Film Diffusion Research Articles

Fast Gold Recovery from Aqueous Solutions and Assessment of Antimicrobial Activities of Novel Gold Composite

A novel porous gold polymer composite was prepared by the functionalization of a glycidyl methacrylate-based copolymer (pGME) with ethylene diamine (pGME-en), and activation by gold (pGME-en/Au), in a simple batch adsorption procedure in an acid solution, at room temperature. Detailed characterization of the pGME-en before and after activation was performed. The main focuses of this research were the design of a method that can enable the recovery of gold and the reuse of this multipurpose sorbent as an antimicrobial agent. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis pointed out amine groups as the primary binding sites for Au activation, while hydroxyl groups also contributed to the chelation reaction. pGME-en exhibited fast gold adsorption with an adsorption half-time of 5 min and an equilibrium time of 30 min. The maximal adsorption capacity was about 187 mg/g. The analysis of sorption experimental data with a non-linear surface reaction and diffusion-based kinetic models revealed the pseudo-second-order and Avrami model as the best fit, with unambiguous control by liquid film and intra-particle diffusion. The biological activity studies against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Candida albicans revealed moderate activity of pGME-en/Au against different bacterial and fungal species. pGME-en/Au was stable in a saline solution, with a release of approximately 2.3 mg/g after 24 h.

A green synthesis of cellulose nanocrystals biosorbent for remediation of wastewater containing industrial dye

A novel cellulose nanocrystals biosorbent (CNCs) that has been synthesized, characterized, and used to remove indigo carmine blue (ICB) dye from wastewater. The characteristics of the cellulose nanocrystals biosorbent were assessed using various methods, including N2 adsorption-desorption isotherm, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), SEM, and Fourier-transform infrared spectroscopy (FTIR). To examine the influence of various reaction parameters, for instance temperature, initial dye concentration, pH, and contact time, on the adsorption of the ICB, a comprehensive study was carried out. Under the ideal conditions, the highest adsorption capacity reached 746.24 mg/g, achieved after 100 min at pH 4. The Langmuir model was employed to describe the adsorption isotherm, and the pseudo-second-order model was applied to describe the kinetics of the adsorption process. The adsorption of ICB is more accurately represented by the Langmuir model rather than the Freundlich model, indicating the formation of a selective monolayer on the CNCs surface. Both film and intraparticle diffusion contribute to the adsorption of the dye. The adsorption process is characterized as chemisorption, with an adsorption energy of 17 kJ/mol. The values of enthalpy change (∆H°) and entropy change (∆S°), which are 86.55 kJ/mol and 303.69 J/mol/K, respectively, suggest that the removal process of ICB is endothermic. The interaction mechanism between ICB dye and CNCs biosorbent likely involves various forces, such as π-π interactions, hydrogen bonding, electrostatic interactions, and pore filling. Furthermore, even after undergoing five consecutive cycles of reuse, the results consistently showed that the CNCs biosorbent maintained its effectiveness. These findings indicate that porous CNCs hold significant promise as an innovative biosorbent for the treatment of wastewater containing ICB.

Single-stage microwave-irradiated activated carbon from corncob for ammonia nitrogen removal: Batch, attraction mechanism and regeneration studies

The existence of ammonia nitrogen (NH3-N) in water reservoirs contribute to the poor quality of water, thus affecting aquatic life and human. Therefore, the goal of this study was to treat NH3-N from wastewater using activated carbon derived from corncob (CCAC). The CCAC was produced through a single-stage microwave irradiation technique where carbon dioxide (CO2) was utilized for the gasification effect. The CCAC demonstrated a mesoporous surface area measuring 645.97 m2/g, accompanied by a total pore volume of 0.41 cm3/g. Furthermore, the average pore diameter was determined to be 2.74 nm. The equilibrium study revealed that NH3-N uptakes and NH3-N percentage removal increased (9.11–59.49 mg/g) and declined (91.10–59.49 %), respectively, when NH3-N initial concentration increased from 10 to 100 mg/L. At a solution temperature of 30 °C, the greatest adsorption capacity for NH3-N was observed, reaching 59.49 mg/g. Similarly, at a pH of 4, the adsorption capacity peaked at 71.46 mg/g. Adsorption of NH3-N onto CCAC obeyed the Langmuir isotherm model and pseudo-first order (PFO) kinetic model. It was determined that the maximum monolayer coverage, Qm was 78.05 mg/g. The investigation of the mechanism indicated that film diffusion is the rate-determining step in the adsorption process. In the thermodynamic section, the parameters of ΔH°, ΔS°, ΔG°, and Ea were computed to be −1.70 kJ/mol (exothermic in nature), 0.05 kJ/mol.K (elevated randomness at the solid-liquid interface), −18.22 kJ/mol (spontaneous) and 1.89 kJ/mol, respectively. The surface of CCAC was occupied with different functional groups namely nitro compound, aromatic compound, and phenol. These functional groups formed hydrogen bonding with NH3-N, thus aiding NH3-N removal from wastewater. In the regeneration study, CCAC can withstand up to 3 cycles before its yield dropped to 33.21 % and its adsorption capacity dropped to 10.15 %.

