Saturation Loading Research Articles

Deposition of Imidazole into Mesoporous Zirconium Metal-Organic Framework for Iodine Capture.

Efficient capture of radioiodine is essential for the protection of the ecological environment and the sustainable development of nuclear energy generation. Metal-organic frameworks (MOFs) and their derivatives provide alternative potential for overcoming the limitations of traditional iodine adsorbents. Herein this work, imidazole (Im) is dispersed into a robust mesoporous zirconium MOF PCN-222 by the heat deposition method, forming a high-uniformity composite Im@PCN-222. The large pore size and marked chemical resistance skeleton of PCN-222 allow the incorporation of Im to reach 43 wt % while surviving the chemical corrosion of activated Im. The nearly saturated loading of Im significantly benefits the sorption capability toward iodine and gives rise to an exceptional adsorption capacity of 10.04 g g-1 and excellent recyclability. This value is higher than that of most of the MOFs and their derivatives. Further, Im was also successfully deposited onto the PCN-222 functionalized porous Al2O3 ceramic filtration membrane, which endowed the hybrid membrane with efficient iodine sorption and separation properties. This work highlights a new strategy for the fabrication of the MOF-based radioiodine adsorption composite as well as MOF composite-based filters.

Influence of partial saturation and organic loading on the performance of vertical wetlands for raw wastewater treatment

Influence of partial saturation and organic loading on the performance of vertical wetlands for raw wastewater treatment

Assessing swelling-induced damage in shale samples during triaxial testing

In shale testing, understanding the impact of effective stress and saturation conditions is crucial for accurate material behaviour assessment and parameter determination. In some cases, saturation in triaxial testing starts at low effective stress before ramping up for shearing. However, when in contact with water (or saline water), shales are prone to swelling, particularly at low effective stress levels, which can induce fissures and alter material properties. This study investigates the influence of fluid saturation strategies and stress/pressure variations on the mechanical behaviour of shales, particularly under low effective confinement. Building upon the comprehensive testing campaign (>140 tests) in Crisci et al. (2024), additional tests were conducted on Opalinus Clay shale, focusing on sample saturation methods and loading histories before shearing. The conditions under which tested specimens experience damage were detected through diagnostic indicators such as differences in stress path and lower strength and stiffness compared to intact specimens with identical basic properties. Micro CT scanning confirms that damage is related to the development of fissures. The volumetric changes in specimens were quantified throughout the testing phases and thresholds for tolerable strains and effective stresses, specific to this material, were established. Comparative analysis with Opalinus Clay from shallower depths and other shales globally revealed consistent findings. Notably, it is shown that, for all shale types analyzed, a linear failure envelope emerges in the low to intermediate effective stress regime when filtering out "damaged" specimens. This suggests that non-linear failure envelopes observed in some cases may stem from exposing specimens to low effective stress before shearing.

Performance and energy evaluation of dynamic adaptive deterministic routing algorithm for multicore architectures

Chip Multiprocessors (CMPs) leverage multiple processing units to improve computational speed and efficiency. Routing algorithms in NoC (Network-on-Chip) architectures ensure efficient data communication between these units, addressing challenges such as congestion, latency, and power consumption. This paper delves into an extensive analysis of the performance evaluation concerning the Dynamic Adaptive Deterministic (DyAD) routing for Network-on-Chip (NoC) and Wireless Network-on-Chip (WiNoC) configurations within the framework of a 64-core and 100-core multicore architecture. The evaluation involved a congestion threshold analysis of data transmission latency, the efficiency of network data throughput, and the amount of energy consumed. To substantiate our conclusions, we conducted simulations of the 64-core and 100-core mesh-based NoC and WiNoC architectures under the Video Image Processing System (VIPS) benchmark workload. These simulations were executed utilizing the Noxim simulator, a well-recognized tool acclaimed for its capacity to provide cycle-accurate simulations. Analyzing the simulation outcomes, it becomes evident that the DyAD routing approach for the 64-core and 100-core WiNoC architecture performs better in terms of network performance. It is characterized by enhanced capabilities at higher Packet Injection Rate (PIR) saturation loads, improved network throughput, and minimized latencies. This dominance is evident from its ability to handle heavier workloads and achieve lower delays in the investigated VIPS workload situations, compared to the 64-core and 100-core NoC multicore architecture.

