Batch Column Research Articles

Undrained shear strength of soft clay reinforced with encapsulated stone dust columns

PurposeThe stone dust column was used to strengthen the sample and had a significant effect on improving the shear strength of the kaolin clay. The application of stone columns, which can improve the overall carrying capacity of soft clay as well as lessen the settlement of buildings built on it, is among the most widespread ground improvement techniques throughout the globe. The performance of foundation beds is enhanced by their stiffness values and higher strength, which could withstand more of the load applied. Stone dust is a wonderful source containing micronutrients for soil, particularly those derived from basalt, volcanic rock, granite and other related rocks. The aim of this paper is to evaluate the properties of soft clay reinforced with encapsulated stone dust columns to remediate problematic soil and obtain a more affordable and environmentally friendly way than using other materials.Design/methodology/approachIn this study, the treated kaolin sample's shear strength was measured using the unconfined compression test (UCT). 28 batches of soil samples total, 12 batches of single stone dust columns measuring 10 mm in diameter and 12 batches of single stone dust columns measuring 16 mm in diameter. Four batches of control samples are also included. At heights of 60 mm, 80 mm and 100 mm, respectively, various stone dust column diameters were assessed. The real soil sample has a diameter of 50 mm and a height of 100 mm.FindingsTest results show when kaolin is implanted with a single encased stone dust column that has an area replacement ratio of 10.24% and penetration ratios of 0.6, 0.8 and 1.0, the shear strength increase is 51.75%, 74.5% and 49.20%. The equivalent shear strength increases are 48.50%, 68.50% and 43.50% for soft soil treated with a 12.00% area replacement ratio and 0.6, 0.8 and 1.0 penetration ratios.Originality/valueThis study shows a comparison of how sample types affect shear strength. Also, this article provides argumentation behind the variation of soil strength obtained from different test types and gives recommendations for appropriate test methods for soft soil.

Facile room-temperature synthesis of a spherical mesoporous covalent organic framework for capillary electrochromatography

Herein, a spherical covalent organic framework COF TAPB-DMTP was facilely synthesized from 2,5-dimethoxyterephthalaldehyde (DMTP) and 1,3,5-tri-(4-aminophenyl)benzene (TAPB) as monomers. COF TAPB-DMTP with regular mesoporous and excellent mass transfer ability was first introduced into the capillary and immobilized on the inner wall of the capillary through a simple in situ growth method. Through various characterization results, COF TAPB-DMTP was successfully prepared and modified onto the capillary inner wall. The separation performance and potential of COF TAPB-DMTP modified capillary column was explored. The new developed COF modified column achieved a highly efficiency and selective separation between analytes with different properties, including halogeno benzenes, alkylbenzenes, phenols and sulfonamides. Satisfactory stability and reproducibility were observed on COF TAPB-DMTP modified columns. The intraday, interday and three batch columns relative standard deviations were all less than 1.85 % for the retention time. The separation performance of prepared column has no significant change after 90 continuous runs. Additionally, the COF TAPB-DMTP modified capillary column was successfully used for separation and detection of triazole antifungal drugs in human plasma, and the recoveries of three antifungal drugs (fluconazole, isavuconazole and posaconazole) in spiked samples were in the range of 98.6–100.8 %, 92.4–102.1 % and 99.9–107.5 %, respectively. This self-made column showed excellent application potential in chromatography separation science.

High Pressure-Driven Batch Distillation Optimal Control for Methylacetate-Methanol Separation

The pressure-swing distillation process with high-pressurized batch columns (HHP), with and or without a recycling stream, for separating methyl acetate-methanol is studied from the aspect of optimal control. The results show that even though not heat integrated, the HHP process benefits productivity. Based on the maximum recovery, the dynamic controllability without any kind of heat integration is researched. The optimal cyclic reflux ratio operating policy is extended to the separation of a third non-ideal minimum boiling azeotrope and close boiling mixture of industrial importance, and it shows significant reductions in energy expenditure since the derived discontinuous energy function tends to show cyclic "behavior" again. The proposed process, however, has the economic potential of both capital and energy by internal heat integration, ie. connecting the reboiler of the lower high-pressurized column to the condenser of the higher high-pressurized column. In the future, even more azeotropes, both minimum and/or maximum boilers, should be investigated in order to establish a "heuristic guidance" for HHP design and industrial usage.

