Liquid-phase Reduction Research Articles

CO2 reduction by borohydride over modified biochar-loaded nickel-copper alloy at ambient temperature and atmospheric pressure

CO2 reduction with sodium borohydride (NaBH4) at ambient temperature and atmospheric pressure is considered as a low-energy technology that contributes to carbon neutrality. However, the hydrolysis of NaBH4 as the hydrogen donor leads to a decrease in formate production from CO2 reduction. In order to address this issue, nickel-copper bimetallic alloy supported on biochar modified with sodium hydroxide (NC/BS) was prepared by a modified liquid-phase reduction method as a cost-effective catalyst to enhance CO2 reduction for the first time. The nickel-copper loading and the molar ratio of copper to nickel of NC/BS were optimized to 10 wt% and 2:3, respectively. The NC/BS with 10 wt% nickel-copper loading (10 % NC/BS) was characterized by TEM, EDS mapping, XRD, XPS, FTIR, ICP and EA, and the results showed that nickel-copper nanoparticles were uniformly distributed on the catalyst surface and that -OH groups were present on the 10 % NC/BS. The optimal experimental conditions for the catalytic reduction of CO2 were determined to be that the 10 % NC/BS dosage was 20 mg, NaBH4 concentration was 100 mmol/L, and reaction temperature was 20°C. By using 10 % NC/BS, the formate production from CO2 reduction was increased by 42 % and the hydrogen production from NaBH4 hydrolysis was decreased by 29 %. The use of 10 % NC/BS improved the effective utilization of borohydride for CO2 reduction from 29 % to 50 %. Based on density functional theory (DFT) calculations, it was demonstrated that the alkali metals and -OH groups of 10 % NC/BS had strong adsorption capacity for CO2, which favored the activation of CO2 and lowered the thermodynamic barrier of CO2 reduction. In addition, the presence of nickel-copper bimetallic alloy was conducive to improving the reactivity of NaBH4, which could also promote the conversion of CO2 to formate.

Multi-scale heterogeneous composite elastomer absorbers synergistically enhanced by CoNi nanospheres and carbon nanotubes

The advancement of high-performance absorbers is essential for applications in electromagnetic wave absorption (EWA) and stealth technologies. To enhance EWA performances, it is imperative to employ advanced design strategies that incorporate heterogeneous interfaces and multi-scale structures. In this study, we developed a composite elastomer demonstrating exceptional EWA characteristics using a two-step process involving liquid-phase reduction followed by thermal curing. High aspect ratio carbon nanotubes were integrated onto the surface of CoNi nanospheres, creating a multi-scale architecture with heterogeneous interfaces that ranged from zero-dimensional to two-dimensional. This innovative structural design significantly improved the EWA capabilities of the composite elastomer. Notably, even with only 15 wt% filler content, the composite elastomer achieved a minimum reflection loss of −54.4 dB at a thickness of 4 mm, alongside an adjustable effective absorption bandwidth exceeding 60 % of the 2–18 GHz frequency range. Additionally, it exhibited favorable mechanical strength and stretchability, enhancing its practical applicability. This work provides valuable insights into optimizing dielectric and magnetic properties through advanced structural design and underscores the potential for developing effective elastomer absorbers to deal with electromagnetic pollution in complex environment.

Integration of Cu2O-NiTiO3 as an efficient p-n heterojunction visible light photocatalytic system for the simultaneous removal of Cr (VI) and Alizarine Cyanine Green dye

Cu2O loaded NiTiO3 based p-n heterojunction photocatalysts of various proportions have been synthesized by liquid phase reduction process resulting in NiTiO3 nanoparticles dispersed on the surface of Cu2O. Formation of both oxide phases is confirmed from the XRD, HR-SEM and XPS analysis. Heterojunction formation is confirmed by the intimate contact between NiTiO3 and Cu2O as evidenced by HR-TEM. UV-Vis spectra exhibit a red shift indicating the extended visible light absorption. XPS shows the presence of oxidation states of Ni2+, Ti4+, Cu+, Cu2+ and O2-. Heterojunction materials showed enhanced activity for the simultaneous photocatalytic reduction of Cr (VI) and degradation of Alizarine Cyanine Green dye under visible light irradiation. 1:2 ratio of Cu2O and NiTiO3 heterojunction (1C:2N) material exhibits 100% dye degradation in 90 minutes and Cr (VI) reduction in 180 minutes. Higher activity of Cu2O-NiTiO3 p-n heterojunction is ascribed to the effective charge separation and extended visible light absorption