Long-chain fatty acids facilitate acidogenic fermentation of food waste: Attention to the microbial response and the change of core metabolic pathway under saturated and unsaturated fatty acids loading

Long-chain fatty acids (LCFAs) are recognized as a significant inhibitory factor in anaerobic digestion of food waste (FW), yet they are inevitably present in FW due to lipid hydrolysis. Given their distinct synthesis mechanism from traditional anaerobic digestion, little is known about the effect of LCFAs on FW acidogenic fermentation. This study reveals that total volatile fatty acids (VFAs) production increased by 9.98 % and 4.03 % under stearic acid and oleic acid loading, respectively. Acetic acid production increased by 20.66 % under stearic acid loading compared to the control group (CK). However, the LCFA stress restricted the degradation of solid organic matter, particularly under oleic acid stress. Analysis of microbial community structure and quorum sensing (QS) indicates that LCFA stress enhanced the relative abundance of Lactobacillus and Klebsiella. In QS system, the relative abundance of luxS declined from 0.157 % to 0.116 % and 0.125 % under oleic acid and stearic acid stress, respectively. LCFA stress limited the Autoinducer-2 (AI-2) biosynthesis, suggesting that microorganisms cannot use QS to resist the LCFA stress. Metagenomic sequencing showed that LCFA stress promoted acetic acid production via the conversion of pyruvate and acetyl-CoA to acetate. Direct conversion of pyruvate to acetic acid increased by 47.23 % compared to the CK group, accounting for the enhanced acetic acid production under stearic acid loading. The abundance of β-oxidation pathway under stearic acid loading was lower than under oleic acid loading. Overall, the stimulating direct conversion of pyruvate plays a pivotal role in enhancing acetic acid biosynthesis under stearic acid loading, providing insights into the effect of LCFA on mechanism of FW acidogenic fermentation.

Analisis Perbandingan Biaya dan Waktu pada Penggunaan Duct Spacer dengan Prefabricated dan Hollow Baja Ringan Untuk Pekerjaan Underground Ducting

The Kediri Airport development project encountered challenges related to underground ducting work. The design of Kediri Airport adheres to international standards, which led to the use of materials not readily available in Indonesia, specifically pipes and duct spacers. Duct spacers are tools used to arrange ducting pipes according to their formation and prevent them from floating during concrete pouring due to buoyancy. The SKEP/114/VI/2002 serves as a reference for underground cable installation, involving direct burial of cables at a depth of 70 cm, covered with a 5 cm layer of sand above the cable surface. These two approaches significantly differ, necessitating problem-solving solutions. To address this issue, research was conducted to find suitable duct spacers in Indonesia. Two alternative materials were considered: PVC and lightweight hollow steel. The study compared costs and time associated with these materials. PVC duct spacers would be imported and be fabricated in Indonesia, while hollow steel duct spacers would be fabricated on-site. The research focused on three aspects: ducting work methods, duct spacer design, and cost-time analysis. Given tight installation spaces and busy schedules, duct spacers needed to be compact, simple, and adaptable to various pipe formations. The design for hollow steel duct spacers aimed for simplicity to reduce on-site construction work. However, care was taken to avoid potential injuries from exposed bolts on the hollow steel frame. The PVC duct spacer design utilized Polytam PF 1000 material, with a nominal shear strength of 399 kg and a nominal moment of 266 kg·cm—sufficient to withstand saturated soil loads up to 162 cm but not vehicular loads. Analyzing procurement time, PVC duct spacers from Indonesian manufacturers were the quickest, taking only 56 days due to no port clearance delays. The fastest completion time for the project was achieved using PVC duct spacers, taking 122 seconds—three times faster than hollow steel duct spacers. While lightweight steel was the most cost-effective option for on-site procurement, combining cost and time analysis favored PVC duct spacers. The minimal cost difference allowed for accelerated production, minimizing the risk of delays

Optimal saturated information load analysis for enhancing robustness in unmanned swarms system

