High Feed Concentration Research Articles

Catalytic enhancement of water gas shift reaction with Cu/ZnO/ZSM-5: Overcoming challenges of CO2 and H2 rich feeds

Water gas shift (WGS) reaction commonly converts CO to CO2 using H2O and produces H2 and CO2 in a catalytic fixed bed reactor. This study aims to develop a Cu/ZnO/ZSM-5 catalyst loaded in water gas shift reactor for converting typical synthesis gas produced from dry reforming of methane (DRM) at medium temperature shift (MTS, 200–350 oC) conditions and for preventing reverse reaction due to high feed concentrations of CO2 and H2. The Cu/ZnO/ZSM-5 catalyst was prepared by impregnation method with lower Cu metal loading of 5, 10, and 15 wt%, respectively, compared to commercial catalysts. The synthesized catalyst was characterized using XRF, XRD, SEM, H2-TPR, NH3-TPD, and TGA. The catalyst activity and stability for the WGS reaction were tested in the fixed bed reactor at atmospheric pressure and temperature of 325 °C. The experimental results show that CO conversion increases with increasing Cu loading. The 15 wt% Cu/ZnO/ZSM-5 catalyst showed the best results with a CO conversion of 35% and a yield of H2 of 36% and showed good stability for 32 h. Based on the TGA, the 15 wt% Cu/ZnO/ZSM-5 catalyst forms a 0.04 g carbon/g catalyst, which is much lower when compared to commercial catalyst (0.105 g carbon/g catalyst). The relative activity of the synthesized catalyst indicates 2.4 times better when compared to commercial catalysts. High concentrations of H2 and CO2 in the feed may initiate side reactions, including reverse WGS, methanation, and carbon formation, which will decrease H2 yield.

Simulation study on mitigating permeate flux decline with electroosmotic flux in dead-end ultrafiltration process

Piezoelectric membranes establish electrokinetic phenomena, including electroosmotic flow, to mitigate membrane fouling in the ultrafiltration process. This study employs numerical simulations to evaluate the role and impact of the electroosmotic flux effect on permeate flux decline and fouling mechanisms in the dead-end filtration process for silicon dioxide particles. This research demonstrates that electroosmotic flux significantly alleviates flux decline across varying values of surface zeta potential, membrane porosity, particle size and inlet concentration. Specifically, the electroosmotic flux effect is most pronounced in reducing flux decline when the surface zeta potential is higher and the membrane structure is more porous. This reduction in flux decline is attributed to the enhanced lift and drag forces generated by electroosmotic flux near the electrical double layer, which prevents rapid initial adhesion and subsequent fouling, such as internal blocking and cake layer formation. Additionally, the electroosmotic flux effect is most effective with smaller particle sizes and higher feed concentrations, helping to mitigate flux decline that would otherwise occur in the absence of electroosmotic flux. Compared to experimental and modelling investigations, the electroosmotic flux effect is shown to complement a reduction in permeate flux drop to facilitate the longevity of membranes in the ultrafiltration process.

High recovery design of reverse osmosis process with high permeate water quality and low wastewater discharge for ultra-pure water production

Ultra-pure water (UPW) for electronic industry is produced via many unit processes including reverse osmosis (RO), pretreatments, membrane degasifier, and ion exchange processes. Generally, 2-pass RO system is adopted in UPW production process to remove ionic and organic matters to meet water quality requirements of post-treatments. Since RO concentrate occupies most of wastewater discharged from UPW production process, high recovery design is beneficial to reduce wastewater discharge. According to the solution-diffusion model, permeate concentrations increase at higher feed concentrations, which may limit to increase RO recovery. Interestingly, the bench-scale 2-pass RO test using five commercial membrane modules revealed permeate concentrations were not affected by feed concentrations below a critical value (35 mg/L as NaCl in this work). This means the first-pass RO recovery can be increased without decreasing permeate water quality as far as second-pass RO feed concentrations are below the critical values. Various 2-pass UPW-RO system designs (250 mg/L as NaCl of feed concentration) were analyzed using an industrial RO system simulator to investigate the effect of the first- and second-pass recovery. The simulation works found that increasing the first- and second-pass recovery decreased wastewater discharge, energy consumption, and the number of membrane modules without degrading permeate water quality.