Kirkendall effect enhanced sustained-release Fe-C composites for long-term reductive dechlorination of trichloroethylene: Interfacial reactions and slow-release degradation

Rebounding and lagging during the process of remediating contaminated sites are challenging problems. A potential solution is developing slow-release materials that could assist in the long-term remediation of contaminated sites. This study synthesised a slow-release Fe-C composite (CSBC-nZVI@β-CD), which exhibits a synergistic effect of encapsulated layers and nanocracks, using a liquid-phase reduction method. Furthermore, the reduction and dechlorination mechanism of trichloroethene (TCE) was systematically investigated. The introduction of β-cyclodextrin (β-CD) intensified the Kirkendall effect, forming nano zero-valent iron (nZVI) with abundant radial nanocracks and a litchi-like appearance on the biochar surface. Additionally, β-CD created an encapsulation layer measuring 5–7 nm on the surface of nZVI, improving its electron transport capacity and hydrophobic properties. The CSBC-nZVI@β-CD nanocomposite successfully removed 99 % of TCE in solution within 2 h and accomplished a degradation efficiency of 98.9 % within 15 d. The synergistic effect of the β-CD encapsulating layer and nanocracks facilitated the reactivity and electron-retarding capacity, resulting in a broad pH tolerance and anti-interference ability. Density-functional theory (DFT) calculations and experimental methods were used to study the mechanism of TCE reduction dechlorination; the unique structure of β-CD tended to bind with Fe as well as adsorb TCE, thereby facilitating electron transfer and the enrichment of TCE at the reaction interface. In addition, the sustained-release Fe-C composites reduced the bonding energy required during the TCE degradation reaction and promoted the complete reaction of the product. Overall, CSBC-nZVI@β-CD exhibited significant potential for the long-term remediation of groundwater.

In situ iron coating of amorphous boron and characterization of its energy release behavior

Boron was widely employed as metal fuel in solid propellants for its higher gravimetric and volumetric combustion enthalpies. However, the low melting point and high boiling point of B2O3 on the surface of boron particles significantly hinder its ignition and combustion performance, seriously preventing the full realization of its thermodynamic potential. To address this issue, B@Fe composite fuels with different iron contents from 1.59 % to 7.09 % were prepared via liquid phase reduction in this paper and the quasi-static high temperature oxidation, ignition and combustion reaction characteristics and corresponding mechanism were studied, in order to provide effective modification techniques in supporting the large-scale engineering application of boron as metal fuel. The study results show that B@Fe can effectively reduce the ignition temperature and maximum heat flow temperature of amorphous boron, and increase the maximum mass gain rate. The ignition temperature and maximum heat flow temperature have an exponential function with the iron coating content. Iron coated amorphous boron can effectively shorten the laser ignition delay time by more than 50 %, and significantly change the flame structure, flame evolution process and combustion duration. Both amorphous boron and iron-coated amorphous boron flame showed a multi-layer structure, including the outer green flame, the middle yellow flame and the central incandescent flame. However, with the increase of the iron coating content, the flame height increased from 5.5 cm to 6.3 cm, the flame structure changed from mushroom type to triangle type, and the central incandescent flame area increased significantly. The equivalent combustion duration increased from 975 ms to 1997 ms, and the flame temperature increased from 1288 to 1505 °C. The emission spectra of BO2 and BO lines are captured during combustion. B@Fe with the increase of iron content, a large number of small diameter micropores appear in the condensed combustion products(CCPs) of composite fuels, and a grid-like structure was formed. With the increase of iron coating content, the boron content of condensed combustion products decreases, and the oxygen content increases. The main components of CCP include B, B2O3, B6O, FeB, Fe2B and Fe3B. Based on the ignition combustion experiment of B@Fe composite fuel, ignition combustion analysis model of B@Fe composite fuel was established.

