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Mass transfer performance of CO2 absorption is based on selecting an effective amine solvent, hence, an examination of the overall mass transfer coefficient (KGav) and CO2 removal efficiency, is significant for obtaining the most favorable CO2 capture performance. This study compared KGavand CO2 removal efficiency of the highly concentrated ternary amines solvent at various concentrations with the benchmark monoethanolamine (MEA) in a laboratory scale CO2 absorption packed-column. The six blends of 2-amino-2-methyl-1-propanol (AMP), piperazine (PZ), and MEA are formulated as ternary solvents at high PZ/AMP molar ratio (1.25–3.75) and total amine concentration (6M and 7M). Be noted that the solvent precipitation was not observed in this study. The absorption experiment was operated at 303 K temperature, 12% CO2 by volume, and CO2 loading of 0.25 mol CO2/mol amine. The experimental results showed that KGavand CO2 removal efficiency for AMP-PZ-MEA and MEA solvents increased as total amine concentration increased. Also, KGavand CO2 removal efficiency of the PZ-AMP-MEA solvent are greater than those of 5M MEA. An increase of PZ/AMP molar ratio had a positive influence on the absorption performance for ternary amines. In comparison with the benchmark 5M MEA, all the studied AMP-PZ-MEA solvents showed an outperformance. The two suggested formulae, which are 0.95:3.55:1.5 (6M) and 0.95:3.55:2.5 (7M), possessed approximately 1.5 and 2.5 times higher KGavand 17.34% and 17.63% greater CO2 removal efficiency compared with the benchmark 5M MEA.

In order to improve the mass transfer performance of packed column and investigate comparatively different absorbents, a monoethanolamine (MEA)-based lab pilot plant with CO2 absorption and desorption packed columns with CY-700 structured packings was built. The volumetric mass transfer coefficient (KGav) and CO2 capture rate of monoethanolamine (MEA) aqueous solution absorbing CO2 under different operating conditiions were investigated, and the regeneration energy consumption was also evaluated. The results show that KGav increases with the increasing liquid flow rate and decreases with the increase of lean CO2 loading and CO2 partial pressure. However, the increasing gas flow rate has negative effect on KGav. Liquid-to-gas ratios and reflux rate of condensate back to the desorber have significant effect on the working cyclic capacity and regeneration energy. Specifically, under the conditions with CO2 capture rate ≥90%, 5 L/h liquid flow rate and 0.48 m3/h gas flow rate, the regeneration energy and the cyclic capacity were about 85 MJ/kg CO2 and 0.67 mol/kg respectively. The findings verify the stability and repeatability of the CO2 capture pilot plant, and the good mass transfer performance of CY-700 packing, which also provide important comparative reference data of the baseline solvent for comparison with novel water-lean amine-based absorbents in the next step of work.

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Graphene oxide sheets fixed over silica particles (SiGO) and their modification functionalized with C18 and endcapped (SiGO-C18ec) have been reported as sorbents for extraction and analytical columns in LC. In this study, a SiGO column was selected as the extraction column and a SiGO-C18ec as the analytical column to study the applicability and limitations of a column-switching system composed exclusively of columns packed with graphene-based sorbents. Pyriproxyfen and abamectin B1a were selected as the analytes, and orange-flavored carbonated soft drinks as the matrix. The proposed system could be successfully applied to the pyriproxyfen analysis in a concentration range between 0.5 to 25 µg/mL presenting a linearity of R2 = 0.9931 and an intra-day and inter-day accuracy of 82.2–111.4% (RSD < 13.3%) and 95.5–99.8% (RSD < 12.7%), respectively. Furthermore, the matrix composition affected the area observed for the pyriproxyfen: the higher the concentration of orange juice in the soft drink, the higher the pyriproxyfen the signal observed. Additionally, the SiGO extraction column presented a life use of 120 injections for this matrix. In contrast, the proposed system could not apply to the analysis of abamectin B1a, and the SiGO-C18ec analytical column presented significant tailing compared to a similar approach with a C18 analytical column. [ABSTRACT FROM AUTHOR]

The challenging task in our ecosystem is to reduce acidic gas emissions to some extent. Many gases are emitted from the industries like H2S, CO, CO2, SO2, NO, and NO2 as exhaust gases. Among these gases, CO2, NO2, and SO2 are acidic, which results in adverse effects on humans, animals, and plants. The increase in the emission of CO2 gases from both anthropogenic and industrial sources resulted in CO2 mitigation studies. CO2 absorption studies were carried out using iron oxide nanofluid with the novel structured packed absorption column. Iron oxide nanoparticles were synthesized and characterized using XRD, SEM, and TEM analysis. Ammonia is used as an absorbent along with iron oxide nanofluid of three different concentrations (0.0001 w/v%, 0.001 w/v%, and 0.0015 w/v%). It was found that the iron oxide nanofluid of 0.0015 w/v% showed an improved % CO2 removal efficiency. This enhanced % CO2 removal efficiency was due to the increased interfacial area of the ameliorated contact between the liquid and gas phases. In addition, the magnetic field was introduced along with the packed column, which increased CO2 removal efficiency by 1.5%.

