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This paper presents a study on the removal of CO2 gas from gas mixture (CO2/N2) of 14% CO2 using adsorption onto zeolite 13X in a fluidized bed at 298 K and 1 atm pressure. The effects of static bed height (5–25 cm) and rate of flow of the gas mixture (6–14 L/min) on the breakthrough time were studied. The desorption of CO2 was performed by absorbing the adsorbed CO2 molecules using NaOH solution (0.1 M). The absorption process which was accompanied with chemical reaction achieved two objectives. The first was converting CO2 gas into a valuable substance (Na2CO3) which could be used in many industries. The second was the storage of CO2 gas in what was called a chemical carrier which could emit the gas when it was needed. The effect of static bed height (5–25 cm) on the absorption process in the fluidized bed was also studied. For the adsorption process, the results showed that the breakthrough time increased with decreasing the flow rate but with increasing the static bed height. In the desorption process, the total amount of absorbed CO2 molecules was 396 mg, achieving a recovery of 90.8% at 5 cm static bed height. HIGHLIGHTS: Studying the adsorption in a fluidized bed. Using breakthrough curve to estimate the adsorbed amount of CO2. Studying the effects of operational parameters on the breakthrough time. Performing the desorption by absorption process. Recovering the adsorbed CO2 molecules. [ABSTRACT FROM AUTHOR]

The present work analyzes the behavior of an activated carbon fabricated from almond shells for the removal of cationic dyes (methylene blue, MB, and malachite green, MG) by adsorption from aqueous solutions. The carbonized precursor was activated with KOH at a 1:2 (w/w) ratio with the objective of increasing both the surface area and the pore volume. Both non-activated and activated carbon were characterized in different aspects of interest in dye adsorption studies (surface structure, point of zero charge, specific surface area, and pore size distribution). The effect of the dye's initial concentration and adsorbent dosage on dye removal efficiency and carbon adsorption capacity was studied. Adsorption kinetics were analyzed under different experimental conditions, and different models were assayed to determine the adsorption mechanism. Dye adsorption in the adsorbent surface could be considered the rate-limiting step. Different adsorption equilibrium models were evaluated to fit the experimental data. This adsorbent allowed us to reach high Langmuir adsorption capacity for both dyes (MB: 341 mg·g−1, MG: 364 mg·g−1 at 25 °C and 0.5 g·L−1). Moreover, kinetic and equilibrium adsorption data have been used to simulate breakthrough curves in a packed-bed column using different conditions (bed length, liquid flowrate, and dye initial concentration). The simulation results showed that almond shell activated carbon is a suitable adsorbent for methylene blue and malachite green removal from wastewater. [ABSTRACT FROM AUTHOR]

The movement of solutes in soil is crucial due to their potential to cause soil and groundwater pollution. In this study, a mathematical model based on the Advection Dispersion Equation (ADE) was developed to evaluate solutions for solute transport. This equation enabled us to attain a relationship for concentrations at different locations and times, also known as the breakthrough curve. Five columns (5 cm in diameter and 30 cm in height) of soil types were prepared to check the validity of the results. An evaluation of the calculated relations showed high accuracy in estimating the breakthrough curve and the saturated hydraulic conductivity of the soil. [ABSTRACT FROM AUTHOR]

Discharging effluents containing dyes into water bodies pose serious environmental problems such as deterioration of water quality. Adsorption is an efficient method to remove dyes from these effluents but has a challenge of high cost of adsorbent. The adsorption of Crystal Violet (CV) dye from aqueous solution onto a low-cost adsorbent, Jatropha tanjorensis leaf powder was investigated using a fixed bed column. The Jatropha tanjorensis leaf powder was prepared and characterised. Breakthrough curves were used to study the performance of the fixed bed column by varying the initial concentration (10-50 mg/L), flowrate (10-20 mL/min) and bed height (5-15cm). The experimental data were analysed using three fixed-bed adsorption column models namely, Thomas, Adams-Bohart and Yoon and Nelson column models and the results fitted well into Thomas and Yoon and Nelson column models with a high correlation coefficient (R² > 0.964) at different conditions. The maximum bed capacity of 334 mg/g related to Yoon and Nelson model was obtained when the column bed height was kept at 15 cm, initial concentration of 30 mg/L and flow rate of 10 mL/min. The activated Jatropha tanjorensis leaf powder was shown to be suitable adsorbent for adsorption of CV dye using fixedbed adsorption column. [ABSTRACT FROM AUTHOR]

The most practical application for wastewater treatment is the removal of dyes from aqueous solutions through fixed-bed column adsorption studies, which are conducted using MWCNT-foam. In this study, Multiwalled carbon nanotube (MWCNT)-foam nanocomposites were fabricated using the low-temperature chemical fusion (LTCF) process. These foam-based composites were subsequently employed in fixed-bed continuous flow column adsorption studies to remove anionic Congo Red (CR) and cationic Methylene Blue (MB) dyes from aqueous solutions. A fixed-bed column, packed with MWCNT-foam (bed height: 0.6 and 1.1 cm), was used to adsorb MB and CR from dye solutions (50 mg L–1). The column exhibited adsorption capacities of 5.6 and 7.8 mg g–1 for MB and CR, respectively, at a flow rate of 2 mL min–1. To assess the impact of bed height, flow rate, and initial dye concentration on column adsorption performance, breakthrough curves were analyzed using multiple models. The Thomas model provided the predicted adsorption capacities for both dyes as 14.46 mg g–1 for MB and 15.49 mg g–1 for CR. The τ values for both dyes were calculated using Yoon–Nelson model as 151 min for MB and 203 min for CR. The Adams–Bohart model predicted the N0 values as 17.33 mg L–1 for MB and 22.96 mg L–1 for CR. Moreover, the adsorption capacity of the MWCNT-foam composite in the fixed-bed column remained relatively stable even after three regeneration cycles, demonstrating its potential for long-term use in dye removal applications. [ABSTRACT FROM AUTHOR]

