Transfer Zone Research Articles

Numerical modeling of the transfer length of 17.8 mm (0.7 in) diameter prestressing strands in pretensioned members

The bond between concrete and reinforcing steel bars in reinforced concrete structures is crucial. Prestressing strands with a diameter of 17.8 mm (0.7 in) transfer higher compression per unit area than smaller strands, improving moment capacity and shear strength and extending the girder span. However, limited research on the bond performance of these 17.8 mm diameter prestressing strands has restricted their widespread use despite their advantages. This study presents a methodology to determine the transfer length of pretensioned members numerically. The influence of pretension force and bond strength on a 17.8 mm diameter strand was assessed through the validation of a finite element model using experimental results from a standardized pretensioned pull-out test. Analytical calculations using different code formulas were also conducted, encompassing strands of varying diameters. Our finite element analysis suggests that a 50.8 mm spacing between adjacent 17.8 mm diameter strands is applicable, ensuring there is no stress overlap in the transfer zones, which can lead to concrete cracking and reduced structural integrity. Existing code formulas, such as ACI 318–19 and AASHTO LRFD 9th edition, require longer transfer lengths when compared with the numerical results. The fib MC 2010 and EC2 formulas offer closer results to numerical results of smaller diameter strands but underestimate the transfer length for the 17.8 mm diameter strand. Therefore, improvements to code formulations may be necessary for more accurate transfer length predictions for this specific strand size.

Deciphering the complex history of the cabo frio high – SE brazilian continental margin

Extensive seismic reflection interpretation of the Cabo Frio High allowed better understanding of its proximal and distal structure. Seismic lines helped map the salt base and recognize the primary geological interfaces, unconformities, faults, and volcanic intrusions. The proximal Cabo Frio High is a continental basement uplift extending mainly into the Campos Basin. The Cabo Frio Outer High, which is of volcanic origin, lies between Santos and Campos Basins. This volcanism is concentrated at the crossing of two significant structures: Cruzeiro do Sul Lineament and Rio de Janeiro Fracture Zone. The Cabo Frio High fits an NW-SE fold axis, which is well correlated with distension along NW-SE direction generating a regional E-W sinistral plate movement, mainly related to the ENE-WNW sinistral Rio de Janeiro transfer zones. The accumulated uplift is approximately 4 km, achieved by at least four uplifting pulses. The uplifting starts in the Albian-Santonian, characterized by the elevation of the northeast portion of Cabo Frio High, followed by erosion. The sill and dikes intruded in the Upper Cretaceous, and the uplift of the southwest portion of the Cabo Frio High characterizes the second uplift pulse. Subaerial Eocene volcanos characterize the third uplifting pulse. The uplifting of the Blue Marker horizon (Oligocene) characterizes the last pulse.

Analytical model for RC beams with embedded prestressed Fe-SMAs

Prestressed iron-based shape memory alloy (Fe-SMA) strengthening is an effective means to enhance the performance of reinforced concrete (RC) structures. The applied prestress level significantly influences the strengthening efficiency. However, the absence of a reliable model predicting the applied prestress hinders the efficient design of prestressed Fe-SMA strengthening solutions. To fill this gap, the current study proposes an analytical model, with which a constant zone and a transfer zone are identified in strengthened RC beams. The constant zone, with zero interfacial shear stress, sustains a constant prestress level, while the transfer zone, experiencing non-zero shear stress, gradually reduces the Fe-SMA tensile stress from the prestress level to zero. Validated through experiments, the proposed model accurately predicts the applied prestress levels and prestress-induced deflections in RC beams strengthened with Fe-SMAs and more conventional carbon fiber reinforced polymers (CFRPs). Further analysis reveals that the transfer zone length ranges from 4 to 7 characteristic lengths, and it is proportional to the logarithm of the applied prestress level. Simplifying a constant prestress level within the beam span yields sufficiently accurate prestress analysis.

