Chemical Liquid Research Articles

Effects of Temperature and Carrier Gas on Phosphorus Transformation in Biosolids Biochar

Phosphorus (P) is an essential macronutrient for plants. The focus of this work is to recover P from biosolids and their derived biochar. The effect of three different pyrolysis temperatures (400 °C, 500 °C, and 600 °C) and two carrier gases (CO2 and N2) on P fractionation and the speciation of P on biochars produced from two biosolids were investigated. The Hedley chemical sequential extraction method and 31P liquid NMR were used for P characterization and quantification. Higher pyrolysis temperatures increased P fixation and decreased short-term P bioavailability. Carrier gas had also significant effects on P fractionation in the biochars. Biochar produced in a CO2 environment had slightly higher water-soluble P, NaHCO3-Pi, NaOH-Pi, and residual P than in biochar prepared in a N2 environment, while HCl-P showed the opposite trend. Additionally, the predominant molecular configuration of P was present in the inorganic form identified by 31P liquid NMR spectra, while organic P transformed into inorganic P with increasing pyrolysis temperature.

Healthcare waste management knowledge, attitudes and practices of laboratory workers at a regional hospital, Lesotho

Background: Safe management of healthcare waste (HW) safeguards laboratory biosafety and biosecurity. Knowledge and attitudes influence HW practices, presenting a need for evidence of the current status.Objective: This study assessed the knowledge, attitudes and practice of laboratory workers towards waste management at a regional hospital laboratory in Lesotho.Methods: The study was conducted from March 2023 to June 2023 using a mixed-methods descriptive case study design. The entire population (n = 30) of technical and non-technical laboratory workers and generated waste were sampled. A structured questionnaire and an observational checklist were used to collect data. Waste generation was assessed by weighing and measuring waste volumes. Data were analysed using descriptive statistics.Results: All respondents (26/26; 100%) can define HW and (3/3) laboratory assistants (100%) gave correct responses for three questions, namely: risk associated with HW, waste container colour-coding, and disposal requirements. Knowledge on waste management responsibilities ranged between 0% (0/4) for cleaners and 54.5% (6/11) among laboratory technicians. Attitudes were mainly positive, and practices conformed in part to standard operating procedures. Infectious solid waste comprised 77% of solid HW, while 63% of chemical liquid waste emanated from the full blood count area.Conclusion: Knowledge exists among workers and attitudes are predominantly positive; however, some unsafe practices continue, thus knowledge is not fully translated to safe practices. Regular training and measuring and recording of HW were recommended.What this study adds: The study contributes understanding of the status of HW knowledge, attitudes and management practices, highlighting the need for compliance monitoring.

Highly para-selective alkylation of toluene by methyl mercaptan over silylated ZSM-5 zeolite

Friedel-Crafts alkylation of toluene with methyl mercaptan has been investigated in the presence of H-ZSM-5 and SiO2/H-ZSM-5 catalysts. The silica layers have been built on H-ZSM-5 zeolite by chemical liquid deposition of tetraethyl orthosilicate. The passivation with silica of the external surface of H-ZSM-5 zeolite has been confirmed by FT-IR spectroscopy and mesitylene isomerization, used as a model reaction. All catalysts exhibited notable behavior in the alkylation of toluene to xylenes. Efficiencies higher than 98 % in alkylation for both toluene and methyl mercaptan were obtained at 375 °C. In terms of para-selectivity, outstanding performance was revealed by the silylated zeolites. Thus, over 12 % SiO2/H-ZSM-5, at 375 °C and WHSV = 9.4 gtoluene+CH3SH gcat-1h−1, the para-xylene selectivity was close to 100 %. The experimental apparent activation energy for the toluene alkylation with methyl mercaptan catalyzed by H-ZSM-5 was 80 kJ/mol.