The challenging task in our ecosystem is to reduce acidic gas emissions to some extent. Many gases are emitted from the industries like H2S, CO, CO2, SO2, NO, and NO2 as exhaust gases. Among these gases, CO2, NO2, and SO2 are acidic, which results in adverse effects on humans, animals, and plants. The increase in the emission of CO2 gases from both anthropogenic and industrial sources resulted in CO2 mitigation studies. CO2 absorption studies were carried out using iron oxide nanofluid with the novel structured packed absorption column. Iron oxide nanoparticles were synthesized and characterized using XRD, SEM, and TEM analysis. Ammonia is used as an absorbent along with iron oxide nanofluid of three different concentrations (0.0001 w/v%, 0.001 w/v%, and 0.0015 w/v%). It was found that the iron oxide nanofluid of 0.0015 w/v% showed an improved % CO2 removal efficiency. This enhanced % CO2 removal efficiency was due to the increased interfacial area of the ameliorated contact between the liquid and gas phases. In addition, the magnetic field was introduced along with the packed column, which increased CO2 removal efficiency by 1.5%. [ABSTRACT FROM AUTHOR]

An Egyptian gas-producing plant located in the north of Egypt on the coast of the Mediterranean Sea near Port Said city is designed mainly to receive and treat natural gas produced from offshore wells. The plant designed capacity is around 2800 million standard cubic feet per day (MMSCFD), which gives it a highly appreciated strategic importance. The primary plant process is removing H2S associated with the produced gas using amine solutions. The plant contains seven units called gas trains, which use packed columns for the removal. An additional acid gas removal unit was involved in the early production facility, which uses trays column. This study presented a comprehensive comparison study for the columns, packed versus trays, at different operating conditions, including gas flow rate, gas temperature, lean amine concentration, lean amine flow rate, and lean amine temperature. Two models simulating these systems were built using ASPEN HYSYS V12.1 simulation software. The reliability of the two models was verified by comparing the results with plant actual data. The results showed similar behavior trends with changes in operating conditions to optimize the production capacity. For the early production facility unit, the gas to contactor temperatures has been optimized at 29.5 °C, lean amine temperature at 52 °C with 44.5% concentration. The lean amine temperature for the gas train unit has been optimized at 41.5 °C with a concentration of 36%. Both units were compared under the same operating conditions to determine the economically practical unit.

In chemical processes, packed columns are frequently employed in various unit operations. However, the flow rates of gas and liquid in these columns are often constrained by the risk of flooding. To ensure the safe and efficient operation of packed columns, it is crucial to detect flooding in real time. Conventional flooding monitoring methods rely heavily on manual visual inspections or indirect information from process variables, which limit the real-time accuracy of results. To address this challenge, we proposed a convolutional neural network (CNN)-based machine vision approach for non-destructive detection of flooding in packed columns. Real-time images of the packed column were captured using a digital camera and analyzed with a CNN model, which was been trained on a dataset of recorded images to identify flooding. The proposed approach was compared with deep belief networks and an integrated approach of principal component analysis and support vector machines. The feasibility and advantages of the proposed method were demonstrated through experiments on a real packed column. The results showed that the proposed method provides a real-time pre-alarm approach for detecting flooding, enabling process engineers to quickly respond to potential flooding events. [ABSTRACT FROM AUTHOR]

The octanol-air partition ratio (K OA) is a fundamental property used for screening chemicals for concern, depending on their potential to bioaccumulate and harm living systems. With millions of chemicals used in commerce, unfortunately, less than 800 compounds currently have experimentally measured K OA values due to limitations in traditional measurement techniques. We aimed to develop a direct gas chromatography retention time (GC-RT) method using a custom-packed column, with octanol as the stationary phase, for rapidly measuring K OA. We installed the column into a GC-mass spectrometry system and isothermally measured retention times of 15 volatile organic compounds. We calculated K OA values at experimental temperatures from the retention times and extrapolated the results to values at 25 °C using the Van't Hoff equation. Our directly measured log K OA values at 25 °C spanned 3.66 log units (0.820–4.48). Except for alcohols, our measured values agree with literature log K OA values (root mean square error, RMSE = 0.50). The discrepancy probably arose from differences in how well our method versus the literature methods capture measurement artifacts, specifically, gas-phase adsorption to the octanol phase and hydrogen bonding interactions. This proof-of-concept study demonstrates that our direct GC-RT method is promising for rapidly measuring K OA to support chemical risk assessment. [Display omitted] • Developed a direct GC- retention time method to measure octanol-air partition ratios. • Measured log K OA values ranged from 0.820 to 4.48 for 15 volatile compounds. • Measured log K OA values agree reasonably well with literature values. • This proof-of-concept demonstrates that our method is promising to support chemical screening. [ABSTRACT FROM AUTHOR]

Graphene oxide sheets fixed over silica particles (SiGO) and their modification functionalized with C18 and endcapped (SiGO-C18ec) have been reported as sorbents for extraction and analytical columns in LC. In this study, a SiGO column was selected as the extraction column and a SiGO-C18ec as the analytical column to study the applicability and limitations of a column-switching system composed exclusively of columns packed with graphene-based sorbents. Pyriproxyfen and abamectin B1a were selected as the analytes, and orange-flavored carbonated soft drinks as the matrix. The proposed system could be successfully applied to the pyriproxyfen analysis in a concentration range between 0.5 to 25 µg/mL presenting a linearity of R2 = 0.9931 and an intra-day and inter-day accuracy of 82.2–111.4% (RSD < 13.3%) and 95.5–99.8% (RSD < 12.7%), respectively. Furthermore, the matrix composition affected the area observed for the pyriproxyfen: the higher the concentration of orange juice in the soft drink, the higher the pyriproxyfen the signal observed. Additionally, the SiGO extraction column presented a life use of 120 injections for this matrix. In contrast, the proposed system could not apply to the analysis of abamectin B1a, and the SiGO-C18ec analytical column presented significant tailing compared to a similar approach with a C18 analytical column.

