Small Column Research Articles

COMPRESSIVE BEHAVIOR OF CONFINED RC COLUMNS BY FIBROUS JACKET

The current study conducted to examine the effect of strengthening of RC square short columns with fibrous jackets. Experimental and theoretical study included fabrication 16 column, seven columns were fabricated experimentally and ten parametric columns were modeled theoretically by ANSYS software. The parametric study included testing of two series of columns under axial compression load. The first series included eleven small scale columns retrofitted by fibrous jacket reinforced by were fabricated experimentally and theoretically with many variables such as jacket thickness, strengthening type (hoop and composite), vertical and inclined rebar, in addition to columns with larger length. The second series included testing of five full scale-columns modelled numerically and strengthened with composite and hoop fibrous jacket with different jacket thicknesses. The test results showed that the fibrous jacket enhanced the stress capacity, ductility, toughness, deformation capacity, and energy absorption. Increase the jacket thickness (25 to 45 mm) increased the ultimate load carrying capacity by (54%). Hoop jacket enhanced the ultimate stress capacity more than composite case by (19.7%). Concerning the theoretical side, 3D simulation by finite element analysis of ten columns with different parameters. Hoop fibrous jacketed column with inclined reinforcement enhanced the ultimate stress by (35%) while the column with reinforced jacket by both steel fibers and steel reinforcement showed less enhancement by 13%. Increase the length of the strengthened column decrease the average enhancement in the ultimate stress by (17%). Strengthening full scale columns with composite fibrous jacket with thicknesses (5, 6, and 7) cm showed an enhancement in the load carrying capacity by (177%, 210%, and 245%) respectively. Hoop jacket in the full-scale column was better than composite one which showed that the hoop jacket carried stress more than composite one by (67%) approximately.

A Preliminary study of removal of some heavy metals from aqueous medium by a mesoporous hydroxysodalite zeolite prepared from basalt rich in calc-plagioclaseby alkali activation

This work presents an exploration of the use of hydroxysodalite zeolite prepared from basalt rich in calc-plagioclaseby alkali activation for removal of some heavy metals from aqueous medium. The preliminary results of batch and column experiments indicated a quantitative and fast removal of the three investigated ions, Cu 2+ , Pb 2+ and Zn 2+ from aqueous solutions. The data from the batch experiments and the column experiments jointly support the notion that hydroxysodalite zeolite prepared from basalt rich in calc-plagioclase is an efficient adsorbent for the investigated heavy metals. Almost quantitative removal of the ions was achieved within a period of 15 min of exposure of the solution to the adsorbent in batch experiments and through passing a small column filled with the adsorbent. The highest removal efficiency by the zeolite prepared from basalt rich in calc-plagioclase of the three tested heavy metal Cu 2+ , Pb 2+ and Zn 2+ were 99.98% ,99.76% and 99.93 % respectively. Keywords: hydroxysodalite zeolite, basalt utilization, heavy ions removal, pollution remediation DOI: 10.7176/CMR/12-7-09 Publication date: November 30 th 2020

Enhanced Removal of Heavy Metals from Water by Hydrous Ferric Oxide-Modified Biochar.

Biochar has become an attractive adsorbent for heavy metal removal, but its application potential is very limited because of the relatively low adsorption capacity and poor selectivity. In the present study, we decorated the biochar (BC) by impregnating hydrous ferric oxide (HFO) within the pore of biochar and consequently obtained a new hybrid adsorbent denoted as HFO-BC. The results show HFO-BC exhibited excellent performance to two representative heavy metals, i.e., Cd(II) and Cu(II), with maximal experimental sorption capacities of 29.9 mg/g for Cd(II) and 34.1 mg/g for Cu(II). HFO-BC showed satisfactory anti-interference ability for Cd(II) and Cu(II) removal in the presence of high levels of Ca(II) and Mg(II) owing to the specific inner-sphere complexation between the immobilized HFO and Cd(II) and Cu(II), which was probed by XPS analysis. Cd(II) and Cu(II) removal onto HFO-BC experienced two distinct stages prior to be adsorbed, i.e., migration from solution to the outside surface of adsorbent and pore diffusion and approached equilibrium within 100 min. In the laboratory-scale small column adsorption experiment, HFO-BC can generate ∼129 and 300 BV effluents for Cd(II) and Cu(II), equivalent to 774- and 1854-fold of its own weight, to meet their treatment standards. Moreover, the exhausted HFO-BC can be effectively regenerated using HCl–CaCl2 binary solution with a desorption rate more than 95%. All results validate that impregnating HFO inside the pores of BC is a promising approach to promote the practical applicability of BC for removing heavy metals from the polluted water.

