Wet Process Research Articles

Preparation and properties of polytetrafluoroethylene/zinc oxide antibacterial filaments

AbstractThe potential of polytetrafluoroethylene (PTFE) products as surgical dressings is considerable, yet their absence of antibacterial properties substantially restricts their medical applications. To enhance the utility of PTFE in the medical sector, this research loaded nano zinc oxide (ZnO) particles into the PTFE filament matrix through a wet spinning process. This approach successfully yielded PTFE/ZnO composite filaments with antibacterial properties. The characterization results of the filaments show that when the mass ratio of PTFE to ZnO is 8:1, the filament has the best mechanical performance with a tensile strength of 6.78 MPa and an elongation at break of 274.46%. At the same time, composite antibacterial filaments under different process conditions show excellent antibacterial effects against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with an antibacterial rate of over 99%. The excellent mechanical properties ensure the ability to further process single filaments, which can be woven into fabrics, textiles, and various other products. Therefore, the composite antibacterial filaments with excellent comprehensive performance prepared in this study are expected to be applied in the field of medical fabrics.Highlights Provide new solution ideas for functional PTFE composite filaments preparation. The prepared PTFE/ZnO composite filament has good acid and alkali resistance as well as excellent antibacterial properties, which is expected to broaden the application field of PTFE filaments.

Aged Refuse Recycling to Treat Wastewater from Coffee Processing

Over the last two decades, the use of bioreactors filled with aged refuse extracted from closed areas of landfills has proven to be a viable alternative for the treatment of different types of wastewater. This study presents the results obtained during the evaluation of aged refuse used as filling material for a downflow bioreactor during the removal of the organic load present in wastewater generated in the wet processing of coffee. The tests were carried out over a period of 120 days, with 15 days to start up and stabilize the bioreactor and 105 days to perform treatability tests. The aged refuse, once extracted, was dried and sifted to a particle size of less than 50 mm. The bioreactor used had a cylindrical geometry (Ø = 0.20 m, and h = 3.40 m), and it was fed with hydraulic loads of 50, 100, and 150 L m−3 d−1. The analysis of the data obtained shows that the system studied achieves the removal of 98.3% of the initial organic load when fed with 150 L m−3 d−1. This showcases recycling aged refuse as a technically viable alternative to treat the wastewater generated during coffee processing. Also, the evaluated system has the advantage of needing a short period of time to achieve its stabilization, which turns out to be of great value, especially in its possible use in the treatment of residual water generated in the harvest of agricultural products where the period of harvest is very short.

Fabrication of Flexible Organic Field Effect Transistor Using Patterned Electrospray Deposition

ABSTRACTThe electrospray deposition (ESD) method is a wet process that uses the solution spray formed by an electric field between the needle of a syringe containing the solution and a conductive substrate or an insulated electrode. In this study, we fabricated thin films based on 6,13‐bis(triisopropyl‐silylethynyl) pentacene (TIPS‐pentacene) formed by a new direct patterning ESD method. This method utilizes an electric field applied between the nozzle and patterned electrodes on the substrate. It enables the formation of patterns on materials such as plastic films. Moreover, this ESD method allows for the control of patterned film width using the voltage on a counter‐patterned electrode. These results demonstrate that the patterned TIPS‐pentacene film width can be controlled by controlling voltage. We fabricated a flexible organic field‐effect transistor (OFET) using this method and measured its static electrical characteristics.

Boron-Intercalation Engineering toward Defected 1T Phase-Rich MoBxS2-x-Supported IrOx Clusters for Acidic OER.

The construction of supported Ir-based catalysts can effectively reduce the amount of Ir and generate a synergistic effect that enhances the oxygen evolution reaction (OER) activity and stability, making it one of the effective solutions for optimizing acidic OER catalysts. However, most reported metal oxide supports suffer from poor acid resistance and low electrical conductivity, which are critical for the OER process. Herein, we synthesized a nanosheet-like defected 1T phase-rich MoBxS2-x via a molten salt calcination process, during which the 1T phase was formed, and B was intercalated into MoS2 to protect the 1T phase structure during annealing procedure. After the wet refluxing process, IrOx clusters were uniformly deposited on the surface of MoBxS2-x to form IrOx@MoBxS2-x, which exhibited an overpotential of 168 mV at a current density of 10 mA cm-2 with an Ir loading amount of 25.8 wt %. By comparing the OER performance of IrOx@MoBxS2-x, IrOx@MoS2(Calcinated), and IrOx@MoS2, it is demonstrated that calcination and B intercalation of MoS2 can significantly increase acidic OER performance. This work digs into the application of 1T-MoS2 as an OER catalyst support, providing strategies for the phase and morphology control of 1T-MoS2.