Analysis of the Sludge Settling Behavior of the Kibendera Waste Stabilization Ponds in Ruiru, Kenya

Waste Stabilization Ponds (WSP) provide both cost-effective and high-performance wastewater treatment benefits in the tropical regions. The 3-month sludge settling behavior in the Kibendera WSP in Ruiru, Kenya, was studied between July and September 2022. The study aimed at determining the sludge volume index (SVI) and hindered settling velocity during the dry weather flow regime. Based on these experimental data, Vesilind Model was used to characterize the settling behavior in the anaerobic and primary facultative ponds. Whereas Standard Methods for the examination of water and wastewater were used to determine the total suspended solids (TSS) concentrations in the ponds, batch column settling tests were used to generate the batch settling curves for each pond. Generally, good settling behavior characterized by SVI values of less than 150 mL/g was observed during the study period. Highest settling velocities of 1.16 m/hr and 1.22 m/hr were recorded in the anaerobic and primary facultative ponds respectively for TSS concentrations of 0.6 g/L and 0.416 g/L. Optimal maximum velocity (<i>V_max</i>) values of 3.42 m/hr and 1.78 m/hr were observed in the anaerobic and primary facultative ponds respectively. The corresponding optimal model parameters (n) describing the measured data accurately were 0.47 L/g and 0.51 L/g respectively. The model parameters so obtained may be useful in characterizing the sedimentation behavior in the WSP during the dry weather flow regimes.

Aplikasi Pengolahan Limbah Batik Menggunakan Membran Keramik Berbiaya Rendah pada Kolom Batch

Batik is a characteristic of Indonesian culture which in the manufacturing process will produce waste as a residue from the colouring process. The waste still has a high colour content so if it is not processed further it will pollute the environment. This study aims to synthesize ceramic membranes from low-cost materials and apply the use of these membranes to treat batik waste in a batch column. The variable used in this study is the processing cycle, the results of the first processing are put back into the batch column for up to 3 iterations. The parameters tested were pH, turbidity and colour testing. The results showed that the ceramic membrane was able to treat batik wastewater with a maximum turbidity rejection % of 86.67 % and a maximum % rejection of 67.51 %. Low-cost ceramic membranes are effective for use as an alternative for batik waste treatment.

Production of phycobiliproteins, bioplastics and lipids by the cyanobacteria Synechocystis sp. treating secondary effluent in a biorefinery approach.

Cyanobacteria have been identified as promising organisms to reuse nutrients from waste effluents and produce valuable compounds such as lipids, polyhydroxyalkanoates (PHAs), and pigments. However, almost all studies on cyanobacterial biorefineries have been performed under lab scale and short cultivation periods. The present study evaluates the cultivation of the cyanobacterium Synechocystis sp. in a pilot scale 30 L semi-continuous photobioreactor fed with secondary effluent for a period of 120 days to produce phycobiliproteins, polyhydroxybutyrate (PHB) and lipids. To this end, the harvested biomass from the semi-continuous photobioreactor was transferred into 5 L vertical column batch photobioreactors to perform PHB and lipid accumulation under nutrient starvation. Three hydraulic retention times (HRT) (6, 8 and 10 days) were tested in the semi-continuous photobioreactor to evaluate its influence on biomass growth and microbial community. A maximum biomass concentration of 1.413 g L-1 and maximum productivity of 173 mg L-1 d-1 was reached under HRT of 8 days. Microscopy analysis revealed a shift from Synechocystis sp. to Leptolyngbya sp. and green algae when HRT of 6 days was used. Continuous, stable production of phycobiliproteins in the semi-continuous photobioreactor was obtained, reaching a maximum content of 7.4%dcw in the biomass. In the batch photobioreactors a PHB content of 4.8%dcw was reached under 7 days of nitrogen and phosphorus starvation, while a lipids content of 44.7%dcw was achieved under 30 days of nitrogen starvation. PHB and lipids production was strongly dependent on the amount of nutrients withdrawn from the grow phase. In the case of lipids, their production was stimulated when there was only phosphorus depletion. While Nitrogen and phosphorus limitation was needed to enhance the PHB production. In conclusion, this study demonstrates the feasibility of cultivating cyanobacteria in treated wastewater to produce bio-based valuable compounds within a circular bioeconomy approach.

