Increasing Column Height Research Articles

Synthesis of Glue-Free NaA Zeolite Granules from Natural Kaolin for the Adsorption of Pb(II) Ions in Aqueous Solution Using a Fixed-Bed Column Study.

NaA zeolite-coated metakaolin granules (MKG@NaA) were successfully synthesized from kaolin mineral by primary growth in the hydrothermal reaction without using glue or a seed crystal. The XRD and SEM analysis results revealed that a layer of NaA zeolite with a typical cubic shape and high crystallinity formed on the surface of kaolin granules. The obtained material was used as an adsorbent for lead metal ion Pb(II) adsorption studies in a fixed-bed column configuration. The operation factors such as the solution inflow rate, Pb(II) concentration, and column height were investigated. The results showed that the adsorption capacity of the material increased with increasing column height and initial concentration of the influent and decreased with increasing flow rate. With the test parameters at the Pb(II) concentration of 100 mg·L–1, the adsorbent bed height of 8.1 cm, and the inflow rate of 2.5 mL·min–1, the lead ion adsorption capacity was 118.5 mg·g–1. The Thomas, Yoon–Nelson, and bed depth service time models were applied to describe the breakthrough curves for Pb(II) ion removal by a fix-bed column using the MKG@NaA absorbent and to predict the column performance under different experimental conditions with good linearity (R2 > 0.95).

Investigation of the transport characteristics of Pb(II) in sand-bone char columns.

Pb(II) leakage from batteries, dyes, construction materials, and gasoline threaten human health and environmental safety, and suitable adsorption materials are vitally important for Pb(II) removal. Bone char is an outstanding adsorbent material for water treatment, and the effectiveness in Pb(II) removing need to be verified. In this paper, the transport characteristics of Pb(II) in columns filled with a sand and bone char mixture were studied at the laboratory scale, and the influences of the initial concentration, column height, inlet flow rate, and competing ion Cu(II) on Pb(II) adsorption and transport were analyzed. The Thomas and Dose-Response models were used to predict the test results, and the mechanisms of Pb(II) adsorption on bone char were investigated. The results showed that the adsorption capacity of the bone char increased with increasing column height and decreased with increasing initial Pb(II) concentration, flow rate, and Cu(II) concentration. The maximum adsorption capacity reached 38.466 mg/g and the saturation rate was 95.8% at an initial Pb(II) concentration of 200 mg/L, inlet flow rate of 4 mL/min, and column height of 30 cm. In the competitive binary system, the higher the Cu(II) concentration was, the greater the decreases in the breakthrough and termination times, and the faster the decrease in the Pb(II) adsorption capacity of the bone char. The predicted results of the Dose-Response model agreed well with the experimental results and were significantly better than those of the Thomas model. The main mechanisms of Pb(II) adsorption on bone char include a surface complexation reaction and the decomposition-replacement-precipitation of calcium hydroxyapatite (CaHA). Based on selectivity, sensitivity, and cost analyses, it can be concluded that bone char is a potential adsorbent for Pb(II)-containing wastewater treatment.

Removal of Cu(II) by Fixed-Bed Columns Using Alg-Ch and Alg-ChS Hydrogel Beads: Effect of Operating Conditions on the Mass Transfer Zone.

The removal of Cu(II) ions from aqueous solutions at a pH of 5.0 was carried out using fixed-bed columns packed with alginate-chitosan (Alg-Ch) or alginate-chitosan sulfate (Alg-ChS) hydrogel beads. The effect of the initial Cu(II) concentration, flow rate, pH, and height of the column on the amount of Cu removed by the column at the breakpoint and at the exhaustion point is reported. The pH of the solution at the column’s exit was initially higher than that at the entrance, and then decreased slowly. This pH increase was attributed to proton transfer from the aqueous solution to the amino and COO− groups of the hydrogel. The effect of operating conditions on the mass transfer zone (MTZ) and the length of the unused bed (HLUB) is reported. At the lower flow rate and lower Cu(II) concentration used, the MTZ was completely developed and the column operated efficiently; by increasing column height, the MTZ has a better opportunity to develop fully. Experimental data were fitted to the fixed-bed Thomas model using a non-linear regression analysis and a good correspondence between experimental and Thomas model curves was observed.

Dynamic Adsorption of Sulfamethoxazole from Aqueous Solution by Lignite Activated Coke.