Development and performance investigation of a novel ultrasonic-assisted non-contact membrane distillation process to prevent membrane fouling

A novel non-contact membrane distillation (NCMD) process is proposed that prevents membrane fouling by preventing direct physical contact between the feed and membrane. The feed channel of the NCMD module is equipped with an ultrasonic transducer that provides high-frequency mechanical oscillations to the feed film, which forms a fine mist of droplets and water column. Experiments are conducted to determine the feed height required to maximize the evaporation rate, and the effects of feed temperature, flow rate, and ultrasonic power on the permeation flux. The results reveal that the highest permeation flux occurs at a feed height of 20 mm, and an increase in the feed height and flow rate decreases the ultrasonic cavitation effect, while a higher feed temperature and ultrasonic power significantly increases the permeation flux. At the feed temperature of 60 °C, feed flow rate of 1.0 L/min, and ultrasonic current of 600 mA, the permeation flux is 6.3 kg/m2h, which is 8.4 times greater than that of the NCMD process without ultrasonic treatment. The corresponding specific energy consumptions with and without the ultrasonication are 647 and 6028 kWh/m3, respectively. Moreover, the long-term experimental results indicate that the proposed system is unaffected by high feed concentrations.

Thermodynamic and economic comparisons of supercritical water oxidation and gasification of oily sludge under hydrothermal flames

Dual-shell reactors using hydrothermal flames as internal heat source were proposed for supercritical water gasification (SCWG) and oxidation (SCWO) of oily sludge to achieve fast preheating and avoid corrosion, salt plugging, and overheating. The SCWG and SCWO systems with hydrogen-rich syngas and electricity outputs, respectively, were established and simulated using Aspen Plus 11. Simulation models were validated by comparing with experimental products and temperature profiles. The maximum exergy destruction coefficients of 28.01% and 24.31% appear in the combustion reactor for both the SCWG and SCWO systems, respectively, indicating the indirect preheating method with hydrothermal flame is critical to the energy efficiency. The increase of reaction temperature promotes hydrogen but inhibits methane formation in the SCWG, and more steam but less syngas is output at higher reaction temperatures. Although more steam and electricity outputs are present at higher reaction temperatures for the SCWO, more fuel input is required. Lower exergy efficiencies are obtained at higher reaction temperatures in both the SCWG and SCWO systems for more energy is output as low grade steam. Less fuel input is required for both the SCWG and SCWO systems at higher feed concentrations, and higher exergy efficiencies can be obtained. The net treatment cost for the SCWG and SCWO systems are 119.19 and 215.47 USD/t, respectively, indicating the SCWG is more economically competitive compared with the SCWO.

High-flux ultrasonic processing for lithium separation using ionic liquid impregnated composite membranes

Battery industry, one of the most crucial components of the modern world, relies heavily on lithium production, and brines from the spent battery materials is one of the most important sources to exploit lithium. A new ultrasonic assisted membrane processing is proposed for lithium separation simulated brine. The effects of membrane composition, feed concentration, and ultrasonic conditions on the lithium extraction efficiency have been explored. The composite membrane including polysulfone (PSF) as the support and 1-alkyl-3-methylimidazolium hexafluorophosphate and tributyl phosphate as ionic liquid membrane. A porous PVC membrane has been used for prevention of the ILM loss. The optimal ultrasonic frequency is approximately 250 kHz, which matches the bulk modulus of the membrane and enhances the separation efficiency. Higher frequencies and optimized amplitude and pulse cycle settings further improve the lithium flux and selectivity. Moreover, higher flux and selectivity are achieved when separating lithium from alkali metal chlorides at higher feed concentrations, ranging from 250 ppm to 1000 ppm. The mechanism of enhanced lithium extraction by ultrasonics is attributed to the combination of microbubble formation, cavitation, and heat generation, which disrupt the concentration gradient and facilitate lithium transport across the membrane.