The paper presents the results of experimental studies on one- and two-phase flow in packed columns. In the study, natural materials (LECA, pumice stone, cones, coconut fiber, wood chips, walnuts, shells), waste materials (plastic nuts, bricks, tiles), copper springs, and plastic acorns were used as packing. The relationship between the flow resistance coefficient and the Reynolds number is described. In the model, the relationship between the pressure drop on the sprayed packing and the pressure drop on the dry packing is presented. The characteristic values for the studied materials were obtained. The study constitutes the basis for further studies of packings of various origins in order to determine the influence of variable geometrical dimensions. [ABSTRACT FROM AUTHOR]

• Absorption of CO 2 with NH 3 in packed beds is investigated. • A novel algorithm based on a dynamic model is proposed to design the packed bed. • The underlying model considers mass transfer and ion speciation in liquid phase. • The algorithms are experimentally validated under different operating conditions. • Low computational loads are needed to design the column according to this method. A novel model-based approach to design packed beds for CO 2 absorption with NH 3 is proposed and experimentally validated. The two-film theory is adopted to model gas/liquid mass transfer while the thermodynamic equilibrium among ion species is considered in the liquid. Such strategy allows to simulate both CO 2 absorption and NH 3 evaporation, that represent the most important aspects to improve capture efficiency and process cost-effectiveness. The resulting ODEs system is a two boundary-value problem which is solved by means of the shooting method. The model is then exploited to develop a new algorithm that, based on the adopted operating conditions, evaluates the packed bed height as a function of the desired capture efficiency. The height calculated for different combinations of operating conditions is successfully compared with the real height of the experimental column, thus confirming the reliability of the developed tool which can be run with very low computational loads. [ABSTRACT FROM AUTHOR]

Emisi karbondioksida ke atmosfer dianggap sebagai penyebab utama perubahan iklim, termasuk pemanasan global dan permasalahan pertanian. Berbagai teknologi pemisahan CO2 banyak dikembangkan. Absorpsi kimia adalah teknologi pemisahan yang paling efektif dan banyak digunakan dalam industri kimia maupun petrokimia. Dimana pelarut yang telah digunakan dapat di regenerasi kembali di kolom stripper. Stripping adalah proses regenerasi termal pelarut dimana larutan tersebut dikontakkan dengan pelarut gas yang tidak larut terhadap cairan tersebut. Penelitian ini bertujuan untuk mengembangkan simulasi unit stripping CO2 dalam packed column skala industri dengan mengestimasi kinerja unit stripping CO2 yang dinyatakan dengan % efisiensi kolom stripping dan komposisi gas yang keluar dari stripper. Simulasi dilakukan secara teoritis dengan mengembangkan model matematis untuk proses stripping CO2 dalam packed column skala industri. Selanjutnya hasil simulasi divalidasi dengan data riil pada salah satu industri pupuk di Indonesia. Variabel-variabel yang digunakan adalah tekanan operasi kolom, temperatur rich solution dan laju steam. Hasil simulasi untuk tekanan stripper 2,56 atm dengan laju rich solution 2943316 kg/jam dan temperatur rich solution 390 K menunjukkan CO2 (% mol) 99,038%, sedangkan data pabrik menunjukkan 97,5862%.

A continuous study was carried out in the up-flow packed bed column to remediate the Reactive Orange 16 (RO16) using biochar derived from coconut shell as a low-cost adsorbent. The sorption mechanism in the continuous process was carried out by studying the influencing parameters namely bed depth, solute flow rate and initial dye concentration. The continuous study explored a maximum uptake capacity of 46.63 mg/g at a bed depth of 25 cm, a flow rate of 0.3 L/h and an initial dye concentration of 100 mg/L. Mathematical modeling such as the Thomas model, modified dose– response model and Yoon–Nelson model was performed to fit the experimental data. Regeneration studies were carried out using 0.01 M NaOH and resulted in 99.7% desorption efficiency. The sorption–elution study concluded that the biochar can undergo three sorption–elution cycles. [ABSTRACT FROM AUTHOR]

Introduction: Hexavalent chromium is a highly toxic metal and it is considered one of the contaminants with the highest environmental impact. Bioadsorbents have been considered as a viable option for chromium removal, leading to the necessity to study the behavior of these adsorbents in unit operations similar to the ones employed in the industry. Objective: To study the potential of cassava peels as bio-sorbent in the adsorption of hexavalent chromium in a semi-continuous process in fixed bed columns. Methodology: The effect of parameters such as feed flow rate, initial concentration and bed column height on the response variables rupture time and removal capacity was analyzed using a laboratory scale experimental set-up. Results: Low feed flow rates, low initial concentrations, and higher bed height produce the best conditions for chromium removal. Additionally, three classical models for removal on the packed column were used to fit the dynamic behavior of this process and to obtain significantly physical parameters. However, the best fitting was obtained using the model of the response surface. Conclusions: The concentration of chromium in the feed stream is the experimental factor that has the most influence on removal capacity and rupture time in fixed bed columns packed with cassava peel.

Greenhouse gases emissions from large scale industries as well as gasoline based vehicles are mainly responsible for global warming since the 1980s. At present, it has triggered global efforts to reduce the level of GHG. The contribution of carbon dioxide (CO2) in polluting the environment is at a peak due to the excessive use of coal in power plants. So, serious attention is required to reduce the level of CO2 using advanced technologies. Carbon dioxide capture and storage may play an important role in this direction. In process industries, various carbon dioxide capture techniques can be used to reduce CO2 emissions. However, post-combustion carbon dioxide capture is on top priority. Nowadays the researcher is focusing their work on CO2 capture using hybrid solvent. This work highlights a review of carbon dioxide capture using various kind of hybrid solvent in a packed column. The various challenges for absorption efficiency enhancement and future direction are also discussed in the present work. It is concluded through the literature survey that hybrid solvent shows better efficiency in comparison to the aqueous solution used for CO2 capture. [ABSTRACT FROM AUTHOR]