Development of arcuate faults and controls on hydrocarbon accumulation in the Tiantai slope, Xihu Depression, East China Sea basin

The strike-slip movement of NW-trending transfer zone in the Tiantai slope of the Xihu Depression governed the development of the Cenozoic arcuate faults. These faults significantly influenced trap formation, sand-bodies distribution, and hydrocarbon migration. Based on seismic, drilling data and fault activity analysis methods, this paper describes the origin and evolution of the arcuate faults and their impact on hydrocarbon accumulation. These arcuate faults exhibit a change from NE to NW strike orientation in plan view, and are distributed in the hanging wall of the NW-trending basement faults. The main arcuate faults penetrate the bottom of the Cenozoic strata and extend upward through the top of the lower member of the Huagang Formation, markedly affecting the depositional dynamics of the Pinghu Formation. The segments of the arcuate faults began to grow during the Middle Eocene, and experienced hard linkages in the Late Eocene. The activity of these arcuate faults diminished significantly and gradually stopped during the Middle and Late Oligocene. The segmentation and linkage growth processes of the arcuate faults controlled the formation and evolution of traps. Additionally, the activities of these faults influenced the distribution of sandbodies, with the segmentation points of the arcuate faults serving as important conduits for sediment input. Moreover, the arcuate faults served as effective pathways for vertical hydrocarbon migration. The area with the arcuate faults present favorable conditions for hydrocarbon accumulation in the Tiantai slope of the Xihu Depression.

Comparison of upward and downward flow in high-pressure bulk CO2 gas adsorption on NaY zeolite fixed bed

Adsorption is an appealing technology for the removing of CO2 from natural gas because it can handle high CO2 concentrations at high pressures. The determination of mono-component breakthrough curves provides heat and mass transfer parameters to assess separation effectiveness that can be used for simulation of swing adsorption separation processes (PSA, TSA etc.). However, in lab-scale fixed-bed adsorption, it may be challenging to perform this assessment due to low flow conditions that are usually employed, affecting the flow regimedepending on the operation conditions. In this sense, this work aimed to evaluate the effect of flow regime configurations and difference in gases densities by means of residence time distribution (RTD) analysis in the PSA of CO2 in a NaY zeolite fixed bed , in order to to collect information that satisfy pipeline specifications in industrial applications. A high-pressure lab-scale apparatus was used with NaY particles of 0.7250 mm mean diameter, a 10.5 cm bed height , and a tubular column of 2.0 cm internal diameter. The upward and downward flows were conducted under 528.82 ± 4.59 NmL min−1 inlet mass flow rate, 51 bar, and 30 °C. The RTD analysis was performed to verify the flow regime, and mass transfer zone (MTZ) length was estimated. It was observed that downward flow conditions promoted higher concentration spread than upward flow. RTD analysis showed that downward flow is dominated by laminar convection while the upward flow is dominated by dispersion. MTZ length increased from 0.64 cm in upward flow to 5.81 cm in downward flow. Therefore, assessing CO2 flow conditions and, additionally, the difference in gases densities, are important steps that should be taken when dealing with fluid adsorption under high pressure because different densities between fluid components severely changed and affected flow regime and, consequently, separation effectiveness.

Oily Wastewater Treatment by Using Fe3O4/Bentonite in Fixed-Bed Adsorption Column

Oily wastewater is a major environmental issue resulting from different industrial and manufacturing activities. Contaminated water with oil represents a significant environmental hazard that can harm numerous life forms. Several methodologies have been tested for the removal of oily wastewater from aqueous solutions, and adsorption in a flow-through reactor is an effective mechanism to reduce these effluents. This study focuses on evaluating the ability of Fe3O4/Bent material to adsorb gasoline emulsion from a solution using a fixed-bed column, and it involves analyzing the resulting breakthrough curves. The FT-IR, SEM, EDX, and XRD techniques were used to characterize Fe3O4/Bent. Various ranges of variables were examined, including bed height (2–4 cm), flow rate (3–3.8 mL/min), and initial concentration (200–1000 mg/L), to determine their impacts on the mass transfer zone (MTZ) length and the adsorption capacity (qe). It was shown that a higher bed height and a lower flow rate contributed to a longer time of breakthrough and exhaustion. At the same time, it was noted that under high initial gasoline concentrations, the fixed-bed system rapidly reached breakthrough and exhaustion. Models like the Yoon–Nelson and Thomas kinetic column models were employed to predict the breakthrough curves. Thomas and Yoon–Nelson’s breakthrough models provided a good fit for the breakthrough curves with a correlation coefficient of R2 > 0.95. Furthermore, with a fixed-bed system, the Thomas and Yoon–Nelson models best describe the breakthrough curves for gasoline removal.