Inter alia due to the high demand for lithium‐ion batteries, the required critical heavy metals have become a scarce resource. Consequently, effective recycling processes that enable the recovery of such materials are of high interest. A silica adsorbent functionalized with amino‐polycarboxylate derivate ligands (HSU331) was applied in order to selectively adsorb nickel(II) and cobalt(II). Subsequently, suitable parameters for a pH‐swing desorption were investigated. Maximum desorption efficiencies for Co(II) were achieved at pH = 2.7 (72 %) and for Ni(II) at pH = −0.5 (94 %). These results were used for the design of a pH‐shift desorption process in order to selectively recover Co(II) and regenerate the adsorbent after simultaneous adsorption of Co(II) and Ni(II). [ABSTRACT FROM AUTHOR]

As a promising alternative water source to alleviate irrigation water scarcity in red soil regions in southern China, low-quality water could enhance regional water resource utilization and promote sustainable agriculture. However, its soluble salt and ions could affect soil solute distribution and transport, potentially hindering crop growth. Undoubtedly, it is necessary to understand the mechanism of solute transport in red soil under low-quality water irrigation with different water salinity levels. Therefore, a one-dimensional vertical water infiltration experiment and a solute breakthrough experiment were conducted to evaluate the solute transport (soluble salt, Na+, and Cl−) in unsaturated and saturated homogenous red soil at different salinity levels [1 (S1), 2 (S2), 3 (S3), 5 (S5), and 10 (S10) g/L] when irrigated with simulated low-quality water using analytical-grade NaCl. Moreover, the potential factors affecting salt distribution in unsaturated red soil were determined. The findings indicate positive linear relationships between accumulations of three solutes and irrigation water salinity. Generally, the depth of maximum solute concentration increased with the increase in irrigation water salinity. Soluble salt, Na+, and Cl− exhibited early breakthrough and trailing in red soil, but higher irrigation water salinity could reduce PV and retardation. A mobile and immobile water model (MIM) showed that convection was dominant in solute transport in red soil under low-quality water irrigation. D decreased as a power function with increasing irrigation water salinity, while v and R decreased linearly. Furthermore, the red soil can adsorb Cl− resulting from its special charge characteristics under low-quality water irrigation, which may be the main source of salt adsorption. Additionally, v > soil pH > βsalt primarily influenced salt distribution in the 0–40 cm soil profile. This study can provide insights into solute transport in red soil under low-quality water irrigation, facilitating soil fertility and structure, as well as low-quality water irrigation strategy optimization. [ABSTRACT FROM AUTHOR]

At‐a‐station hydraulic geometry (AASHG) relationships describe the dependence of a river's width, mean depth and mean velocity on discharge at a given location, and are typically modelled as power‐law functions. They are often used when modelling stream temperature under unsteady flow conditions. Deriving AASHG relationships is challenging for steep proglacial streams due to the combination of complex morphology and velocity distributions, and rapidly varying flow. The objective of this study was to combine tracer injections with drone‐based photogrammetry to derive AASHG relationships for a steep proglacial channel and to quantify whitewater coverage and its relationship with discharge to support process‐based stream temperature modelling. Velocity–discharge and width–discharge relationships were reasonably well characterised using power‐law functions, but varied amongst sub‐reaches. Whitewater coverage as a fraction of total stream surface area generally exceeded 50% for the range of flows sampled, and exhibited a statistically significant positive relationship with discharge, which varied amongst sub‐reaches. For the range of flows captured during drone flights, the relationship could be represented by a linear function. However, an asymptotic model would be required to extend the relationship to higher flows. The magnitude of whitewater coverage indicates that the albedo of the stream should be substantially higher than values typically used in stream temperature models, and the relationship with discharge means that ongoing glacier retreat, and the associated reduction in summer discharge, should result in lower albedo and higher downstream warming rates, reinforcing the effects of decreasing velocity and mean depth as flows decline. [ABSTRACT FROM AUTHOR]

[Objective] To investigate the effects of different sand blending rates on the hydraulic properties and solute transport processes of moderately saline soils. [Methods] Four sand mixture ratios were established using an indoor soil column test: CK (0 sand mixing), B1 (10% sand mixing), B2 (15% sand mixing), and B3 (20% sand mixing), to investigate the solute transport characteristics of moderately saline soils under different sand mixing conditions and to perform model simulations. [Results] (1) In the range of 0~20%, sand mixing in moderately saline soil will obviously affect the change of soil moisture characteristic curve, and the larger the proportion of sand mixing, the closer the curve is to the Y-axis. Under any suction condition, the soil water content was ranked as CK>B1>B2>B3, and the larger the proportion of sand mixing, the more small pores in the soil, the reduction of small pores, and the weakening of soil water-holding properties. The saturated hydraulic conductivity of the soil increased with the increase of sand doping. (2) With the increase of sand doping, the solute penetration curve shifted significantly to the left, and the initial penetration time, complete penetration time, and total penetration time were reduced, and the total penetration time of B1, B2, and B3 treatments were reduced by 34.48%, 47.22%, and 69.71%, respectively, compared with that of CK. (3) Both the CED equation and the two-zone model can simulate the solute transport in soil under sand doping conditions well, but the fitting accuracy of the two-zone model is higher compared with the CDE equation. Analyses of the fitted parameters of the two-zone model showed that the soil pore flow rate, the water content ratio of the movable zone and the mass exchange coefficient gradually increased with the increase of sand doping, while the hydrodynamic dispersion coefficient and the dispersion degree showed a decreasing trend. [Conclusion] Therefore, sand blending in saline soils can effectively improve soil hydraulic properties, promote solute transport in the soil, and help alleviate the adverse effects of salinity on crop growth. The results of this study can provide reference for saline soil improvement and management work, and provide theoretical support and practical guidance for future research and practice.