• Pilot-scale experiments to investigate the performance of offshore columns. • The effects of liquid properties and operating conditions were analyzed. • An empirical reduction factor is proposed to capture the effects of permanent tilt. In this study, the effects of ship motion on the CO 2 absorption performance of the offshore columns (i.e., the separation columns installed on offshore floating units) are investigated. Specifically, a pilot scale column with 0.4 m diameter and 4 m packed height is used, and NaOH/air system is implemented to measure the CO 2 absorption performance of the column under both vertical and offshore conditions. The experimental results obtained from the vertical conditions are used to validate the mathematical model which can compute the effective surface area of the separation columns. Then, such model is used to produce the reference values for the experimental results obtained from the various offshore conditions, where tilt angle, roll motion conditions, liquid load, gas factor, liquid surface tension and liquid viscosity are used as the design variables. The reduction factor is proposed, which can describe the change in the absorption performance of the offshore columns with respect to the important factors. From our study, the tilt angle was shown to be the most important factor, and the mass transfer efficiency was reduced by 8.4% in average (compared to the value obtained under the vertical condition) when the tilt angle was 6°. It was also shown that the roll motion can enhance the absorption performance of offshore columns under certain operating conditions, and the maximum improvement (6.7%) in the mass transfer efficiency was achieved when the liquid load, roll motion amplitude and period were 14 m3/m2 hr, 8° and 45 s, respectively. [ABSTRACT FROM AUTHOR]

Carbon dioxide has many benefits such as in the production of dry ice, fire fighting, welding, and the production of carbonated drinks. As a result of these, it is important to develop a method to capture it effectively by reactive absorption using tertiary amine compounds, methyldiethanolamine (MDEA). Compared to primary and secondary amines, tertiary amines are inexpensive with a higher absorption capacity ratio of 1:1 (1 mole of CO2/1 mole of MDEA). One of its demerits is its slow absorption rate which can be improved by adding diethanolamine (DEA) and glycine as promoters. The purpose of this research is to determine the effect, type and concentration of promoter, its absorbent flow rate and solution temperature on CO2, as well as its removal percentage using a packed column filled with raschig ring. The concentration of CO2 gas absorbed was examined using an analyzer. The equipment used consists of columns with a diameter of 2”, column height of 80”, and filled with ¼” type raschig ring. Mixture of gases (10 % CO2, 90 % air) is flowed into the column using a predetermined flow rate. The 40 % MDEA absorbent varies with the glycine and DEA promoter concentration and the absorbent flow rate also varies from 0.20 to 0.60 L/min. The promoter concentration varies from 0 (no promoter) to 5 % while the MDEA inlet solution temperature varies from 40°C to 60°C. Based on the analysis, the best operating conditions for CO2 absorption using a DEA promoter of 3 % at 40°C with a flow rate of 0.20 L/min showed CO2 removal of 42.7 %. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Toluene partition coefficients in 23 ILs were in the range 0.5–3.5 Pa m3 mol−1. • Dichloromethane partition coefficients in 23 ILs were in the range 5–17 Pa m3 mol−1. • VOC diffusion coefficients in the range 1–4 × 10−11 m2 s−1 were measured in 4 ILs. • The computed toluene removal efficiency in a packed column was from 52 to 99.6%. • The computed dichloromethane removal efficiency in a packed column was lower than 44%. Abstract Partition coefficients of toluene and dichloromethane (DCM) in 23 hydrophobic ionic liquids (ILs), which can be used potentially for the physical absorption of volatile organic compounds (VOCs), were measured at 298 K. The partition coefficients, expressed as Henry's law constants, were 400–1300 times for toluene and 10–47 times for DCM lower in the selected ILs than in water. Thus, the toluene and DCM diffusion coefficients were measured in three high potential hydrophobic ILs and in [Bmim][NTf 2 ] using a thermogravimetric microbalance. Diffusivity measurements were performed at 298 K for toluene and between 278 and 308 K for DCM. Diffusion coefficients in ILs, ranging between 1 and 4 × 10−11 m2 s−1, were from 18 to 90 times lower than in water at 298 K. The diffusion coefficients were correlated to the temperature, the solute molar volume, the IL viscosity and molar volume with an average error of 4.2%. Finally, a 3 m industrial packed column was simulated for the removal of DCM and toluene in [AllylEt 2 S][NTf 2 ] and [bmim][NTf 2 ], which both present moderate viscosities of nearly 50 mPa s at 293 K. The overall mass-transfer coefficient, the removal efficiency and the pressure drop were calculated and compared to those obtained using other heavy solvents (a silicon oil and di-(2-ethylhexyl) adipate). This prospective simulation has demonstrated a good potential of ionic liquids for the toluene removal. Nonetheless, the DCM removal efficiencies simulated were lower than 44%. It suggests that even more efficient ionic liquids can be tuned and synthesized in the future for this specific application. [ABSTRACT FROM AUTHOR]

Contaminants of emerging concern (CECs) are mainly composed of products used in large quantities in everyday life such as pharmaceuticals, personal care products, surfactants, plasticizers, and different industrial additives. Some of the emerging contaminants are persistent and their complete removal is hard to achieve using conventional wastewater treatment processes. The current study focused on the application of classical Fenton process for the removal of selected pharmaceutical compounds (a sub-category of CECs). Acetaminophen was selected to represent this class of compounds and Fenton oxidation was carried out in a column packed with synthetic Zeolites analcime. Face-centered central composite design strategy was adopted to design and perform the experimentation. Three factors, pH, Fe2+:H2O2, and empty bed contact time, were used with three levels of each for experimental design. Quadratic model (with reduced terms) was observed to best fit the experimental data. Experimental results supported with ANOVA indicated that pH and Fe2+:H2O2 ratio had significant effect on removal of acetaminophen whereas empty bed contact time did not. pH (3–6) and Fe2+:H2O2 ratio (1.5–3) is available to achieve complete removal of acetaminophen. Acidic pH of 3, a limitation of homogeneous Fenton process, could be subdued by increasing the Fe2+:H2O2 ratio. The mechanism of removal of acetaminophen were observed to be Fenton oxidation as well as the adsorption on zeolites packed in column. [ABSTRACT FROM AUTHOR]