Measurement Device for Ambient Carbonyl Sulfide by Means of Catalytic Reduction Followed by Wet Scrubbing/Fluorescence Detection.

A portable chemical analysis system for monitoring ambient carbonyl sulfide (COS) was investigated for the first time. COS is paid attention to from the perspectives of photosynthesis tracer, breath diagnosis marker, and new process-use in the manufacture of semiconductors. Recently, the threshold level value of COS was settled at 5 ppm in volume ratio (ppmv) for workplace safety management. In this work, COS was converted to H2S by a small column packed with alumina catalyzer at 65 °C. Then, the H2S produced was collected in a small channel scrubber to react with fluorescein mercuric acetate (FMA), and the resulting fluorescence quenching was monitored using an LED/photodiode-based miniature detector. The miniature channel scrubber was re-examined to determine its robustness and easy fabrication, and conditions of the catalyzer were optimized. When the FMA concentration used was 1 μM, the limit of detection and dynamic range, which were both proportional to the FMA concentration, were 0.07 and 25 ppbv, respectively. Ambient COS in the background level and even contaminated COS in the nitrogen gas cylinder could be detected. If necessary, H2S was removed selectively by reproducible adsorbent columns. COS concentrations of engine exhaust were measured by the proposed method and by cryo-trap-gas chromatography-flame photometric detection, and the results obtained (0.5–5.9 ppbv) by the two methods agreed well (R2 = 0.945, n = 19). COS in ambient air and exhaust gases was successfully measured without any batchwise pretreatment.

Effect of Steel-Reinforced Grout Confinement on Concrete Square and Cylindrical Columns

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Unravelling an abandoned giant in Central Luconia Province, offshore Sarawak, Malaysia — Success story of Lang Lebah

In 1994, two exploration wells were drilled consecutively to explore for gas prospectivity in Lang Lebah, a Miocene carbonate buildup in the geologic province of Central Luconia located in the Sarawak Basin in Malaysia. High overpressure and operational problems prevented both wells from fully evaluating the target. Postdrill analysis concluded that Lang Lebah has limited potential due to poor reservoir quality, small gas column, and challenging drilling conditions. For these reasons, it was left dormant for 25 years. In 2016, new 3D broadband seismic acquisition and megamerge reprocessing of 3D seismic data sets followed by an integrated application of multidisciplinary workflows successfully derisked key petroleum system elements of the Lang Lebah structure, yielding a more optimistic view of its potential. A new well was justified at Lang Lebah and resulted in one of the major gas discoveries of 2019.

Optimisation of solvent recovery in two batch distillation columns of different size

The recovery of acetone from an aqueous industrial waste solvent mixture containing a small amount of dichloromethane is studied. This separation can be performed in a single, large enough batch distillation column. When the amount of the waste solvent mixture increases and exceeds the processing capacity of this column, either the excess of solvent must be incinerated, or the processing capacity must be increased. The incineration is very disadvantageous from both economic and environmental points of view. It is investigated whether capacity can be efficiently increased by applying an additional, much smaller column, which is already available in the plant. Dichloromethane is removed in fore-cuts from both columns. The charge of the larger column (Column2) consists of two main cuts obtained from two consecutive batches of Column1. High purity acetone is obtained in the main cut of Column2. The optimisation of both the single- and two-column processes is performed by a genetic algorithm coupled with a professional flow-sheet simulator. The objective function minimised is the specific energy demand of the production of acetone. The effects of the composition of the fresh feed on the optimal values of the parameters and of the objective function are studied: the specific energy demand changes favourably on the increase of water and the decrease of dichloromethane concentration. A response surface method is used to successfully predict the optimal operating parameters in the space of compositions studied. Each optimised case is evaluated from economic and environmental points of view, as well. For an average charge composition, also by considering recycling of the residues of both columns, the weekly profit is by 12% higher and the CO2 emission is by more than 20% lower compared to the single-column process. Moreover, the processing capacity is increased by about 30%. It is shown in our work that it is worth applying a second, possibly smaller batch distillation column available in the plant before a larger one in order to increase the processing capacity.