Mechanical and Durability Properties of Rubberized Sulfur Concrete Using Waste Tire Crumb Rubber

The use of rubber crumbs provides a viable solution for alleviating the disposal problem of waste tires. In this study, rubberized sulfur concrete (RSC) was researched to investigate the optimal mixture proportion and to improve the mixing process in terms of compressive strength and durability performance. For the mixture of the RSC, sand, rubber particles, and micro-filler were adopted as aggregates and sulfur was used for the binding material. Moreover, two mixing processes were applied: the dry mixing process and the wet mixing process. Based on the test results, the increment of rubber particles in the mixture led to a decrease in the compressive strength for both the dry and wet mixing processes. To minimize the voids between the sand and rubber particles, the micro-filler was used at 5% of the total volume. The amount of sulfur varied slightly depending on the mixing process: 30% sulfur for the dry mixing process and 34% sulfur for the wet mixing process, respectively. Consequently, compared to the dry mixing process, the wet mixing process increased the bonding force between sulfur and rubber powder due to the simultaneous heating and combining. In toughness, the wet mixing process demonstrates a 40% higher energy absorption capability compared to the dry mixing process. For the durability performance of the RSC, the mixture with 20% rubber particles produced using the wet mixing process exhibited better corrosion and freeze–thaw resistance.

Design and fabrication of ultrathin silicon-based strain gauges for piezoresistive pressure sensor

Ultra-thin (20 μm) silicon strain gauges were fabricated with silicon-on-insulator (SOI) wafer by a newly-conceived wet etching process. Buffered oxide etchant (BOE, NH4F: HF = 6:1) solution with additives of octylamine and octanol was used for wet etching process in which the operating temperature was 50°C. Photoresist as a passivation layer was deposited on the upper side of SOI wafer to minimize strain gauge damage by chemical etchants. Small amount of octylamine and octanol were added to BOE solution to improve surface wettability and SiO2/Si selectivity. The fabricated strain gauges were attached to the pressure diaphragm and the performance of strain gauge was investigated by measuring with the hydraulic pressure system. The resistance changed linearly with tensile and compressive strains. Maximum values of non-linearity, hysteresis, thermal coefficient of resistance (TCR) and sensitivity were -0.341 %, 0.909 %, 4128 ppm/°C and 34.22 mV/V respectively. The fabricated strain gauges might be well applicable to the hydrogen pressure sensor which is detectable for high pressure range (0–900 bar).

Applications of cellulase enzyme in textile industry purified from Bacillus paramycoides S 5

Cellulases are enzymes which breaks down β -1-4-glycosidic bonds present in a complex polysaccharide cellulose. In this study cellulase producing bacteria were isolated from soil samples and efficient cellulase producing bacteria was identified as Bacillus paramycoides S 5 strain by using 16 S rRNA sequencing method. By using the same strain, cellulase enzyme was purified with different methods such as ammonium sulfate precipitation, dialysis, chromatography. The purified enzyme was tested for its applications in textile industry. The applications of cellulase enzymes in txtile industry includes wet processing, biostoning, biopolishing, softening and removal of stain from the clothes. In the present study of applications of purified cellulase enzyme in textile industry, after testing for wet processing and softening of fabrics giving the good biofinishing effects on selected fabric. In another application that is in removal of stain from cloth shows positive effect and found that cellulase has capability to remove stain colour from the cloth, later on cellulase applicability also tested on fabrics with respected to biopolishing which helps to remove the fabrics and microfibrils from the cloth giving a soft appearance to cloth. Finally cellulase was also tested for biostoning.