The selection of appropriate transport parameters of radionuclides is of utmost importance in the safety assessment of radioactive waste disposal sites. Both batch and column methods are widely performed to determine the transport parameters of radionuclides through soil layers. In this paper, the distribution coefficients Kd of Co ions in sandy mixtures containing soil samples taken from Anarak near-surface repository (Iran) were determined by batch and 3 different column methods namely, breakthrough curve, thin-section, and gamma spectroscopy methods. The distribution coefficients Kd of the mixture was obtained as 160 L kg−1 for the batch method, 23 L kg−1, 19 L kg−1, and 18 L kg−1 for the breakthrough curve, the thin-section, and the gamma spectroscopy methods, respectively. These results emphasize proper selection of transport data for using in the safety assessment programs.

Abstract Bottlenecks inherent in batch and column adsorption configurations have impeded the implementation of the adsorption technique in large-scale wastewater treatment systems. This study mainly aimed to develop an innovative wastewater treatment prototype that integrates inclined plate settlers (IPS) and composite adsorbent coating (CAC). The objective is to enable the removal of Cd2+ from aqueous solutions in a continuous setup, thereby enhancing its practicality for large-scale applications. The combined IPS-CAC system was optimized at various angle of inclination (θ), influent flow rate (Q) and adsorbate initial concentration (C o) using the Box–Behnken Design (BBD) of the Response Surface Methodology (RSM). At optimized operating parameters (θ = 45°, Q = 5 ml/min and C i = 1.87 mg/L) the IPS-CAC Cd2+ predicted (R 2 = 0.9926) and experimental removal efficiencies were 75.8% and 69.7 ± 4.67%, respectively. The IPS-CAC breakthrough adsorption capacity was 9.6 mg/g. Comparing IPS-CAC performance with a tank without plates and IPS with plain plates, the Cd2+ removal efficiencies were 2.4 ± 0.1% and 4.6 ± 1.1%, respectively, confirming the synergistic effect of IPS and CAC. Additionally, breakthrough curves were acquired for various flow rates, cadmium influent concentrations, and plate inclination angles. Only a 10% decline in the removal effectiveness (from 69.7 to 59.7%) of the CAC after three adsorption–regeneration cycles was observed, indicating its stability for heavy metal removal. The results underpin the potential of using IPS-CAC for industrial wastewater treatment and enhancing the use of adsorption on a larger scale.

Bottlenecks inherent in batch and column adsorption configurations have impeded the implementation of the adsorption technique in large-scale wastewater treatment systems. This study mainly aimed to develop an innovative wastewater treatment prototype that integrates inclined plate settlers (IPS) and composite adsorbent coating (CAC). The objective is to enable the removal of Cd2+ from aqueous solutions in a continuous setup, thereby enhancing its practicality for large-scale applications. The combined IPS-CAC system was optimized at various angle of inclination (θ), influent flow rate (Q) and adsorbate initial concentration (Co) using the Box–Behnken Design (BBD) of the Response Surface Methodology (RSM). At optimized operating parameters (θ = 45°, Q = 5 ml/min and Ci = 1.87 mg/L) the IPS-CAC Cd2+ predicted (R2 = 0.9926) and experimental removal efficiencies were 75.8% and 69.7 ± 4.67%, respectively. The IPS-CAC breakthrough adsorption capacity was 9.6 mg/g. Comparing IPS-CAC performance with a tank without plates and IPS with plain plates, the Cd2+ removal efficiencies were 2.4 ± 0.1% and 4.6 ± 1.1%, respectively, confirming the synergistic effect of IPS and CAC. Additionally, breakthrough curves were acquired for various flow rates, cadmium influent concentrations, and plate inclination angles. Only a 10% decline in the removal effectiveness (from 69.7 to 59.7%) of the CAC after three adsorption–regeneration cycles was observed, indicating its stability for heavy metal removal. The results underpin the potential of using IPS-CAC for industrial wastewater treatment and enhancing the use of adsorption on a larger scale. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Soil & Water Conservation (1009-2242) is the property of Institute of Soil & Water Conservation and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In porous water filters, the transport and entrapment of contaminants can be modeled as a classic mass transport problem, which employs the conventional convection–dispersion equation to predict the transport of species existing in trace amounts. Using the volume-averaging method (VAM), the upscaling has revealed two possible macroscopic equations for predicting contaminant concentrations in the filters. The first equation is the classical convection–dispersion equation, which incorporates a total dispersion tensor. The second equation involves an additional transport coefficient, identified as the adsorption-induced vector. In this study, the aforementioned equations were solved in 1D for column tests using 3D unit cells. The simulated breakthrough curves (BTCs), using the proposed micro–macro-coupling-based VAM model, are compared with the direct numerical simulation (DNS) results based on BCC-type unit cells arranged one-after-another in a daisy chain manner, as well as with three previously reported experimental works, in which the functionalized zeolite and zero-valent iron fillings were used as an adsorbent to remove phosphorous and arsenic from water, respectively. The disagreement of VAM BTC predictions with DNS and experimental results reveals the need for an alternative closure formulation in VAM. Detailed investigations reveal time constraint violations in all the three cases, suggesting this as the main cause of VAM's failure. [ABSTRACT FROM AUTHOR]