Study on the influence factors of the grain growth type of micro-nano silver powders prepared by liquid-phase reduction method

Abstract The preparation was carried out by liquid-phase reduction method with AgNO3 as the oxidizing agent, ascorbic acid (C6H8O6) as the reducing agent, and polyvinyl pyrrolidone (PVPK30) as the dispersing agent. The effects of silver nitrate concentration, ascorbic acid concentration, PVPK30 concentration, solution PH value before and after the reaction, and the temperature of reaction on average particle size (D50), dispersity, and particle size uniformity of silver particles were investigated by orthogonal experiment L18 (36) with six factors and three levels. The spheroid-like silver particles with good dispersity of 400-600nm and the spheroid-like silver particles with suitable particle size uniformity of 80-100nm were successfully prepared by optimal experiments. The results of the orthogonal experiment show that the molar ratio of the reducing agent to the oxidizing agent plays a decisive role in the type of grain growth. The crystal nucleus will coagulate and grow at a higher molar ratio (⩾1.05). With the increase in molar ratio, the nucleation rate is higher, the grain growth rate is faster, and the size of silver particles is smaller.

Effective removal of nitrate by palygorskite-supported nanoscale zero-valent iron from aqueous solution

Nitrate nitrogen (NO3--N) has become an important pollutant in industrial and agricultural production processes in China. In this study, Palygorskite-supported nanoscale zero-valent iron (nZVI/PG) adsorbent was prepared using the liquid-phase reduction method for the removal of NO3--N from water. Benefiting from the good dispersion uniformity of nZVI on the Palygorskite carrier, the prepared nZVI/PG exhibited a significantly increased specific surface area compared to nZVI, with a noticeable reduction in nZVI aggregation. The Fe/PG mass ratio of 2:1 was found to be the optimal loading ratio for the removal of NO3--N by nZVI/PG, with a removal capacity of 24.36 mg/g and a removal efficiency of 81.23 %, with a nitrogen gas conversion rate of 40.92 %. The removal process of NO3--N by nZVI/PG followed a pseudo-second-order kinetic model, with the removal rate inversely proportional to the initial concentration of NO3--N and directly proportional to the dosage. nZVI/PG exhibited high removal efficiency for NO3--N within the pH range of 2 to 9, with the highest selectivity for NO3--N conversion to N2 observed at pH 5. The main mechanism for the removal of NO3--N by nZVI/PG was found to be adsorption and reduction, with the main products being NH4+-N, NO2--N, and N2.

Degradation kinetics, influencing factors, and mechanisms of polycyclic aromatic hydrocarbons in a Fe3O4-nZVI Fenton-like system

To improve the catalytic performance of nano zero-valent iron (nZVI) in a Fenton-like system, Fe3O4 supported nZVI (Fe3O4-nZVI) was produced by the liquid-phase reduction method and co-precipitation method, then characterized by SEM, EDS, XRD, XPS, and VSM. Fe3O4-nZVI was used as the catalyst in a Fenton-like system to degrade polycyclic aromatic hydrocarbons (PAHs) such as naphthalene (Nap), phenanthrene (Phe), and pyrene (Pyr) in simulated wastewater. The results showed that under the optimization conditions, which were 25℃, 0.6g/L of Fe3O4-nZVI dosage, 3 of the pH in the reaction system, and 10-15mmol/L of the concentration of H2O2, the sequence of degradation efficiency in this system was Phe (99.76%)>Pyr (99.71%)>Nap (98.01%). The reused experiments on Fe3O4-nZVI showed that the degradation efficiency for PAHs remained above 87% after 4 reuses of Fe3O4-nZVI. These results indicated that nanoscale magnetic composites of Fe3O4-nZVI had excellent reactivity, stability, and reuse performance. The fitting parameters of kinetics showed that the degradation of PAHs in the Fenton-like system with the Fe3O4-nZVI catalyst fitted well with the Behnajady-Modirshahla-Ghanbery kinetic model. The radial quenching experiment proved that ·OH was the dominant free radical for the degradation of PAHs in the Fe3O4-nZVI Fenton-like system. Based on the degradation products of PAHs and the related literature, the possible degradation paths of the three PAHs in the Fe3O4-nZVI Fenton-like system were inferred. The above results could provide a reference and basis for the treatment of wastewater containing PAHs by Fe3O4-nZVI Fenton-like technology.

