Chemical Engineering Journal Advances最新文献

A catalytic system containing a copper-Schiff base complex in ethyl methyl imidazolium hexafluoro phosphate [(EMIM)PF₆] ionic liquid, where the ionic liquid was used as a solvent, was found to be very effective to catalyze the synthesis of benzazoles [i.e. imidazoles (C–N), thiazoles (C–S) and oxazoles (C–O)]. Substituted amines and alcohols reacted with each other in the given reaction conditions to give benzazoles. The reaction proceeded via a hydrogen transfer mechanism, which was proved by conducting series of reactions involving the conversion of aldehydes/ketones to corresponding primary and secondary alcohols. The reaction conditions were optimized with respect to catalyst concentration, best choice of the solvent, effect of different bases and the optimized chosen ones. It was found that the reaction required as low as 0.1 mol% of the catalyst and potassium carbonate as the base. Most interestingly the quantity of the products yielded the same when an equal ration of water: [EMIM]PF₆ mixture was used as the solvent, same as when the ionic liquid alone was used as the solvent. A wide range of substituted alcohols and amines were tested and the products were formed within a short reaction time and comparatively good yields.

The utilization of solid waste as a resource is a beneficial approach to achieve pollution reduction and carbon reduction simultaneously. In this paper, we developed a quaternary solid waste-based cementitious materials (SWCMs) that can be used as a substitute for cement by utilizing four types of solid waste, namely ground granulated blast furnace slag (GGBS), steel slag (SS), ammonia-soda residue (ASR) and desulfurization gypsum (DG). The performance optimization and carbon emissions of SWCMs are investigated by response surface methodology and emission factor calculations. The results showed that a second-order polynomial model can accurately predict the compressive strength of mortar specimens of SWCMs, with prediction accuracies of 96.78 % and 87.17 % for compressive strengths at 3 days and 28 days, respectively. In terms of raw materials, DG content positively correlates with the compressive strength of the mortar containing SWCMs, moreover, ratios of GGBS to ASR of less than two or more than eight are beneficial. In addition, the production process of each ton of SWCMs emits 71.51 kg CO₂, which is only 10 % of the production process of ordinary Portland cement. Overall, this work elucidates the influence of raw materials on the mechanical properties of quaternary SWCMs and quantifies their carbon reduction effects as a substitute for traditional cement, advancing the investigation and application of SWCMs in the realm of low-carbon materials.

Carbon dots (CDs) are nanostructures containing mainly carbon atoms and abundant functional groups. With remarkable and adjustable physicochemical properties, CDs have excellent hydrophilicity, photoluminescence (PL), biocompatibility, and low toxicity. Although the numerous advantages make CDs a research target for synthesizing advanced materials, some limitations are pertinent and must be corrected. Rare earth elements (RE) are excellent candidates for doping CDs, obtaining hybrid materials called RE-CDs to optimize luminescence properties, applicability, and quantum yields. Hybrids allow the combination of the advantageous characteristics of both CDs and RE, drastically improving their luminous and magneto-optical imaging performance and opening the door to numerous practical and technological applications. To date, no studies in the literature have provided in-depth analyses of the methods used to prepare RE-CDs, the characterization techniques used, the challenges, and a critical analysis of what could be improved in the synthesis by proposing practical solutions. To fill this gap, this review initially presents a detailed survey of CDs and RE separately. Subsequently, RE-CDs hybrid materials are addressed, as well as their obtainment, commonly used characterizations, and recent applications, from analyte detection to their functionality in medical nanodevices. Finally, criticisms and suggestions for future work are also discussed to inspire new research and discoveries about the technological potential of hybrid materials derived from the doping of RE-CDs.

The interest in recycling spent lithium-ion batteries (Li-ionB) has surged due to the rising demand for valuable metals (e.g., Co, Ni, Li and Mn) and concerns about environmental repercussions emanating from conventional battery waste disposal. Conventional precipitation-based hydrometallurgy recycling processes utilise Na-based or metal-based precipitants. The Na, from Na-based precipitants, is present in high concentrations in the process effluent since they are not recovered during the recycling process. The Na-rich effluent cannot be discarded since it doesn't meet environmental regulations as per the U.S. Environmental Protection Agency (EPA) (2023) therefore creating a storage and disposal problem. It is therefore imperative to utilise non-Na-based precipitants to eliminate the effluent disposal problem. This paper focuses on the recovery of Ni_xCo_yMn_z(OH)₂ and Li₂CO₃, main precursors for Li-ionB cathode production, from a typical spent Li-ionB cathode (NMC 532) using non-Na precipitant-based chemical precipitation. This study reports Ni_xCo_yMn_z(OH)₂ and Li₂CO₃ recovery from spent Li-ionBs for closed-loop Li-ionB cathode recycling through an integrated hydrometallurgy and chemical precipitation process. Through the utilisation of leachate solutions comprising 2 M H₂SO₄ + 6 vol.% H₂O₂, and a 75 g/L S/L ratio and conducting leaching for 120 min at a temperature of 60 °C and IS of 350 rpm, the recovery efficiency of 98.1 % for Li, 97.1 % for Co, 96.1 % for Ni, and 95.7 % for Mn. The pH of the NMC leachate was initially adjusted to 5 to precipitate Fe, Al and Cu impurities. Thereafter, active metal species (Ni, Mn and Co) were precipitated at a pH of 13 as Ni_0.5Co_0.2Mn_0.3(OH)₂ composite microparticles by adding LiOH precipitant. Thereafter, the Li-rich resultant liquor was further used to recover the Li by adding 3.4 mol of CO₂ bubbled at 0.068 mol (CO₂)/L.min and 40 °C for 45 min. The Li₂CO₃ precipitates were separated from the suspension through filtration followed by washing using deionised water and hot air drying. The reaction time is 45 mins, and the agitation speed is 150 rpm. Through this multi-stage precipitation process, >98 % of Ni, Co, Mn and > 91 % of Li can be recovered in the form of Ni_0.5Mn_0.3Co_0.2OH₂ and Li₂CO₃ respectively. The process exhibits great potential for recovery of valuable materials from spent Li-ionBs. The recovered Ni_0.5Co_0.2Mn_0.3(OH)₂ and Li₂CO₃ materials will be used as precursors in the anhydrous NMC cathode production process.