Saturated information load is defined as the information received by a unmanned aerial vehicle (UAV) node in a swarm network reaches the overload limit of its processing capability. When a UAV swarm performs a mission in an uncertain and adversarial complex environment, overloading of UAVs will lead to information diversion, which may cause other UAVs to experience overloading and diversion as well, affecting the transmission efficiency and robustness of the entire swarm network, which in turn affects the information sensing ability, execution ability, and coordination ability of the swarm in performing the mission. Therefore, this paper proposes a saturated information load-based UAV swarm network topology modelling method, which sets the saturated information load of the nodes in the network model in order to reasonably allocate network resources and optimise the network topology. In addition, through robustness experiments of complex networks and comparative analysis of different saturated information loads and three typical modelling methods, the saturated information load-based network structure modelling method has outstanding advantages and performance in terms of network connectivity, network communication efficiency, and destruction resistance.

A quantitative study of the effects of physical properties and external loads on the liquefaction of saturated sand based on an intelligent numerical cyclic triaxial test system

ABSTRACT Soil liquefaction would cause significant damage to the safety of cargo transportation. The aim of this article is to conduct a quantitative study of the influence of the main physical characteristic parameters of saturated sand and external loads on its liquefaction. On the basis of the physical cyclic triaxial test (CTT), the finite element simulation model and PSO-BP neural network prediction model and importance analysis model were optimised in this study. Based on this, an innovative intelligent numerical CTT system for saturated sand was constructed. The research results indicate the influence of external load, effective internal friction Angle and plasticity index on the liquefaction of saturated sand is significant, and the average weight is 40.15%, 29.15% and 25.05%, respectively. In this paper, the relevant research provides a theoretical basis for effective control of sand liquefaction and provides new ideas and feasible solutions for subsequent research on sand liquefaction.

Adjusting the phase transition time node of a solid–liquid biphasic solvent based on 2-amino-2-methyl-1-propanol for efficient CO2 capture: Insight into the regulatory effect of aminoethylethanolamine

Solid-liquid biphasic solvents (SLBSs) hold promise as energy-efficient candidates for CO2 capture. Nevertheless, the premature phase transition of current SLBSs leads to inopportune solid precipitation, posing operational challenges for the CO2 capture system. This study proposed a promising strategy that using aminoethylethanolamine (AEEA) as a regulator to fine-tune the phase transition time node of the 2-amino-2-methyl-1-propanol (AMP)/N-methylpyrrolidone (NMP) SLBS, enabling the phase transition to occur precisely as desired. Experimental results showed that the AEEA/AMP/NMP (A/A/N) SLBS exhibited tunable phase transition time nodes, modulated by the concentration of AEEA. Specifically, with the addition of 0.2 mol·L−1 AEEA, the CO2 loading associated with the phase transition increased significantly, from 0.19 to 0.54 mol·mol−1, approaching the saturation loading of 0.57 mol·mol−1. The delayed phase transition would facilitate the CO2 absorption operation. The regulatory mechanism of AEEA on the phase transition were thoroughly studied via 13C NMR and quantum calculations. AMP reacted with CO2 to produce AMPCOO− and AMPH+, which had a significantly stronger affinity for each other than for the solvent NMP, mediated by strong hydrogen bond interactions. Consequently, the continuous and fast aggregation of AMPCOO− and AMPH+ caused their swift precipitation from NMP. With the introduction of AEEA, the derived product AEEAH+(S)COO–(P) acted as a bridge-builder, connecting AMPCOO− or AMPH+ and NMP via hydrogen bonds, increasing the solubility of the AMP-derived products in NMP, thus effectively delaying the phase transition. Thermodynamic analysis revealed that the A/A/N SLBS exhibited a total regeneration energy consumption of 1.94 GJ·ton−1 CO2, representing a significant reduction of 48.9 % compared to that of 30 wt% MEA. This study provided a novel idea for designing SLBSs with controllable phase transition behavior, and offered a promising A/A/N SLBS for energy-efficient CO2 capture.

A Study on the Critical Saturation Response Characteristics of Simple and Sandwich Cylindrical Shells under Long-Duration Blast Loading.

