Traditional Separation Approach Research Articles

Optimized purification methods for metallic contaminant removal from directly recycled Li-ion battery cathodes.

Metallic contaminants pose a significant challenge to the viability of directly recycling Li-ion batteries. To date, few strategies exist to selectively remove metallic impurities from mixtures of shredded end-of-life material (black mass; BM) without concurrently damaging the structure and electrochemical performance of the target active material. We herein present tailored methods to selectively ionize two major contaminants-Al and Cu-while retaining a representative cathode (LiNi0.33Mn0.33Co0.33O2; NMC-111) intact. This BM purification process is conducted at moderate temperatures in a KOH-based solution matrix. We rationally evaluate approaches to increase both the kinetic corrosion rate and the thermodynamic solubility of Al0 and Cu0, and evaluate the impact of these treatment conditions on the structure, chemistry, and electrochemical performance of NMC. Specifically, we explore the impacts of chloride-based salts, a strong chelating agent, elevated temperature, and sonication on the rate and extent of contaminant corrosion, while concurrently evaluating the effects on NMC. The reported BM purification process is then demonstrated on samples of "simulated BM" containing a practically relevant 1 wt% concentration of Al or Cu. Increasing the kinetic energy of the purifying solution matrix through elevated temperature and sonication accelerates the corrosion of metallic Al and Cu, such that ∼100% corrosion of 75μm Al and Cu particles is achieved within 2.5 hr. Further, we determine that effective mass transport of ionized species critically impacts the efficacy of Cu corrosion, and that saturated Cl- hinders rather than accelerates Cu corrosion by increasing solution viscosity and introducing competitive pathways for Cu surface passivation. The purification conditions do not induce bulk structural damage to NMC, and electrochemical capacity is maintained in half-cell format. Testing in full cells suggests that a limited quantity of residual surface species are present after treatment, which initially disrupt electrochemical behavior at the graphite anode but are subsequently consumed. Process demonstration on simulated BM suggests that contaminated samples-which prior to treatment show catastrophic electrochemical performance-can be recovered to pristine electrochemical capacity. The reported BM purification method offers a compelling and commercially viable solution to address contamination, particularly in the "fine" fraction of BM where contaminant sizes are on the same order of magnitude as NMC and where traditional separation approaches are unfeasible. Thus, this optimized BM purification technique offers a pathway towards viable direct recycling of BM feedstocks that would otherwise be unusable.

Postpartum Experiences of Early Skin-to-Skin Contact and the Traditional Separation Approach After a Very Preterm Birth: A Qualitative Study Among Mothers

Traditional care immediately after very preterm birth separates the mother and child by the transfer of the infant to the neonatal intensive care unit. A nonseparation approach is currently being considered, allowing early skin-to-skin contact in the delivery room/postoperative care unit. This study aimed to explore mothers’ experiences of early skin-to-skin contact and traditional care. A qualitative study using individual semi-structured interviews with five mothers from each of the two groups was conducted. Content analysis revealed that both groups’ experiences were characterized by (i) mothers’ need to be affirmed of their infants’ vitality, (ii) bonding challenges, and (iii) benefits of skin-to-skin contact. We suggest that early skin-to-skin contact after very preterm births is crucial for the bonding process and mothers’ feelings of safety and well-being. When early skin-to-skin contact is infeasible, our findings reveal the significance of photos, information, and the father’s presence at the time of postpartum separation.

Microfluidic Electrochemistry Meets Trapped Ion Mobility Spectrometry and High-Resolution Mass Spectrometry-In Situ Generation, Separation, and Detection of Isomeric Conjugates of Paracetamol and Ethoxyquin.