Use of rapid small-scale column tests for simultaneous prediction of phosphorus and nitrogen retention in large-scale filters

Rapid small-scale column tests (RSSCTs) have been previously used to predict the effluent concentration of a single nutrient in large filters with good accuracy. However, in drainage waters originating from heavy textured soils, where there is a need for in-ditch filters to retain both dissolved reactive phosphorus (DRP) and ammonium (NH4) simultaneously, the suitability of a RSSCT approach to model both parameters must be proved. In this study, a decision support tool was used to identify appropriate media that may be placed in filters for the removal of DRP and NH4. The selected media for this study were sand and zeolite. Both media were placed in acrylic tubes each with an internal diameter of 0.01 m and with lengths ranging from 0.1 to 0.4 m, and their performance for simultaneous removal of DRP and NH4 (1 mg DRP and NH4-N L−1) from water was evaluated. The data generated from the RSSCTs were used to model DRP and NH4 removals in 0.4 m-long laboratory columns of internal diameter 0.1 m, which had the same media configuration as the small columns and were operated using the same influent concentrations. The developed model successfully predicted the effluent concentration of both the DRP and NH4-N from the large columns. This indicates using RSSCTs to model the performance of filters will produce substantial savings in operational, financial and labour costs, without affecting the accuracy of model predictions.

Fine configuration of the dural fibrous network and the extradural neural axis compartment in the jugular foramen: an epoxy sheet plastination and confocal microscopy study.

The extradural neural axis compartment (EDNAC) is an adipovenous zone that is located between the meningeal (ML) and endosteal (EL) layers of the dura mater and has been minimally investigated in the jugular foramen (JF) region. In this study, the authors aimed to explore the fine architecture of the EDNAC within the JF and evaluate whether the EDNAC can be used as a component for JF compartmentalization. A total of 46 cadaveric heads (31 male, 15 female; age range 54-96 years) and 30 dry skulls were examined in this study. Twelve of 46 cadaveric heads were plastinated as a series of transverse (7 sets), coronal (3 sets), and sagittal (2 sets) slices and examined using stereomicroscopy and confocal microscopy. The dural entry points of the JF cranial nerves were recorded in 34 cadaveric skulls. The volumes of the JF, intraforaminal EDNAC, and internal jugular vein (IJV) were quantified. Based on constant osseous landmarks, the JF was subdivided into preforaminal, intraforaminal, and subforaminal segments. The ML-derived fascial sheath along the anteromedial wall of the IJV demarcated the "venous portion" and the "EDNAC portion" of the bipartite JF. The EDNAC did not surround the intraforaminal IJV and comprised an ML-derived dural fibrous network and an adipose matrix. A fibrovenous curtain subdivided the intraforaminal EDNAC into a small anterior column containing cranial nerve (CN) IX and the anterior condylar venous plexus and a large posterior adipose column containing CNs X and XI. In the intraforaminal segment, the IJV occupied a slightly larger space in the foramen (57%; p < 0.01), whereas in the subforaminal segment it occupied a space of similar size to that of the EDNAC. Excluding the IJV, the neurovascular structures in the JF traverse the dural fibrous network that is dominant in the foraminal EDNAC. The results of this study will contribute to anatomical knowledge of the obscure yet crucially important JF region, increase understanding of foraminal tumor growth and spread patterns, and facilitate the planning and execution of surgical interventions.