Carbon dioxide gas is a harmful impurity which is corrosive and it can damage the utilities and the piping system in industries. Chemical absorption is the most economical separation method which is widely applied in chemical industries for CO2 removal process. Hot potassium carbonate (K2CO3) is the most effective solvent that has been used extensively, especially for the CO2 separation process from gas synthesis and natural gas. This paper aims to develop mathematical model for investigating the CO2 absorption into promoted hot K2CO3 solution in industrial scale packed column in an ammonia plant. The CO2 was removed from the gas stream by counter-current absorption in two stages column. To represent the gas-liquid system, a rigorous mathematical model based on the two-film theory was considered. The model consists of differential mass and heat balance and considers the interactions between mass-transfer and chemical kinetics using enhancement factor concept. Gas solubility, mass and heat transfer coefficients, reaction kinetics and equilibrium were estimated using correlations from literatures. The model was validated using plant data and was used to compute temperature and concentration profiles in the absorber. The variation of CO2 recovery with respect to changes in some operating variables was evaluated. The effect of various kinds of promoters added into K2CO3 solution on the CO2 recovery was also investigated. The simulation results agree well with the plant data. The results of the simulation prediction, for the absorber pressure of 33 atm with a lean flow rate of 32,0867 kg/h, temperature of 343 K, and semi lean flow rate of 2,514,122 kg/h, temperature of 385 K, showed %CO2 removal of 95.55%, while that of plant data is 96.8%. © 2015 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

The calculation of column’s height plays an important role in packed columns precise design. This research is based on experimentally measurement of mass transfer coefficients in different heights of packed column to predict its height. The objective of presented work is to introduce a novel conceptual method to predict column height via new correlation for mass transfer coefficient. As the mass transfer coefficient is decreased with increase of column height, the HTU’s are not constant figures along the column so this new approach is called increasing HTU’s. The results of the proposed idea were compared with other correlations and the conventional method i.e. constant HTU’s. Since the results are in very good agreement with experimental data comparing to conventional method, it seems this approach can be a turning point in design of all differential columns like packed columns. Making use of this method is suggested for design of differential columns.

In order to investigate the gas separation ability of a column packed with nanozeolitic material, nano NaY zeolite was synthesized and granulated. These uniform granules packed in a chromatographic column were utilized for separation of Xe and Kr under various operating conditions. With regards to the response peaks obtained from trace injections of Xe and Kr into the column, the first and second normalized moments of peaks were calculated. Moreover, the height equivalent to a theoretical plate (HETP) for the column was determined. The results illustrated that the retention time of Xe was remarkably greater than Kr indicating that, the nano NaY zeolite was a good choice as an adsorbent in Kr and Xe separation process. Moreover, a simple and temperature dependent correlation was derived to predict the HETP for the packed column. Ultimately, the calculated HETP values were in a good agreement with experimental data.

In order to meet the requirements and well suit for in-situ process measurement of industrial scale gas-liquid mass transfer applications, such as natural gas processing and post-combustion carbon capture, electrical capacitance tomography (ECT) is used to analyse the distribution of a liquid phase across the packing of a counter current gas-liquid packed column and to quantify the liquid hold-up. The new method eliminates the requirement of a fully flooded reference calibration and only requires vacant and dry calibration steps. The calculation procedure is simplified by using a normal sensitivity matrix which does not include the packing information. The validity of the proposed method was confirmed through finite element method (FEM) analysis studies to certificate neither packing geometry nor orientation relative to the tomography probe nor had a significant impact on phase identification. An experiment is conducted on a counter current gas-liquid packed bed column with 190 mm diameter and polypropylene Sulzer Mellapak 250 Y as the packing. According to the experiment with various liquid load, the inclination angle of structured packing corrugation sheets has an impact on the radial distribution of liquid hold-up in the upper portions of packed beds and liquid hold-up fluctuations of ∼0.5% are observable below the flooding limit and even at no gas flow conditions which can meet the empirical correlations from literature. The experiment results show that the proposed method provides the confidence to use ECT in the industrial field service in gas-liquid packed column to provide the real-time liquid distribution and local liquid hold-up measurement. [ABSTRACT FROM AUTHOR]

A comparison between a traditional packed column and a novel membrane contactor used for CO2 absorption with carbonate production is addressed in this paper. Membrane technology is generally characterized by a lower energy consumption, it offers an independent control of gas and liquid streams, a known interfacial area and avoids solvent dragging. Those advantages make it a potential substitute of conventional absorption towers. The effect of the concentration and the flow rates of both the flue gas (10–15% of CO2) and the alkaline sorbent (NaOH, NaOH/Na2CO3) on the variation of the species present in the system, the mass transfer coefficient, and the CO2 removal efficiency was evaluated. Under the studied operation conditions, the membrane contactor showed very competitive results with the conventional absorption column, even though the highest mass transfer coefficient was found in the latter technology. In addition, the membrane contactor offers an intensification factor higher than five due to its compactness and modular character. [ABSTRACT FROM AUTHOR]

Due to the increasing world population and industrialization the worldwide energy requirement is also increasing. About 82% of the world’s total primary energy supply stems from fossil sources and coal combustion in power plants accounted for 46% of the 32.4 Gt global carbon dioxide (CO 2 ) emissions in 2014 (International Energy Agency, Key CO2 Emissions Trends: Excerpt from CO2 Emissions from Fuel Combustion (2016 edition)). The reduction of CO 2 emissions from power plant flue gases is therefore essential to enable reliable and ecologically benign energy supply. An efficient technology to reduce CO 2 emissions is reactive absorption in packed columns with aqueous amine-based absorption solvents, herein also called absorbents. The major drawback of conventional amine absorbents is their high absorption enthalpy, which causes high energy requirements during solvent regeneration. Alternative solvents that offer significantly lower absorption enthalpies suffer from lower absorption rates. To compensate for low absorption rates the enzyme carbonic anhydrase (CA) can be added to the absorbent to accelerate absorption kinetics by catalyzing the reaction between CO 2 and water. For industrial applications, it can be desirable to immobilize CA which extends enzyme longevity by confining the enzyme to favorable process conditions, prevents unnecessary exposure to high process temperatures, and enables enzyme reuse. The CO 2 absorption characteristics and handling properties of an innovative immobilized CA in the form of microparticles, called biocatalyst delivery system (BDS), were evaluated together with aqueous MDEA solvent. Operational feasibility parameters were validated in lab scale, followed by replicated CO 2 absorption performance tests in a small demonstration scale counter-current packed column. A sixfold enhancement in total absorbed mole flow of CO 2 in the presence of BDS was demonstrated versus blank MDEA solvent. Recyclability and longevity of BDS were validated. [ABSTRACT FROM AUTHOR]

