Breakthrough Modelling

In this study, the feasibility of using microwave-irradiated Aegle marmelos Correa fruit shell was investigated in a fixed-bed column towards sorptive removal of ranitidine hydrochloride (RH) from simulated aqueous solution. Characterizations of adsorbent such as SEM, point of zero charge, BET surface area, Boehm surface functional groups, thermal and elemental analysis were carried out. Box–Behnken response surface methodology was utilized to optimize the process parameters such as influent flow rate (2.5–4.5 ml min−1), initial RH concentration (100–200 mg l−1), adsorbent particle size (0.082–0.20 mm), and fixed-bed height (5–10 cm). The highest fixed-bed adsorptive removal of RH at optimum conditions viz. bed height 9.19 cm, initial RH concentration 184.94 mg l−1, flow rate 3.76 ml min−1 and adsorbent particle size 0.2 mm was estimated to be 72.86%. Fixed-bed adsorption experiments were carried out at optimum conditions obtained at different bed heights, and the data obtained were fitted into different kinetic models to predict the applicable breakthrough curve model. Dose–response model was observed to be the best suited model for mathematical description of RH removal in fixed-bed column studies over other selected models.

Phosphate adsorption from aqueous solution by Laminaria japonica‐derived biochar‐calcium alginate beads in a fixed‐bed column: Experiments and prediction of breakthrough curves

Phosphate adsorption onto Laminaria japonica‐derived biochar (LB)‐calcium alginate beads (CAB) under a continuous flow fixed‐bed column condition was investigated by varying three operating parameters including the bed height, initial phosphate concentration, and flow rate. Experimental results confirmed that the breakthrough time and exhaustion time decreased with decreasing bed height and increasing initial phosphate concentration and flow rate. The relationship between the adsorption capacity of LB‐CAB and the varied parameters was assessed and predicted using three different theoretical breakthrough curve models: the Adams–Bohart, Thomas, and Yoon–Nelson models. Among them, the breakthrough curves were successfully simulated with the Yoon–Nelson model for all operating parameters with the highest R2 and the lowest error function values. Finally, a simple pot experiment for the growth of Lactuca sativa revealed that the addition of phosphate adsorbed LB‐CAB (10% wt/wt) offers potential for use as an additive to fertilizers for improved soil fertility. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1365–1373, 2017

Modeling of breakthrough curves of N2, CH4, CO, CO2 and a SMR type off-gas mixture on a fixed bed of BPL activated carbon

In this work multicomponent breakthrough curve experiments of a SMR type off-gas containing hydrogen, carbon monoxide, methane and carbon dioxide on a BPL activated carbon fixed bed have been performed at 3 bar and temperatures ranging between 298 K and 338 K. The experimental results have been compared to predicted breakthrough curves simulated with a mathematical model with high accuracy. Pure component breakthrough curve experiments have been previously performed in order to obtain the adsorption capacities. The Langmuir isotherm model has been used for pure component adsorption and the Extended Langmuir isotherm model for multicomponent adsorption.

Adsorption Isotherm, Kinetic, Thermodynamic and Breakthrough Curve Models of H2S Removal Using CeO2/NaOH/PSAC

Dynamic adsorption is not suitable to be used to find the adsorption isotherm for H2S removal. It was because the conventional experimental method used grain adsorption for the isotherm calculation. In order to achieve grain adsorption using the fixed bed adsorption test rig, the amount of adsorbent was minimized to create a similar operation compare to grain adsorption, allowing the proper calculation of isotherm parameters. Data analysis showed that Freundlich sorption isotherm can best described the sorption behavior. Thermodynamic study showed that enthalpy change (∆H) and entropy change (∆S) were calculated to be -6.0 kJ/mol and 25.7 J/ mol.K. The sorption was pseudo-second order with activation energy 11.7 kJ/mol and rate constant was between 2.387–4.066 X 10 -6 g/mg.min for 30-70˚C. Breakthrough curve was fitted best by using breakthrough model developed by [1].

Modeling of breakthrough curves for aqueous iron (III) adsorption on chitosan-sodium tripolyphosphate.