Flexural behavior and design of aluminum alloy portal frame eaves joints

Aluminum alloy portal frames (AAPFs) are suitable for both long-term and temporary buildings owing to their light weight, ease of installation and disassembly, and excellent corrosion resistance. Due to the critical importance of joint mechanical behavior for structural safety, this paper conducted experimental and numerical studies on the flexural behavior of AAPF eaves joints. Initially, bending tests on four AAPF eaves joints revealed three failure patterns: connection plate, column, and hole wall failure. The failure patterns are determined by the weakest of these three components. Adding haunches increased the bending zone area, thereby increasing the ultimate bearing capacity by 110 % compared to joints without haunches. Furthermore, strain curves indicated that the load transfer zone was subjected to a bending-shear force state, consistent with the principle that the bolt group shear forms a force couple to transfer the moment. Subsequently, a finite element (FE) model was developed and validated to provide a foundation for subsequent parametric studies and theoretical analysis. The parametric analysis considers bolt diameter, connection plate thickness, aluminum alloy web thickness, and bolt end distance. The bearing capacity corresponding to three failure patterns was discussed, and a design method for the flexural bearing capacity was proposed. The design method for stiffness model was also proposed based on the component-method and parametric analysis. Finally, this paper presented and validated the design steps for the flexural behavior of the eaves joints throughout the whole process, providing an important reference for engineering design.

Experimental study of high-pressure ultrasound-assisted oxidative desulfurization (UAOD) and sulfone adsorption/desorption using zeolite-13X

The sulfurous compounds in natural gas liquids should be reduced to the extent of satisfying the standard recipes due to corrosion, poisoning of catalysts in downstream processes, reduction in the quality of hydrocarbon products and environmental issues. Ultrasound-assisted oxidative desulfurization is an emerging method for sulfur removal from natural gas liquids. Since natural gas liquids exist in the liquid form of hydrocarbons at high pressures and ambient temperature (25 °C), this work aims to investigate the optimal conditions governing ultrasound-assisted oxidative desulfurization for various sulfurous compounds including mercaptan, sulfide and thiophene at high pressure and finally to appraise the adsorption of oxidized sulfurs and the regeneration of the adsorbent using elution with hot water. So, the effects of sulfur content and ultrasonication time were evaluated at 30 bar. Results showed that as the initial sulfur concentration in normal heptane was increased from 0.00 to 3000 ppmS, the sulfur removal efficiency was enhanced by less than 2 % of 95.9 % and of course, the increased ultrasonication time improved the sulfur removal efficiency. Next, results of the sulfone adsorption using zeolite-13X at 30 bar in continuous mode confirmed that the breakthrough time was reduced from 63 to 12 min as the weight hourly space velocity was increased from 5 to 20 h−1 and pursuantly, the mass transfer zone diminished. Besides, the breakthrough time decreased by 45 - 10 min for increasing the initial sulfur content from 200 to 1000 ppmS. Changing the pressure of the adsorption process from 1 to 30 bar caused the improvement of sulfone adsorption capacity by approximately 3.75 times. In continued, the regeneration of zeolite-13X contaminated with sulfone by flowing hot water was evaluated and the zeolite-13X bed was completely regenerated.

Crustal extension and necking at central Campos rifted margin: The Marlim Detachment System