Surface polarity modulation enables high-performance polyamide membranes for separation of polar/non-polar organic solvent mixtures

Achieving highly selective separation of organic mixtures is crucial to modern fine chemicals and pharmaceutical industries. The membrane-based organic solvent reverse osmosis (OSRO) technology is expected to break through this barrier. The key to achieving the separation of organic mixed liquids is to design the OSRO membrane as needed based on the physical and chemical properties of the target separation solvent. However, this poses a huge challenge to traditional OSRO membranes. In this work, we report composite polyamide (PA) OSRO membranes with ultrahigh polar/non-polar organic mixture selectivity. The surface polarity of the composite PA membrane is increased by coating a layer of Fe3+/tannic acid (Fe3+/TA) layer on the surface of the PA membrane. The enhanced surface polarity increases the interaction difference between polar and non-polar solvents and the membrane. And a polarization layer is formed on the membrane surface, which weakens the concentration polarization effect on the membrane surface. Under high-concentration feed liquid (the mass ratio of methanol/hexane is 7:3), the separation factor of the prepared membrane reaches 218, which is the highest value of all OSRO membranes reported so far. For the first time, we establish a partial flux analysis for the OSRO process. This analysis unravels the pressure, concentration dependence, and sensitivity of separation performance. It provides novel insights into the design of high-performance OSRO membranes.

Experimental study and modeling of the liquid phase hydrogenation of acetylene

Selective hydrogenation of acetylene is an important process for both ethylene purification and ethylene production from acetylene in the industry. Herein, we proposed liquid phase acetylene hydrogenation for high feed concentrations of C2H2 (8 %) and CO (20 %), which is used to produce ethylene as a subsequent process of partial oxidation of natural gas. The experiments were carried out in a stirred tank reactor using N-methylpyrrolidone (NMP) as solvent and PdAg/SiO2 as catalyst. The liquid phase process obtained a much higher selectivity to ethylene (92 %) with only 8 % selectivity to green oil (GO) and C4, compared to 71 % ethylene selectivity in gas phase hydrogenation. Furthermore, in the liquid phase ethylene selectivity increased with increasing acetylene conversion, especially in the conversion range of 80–100 %. We developed a model incorporating reaction kinetics, mass transfer and reactor model to predict the acetylene conversion and ethylene selectivity in liquid phase hydrogenation. The calculation results indicated that hydrogenation in the liquid phase operated at a lower acetylene concentration and a higher H2/C2H2 ratio, especially under high acetylene conversions. This explains why the liquid phase hydrogenation of acetylene has a much higher selectivity to ethylene than the gas phase process.

A Study on the Treatment and Recovery of Sodium Sulfate (Na<sub>2</sub>SO<sub>4</sub>) Generated When Recovering Valuable Metals (Ni, Co, Mn, Li) from Waste Lithium Ion Batteries(LIBs)

Concerns have arisen regarding the high concentrations of sodium sulfate in wastewater resulting from the waste Li-ion battery wet recycling process. In addressing this issue, Bipolar electrodialysis was employed to desalinate high-concentration sodium sulfate and recover it as sulfuric acid and sodium hydroxide. The investigation encompassed various experimental variables, such as applied voltage (maintained at a constant level), feed solution concentration, the initial concentrations of sulfuric acid and sodium hydroxide, and volume ratio (F/A/B). Optimal conditions were determined by assessing water migration (%), the recovery rates (%) of sulfuric acid and sodium hydroxide, concentration of the recovered substances, process time, and energy consumption. A higher applied voltage was found to reduce process time while increasing energy consumption, with the 25 V condition considered preferable. When utilizing a high-concentration feed solution, energy consumption rises; however, it decreases per unit of processed solution, rendering a 1.30 M Na<sub>2</sub>SO<sub>4</sub> feed solution preferable. Increasing initial concentrations of sulfuric acid and sodium hydroxide substantially prolonged process time and increased energy consumption, emphasizing the advantage of commencing with low initial concentrations. Adjusting the volume ratio facilitated the concentration and recovery of sulfuric acid and sodium hydroxide with minimal impact on process time or energy consumption. Under the identified optimal conditions, the recovery of 1.70 M sulfuric acid and 2.44 M sodium hydroxide was achieved.