Assessing the Wastewater Pollutants Retaining for a Soil Aquifer Treatment using Batch Column Experiments

In this study, the Secondary Treated Waste-Water (STWW) to infiltrate through the soil matrix, hence eliminating the contaminants in the effluent. For this study, three types of soil, such as loamy sand, fine sand, and clayey soil, were subjected to two cycles of wetting and drying to assess the type of soil that removes the maximum contaminants under which cycle. At diverse locations, soil samples were collected and examined to determine the soil types. Likewise, STWW was collected from Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) and Perungudi Sewage Treatment Plant (PSTP) to illustrate the quality of water before Soil Aquifer Treatment (SAT). About 1.5 m in height and 8 mm in diameter of fabricated acrylic material columns are used for the soil aquifer treatment efficiency studies. Water quality parameters, namely pH, TDS, and turbidity, were monitored throughout the study. All the organic compounds present in water were reduced to a higher level only in the fine sand in the one-day wetting/drying cycle. pH was reduced from 8.55 to 7.5, TDS was reduced from 1580 mg/l to 850 mg/l, and Turbidity was reduced from 7.24 to 4.04 NTU. This proposed method is to minimize the amount of water pollution from the environment. It is an effective way to manage aquifer recharge (MAR). SAT is the easiest method, aquifer and/or soil-based treatment systems improve the effluent quality of wastewater by removing the trace elements in the aquifer during the recharge of groundwater. It is likewise attractive for technologically advanced as well as emerging countries, and it is supple enough to allow adaptation to home-grown requirements by uniting it with predictable natural or bringing about water and technologies of wastewater treatment. Doi: 10.28991/CEJ-2022-08-07-011 Full Text: PDF

Densification of activated sludge for better settling performances: experimental characterization in batch column and model parameters calibration.

Conventional activated sludge (CAS) and densified sludge obtained using hydro-cyclone selective wasting were compared at a full-scale water resources recovery facility. The densified tested sludge, containing around 30-50% of aerobic granules, showed enhanced settleability with low and stable sludge volume index (SVI) compared to CAS, which suffered recurrent filamentous bulking. Further in-depth batch settling tests were carried out using a 40 cm diameter column fitted with ultrasonic transducers to monitor both sludge blanket height and vertical velocity profiles. Hindered settling and compression parameters were calibrated from the experiment for latter modelling use. Test sludge displayed more than doubled settling velocities compared to CAS, with hindered settling velocities remaining >3 m·h-1 even at high solids concentrations of 6.85 g·L-1. The compression regime was attained at much higher critical concentration for the test sludge. It also displayed enhanced thickening properties, with concentrations obtained after 30 min of settling being 20.9 and 8.5 g·L-1 respectively for test and control sludge. This allows for a substantial reduction of recirculation rates in practice. These results open perspectives in optimizing existing plant operation as well as clarifier design and modelling using densified sludge.

Experimental Data and Modeling the Adsorption-Desorption and Mobility Behavior of Ciprofloxacin in Sandy Silt Soil