Preparation of Sb@N/F Co-Doped Carbon Nanocomposites and Their Sodium Storage Properties

Antimony (Sb) -based materials with high theoretical capacity (660mAh g-1) and suitable sodium ion embedding potentials are considered as one of the promising anode materials for sodium-ion batteries, which is expected to improve the low capacity of sodium-ion batteries. However, its volume expansion during the charge/discharge process is evident, thus failing to stabilize its capacity advantage. Herein, nanosized Sb particles are induced to form. by introducing N/F co-doped carbon nanosheets (NF-CNs) during the liquid phase reduction process, which alleviates the volume expansion phenomenon of Sb and prevents Sb aggregation and pulverization during the charge/discharge process. Secondly, the Sb nanoparticles can contact with the electrolyte solution sufficiently and shorten the ion diffusion route, thus improving the kinetic characteristics of the material. The introduced carbon matrix not only prevents agglomeration of Sb nanoparticles during the cycling process, but also provides a highly conductive pathway for the rapid ion and electron transfer. Based on the above optimization, the sodium storage performance of the Sb@NF-CNs anode is significantly improved, and the assembled sodium-ion battery has a reversible capacity of 304. 7mAh g-1 after 50 cycles at the current density of 0. 1A g-1 and a reversible capacity of 163mAh g-1 after 200 cycles at the current density of 1. 0A g-1 with excellent rate performance.

A novel asymmetric superwetting filter prepared by easily mass-produced strategy for high-efficient and switchable water/oil filtration

All-purpose materials with on-demand oil/water separation property have received broad attention recently. Herein, a filter paper (FP)-based filter with asymmetric wettability was designed and fabricated via simple combination of liquid phase reduction route with symmetry adhesion method. The fabricated filter exhibits underoil superhydrophobic (UOSHP) and underwater superoleophobic (UWSOP) property. Especially, the good underliquids lyophobicity is still maintained after tape peeling and corrosive, organic solvents treatments. By fixing the hydrophobic (HO) side of filter facing up, the water/light oil mixtures and oil-in-water (O-in-W) emulsions can be highly efficient separated, and the water/heavy oil mixtures and water-in-oil (W-in-O) emulsions are able to be separated with the HI side facing up. The separation efficiencies for water/oil mixtures and oil/water emulsions are higher than 98% and 99.1%, respectively. The study offers a new idea for the preparation of asymmetric superwetting materials with good stability and on-demand water/oil separation capability.

Degradation mechanism and ecotoxicity analysis of levofloxacin by palladium-modified nano zero-valent iron doped coconut shell biochar

The palladium-modified nano zero-valent iron (nZVI) doped coconut shell biochar (Pd-nZVI/BC) was successfully obtained through bimetallic modification and liquid-phase reduction. The synthesized Pd-nZVI/BC was further enhanced by the addition of an H2O2 co-catalyst for the removal of antibiotic levofloxacin (LVF). Results demonstrated that removal of LVF by Pd-nZVI/BC accomplished 94.6 % under proper conditions. Adsorption and degradation processes were involved in the LVF removal, and the predominant free radicals were •OH and •O2-. Adsorption relied mainly on electrostatic interactions, π-π interactions, and hydrogen bonding. While demethylation, deamidation, quinolone ring aldolization, depiperazinylation, deacetylation, decarboxylation, dehydroxylation, and oxidative breakage of the piperazine ring occurred during the degradation processes. Based on the degradation pathways, the ecotoxicity of LVF and its degradation intermediates were compared and assessed. Results implied that majority of the antibiotic LVF pollutant was eliminated or mineralized, and the toxicity potential of LVF was reduced in the Pd-nZVI/BC system. Simultaneous biochar utilization and pollutants removal could be achieved.