Lack of knowledge on phosphorus transport and retention in soils amended with polyaluminium chloride and anionic polyacrylamide water treatment residuals (PAC-APAM WTRs) makes it challenging to effectively utilize these materials as amendments in traditional soil-based media for stormwater bioretention systems to mitigate phosphorus pollution. This study investigated the impact of initial phosphorus concentration (C0), pH, and flow rate on phosphorus transport and retention in columns of three soil types amended with PAC-APAM WTRs under saturated hydraulic conditions. Results demonstrate that increasing C0 led to a decrease in the retardation factor (Rf) from 30.05 to 26.87, 12.64 to 9.10, and 12.27 to 6.68 in Soil 1 and PAC-APAM WTRs columns, Soil 2 and PAC-APAM WTRs columns, and Soil 3 and PAC-APAM WTRs columns, respectively. Similarly, increasing flow rate resulted in a decrease in Rf from 22.81 to 9.01, 11.14 to 4.74, and 16.13 to 7.57 in the respective columns. The adsorbed phosphorus mass per gram of media increased from 6.4 to 7.2 in Soil 1 and PAC-APAM WTRs columns and 7.6 to 9.8 in Soil 2 and PAC-APAM WTRs columns with increasing C0, but decreased from 16.3 to 8.0, 11.0 to 5.3, and 8.7 to 4.8 in the respective columns with increasing flow rate. No obvious trend was observed regarding the impact of pH on Rf and the adsorbed phosphorus mass. Future research should aim to elucidate the underlying mechanisms governing the comprehensive effects of C0, pH, and flow rate on phosphorus transport under field conditions. [ABSTRACT FROM AUTHOR]

Copyright of Inorganic Chemicals Industry is the property of Editorial Office of Inorganic Chemicals Industry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigated the catalytic chemisorption of cyanogen chloride(CK) with a metal(ASZM) – triethylenediamine(TEDA) complex. XPS data, IR spectra, and DFT calculations demonstrated that the synergetic catalytic hydrolysis of CK by ASZM-TEDA is kinetically favorable, with the enhanced reactivity of water on the catalyst as the primary cause for the accelerated catalytic hydrolysis. To validate the results, ASZM-TEDA was impregnated into activated carbon beads to form a packed-bed reactor for this breakthrough experiment. The proposed species-transport equation parameters were fitted using the genetic algorithm, and the correlation between parameters was compared. The study concludes that TEDA can affect the diffusivity for overall mass transfer-related reactions and accelerate the catalytic reaction of metal with CK. This study is the first to describe chemisorbed breakthrough with catalyst reaction in-depth and provides insights into the optimized ratio between TEDA and metal complexes. This methodology can be applied to various breakthrough experiments with chemical reactions.

Dye pollutants, mainly discharged from the textile industry, have caused severe risks to human health and the ecosystem because of their toxicity, non-biodegradability, and carcinogenicity. This study investigated the use of commercial biochar derived from melaleuca wood as an adsorbent for the removal of methylene blue (MB) using a packed-bed column. The selected biochar was characterized by nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy, and scanning electron microscopy. The experiments were performed to determine breakthrough curves (BTCs) with varying pH (3–9), inflow rate (5–20 mL min–1), bed height (16–65 cm), and initial MB concentration (0.75–9 mg L–1). The biochar (particle size of 1–2 mm) exhibited a low adsorption capacity for MB (~21 mg kg–1), resulting in a short breakthrough time. The Thomas, Bohart-Adams, Yoon-Nelson, and Bed Depth Service Time models were quite suitable for describing the experimental BTCs, with R2-values ranging from 0.92 to 0.98. The obtained BTCs were not in the typical S-shape, which characterizes diffusion-controlled adsorption. Therefore, a serial logistic-exponential model, which accounts for both the mass transfer and interaction contributions, was proposed. The experimental data effectively fit this proposed model, as indicated by high R2-values (>0.998). The dominant influence of mass transfer compared to interaction in controlling the adsorption rate of MB was highlighted.

Heavy metals are pollutants that are generated by different activities, one of which is the dumping of wastewater by industries into bodies of water, which represents a great threat to aquatic and terrestrial biota, as well as health. These contaminants are persistent, bioaccumulative and non-biodegradable, generating a negative effect on the food chain in the area of influence. Nickel is a heavy metal that is used in different types of industries such as battery production. This generates different harmful effects on the human body, such as the cardiovascular or digestive system when exposed in large quantities. The objective of the present study is to use Computer Aided Process Engineering (CAPE) to model an operational column on an industrial scale aimed at the adsorption of Nickel (II) in aqueous solution taking advantage of the biomass of Theobroma cacao L. Consequently, Aspen Adsorption software was used to carry out multiple simulations of an adsorption column using various industrial configurations, with the aim of performing a parametric sensitivity analysis. In the results obtained, it is evident that the Langmuir model - global linear resistance kinetic model (LDF) used to simulate the adsorption column in the elimination of Nickel (II) achieves efficiencies of up to 95.8%. The best conditions for the simulation in the adsorption column were an inlet flow rate of 300 m3/day, a bed height of 5 m and an initial concentration of 2000 mg/L. Furthermore, it was observed that increasing the inlet flow led to a decrease in the rupture and saturation time of the process, while increasing the bed height presented an increase in the rupture and saturation time. On the other hand, concentration did not significantly affect the efficiency of the process. [ABSTRACT FROM AUTHOR]