A dehydration membrane reactor towards highly efficient LPG synthesis via CO2 hydrogenation

In recent years, CO2 hydrogenation has garnered increasing attention as a promising avenue towards the conversion of captured CO2 to valuable liquid chemicals, including CH3OH, CH3OCH3, and liquified petroleum gas (LPG). However, chemical conversion of CO2 has proven to be immensely challenging, resulting in low CO2 conversion (<35 %) and product yields (<15 %). H2O, unavoidably evolved during CO2 hydrogenation, imposes both thermodynamic and kinetic penalties on CO2 hydrogenation reactions via adsorption on catalyst active sites and promotion of undesirable reaction pathways. In this work, to greatly facilitate direct conversion of CO2 to LPG over a bifunctional Cu/Zn/Zr on Al2O3 (CZZA)/Pd-β-zeolite catalyst, a dehydration membrane reactor (MR) featuring a H2O-conducting Na+-gated nanochannel membrane was studied. Before the incorporation of the Na+-gated membrane, the CZZA/Pd-β-zeolite was unable to produce LPG at 280–310 °C and 14 bar, and the CO2 conversion was limited to < 35 %. In stark contrast, the MR exhibited CO2 conversion and LPG yield of 72.1 % and 51.7 %, respectively. The operating conditions of the MR were systematically investigated to determine the maximum achievable performance resulting in CO2 conversion and LPG yield as high as 90.2 % and 60.5 %, respectively. Furthermore, the LPG space–time yield (STY) at the optimized conditions was near that of the best-performing traditional reactors (TRs) in the literature but at 3 times and 8 times increased CO2 conversion and time factor (W/F), respectively. The MR in this work demonstrates the synergistic efficacy of combined H2O removal and CH3OH consumption towards highly efficient hydrogenation of CO2 for LPG production.

Overturning CO2 Hydrogenation Selectivity from CH4 to CO by Strong Ru-FeOx Interaction Arising from a Multilayer Epitaxial Structure.

The catalytic conversion of CO2 to CO through hydrogenation has emerged as a promising strategy for CO2 utilization, given that CO serves as a valuable C1 platform compound for synthesizing liquid fuels and chemicals. However, the predominant formation of CH4 via deep hydrogenation over Ru-based catalysts poses challenges in achieving selective CO production. High reaction temperatures often lead to catalyst deactivation and changes in selectivity due to dynamic metal evolution or agglomeration, even with a classic strong metal-support interaction. Herein, we have developed a FeOx/Ru/Rutile multilayer epitaxial structure by depositing a FeOx layer onto the epitaxially grown RuO2 nanolayers on the surface of rutile nanoparticles. This multilayer epitaxial structure transformed into a structure in which Ru nanoparticles were decorated with FeOx layers with ultrastable strong metal-support interaction (SMSI). Subsequently, the FeOx decoration on Ru nanoparticles effectively shifted the dominant product from CH4 to 95% CO during CO2 hydrogenation. Remarkably, this catalyst exhibits exceptional stability and can be operated stably at 550 °C for a long time without apparent deactivation. Compared with the dynamic changes observed in supported Ru nanoparticles, the interaction between Ru and FeOx maintains their electronic states at different reaction temperatures. Furthermore, this Ru-FeOx interaction inhibits H2 activation capability, CO adsorption, and subsequent hydrogenation of CO. The transformation strategy employed here, which utilizes initial multilayer epitaxial structures, can be applied to construct SMSI to enhance metal catalysts' catalytic performance.

Fed-Batch Strategy Achieves the Production of High Concentration Fermentable Sugar Solution and Cellulosic Ethanol from Pretreated Corn Stover and Corn Cob.