Combined CO 2 and SO 2 absorption performance in a new combined capture process was evaluated in this work by experimental study using a lab-scale packed column system and a developed rate-based model in Aspen Plus. The combined absorption experiments were carried out to identify the impact of several key operating parameters, including flue gas SO 2 and CO 2 concentrations, CO 2 and SO 2 loadings, the absorption temperature, and the L/G ratio, on CO 2 absorption and NH 3 volatilization. Experimental results indicated that ≥85% CO 2 absorption efficiency was achieved in 5 wt% aqueous NH 3 solvent containing lean CO 2 loading at 0.2 mol CO 2 /mol NH 3 (C/N) and SO 2 loading at 0.1 mol SO 2 /mol NH 3 (S/N). The rate-based model was developed using the electrolyte-NRTL method and the RateFrac module in Aspen Plus, and validated as compared to the present experimental results. The modeling results showed that the SO 2 loading provided the similar effect on the CO 2 mass transfer, the absorption efficiency and the heat of CO 2 absorption as compared to the CO 2 loading, however, the SO 2 loading resulted in lower NH 3 volatilization compared to CO 2 loading. The lean CO 2 loading and the solvent flow rate dynamic adjustment approaches in association with the lean NH 3 solvent splitting process were studied to analyze the potential coordination of the combined absorption process and the sulfite treatment system. Maintaining 85% CO 2 capture efficiency was possible when SO 2 loading was increased from 0.1 to 0.2 S/N by reducing the lean CO 2 loading from 0.2 to 0.088 C/N or increasing the solvent flow rate from 8 to 14.1 L/h. The time window for the SO 2 treatment by the precipitation process was increased with the increasing split ratio of the lean NH 3 solvent splitting process that was associated with the dynamic adjustment approaches. In the present study, the discussion of the combined absorption experiments using the CO 2 and SO 2 loaded NH 3 solvent, the developed rate-based model, and the operation strategies provided valuable contributions to the advancement of the combined CO 2 and SO 2 capture process. [ABSTRACT FROM AUTHOR]

A permeable reactive barrier (PRB) using activated carbon and cast iron combined system was to be built at a field site in Northern China to remove Cr(VI) in the groundwater. In this study, laboratory column experiments were conducted to evaluate the efficiency of the combined system at mass ratios of 1:1 and 3:1. The results showed that the combined system has a higher removal rate than that of the single material and leads no secondary pollution. Different mass ratio was proved to have much effect on the Cr(VI) removal capacity (mg Cr/g materials), the removal capacity was 3.806 mg/g at 1:1, while it was only around 0.776 mg/g in the single cast iron column. Larger carbon particles and higher flow rate can lead to a significant decrease in Cr(VI) removal due to lower specific surface area and lower hydraulic residence time (HRT), respectively. The breakthrough curves could be adequately reproduced by the Dose-Response model, for security, the half-life time used in the PRB thickness calculation was 0.4d chosen at the break through time. The results could be useful to groundwater remediation at chromium-polluted sites. [ABSTRACT FROM AUTHOR]

The effect of the surface properties of collector beads on the transport of colloidal particles in porous media has been experimentally investigated. Both batch and continuous column experiments were conducted to study the dynamics of deposition and aggregation of colloids (polystyrene latex sulfate, d = 100 nm) in contact with collector particles (soda lime glass beads, d = 212–300 micron). Various rinsing methods were systematically used to wash the surface of soda lime glass beads. Time-resolved dynamic light scattering (TR-DLS) and ultraviolet-visible spectroscopy (UV–vis) were employed to evaluate the concentration of colloidal particles and their aggregation in columns packed with glass beads. Rinsing of glass beads was found to release the surface ions of collectors into the colloidal suspension and subsequently led to the aggregation of colloids. In batch experiments, leaching-induced increase of ion concentration in the suspension triggered the aggregation process, while, the collision frequency governed the aggregation dynamics later on. In column experiments, however, the initiation of aggregation by released ions was dependent on the length of the column. In a long column, a blocking-ripening mechanism was observed at the lower pH that indicated the concurrent aggregation and deposition of colloidal particles. In a short column, however, the concentration of eluted colloids did not decline over time that revealed incapability of leaching process to initiate aggregation. Furthermore, the solution chemistry was realized to be more effective in determining the fate of colloidal particles inside packed columns than the surface chemistry of collector beads. This study provides valuable insight into the effect of surface properties of collectors on aggregation and deposition of colloidal particles in a packed environment. [ABSTRACT FROM AUTHOR]

In the present study, an evaluation of the potential of the removal of hexavalent chromium on cassava peel (Manihot esculenta) in packed columns was made. In order to stablish the effect of parameters, such as feed flow rate, initial concentration, and bed column height, an experimental design was developed using the rupture time as response variable. Experimental results show that lower feed flow rates and initial concentrations and higher bed height produce the best conditions for the removal. Additionally, three classical models for removal on packed column were used to fit the dynamic behavior of this process and to obtain significantly physical parameters. However, the best fitting was obtained using the response surface model. [ABSTRACT FROM AUTHOR]