A fixed bed column packed with chitosan-sodium tripolyphosphate (CTPP) beads was used to remove aqueous Fe (III) ions. The adsorption of Fe (III) ions on CTPP beads was found to be dependent on operating conditions, such as the flow rate, adsorbent bed length, and feed concentration. The experimental data were assessed with Thomas, Adams-Bohart and Yoon-Nelson models to predict the breakthrough curves using linear regression. The breakthrough curves were better fitted with the Thomas and Yoon-Nelson models when the flow rate was varied and the feed concentration and the bed height of the column were fixed. Therefore, chemical adsorption may be the limiting step that controls the continuous adsorption process. The Adams-Bohart model presented a good fit to the experimental data, showing that external mass transfer was controlling the adsorption process in the initial part of the breakthrough curves. The parameters obtained from the continuous adsorption assays may be used as a basis for designing columns packed with CTPP beads for the removal of Fe (III) ions.

Adsorptive removal of phenol from aqueous solution on a modified palm shell-based carbon: fixed-bed adsorption studies

In this study, activated carbon from oil palm shell was produced by two-step chemical activation using K2CO3 as the chemical activant in the ratio 1:2 for the removal of phenol in a fixed-bed column. The characterization of the carbon was carried by Fourier Transform Infrared spectroscopy, Scanning electron microscope, thermogravimetric analysis, zeta potential, Brunauer–Emmett–Teller (BET) surface area, Elemental and Proximate analysis. The Langmuir surface area, BET surface area, and pore volume of the carbon were 817 m2/g, 707 m2/g, and 0.31 cm3/g, respectively. The examination of several factors including bed depth, initial phenol concentration, and flow rate were carried out at constant pH of 6.5. The maximum sorption capacity of the carbon for phenol was 238.12 at 250 mg/L initial phenol concentration, 1 cm bed depth, and 9 mL/min flow rate. Thermodynamic parameters were determined to analyze the behavior of phenol uptake at different temperatures. Breakthrough curve models indicated that Yoon–Nelson model fitted the experimental data better than Adams–Bohart and Thomas models. According to the results obtained, activated carbon prepared from oil palm shell, modified with ammonia solution was an effective, sustainable, low cost, and alternative adsorbent for the removal of phenol in aqueous solutions.

Numerical Simulation of CO2 Adsorption on K-Based Sorbent

In this work, the equilibrium adsorption and the kinetic adsorptive breakthrough curve model have been established for CO2 adsorption on K-based sorbent. The equilibrium adsorption of CO2 on the studied K-based sorbent has been developed by several adsorptive equilibrium models to meet the perfect description of the adsorption performance of the K-based sorbent. Then, the kinetic breakthrough curve model is established on the basis of the equilibrium adsorptive model over a fixed bed, whereas the mass balance, the adsorptive equilibrium, and the kinetics of mass transfer with linear driving force (LDF) model have been taken into account to derive the partial differential equations of CO2 adsorption on the K-based sorbent. Moreover, the factors of both molecular diffusion (DA) and Knudsen diffusion (DK) have been considered with the internal mass transfer coefficient to describe the internal structure of K-based sorbent. The model results reveal that the kinetic model developed in this work strongly agrees...

Modeling and simulation of breakthrough curves of recombinant 503 antigen using immobilized metal affinity expanded bed adsorption chromatography

Abstract In this study a mathematical model was used to simulate the breakthrough curves of the recombinant 503 antigen of Leishmania infantum chagasi using immobilized metal affinity expanded bed adsorption chromatography. Initially, experimental curves were carried out in different conditions such as superficial liquid velocity, settled bed height as well as the initial 503 antigen concentration. The particle swarm optimization (PSO) algorithm was used for global parameter estimation by a general rate model, which proved to be an efficient tool for parameter estimation in chromatographic processes. Modeling and simulation of the 503 antigen breakthrough curves displayed a good performance during the estimation and validation stages. The highest global process efficiencies obtained was 88.8%. Finally, the validated model was used in the optimization stage, showing the process and column efficiencies of 89.2% and 75.9%, respectively. The results showed the applicability of this approach for modeling and optimization of chromatographic processes.