The bioconversion of lignocellulosic biomass, which are abundant and renewable resources, into liquid fuels and bulk chemicals is a promising solution to the current challenges of resource scarcity, energy crisis, and carbon emissions. Considering the separation of some end-products, it is necessary to firstly obtain a high concentration separated fermentable sugar solution, and then conduct fermentation. For this purpose, in this study, using acid catalyzed steam explosion pretreated corn stover (ACSE-CS) and corn cob residues (CCR) as cellulosic substrate, respectively, the batch feeding strategies and enzymatic hydrolysis conditions were investigated to achieve the efficient enzymatic hydrolysis at high solid loading. It was shown that the fermentable sugar solutions of 161.2 g/L and 205 g/L were obtained, respectively, by fed-batch enzymatic hydrolysis of ACSE-CS under 30% of final solid loading with 10 FPU/g DM of crude cellulase, and of CCR at 27% of final solid loading with 8 FPU/g DM of crude cellulase, which have the potential to be directly applied to the large-scale fermentation process without the need for concentration, and the conversion of glucan in ACSE-CS and CCR reached 80.9% and 87.6%, respectively, at 72 h of enzymatic hydrolysis. This study also applied the fed-batch simultaneous saccharification and co-fermentation process to effectively convert the two cellulosic substrates into ethanol, and the ethanol concentrations in fermentation broth reached 46.1 g/L and 72.8 g/L for ACSE-CS and CCR, respectively, at 144 h of fermentation. This study provides a valuable reference for the establishment of "sugar platform" based on lignocellulosic biomass and the production of cellulosic ethanol.

Hydrothermal liquefaction for producing liquid fuels and chemicals from biomass-derived platform compounds: a review

Hydrothermal liquefaction for producing liquid fuels and chemicals from biomass-derived platform compounds: a review

Electromagnetic wave absorbing behavior of nano-Fe1Co0.8Ni1@C single-layer core-shell and nano-Fe1Co0.8Ni1@SiO2 @C double-layer core-shell composite particles

To effectively explore the influence of nano core-shell structure on the absorption properties of Fe1Co0.8Ni1@X composite particles, three groups of Fe1Co0.8Ni1@C single-layer core-shell structures with varying C coating layer thicknesses and Fe1Co0.8Ni1@SiO2@C double-layer core-shell structure magnetic composite particles were prepared via chemical liquid phase deposition and high-temperature carbonization, and corresponding electromagnetic absorption properties were investigated. The study revealed that the prepared nano core-shell Fe1Co0.8Ni1@X composite particles exhibited a near-spherical shape with particle size of approximately 100 nanometers. The core of the FeCoNi alloy particles was FCC polycrystalline with C coating layer thicknesses ranging from 2 to 3 nm, 10–20 nm, to 30–50 nm, while Fe1Co0.8Ni1@SiO2@C composite particles with SiO2 coating layer thicknesses of 5–10 nm and C coating layer thicknesses of 2–3 nm. As the C coating layer thickness increased, the specific saturation magnetization intensity showed a decreasing trend while the coercivity exhibited an increasing trend, all composite particles presented soft magnetic properties. With the increase of the C coating layer thickness, the real and imaginary parts of the dielectric constant of composite particles continued to rise, while real part of the permeability showed minimal change and imaginary part of permeability exhibited significant variation. Polarization relaxation and electric conduction were observed as C layer thickness increased and magnetic loss primarily including eddy current loss and resonance loss. Additionally, the peak of the dielectric loss of the composite particles demonstrated a shift towards higher frequency with increasing C coating layer thickness, and the dielectric loss of the Fe1Co0.8Ni1@SiO2@C double-layer coating structure sample was lower than that of the Fe1Co0.8Ni1@C. The attenuation constant of Fe1Co0.8Ni1@C composite particles increased with C coating layer thickness and rising continuously with the electromagnetic wave frequency. The double-layer coating structure exhibited a lower attenuation constant than single-layer coating structure and FeCoNi alloy particles, which presented the best impedance matching. Compared with the Fe1Co0.8Ni1 alloy particles, the electromagnetic wave absorption performance of the Fe1Co0.8Ni1@C composite particles was enhanced in both high and low frequency bands, and with the increase of the C coating layer thickness the main absorption frequency band of the samples with the same thickness shifted towards lower frequency. Furthermore, the thickness of sample decreased from 1.5mm to 2.0 mm to 1–1.5 mm as the C coating layer thickness increased. Maximum reflection loss |RLmax| of 61.76 dB and effectively absorbed bandwidth of 4.64 GHz was obtained for Fe1Co0.8Ni1@C composite particle.