The improved understanding of the behavior of antibiotics in soil is of great importance due to their environmental hazard and frequent detection. In this work, the adsorption-desorption and mobility behaviors of ciprofloxacin in sandy silt soil, affecting the fate of ciprofloxacin in the environment, were studied by a series of batch tests and column tests. In batch tests, the effects of contact time, initial ciprofloxacin concentration, sandy silt soil dosage, solution pH, and ionic strength on ciprofloxacin adsorption and desorption in sandy silt soil were considered. Adsorption results were satisfactorily modeled, with good fittings to the pseudo-second-order model (R2 &gt; 0.999) and Langmuir model (R2 &gt; 0.991), with the value for Langmuir’s maximum adsorption capacity (qm) 5.50 mg g−1. Ciprofloxacin adsorption decreased sharply by increasing the pH from 7.0 to 10.0 and the ionic strength from 0.01 to 0.2 mol L−1 CaCl2. Comparatively, ciprofloxacin was more readily desorbed from sandy silt soil at alkaline and high ionic strength conditions. Breakthrough curves of ciprofloxacin obtained from the column experiments were described by the two-site model, Thomas model, and Yan mode. Of these models, the two-site model was the most suitable to describe the mobility of ciprofloxacin. The retardation factor (R) obtained in the two-site model was 345, suggesting strong adsorption affinity with ciprofloxacin on the sandy silt soil surface. The results from the Thomas model suggested the extremely small external and internal diffusion resistances. The Yan model was not suitable. Cation exchange interaction, electrostatic interaction, mechanical resistance, entrapment between porous media, and gravity sedimentation were proposed to be the important adsorption mechanisms.

Silico antimonate nanocomposite material: I- preparation, characterization and its application for separation of strontium and rubidium from aqueous solutions

ABSTRACT Sorption of Sr(II) and/or Rb(I) onto synthesised silico antimonate (SiSb) nanocomposite was investigated in this work, using batch equilibrium and column techniques. SiSb was fabricated by precipitation technique and characterised by various analytical tools. The adsorption of Sr(II) and/or Rb(I) includes the influence of shaking time, distribution coefficient, kinetics, capacity, and column separation. The data prove that SiSb has a quick equilibrium time (40 min), the distribution coefficients (Kd) as a function of pH have maximum separation factors ( α R b S r ) equal to 162.1 at pH 6, reaction kinetics follow a pseudo-second-order model, sorption capacity for Sr(II) and Rb(I) is 48.5 and 13.8 mg/g, respectively. Column data reveal that Sr(II) can be loaded and separated from Sr(II)-Rb(I) as a simulation model for Sr(II) recovery from its Sr(II)-Rb(I) system using different concentrations of HNO3 as eluent.

Density-modification displacement using colloidal biliquid aphron for entrapped DNAPL contaminated aquifer remediation

Colloidal biliquid aphron (CBLA) is a strong density modifier for dense nonaqueous phase liquids (DNAPLs). However, the underlying mechanisms responsible for density modification and displacement is not yet clear. Here, a series of batch column and sandbox experiments were conducted to achieve substantial removal and irreversible density reduction of tetrachloroethylene (PCE). The mass of PCE retained in the column and sandbox was less than 1% under suitable injection conditions, and the density of PCE in the effluent was less than that of water (fluctuated in the range of 0.74–0.96 g/cm3). The displacement process was controlled by the high viscosity ratio of CBLA to PCE (52.3). The emulsified and dissolved phase of PCE formed after reaction with CBLA, and the light nonaqueous phase liquid (LNAPL) phase formed after injecting demulsifier solution. The phase analysis played a significant role in monitoring the changes in concentration and density of PCE. The density-modification displacement technique using CBLA reduced the mass of residual PCE by a factor of 165 compared to surfactant flushing, and there was no risk of downward migration of PCE. This study contributes to a better remediation of entrapped DNAPL in contaminated aquifer.

Development of Integrated Electrocoagulation-Sedimentation (IECS) in Continuous Mode for Turbidity and Color Removal

The present work focused on the development and evaluation of a compact electrocoagulation (EC) reactor, combined between EC and clarifier processes in continuous modes for decolorization and turbidity removal, named the integrated electrocoagulation-sedimentation reactor (IECS). The experiments were firstly conducted in the four-liter batch column in order to optimize the EC configuration and operation condition. The removal kinetics were also investigated and predicted for kinetic correlations. After various optimization steps, the IECS reactor was conducted, consisting of EC and clarifier compartments. Liquid flow pattern in EC compartment was examined through resident time distribution technique for defining the number of EC units and divided baffles. In summary, four units of EC were placed in the EC compartment of the IECS reactor with 90% in the width of three baffles. Each EC unit had two pairs of aluminum electrode plats in monopolar arrangement with a 1.5 cm gap and required a current density of 13.5 mA/cm2. For the clarifier compartment, it was mainly designed based on the batch settling test for separating the precipitated particles. The treatment performance of the IECS reactor was tested at different liquid flows in order to reduce the pollutant to a certain level. For the individual condition, liquid flow rates of 3 and 1 L/min were defined for turbidity and color, respectively. If both pollutants are presented simultaneously, a liquid flow rate of 1–2 L/min can be used for decreasing turbidity from 250 to &lt;20 NTU and color from 6000 to &lt;300 ADMI.