Detachment faults play a crucial role in accommodating crustal thinning and controlling basin architecture in extensional tectonic settings. This study focuses on the characterization of extensional structures at the Necking Domain of the central Campos Rifted Margin, southeast Brazil. Based on seismic reflection and magnetic data we interpreted a system of long offset detachment faults, here named as the Marlim Detachment System. This system is characterized by three distinct large-displacement detachment faults which systematically root at subhorizontal intracrustal reflectors, interpreted as middle crust ductile shear zones, indicating a depth-dependent accommodation of extensional strain. The detachment fault systems resulted in highly tilted upper crustal blocks, which lead to intense erosion of the footwall and the pre-salt sequences eastward. The large horizontal displacement of the hanging wall blocks by most of the detachment faults created deep and wide half-grabens resulting in thick syn-rift sedimentary wedges. The basement structural framework seems to reflect a northward strike-rotation from NE-to NS-direction of the fault systems. That rotation promoted the segmentation of the Marlim Detachment System and points out an oblique-slip extensional kinematics during rifting. We propose that the observed tectonic style at the Necking Domain of central Campos is the result of its interaction with the Vitória-Colatina Transfer Zone to the north and the Araruama Transfer Zone to the south, configuring the Marlim area as a structurally transition zone. The tectonostratigraphic analysis suggests a migration of the deformation from continent to ocean from Hauterivian to Aptian, and a polyphase and/or tardi-tectonic deformation of the Necking Domain in the central Campos Rifted Margin.

Experimental study on heat storage characteristics of an air-sand moving bed heat exchanger

The air-sand moving bed heat exchanger, designed for storing fluctuating medium-temperature gas waste heat, offers significant potential for energy conservation and carbon reduction in industrial settings. However, its operational characteristics are insufficiently explored. This study investigates the heat storage process involving direct contact and cross-flow of air and quartz sand within a rectangular heat exchanger chamber. Comprehensive analyses were conducted to explore flow resistance characteristics, temperature response, and heat storage performance. Results indicate that pressure drop increases with higher air velocity and temperature, and lower air pressure, particle diameter. The relative discrepancy between fitted pressure drops and experimental data is below 10%. The primary heat transfer zone exists during particle descent. As the air-particle mass flow ratio increases, the descent rate of this zone along the airflow direction slows. Additionally, higher air temperatures elevate the optimal air-particle mass flow ratio. With inlet temperatures for air and particles set at 350 °C and 30 °C respectively, and a mass flow ratio of 0.81, an exergy efficiency of 58.93% and a power density of 600.64 kW·m−3 are achieved. These findings offer crucial insights for air-sand moving bed heat exchangers for medium-temperature gas waste heat recovery.

Purification of industrial toluene from technical to reagent grade using Diahope activated carbon in a pilot-scale fixed-bed column

The removing organic impurities from technical-grade toluene (99.1 %) to produce reagent-grade toluene (99.9 %) has been addressed by assessing the mono- and multi-component adsorption of methylbenzothiophene (MBT), ethylcyclopentane (ECP), and xylene (XYL), which represent sulfur, non-aromatic, and aromatic impurities, respectively. Laboratory-scale static-experiments conducted between 10 and 30 °C showed that although toluene sorption on granulated activated carbon (GAC) is exothermic, the sorption capacity for each impurity increased with temperature, indicating endothermic sorption for the impurities. The sorption behavior for MBT and ECP followed the Langmuir model while for XYL followed the Freundlich model with the order of sorption affinity as MBT > ECP > XYL. In pilot-scale dynamic-experiments, the breakthrough curves (BTCs) were evaluated under various bed heights (60 and 120 cm), flow rates (1–3 L min−1), sorbate inlet concentrations (200–400 mg L−1), and optimal temperature (30 °C) obtained in static experiments. In mono-component sorption, the highest sorption capacities for MBT, ECP, and XYL were 97.1, 70.7, and 65.4 mg g−1, respectively, while the corresponding values were 46.0, 43.0, and 22.9 mg g−1 respectively, in multi-component sorption under the same operating conditions. A CFD simulation in COMSOL (v.6.2) revealed sharper BTCs with time delay compared to the experimental data while a good correlation (R2 > 0.99) was observed for BT models. The narrower mass transfer zone for MBT and ECP compared to XYL indicated more effective sorption of these sorbates, respectively. Regenerating GAC up to four cycles with hot N2 (80 °C) showed a satisfactory sorption capacity for industrial toluene impurities, indicating a reversible sorption–desorption process with a cumulative sorption usage rate of 5.5 g L−1. The pilot-scale set-up used in this study successfully purified a large volume (∼475 L) of industrial toluene.