In this paper, lignite activated coke was used as adsorbent for dynamic column adsorption experiments to remove sulfamethoxazole from aqueous solution. The effects of column height, flow rate, initial concentration, pH and humic acids concentration on the dynamic adsorption penetration curve and mass transfer zone length were investigated. Results showed penetration time would be prolonged significantly by increasing column height, while inhibited by the increasement of initial concentration and flow rate. Thomas and Yoon-Nelson model and the Adams-Bohart model were used to elucidate the adsorption mechanism, high coefficients of R2 > 0.95 were obtained in Thomas model for most of the adsorption entries, which revealed that the adsorption rate could probably be dominated by mass transfer at the interface. The average change rates of mass transfer zone length to the changes of each parameters, such as initial concentration, the column height, the flow rate and pH, were 0.0003, 0.6474, 0.0076, 0.0073 and 0.0191 respectively, revealed that column height may play a vital role in dynamic column adsorption efficiency. These findings suggested that lignite activated coke can effectively remove sulfamethoxazole contaminants from wastewater in practice.

Rotational Behavior of Column Footing Joint and Its Effect on the Dynamic Characteristics of Traditional Chinese Timber Structure

Chinese heritage timber buildings are of high historical and cultural values. The column footing joint is an important connection influencing the structural performance under dynamic load. The moment‐rotation relationship of a column footing joint is studied and the effects of vertical load and ratio of column height to diameter on its rotational behavior are analyzed. A spring elements model is proposed to simulate the column footing joint and its stiffness matrix can be simplified to include only one stiffness parameter K with some assumptions. A component‐based finite‐element model of a timber pavilion is then developed to investigate the effect of rotational stiffness on the structural dynamic characteristics. Results show that a heavier vertical load may lead to larger ultimate moment capacity of the joint. The initial rotational stiffness and ultimate moment capacity decrease with increasing column height to diameter ratio. The modal frequency of the structure studied changes remarkably when the rotational stiffness K varies from 104 to 108 N▪m/rad. The column footing joints should be regarded as semirigid connections in the structural dynamic analysis. A field experiment was also conducted to further demonstrate that the rotational stiffness of column footing joint has notable influence on the dynamic characteristics of traditional Chinese timber structure.

Upscaling Capillary Pressure–Saturation Functions Using Different Reference Pressure Elevations

Core Ideas The BC‐vG Upscaler predicts the drainage of porous media of different heights. The default reference pressure elevation (RPE) is the middle of the porous medium. Predicted drainage functions deviate from observed functions as height increases. A top RPE improves accuracy of predicted drainage functions regardless of height. Choice of reference pressure elevation (RPE) on average effective saturation–capillary pressure functions, 〈〉(ψ), was investigated for monotonic drainage of homogeneous porous media. Nine columns of Flint sand with heights ranging from 4.3 to 55.0 cm were prepared. Measured 〈〉(ψ) functions were determined gravimetrically using the hanging water column method. Predicted 〈〉(ψ) functions were obtained by upscaling point function parameters determined by neutron radiographic imaging of a single drainage experiment. Bottom and midpoint RPEs resulted in the inaccurate parameterization of 〈〉(ψ) functions for tall columns. A top RPE produced accurate upscaled functions for all column heights. To evaluate the overall performance of this RPE, observed effective saturations for the nine columns were linearly regressed against predicted values. The resulting best‐fit model (slope = 0.98; intercept = 0.03; R2 = 0.98) corresponded closely to a 1:1 line. The van Genuchten (vG) α and n parameters for the observed and predicted 〈〉(ψ) functions decreased with increasing column height. A power model explained >95% of the variance in the predicted vG parameters and between 69 and 78% of the variance in the observed vG parameters. The lower R2 values for the observed parameter models were attributed to experimental variation among the nine columns, whereas the predicted parameter models were upscaled from a single column. Despite these differences, the magnitudes and height dependencies of the observed and predicted average vG parameters were similar. For tall columns, the RPE should be established at the top for drainage experiments and at the bottom for wetting experiments.