Optimization of leaching parameters for the extraction of copper from hematite-dominated copper ore using Response Surface Methodology (RSM)

The optimization of recovery of copper from Akiri hematite-dominated copper ore using hydrometallurgy was investigated in this study. The Akiri copper ore deposit hosts a high-grade copper mineral from which copper metal can be extracted. However, the ore is dominated by gangue minerals that need to be mechanically reduced for efficient copper recovery. The purpose of this study is to optimize the extraction of the metal from hematite-dominated copper ore. The experiments that were carried out in the course of this study include crushing, pulverization,mineralogical and chemical characterizations of the sample and sulpheric acid leaching. Response surface methodology was used to optimize the system parameters namely;temperature, concentration of the leachant and contact time so that an efficient method will be developed for the extraction of copper.Chalcopyrite, covellite and cuprite are the copper minerals while the gangues minerals were quartz ,mica, hematite,etc.on the characterization of the copper ore. The major oxides in the ore are hematite ,copper oxide and silica and revealed that the ore contains 4.61% copper and 65.8% iron. Effect of three independent factors like concentration ,temperature and contact time for copper extraction from the hematite-dominated copper ore was studied.Central composite design method was applied to the proposed quadratic model that connect the factors used for best copper extraction at the best process condition. The work shows that concentration of the acid was the best efficient factor for copper extraction compare to temperature and contact time. This may be as a result of high value of F-statistics for the concentration of the leachant, which effects to high level of copper extraction.Experimental and predicted values for weight loss from the copper ore were obtained as 39.10% and 39.03% at optimum conditions, respectively. The optimum conditions of 1.5M acid concentration, 90oC reaction temperature and 90minutes contact time were obtained and from which 6.64%Cu at recovery of 92.0% and 2.31%Fe was obtained without stirring. Also, the ore was subjected to leaching with stirring at 400rpm with the optimum conditions obtained to know the effect. The grade obtained was 7.84% Cu at recovery of 83.51% and iron content 5.47%. This shows that leaching without stirring is the best option against leaching with stirring to extract the copper and to reduce the iron and other gangues contents in the copper ore.The activation energies were estimated as 13.20kJ/mol and 22.67kJ/mol for liquid film diffusion and diffusion product layer respectively, the values indicate that the leaching rate is controlled by diffusion process.

Synthesis, characterization, and phytotoxicity evaluation of Ce/Zr bimetallic oxides as adsorbents for nitrate decontamination from water

The Ce/Zr bimetallic oxides with varying atomic ratios were synthesized by sol-gel combustion technique and used as adsorbents for the nitrate decontamination from water. Thermogravimetric analysis (TGA), energy dispersive X-ray spectroscopy (EDX) aided FESEM, X-ray diffraction (XRD), and Brunauer-Emmett-Teller surface area analysis (BET) were utilized to characterize the synthesized bimetallic oxides thoroughly. Compared to bimetallic oxides with various Ce/Zr ratios (1:1, 1:2, 1:3, 1:4, and 2:1), bimetallic oxide with an atomic ratio of Ce/Zr (1:3) showed a superior and more efficient performance for capturing nitrate ions. The optimum conditions for maximal nitrate removal were an adsorbent dosage of 0.07 g/L, a solution pH of 7.0, a contact time of 40 min, and a reaction temperature of 40 °C. The models pertinent to the sorption data were those based on the Langmuir adsorption isotherm and pseudo-second-order kinetics. Nitrate adsorption on Ce/Zr (1:3) bimetallic oxide was observed as spontaneous, feasible, and endothermic, according to the thermodynamics investigation. The activation energy value and E parameter of the Dubinin-Radushkevich model demonstrated that the sorption process was governed by a physical phenomenon. The findings from the mass transfer study imply that film diffusion and the particle diffusion mechanism work together in the present sorption process, but the former acts as a rate-limiting phase and controls the overall rate of the nitrate sorption process. The XPS investigation revealed the occurrence of bimetallic oxide-mediated reduction of the adsorbed nitrate into nitric oxide through the formation of nitrite as a transient intermediate. Column adsorption behaviour was also examined by using beads of the bimetallic oxide. The experimental outcome of the column study reveals that the beads possess a high affinity for capturing nitrate ions from an aqueous phase. A phytotoxicity investigation was also conducted to assess any potential adverse environmental effects of the produced bimetallic oxide. The regenerated bimetallic oxide was found to be proficiently recycled up to six successive nitrate removal operations with no substantial loss in the uptake efficacy.