Modeling and Simulation of a Packed Column Batch Still for Fruit Wine Distillations

Batch distillations are extensively used worldwide to produce fruit wine spirits with distinctive aromas. These processes are typically operated manually, based on the experience of the distiller. However, dynamic optimization and automatic control strategies could be valuable for ensuring a more consistent product and quickly adapting to new market tendencies. Consequently, reliable process models are required for the application of these methods. The novelty of this study is developing a highly efficient method to reliably simulate and calibrate a rigorous first-principles model of a packed batch column still. We applied the method of lines (MOL) to transform the partial differential equations describing the packed column dynamics into an ordinary differential equation (ODE) system. The nonlinear phase equilibrium equations were pre-solved, and several polynomials were fitted to get explicit algebraic equations. The final differential-algebraic system (DAE) comprises 31 ODEs, 113 explicit algebraic equations, and two implicit algebraic equations. Variables scaling, smoothing of discontinuities, and applying an algebraic loop within Simulink to solve the implicit algebraic equations resulted in 600 times faster simulations than a na&#x00EF;ve approach. The model was regressed using pilot-scale experimental data and subjected to extensive validation using independent data. Sensitivity and residual analysis established that a better heat loss model could improve ethanol concentration prediction. This new heat losses model reduced the average ethanol concentration error by more than five times. The developed model can be applied to design reliable control systems and optimal operating strategies for packed column batch distillations.

Modelling of chromatographic carboxylic acid fractionation with a strong anion exchange resin in sulfate form

Chromatographic fractionation of complex mixtures of carboxylic acids with a strong anion exchange resin in sulfate form as separation material was modelled. The studied system contained lactones of two isosaccharinic acids, four dissociating monocarboxylic acids (lactic acid, glycolic acid, acetic acid, and formic acid), and two strong electrolytes (Na2SO4 and H2SO4). The sorption equilibria in the studied system are complex because of three distinct sorption mechanisms: affinity-based interactions, site sharing, and ion exchange. Modelling of the sorption equilibria was attempted using simple sorption isotherms models: the Sheindorf–Rebuhn–Sheintuch (SRS), the Langmuir, and the Sips models. For simplicity, the electrolytes were treated as molecular components (without dissociation). In the case of pure carboxylic acids, both the SRS (residuals 10–5–10–4) and Sips models (residuals ∼ 10–7–10–5) correlated well with the experimental data. However, the Langmuir model was found to be inadequate. In the case of competitive sorption, the SRS model (residuals 10–6–10–4) correlated well with the data, but the Sips model’s (residuals ∼ 10–2) predicted sorption was too strong. Additionally, the sorption of Na2SO4 was well predicted by the SRS model. For each component pair, only a single interaction parameter was required with the SRS model. The sorption equilibria (SRS) model and the column mass balance model were validated against data from batch column experiments done with carboxylic acid-rich feed solutions. Pure water or aqueous carboxylic acid and salt solutions were used as eluents. The model accurately predicted the elution profiles in each case. The characteristic shapes of the carboxylic acid elution profiles with the effects resulting from competitive sorption were well accounted for. Strong sensitivity of the studied system towards changes in pH and H2SO4 concentration was observed.