Summary: Textile dyes are hazardous and carcinogenic materials. Hence, their removal from wastewater is globally required. This research aims to remove anionic dye red bemacid E-TL from aqueous solutions using a biofilm supported on granular pozzolana in a fixed-bed column. The effect of different experimental conditions such as influent dye concentrations, flow rate and bed depth on red bemacid biosorption at room temperature were investigated. Results indicated that the breakthrough and saturation time increase with the decrease of the ow rate. The same effect is shown when the bed depth is increased. Favorable conditions for dye removal were observed with 60 cm of column height, lowest flow rate 1mL/min and initial red bemacid concentration of 60 mg/L; at which the highest removal efficiency of 52,68% were recorded. The breakthrough data obtained for RB E-TL removal fitted Thomas and Yoon-Nelson model with high correlation coefficients (R2 = 0,992). The results obtained proved that fixed microorganisms biomass could be a promising biosorbent for the removal of red bemacid from aqueous solutions in a dynamic process. [ABSTRACT FROM AUTHOR]

Biogas production and utilization is an emerging alternative energy technology that has gained importance since the price of oil and gas has increased steadily over the last two decades. Biogas primarily consists of methane (CH4) and carbon dioxide (CO2) with smaller amounts of hydrogen sulfide (H2S) and ammonia (NH3). For many applications the quality of biogas has to be improved. The main parameters that may require removal in upgrading systems are CO2 and H2S. This work presents the study of simultaneous absorption of CO2 and H2S by Monoethanolamine (MEA) solution in a packed column. Simulated biogas containing 40% CO2 and 60% N2 and biogas generated from an anaerobic digestion plant were used as feed gas streams. The effects of gas flow rate, L/G ratio and absorbent concentration were investigated. The performance of the system was found to vary with process parameters. Increasing L/G ratio and MEA concentration causes the system efficiency to increase whereas increasing gas flow rate results in lower efficiency. An operating condition of L/G ratio of 83.3 ml/L, gas flow rate of 3 L/min and MEA concentration of 3 mol/L was found to remove more than 99.5% of CO2 and H2S from biogas. The volumetric overall mass-transfer coefficient (KGav) for CO2 removal initially increases with increasing gas flow rate up to a certain value beyond which the coefficient becomes essentially constant. The KGav also increases with increasing L/G ratio throughout the range tested in this study.

A comparison between a traditional packed column and a novel membrane contactor used for CO2 absorption with carbonate production is addressed in this paper. Membrane technology is generally characterized by a lower energy consumption, it offers an independent control of gas and liquid streams, a known interfacial area and avoids solvent dragging. Those advantages make it a potential substitute of conventional absorption towers. The effect of the concentration and the flow rates of both the flue gas (10–15% of CO2) and the alkaline sorbent (NaOH, NaOH/Na2CO3) on the variation of the species present in the system, the mass transfer coefficient, and the CO2 removal efficiency was evaluated. Under the studied operation conditions, the membrane contactor showed very competitive results with the conventional absorption column, even though the highest mass transfer coefficient was found in the latter technology. In addition, the membrane contactor offers an intensification factor higher than five due to its compactness and modular character.

The presence of carbon dioxide (CO2) in the gas is not expected because CO2 can reduce heating value and CO2 is the major emission contributor into the atmosphere. Various separation technologies can be used to reduce CO2 content and improve quality of gas. Chemical or reactive absorption is most widely used because it provides higher removal rate. This paper will study the effect of the addition di ethanolamine (DEA) concentration into aqueous 30wt.% potassium carbonate(K2CO3) with reactive absorption method in a reactor packed column at temperature from 40°C to 80°C, DEA concentration range of (1% - 3%) and absorbent flow rate (0.5, 0.75 and 1) L. min1. Contacting the gas and absorbent are countercurrent flow in packed column with 1.5 m high and 50 mm in diameter. The absorption column was randomly packed with a packing material raschig rings 5 mm in diameter. The CO2 loading in the liquid samples was determined by titration. It is found that the best result of CO2 loading is 0.065594 mole/mole K2CO3 and CO2 removal 28%. The result show that the loading capacity (mole CO2/mole K2CO3) and CO2 removal increased with the increase of DEA concentration.

Methylene blue (MB) adsorption from aqueous phase was investigated. Pretreated walnut shell, as adsorbent was used. Experiments were conducted in a batch system for determination of sorption equilibria and then the data were incorporated in a packed column for the removal of MB from synthetic wastewater. The generated wastewater was contained 4 mg/l of MB. The wastewater was pumped through the column with flow rate of 18 ml/min and the effluent samples were collected. The effect of influent MB concentration (4 and 8 mg/l) and pH (5, 7 and 9) of wastewater on removal efficiency of dye were investigated. Langmuir adsorption isotherm model was implemented to interpret the experimental data. The obtained results revealed that the sorption data were well described by Langmuir model at pH value of 9. At contact time of 300 min, maximum equilibrium adsorption of MB uptake 6.7mg/g adsorbent was achieved.

This work concerns hydrogen sulfide (H2S) removal from biogas produced from wastewater of concentrated latexrubber industry (CLRI). H2S content in the biogas of CLRI is significantly high (i.e., up to 0.77 mol/m3 or 26,000 ppm) dueto the use of H2SO4 during rubber coagulation process. Attempts to treat biogas with high H2S have not been found in literaturereviews. In this work, a chemical oxidation using an iron-chelated solution catalyzed by Fe(III)EDTA is selected forthe treatment of such high H2S concentrations. Experiments were performed using an industry-size packed column withdiameter and packed height of 0.5 and 0.8 m, respectively. The biogas flow rate and H2S concentration were in the range of5.16x10-3 - 5.61x10-3 m3/s and 0.35-0.77 mol/m3, respectively. Experimental results indicated that Fe(III)EDTA solution waseffective at removing H2S from biogas with a maximum removal efficiency of 97%. Suitable operating conditions, includingFe(III)EDTA concentration, flow of Fe(III)EDTA and air flow rate were determined. In addition, no side-reaction of Fe(III) EDTA with methane was found. Thus, chemical oxidation using an iron-chelated solution catalyzed by Fe(III)EDTA is a promising technology for H2S removal from biogas produced from CLRI or other industries. Finally, a mathematical model of the absorption and the reaction between H2S and Fe(III)EDTA in a packed column is proposed and verified against the experimental data. The results confirm the potential use of the model to design packed column for H2S removal from biogas using absorption coupled with oxidation by Fe(III)EDTA.