Effect of pH on the fabrication of lauric acid/Ag phase change nanocapsules via liquid-phase reduction

Phase change nanocapsules can be dispersed in fluids to form latant functional thermal fluids (LFTFs), which can serve as effective coolants for extending the lifespan of electronic devices. For this purpose, it is significant to prepare phase change capsules that possess excellent heat storage capacity, thermal conductivity, and suspension stability. In this paper, lauric acid/silver composite phase change nanocapsules were prepared by liquid-phase reduction method. To investigate the effect of pH value on capsule synthesis, six phase change capsule samples were prepared between pH values of 2.6–4.6. The results indicate that the prepared nanocapsules exhibited good heat storage capacity and thermal conductivity under different pH values. However, as pH increases, the silver shell thickness on the nanocapsule surface initially decreases and subsequently increases. The silver shell thickness of L3 is the thinnest, measuring 12.5 nm. Correspondingly, the enthalpy and volume encapsulation rate of the phase change capsules first increase and then decrease. The lauric acid/Ag nanocapsules possess a thermal conductivity in the 1.77–4.32 W/(m∙K) range. Further, it is found that pH affects the formation of silver shell on the surface of lauric acid/Ag phase change nanocapsules by influencing the electrostatic interactions between particles, and diffusion in the system, which explains the variation of silver shell thickness with pH value for the six capsule samples. We also found that the thinner the silver shell of the nanocapsules, the more advantageous it is to reduce the density of the capsules, thereby improving their suspension. Therefore, controlling the pH value during the preparation to obtain lauric acid/Ag phase change nanocapsules with thin silver shell thickness plays an important role in improving the overall performance of phase change nanocapsules used for preparing latent functionally thermal fluid.

Synthesis of uniform spherical silver powder without dispersants in a confined impinging-jet reactor

Sliver powder is the most common and extensively utilized precious metal powder in electronics, primarily for electronic paste. Herein, micron-sized spherical silver powder was synthesized via a liquid phase reduction method employing silver nitrate as the source of silver and ascorbic acid as the reducing agent in a confined impinging jet reactor (CIJR). The impact of the molar ratio between silver nitrate and ascorbic acid, the flow rate, and the temperature on the particle size of silver powder was investigated. The optimal process conditions for silver powder are as follows: maintain a molar ratio of 1:1 and control the feeding rate at 10 ml/min while operating at 50 ° C. The confined impinging jet reactor offers enhanced control over reaction conditions during the synthesis of silver powder, surpassing the capabilities of traditional batch reactors. The aforementioned optimized methodology was employed to successfully synthesize uniform and spherical silver powder (with an aspect ratio approaching 1) in the low Reynolds number jet, resulting in an average particle size of d50 = 0.83 μm and a standard deviation of 0.07, without the addition of dispersant. The synthesis method presented here improves the performance of silver powder, simplifies the production process, reduces energy consumption, and minimizes waste generation. These advances yield significant environmental and economic benefits. In the future, with the continuous development and optimization of microreactor technology, this synthesis method is anticipated to play a more prominent role in the commercial-scale production and application of micrometer-sized silver powder.

Trace silver doping improved the efficiency of copper-based Fenton-like catalysts cathode for wastewater treatment

The treatment of highly concentrated and recalcitrant organic pollutants in industrial wastewater has garnered significant attention, with Fenton oxidation emerging as a promising approach. However, traditional iron-based Fenton reagents present certain limitations, and copper-based Fenton systems are often less efficient. Thus, it is necessary to develop innovative copper-based Fenton catalytic materials. In this study, Cu₂O and Ag-modified activated carbon fibers (Cu₂O-Ag@ACF) were synthesized via liquid-phase reduction. The composition, structure, and morphology of Cu₂O-Ag@ACF were systematically characterized. The Cu₂O-Ag@ACF was employed as a functionalized cathode in the electro-Fenton process to degrade a highly concentrated organic pollutant solution, with methylene blue serving as a model contaminant. The loading of Cu₂O and Ag not only enhances the electrochemical performance of ACF but also improves its Fenton oxidation efficiency. Cu₂O-Ag@ACF exhibited less than 1 % performance degradation after five cycles of use, highlighting its potential for industrial applications under simulated realistic conditions. Moreover, the electro-Fenton system parameters, including current density, pH, electrode spacing, and solution temperature, were optimized. Under the optimal conditions, the degradation rate of methylene blue by Cu₂O-Ag@ACF reached 92.8 % within 120 minutes. Kinetic analysis indicated that the reaction followed a first-order kinetic model, with a rate constant of 0.253 min⁻¹. Furthermore, this study revealed that trace silver doping significantly accelerated the generation of reactive oxygen species, thereby enhancing the efficiency of the Cu-based Fenton-like catalysts. In conclusion, this work presents a convenient strategy for the sustainable and efficient purification of industrial wastewater, contributing to the improvement of human life quality.