Differentiating between adsorption and biodegradation mechanisms while removing trace organic chemicals (TOrCs) in biological activated carbon (BAC) filters

Efficient adsorption of certain trace organic chemicals (TOrCs) present in secondary treated municipal wastewater treatment plant (WWTP) effluents onto granular activated carbon (GAC) has already been demonstrated at lab- and full-scale. Due to high organic matter concentrations in WWTP effluents, GAC filters eventually develop a biofilm and turn into biological activated carbon filters (BAC), where removal of organic compounds is governed by biodegradation as well as by adsorption. However, determining TOrC breakthrough by conducting a long-term BAC column experiment to discern between the removal mechanisms is not possible due to competition for adsorption sites, fluctuating water quality, and other variables. Therefore, a rapid small scale column test (RSSCT) was conducted to determine the contribution of adsorption for select chemicals at 10,000 bed volumes treated (BVT). These results were then used in the pore surface diffusion model (PSDM) to model adsorption behavior at 40,000 BVTs. Pseudo-Freundlich K values obtained from the PSDM model were compared with K values obtained from an integral mass balance calculation. This comparison revealed that the modeling was most accurate for moderately to poorly adsorptive compounds. In comparing RSSCT results to long-term BAC columns, the modeling approach best predicted BAC removal of well adsorbing compounds, such as atenolol, trimethoprim, metoprolol, citalopram, and benzotriazole. However, differences in predicted vs observed BAC removal for the removals of venlafaxine, tramadol and carbamazepine revealed that BAC adsorption capacity was not yet exhausted for these compounds. Therefore, a comparison was not possible. The approach would be improved by operation at longer EBCT and improved calculation of compound fouling indices.

Utilization of Biomass Fly Ash for Improving Quality of Organic Dye-Contaminated Water.

Development of innovative methodologies to convert biomass ash into useful materials is essential to sustain the growing use of biomass for energy production. Herein, a simple chemical modification approach is employed to functionalize biomass fly ash (BFA) with 3-aminopropyltriethoxy silane (APTES) to develop an inexpensive and efficient adsorbent for water remediation. The amine-functionalized BFA (BFA–APTES) was fully characterized by employing a range of characterization techniques. Adsorption behavior of BFA–APTES was evaluated against two anionic dyes, namely, alizarin red S (ARS) and bromothymol blue (BTB). In the course of experimental data analysis, the computation tools of data fitting for linear and nonlinear form of Langmuir, Freundlich, and the modified Langmuir–Freundlich adsorption isotherms were used with the aid of Matlab R2019b. In order to highlight the misuse of linearization of adsorption models, the sum of the squares of residues (SSE) values obtained from nonlinear models are compared with R2 values obtained from the linear regression. The accuracy of the data fitting was checked by the use of SSE as an error function instead of the coefficient of determination, R2. The dye adsorption capacity of BFA–APTES was also compared with the nonfunctionalized BFA. The maximum adsorption capacities of BFA–APTES for ARS and BTB dye molecules were calculated to be around 13.42 and 15.44 mg/g, respectively. This value is approximately 2–3 times higher than the pristine BFA. A reasonable agreement between the calculated and experimental values of qe obtained from the nonlinear form of kinetic models verified the importance of using equations in their original form. The experimentally calculated thermodynamic parameters including molar standard Gibbs free energy (ΔadGm0) and molar standard enthalpy change (ΔadHm0) reflected that the process of adsorption of dye molecules on the BFA–APTES adsorbent was spontaneous and exothermic in nature. Moreover, the used BFA–APTES adsorbent could be regenerated and reused for several cycles with significant dye adsorption capacity. The remediation capability of the BFA–APTES adsorbent against ARS dye was also demonstrated by packing a small column filled with the BFA–APTES adsorbent and passing a solution of ARS through it. Overall, we provide a simple and scalable route to convert BFA into an efficient adsorbent for water remediation applications.