Ammonia is a common chemical used in various industries. Emission of air contaminated with ammonia to the atmosphere without any treatment causes several effects on human health and environment.A high efficiency method for ammonia removal from waste air is then necessary. In this research, an absorption coupling with chemical reaction was investigated for ammonia removal from waste air using a packedcolumn. The packed column of 10 cm diameter and 200 cm height was packed with 1.4x1.4 cm Raschig rings. Three liquids including water, NaOCl and H2SO4 solution were used as an absorbent for the investigation.The objectives of this research were to determine a suitable absorbent and the optimum condition for ammonia removal from waste air. The packed column was operated at room temperature and atmosphericpressure. The tested conditions were as follows: the gas to liquid ratio (G:L ratio) was 35-90 m3 gas/m3 liquid, the inlet concentration of ammonia was 150-500 ppm and the air flow rate was 18 m3/h. The results showedthat the ammonia removal efficiency depends on type of the absorbent and the operating condition. The efficiencies increased with decreasing of G:L ratio and with increasing absorbent concentration. They were70%, 80-92%, and 95-100% for pure water, sodium hypochlorite solution and sulphuric acid solution, respectively. The efficiency decreased with time when water was used as an absorbent while it was almostconstant when NaOCl and H2SO4 solution were applied. The ammonia removal efficiency when using H2SO4 as the absorbent was not dependent on G:L ratio and inlet ammonia concentration, in the range used in thisinvestigation. Since H2SO4 solution gave the highest removal efficiency and can reduce ammonia concentration in waste air to levels which meet the TLV-TWA standard, it is recommended as an absorbent solution forammonia removal from waste air.

The oxygen concentration discharged from a compact adsorption-type oxygen concentrator decreases when water attaches to the zeolite particles used as a nitrogen adsorbent. In order to estimate the expansion of the water adsorption region in the zeolite column, it is necessary to measure the water diffusion occurring in a zeolite column after stopping PSA (Pressure Swing Adsorption) operations. Li-X type zeolite particles (molecular sieve OXYSIV-700) with particle diameters in the range of approximately 0.4–0.5 mm were used as a nitrogen adsorbent column of length 157 mm and of inner diameter 33 mm. By comparing the water concentration distributions obtained from MR (Magnetic Resonance) images and the distributions calculated by analytical solution of a one-dimensional diffusion equation under transient conditions, the counter diffusion coefficient of water absorbing on zeolite particles in the column was determined. The apparent diffusion coefficient of water absorbing on the zeolite particles moving into the zeolite column with macroscale pores was determined to be 1.25 ± 0.15 × 10 −11 m 2 /s. [ABSTRACT FROM AUTHOR]

The present investigation states the potential removal of emulsified oil from water using low cost modified adsorbents, bagasse and corn husk. The adsorbent surfaces were altered using sodium hydroxide and cetyl pyridium chloride (CPC) under normal rotary shaker, microwave and ultrasound medium, which were confirmed through SEM and BET analysis. The effects of modification on adsorption of emulsified oil were assessed by packed bed column studies in comparison with raw untreated bagasse and corn husk at a bed height of 100 mm, flow rate of 5 ml/min and a concentration of 3095 mg/l of emulsified oil molecules in water. The maximum dynamic adsorption for raw and modified adsorbents was evaluated through the break through curve and it was found to be 91%, for microwave assisted bagasse and corn husk. The efficiency of emulsified oil removal and adsorbent utilizes in the column have been calculated for raw and modified bagasse and corn husk. The experimental data fitted well with the Thomas and Yoon Nelson models. The regeneration of packed bed was achieved with 0.01 M HCl. The results explore that the modification of the adsorbents has highly supported and enhanced their adsorption efficiency in packed system. [ABSTRACT FROM AUTHOR]

Practical use of adsorption involves conducting the process in a packed bed column. The sorbent bed allows removing the contaminants from water or another solvent. Adsorption is most often applied to the treatment of aqueous solutions such as removal of hardness, heavy metal ions, colorants, pesticides, humus, and other organic and inorganic pollutants appearing in the water environment. Adsorption from low-concentration solutions is the main area of application of this process. Description of column adsorption presented in this paper uses a moving observer whose velocity is equal to the velocity of concentration front movement. This approach reduces the system of partial differential equations to ordinary differential equations. The method is able to predict the breakthrough time, saturation time as well as calculate the changes in concentrations with time and at different locations inside the column. Direct orange azo dye and properly prepared corncobs were used in the experiments. The column was operated at various initial dye concentrations, volumetric flow rates, and bed heights. [ABSTRACT FROM PUBLISHER]

Benzene hydrogenation via reactive distillation is a process that has been widely adopted in the process industry. However, studies in the open literature on control of this process are rare and seem to indicate that conventional decentralized PI control results in sluggish responses when the reactive distillation column is subjected to disturbances in the feed concentration. In order to overcome this performance limitation, this work investigates model predictive control (MPC) strategies of a reactive distillation column model, which has been implemented in gPROMS. Several MPCs based upon different sets of manipulated and controlled variables are investigated where the remaining variables remain under regular feedback control. Further, MPC controllers with output disturbance correction and, separately, with input disturbance correction have been investigated. The results show that the settling time of the column can be reduced and the closed loop dynamics significantly improved for the system under MPC control compared to a decentralized PI control structure. [ABSTRACT FROM AUTHOR]