Enhancing microbial desalination cell performance through co-culture optimization and response surface methodology (RSM) in high saltwater feed concentration

In response to contemporary water and energy supply challenges, the Microbial Desalination Cell (MDC) emerged as an innovative solution, generating electricity and desalting saline water through wastewater treatment. However, the accumulation of ions during the desalination process adversely affects the biocatalyst performance, imposing scalability limitations on the technology. This study focused on enhancing the system's performance by co-culturing Shewanella oneidensis MR–1 and Escherichia coli. Through the response surface methodology, the effects of organic matter concentration and saltwater feed salinity were systematically investigated by central composite design. The study emphasizes the significant impact of studied factors on system performance. Elevated sodium lactate, sodium acetate concentrations, and salinity positively influence the desalination rate, with NaCl concentration showing an interaction effect with lactate. Positive linear relationships for OCV are observed with lactate and acetate. All factors significantly impact power output, with lactate having the most potent positive effect. Additionally, positive contributions to COD removal are noted for lactate and NaCl concentration and a positive interaction effect. These achievements facilitated the development of a mathematical model to optimize system performance by leveraging co-cultured inoculum and strategic environmental manipulation, overcoming limitations from ion accumulation, and opening the path for further advancements in this field.

Furfural to Cyclopentanone - a Search for Putative Oligomeric By-products.

We report here on the reductive rearrangement of biomass-derived furfural to cyclopentanone, a promising non-fossil feedstock for fuels and chemicals. An underreported aspect of this reaction is the inevitable formation of heavy byproducts. To mitigate its formation, process condition such as, solvent, catalyst, temperature, acidity, and feed concentration were varied to unravel the chemistry and improve the reaction performance. Water medium was confirmed to play a crucial role, as organic solvents were unable to deliver cyclopentanone or heavy by products. Copper-based catalyst showed the highest selectivity for ring-rearrangement, reaching 50 mol % under the conditions investigated. The main factor influencing the yields of cyclopentanone (CPO), and promote oligomer formation, are the feed concentration and the pH, as high feed concentrations and high acidity facilitate the self-polymerization of furfuryl alcohol (FALC). This was confirmed by dedicated experiments using FALC and the hydroxypentenone intermediate as feed. The concentration challenge could be mitigated by slowly dosing the feed, which increased the desired product yields by 4-12 mol %. Nevertheless, most oligomers appeared to fall in the range of common liquid fuels and could be converted to diesel by hydrodeoxygenation.

Alkaline pulping catalyzed ordered conversion of bark in supercritical water

The hydrophilicity of lignocellulosic biomass hinders the application of a high concentration slurry for supercritical water gasification, thereby reducing the gasification efficiency and energy self-sufficiency. A pretreatment method of alkaline pulping with KOH and NaOH was proposed to achieve the high feed concentration for continuous reactor and macromolecular simplification for barrier reduction of conversion. In this study, bark as an example of lignocellulosic biomass, whose 30 wt% and 40 wt% slurries with favorable rheology and stability, was prepared by alkaline pulping successfully. The minimum alkali consumption of NaOH and KOH pulping for 30 wt% and 40 wt% were 11%–14%, 16%–20%, and 16%–21%, 23%–28%, respectively. The most economical conditions were 180 °C and 24% KOH addition. All slurries prepared by NaOH and KOH at 180 and 200 °C could satisfy the industrial standard of coal-water slurry, and only 3–5 times higher than water viscosity. The bark macromolecules were restructured due to the hydrolysis of cellulose and lignin by breaking down the hydrogen bond and ether bond with trivial hydrocarbon matrix loss. The scattered crystal growth facilitated the uniform premixing of bark and water. Meanwhile, a surface particle charges potential increase leading to a heightened repulsive force by alkaline pulping furtherly enhanced the premixing effect. Additionally, metal ions could be deposited onto the bark surface during alkaline pulping. The chemical modification leading by alkaline pulping achieved the premixing of feedstock and water to form bark slurry. The conversion barrier was decreased to fulfill the ordered conversion, and 95.66% gasification efficiency for 40 wt% bark slurry was displayed at 600 °C with a preheated water of 6. Phenolic compounds and hydrocarbons were the most dominant components in liquid products. Polycyclic aromatic hydrocarbons in liquid products were detected at 620 °C with a preheated water of 4. The functional groups of organic matter in the slurry were significantly converted into the gas phase, and lattice oxygen was produced in the solid product. The alkali recovery was 65% at the optimal gasification condition, and achieved the maximum of 80% at 580 °C. The successful completion of this research affirms the dominance of the pulping-alkali recovery-gasification method for expanding the application of SCWG of lignocellulosic biomass in large engineering projects.