Electronic cigarettes and their impact on oral health - review

Nowadays, the popularity of e-cigarettes is growing rapidly. Manufacturers of e-cigarettes advertise them as a less harmful option than traditional cigarettes, suggesting that their use can help reduce nicotine dependence and reduce the risk of smoking-related diseases. However, studies indicate that inhaling the chemicals in liquids can carry serious health consequences, particularly concerning the oral cavity Many of these preparations contain substances about whose effects we do not yet know enough, which raises concerns among public health professionals. The aim of this study was to provide an overview of e-cigarettes, including their popularity, the origins of their development, the substances they contain and the impact they have on oral health, which is most at risk from the harmful effects of e-cigarettes.

Molecular Engineering of Poly(Ionic Liquid) for Direct and Continuous Production of Pure Formic Acid from Flue Gas.

Electrochemical CO2 reduction reaction (CO2RR) offers a promising approach to close the carbon cycle and reduce reliance on fossil fuels. However, traditional decoupled CO2RR processes involve energy-intensive CO2 capture, conversion, and product separation, which increases operational costs. Here, we report the development of a bismuth-poly(ionic liquid) (Bi-PIL) hybrid catalyst that exhibits exceptional electrocatalytic performance for CO2 conversion to formate. The Bi-PIL catalyst achieves over 90% Faradaic efficiency for formate over a wide potential range, even at low 15% v/v CO2 concentrations typical of industrial flue gas. The biphenyl in PIL backbone affords hydrophobicity while maintaining high ionic conductivity, effectively mitigating the flooding issues. The PIL layer plays a crucial role as a CO2 concentrator and co-catalyst that accelerates the CO2RR kinetics. Furthermore, we demonstrate the potential of Bi-PIL catalysts in a solid-state electrolyte (SSE) electrolyzer for the continuous and direct production of pure formic acid solutions from flue gas. Techno-economic analysis suggests that this integrated process can produce formic acid at a significantly reduced cost compared to the traditional decoupled approaches. This work presents a promising strategy to overcome the challenges associated with low-concentration CO2 utilization and streamline the production of valuable liquid fuels and chemicals from CO2.

Effect of external surface barriers over hierarchical ZSM-5 zeolite on n-heptane catalytic cracking

To better understand external surface barriers on hierarchical ZSM-5 zeolite, SiO2 layers were constructed over zeolite nanocrystal by using chemical liquid depositions (CLD). Diffusion measurement showed that the apparent diffusion rate over the zeolite was increased by up to 142 % after SiO2 deposition, indicating that the external surface barriers had been significantly reduced. The performance of hierarchical ZSM-5 zeolite for n-heptane catalytic cracking indicated that the catalytic activity (TOF) was increased from 0.55 to 0.91 s−1 after 3 nm layer of SiO2 deposition, leading to a total yield increase of ethylene and propylene by up to 23 %. The strong positive correlation of catalytic activity with apparent diffusion rate suggests that reducing external surface barriers can improve the utilization efficiency of active sites in micropores and enhance the catalytic activity of the zeolite. These results demonstrate that CLD of SiO2 can reduce external surface barriers on hierarchical zeolite, thereby improving its cracking performance.

LLDPE/TiO2 composites with high UV aging resistance and mechanical properties by controlling the alumina coating on TiO2

AbstractFor preparing high performance LLDPE film, the photocatalytic activity and the UV absorption capacity of TiO2 were regulated by the alumina coating content on the surface of TiO2. Alumina‐coated TiO2 was prepared by the chemical liquid deposition method, and characterized by element analysis, TGA, FTIR, and morphology observation. The alumina coating layer had been proven to covalently bind to the surface of TiO2 through AlOTi bonds, which formed a continuous and dense coating layer, followed by forming a loose flocculent coating layer with the increase of alumina content. The alumina coating layer could significantly reduce the formation of carbonyl group on the LLDPE chains, and enhance UV aging resistance of LLDPE by inhibiting the photocatalytic activity of TiO2. Moreover, the dispersion of alumina‐coated TiO2 in the LLDPE matrix was improved. Thus, the transmittance of LLDPE/alumina‐coated TiO2 composites was reduced and the whiteness was improved. Importantly, the continuous and dense alumina coating layer was enough to inhibit the photocatalysis effect of TiO2 on LLDPE. The further increase of alumina coating content reduced the UV absorption capacity of alumina‐coated TiO2 and its compatibility with the LLDPE matrix. Therefore, the best alumina coating content on the surface of TiO2 was 1.46 wt% for preparing high performance LLDPE/TiO2 composites.Highlights Alumina‐coated TiO2 with controllable coating thickness was successfully synthesized. LLDPE/alumina‐coated TiO2 has excellent UV aging resistance and mechanical properties. The photocatalytic activity and UV absorption capacity of TiO2 could be regulated. 1.46 wt% of alumina coating is the best content for high performance LLDPE/TiO2 composites.