Competitive adsorption of Ni(II) and Cu(II) ions from aqueous solution by vermiculite-alginate composite: batch and fixed-bed column studies

The present study introduces vermiculite-Alginic composite (VMT-ALG) as a low-cost adsorbent for the uptake of Ni(II) and Cu(II). The fabricated composite was characterized by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) analysis. The different process parameters such as contact time, pH, initial heavy metal concentration, and temperature were optimized. According to the experimental data, the Freundlich adsorption model with the coefficient determination of 0.9945 and 0.9925 is the best isotherm model to describe the adsorption of Cu(II) and Ni(II) by VMT-ALG, respectively. Also, the equilibrium study confirmed the heterogeneous adsorption for Ni(II) and Cu(II). Kinetic studies indicate that intra-particle diffusion would be the significant rate-limiting step of the adsorption process. Thermodynamic studies indicated that the adsorption process was physisorption and endothermic. Research on fixed-bed column (20 cm length and 1.0 cm inner diameter) has been carried out under different volumetric flow rates (10 and 20 ml/min) and different initial concentrations of Cu(II) and Ni(II) (250, 500, and 750 mg/l). The results of column data were successfully explained using the Thomas and Yoon–Nelson models. Finally, continuous adsorption studies for Cu(II) and Ni(II) simultaneous uptake from aqueous solutions were conducted by VMT-ALG composite. The results indicated that the adsorption capacity of Cu(II) and Ni(II) both increased with an increase in the concentration of metal ions, and decreased with an increase in the flow rate.

Removal of Atrazine by Biogenic Manganese Oxide in Batch and Fixed-Bed Column Reactors

Atrazine is a widely used herbicide today and is usually detected at high concentrations in aqueous media. Its presence in aquatic environments poses a serious risk to human and environmental health. Adsorption is a promising technology for the removal of persistent organic materials. In this study; dried biogenic manganese oxide (BMO) as a novel adsorbent material was used to control the atrazine pollution. The removal of atrazine by dried BMO was investigated in batch and fixed-bed column reactors. Batch studies revealed that maximum atrazine removal was 98.1% at a temperature of 50 °C, pH: 12.0 and an atrazine concentration of 0.5 mg L−1. The maximum atrazine adsorption capacity was 2.124 mg g−1 at 50 °C, pH: 12.0 and atrazine concentration of 10 mg L−1. The Freundlich isotherm fitted very well to experimental data. Adsorption followed the pseudo-first-order type kinetic. Thermodynamic values such as Gibbs free energy, enthalpy and change in entropy were measured as −26.02 kJ mol−1 (30 °C), 106.48 kJ mol−1 and 0.43947 kJ mol−1 K−1, respectively and the adsorption process was found to be spontaneous and endothermic. The effects of parameters such as feed flow rate, initial atrazine concentration and BMO amount on the atrazine removal were investigated in a fixed-bed column reactor. When a flow rate of 4 mL min−1, atrazine concentration of 2 mg L−1 and BMO of 2 g were used, the equilibrium atrazine uptake (q eq) was 0.41 mg g−1.

Investigating the processing capacity of batch distillation by applying a second, smaller column

Increasing the processing capacity is important, especially in the pharmaceutical industry, where a given amount of waste solvent must be processed in a specific time period, else the remaining amount of waste solvent must be incinerated, which results in organic solvent loss and considerable environmental impact. In this paper, the possibility of increasing the processing capacity of batch distillation by using a second, already available, smaller batch column in addition to the original one is studied. The size of the columns is not changed during the calculations performed. Two case studies are presented. In the first one (Mixture 1), acetone, in the second one (Mixture 2), acetic acid must be recovered in high purity from their aqueous mixtures by operating either the larger column only or both columns simultaneously. The smaller column serves for preliminary separation, and its main-cut (Mixture 1) or residue (Mixture 2) is further processed in the larger one. The goal of this work is to maximise the processing capacity of the two-column process with the same recovery as in the single-column process. Both processes are modelled with a professional flow-sheet simulator. For the single-column process, the only independent variable is the reflux ratio. For the two-column process, the independent variables are the reflux ratios of both columns and the amount of intermediate product (distillate or residue) of the first column transferred to the second one. The ranges of the independent variables are determined by sensitivity studies for different charge compositions (20–50-80 mass% acetone or acetic acid), and each case is optimised by a genetic algorithm coupled to the flow-sheet simulator. It is also shown in this work that the processing capacity maximum of the two-column process is not always at the equality of the processing times of the two columns.