A novel in-situ hydrolysis approach to prepare ultra-selective and ultrasmooth nanofiltration membrane for efficient and sustainable ion separation

Nanofiltration (NF) membranes are increasingly recognized for their proficiency in monovalent/divalent ion separation, making them highly suitable for application such as water softening and resource recovery. This study introduces an innovative in-situ hydrolysis method to enhance the ion selectivity of thin-film composite nanofiltration (TFC-PA NF) membranes. In this method, the reactive monomer in the oil phase was pre-hydrolyzed by contacting with water, producing a partially hydrolyzed monomer that remained soluble in the oil phase. This in-situ hydrolysis process introduced more carboxylic groups to the membrane. That could lead to a proper enlargement of the pore size, subsequently facilitating the separation of Cl−/SO42−. Additionally, the hydrolysis altered the polarity of the acyl chloride molecule, prompting its accumulation at the oil/water interface and accelerating the polymerization reaction rate. This resulted in a thin and exceptionally smooth PA layer. The resulting membrane exhibited a remarkable Cl−/SO42−separation factor of ∼316 under moderate feed concentration and ∼478 under high feed concentration, while maintaining decent water permeance (14.4 L m−2 h−1 bar−1). Moreover, its maintained surface carboxylic group density, combined with ultra-low surface roughness, offered drastically enhanced fouling resistance. Our study illuminates the pathway for a straightforward and scalable method to fabricate highly selective membranes with superior fouling resistance.

Ultrasound assisted efficient separation of lithium from brine with a composite polyether sulfone-ionic liquid membrane.

Green, selective and efficient extraction of lithium as one of the most important components for energy storages with ultrasound-assisted membrane separation of lithium from brine, which contains alkali metal chlorides, is conducted using a composite membrane. The composite membrane is formed by sealing a supported ionic liquid membrane (consisting of 1-alkyl-3-methylimidazolium hexafluorophosphate ([RMIM][PF6]) + TBP) with a polyethersulfone (PES) membrane and a PVC thin film membrane. The aim of the study is to optimize the separation process for the selective extraction of lithium from alkali metals. Various parameters, including membrane composition, feed concentration, and ultrasonic conditions, are adjusted to identify the best operating conditions. The results reveal that a membrane containing xIL = 0.5 of [MOIM][PF6] exhibits higher selectivity compared to other membranes studied. The flux of lithium initially increases with shorter sonication times, but it decreases as the duration of ultrasonic irradiation is prolonged. The optimal frequency for the ultrasonic treatment, which matches the bulk modulus of the membrane, is approximately 250 kHz. Higher frequencies result in higher flux and selectivity in lithium separation; besides, optimizing the amplitude and pulse cycle of the ultrasound at 75% leads to increased flux. Moreover, higher flux and selectivity (percentage of lithium with respect to the all of the ion flux) are achieved when separating lithium from alkali metal chlorides at higher feed concentrations, ranging from 250 ppm to 1000 ppm. The selectivity is influenced by the hydrophobicity, which depends on the behavior of the ionic liquid membrane. The process is promising for the future of the lithium mining from brine.