Minitab 20 and Python based-the forecasting of demand and optimal inventory of liquid aluminum sulfate supplies

In a company, inventory management is crucial due to the significant impact on various aspects of the business. Similarly, the Indonesian water supply company (PDAM) requires effective inventory management to ensure the supply of liquid aluminum sulfate chemicals. The probabilistic statistical inventory control (SIC) model is commonly used for inventory management. However, previous research on chemical inventory models in PDAMs often relied on simple linear regression to forecast demand data, which fails to capture the inherent volatility in demand. Therefore, this research aimed to predict demand data using the seasonal autoregressive integrated moving average (SARIMA) method and determine the optimal policy for supplying liquid aluminum sulfate chemicals. The results showed that the best demand forecasting model was SARIMA (2,1,2) (1,1,0)12 with a mean absolute percentage error (MAPE) value of 8.19%. The finding of the optimal inventory policy showed a safety stock value of 11,922.35 kg, a reorder point value of 49,511.20 kg, and an order quantity of 21,526.59 kg, leading to a total cost of IDR 11,132,034,145.45. The sensitivity test also showed that variations in lead time, price, μ, and σ parameters directly influence changes in total cost, reorder point, and safety stock. These calculations were conducted using Minitab and Python software.

Non-thermal plasma-catalytic processes for CO2 conversion toward circular economy: fundamentals, current status, and future challenges.

Practical and energy-efficient carbon dioxide (CO2) conversion to value-added and fuel-graded products and transitioning from fossil fuels are promising ways to cope with climate change and to enable the circular economy. The carbon circular economy aims to capture, utilize, and minimize CO2 emissions as much as possible. To cope with the thermodynamic stability and highly endothermic nature of CO2 conversion via conventional thermochemical process, the potential application of non-thermal plasma (NTP) with the catalyst, i.e., the hybrid plasma catalysis process to achieve the synergistic effects, in most cases, seems to promise alternatives under non-equilibrium conditions. This review focuses on the NTP fundamentals and comparison with conventional technologies. A critical review has been conducted on the CO2 reduction with water (H2O), methane (CH4) reduction with CO2 to syngas (CO + H2), CO2 dissociation to carbon monoxide (CO), CO2 hydrogenation, CO2 conversion to organic acids, and one-step CO2-CH4 reforming to the liquid chemicals. Finally, future challenges are discussed comprehensively, indicating that plasma catalysis has immense investigative areas.

Structural elucidation of tramadol, its derivatives, and metabolites using chemical derivatization and liquid chromatography-high-resolution tandem mass spectrometry.

Tramadol (T) is a strong painkiller drug that belongs to the opioid analgesic group. Several accidental intoxication cases after oral administration of T have been reported in the past decade. Tramadol, its derivatives, and metabolites present information-limited mass spectra with one prominent peak representing the amine-containing residue; therefore, their structural determination based on both electron impact mass spectrometry (EI-MS) and ESI-MS/MS spectra could be misleading. A novel analytical method for the structural elucidation of tramadol, its four homologs, and its two main phase I metabolites (N-desmethyltramadol and O-desmethyltramadol) was developed using chemical modification and liquid chromatography-high-resolution tandem mass spectrometry (LC-HR-MS/MS) with Orbitrap technology. After chemical derivatization, each of the investigated T series exhibited informative mass spectra that enabled better exposition of their structures. The developed method was successfully implemented to explicitly identify the structures of tramadol and its N-desmethyltramadol metabolite in urine samples at low ng/mL levels. An efficient derivatization-aided strategy was developed for rapidly elucidating the structure of tramadol-like compounds. The method is intended to assist forensic chemists in better diagnosing T and its analogs and metabolites in clinical or forensic toxicology laboratories.