Many MgO sorbents exhibit high CO₂ uptake in the presence of high concentration CO₂ and aided by high space velocity, which unfortunately leads to low CO₂ capture efficiency from the gas stream. This study investigates the effect of Li/Na/K ratio on sorption performance in dilute CO₂ streams (15% CO₂) using alkali metal nitrates-promoted MgO sorbents at a low space velocity of 20 ml/g·min in fixed bed reactor. Study shows that the ratio of Li/Na/K in ternary alkali nitrate salt mixture significantly affects the induction periods for the second phase CO₂ sorption, which is a key contributor to high CO₂ uptake. High LiNO₃ content in ternary mixture leads to long induction period, and therefore lower CO₂ capacity during the 4 h period. Conversely, high ratios of NaNO₃ and KNO₃ leads to shorter induction periods. Among the samples, MgO with 9 mol% (Li_0.18Na_0.52K_0.3) exhibits the highest CO₂ sorption capacity of 5.56 mmol/g at 240°C in 4 h (20.6% CO₂ capture efficiency) and 3.18 mmol/g after 5 cycles (10.8% CO₂ capture efficiency). Comparative studies show that optimal temperatures for CO₂ sorption are higher when using pure CO₂ (280 to 320°C) than when using 15% CO₂ (240°C) due to the thermodynamic equilibrium. CO₂-TPD results indicate that CO₂ desorption proceeds in two phases similar to CO₂ sorption, and the presence of alkali salt in MgO also promotes the decomposition of bulk carbonate to CO₂. It is shown that molten salt migration and agglomeration of MgO particles are likely the factors that lead to decline in CO₂ uptake over the sorption-desorption cycles.

The current study describes composite membranes that utilise exfoliated graphitic carbon nitride (Eg-C₃N₄) as a promising membrane additive for oily-water separation, owing to its hydrophilic nature and high functionality. The integrated membranes have been discovered to have outstanding properties when Eg-C₃N₄ is used as a composite material in polysulphone (PSf) membranes. The study provides provide insights into the usage of such nanosheets to achieve good chemical interaction with the membrane matrix, enabling both Eg-C₃N₄ and PSf synergistic characteristics. The well-planned exfoliated g-C₃N₄-PSf composite demonstrated promising oil-water separation with an oil rejection capacity of >99 %. Furthermore, these exfoliated laminar planes interacted well with the polymer, resulting in membranes that were both thermally and mechanically stable. The membrane also has a high porosity range of 46.13 % to 76.03 % and a high-water uptake range of 42.23 + 1.68 % to 71.34 + 1.24 %, which explains the membrane's enhanced hydrophilicity and appropriate oily-water treatment capacity. Furthermore, the addition of Eg-C₃N₄ lowers surface roughness, which explains for the great antifouling capacity exhibited by the composite membrane, demonstrating a remarkable flux recovery ratio of about 99.1 % with no compromise in oil rejection during subsequent cycles.

The interest in recycling spent lithium-ion batteries (Li-ionB) has surged due to the rising demand for valuable metals (e.g., Co, Ni, Li and Mn) and concerns about environmental repercussions emanating from conventional battery waste disposal. This research is centered on the recovery of Ni and Co from synthetic Ni, Co, Mn and Li sulphate solutions mimicking the NMC 532 ratio of elements using a hydro-electrometallurgy process route that integrates hydrometallurgy and potentiostatic electrometallurgy techniques. This quasi-model is done to elucidate the effect of multiple influencing parameters, through isolation and varying, on the selective electrodeposition of Co-Ni from multi-ion (Li, Ni, Mn and Co) complex solutions before applying it using real cathode leachates. The selective electrowinning metal recovery process route is a cost-effective alternative to the energy, cost and material-intensive hydrometallurgy intermediate purification processes such as solvent extraction, selective precipitation, and ion-exchange. The study delves into the effects of various electrowinning parameters, including applied potential, temperature, pH, Co, Ni, Na₂SO₄, NaH₂PO₄ buffer concentration, and cathode rotational speed. These parameters were thoroughly investigated and effectively optimised to achieve the recovery of 97.2% pure Ni_0.65Co_0.35 at a rate of 0.060 g/cm².h with an impressive 89.25 % current efficiency. The composition of the electrowon deposit was meticulously quantified using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and subjected to analysis through a Scanning Electron Microscope (SEM-EDS). Additionally, the phase composition was evaluated using X-Ray Diffraction analysis (XRD). The results successfully demonstrate the technical feasibility of recovering Ni-Co composites, yielding high quantities of industrial-grade pure Ni-Co composites. This comprehensive electro-hydrometallurgical process, designed for both closed and loop recycling purposes, promotes a more environmentally preservative approach to recycling spent lithium-ion battery cathode material. The approach contributes significantly to the development of sustainable resource management infrastructure.