Band Alignment and Surface Photo-Voltage Analysis of C-Si/Siox/Poly-Silicon Passivating-Contact Stacks Through X-Ray Photoelectron Spectroscopy.

Ultrathin SiOx layers and c-Si/SiOx interfaces find application in tunnel-oxide passivated contacts (TOPcon) for high-efficiency silicon solar cells. Here, we investigate their detailed microscopic properties, with specific attention for the case of c-Si(100) substrates, capped either by p-type or n-type poly-silicon layers [c-Si/SiOx/poly-Si (p+) or c-Si/SiOx/poly-Si (n+)]. Our focus is on the effects of the substrate preparation conditions (either by a dry-plasma or wet SiOx process) and the high-temperature annealing step (as required for the poly-Si crystallization) on the SiOx stoichiometry and its microscopic structure. Through advanced photoemission techniques, we find a clearly decreased valence band offset between the c-Si and SiOx (from 4.5 eV to 4.15 eV) when comparing the dry SiOx with the wet SiOx process, independent of the SiOx film thickness, but correlating with the relative fraction of sub-stochiometric Si states. We lastly examine the magnitude of band-bending of the contact structure through controlled in-situ exposure to light of the surfaces and subsequent tracking of core and valence band levels via a surface photovoltage and a junction photo-voltage (JPV) effect. By analyzing this JPV effect qualitatively, we find it to be proportional to the expected quasi fermi level splitting within the c-Si wafer.

How Wetting and Drainage Cycles and Wetting Angle Affect Capillary Air Trapping and Hydraulic Conductivity: A Pore Network Modeling of Experiments on Sand

Entrapped air in porous media can significantly affect water flow but simulations of air entrapment are still challenging. We developed a pore-network model using quasi-static algorithms to simulate air entrapment during spontaneous wetting and subsequent drainage processes. The model, implemented in OpenPNM, was tailored to replicate an experiment conducted on a medium-sized unconsolidated sand sample. We started building the model with three types of relatively small networks formed by 54,000 pore bodies which we used to calibrate basic network topological parameters by fitting the model to the water retention curve and the saturated hydraulic conductivity of the sand sample. Using these parameters, along with X-ray image data (µCT), a larger network formed by over 250,000 pore bodies was introduced in the form of stacked sub-networks where topological parameters were scaled along the z-axis. We investigated the impact of two different contact angles on air entrapment. For a contact angle of 0, the model showed good agreement with the experimental data, accurately predicting the amount of entrapped air and the saturated hydraulic conductivity. On the contrary, for a contact angle of π/4, the model provided reasonable accuracy for saturated hydraulic conductivity but overestimated the amount of entrapped air. Overall, this approach demonstrated that a reasonable match between simulated and experimental data can be achieved with minimal computational costs.

Extraction, Characterization, and Utilization of Psidium Guava Leaf Extract in Textile Wet Processes

Extraction, Characterization, and Utilization of Psidium Guava Leaf Extract in Textile Wet Processes

Life After Death: Re‐Purposing End‐of‐Life Supercapacitors for Electrochemical Water Desalination

AbstractThis study explores the potential of re‐purposing end‐of‐life commercial supercapacitors as electrochemical desalination cells, aligning with circular economy principles. A commercial 500‐Farad supercapacitor was disassembled, and its carbon electrodes underwent various degrees of modification. The most straightforward modification involved NaOH‐etching of the aluminum current collector to produce free‐standing carbon films. More advanced modifications included CO2 activation and binder‐added wet processing of the electrodes. When evaluated as electrodes for electrochemical desalination via capacitive deionization of low‐salinity (20 mM) NaCl solutions, the minimally modified NaOH‐etched carbon electrodes achieved an average desalination capacity of 5.8 mg g−1 and a charge efficiency of 80 %. In contrast, the CO2‐activated, wet‐processed electrodes demonstrated an improved desalination capacity of 7.9 mg g−1 and a charge efficiency above 90 % with stable performance over 20 cycles. These findings highlight the feasibility and effectiveness of recycling supercapacitors for sustainable water desalination applications, offering a promising avenue for resource recovery and re‐purposing in pursuing environmental sustainability.