Rivers, as water resources, are considered an origin of supply for many requirements of urban communities. River networks consist of many branches that connect at river confluences. Because pollutants usually enter the river in different situations from the upstream branches of river intersections, it is essential to investigate the mixing process through the river network. For this purpose, precise analytical and numerical models should be used to evaluate this phenomenon quantitatively. Based on the cell concept and separation of advection and dispersion operations, this study developed a new analytical relationship through the confluences of rivers. A physical model of the Y-shaped junction was created in the laboratory, and four inlet flow discharges 25, 21, 12, and 9 l/s and three initial concentrations of sodium chloride solution 80, 160, and 200 g/L were selected as study parameters. Then, the concentration-time curves along the sub-branches, the intersection, and the downstream of the river's main channel were taken at 2-second intervals. In order to evaluate the efficiency of the analytical model, the parameters of the model were first calculated by coding based on its framework and using the least squares method. Then the analytical curves were outlined versus the experimental results. It was observed that the presented model could produce double-peaked curves and also cover experimental data series precisely. The dispersion coefficients and the related time parameter in the presented model (T) were found to increase by moving downstream of the river junction. It was also observed that the Peclet numbers (Pe = xu/D ) are increased like dispersion coefficients by increasing the distance downstream of the confluence. In addition, the research results showed that increasing the residence time parameter in dispersion cells (T) causes growth in the dispersion coefficient, despite increasing the residence time in advection cells (β), compelling the movement of the pollutant breakthrough curves. [ABSTRACT FROM AUTHOR]

Underground coal gasification (UCG) is a promising technology, but the groundwater pollution caused by UCG is a potential risk to the environment. The measured results of the stratum in the combustion cavity resulting from UCG had proven that the combustion cavity would be filled with some UCG residues and caving rocks when UCG was finished. The pollutants in underground water around the combustion cavity include organic pollutants, inorganic pollutants, and ammonia nitrogen, and one of the primary organic pollutants is phenol. The migration and diffusion characteristics of organic pollutants (taking phenol as a representative) in the groundwater of the combustion cavity were investigated by breakthrough experiments and numerical simulations. The results show that the hydraulic conductivity of the coarse UCG residues is much higher than that of fine residues, and the hydraulic conductivity of the UCG residues with the size of − 0.15 mm and 0.15–0.3 mm are 4.68 × 10−6 m/s and 1.91 × 10−4 m/s respectively. The dispersivity λ for the migration of organic pollutants will be influenced significantly by the size of UCG residues in fractures of the combustion cavity, while the distribution coefficient Kd will not. The dispersivity of organic pollutants in the fine UCG residues is more significant than that in the coarse residues, and the λ for the two kinds of residues are 3.868 cm and 1.765 cm, respectively. The shape of the migration path slightly affects the pollutant concentration distribution along the path, but the width of a path has a more pronounced influence on the concentration distribution. In this research, the influence was formulated by a new technical term, MPWIT, which is related to transverse dispersion. Specifically, while the transverse dispersion values account for 20% and 10% of the longitudinal dispersion, respectively, the corresponding MPWIT values are 39.48 mm and 33.96 mm. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Petrochemical Universities / Shiyou Huagong Gaodeng Xuexiao Xuebao is the property of Journal Editorial Department Of Liaoning Shihua University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Ecology & Rural Environment is the property of Journal of Ecology & Rural Environment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

River networks consist of many branches that connect at river confluences. Because pollutants usually enter the river in different situations from the upstream branches, it is essential to investigate the mixing process through the river network. Based on the cell concept and separation of advection and dispersion operations, this study developed a new analytical relationship through the confluences of rivers. A physical model of the Y-shaped junction was created in the laboratory, and four inlet flow discharges 25, 21, 12, and 9 l/s and three initial concentrations of sodium chloride solution 80, 160, and 200 g/L were selected as study parameters. Then, the concentration-time curves along the sub-branches, the intersection, and the downstream of the river's main channel were taken at 2-second intervals. In order to evaluate the efficiency of the analytical model, the parameters of the model were first calculated by coding based on its framework and using the least squares method. It was observed that the presented model could produce double-peaked curves and also cover experimental data series precisely. The dispersion coefficients and the related time parameter in the presented model (T) were found to increase by moving downstream of the river junction. It was also observed that the Peclet numbers 〖(P〗_e=xu/D) are increased like dispersion coefficients by increasing the distance downstream of the confluence. In addition, the research results showed that increasing the residence time parameter in dispersion cells (T) causes growth in the dispersion coefficient, despite increasing the residence time in advection cells (β).

Adsorbents based on agricultural biomass have been subjected to several investigations in recent years owing to their low cost and promising adsorption capabilities. This paper aimed to demonstrate the efficiency of date pits activated with phosphoric acid as common activating agent that increases the porosity and surface area of date pits. This results in a greater number of binding sites for the heavy metals to attach to improving the bio-adsorbent's effectiveness. To get rid of heavy metals such as zinc and copper ions from industrial wastewater using a fixed bed with a continuous flow configuration, the derived adsorbent was tested under a variety of operating conditions, including a flow rate of 4-12mL/min, an initial metal ion concentration of 30-60mg/L, and temperatures ranging from 20 to 50°C, which were chosen based on industrial conditions and available data. The results revealed that the removal efficiency of heavy metals increased with an increase in the initial metal ion concentration, but conversely, it decreased with an increase in flow rate and temperature. Also, the results indicated that with the optimum conditions of 15cm static bed height, 60mg/L initial metal concentration, 8mL/min flow rate, and 25°C temperature, determining the ideal conditions results in the efficient removal of pollutants in less time and the treatment of larger quantities. Mathematical modeling of the fixed bed column was achieved using the kinetic models of Adams Thomas, Yoon-Nelson, Bohar, and Modified Dose-Response, in this regard, the Thomas model is the closest to the experimental values, it is supposed that the adsorption mechanism was a Langmuir type adsorption followed by a pseudo-second-order chemical sorption. The Yoon-Nelson approach was employed on experimental data to predict breakthrough curves through nonlinear regression. This made it easier to determine the crucial characteristic column parameters for process design. According to thermodynamic studies, heavy metals spontaneously and exothermally adsorb activated carbon in date pits. Firstly, spontaneous adsorption indicates efficient processes that occur favorably without external energy input, offering cost-effective solutions for various applications. Secondly, the exothermic nature of adsorption suggests that lower temperatures may be sufficient, reducing energy consumption and preserving the stability of sensitive materials. Additionally, the process's exothermicity facilitates desorption at higher temperatures, enhancing the efficiency of regeneration processes. This study has shown that BDP can successfully remove heavy metals from aqueous solutions. Understanding these characteristics is crucial for optimizing applications, reducing costs, and improving overall efficiency in industrial and environmental contexts. [ABSTRACT FROM AUTHOR]