Evaluation of the Impact of Parylene C Deposition Method on the Functional Properties of Fabrics.

The article presents the results of research on the impact of the use of an original, innovative method of deposition of Parylene C on the functional properties of fabrics with various potential applications (e.g., thermal and chemical protective clothing, packaging, covers and others). Verification of the effects of the method used was based on interdisciplinary research taking into account the impact of coating fabrics on changes in their structure (micro-CT), surface properties (contact angle), barrier properties (water and chemical liquid wetting), electrostatic properties (charge decay), biophysical properties describing heat and mass transfer (by the Alambeta system and thermal imaging) and flammable properties. Four fabrics made of synthetic organic fibres (meta-aramid, para-aramid) and natural inorganic fibres (basalt) were selected for testing. Given the complex structure of textile substrates, the results confirmed that the two assumed thicknesses of the Parylene C coating were consistent with the actual measurements. The findings indicated that the coatings significantly reduced water and acid absorption in the fabrics compared to unmodified ones. Thermal insulation property tests revealed that coated fabrics exhibited higher thermal conductivity than unmodified fabrics. Additionally, the presence of Parylene C on aramid fabrics resulted in a modest increase in their ignition resistance.

Aerodynamically Levitated Droplets as Small-Scale Chemical Reactors and Liquid Microprinters.

A thin liquid film spread over the inner surface of a rapidly rotating vial creates an aerodynamic cushion on which one or multiple droplets of various liquids can levitate stably for days or even weeks. These levitating droplets can serve as wall-less ("airware") chemical reactors that can be merged without touching-by remote impulses-to initiate reactions or sequences of reactions at scales down to hundreds of nanomoles. Moreover, under external electric fields, the droplets can act as the world's smallest chemical printers, shedding regular trains of pL or even fL microdrops. In one modality, the levitating droplets operate as completely wireless aliquoting/titrating systems delivering pg quantities of reagents into the liquid in the rotating vial; in another modality, they print microdroplet arrays onto target surfaces. The "airware", levitated reactors are inexpensive to set up, remarkably stable to external disturbances and, for printing applications, require operating voltages much lower than in electrospray, electrowetting, or ink jet systems.

Aerodynamically Levitated Droplets as Small‐Scale Chemical Reactors and Liquid Microprinters

AbstractA thin liquid film spread over the inner surface of a rapidly rotating vial creates an aerodynamic cushion on which one or multiple droplets of various liquids can levitate stably for days or even weeks. These levitating droplets can serve as wall‐less (“airware”) chemical reactors that can be merged without touching—by remote impulses—to initiate reactions or sequences of reactions at scales down to hundreds of nanomoles. Moreover, under external electric fields, the droplets can act as the world's smallest chemical printers, shedding regular trains of pL or even fL microdrops. In one modality, the levitating droplets operate as completely wireless aliquoting/titrating systems delivering pg quantities of reagents into the liquid in the rotating vial; in another modality, they print microdroplet arrays onto target surfaces. The “airware”, levitated reactors are inexpensive to set up, remarkably stable to external disturbances and, for printing applications, require operating voltages much lower than in electrospray, electrowetting, or ink jet systems.

Selective Isotropic Dry Etching of SiO2 Using F/H-Based Pulsed Remote Plasma and a Vapor Phase Solvent