Using machine learning techniques to predict ammonium concentration in membrane contactors for nitrogen recovery as a valuable resource

The availability of real-time measurements of primary quality water variables is one of the key challenges in the wastewater treatment industry. However, due to the cost and maintenance requirements of sensors and probes for on-line measurement of primary quality variables, the prediction of these variables via data-driven approaches using as inputs easy-to-measure process variables has attracted research interest. In this paper, different machine learning techniques: feed-forward artificial neural network, random forest, support vector machine, gaussian process regression and partial least squares were used to predict in real-time the total ammonium nitrogen concentration during the operation of a hollow fibre membrane contactor. This recently developed technology allows the recovery of nitrogen from nitrogen rich streams (i.e. supernatant of anaerobic digesters in wastewater treatment plants) as ammonium sulphate (a marketable fertilizer). These contactors are usually operated in batch mode, pumping the high nitrogen concentration feed from the storage tank, where the total ammonium nitrogen concentration decreases progressively as the fertilizer is produced. Knowing the real-time concentration of total ammonium nitrogen in the storage tank would enable the optimization of the process operation, avoiding its operation with conservative fixed-time batch duration. The pH is an easy-to-measure process variable usually available in wastewater treatment plants that was used as input of the tested data-driven models, together with two extracted features from this variable (its derivative and increments after each reagent dosing). The number of total ammonium nitrogen measurements in the collected database is 2350 data points (corresponding to 8 complete batches, which were divided into 6 for training the data-driven models and 2 for testing them), ranging from 987 to 2.5 mg NH4+-N/L which covers almost the complete range of total ammonium nitrogen concentration values in the membrane contactor. The predictive ability of the developed predictive models was evaluated on the test data set by four indices, namely: the root-mean-square error, the slope and the intercept of the linear fit between the measured and predicted concentrations and the determination coefficient. The results showed a strong predictive ability of the fitted ANN that outperformed the other approaches exhibiting a determination coefficient of 0.99 and the lowest root-mean-square error (19.87 mg/L) in the test set. Permutation variable importance demonstrated that all machine learning techniques depended mainly on the two variables extracted from the pH: its derivative and increments, which resulted to be more important than the pH itself to predict the total ammonium nitrogen concentration.

Monitoring Membrane Fouling Using Fluid Dynamic Gauging: Influence of Feed Characteristics and Operating Conditions.

Recent studies on membrane fouling have made considerable progress in reducing its adverse effects. However, a lack of comprehensive studies focusing on the underlying fouling mechanisms remains. This work aims to address a part of this gap by investigating the influence of feed suspension chemistry and operating conditions on the fouling characteristics of microcrystalline cellulose. Fluid dynamic gauging (FDG) was employed to monitor the properties of fouling layers under varied conditions. FDG results revealed that the cohesive strength of fouling layers increased in the direction towards the membrane, which can be associated with the higher compressive pressures exerted on foulants deposited near the surface. At lower pHs and higher ionic strengths, reduced electrostatic repulsions between particles likely resulted in particle agglomeration, leading to the formation of thicker cakes. In addition, thicker cake layers were also observed at higher feed concentrations, higher operating transmembrane pressures, and longer filtration times. The cross-flow velocity influenced the resilience of fouling layers significantly, resulting in thinner yet stronger cake layers in the transition and turbulent flow regimes. These findings regarding the influence of feed characteristics and operating conditions on the fouling behavior can be beneficial in developing effective antifouling strategies in membrane separation processes.

Techno-economic analysis of integrated bipolar membrane electrodialysis and batch reverse osmosis for water and chemical recovery from dairy wastewater

Bipolar membrane electrodialysis (BMED) for acid and base recovery and batch reverse osmosis (BRO) for water recovery are analyzed technically and economically as a dairy wastewater treatment solution. The proposed process layouts also aimed to utilize recovered water and chemical within same industrial plant. The hybridization of BMED with BRO process is used to reduce capital and operating cost of BMED unit and compared with the standalone BMED process. The analysis reveals that the hybridization of BRO-BMED system achieve 25.8% less unit cost and three times higher concentration of acid and base chemicals compare to standalone system. The comparison of system is done at optimum current density of BMED process and permeate flux of BRO process. Sensitivity analysis of permeate flux, current density and feed salinity is carried out. The higher feed concentration is desirable and reduces the cost in BMED process and same with current density but up to 409 and 255 A/m2 in hybrid and standalone system respectively. In hybrid system, the multi-response surface analysis observes that higher permeate flux in BRO reduces the BMED cost but increases the BRO cost and the minimum cost of 14 USD/kmol is achieved at 26 LMH permeate flux.