Exploration of the adsorption and desorption performance of volatile organic compounds by activated carbon with different shapes based on fixed-bed experiments

Activated carbon (AC) has been widely used in volatile organic compounds (VOCs) treatment of industrial exhaust gases. Rather than modifying specific pore size distributions and surface properties, altering the shape of AC offers a more feasible approach to enhance its adsorption performance. This study investigates the adsorption-desorption performance of two different shaped ACs with highly similar properties for the removal of VOCs. The clover-shaped AC (CSAC) has a 27.46% lower internal void fraction and a 39.10% higher external void fraction compared to cylindrical AC (CAC), resulting in denser packing and longer contact time with VOCs. Adsorption experiments showed the CSAC has 40% longer adsorption breakthrough (BT) times for ethanol, ethyl acetate, and n-hexane on average, and 20% higher saturation adsorption capacity per unit volume. CSAC also has higher partition coefficients, with the highest values for ethanol, ethyl acetate, and n-hexane being 0.0187, 0.0382, and 0.0527 mol kg−1·Pa−1, respectively. The desorption process for selected VOCs is non-spontaneous and endothermic. Optimal desorption conditions were identified as an inlet space velocity of 3535 h−1, a desorption temperature of 150 °C, and a pulsed inlet method. To investigate the possibility of the application of CSAC in real-world scenarios, xylene was chosen as a representative industrial VOC. Results showed CSAC has 20% higher BT time and saturation adsorption capacity for xylene compared to CAC under different bed heights. The desorption efficiency for xylene on both ACs is below 40%. With increasing xylene inlet concentration, the mass transfer zone (MTZ) height initially increases but stabilizes beyond 1704 mg m−3. At identical bed heights, the MTZ height of CSAC is 29% shorter than CAC, indicating a higher bed utilization efficiency.

Efficient removal of environmentally hazardous heavy metal ions from water by NH2-MIL-101-Fe and MOF-808-EDTA based polyether sulfone adsorbents

The potential of metal–organic frameworks (MOFs) based polymeric composites for heavy metal removal was analyzed in this study. Two mixed matrix composites, along with NH2-MIL-101-Fe and MOF-808-EDTA, were synthesized. The MOFs were synthesized using the solvothermal method, and the mixed matrix spheres (MMSs) were prepared using the facile dropping method. The MMSs were characterized, and batch adsorption studies were performed at different pH and adsorbent dosages. For both MMSs, the optimum pH was between 5–5.5, and the highest removal rates were obtained for MOF-808-EDTA spheres (94 % Hg2+, 86 % As, 80 % Mn). The optimum adsorbent dosage for MOF-808-EDTA was found to be 5.42 g/L, while for NH2-MIL-101-Fe, it was 7.13 g/L, after which the metal ion removal efficiency was reduced. Langmuir adsorption isotherm was fitted with thermodynamic evaluation of Gibbs free energy, enthalpy, and entropy. MOF-808-EDTA demonstrated a greater adsorption capacity of 272.7 mg/g (Hg2+), 151.29 mg/g (As3+), and 125.9 mg/g (Mn2+) than the other MMP. The Gibbs free energy of −20.14 (Hg2+), −12.66 (Mn2+), and −52.61 kJ/mol (As3+) were obtained from the thermodynamic study. The results indicated that the process was exothermic and spontaneous. Breakthrough column studies were performed for MOF-808-EDTA spheres using the pore-surface-diffusion model. The transient column study was conducted for individual heavy metal ion solutions using Addesign™ software to evaluate column exhaustion time, breakthrough time and length of mass transfer zone. Studies with multicomponent solutions of heavy metals also gave potentially promising results in the separation of 92 % of Hg, 84 % As, and 75 % Mn which indicates the prepared adsorbents can be used to remove heavy metal ions from industrial wastewater samples.