Capture of dioxin derivatives on activated carbons: breakthrough curve modelling and isotherm parameters

Four dioxin derivatives (benzene, chlorobenzene, dichlorobenzene and o-chlorophenol) were individually adsorbed onto each of four types of activated carbon (AC) derived from different raw materials. The observed adsorption bed capacities were in the range of 0.916-0.99, with the AC derived from coconut shell (ACC) having the highest bed capacity of 0.99. The micropore size significantly affected the adsorption. The adsorption behaviour evaluation of ACC by thermal gravimetric analysis revealed that the highest activation energy for desorption belonged to o-chlorophenol (107 kJ/mol), followed by dichlorobenzene (102 kJ/mol), chlorobenzene (55 kJ/mol) and benzene (42 kJ/mol). Thus, chemisorption predominated over the interaction between ACC and dioxin derivatives. The ACC was then selected as the absorbent to model the breakthrough curves of the adsorption of the dioxin derivatives using the Aspen gas adsorption simulation program. Langmuir isotherm parameters were determined, and the simulation was found to provide a high adsorption performance compared to the experimental results in all cases.

Capture of dioxin derivatives on activated carbons: breakthrough curve modelling and isotherm parameters

Four dioxin derivatives (benzene, chlorobenzene, dichlorobenzene and o-chlorophenol) were individually adsorbed onto each of four types of activated carbon (AC) derived from different raw materials. The observed adsorption bed capacities were in the range of 0.916-0.99, with the AC derived from coconut shell (ACC) having the highest bed capacity of 0.99. The micropore size significantly affected the adsorption. The adsorption behaviour evaluation of ACC by thermal gravimetric analysis revealed that the highest activation energy for desorption belonged to o-chlorophenol (107 kJ/mol), followed by dichlorobenzene (102 kJ/mol), chlorobenzene (55 kJ/mol) and benzene (42 kJ/mol). Thus, chemisorption predominated over the interaction between ACC and dioxin derivatives. The ACC was then selected as the absorbent to model the breakthrough curves of the adsorption of the dioxin derivatives using the Aspen gas adsorption simulation program. Langmuir isotherm parameters were determined, and the simulation was found to provide a high adsorption performance compared to the experimental results in all cases.

Breakthrough curve modeling of liquid-phase adsorption of fluoride ions on aluminum-doped bone char using micro-columns: Effectiveness of data fitting approaches

A comparative numerical analysis of three approaches for the breakthrough curve modeling has been performed using the experimental data of packed-bed fluoride adsorption on a novel aluminum-doped bone char using micro-columns. The performance of traditional Thomas and Yan breakthrough equations, a mass transfer model for a mobile fluid flowing through a porous media, and an artificial neural network with the optimal brain surgeon approach have been studied and discussed in the data fitting of asymmetric fluoride breakthrough curves. Results of this study highlighted the relative merits of tested breakthrough curve models for the non-linear adsorption data analysis involved in water defluoridation using a new adsorbent. In particular, the application of artificial neural networks is reliable for fitting highly non-linear adsorption patterns of priority water pollutants.

Adsorption of phosphate from aqueous solutions and sewage using zirconium loaded okara (ZLO): Fixed-bed column study

This study explores the potential of removing phosphorus from aqueous solutions and sewage by Zr(IV)-loaded okara (ZLO) in the fixed-bed column. Soybean residue (okara) was impregnated with 0.25M Zr(IV) solution to prepare active binding sites for phosphate. The effect of several factors, including flow rate, bed height, initial phosphorus concentration, pH and adsorbent particle size on the performance of ZLO was examined. The maximum dynamic adsorption capacity of ZLO for phosphorus was estimated to be 16.43mg/g. Breakthrough curve modeling indicated that Adams–Bohart model and Thomas model fitted the experimental data better than Yoon–Nelson model. After treatment with ZLO packed bed column, the effluent could meet the discharge standard for phosphorus in Australia. Successful desorption and regeneration were achieved with 0.2 NaOH and 0.1 HCl, respectively. The results prove that ZLO can be used as a promising phosphorus adsorbent in the dynamic adsorption system.