Deacidification of organic liquid products by fractional distillation in laboratory and pilot scales

This work aims to investigate the de-acidification of organic liquid products, obtained by catalytic cracking of palm oil (Elaeis guineensis Jacq) using Na2CO3 as catalyst, by fractional distillation. The distillation of OLP carried out in laboratory, using columns of different heights with and without reflux, and in pilot scale. OLP and distillation fractions physicochemical characterized for density, kinematic viscosity, acid value, saponification value, refractive index, ester index, free fatty acids, flash point, and copper strip corrosion. The OLP analyzed by GC–MS and FT-IR, and light diesel-like fractions by FT-IR, NMR, and GC–MS. The experiments carried out in laboratory scale with and without reflux showed biofuels (distillates) yields between 62.15 and 76.41% and 71.65 and 89.44% (wt.), respectively, while that in pilot scale was 32.68% (wt.). For the experiments in laboratory scale, the yields of distillates decrease exponentially with column height, with and without reflux, while those of bottoms products increase exponentially. In addition, the yields of distillates and gas increase with increasing Na2CO3 content, while that of bottom products decrease. The yield of light diesel-like fractions, with and without reflux ranged between 48.82 and 63.18, and 20.23 and 21.43% (wt.), respectively. The column height had no significant effect on the density of distillation fractions, with and without reflux. The densities of gasoline, kerosene, and light diesel with reflux, superpose exactly those of kerosene, light diesel, and heavy diesel without reflux. The kinematic viscosity of distillation fractions decreases with increasing column height for the experiments with and without reflux, while the acid values decrease. For the distillation experiments in pilot scale, the acid values of gasoline, kerosene, and light diesel-like fractions were 0.33, 0.42, and 0.34mg KOH/g. FT-IR of distillation fractions in pilot scale and NMR of light diesel-like fraction in laboratory scale, column height of 50cm, under reflux identified the presence of aliphatic hydrocarbons and the absence of carbonyl groups. The GC–MS analysis identified in OLP composition 92.84% (area.) hydrocarbons and 7.16% (area.) oxygenates. The light diesel-like fraction contains 100% hydrocarbons with an acid value of 0.34mg KOH/g, density of 0.7862g/cm3, and kinematic viscosity of 1.52mm2s−1, proving the feasibility of OLP de-acidification by fractional distillation.

Voronoï analysis of bubbly flows via ultrafast X-ray tomographic imaging

Although clustering of bubbles plays a significant role in bubble column reactors regarding the heat and mass transfer due to bubble–bubble and flow field interactions, it has yet to be fully understood. Contrary to flows in bubble columns, most literature studies on clustering report numerical and experimental results on dilute or micro-bubbly flows. In this paper, clustering of bubbles in a cylindrical bubble column of 100 mm diameter is experimentally investigated. Ultrafast X-ray tomographic imaging is used to obtain the bubble positions within a hybrid Eulerian framework. By means of Voronoi analysis, the clustering behavior of bubbles is investigated. Experiments are performed with different superficial gas velocities, where Voronoi diagrams are constructed at several column heights. From the PDFs of the Voronoi diagrams, it is shown that the bubble structuring in terms of Voronoi cell volumes develops slower than the bubble size distribution. The latter reaches a steady state earlier with increasing column height. The measured PDFs are compared with the PDF of randomly distributed points, which showed that the amount of bubbles as part of clusters (Voronoi cells < $$V/\overline{V}_\mathrm{{cluster}}$$ ) as well as bubbles as part of voids (Voronoi cells > $$V/\overline{V}_\mathrm{{void}}$$ ) increases with the superficial gas velocity. It is found that all experiments have an approximate cluster limit $$V/\overline{V}_\mathrm{{cluster}}$$ of 0.63, while the void limit $$V/\overline{V}_\mathrm{{void}}$$ varies between 1.5 and 3.0.

The effect of object size on the sensitivity of single photon emission computed tomography: comparison of two CZT cardiac cameras and an Anger scintillation camera.

BackgroundHeart sizes vary greatly across the spectrum of patients referred for myocardial perfusion imaging. We therefore performed a phantom study to explore under controlled circumstances how count rates change when different volumes containing the same amount of activity are scanned. Two dedicated cadmium-zinc-telluride cameras, the D-SPECT (Spectrum Dynamics, Caesarea, Israel) and Discovery 530c (D530c, GE Healthcare, Haifa, Israel), and the conventional SPECT Anger (A-SPECT, GE Healthcare, Haifa, Israel) camera are included in the study.MethodsDifferent heart sizes were represented by syringes of various column heights mimicking a range of cardiac diameters. Syringes with fixed activity were scanned at five different volumes by successively adding non-radioactive water to the syringes. This procedure was repeated five times on each of the three cameras. Raw count rates were recorded for each scan to determine whether count rates changed with syringe column height.ResultsUsing mixed-effect regression modeling, a linear relationship was found between count rate and water column height. For the D-SPECT, D530c, and A-SPECT, the changes in count rate for each centimeter increase in water column height were −1.75, +0.28, and −0.022 kilocounts per min per MBq, respectively (95% confidence intervals −1.89 to −1.61, 0.19 to 0.36, and −0.035 to −0.009); all effects are significantly different from each other and significantly different from zero. Average coefficients of variation were 0.080, 0.028, and 0.009.ConclusionsThe D-SPECT demonstrated a significant progressive increase in count rate related to decreasing size of the imaged object. D530c count rate increased slightly with increasing column height. The Anger SPECT showed minimally increased count rates with decreasing column height, an order of magnitude smaller than the D-SPECT based on their relative coefficients of variation.Electronic supplementary materialThe online version of this article (doi:10.1186/s40658-014-0097-5) contains supplementary material, which is available to authorized users.