Experimental research and numerical simulations of the structural response to shock waves with pulse durations of hundreds of milliseconds, or even seconds, are extremely challenging. This paper takes typical single-layer and sandwich cylindrical shells as the research objects. The response rules of cylindrical shells under long-duration blast loadings were studied. The results show that when the pulse duration is greater than or equal to 4~5 times the first-order period of the structure, the maximum response of the structure tends to be consistent, that is, the maximum response of the cylindrical shells with different vibration shapes shows a saturation effect as the pulse duration increases. This study established the relationship between the saturation loading time and the inherent characteristics of the structure. It was found that the saturation effect was applicable under the following conditions, including different load waveforms, elastic-plastic deformation of the structure, and the loading object being a sandwich shell. This will help transform the long-duration explosion wave problem into a finite pulse-duration shock wave problem that can be realized by both experiments and numerical simulations.

Peak shaving potential and its economic feasibility analysis of V2B mode

Electric vehicles (EVs) as mobile energy-storage devices improve the grid's ability to absorb renewable energy while reducing peak-to-valley load differences. With a focus on smoothing the load curve, this study investigates the peak shaving potential and its economic feasibility analysis of V2B mode. First, based on the virtual microgrid system established in this paper, a Monte Carlo method was used to simulate the driving, charging, and discharging processes of EVs. Second, the effects of the number of charging stations, battery capacity of EVs, and photovoltaic (PV) penetration rate on the peak shaving results were evaluated separately by using the standard deviation of daily loads. Third, the V2B peak shaving strategy and cost composition were explored considering the battery aging costs. Moreover, the economic feasibility and factors influencing the proposed strategy were analyzed. The results indicate that 1) V2B effectively transfers peak power loads between 08:00 h And 20:00 h To low-demand periods at night; 2) as the deployment ratio of charging station increases, the level of load fluctuation decreases significantly. When EV battery capacity is at or above 60 kW h, charging station deployment ratios of 0.43, 0.42, and 0.47 are required for saturated load smoothing in winter, transition period, and summer, respectively; 3) the PV penetration rate for maximizing the collaborative peak shaving capability of V2B and PV power is 30%–40 % and 4) reducing battery costs or extending battery life has the most significant effect on V2B power costs, followed by charging station costs. This study provides a theoretical basis for determining the economic feasibility of charging station planning and provides technical guidance for the rational scheduling of EVs and their friendly interaction with the power grid.

Evaluation of the Limitation of Operational Parameters of the IEEE 802.11 ac Network in the 20MHz Channel

IEEE 802.11 wireless network technologies are widely used to create corporate and personal local networks for data exchange and access to Internet resources. The main principle of operation of IEEE 802.11 networks is the principle of competitive access, according to which all wireless network users have the same access rights to the information transmission environment. This method of access leads to the occurrence of collisions in networks with a large number of users, which complicates the process of network functioning and leads to the degradation of quality indicators. The purpose of the study is to estimate the limit values of the operational characteristics of the IEEE 802.11 ac wireless network in the mode with the highest transmission rate (MCS8) in a frequency channel of 20 MHz with one spatial stream, provided that the network has a significant number of active stations with a saturated load. An alternative model of processes in IEEE 802.11 networks based on the concept of a virtual competitive window is used for research. According to the concept of virtual contention window (VCW), the process of data transmission in a network with competitive access is considered as a quasi-stationary process. Numerical data were obtained and graphs of channel bandwidth, transmission delay, and delay non-uniformity were given in the presence of one to sixteen active stations with a saturated load in the network, in the case of transmission of frames with a data volume of 512 or 1500 bytes. The maximum possible bandwidth of the channel with a frequency band of 20 MHz (68.387 bit/s) was determined, in the case of using frames with the maximum load (11454 bytes) provided by the standard. Estimated data on the number of collisions occurring in a network with a saturated load and the number of frames transmitted at various stages of channel access are also provided. The frame transmission delay increases almost proportionally to the number of active stations and varies from 0.605 ms to 5.293 ms, in the case of loading all data frames of 512 bytes, and from 0.785 to 6.41 ms, in the case of a load of 1500 bytes, for changes in the number of active stations in the network from 2 to 16. The unevenness of the delay exceeds the average delay and grows non-linearly, in the case of an increase in the number of active stations from 1 to 6 (CWmin=15), and linearly — with a further increase in the number of stations (over 6). The obtained results are useful for reasonable planning of wireless networks and configuration of network equipment parameters.