H-Clinoptilolite as an Efficient and Low-Cost Adsorbent for Batch and Continuous Gallium Removal from Aqueous Solutions

In this paper, the gallium (III) ions’ adsorption onto protonated clinoptilolite (H-CLP) was investigated both in batch and fixed-bed column experiments. Regarding batch experiments, the influence of some parameters such as adsorbent dosage, size particle, and temperature was studied, determining that a dosage of 10 g/L for an initial pollutant concentration of 40 mg/L leads to a removal percentage over 85% regardless of particle size and temperature. On the other hand, adsorption of gallium onto H-CPL is an endothermic and spontaneous process in the studied temperature range, concluding that the maximum adsorption capacity was 16 mg/g for 60 °C. Concerning to the effect of the presence of other cations in solution, such as Na+, K+, or Ca2+, gallium adsorption capacity only drops by 20%, although the initial concentration of other cations in the solution is 50 times higher than gallium concentration. This means that clinoptilolite has a high affinity for gallium which can be very favorable for further selectivity tests. A crucial factor for this high selectivity could be the protonation of clinoptilolite which allows working without modifying the pH of the aqueous solution with acid. In the fixed-bed experiments, breakthrough curves were obtained, and the effect of operation variables was determined. A breakpoint value of 254 min for 64 g of adsorbent and flow rate of 9.0 mL/min (7.0 BV/h) were obtained, when treating a pollutant volume of 33 BV. Additionally, the breakthrough curves were fitted to different models to study the particle size effect, being the best fit corresponding to the Adams–Bohart model. This fact confirmed the influence of particle size on adsorption kinetics.Graphical

Influence of still design and modelling of the behaviour of volatile terpenes in an artificial model gin

Behaviour of volatile compounds in gin distillation using a batch column laboratory still has been investigated altering distillation parameters such as reflux strategy, pressure, and still design (column configuration). The distillate was separated into four equal fractions and ten volatile terpenes were quantified. Experimental values were compared to calculated data using a dynamic model calculated with ProSim BatchColumn software using a non-random two-liquid model to describe the interaction between solvents and terpenes. In the simulation different terpenes were considered and clustered into three group profiles. The monoterpene group was found to be the most volatile resulting in the highest concentration in the first fraction and depleting towards the end. The oxygenated terpenes increased in concentration with depleting ethanol concentration in the still and were therefore the least volatile compounds whereas the two representatives of the sesquiterpenes were found to be semi volatile. Changes in the column configuration resulted in major differences in the total concentration of terpenes extracted. The change of reflux strategy resulted in a higher concentration of the more volatile fraction at the higher reflux ratio chosen. The model showed a moderate agreement with the experimental data and only the monoterpenes considered showed good agreement.

Experimental Design of the Multicolumn Countercurrent Solvent Gradient Purification (MCSGP) Unit for the Separation of PEGylated Proteins

The rapid growth and diffusion of biopharmaceuticals, including polyethylene glycol (PEG)–protein conjugates, required to set up stringent regulatory requirements, in terms of purity and clinical safety. In order to produce proteins that meet these requirements, the development of robust purification methods has been one of the main goals in the field of downstream processing in the last years. Most of these methods rely on single or sequential batch chromatographic separations, enabling one to reach the purity specification but often at the expense of low yield. An appealing alternative is the Multicolumn Countercurrent Solvent Gradient Purification (MCSGP). Thanks to the internal recycling of the fractions where product and impurities coelute, this process can provide a significant improvement in the process yield, preserving the purity specification. The drawback lies in the increased number of process parameters, compared to the batch, which complicates the design and optimization of this unit. In this work, we propose an ad hoc design procedure for the optimization of central-cut separations at a target purity. Using PEGylated lysozyme as a model system, we illustrate the use of this procedure to identify the load, the elution gradient as well as the collection intervals for optimal yield and productivity, at fixed purity specifications, for a batch (single) column system. The obtained optimal process parameters are subsequently transferred to the MCSGP unit. The so-designed MCSGP process exhibited superior performances compared to the corresponding optimal batch process by increasing the yield and productivity by 17.0% and 2.1%, respectively, at the purity specification of 80%.