Dye removal from aqueous solution using coal fly ash for continuous flow adsorption

Coal fly ash was characterized at first in batch adsorption with acid and basic dyes. Good results of removal were obtained, although strongly dependent on initial dye concentration, ash dosage, and above all on pH of the solution. The maximum adsorption capacities per g of fly ash were 410 mg of Acid Blue 25 and 142 mg of Basic Blue 9, both with an ash dosage of 2 g/L at pH 11 after a contact time of 1 h. However, increasing the ash dosage to 20 g/L and contact time to 24 h, the maximum adsorption capacity of Basic Blue 9 raised 187 mg/g fly ash at pH 11, but this value was lowered to 8.4 mg/g at pH 7. Afterwards, flow experiments were carried out in semi-batch mode with a fixed amount of ash and continuous flow of dye solution in continuous stirred tank reactor, to determine the exhaustion curves of fly ash. The best fit of the results was obtained by a sigmoidal function referable to the breakthrough curve model of Yoon-Nelson. Successively, to reduce the alkali leaching by solution flow, in a semi-pilot scale plant, a continuous stream of dye solution was mixed in stirred tank reactor with a continuous ash slurry supply, and the resulting slurry was decanted in a settling tank to obtain a clarified supernatant stream outlet. In this last equipment, the optimum conditions were investigated to obtain the highest yields of dye removal from solutions at low concentrations (5–20 mg/L) such as those occur in rinsing waters arising from dyeing processes.

Multivariate Modeling and Prediction of Breakthrough Curves for Herbal Medicine Adsorption on Column Chromatography: A Case Study

This paper proposed an approach to predict the breakthrough curves for herbal medicine adsorption. The saponins adsorption process was taken as an example. The Yoon-Nelson model was used to fit the breakthrough curves of saponins and the model parameters in different batches were obtained. The model parameters were correlated with saponin concentrations in loading solution and flow rate using polynomial regression models. According to the polynomial regression models, the breakthrough curves could be predicted and the optimal adsorption end-point could be calculated early-on. This research provided a new method for predicting the end-points of the adsorption process of herbal extracts.

Substrate size and heterogeneity control anomalous transport in small streams

AbstractIn alluvial systems, substrate characteristics play a critical role in slowing downstream transport of both water and solutes. We present results from solute injection experiments testing the influence of sediment size (pea gravel versus coarse gravel) and heterogeneity (alternating sections versus well‐mixed reaches) on solute transport dynamics in four experimental streams at the Notre Dame Linked Experimental Ecosystem Facility. The stream with pea gravel resulted in more long‐term retention than the stream with coarse gravel, whereas both streams with heterogeneous substrate (alternated and mixed) fell between with similar late‐time scaling. Inverse modeling of solute breakthrough curves suggested that residence times were distributed according to a truncated power law. While conservative solute transport in all four streams was anomalous, truncation times were influenced by sediment size, with the smaller pea gravel exhibiting a later truncation time than the coarse gravel, and the two streams with heterogeneous substrate having an intermediate cutoff. These results uniquely associate transport scaling with substrate characteristics in fluvial systems, revealing truncation time scales that had been previously predicted but not observed and quantified in field conditions. Because both benthic (i.e., substrate‐water interface) and subsurface hyporheic regions are known biogeochemical hot spots, relating physical characteristics to the macroscopic transport behavior could be crucial to improve our estimates of solute export from fluvial systems.

Breakthrough Curve Analysis for Fixed-Bed Adsorption of Azo Dyes Using Novel Pine Cone—Derived Active Carbon

A novel activated carbon has been produced from pine cone, a sustainable resource, by phosphoric activation at 900 °C. The BET surface area of the activated carbon was 869 m2/g and the methylene blue isotherm area was 734 m2/g. The adsorption of two single-component acid azo dyes, Acid Blue 113 (AB113) and Acid Black 1 (AB1), onto this activated carbon was studied using fixed-bed adsorption. Breakthrough curves and equilibrium isotherms were obtained for the adsorption of these two dyes onto the prepared active carbon. The highest adsorption capacities achieved for AB113 and AB1 were 485 and 286 mg dye/g carbon, respectively. Two-column breakthrough curve models were applied to correlate the experimental adsorption breakthrough curves for each dye: the Thomas model, based on solid-phase internal diffusion, has been applied with considerable success; and the saturation isotherm model approach of Michaels was used with a reasonable degree of success.