Adsorption mechanisms of PFOA onto activated carbon anchored with quaternary ammonium/epoxide-forming compounds: A combination of experiment and model studies

When wood-based activated carbon was tailored with quaternary ammonium/epoxide (QAE) forming compounds (QAE-AC), this tailoring dramatically improved the carbon's effectiveness for removing perfluorooctanoic acid (PFOA) from groundwater. With favorable tailoring, QAE-AC removed PFOA from groundwater for 118,000 bed volumes before half-breakthrough in rapid small scale column tests, while the influent PFOA concentration was 200 ng/L. The tailoring involved pre-dosing QAE at an array of proportions onto this carbon, and then monitoring bed life for PFOA removal. When pre-dosing with 1 mL QAE, this PFOA bed life reached an interim peak, whereas bed life was less following 3 mL QAE pre-dosing, then PFOA bed life exhibited a steady rise for yet subsequently higher QAE pre-dosing levels. Large-scale atomistic modelling was used herein to provide new insight into the mechanism of PFOA removal by QAE-AC. Based on experimental results and modelling, the authors perceived that the QAE's epoxide functionalities cross-linked with phenolics that were present along the activated carbon's graphene edge sites, in a manner that created mesopores within macroporous regions or created micropores within mesopores regions. Also, the QAE could react with hydroxyls outside of these pore, including the hydroxyls of both graphene edge sites and other QAE molecules. This latter reaction formed new pore-like structures that were external to the activated carbon grains. Adsorption of PFOA could occur via either charge balance between negatively charged PFOA with positively charged QAE, or by van der Waals forces between PFOA's fluoro-carbon tail and the graphene or QAE carbon surfaces.

Effective removal of perfluorooctanoate from groundwater using quaternary nitrogen-grafted granular activated carbon

In this study, a quaternary nitrogen-grafted activated carbon (SNQ) was synthesized to remove perfluorooctanoate (PFOA) from a groundwater source. Batch isotherm tests and rapid small scale column tests (RSSCTs) were used to evaluated the performance of these variants in removing PFOA from groundwater. When processing groundwater that had been spiked with 200 ng/L PFOA, the SNQ exhibited 201,000 BV to 60 % breakthrough. This was 1.6 times higher than for the pristine SAC (128,000 BV). The longer bed life was attributed to the tailored carbon’s enhanced positively charged surface properties, which were monitored for this SNQ adsorbent by means of X-Ray Photoelectron Spectrometer, Scanning Electron Microscopy and Incremental surface charge titration analysis. Kinetics and isotherm tests show that the SNQ exhibited higher adsorption rate and adsorption capacity than the pristine subbituminous coal based activated carbon (SAC); and this was attributed to SNQ’s retained pore structure, high quaternary nitrogen ratio (0.89 %) and positive charge (0.47 meq/g). Moreover, the positively charged quaternary nitrogen groups onto the SNQ strongly attracted PFOA and lead to higher effective diffusion rates (12.6×10−10 m2/s). In order to test the nature of PFOA sorption, the authors employed a dynamic regeneration protocol using ethanol as an organic solvent; and this protocol restored 73 % PFOA adsorption capacity of the SNQ. In light of this tailored SNQ carbon’s high PFOA adsorption capacity and regenerability, we anticipated this quaternary nitrogen-grafted activated carbon could serve as an excellent adsorbent for PFOA removal from groundwater.

Simultaneous determination of seven metabolites of organophosphate esters and 8-hydroxy-2'-deoxyguanosine in urine by high-performance liquid chromatography-tandem mass spectrometry with homemade mixed column purification

A method based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) with a small homemade mixed column was developed for the simultaneous determination of seven metabolites of organophosphate esters (OPEs) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), an DNA oxidative damage marker, in urine. The urine samples were extracted by acetonitrile and enriched by the self-made column. All the samples were separated by gradient elution with acetonitrile-0.2% (v/v) ammonia solution, and then analyzed by an electrospray ionization source in negative ion multiple reaction monitoring mode. The results showed that the eight targets had good linearities in the range of 0.1-200 μg/L. The recoveries of the seven metabolites of OPEs and 8-OHdG in urine samples were in the ranges of 52.36% to 114.56% and 88.63% to 97.72%, respectively. The established method was successfully applied for the determination of the abovementioned eight target compounds in real urine samples, with the mass concentrations of the seven metabolites of OPEs and 8-OHdG being 6.24-46.07 μg/L and 5.90-16.71 μg/L, respectively. In addition, significant correlations were found between 8-OHdG and the total content of the seven metabolites of OPEs. The established method is simple, sensitive, accurate, and reproducible, and it provides reliable technical support for a more comprehensive evaluation of the level of human exposure to OPEs and the resulting health hazards.