Over the last 3 decades, electrochemistry (EC) has been successfully applied in phase I and phase II metabolism simulation studies. The electrochemically generated phase I metabolite-like oxidation products can react with selected reagents to form phase II conjugates. During conjugate formation, the generation of isomeric compounds is possible. Such isomeric conjugates are often separated by high-performance liquid chromatography (HPLC). Here, we demonstrate a powerful approach that combines EC with ion mobility spectrometry to separate possible isomeric conjugates. In detail, we present the hyphenation of a microfluidic electrochemical chip with an integrated mixer coupled online to trapped ion mobility spectrometry (TIMS) and time-of-flight high-resolution mass spectrometry (ToF-HRMS), briefly chipEC-TIMS-ToF-HRMS. This novel method achieves results in several minutes, which is much faster than traditional separation approaches like HPLC, and was applied to the drug paracetamol and the controversial feed preservative ethoxyquin. The analytes were oxidized in situ in the electrochemical microfluidic chip under formation of reactive intermediates and mixed with different thiol-containing reagents to form conjugates. These were analyzed by TIMS-ToF-HRMS to identify possible isomers. It was observed that the oxidation products of both paracetamol and ethoxyquin form two isomeric conjugates, which are characterized by different ion mobilities, with each reagent. Therefore, using this hyphenated technique, it is possible to not only form reactive oxidation products and their conjugates in situ but also separate and detect these isomeric conjugates within only a few minutes.

A Branch-and-Price-and-Cut Algorithm for Resource-Constrained Pickup and Delivery Problems

We study a multicommodity, multiperiod, resource-constrained pickup-and-delivery problem inspired by the short-term planning of maintenance services at offshore wind farms. To begin a maintenance service, different types of relatively scarce servicemen need to be delivered (transported) to the service locations. We develop resource-exceeding route (RER) inequalities, which are inspired by knapsack cover inequalities, to model the scarcity of servicemen. In addition to a traditional separation approach, we present a column-dependent constraints approach so as to include the RER inequalities in the mathematical formulation. An alternative pricing strategy is developed to correctly include the column-dependent constraints. The resulting approach is broadly applicable to any routing problem that involves a set of scarce resources. We present a branch-and-price-and-cut algorithm to compare both approaches that include RER inequalities. The branch-and-price-and-cut algorithm relies on efficiently solving a new variant of the elementary resource-constrained shortest-path problem, using a tailored pulse algorithm developed specifically to solve it. Computational experiments show that the RER inequalities significantly tighten the root node relaxations. The column-dependent constraints approach then searches the branch-and-bound tree more effectively and appears to be competitive with the traditional separation procedure. Both approaches are able to solve instances of up to 92 nodes over 21 periods to optimality.

Anionic structural effect in liquid–liquid separation of phenol from model oil by choline carboxylate ionic liquids

Phenolic compounds exist in crude oil as pollutants, and their removal is vital important for the refining and further application of oils. In traditional separation approaches, strong acid and strong base have to be used to remove these compounds, which may cause serious environmental problems. In this work, 19 kinds of cholinium ionic liquids have been developed to separate phenol from model oil by liquid–liquid extraction. Structural effect of anions of the ionic liquids in the separation is systematically investigated. It is found that depending on the chemical structure of ionic liquids, phenol can be removed from toluene with single-step removal efficiency from 86 to 99% under optimal conditions. The type of substituent groups and the -CH2 number between two carboxylates have obvious effect on the removal efficiency, and more hydrophilic ionic liquids have a stronger extraction performance for phenol. Furthermore, thermodynamic, 13C NMR, 1H NMR and density functional theory calculations have been performed to characterize the extraction process and to understand the extraction mechanism. It is shown that the extraction of phenol from oil to ionic liquid is a favorable process, and this process is mainly driven by enthalpy change. The formation of the hydrogen bond between anion of the ionic liquid and -OH of phenol is the main driving force for the extraction of phenol from oil to the ionic liquids.

Simultaneously tuning dense skin and porous substrate of asymmetric hollow fiber membranes for efficient purification of aggressive natural gas