Metal-organic frameworks (MOFs) have gained tremendous attention based on the prospect of application-oriented structural tuning. In this study, the surfactant (SDS)-directed hydrothermal synthesis route was adopted for a one-pot, bottom-up synthesis of ZIF-8 spherical assemblies, stacked with externally oriented and intergrown two-dimensional (2D) nanosheets. The as-obtained nanosheet assemblies exhibited good crystallinity, a large surface area, and excellent thermal stability, as shown by XRD, BET, and TGA, respectively. More importantly, the ZIF-8 nanosheet assemblies displayed excellent small molecule adsorption characteristics, especially for the negatively charged dyes, including rose bengal (RB), uni-blue A (UA), and methyl orange (MO). Furthermore, samples showed a pseudo-second-order adsorption mechanism for dye molecules and presented a good fit for Langmuir's and Temkin's adsorption isotherms with an R² value of 0.98 and 0.94, respectively. Adsorbent–adsorbate electrostatic interaction, nanosheet structures, molecular size and structural aromaticity of the dye, and the presence of SDS functionalities were found as the essential components for the high-capacity dye adsorption as compared with previous studies.

To enable the widespread adoption of residential energy storage, sustainable, low-cost, long-life, and energy-dense battery technologies are required. Sodium-ion offers many of these characteristics, however often the system is tailored for energy rather than cycle life. In this work, the effect of synthesis conditions upon the primary and agglomerated secondary particle size and shape of the sodium-ion cathode material NaNi_1/3Fe_1/3Mn_1/3O₂ was investigated for optimization of energy and cycle life. A two-level full factorial experimental design was utilized to examine how the synthesis parameters (pH, molar ratio of ammonia/metal precursor salt, and stirring speed) affect the physical and electrochemical properties. This approach enabled a comprehensive investigation of the main effects and interactions of these parameters. The data from multiple synthesis runs were analyzed using statistical methods and regression analysis. This experimental design provided valuable insights into the relationship between synthesis parameters and material properties. Statistical analysis indicates that both physical and electrochemical properties are mainly controlled through pH and NH₄OH, while the effects of stirring speed are less pronounced. The optimal synthetic conditions producing the highest cycling performance were extrapolated from the statistical analysis. A validation experiment showed that particles synthesized with optimum parameters displayed a threefold increase in cycling performance together with uniformly distributed particle size and a high tap density.

Magnesium (Mg) in drinking water is essential for human health, with low concentrations in drinking water being reported to be correlated with poor cardiovascular health outcomes. Based on the literature and suggestions that the World Health Organization would soon announce guidelines for Mg content of drinking water, the Saline Water Conversion Corporation (SWCC) announced specifications in October 2020 targeting 15–25 ppm of Mg in product water. SWCC produces approximately 6 million m³ of potable water daily for domestic and industrial use in the Kingdom of Saudi Arabia, so meeting this Mg target will require the allocation of significant resources. In this report the different approaches to adding Mg in post-treatment of the product water from the SWCC's network of desalination plants are reviewed in order to optimise the additional capital investment and ongoing operational expenses. The most cost-effective option is to mix produced water with groundwater containing Mg, but where this is not feasible the next most cost-effective method for achieving a 15 ppm target was assessed to be treating desalination brine with nanofiltration (NF) to generate a magnesium-rich brine fraction that can be mixed with produced water. A one-stage NF process can meet the 15 ppm Mg target only with levels of chloride and total dissolved solids exceeding regulatory maximums in the produced water, so a multi-stage NF process with intermediate dilution was designed. While this has a significantly higher capital expenditure and energy requirement than one-stage NF, at the cost of energy in the Kingdom of Saudi Arabia it is still significantly less expensive than alternative approaches (0.009 USD/m³). This solution was implemented at an SWCC desalination plant on the Red Sea and has been delivering Mg-enriched water (∼15 ppm) to approximately 1.3 million people since May 2022 at an estimated additional operational cost of 0.007 USD per m³. For lower target levels of Mg supplementation (∼5 ppm), replacement of limestone with dolomite in post-treatment limestone contactors has been found to be a cost-effective process in plant-scale trials at another SWCC plant on the Red Sea.