Geospatial Liquefaction Modeling of the 2023 Türkiye Earthquake Sequence by an Ensemble of Global, Continental, Regional, and Event-Specific Models

Abstract A global geospatial liquefaction model (GGLM-2017) was previously developed (Zhu et al., 2017) using logistic regression (LR) and is currently used by the U.S. Geological Survey as the preferred liquefaction model to map liquefaction probability immediately after the occurrence of earthquake events. This research proposes an ensemble modeling approach to improve the performance of the GGLM-2017 for geospatial liquefaction modeling of the 2023 Türkiye earthquakes using an updated inventory of liquefaction occurrence locations in Europe (the OpenLIQ database, which includes prior events occurring in Türkiye) and a new inventory from the 2023 Türkiye earthquakes (gathered from multiple sources). Using the same geospatial proxies for soil saturation, soil density, and earthquake loading, and the same non-liquefaction sampling strategy used to develop GGLM-2017, the proposed ensemble method is validated on the data of the 2023 Türkiye earthquakes by integrating four models, including global (GGLM-2017), continental (LR model trained on eight European events), regional (LR model trained on three historical events in Türkiye), and event-specific (LR model trained on partially available data from the 2023 Türkiye earthquakes) models. The inventory from the 2023 Türkiye earthquakes is split into two batches, in which the first batch (163 liquefaction occurrences) resulted from the preliminary reconnaissance and is used for training the event-specific model, and the second batch (284 liquefaction occurrences) resulted from a more complete reconnaissance (which was made available later) and is used for validating all models. The rationale for using the first batch for training the event-specific model is to exploit the information as they become available to optimize the performance of global model in liquefaction prediction. The final ensemble probability assignment is done by averaging the probabilities derived by the four individual models, and a 50% threshold is used for classification accuracy evaluations. Comparative analysis of the ensemble model’s performance with the GGLM-2017 showed improved predictive accuracy, resulting in higher liquefaction detection for the specific event under study (the 2023 Türkiye earthquakes). The ensemble model also provides an estimate of model uncertainty.

Magnetic composite microspheres with a controlled mesoporous shell for highly efficient DNA extraction and fragment screening.

Rapid extraction and screening of high-purity DNA fragments is an indispensable technology in advanced molecular biology. In this article, mesoporous magnetic composite microspheres (MSP@mTiO2) with tunable pore sizes were successfully fabricated for high-purity DNA extraction and fragment screening. Owing to the strong complexation ability of Ti ions with DNA phosphate groups and the high specific surface area of mesoporous microspheres, the MSP@mTiO2 microspheres possess excellent adsorption performance, where the saturated loading capacity of MSP@mTiO2 with a specific surface area of 122 m2 g-1 is as high as 575 μg mg-1 for a salmon sperm specimen. ITC experiments demonstrated that DNA adsorption on MSP@mTiO2 microspheres is mainly driven by entropy, which gives us more potential ways to regulate the balance of adsorption and desorption. Meanwhile, the mesoporous MSP@mTiO2 microspheres exhibit a much higher extraction efficiency compared with non-porous MSP@TiO2 for whole genome DNA from Arabidopsis thaliana plants. Interestingly, DNA fragments with different lengths could be screened by simply regulating the pore size of MSP@mTiO2 or the concentration of Na3PO4 in the eluent. A small pore size and low phosphate concentration are advantageous for the extraction of short-stranded DNA fragments, and DNA fragments (≤1000 bp) can be efficiently extracted when the mesopore size of MSP@mTiO2 is lower than 7.6 nm. The extraction results from the mesoporous composite microspheres provide new promising insights into the purification and screening of DNA from complex biological samples.

Chemical Activity-Based Loading of Artificial Sediments with Organic Pollutants for Bioassays: A Proof of Concept.