Reliable fabrication of 3D freestanding nanostructures via all dry stacking of incompatible photoresist

Three-dimensional (3D) free-standing nanostructures based on electron-beam lithography (EBL) have potential applications in many fields with extremely high patterning resolution and design flexibility with direct writing. In numerous EBL processes designed for the creation of 3D structures, the multilayer resist system is pivotal due to its adaptability in design. Nevertheless, the compatibility of solvents between different layers of resists often restricts the variety of feasible multilayer combinations. This paper introduces an innovative approach to address the bottleneck issue by presenting a novel concept of multilayer resist dry stacking, which is facilitated by a near-zero adhesion strategy. The poly(methyl methacrylate) (PMMA) film is stacked onto the hydrogen silsesquioxane (HSQ) resist using a dry peel and release technique, effectively circumventing the issue of HSQ solubilization by PMMA solvents typically encountered during conventional spin-coating procedures. Simultaneously, a dry lift-off technique can be implemented by eschewing the use of organic solvents during the wet process. This pioneering method enables the fabrication of high-resolution 3D free-standing plasmonic nanostructures and intricate 3D free-standing nanostructures. Finally, this study presents a compelling proof of concept, showcasing the integration of 3D free-standing nanostructures, fabricated via the described technique, into the realm of Fabry-Perot cavity resonators, thereby highlighting their potential for practical applications. This approach is a promising candidate for arbitrary 3D free-standing nanostructure fabrication, which has potential applications in nanoplasmonics, nanoelectronics, and nanophotonics.

Enhanced mechanical and electrical properties of single-walled carbon nanotube fibers via electric field-assisted wet spinning

Researchers have been working on creating fibers from single-walled carbon nanotubes (SWCNTs) that have optimal properties at the molecular level. However, the prepared SWCNT fibers have showed much lower properties than the ones predicted by theory because the interactions between SWCNTs and SWCNT bundles were not strong enough due to the poor alignment of SWCNTs in the fibers. In this study we improved the mechanical and electrical properties of the SWCNT fibers by using an electric field during the wet spinning process. The electric field, which was applied to the top of the syringe plunger and the tip of the spinneret, oriented the SWCNTs in the chlorosulfonic acid dope solution in a nozzle system, and made them more compact. The SWCNT fibers produced through our process exhibited a significant improvement in their properties. Specifically, we observed a 117.5 % increase in tensile strength and a 140.5 % increase in electrical conductivity. Importantly, these enhancements were achieved without the need for any additional post-treatments. This clearly demonstrates the effectiveness of our current wet spinning method.

Macrokinetics of ammonium sulfite oxidation inhibited by sodium thiosulfate in wet ammonium flue gas desulfurization

AbstractThe oxidation of ammonium sulfite must be inhibited to improve the economy and cycle performance of the ammonia flue gas desulfurization process. A stirred bubbling reactor was used to investigate the macrokinetics of oxidation inhibition of ammonium sulfite by sodium thiosulfate in wet ammonia desulfurization. The effects of initial concentration, Na2S2O3 concentration, pH value, gas flow rate, and temperature on the oxidation rate were discussed. The results show that the apparent activation energy of the reaction is 37.3 kJ/mol. The macrokinetics equation of sodium thiosulfate inhibiting sulfite oxidation in the ammonia desulfurization process was established. Combined with the kinetic model, it is inferred that the rate of sodium thiosulfate inhibiting ammonium sulfite oxidation is controlled by the intrinsic chemical reaction. The results can provide a reference for the regeneration of ammonium sulfite in the wet ammonia desulfurization process.