Effects of aggregate's type and orientation on stress concentration and crack propagation of modeled concrete applied a shear force

This study focused on planarizing natural modeled aggregate concrete (NMC), recycled modeled aggregate concrete (RMC), and brick modeled aggregate concrete (BMC) for analyzing the influences of aggregates on shearing failure mechanism. A designed apparatus was used to load a shear force for the specimens and analyzed the global and local strain fields near the interface transition zone (ITZ) using digital image correlation (DIC) analysis. Additionally, we employed COMSOL software simulation to understand the crack initiation process and damage evolution mechanism of related concrete. Our findings revealed that the brick aggregate leaded to the lowest modulus of elasticity and compressive strength, resulting in poor shear resistance. However, the recycled aggregate model exhibited the highest shear resistance, primarily due to the old mortar acting as a buffer layer in the ITZ. During loading, the stress in the NMC model concentrated in the load transfer zone and gradually moved to the left and right sides of the built-in aggregate model until fracture, as observed through DIC analysis. The stress distribution of the RMC was similar with those of the NMC, but the BMC showed a distinct stress distribution pattern. Furthermore, the corner of the built-in modeled aggregate significantly influenced the crack propagating path and stress distribution. Therefore, the modeled aggregate corner plays a crucial role in the shear behavior of concrete, affecting both crack propagation and overall mechanical performance. The practical implications of our study can inform the design and application of recycled concrete.

A Failed Rift in the Eastern Adventure Plateau (Sicilian Channel, Central Mediterranean)

Widespread volcanism has been known in the Sicilian Channel for a long time, even if some submarine volcanoes have only recently been discovered. Most of this volcanism formed along the NNE-trending transfer zone known as the Capo Granitola–Sciacca Fault Zone, while others, such as the islands of Pantelleria and Linosa, are associated with the continental rift zone that has developed since the early Pliocene in the central part of the Sicilian Channel through the formation of three deep tectonic troughs (Pantelleria, Linosa and Malta). However, the origin of a group of five volcanoes (here called “Tetide volcanic cluster”) that form a NW-SE alignment on the eastern edge of the Adventure Plateau is not yet known. In this work, we hypothesize that this volcanic alignment may represent the remnants of a failed rift attempt that was unable to generate another tectonic trough in the Sicilian Channel. Based on seismic sections and gravimetric data, three phases in the formation of this volcanic alignment can be identified: (i) a major magmatic intrusion in the early Pliocene associated with a NW-SE normal fault that formed during the opening of the Pantelleria graben, leading to the uplift and deformation of the host sedimentary rocks; (ii) a late Pliocene-Quaternary tectono-magmatic quiescent phase; and (iii) a renewed magma intrusion through fissures or cracks that led to the formation of the volcanoes in the late Quaternary. This process was not able to cause significant extension and only limited volcanism, which is why the “Tetide volcanic cluster“ is interpreted as the morphological expression of a failed rift.

Complex Segment Linkage Along the Sevier Normal Fault, Southwestern Utah

Abstract Major normal fault systems are composed of segments that link as displacement accumulates, with linkage zone characteristics that reveal fault zone evolution. The steeply west-dipping Sevier fault zone in southwestern Utah, displays a complex fault network that developed between two long (>10 km), en echelon segments near the town of Orderville. Geologic map data and cross-sections of the transfer zone between the Mt. Carmel segment in the south and the Spencer Bench segment in the north reveal more than ten normal faults and four relay ramps displaying a range of geometries, including two relay ramps that display ramp-parallel folds. We suggest that transfer zone deformation was initially dominated by faults subparallel to the primary segments with later cross-faults that hard-linked these faults across most of the transfer zone. When the transfer zone was a soft-linked system, a displacement deficit likely existed relative to fault segments to the north and south. This early fault configuration would have reduced the efficiency of slip propagation associated with major earthquakes (>M7.0). In contrast, the present-day transfer zone, with a complex but hard-linked fault network, shows displacements that transition smoothly from the higher displacement (~800 m) southern segment to the lower displacement (~400 m) northern segment. That transition, combined with extensional strain within the zone, suggests that the Orderville fault network would be unlikely to impede propagation associated with future major earthquakes. The kinematic model of fault evolution presented here has implications for those investigating geothermal energy potential, groundwater flow, natural gas and oil reservoirs, mineral deposit formation, or seismic hazards.