Evaluation of Assouline–Or Adjusted Model to Express Soil Drainage Curve

The objectives of this research are prediction of soil drainage curve using Assouline and Or (2014) adjusted soil drainage model and comparison of the predicted results with experimental data on small and large scales. This research is conducted for 18 small soil columns under different salinity level of irrigation water using different scenarios. In scenario A, water from saturated water and water of 0.1 (A-1) and 15 (A-2) bar matric head assumed as the mobile water, D∞, and input to Assouline and Or model to estimate weighted average of hydraulic conductivity, Km with fitting. In scenario B, Km is computed using water characteristic curve and D∞ is obtained using fitted model. Finally, in scenario C, D∞ and Km are predicted using fitted model. All experiments were repeated in the presence of plant for small soil columns and columns with 2.7 m depth as well. Results showed that the model prediction is influenced by irrigation water salinity, study time and depth scales. However, soil and water physical properties and their interactions can partially explain the results and the flexibility of Assouline and Or model is appropriate, we suspected to the validity of physical meaning of model parameters and, the certainty of model predictions for the field capacity, FC, concept.

Analysis of 2-aminopyridine labeled glycans by dual-mode online solid phase extraction for hydrophilic interaction and reversed-phase liquid chromatography

Quantitative analysis of glycans released from glycoproteins using high-performance liquid chromatography (HPLC) requires fluorescent tag labeling to enhance sensitivity and selectivity. However, the methods required to remove large amounts of excess labeling reagents from the reaction mixture are time-consuming. Furthermore, these methods, including solvent extraction and solid phase extraction (SPE), often impair quantitative analysis. Here, we developed an online sample cleanup procedure for HPLC analysis of 2-aminopyridine (AP)-labeled glycans using a six-port/two-way valve and two small columns: one packed with a strong cation exchange resin (SCX) and the other comprising ODS silica gel. AP-labeled glycans delivered from an injection port were separated from excess AP by passing through an SCX column (4.6 mm i.d., 1 cm long) regulated to 40°C. The AP-labeled glycans were trapped on an ODS column (4.6 mm i.d., 1 cm long) to further separate them from inorganic contaminants. By changing the valve position after 2 min to connect the ODS column to an analysis column, AP-labeled glycans trapped in the ODS column were eluted with an acetonitrile-containing eluent followed by hydrophilic interaction liquid chromatography (HILIC) separation on an amide column or reversed-phase mode separation on a C30 column. This method was successfully used to analyze N-linked glycans released from several glycoprotein samples.

Acoustic Affinity Cell Selection: a non-paramagnetic scalable technology for T cell selection from unprocessed apheresis products

Background & Aim Acoustic Cell Processing is a unique acousto-fluidics platform technology for minimal shear manipulation of cells using ultrasonic standing waves. The platform has broad applications in the field of cell and gene therapy, e.g., cell concentration and washing, cell culturing, microcarrier/cell separation, acoustic affinity cell selection and label-free cell selection. The acoustic radiation force exerted by the ultrasonic standing wave on the suspended cells in combination with fluid drag forces and gravitational forces is used to manipulate the cells and achieve a certain cell processing unit operation, e.g., separate, concentrate, or wash. The technology is single-use, continuous, and can be scaled up, down or out. It therefore allows for a flexible and modular approach that can be customized to process a desired cell count, cell culture volume or cell concentration within a given required process time. Utilizing its proprietary multi-dimensional standing wave platform, MilliporeSigma has been developing the Acoustic Affinity Cell Selection (AACS) system for closed and automated Cell and Gene Therapy manufacturing, e.g., CAR-T immunocellular therapies. The AACS technology is a scalable acoustic affinity cell selection method using acoustic (non-paramagnetic) affinity beads for positive or negative cell selection. A multi-dimensional acoustic standing wave is then used to separate the affinity bead-cell complexes from the unbound cells, thereby completing the process of a negative or positive cell selection. Methods, Results & Conclusion In this work the AACS system has been used to capture CD4+ and CD8+ cells from unprocessed apheresis products. The AACS column and acoustic section (Fig. 1A) allow for a continuous flow of the initial cell population (pre-labeled with biotinylated antibodies) while acoustically retaining the acoustic affinity particles in the column. The affinity particles are functionalized with Neutravidin and thus capture the target cells that are kept inside the column, while the non-target cells are washed out of the column. The small scale 5mL column has a total target cell capture capacity of 1.8B cells (60mL Leukopak volume), of which 83% are retained in the column at a 92% purity (Fig. 1B). The AACS scale up system can process a full apheresis product (300-450mL) in less than 2h.