Effects of zirconium diboride addition on porosity reduction in laser metal deposition of tungsten carbide–cobalt cermet material

Laser metal deposition of tungsten carbide–cobalt (WC-Co) cermet material is a promising means of improving the wear resistance of metal products. However, laser metal deposition of WC-Co has constraints on its practical use because a clad bead of WC-Co often includes numerous gas pores. Earlier studies have found CO gas generation in a molten pool by reaction of carbon and oxygen to be the main cause of gas porosity in a WC-Co clad bead. Preventing the gas reaction is important to obtain clad beads with few pores. The addition of elements with strong affinity for oxygen, such as aluminum, was found to be effective for porosity reduction in a clad bead. However, the addition of highly reactive pure aluminum particles on WC-Co powder presents some difficulties for industrial use. For this study, zirconium diboride (ZrB2), a chemically stable compound, was used as an additive to WC-Co powder. After WC-Co powder with adhered ZrB2 particles was prepared using a wet granulation process, laser metal deposition was conducted. Zirconium stemming from the dissolution of ZrB2 in the molten pool was found to have the effect of trapping oxygen elements as solid zirconium oxides. Consequently, gas generation in the molten pool by the reaction of carbon and oxygen was restrained. Clad beads having few pores and fine microstructures were obtained. Observations of the molten pool behavior taken using a high-speed camera indicated that ZrB2 addition drastically improves process stability compared to processes using conventional WC-Co powder.

Formation Mechanism and Prevention of Cu Undercut Defects in the Photoresist Stripping Process of MoNb/Cu Stacked Electrodes

The Cu undercut is a recently discovered new defect generated in the wet stripping process of MoNb/Cu gate stacked electrodes for thin-film transistors (TFTs). The formation mechanism and preventive strategy of this defect were identified and investigated in this paper. The impact of stripper concentration and stripping times on the morphology and the corrosion potential (Ecorr) of Cu and MoNb were studied. It is observed that the undercut is Cu tip-deficient, not the theoretical MoNb indentation, and the undercut becomes severer with the increase in stripping times. The in-depth mechanism analysis revealed that the abnormal Cu undercut was not ascribed to the galvanic corrosion between MoNb and Cu but to the local crevice corrosion caused by the corrosive medium intruding along the MoNb/Cu interface. Based on this newly found knowledge, three possible prevention schemes (MoNiTi (abbreviated as Mo technology development (MTD) layer/Cu), MoNb/Cu/MTD, and MoNb/Cu/MoNb) were proposed. The experimental validation shows that the Cu undercut can only be completely eliminated in the MoNb/Cu/MTD triple-stacked structure with the top MTD layer as a sacrificial anode. This work provides an effective and economical method to avoid the Cu undercut defect. The obtained results can help ensure TFT yield and improve the performance of TFT devices.

Soil utilization of solid waste: Small-strain dynamic properties and microscopic mechanism of phosphogypsum-modified coastal cement soil

Phosphogypsum (PG), a solid waste from the wet process phosphoric acid industry, but the utilization rate is low at present. The effect of phosphogypsum and cement on small strain dynamic characteristics of coastal soft soil was studied by resonance column test, and characterize the micro-mechanisms of the specimens by SEM and EDS test. The results show that the dynamic shear modulu (G) and the damping ratio (D) firstly increase and then decrease with the PG level increasing. PG can motivate the formation of hydrated calcium silicate (C–S–H) gel and react with calcium aluminate to form calcium. The critical value for assessing the dynamic behavior of PCS under small strain is γ = 10−4. The Hardin-Drnevich model eigenmodel can well characterize the dynamics of the PCS. Based on this model, a modified dynamic model is established to describe the dynamic characteristics of PCS. The microscopic results showed that the addition of phosphogypsum promoted the production of hydration products and made the particles more closely arranged. The content of this study provides a new reference for the application of solid waste phosphogypsum in cement soil.

CÁLCULO DE LA HUELLA VIRTUAL DEL AGUA EN EL PROCESO PRODUCTIVO Y BENEFICIADO DE CAFÉ (Coffea arabica L.) EN HUATUSCO, MÉXICO, UTILIZANDO EL SOFTWARE CROPWAT 8.0