Characterisation of hyporheic exchange in a losing stream using radon-222

summary Hyporheic and parafluvial flows between streams and the underlying streambed, or adjacent alluvium, are important drivers of biogeochemical cycling in streams. Here we present a new method for characterising this exchange in a losing stream based on longitudinal stream radon activities. A mass balance approach is used to constrain the radon influx into the stream and estimate exchange parameters: flux, residence time and exchange zone thickness. A net radon flux into the stream of 5.4 � 10 4 Bq m � 1 d � 1 is required to balance radon losses to groundwater recharge, gas transfer and radioactive decay. Given the radon production rate of the sediments (1.3 ± 0.7 Bq L � 1 d � 1 ), the minimum volume of alluvium flushed by either hyporheic or parafluvial exchange is 168 m 3 per m length of stream. Based on the stream width, depth of alluvial sediments and porosity, this implies that the exchange zone extends beneath the stream and an additional 11 m either side. The results of this new method are compared to two existing methods; streambed radon disequilibrium and transient storage modelling of breakthrough curves of an injected tracer. The stream radon mass balance provides a relatively simple means of estimating hyporheic (and parafluvial) exchange over tens to hundreds of kilometres of stream. Concurrent application of the stream radon method, transient storage modelling of injected tracer breakthrough curves and hydraulic methods is recommended to capture the full spectrum of hyporheic exchange in losing streams.

Modeling and simulation of breakthrough curves during purification of two chitosanases from Metarhizium anisopliae using ion-exchange with expanded bed adsorption chromatography

A mathematical model was developed to predict breakthrough curves during purification of the two chitosanases from Metarhizium anisopliae by expanded bed adsorption, taking into account the axial dispersion of liquid and using Streamline DEAE and SP XL adsorbents, anion and cation exchange resins, respectively. All the experiments were performed without clarification (with cells) aiming at the reduction of unit operations in future projects of separation processes, thereby reducing capital and operating costs. Chitosanases are enzymes that hydrolyze the carbohydrate chitosan, resulting in oligosaccharides that have many remarkable biological activities, such as anti-cancer, anti-HIV and antioxidant activities. The two adsorbents had similar performance in relation to hydrodynamics and mass transfer. The results of the parametric sensitivity analysis agree with the literature, and the model was validated with an average high degree of fit (94.68%) between simulated and experimental data obtained in this work.

Adsorptive removal of fluoride from aqueous medium using a fixed bed column packed with Zr(IV) loaded dried orange juice residue

The potential of the adsorbent prepared from DOJR marketed as cattle food in Japan was identified as an efficient and low cost adsorbent for fluoride using fixed bed column. DOJR was loaded with Zr(IV) ions to develop active adsorption sites for fluoride. Fluoride adsorption performance of column packed with Zr(IV) loaded DOJR was assessed under variable operating conditions such as Zr(IV) loading temperature, initial fluoride concentration, bed depth, initial pH, and flow rate. Breakthrough curve modeling showed that Thomas and bed depth service time (BDST) models were in good agreement with the experimental data. Application of adsorbent investigated in this study to the treatment of actual waste plating solution containing fluoride ion showed successful removal below acceptable standard in Japan using a fixed bed column, hence, Zr(IV)-DOJR can be expected to be a promising candidate for the treatment waste water containing trace amount of fluoride ion in fixed bed column.

Modeling of breakthrough curves of single and quaternary mixtures of ethanol, glucose, glycerol and acetic acid adsorption onto a microporous hyper-cross-linked resin

The adsorption of quaternary mixtures of ethanol/glycerol/glucose/acetic acid onto a microporous hyper-cross-linked resin HD-01 was studied in fixed beds. A mass transport model based on film solid linear driving force and the competitive Langmuir isotherm equation for the equilibrium relationship was used to develop theoretical fixed bed breakthrough curves. It was observed that the outlet concentration of glucose and glycerol exceeded the inlet concentration (c/c0>1), which is an evidence of competitive adsorption. This phenomenon can be explained by the displacement of glucose and glycerol by ethanol molecules, owing to more intensive interactions with the resin surface. The model proposed was validated using experimental data and can be capable of foresee reasonably the breakthrough curve of specific component under different operating conditions. The results show that HD-01 is a promising adsorbent for recovery of ethanol from the fermentation broth due to its large capacity, high selectivity, and rapid adsorption rate.