Highly permeable, selective, and stable asymmetric membranes are required to replace the traditional separation approaches for natural gas purification with higher energy efficiency and smaller footprints. Herein, we report on the design and engineering of defect‐free asymmetric hollow fiber membranes with a thin dense skin and highly porous substrate to effectively deal with aggressive natural gas. A crosslinkable polymer with rigid molecular structure and high molecular weight was synthesized for developing spinning dope with desirable solution properties. Phase separation behavior of the polymer was carefully controlled by systematic formulation of the dope composition and optimizing spinning conditions, thereby realizing simultaneously tuning dense skins and porous substrates of the spun asymmetric hollow fiber membranes. The crosslinked hollow fiber membrane, with well‐preserved delicate asymmetric nanostructures, exhibited unprecedentedly high and stable separation performance for long‐term processing extremely aggressive CO2/CH4 mixtures (with pressure up to 820 psi containing C6+ hydrocarbons), thereby showing great potential for practical application of natural gas purification. This work offers a new platform to create hollow fiber membranes with both high permeance and plasticization resistance in natural gas service. © 2019 American Institute of Chemical Engineers AIChE J, 65: 1269–1280, 2019

A New Assessment of Hydrological Change in the Source Region of the Yellow River

Hydrological responses to climate change are a widely concerning question, particularly for the source region of the Yellow River (SRYR), which is sensitive to climate change and is widely underlain by frozen ground. In considering climate change impacts on catchment properties, the traditional separation approach based on the Budyko framework was modified to identify and quantify the climatic causes of discharge changes. On the basis of the decomposition method, the traditional separation method and the modified separation method were used to analyse the discharge change in the SRYR. Using the observed annual maximum frozen depth (MFD) to indicate the frozen ground level, the impacts of frozen-ground degradation on the discharge change were further considered using the modified separation method. Our results show that the traditional separation approach underestimated climate-induced discharge change; over the past half-century, the discharge change in the SRYR has been primarily controlled by climate change. Increasing air temperature is generally a negative force on discharge generation; however, it also causes frozen ground to degrade—a positive factor for discharge generation. Such conflicting effects enhance the uncertainty in assessments of hydrological responses to climate change in the sub-basins with widely distributed permafrost.

Linear Quadratic Integrated Versus Separated Autopilot-Guidance Design

Two types of guidance and control design concepts are explored: a traditional separated approach and an integrated one. Using the integrated approach, two different guidance systems are presented: a single-loop guidance law and a two-loop autopilot-guidance law. In the two-loop case, the autopilot loop is designed separately from the guidance one, but all the states are fed back into the guidance loop. It is proven that the integrated guidance laws achieve the same performance for single-input single-output systems. The performance of the three guidance laws is evaluated and compared via a thrust vector control missile. It is shown that the performance of the separated guidance law is inferior to that of the integrated laws.

Iterative Decoding of Serially Concatenated Arithmetic and Channel Codes With JPEG 2000 Applications

In this paper, an innovative joint-source channel coding scheme is presented. The proposed approach enables iterative soft decoding of arithmetic codes by means of a soft-in soft- out decoder based on suboptimal search and pruning of a binary tree. An error-resilient arithmetic coder with a forbidden symbol is used in order to improve the performance of the joint source/channel scheme. The performance in the case of transmission across the AWGN channel is evaluated in terms of word error probability and compared to a traditional separated approach. The interleaver gain, the convergence property of the system, and the optimal source/channel rate allocation are investigated. Finally, the practical relevance of the proposed joint decoding approach is demonstrated within the JPEG 2000 coding standard. In particular, an iterative channel and JPEG 2000 decoder is designed and tested in the case of image transmission across the AWGN channel.

Coupled analysis of floater motion and mooring dynamics for a turret-moored ship

Traditional global response analyses of moored floating structures are calculated in two separated steps: calculations of floater motions; and dynamic response analysis of moorings and risers using the top end motions estimated in the first step. Typical shortcomings in the traditional separated approach are neglection or simplification of current forces and low frequency damping contribution from moorings and risers. In a coupled analysis procedure where floater motions and mooring and riser dynamics are calculated simultaneously, these drawbacks are avoided. Motions and mooring line tensions from model tests and simulations using coupled and separated analysis procedures are compared. Illustrations are given by extensive case studies of a turret-moored ship operating in 150 m, 330 m and 2000 m water depth. The main conclusions are that the traditional separated approach may be severely inaccurate, especially for floating structures operating in deep waters. Coupled analysis should be applied for deep water concepts, at least as a check of important design cases. The agreement between model test results and results from coupled analysis is very good.