Effect of the column height on the performance of liquid–solid fluidized bed for the separation of coarse slime

A liquid–solid fluidized bed separator, used for the separation of coarse slime, was developed. Test particles sized in the range from 0.25 to 0.5, 0.5 to 1.0, and 0.25 to 1.0mm were separated in the liquid–solid fluidized bed. Beds with column heights of 1200, 1500, and 1800mm were tried. The clean coal and the tailings were subsequently analyzed by float–sink testing. The results showed that the ash and yield of clean coal both decreased with increasing column height, for all three size fractions, and that the ash of the clean coal obtained from tests on the broader size fraction was less than that from the narrower sized fractions. The separation density decreased with increasing column height. The lowest E value was seen for a column height of 1500mm, for which conditions the separation density was 1.45g/cm3. The E value was 0.084 for the 0.25–0.5mm fraction but the corresponding separation density was 1.48g/cm3, and the E value 0.089, for the broader 0.25–1.0mm fraction.

Continuous Separation of Proteins by Using Colloidal Gas Separation and Nonionic Surfactant

Separation of protein by using colloidal gas aphrons (CGAs) is a promising method for removing organic materials from an aqueous solution. In this study, the continuous separation of lysozyme was carried out in a flotation column by using a CGA. The mechanism of adsorption of lysozyme on the CGA and the mass transfer from lysozyme to CGA were investigated. It was found that the adsorption of lysozyme on the CGA followed the Langmuir adsorption isotherm at a lysozyme volumetric flow rate of 2.37 mL/s. In the study of mass transfer, the overall mass transfer coefficient increased with the lysozyme and CGA volumetric flow rates, but decreased with increasing column height. The percentage of protein recovery increased with the lysozyme and CGA volumetric flow rates, column height, and residence time.

Calculation of CO 2 column heights in depleted gas fields from known pre-production gas column heights

Depleted gas fields have been identified as potential targets for CO 2 storage. In order to maximise storage capacity, a target field must be deep enough to ensure that the CO 2 is in a dense phase (either liquid or supercritical). Accurate assessment of the storage capacity also requires an estimation of the amount of CO 2 that can be safely stored beneath the reservoir seal which can be estimated in several ways. In this paper we develop a methodology to convert known pre-production gas column heights into CO 2 column heights in order to estimate storage capacities. Several authors have correctly identified that the differences in interfacial tension and wettability act to reduce the threshold capillary entry pressure for CO 2 compared to natural gas, consequently reducing column height estimates. However, under reservoir conditions the density of CO 2 is substantially higher than natural gas so the buoyancy force on the seal for a fixed column height is much lower for dense phase CO 2 increasing column height estimates; we investigate the effects of this trade off on storage estimates and apply it to a typical dataset, in this case the UK North Sea.

The best column number for enrichment of heavy water in thermal-diffusion columns of countercurrent-flow Frazier scheme with total sum of column height fixed

The effect of column number N and the same column height h of each thermal-diffusion column, on the Frazier scheme performance with total sum of column height ( L = Nh) fixed, has been investigated. The equations, which may be employed to predict the optimal number of columns (generally not integers) for the maximum performance are derived. Accordingly, the best number of columns, which are the integers nearest to, and small than the optimal column numbers, are obtained for practical applications. Considerable improvement in performance is obtainable if the scheme is constructed with the best number of thermal-diffusion columns, instead of using a single column with column height L ( N = 1, h = L). This is because that increasing column height in a thermal-diffusion column, though increasing the performance, will decrease the increment in performance, and finally the performance reaches a limiting value.

Monitoring the denitrification of wastewater containing high concentrations of nitrate with methanol in a sulfur-packed reactor.