Grouping of Retention Index on Gas Chromatography using Cluster Analysis

Retention index data consisting of 146 compounds commonly found in fuels are used to analyze the level of a psycho-chemical property similarity with cluster analysis methods. Cluster analysis is applied based on the temperature and column dependencies. The results show that the retention index was divided into four groups. The first group consists of benzene and cycloalkanes. The retention index of the compound shows high-temperature dependence and dependence on small column polarity. The second group consists of aromatic compounds and compounds that contain N, S, O. The retention index of these compounds shows dependence on temperature and polarity of large columns. The third group consists of aromatic compounds and hydrocarbons. The retention index of hydrocarbon compounds shows temperature dependence smaller than N, S, O. compounds and also the dependence on small column polarity. And the fourth group consists of only two compounds namely n-Hentriacontane and chrysene. The retention index of the two compounds shows a significant temperature dependence.

Application of analytical solution of advection-dispersion-reaction model to predict the breakthrough curve and mass transfer zone for the biosorption of heavy metal ion in a fixed bed column

This work aims to apply an analytical solution of the contaminant transport model to predict the sorption's breakthrough curve and mass transfer zone of single component heavy metal ions using green macroalga, Caulerpa lentillifera, in a small scale cylindrical fixed-bed columns. The model was represented in a form of differential equation with two model constants which were diffusion coefficient (Deff) and linear sorption coefficient (kp). The linear isotherm could be well described for the sorption at a lower range of sorbate concentration while the Langmuir isotherm was suitable for a wider range of concentration. The reference set of experiments (with a bed depth of 4cm and a flow rate of 6mL/min) were used for calibrating the model to obtain the model constants. The model could be well applied to predict the breakthrough curve of varying bed depth from the reference set of experiments for the sorption of Pb2+ and Cd2+. However, the model predicts slower breakthrough time than that in the experimental results when the flow rate is changed from the reference set of experiments. Three-dimensional plots and contour plots were generated to analyze the sorption behavior of metal ion in the column. The relationship between bed depth and service time (BDST) obtained from the model in this work is not linear, as often seen in the general BDST model. Both advection and dispersion processes govern the sorbate transport in the column. The mass transfer zone (MTZ) is continuously expanding along with the column length in this study. The relationship between MTZs and bed depth is also not linear.

Unidirectional en masse larval dispersal of blow flies (Diptera: Calliphoridae)

Decomposition of carrion is a complex ecological process wherein nutrients and energy are recycled in the environment. After feeding but prior to pupation, blow fly larvae disperse from decomposing carrion, presumably to escape unfavorable microsite conditions or perhaps predation. By leaving the immediate area, larvae are effectively transporting carrion-derived nutrients throughout the ecosystem. This dispersal is generally characterized as individual-based and moving randomly from the carcass in every direction, however, non-random, en masse maggot dispersal has been documented at least twice. Here, we report another incidence of en masse blow fly larval dispersal traveling due east in a small column. At approximately 2 m, the column stopped its unidirectional path and dispersed in a radial, 360° pattern. A subsample of 5 larvae was collected, returned to the lab, and identified as Lucilia coeruleiviridis, a common blow fly often involved in carrion decomposition in nature. These observations contribute to an increasing body of evidence that migrating fly larvae do not always disperse randomly, which may have important implications for the dispersal of carrion-derived nutrients as well as interactions with blow fly predators.