In this work, lead(II) adsorption on activated carbons, tire-derived activated carbon (TAC), and commercial activated carbon (CAC), in a packed-bed column, was simulated using the Aspen Adsorption® V11 flowsheet simulator. The simulator was used to model the fixed-bed adsorption column and to establish the breakthrough curves by varying the initial concentration of lead(II) ions (500 mg/L, 1000 mg/L, 2000 mg/L, and 3000 mg/L), the bed height (0.2 m, 0.3 m, 0.4 m, 0.5 m, and 0.6 m), and the flow rate (9.88 × 10−4 m3/s, 1.98 × 10−3 m3/s, 2.96 × 10−3 m3/s, 3.95 × 10−3 m3/s, and 4.94 × 10−3 m3/s), at constant temperature and pressure of 25 °C and 3 bar, respectively. At the optimum conditions of 500 mg/L lead(II) concentration, 0.6 m bed height, and 9.88 × 10−4 m3/s flow rate, the breakthrough times were 488 s and 23 s for TAC and CAC, respectively. Under the same conditions, the adsorption capacity obtained at t0.5 was 114.26 mg/g for TAC and 7.72 mg/g for CAC. The simulation results indicate the potential of TAC for the adsorption of lead(II) in comparison to CAC. [ABSTRACT FROM AUTHOR]

Dye pollutants, mainly discharged from the textile industry, have caused severe risks to human health and the ecosystem because of their toxicity, non-biodegradability, and carcinogenicity. This study investigated the use of commercial biochar derived from melaleuca wood as an adsorbent for the removal of methylene blue (MB) using a packed-bed column. The selected biochar was characterized by nitrogen adsorption-desorption isotherms, Fourier transform infrared spectroscopy, and scanning electron microscopy. The experiments were performed to determine breakthrough curves (BTCs) with varying pH (3-9), inflow rate (5-20 mL min-1), bed height (16-65 cm), and initial MB concentration (0.75-9 mg L-1). The biochar (particle size of 1-2 mm) exhibited a low adsorption capacity for MB (~21 mg kg-1), resulting in a short breakthrough time. The Thomas, Bohart-Adams, Yoon-Nelson, and Bed Depth Service Time models were quite suitable for describing the experimental BTCs, with R2-values ranging from 0.92 to 0.98. The obtained BTCs were not in the typical S-shape, which characterizes diffusion-controlled adsorption. Therefore, a serial logistic-exponential model, which accounts for both the mass transfer and interaction contributions, was proposed. The experimental data effectively fit this proposed model, as indicated by high R2-values (>0.998). The dominant influence of mass transfer compared to interaction in controlling the adsorption rate of MB was highlighted. [ABSTRACT FROM AUTHOR]

In karstic environments, it is not unusual for an underground river to split into two or more streams (diffluence) and merge back together downstream (confluence). This kind of behavior can generate multipeaked breakthrough curves (BTCs) in dye tracing at a sampling site located downstream of the confluence(s). It is also possible that such a phenomenon is difficult to highlight with dye tracing if the tracer clouds coming from the different streams reach the sampling locations at the same time. In this study, an attempt at quantifying the importance of different criteria in the occurrence of a multipeaked BTC is done by performing a dye tracing campaign in a two-tributaries diffluence-confluence (DC) system and using a one-dimensional solute transport model. The results from both field data and the solute transport model suggest that a double-peaked BTC occurs downstream of a DC system if the following conditions are met: (1) the injection is done close enough to the diffluence, (2) the sampling point is located not too far from the confluence, and (3) the two (or more) streams have sufficiently contrasted travel times from the diffluence to the confluence. The paper illustrates that, even if a diffluence occurs in a karstic river, multipeaked BTCs are not necessarily observed downstream of the confluence if these three conditions are not met. Therefore, characterizing a DC system using dye tracing is a real challenge. This could explain why publications that report studies involving multipeaked BTCs are quite rare. [ABSTRACT FROM AUTHOR]

Explicit fracture models often use analytical solutions for predicting flow in fractured media, usually assuming uniform fluid viscosity for simplicity. This assumption, however, can be inaccurate as fluid viscosity varies due to factors like composition, temperature, and dissolved substances. Our study, recognizing these discrepancies, abandons this uniform viscosity assumption for a more realistic model of variable viscosity flow, focusing on viscous displacement scenarios. This includes instances like injecting viscous surfactants for hydrocarbon recovery in fractured reservoirs or soil decontamination. This presents a significant challenge, enhancing our understanding of transport within fractures, mainly governed by advection. Our study centers on a low‐permeability rock matrix intersected by two fractures with variable apertures. We employ two methods: an analytical approach with a new solution and numerical simulations with two distinct in‐house codes, discretizing both the rock matrix and fractures with two‐dimensional triangular elements. The first code uses a Discontinuous Galerkin finite element method, while the second utilizes a finite‐volume method, allowing a comprehensive comparison of solutions. Additionally, we investigate parameter identifiability, like fracture apertures and viscosity ratios, using breakthrough curves from our analytical solution, applying the Markov Chain Monte Carlo technique. Key Points: Analytical model developed for variable viscosity flow in fractured media, overcoming the common uniform viscosity assumptionAnalytical and numerical solutions demonstrate overall consistency, with minor discrepancies observedBreakthrough curves from the analytical solution, using Markov Chain Monte Carlo, enable confident estimation of fracture apertures [ABSTRACT FROM AUTHOR]