Biological denitrification of high nitrate-containing wastewater was examined in a sulfur-packed column using a smaller amount of methanol than required stoichiometrically for heterotrophic denitrification. In the absence of methanol, the observed nitrate removal efficiency was only about 40%, and remained at 400 mg NO(3)(-)-N/l, which was due to an alkalinity deficiency of the pH buffer and of CO(2) as a carbon source. Complete denitrification was achieved by adding approximately 1.4 g methanol/g nitrate-nitrogen (NO(3)(-)-N) to a sulfur-packed reactor. As the methanol concentration increased, the overall nitrate removal efficiency increased. As influent methanol concentrations increased from 285 to 570, 855, and 1,140 mg/l, the value of Delta mg alkalinity as CaCO(3) consumed/Delta mg NO(3)(-)-N removed increased from -1.94 to -0.84, 0.24, and 0.96, and Delta mg SO(4)(2-) produced/Delta mg NO(3)(-)-N removed decreased from 4.42 to 3.57, 2.58, and 1.26, respectively. These results imply the co-occurrence of simultaneous autotrophic and heterotrophic denitrification. Sulfur-utilizing autotrophic denitrification in the presence of a small amount of methanol is very effective at decreasing both sulfate production and alkalinity consumption. Most of methanol added was removed completely in the effluent. A small amount of nitrite accumulated in the mixotrophic column, which was less than 20 mg NO(2)(-) -N/l, while under heterotrophic denitrification conditions, nitrite accumulated steadily and increased to 60 mg NO(2)(-) -N/l with increasing column height.

Stripping medium requirement in continuous countercurrent deodorization

AbstractA mathematical formula was derived that allows the stripping steam requirement of the countercurrent deodorization process to be calculated as a function of system pressure, vapor pressure of the pure volatile compound, initial and final volatiles contents, and the number of transfer units (an equipment parameter) of the countercurrent deodorizer. Just as in batch or cross‐flow deodorization systems, the steam requirement in countercurrent systems is proportional to the system pressure and inversely proportional to the vapor pressure of the pure volatile compound. Increasing the number of transfer units (for instance, by increasing column height) to more than two makes the countercurrent system require less steam than cross‐flow systems with a vaporization efficiency of 0.6. In addition, the short residence time in a countercurrent deodorization column minimizes side reactions and allows the deodorization temperature to be raised without generating unwanted by‐products such as trans‐isomers and/or oligomers of unsaturated fatty acids. The increased deodorization temperature increases the vapor pressure of the pure volatiles and leads to further savings in stripping medium and motive steam. Countercurrent deodorization systems therefore require less energy than cross‐flow deodorization systems and/or produce oil with fewer unwanted by‐products.

The Ottaviano eruption of Somma-Vesuvio (8000 y B.P.): a magmatic alternating fall and flow-forming eruption

The Ottaviano eruption occurred in the late neolithic (8000 y B.P.). 2.40 km 3 of phonolitic pyroclastic material (0.61 km 3 DRE) were emplaced as pyroclastic flow, surge and fall deposits. The eruption began with a fall phase, with a model column height of 14 km, producing a pumice fall deposit (LA). This phase ended with short-lived weak explosive activity, giving rise to a fine-grained deposit (L1), passing to pumice fall deposits as the result of an increasing column height and mass discharge rate. The subsequent two fall phases (producing LB and LC deposits), had model column heights of 20 and 22 km with eruption rates of 2.5 × 10 7 and 2.81 × 10 7 kg/s, respectively. These phases ended with the deposition of ash layers (L2 and L3), related to a decreasing, pulsing explosive activity. The values of dynamic parameters calculated for the eruption classify it as a sub-plinian event. Each fall phase was characterized by variations in the eruptive intensity, and several pyroclastic flows were emplaced (F1 to F3). Alternating pumice and ash fall beds record the waning of the eruption. Finally, owing to the collapse of a eruptive column of low gas content, the last pyroclastic flow (F4) was emplaced.

Improved gas'liquid contacting in co‐current flow

AbstractA new method of increasing interfacial area for gas‐liquid contacting in co‐current flow using screen packings has been evaluated in a 51/2‐in. I. D. column using CO2 chemisortpion in sodium hydroxide solution and CO2 physical desorption from water.The study investigated the effect of gas velocity (0.3‐2.7‐ft/sec.), liquid velocity (0.018‐0.1‐ft/sec), and of column height (0.67‐7.8‐ft.) on the interfacial area, a, and the physical desorption liquid phase mass transfer coefficient, KL.The two types of screen packing tested produced interfacial areas of 2 to 4 times that generated in an unpacked column. KL showed no effect of gas velocity but increased with liquid velocity, a and KL decreased with increasing column height. Generally, photographic evaluation gave unrealistically high values of a.