Adsorption studies on synthetic lentil-like mordenite for column and batch removal of cadmium and lead ions: investigating isotherms and kinetics

ABSTRACT The mordenite zeolite adsorbent, with a lentil-like structure, was synthesised using a one-step green hydrothermal method. Its textural, structural, and morphological properties were characterised through X-ray diffraction (XRD), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, and the Brunauer-Emmet-Teller (BET) method. The prepared adsorbent was employed in both continuous and batch adsorption processes to remove toxic Cd(II) and Pb(II) metal ions from aqueous solutions. Operational parameters such as flow rate, initial concentration, and bed height were varied to understand breakthrough time, mass transfer zone, adsorption capacity, and exhaustion time during continuous adsorption, which were investigated and optimised. Additionally, the study explored the influence of solid/liquid ratio, pH, assay time, and initial concentration on batch adsorption. The maximum adsorption capacities of the lentil-like mordenite zeolite in fixed-bed breakthrough experiments were determined to be 78.22 mg/g for Cd (II) ions and 80.82 mg/g for Pb (II) ions. In batch experiments, the capacities were 133.64 mg/g for Cd (II) ions and 239.57 mg/g for Pb (II) ions. Dynamic continuous adsorption isotherms exhibited an excellent fit with the Thomas and Yoon – Nelson models, while batch adsorption isotherms conformed well to the Langmuir model. This study presents a new approach for synthesising high surface area, engineered morphology, reusable, and stable zeolite for effectively adsorbing hard metal ions from wastewaters, contributing to environmental remediation.

Recovery and concentration of Eu(III) from phosphogypsum leachate using ouricuri endocarp

Ouricuri endocarp was utilized as a biosorbent for the recovery of europium (Eu(III)) from aqueous solutions and rare earth elements (REEs) from authentic leachate derived from phosphogypsum, which encompasses various REEs. Various characterization techniques were applied to analyze the physicochemical and adsorptive properties of the biosorbent. The results indicate that the adsorption kinetic data conform well to the pseudo-first-order model, while the Liu model describes the equilibrium data well. Ouricuri endocarp and Eu interactions are favorable and spontaneous. The maximum adsorption capacity for Eu(III) is determined to be 22.9 mg/g according to the Liu model. Based on experimental results and adsorbent characteristics, the proposed adsorption mechanisms between ouricuri endocarp and Eu include ion exchange and electrostatic interactions as the primary mechanisms. The Eu(III) recovery is also feasible as a continuous flow process demonstrating inclined breakthrough curves and lower values of the length of the mass transfer zone. Ouricuri endocarp demonstrates its selectivity for recovering various REEs from authentic phosphogypsum leachate. It achieves a 98% recovery rate for Eu and approximately 60% for Ce, La, and Nd, affirming its efficacy under real-world conditions. Finally, concentration of REE was done by ashing loaded ouricuri endocarp, and a solid with around 34% (in weight) of REE is obtained.

The Spatial and Temporal Distribution, Flow Network and its Characteristics of Population in Henan Province

Based on the WorldPop center population data set and the dynamic monitoring data of China 's floating population, this paper analyzes the spatial and temporal changes of regional population and the characteristics of flow network and its influencing factors with the help of ArcGIS spatial analysis and mapping function and geographic detector model. It shows that: The regional difference of population spatial distribution in Henan Province is obvious and extremely uneven, and the population agglomeration speed of Zhengzhou metropolitan zone is obviously accelerated. The regional differentiation of population change in Henan Province is serious, and the population attraction of Zhengzhou is increasing, The population of Undertake industrial transfer zone such as Shangqiu and Zhoukou continued contraction. The population growth area and the population contraction area are more concentrated in space, showing the characteristics of spatial agglomeration. In addition, economic factors are still the main driving factors of population change in Henan Province. The influence of service industry on population change is increasing, and the explanatory power of traditional agriculture, forestry, animal husbandry and fishery and manufacturing industry on population change is decreasing. The integrated development of secondary and tertiary industries will further affect the future population distribution pattern of each region.

Removal of V(V) from a Mixed Solution Containing Vanadium and Chromium Using a Micropocrous Resin in a Column: Migration Regularity of the Mass Transfer Zone and Analysis of Dynamic Properties

Removal of V(V) from a Mixed Solution Containing Vanadium and Chromium Using a Micropocrous Resin in a Column: Migration Regularity of the Mass Transfer Zone and Analysis of Dynamic Properties