Pd Nanoparticles Loaded on Cu Nanoplate Sensor for Ultrasensitive Detection of Dopamine.

The detection of dopamine is of great significance for human health. Herein, Pd nanoparticles were loaded on Cu nanoplates (Pd/Cu NPTs) by a novel liquid phase reduction method. A novel dopamine (DA) electrochemical sensor based on the Pd NPs/Cu/glass carbon electrode (Pd/Cu NPTs/GCE) was constructed. This sensor showed a wide linear range of 0.047 mM to 1.122 mM and a low limit of detection (LOD) of 0.1045 μM (S/N = 3) for DA. The improved performance of this sensor is attributed to the obtained tiny Pd nanoparticles which increase the catalytic active sites and electrochemical active surface areas (ECSAs). Moreover, the larger surface area of two-dimensional Cu nanoplates can load more Pd nanoparticles, which is another reason to improve performance. The Pd/Cu NPTs/GCE sensor also showed a good reproducibility, stability, and excellent anti-interference ability.

Data-driven designed low Pt loading PtFeCoNiMnGa nano high entropy alloy with high catalytic activity for Zn-air batteries

Developing low Pt loading and high-activity oxygen electrocatalysts is necessary to promote large-scale fuel cell applications. By data-driven and density functional theory calculations, PtFeCoNiMnGa nano high entropy alloy (HEA) was synthesized through liquid-phase reduction and H2 calcination method and loaded on carbon nano-tube (CNT). Due to high entropy, electronic modulation, and cocktail effects, PtFeCoNiMnGa HEA catalyst shows great catalytic activity in oxygen evolution/reduction reaction (OER/ORR). The PtFeCoNiMnGa/CNT showed a low overpotential of 243 mV for OER, and for ORR a mass activity of 1.12 A mgPt−1 (5.3 times than Pt/C). Moreover, the PtFeCoNiMnGa/CNT showed high durability by maintaining 95 % of its initial performance for up to 50 h. In addition, the zinc-air battery assembled with PtFeCoNiMnGa/CNT as the cathode catalyst had an open-circuit potential of 1.52 V and an energy density of 130.6 mW cm−2, and was able to operate stably for 120 h without any significant degradation.

Degradation Efficiency and Mechanism of Tetracycline in Water by Activated Persulfate Using Biochar-Loaded Nano Zero-Valent Iron.

Tetracycline (TC) contamination in water is one of the key issues in global environmental protection, and traditional water treatment methods are difficult to remove antibiotic pollutants.Therefore, efficient and environmentally friendly treatment technologies are urgently needed. In this study, activated persulfate (PS) using a biochar-loaded nano zero-valent iron (BC-nZVI) advanced oxidation system was used to investigate the degradation effect, influencing factors, and mechanism of TC. BC-nZVI was prepared using the liquid-phase reduction method, and its structure and properties were analyzed by various characterization means. The results showed that nZVI was uniformly distributed on the surface or in the pores of BC, forming a stable complex. Degradation experiments showed that the BC-nZVI/PS system could degrade TC up to 99.57% under optimal conditions. The experiments under different conditions revealed that the iron-carbon ratio, dosing amount, PS concentration, and pH value all affected the degradation efficiency. Free radical burst and electron paramagnetic resonance (EPR) experiments confirmed the dominant roles of hydroxyl and sulfate radicals in the degradation process, and LC-MS experiments revealed the multi-step reaction process of TC degradation. This study provides a scientific basis for the efficient treatment of TC pollution in water.