Adsorption using solid adsorbents is a promising technique for capturing carbon dioxide (CO2) to reduce greenhouse gas emission. In the present work, palm shell-based activated carbon was functionalized with eco-friendly activating agents including potassium carbonate, potassium acetate, binary deep eutectic solvent (DES) composed of choline chloride and ethylene glycol, and ternary DES composed of choline chloride, urea and ethylene glycol by impregnation method. Post-combustion CO2 adsorption performance of the functionalized adsorbents was evaluated in a fixed-bed adsorption column under varying adsorption temperature (25-55°C) and inlet CO2 concentration (15-20%), followed by a cyclic CO2 adsorption study to determine the regeneration ability of the adsorbents. The results revealed that activated carbon modified with potassium acetate (ACPA) exhibited remarkably high CO2 adsorption capacity of 116.5 mg/g and breakthrough time of 54 min at 25°C and 15% inlet CO2 concentration. Furthermore, ACPA demonstrated good regeneration ability even after seven adsorption-desorption cycles. Interestingly, it was found that activated carbon modified with ternary DES (AC-DES 4) exhibited significantly higher adsorption capacity than activated carbon modified with binary DES (AC-DES 2). It is worth mentioning that the present work is the first study that uses ternary DES as activating agent for such purpose. [ABSTRACT FROM AUTHOR]

Accurate isotherm models contribute to predicting the amount of adsorbate adsorbed in the adsorbent within a certain range of pressure and temperature. Experimental adsorption isotherms of five components (CO 2 , CO, N 2 , CH 4 and H 2) on pelletized zeolite 13X from publication data were correlated with common-used fundamental isotherm models, including Langmuir, Sips, dual-site Langmuir (DSL), and temperature-dependent (TD) isotherm models, including TD Langmuir, TD Sips and TD DSL. Overall, the average relative errors (AREs) of TD models are higher than those of common-used fundamental isotherm models, but TD models have better applicability. In addition, three surrogate artificial neural networks (ANNs) optimized by genetic algorithm (GA) of single- and multi-component gas adsorption isotherm models are proposed. Three GA-ANN models set the adsorption amount as the output and take one, two or three potential inputs, such as adsorption pressure, temperature and adsorbate components. Three GA-ANN models generally have lower AREs and better applicability than fundamental isotherm models and TD isotherm models. The proposed GA-ANN3 model, which has three inputs, makes a new attempt at adsorption isotherms and can fit the multi-component gas adsorption at different temperatures with the change of adsorption pressure. The adsorber dynamics for multi-component adsorption (CO 2 : CO: N 2 : H 2 = 19.9: 0.1: 44.6: 35.4 mol%) in zeolite 13X bed are compared by the extended TD Langmuir model and extended TD DSL model. Since the AREs of the TD DSL model are smaller than that of the TD Langmuir, the breakthrough curves of multi-component gas simulated by the TD DSL model are better than that of TD Langmuir. These results can contribute to relevant researchers choosing suitable adsorption isotherm models for numerical simulations of adsorption processes. • Fitted dual-site Langmuir model performs better in breakthrough curve simulation. • Artificial neural network (ANN) enables construction of adsorption isotherm models. • Genetic algorithm (GA) optimizes the weights and biases of ANN for better performance. • Three GA-ANN models have lower average relative errors and better applicability. • GA-ANN3 attempts to express adsorption isotherms for multi-component mixtures. [ABSTRACT FROM AUTHOR]

Abundant, easily accessible, and low-cost agro-industrial residues represent attractive alternatives for removing emerging contaminants from water. In this work, the aqueous adsorption of caffeine/triclosan onto rice husk (RH) was studied in batch and continuous processes. For this purpose, adsorbents with three particle size ranges (120–150, 300–600, 800–2000 µm) were prepared and evaluated. The composition, structure, surface morphology, functionality, and specific surface area of the RH biosorbents were determined. This characterization revealed that RH primarily consists of lignin, cellulose, and hemicellulose, making up to 80.1% of its composition. RH also exhibited an irregular surface, with several functional groups (OH, C=O, CH, C=C, C-OH), and a relatively small specific surface area (1.18 m2/g). Batch tests were carried out using different RH sizes, doses (1–50 g/L), and contact times (5–300 min), using 20 mL of caffeine/triclosan solutions (30 mg/L). Tests were conducted to fit the most adequate kinetics and isotherm models. The optimal doses (g/L) for caffeine and triclosan removal were 4.5 and 1.5 with small RH, 8.5 and 2.5 with medium RH, and 50.0 and 10.0 with large RH, respectively. The optimal contact times for all three particle sizes were 180 and 60 min. Triclosan removal was greater than that of caffeine (2.5–25.5%) with all three particle sizes, requiring less adsorbent (2.5–5.0 times) and shorter times (3 times). The experimental data fit better the Sips isotherm and Elovich kinetics models. The small (120–150 µm) particles achieved the highest caffeine/triclosan batch adsorption capacities (6.3/28.6 mg/g). Continuous tests were performed on fixed-bed columns of 1 cm in diameter, packed with 4, 5, and 8 cm of RH, operated with hydraulic loading rates between 2 and 4 m3/m2day. Small particles also reached the highest adsorption capacity in the removal of caffeine (352.7 mg/L) and triclosan (3797.2 mg/L), and the experimental data were well-fitted to the Bohart–Adams model. The research results not only demonstrate the effective removal of contaminants but also illustrate the versatility and applicability of rice husk in various conditions and systems. [ABSTRACT FROM AUTHOR]