Persistent organic pollutants (POPs) pose a risk in aquatic environments. In sediment, this risk is frequently evaluated using total or organic carbon-normalized concentrations. However, complex physicochemical sediment characteristics affect POP bioavailability in sediment, making its prediction a challenging task. This task can be addressed using chemical activity, which describes a compound's environmentally effective concentration and can generally be approximated by the degree of saturation for each POP in its matrix. We present a proof of concept to load artificial sediments with POPs to reach a target chemical activity. This approach is envisioned to make laboratory ecotoxicological bioassays more reproducible and reduce the impact of sediment characteristics on the risk assessment. The approach uses a constantly replenished, saturated, aqueous POP solution to equilibrate the organic carbon fraction (e.g., peat) of an artificial sediment, which can be further adjusted to target chemical activities by mixing with clean peat. We demonstrate the applicability of this approach using four polycyclic aromatic hydrocarbons (acenaphthene, fluorene, phenanthrene, and fluoranthene). Within 5 to 17 weeks, the peat slurry reached a chemical equilibrium with the saturated loading solution. We used two different peat batches (subsamples from the same source) to evaluate the approach. Variations in loading kinetics and eventual equilibrium concentrations were evident between the batches, which highlights the impact of even minor disparities in organic carbon properties within two samples of peat originating from the same source. This finding underlines the importance of moving away from sediment risk assessments based on total concentrations. The value of the chemical activity-based loading approach lies in its ability to anticipate similar environmental impacts, even with varying contaminant concentrations. Environ Toxicol Chem 2024;43:279-287. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Efficient and Selective Recovery of Gold from Thiosulfate Leaching Solution Using Functionalized β‐Cyclodextrins Synthesized by a Steric Hindrance Strategy

AbstractDesigning suitable adsorbents is a key challenge in the recovery of Au(I) from thiosulfate gold‐leaching solutions as the ideal adsorbent not only possesses abundant active sites with high affinities and selectivities toward Au(I), but also demonstrates fast recovery of Au(I) at high purity and large capacity. Herein, guided by theoretical calculations, a water‐insoluble inclusion complex is synthesized using β‐cyclodextrin (β‐CD) and diphenylphosphine (DPP) as host and guest molecules, respectively, by a steric hindrance strategy for highly efficient and selective Au(I) recovery. The prepared β‐CD@DPP exhibits outstanding Au(I) adsorption performance, with a saturated loading capacity of 146.28 mg g−1. The excellent adsorption performance of β‐CD@DPP for Au(I) is mainly attributed to the full exposure of the adsorption site and the weakly alkaline adsorption environment. Furthermore, β‐CD@DPP demonstrates outstanding selectivity for Au(I) in a Cu─NH3─thiosulfate gold‐leaching solution, and the Au(I) recovery rate is higher than 99%. Synthesis of β‐CD@DPP primarily depends on the weak interactions between DPP and β‐CD. Mechanism of adsorption of Au(I) on β‐CD@DPP involves ligand exchange between PPh2− and [Au(S2O3)2]3−. This study provides a new idea and material preparation method for highly efficient, selective, and large‐capacity recovery of Au(I) from thiosulfate leaching solution.

Experimental investigation for thermal performance of various heat sinks by alumina RT-70HC (NsPCM): Sustainable approach for thermal energy storage applications

This article explores the thermal management of three heat sinks with multiple topologies, such as the unfinned heat sink (US1), the square-finned heat sink (SS2) and the metallic porous foam-based heat sink (PFS3). The goal is to enhance their overall performance using smart nanomaterials to strengthen PCMs thermal conductivity with Al2O3/RT70HC, (NsPCM), under different transient heating loads (10–30 W) and varying nanomaterials saturation levels between 0.15 and 0.25 wt%. The results showed that the insertion of NsPCM lowered the bottom temperature of all heat sinks. The thermal performance of PFS3 was even better than US1 and SS2 at all Al2O3 saturation and heating loads, lowering the bottom temperature and achieving critical operational temperatures of 55 °C and 70 °C effectively. PFS3 has the highest surface area to volume ratio, exceptional thermal conductivity, and superior weight advantage compared to pin fin heat sinks. However, other highly conductive metallic foams instead of copper foam may be tested to avoid oxidation with alumina nanomaterials and enhance heat transfer. Therefore, adding nanomaterials into PCM is highly encouraged for sustainable advancement in electronic thermal management.