Ion migration characteristics during the bipolar membrane electrodialysis treatment of concentrated reverse osmosis brine

Bipolar membrane electrodialysis (BMED) plays a unique role in liquid phase mass transfer and acid-alkali preparation, so BMED wastewater treatment and reuse applications are attracting increasing attention. Herein, BMED was used to treat the concentrated brine (ROC) produced during reverse osmosis (RO), recover valuable resources and produc acid and alkali. The effects of voltage, feed concentration ratio (FCR), and flow velocity on ion flux during BMED were systematically surveyed, and unusual phenomena were thoroughly analyzed during ion transport. The results showed that the main driving force for ion transport was operating voltage, a critical parameter determining operating time. Concentration polarization and concentration gradient caused by a high feed concentration significantly affected ion electromigration stability, and ion hydration characteristics were nonnegligible factors determining ion transport speed. Flow velocity had no marked impact on the experimental outcomes. Furthermore, water transport occurred with salt ions during liquid-phase mass transfer. Under the optimal operating conditions (voltage 24 V, FCR 2:1, flow velocity 55 L/h), the BMED system showed excellent, continuous and stable operation, and efficient production of mixed acid (0.88 mol/L) and mixed alkali (0.72 mol/) was achieved. The BMED process cost was 10.537 yuan/kg NaOH; therefore, process applications of BMED are economically feasible.

Electrochemical recovery lithium from brine via taming surface wettability of regeneration spent batteries cathode materials

Lithium-ion batteries are ubiquitous as energy storage technology in mobile electronics and hybrid electric vehicles. There is a necessity to develop new lithium extraction technologies to meet growing demand and diversify the global lithium supply chain. Electrochemical recovery is a promising method of Li+ extraction that is highly lithium selective, environmentally friendly and economical. In this work, the hydrophilicity of ZnO-coated LiMn2O4 (derived from regenerated lithium-ion battery cathode materials, rLMO) is modulated to construct electrochemical systems for the recovery of lithium from brine. The effects of current density, potential, the concentration of simulated brine, and the concentration of recovery solution on lithium extraction from the simulated brine are investigated via the response surface methodology-central composites design. The structure and morphology of the materials during lithium extraction were studied using SEM, TEM, XRD and Raman, and the electrochemical lithium extraction performance was investigated by cyclic voltammetry, galvanostatic and constant voltage. rLMO with Li vacancies has the dual functions of selective lithium extraction and ZnO coating to adjust the interface hydrophilicity, which can effectively improve the electrochemical performance. The average electro-adsorption capacity of the ZnO-modulate rLMO was 13.12 mg/g/cycle over five cycles. In the high-concentration feed solution (240 mM), the maximum adsorption capacity was 41.06 mg/g.

Numerical Investigation of Recommended Operating Parameters Considering Movement of Polymetallic Nodule Particles during Hydraulic Lifting of Deep-Sea Mining Pipeline

Previously conducted studies have established that pipeline hydraulic transport systems are currently the most promising deep-sea mining systems, and the pipeline transport performance of polymetallic nodules is one of the technical priorities. In this paper, a coupled CFD–DEM approach is adopted to numerically calculate the solid–liquid two-phase flow of seawater with polymetallic nodules. Small-scale experiments were conducted to validate the coupled model. Particle dynamics analysis was carried out under different inlet flow rates, feed concentrations and nodule fragmentation levels. The simulation results show that different operating parameters have significant effects on the pipeline transportation process. With low inlet flow rate, high feed concentration, and high percentage of large particles, the particle distribution and motion characteristics show a trend that is not conducive to safe transport. A set of recommended operating parameters for hydraulic transport of polymetallic nodule pipelines was summarized.