Kinetics of Ag-coated Cu particles prepared by liquid phase reduction

Ag-coated Cu particles prepared by electroless deposition are highly anticipated bimetallic materials with wide electronic applications. However, only limited progress has been made in the kinetics and mechanism of chemical silver deposition on copper particles. A series of Ag-coated copper particles with uniform and continuous silver coverings were successfully prepared by varying the reaction temperature. The study used the Johnson-Mehl-Avrami model to conduct kinetic analyses, revealed the nucleation and growth mechanisms and yielded corresponding kinetic parameters. The temperature was found to have a proportional correlation with the reaction rate constant ( k), with an activation energy of approximately 10.01 kJ/mol. These particles exhibit exceptional oxidation resistance. Moreover, the particles were used to develop a new conductive paste with high electrical conductivity.

Fabrication of fabric-based piezoresistive sensors based on chemically deposited fabric silver electrodes and PDMS-MWCNTs/CB composite films with thermally expandable microspheres

Optimizing the fabrication process of fabric electrodes and creating active layers with a controlled pore structure is crucial for advancing high-performance flexible pressure sensors. This work proposes an approach to manufacturing fabric-based piezoresistive sensors. Specifically, it utilizes the liquid-phase chemical reduction method with microdroplet jetting technology and the thermally expandable microsphere foaming method. The impact of conductive material filling content and the microsphere expansion process on the active layer performance was investigated. Additionally, the electrical properties of fabric metal silver electrodes were evaluated, along with the sensing capabilities and applications of the sensors. The results reveal that the electrodes exhibit an average sheet resistance of 0.023 Ω sq−1. The sensor displays a sensitivity of 0.21 kPa−1, with a response-recovery time of approximately 300/200 ms and repeatability over 5000 s. Human motion signal tests of the sensor demonstrate its potential in healthcare and sports monitoring applications.

Complexing agent-assisted Cr(VI) removal in a continuous fixed-bed system with nanoscale Fe0/NaA molecular sieve membrane supported on nickel foam

Complexing agents (CAs) can be used for the removal of Cr(VI) via nanoscale Fe0 (nZVI) reduction in cost-effective manner. However, nZVI is prone to aggregation and passivation, and some conventional CAs are toxic and difficult to biodegrade, potentially causing secondary pollution. Therefore, selecting an environmentally friendly CA for assisting in the removal of Cr(VI) via supported nZVI is imperative. Herein, NaA molecular sieve membrane-supported nZVI (nZVI/NaA-NF) was prepared via the secondary growth and liquid-phase reduction method using nickel foam (NF) as the carrier. The physicochemical characteristics of nZVI/NaA-NF before and after reaction were analysed via SEM, EDS, and XPS. A CA-improved nZVI/NaA-NF was used for the effective removal of Cr(VI) in a continuous fixed-bed system. Furthermore, the influences of various experimental factors including the CA type, CA concentration, solution pH, space velocity, and inlet Cr(VI) concentration on Cr(VI) removal were systematically investigated. The results demonstrated that nZVI particles were homogeneously immobilized on the NaA molecular sieve membrane/NF for fresh nZVI/NaA-NF, and tetrasodium iminidisuccinate (IDS-4Na) inhibited the aggregation of Cr(III)/Fe(III) (hydr)oxide precipitates during the reaction. IDS-4Na demonstrated excellent promotive effect on Cr(VI) removal via nZVI/NaA-NF. The breakthrough time for Cr(VI) in the addition of IDS-4Na was considerably longer than that of nZVI/NaA-NF alone. The breakthrough concentration of Cr(VI) only reached 1.1% and 9.9% of the inlet concentration at 220 and 240 min, with an IDS-4Na concentration of 4 mM, a pH of 2.5, and a space velocity of 0.265 min−1. The Bohart–Adams model was appropriate to predict the initial part of Cr(VI) breakthrough curves in the nZVI/NaA-NF fixed bed. The saturated concentration (N0) increased with an increase in inlet Cr(VI) concentration. The Yoon–Nelson model afforded good fitting results for all breakthrough curves of Cr(VI). The k′ value increased with an increase in space velocity, and the τ value decreased.