One-dimensional consolidation of highly saturated abandoned-soil under time-dependent stress: An analytical study

A thorough knowledge of the consolidation behavior of highly saturated soil under time-dependent stress is essential for the design and construction of abandoned-soil dump sites in the soft soil regions of China. In this study, one-dimensional consolidation analytical solutions are derived for such soil under one-way and two-way drainage conditions, accommodating the time-dependent stress created by various dumping protocols. Representative soil samples are obtained, and consolidation tests are conducted with various saturation degrees (one-way drainage) and loading protocols (two-way drainage), to verify the consolidation equation and determine its range of applicability to various saturation degrees. The effects of layer thickness, dumping type, and compaction degree on the consolidation behaviors of highly saturated abandoned-soil dumps are investigated. The one-dimensional consolidation equation is applicable to soil with saturation degree not lower than 75% under instantaneous stress, stepped stress, and linear stress. The pore pressure distribution with depth is not symmetrical; the eccentric distance of consolidation degree increases with increasing layer thickness in the stress application stage and is approximately zero in the stress keeping stage. The pore pressure at middle of the soil layer increases with increasing layer thickness and decreases with increasing dumping rate from the completion of soil dumping. With increasing compaction degree, the middle pore pressure increases, while the surface settlement decreases. In the premise of the stability of an abandoned-soil dump, where the goals are to reduce post-construction settlement and to shorten the consolidation process of the entire soil layer, the important factors are smaller layer thickness, higher dumping rate, and larger compaction degree.

Simple and environmentally friendly metal recovery from waste printed circuit boards by using deep eutectic solvents

Increased environmental awareness has necessitated the development of a simple and environmentally friendly method for metal recovery from waste printed circuit boards (WPCBs). Deep eutectic solvents (DESs) are environmentally friendly and non-aqueous lixiviants that can leach metal oxides to replace mineral acids. In this study, three choline chloride (ChCl)-based DESs were synthesized, using ethylene glycol, oxalic acid (OA), and glycolic acid (GA) as the hydrogen bond donors in the eutectic mixtures. The time-dependent leaching yields and saturated loading capacities of the DESs to typical metal oxides and Ag were evaluated. Considering the leaching performances, a simple and environmentally friendly method for metal recovery from WPCBs was established, based on two-stage DES leaching processes. The research object was the mixed metal powder collected from the mechanical processing of WPCBs. The results indicated that 90.35% of Zn, 87.47% of Pb, and 16.77% of Cu were removed from the mixed metal powder after calcination by leaching of the ChCl-GA DES and precipitation of the oxalic acid solution. When the residue was subjected to ChCl-OA DES leaching, Cu was recovered by diluting ChCl-OA DES with water. Specifically, 74.93% of Cu was separated in the form of CuC2O4·2H2O with a purity of >98 wt%. The Sn remaining in the aqueous solution was efficiently recovered by the addition of reduced Fe powder, and the recovery yield of Sn in the recovery product was 51.29%. Finally, the advantages of a simplified and environmentally friendly process framework, are highlighted by a comparison of the recovery strategy for WPCB proposed in this study with conventional pyro- and hydro-metallurgical approaches.

Adsorption mechanisms of ethane, ethene and ethyne on calcium exchanged LTA and FAU zeolites

The aim of this study is to unravel the influence of single, double and triple bonds in hydrocarbons on the mechanisms of adsorption on zeolites. Therefore, the adsorption of the C2 hydrocarbons ethane, ethene and ethyne on different adsorbents is studied by adsorption calorimetry. As adsorbents pure sodium LTA (NaA) and FAU (NaX) zeolites and calcium exchanged CaNaA and CaNaX zeolites are used. Based on experimental loadings and heat of adsorption, the influence of the number and distribution of cations on different cation positions are discussed in detail. With increasing degree of exchange the increasing number of Ca2+-cations introduce energetically more valuable adsorption sites into the zeolites. On the other hand, the decreasing total number of cations has a negative effect on saturation loading. The impact of these opposing effects and the different occupation of cation positions on the interactions and mechanisms occurring are discussed. The loading increases from ethane to ethene to ethyne and shows higher values on FAU compared to LTA. In terms of interactions, due to the single bond, in ethane only dispersion and induction interactions are formed. In ethene and ethyne due to the double and triple bonds, respectively, additional quadrupole cation and π-interactions occur. In this study, for the first time the formation of a π-complex with Ca2+-cations at position I in LTA and at positions II, III, and III’ in FAU is demonstrated. For ethyne, additional π-complex formation with Na+-cations on the identical positions is also detected, which was previously unknown in literature.