<p><strong>Background:</strong> The use and expenditure of water within agriculture is of vital importance, especially in coffee farming, therefore it is very important to know that the virtual water in the production of coffee beans, as well as in the process of wet processing (transformation of cherry coffee to dry parchment coffee), so far there is no data on the use of virtual water in coffee production in the study region. <strong>Objective:</strong> To determine the virtual water (green and gray) calculation of the virtual footprint by means of the FAO program CROPWAT 8.0 and the calculation of water expenditure in coffee mills in the region of Huatusco, Veracruz. <strong>Methodology:</strong> The program CROPWAT 8.0 was obtained, and normal climatological data were reviewed to obtain the data and to be able to make the calculations to obtain the virtual footprint, subsequently the water expenditure was measured in five wet coffee mills, for this purpose the mills were visited during the harvest season and the measurements could be made. <strong>Results:</strong> A total green and gray virtual footprint of 977.61 m<sup>3</sup>/kg of coffee produced in the field production process was estimated. In relation to the virtual water expenditure in the wet coffee mills where water expenditure was measured: two of the five mills analyzed had the following data: The third mill reached an expense of 566 m<sup>3</sup>/kg of processed cherry coffee and the five mill had an amount of 162 m3/kg of processed cherry coffee and an average of 155.13 m<sup>3</sup>/kg of processed coffee. In total, the virtual footprint obtained: green, gray and water consumption in the processing process was 1132.73 m<sup>3</sup>/kg of parchment coffee. The blue virtual footprint was considered zero since irrigation is not used in the region for coffee production. <strong>Implications:</strong> The data found are the pioneers in the calculation of the virtual footprint of the species <em>(Coffea arabica</em> L.) more studies on this subject are needed in the region which will raise awareness about the virtual footprint generated in the coffee production and processing process, as well as proposed alternatives for a more sustainable use. <strong>Conclusions:</strong> The virtual footprint obtained was high in the study region and like studies carried out in other countries, which indicates that there is an awareness of how much water is used in the production and processing of coffee, as well as its impact in the short, medium and long term.</p>

Influence of temperature and pressure on the wetting progress in 21700 lithium‐ion battery cells: Experiment, model, and lattice Boltzman simulation

The electrolyte filling and subsequent wetting of the active material is a time‐critical process in the manufacturing of lithium‐ion batteries. Due to the metallic cell housing, the process phenomena are insufficiently accessible, preventing the replication of the wetting processes by mathematical or simulative methods and hindering efforts to accelerate the wetting process. Therefore, this publication employs a glass cell housing for electrolyte filling of a 21700 cylindrical cell to investigate the wetting at different temperatures and process pressures. In parallel, a mathematical replication of the wetting, as well as a lattice Boltzmann pore‐scale simulation, is used to evaluate the influence of these varying process boundary conditions. The results show a strong temperature dependence on electrolyte wetting and the positive effect of pressure changes in the wetting process. These findings are particularly relevant to the process design of large‐scale cylindrical cell manufacturing.

Impact of applied and preceding pressure on performance and reversible swelling of lithium-ion pouch cells with varying microporous separators

During the compression of battery cells in battery pack production, high forces occur temporarily due to the viscoelastic behavior of the cell components. The magnitude of these forces depends on the compression speed. Shortening the production time and, thus, increasing the compression speed is desirable for cost reduction. However, it must be ensured that the cells are not negatively affected by increased forces during production. The impact of these preceding forces, acting on the cell before operation, and the applied force during operation on the performance and the reversible swelling of 5Ah NMC811/graphite lithium-ion pouch cells are investigated in this study. To this end, a universal compression testing machine was adapted to enable high-precision thickness measurements under defined constant pressure and temperature conditions. In addition, the effects of different microporous separators manufactured via dry process and wet process in an otherwise identical cell configuration were investigated. In the test procedure, the pressure was incrementally increased from 0.01MPa to 2.5MPa. Each measurement was performed at the distinct constant pressure levels, followed by a subsequent measurement at a reference pressure of 0.2MPa to evaluate the impact of the preceding step. The results revealed that elevated preceding pressures on the cell can reduce the discharge rate capability on higher C-rates by up to 11%. The discharge rate capability of the cells with the wet-processed separator was more significantly influenced by increasing applied and preceding pressure than for those with the dry-processed separator. It was found that the reversible swelling of the cell was reduced by applying higher pressures, whereas elevated preceding pressure increased the reversible swelling. The results of this study suggest that cells should not be subjected to excessive forces before operation, for instance, during battery pack production, as this can negatively affect performance and swelling behavior. Furthermore, the mechanical stability of the separator during the pack production process should also be considered when designing a cell.