Isotropic etching generally employs liquid-based wet etching techniques. However, due to the high integration of devices, conformal etching is challenging in patterns with a high aspect ratio because liquid chemicals struggle to penetrate inside the pattern. Additionally, during the drying process after chemical treatment, pattern collapse is observed due to surface tension. Therefore, there is a need for dry isotropic etching techniques to replace wet etching techniques in next-generation device manufacturing processes.Typically, when high selectivity SiO2 isotropic dry etching is required, F-base/H-based gas mixtures are utilized to form HF, which serves as an etchant for SiO2. SiO2 can be dry etched through two different mechanisms. First, HF reacts directly with H2O or alcohol, etching SiO2. The other way is to produce (NH4)2SiF6 salt from the reaction of NH3, which can be formed in a plasma containing NH3 and NF3. This (NH4)2SiF6 salt is sublimated and removed by a following heating process at a temperature over 100ºC.The process above has some disadvantages, such as lowering the etch selectivity of SiO2 over Si and Si3N4 because Si and Si3N4 can be etched by F radicals remaining in the plasma. This study aimed to overcome these disadvantages by controlling the F radical through pulsing the remote plasma during the discharging of F-based/H-based gas mixtures for the formation of HF. By pulsing the remote plasma, SiO2 could be selectively etched at a higher etch rate relative to those of Si and Si3N4. Additionally, various types of H/F-based gas mixtures that do not contain nitrogen while producing HF were investigated to prevent the formation of ammonium powders, which can be a source of contamination in the chamber. Futhermore, the etching mechanisms were identified through gas phase anlysis and surface analysis. Also, any possible surface damage during the etching process was investigated.

Investigation of the impact of non-magnetic Si element addition and heat treatment on the electromagnetic wave absorption properties of medium entropy FeCoNiSi alloy particles

Based on chemical liquid phase reduction and high temperature annealing, the effects of non-magnetic Si element addition and heat treatment regime on the microstructure, magnetic properties, and electromagnetic wave absorption properties of medium entropy alloy particles FeCoNiSi were studied. The results show that the prepared Fe1Co0.8Ni1Six alloy particles have a spherical structure, and with the increase of Si content, the particle size continuously decreases, with the average particle size decreasing from 150 to 200 nm to 20-50 nm. After high temperature annealing, the alloy particles undergo some agglomeration and growth. The as-prepared Fe1Co0.8Ni1Six alloy particles exhibit an amorphous state, and crystallization occurs during high temperature annealing, but the increase in Si element content has a certain inhibitory effect on the crystallization of the alloy particles. With the increase of Si element content and annealing temperature, the specific saturation magnetization intensity of the material shows a decreasing trend, while the residual magnetism and coercivity show an increasing trend. With the increase of Si element content, the real and imaginary parts of the permeability change alternately in different frequency ranges. The magnetic loss mechanism for the three alloy particles was eddy current loss in the frequency ranges of 10-14GHz and 16.5-18GHz. With the increase of Si element content, the magnetic loss shows an increasing trend, and the impedance matching shows a decreasing trend. The Fe1Co0.8Ni1Si0.5 alloy particle sample has the maximum reflection loss |RLmax| of 28.2 dB at thickness of 2.3 mm, and the Fe1Co0.8Ni1Si0.7 alloy particle sample has an effective absorption bandwidth of 1.7GHz at thickness of 1.9 mm. Eddy current loss was the main magnetic loss mechanism for Fe1Co0.8Ni1Si0.6 alloy particles under 400 °C and 600 °C annealing conditions, and for Fe1Co0.8Ni1Si0.7 alloy particles under 600 °C annealing conditions. With the increase of annealing temperature, the fluctuation of dielectric loss with frequency decreases in the low frequency range, and increases in the high frequency range, while annealing reduces the fluctuation of magnetic loss with frequency. Under 400 °C annealing conditions, the attenuation constant of the three alloy particles was lower than that of the unannealed alloy particles, and under 600 °C annealing conditions, the attenuation constant of Fe1Co0.8Ni1Si0.5 alloy particles in the frequency range of 6-15GHz was higher than that of unannealed and 400 °C annealed alloy particles, and that of Fe1Co0.8Ni1Si0.6 alloy particles in the frequency range of 7-14GHz was higher than that of unannealed and 400 °C annealed alloy particles. High temperature annealing was not able to effectively improve the impedance matching performance of Fe1Co0.8Ni1Six alloy particles. The maximum reflection loss |RLmax| of Fe1Co0.8Ni1Si0.6 alloy particles under 600 °C annealing conditions was 37.8 dB.