In the present paper, a Cu(BDC) metal–organic framework (MOF) is chemically attached to wool via an in-situ synthesizing method. The synthesized novel biocomposite (Cu(BDC)@Wool) was applied as an easily applicable biocomposite to the effective removal of Rifampicin (RIF) from wastewater. Batch adsorption experiments were performed, and the optimum conditions of RIF adsorption (99.3%) were found to be approximately at 25 ppm initial concentration, 1 mg adsorbent, pH 2, time without ultrasonic = 30 min, and time with ultrasonic = 10 which were determined by a response surface methodology. The results of fixed bed experiments showed that better RIF removal was achieved with a low inlet RIF concentration, high adsorbent bed height, and low influent flow rate. The performance of FBAC was maximum (tb = 769, te = 1221 min; %A = 60.6%) at a flow rate of 0.5 mL/min, adsorbent bed height of 7.5 mm, and RIF of 30 ppm. The study of mathematical models shows that the Clark model has the highest correlation with the experimental data. Therefore, the novelty of this work is that ultrasound-assisted removal reduces the equilibration time and can be economically viable for removing RIF from wastewater. [ABSTRACT FROM AUTHOR]

Most traditional D2/H2 separation techniques are energy‐intensive with low efficiency. Metal–organic frameworks (MOFs) provide a promising solution for D2/H2 separation due to their excellent chemical and structural characteristics. Here, machine learning‐assisted high‐throughput computational screening was employed to identify the high‐performance MOFs for the dynamic D2/H2 separation. Extensive data analysis reveals that there were two adsorption behaviors in the optimal MOFs, independent adsorption and competitive adsorption, and the independent adsorption was favorable for the preferential adsorption of D2. To quantify these two adsorption behaviors, we introduced and defined overlap degree (OD) and independence degree (ID), and developed a software for the rapid assessment of OD/ID. After batch simulation of the breakthrough curves of 2000 optimal MOFs, ~80% MOFs exhibited independent occupancy, confirming its contribution to good dynamic separation capabilities. This work provides a new idea for designing MOFs with independent adsorption behavior to improve the dynamic separation performance of hydrogen isotopes. [ABSTRACT FROM AUTHOR]

AbstractThe biomass obtained from the stem of Gum Arabic tree was used to prepare a thermally activated carbon through pyrolysis at 800 °C. The activated carbon tagged GAAC-800 was used as adsorbent for the fluoride sequestration in a batch and a fixed-bed reactor in a continuous column systems. The surface morphology, elemental composition as well as particle size distribution of the adsorbent was investigated with Scanning Electron Microscopy (SEM), Elemental and Particle Size Analyzers. Also, the influence of initial fluoride concentrations, column packing height and the flow rate on the column efficiency were examine while the efficiency of batch process as a function of contact time and temperature was also investigated. It was found that the kinetic of the process was best fitted with second order model, while the mechanism was best explained by interparticle diffusion model. In addition, the Langmuir Isotherm model showed that the maximum monolayer adsorption capacity of fluoride removal was 71.93 mg/g. The breakthrough curve from the fixed bed adsorption data were well modeled by Adams-Bohart, Yoon-Nelson and Clark model. The models were judged using Akaike Information Criteria (AIC) values after statistical evaluation. GAAC-800 removed fluoride from aqueous solution comparably higher than other adsorbent in its category in batch and continuous column systems. [ABSTRACT FROM AUTHOR]

The adsorption of Congo red (CR) dye from aqueous solutions is conducted in a continuous fixed-bed column by using agricultural biomass of Nelumbo nucifera leaf adsorbent. The column performance is evaluated by varying the adsorbent bed height (2.5‒5 cm), influent dye concentrations (10–50 mg L−1), and inlet flow rate (1‒5 mL min−1). Column experimental data confirmed that the breakthrough characteristics of the adsorption system are dependent on bed height, flow rate, and initial adsorbate concentration. The results show that the decolourisation efficiency and equilibrium uptake (qe) of CR decreases with increasing flow rate and increases with increasing bed height and influent adsorbate concentration. The maximum absorption efficiency (83.12%) was obtained using 5 cm bed height, 15 mg L−1 inlet adsorbate concentration, and 1 mL min−1 flow rate. The increased flow rate and initial adsorbate concentration lead to a shorter column exhaustion time. The length of mass transfer zone increased with increasing bed height. Various mathematical models are applied to column experimental data to predict the breakthrough curve and to evaluate the column capacity and kinetic constants of the models. The correlation between the experimental and theoretical data is quantified by calculating the regression coefficients for the Thomas and Yoon–Nelson models, an R2 ≥ 0.954 at various operating conditions was obtained, which shows that the trend of experimental data fits well and the overall system kinetics are limited by solid-liquid interphase mass transfer. The N. nucifera leaf fine powder adsorbent is proven to be capable of removing CR efficiently from aqueous solutions in continuous fixed-bed systems at low flow rate and higher bed depth and it can be used effectively in wastewater treatment. [ABSTRACT FROM AUTHOR]

This study explored diethanolammonium chloride ([DEA]Cl) as a potential ionic liquid from low‐cost and commercial ones for gas separation. There are three kinds of functional sites in [DEA]Cl: acidic NH2+, hydrogen‐bond OH, and nucleophilic Cl−. The separation of NH3/N2/H2, SO2/CO2/N2, and H2S/CO2/CH4 was considered, because the three mixtures are extensively involved in many industrial processes. The experimental results demonstrated that [DEA]Cl exhibited excellent ability to separate the mixture of NH3/N2/H2. The [DEA]Cl also exhibited the proper capacity to separate SO2/CO2/N2, but the capacity of [DEA]Cl for the separation of H2S/CO2/CH4 was inferior. The theoretical calculations revealed that NH2+ and OH worked synergistically to contribute to the ability of [DEA]Cl for excellent separation of NH3 from NH3/N2/H2, with Cl− contributing to the proper separation of SO2 from SO2/CO2/N2. This study provides experimental and theoretical basis for the industrial application of [DEA]Cl in the area of gas separation. [ABSTRACT FROM AUTHOR]