Bio-sorptive remediation of crude oil polluted sea water using plantain (Musa parasidiaca) leaves as bio-based sorbent: Parametric optimization by Taguchi technique, equilibrium isotherm and kinetic modelling studies

This study investigated the potential of employing plantain leaves as a natural bio-based sorbent for crude oil spill polluted seawater remediation. Type L9(34) Taguchi orthogonal array technique was used to evaluate the effect of four independent bio-sorption factors at three different levels (crude oil initial concentration (X1 7.8, 11.5 and 15.6 g/L), seawater-crude oil temperature (X2 25, 35 and 45 °C), bio-sorbent dosage (X3 1, 2 and 3 g) and bio-sorbent particle size (X4 1.18, 2.36 and 4.72 mm) on two response indices (bio-sorption efficiency (%) and bio-sorption capacity (g/g)). Taguchi optimization technique, numerical-desirability index function optimization technique and a proposed optimization method were utilized to determine the optimum bio-sorption factors needed for the optimum bio-sorption efficiency and bio-sorption capacity. The results demonstrated that the crude oil bio-sorption efficiency of the plantain leaves was significantly influenced by X1, X3 and X4 and the bio-sorption capacity was mainly influenced by X1 and X3. The optimum bio-sorption efficiency and the optimum bio-sorption capacity were 99.05 % and 12.82 g/g, respectively, obtained at optimum combination of factors and levels of X11 (7.8 g/L), X33 (3 g) and X41 (1.18 mm) for bio-sorption efficiency and X13 (15.6 g/L) X31 (1 g) for bio-sorption capacity. The Freundlich and Dubinin-Rudeshkevich isotherm models best explain the equilibrium bio-sorption data, while the pseudo-second order kinetic model best describes the bio-sorption kinetics. The bio-sorptive remediation mechanism followed dual mechanism of physical and chemical bio-sorption and the mass transfer controlled by film diffusion. The maximum bio-sorption capacity (Kf) was 14.0 gg-1.

Crystal plasticity study of the effect of asymmetric structure of diffusive film cooling hole on heterogeneous creep and fracture behavior of NBSC superalloy

The heterogeneous creep and fracture behavior of nickel-based single crystal (NBSC) superalloys with inclined and diffusive holes are investigated. The analyses are made by creep experiments and crystal plasticity (CP) simulation with a modified creep constitutive model that accounts for both plastic and creep shear slip near the cooling hole. The study indicates that the cooling hole has a creep-strengthening effect on the NBSC superalloy, resulting in an extended creep duration for specimens with cooling holes than those without holes. Meanwhile, the asymmetric structure of diffusive and machined-tapered inclined cooling holes causes localized stress concentration around outlet side of the holes, which leads to asymmetric deformation and decreased rupture strain. Moreover, the interaction between neighboring holes causes shear slip and creep deformation more dominantly at side holes than at the center hole. Thus, preferential initiation of microcrack occurs around the side holes. The specimen without a hole displays typical ductile fracture, whereas the specimen with cooling holes displays a combined cleavage-like and ductile fracture due to the localized stress concentration induced by plastic shear slip around the hole. In addition, as loading stress increased, the creep lifetime and rupture strain decreased, while the characteristics of cleavage-like rupture increased.

Production of surfactant-modified banana peel biosorbents applied to treatment and decolorization of effluents

In this study, banana peels (BP) were pretreated under different conditions and modified with surfactants cetyltrimethylammonium bromide (CTAB), dodecyl trimethylammonium bromide (DTAB), or sodium dodecyl sulfate (SDS). The biosorbents were used for the removal of the anionic Direct Blue 86 (DB86) from synthetic solutions as well as for the treatment of a textile effluent. The biosorbents were characterized by Fourier Transform Infrared Spectroscopy (FTIR), contact angle measurements, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and point of zero charge (pHPZC). The results showed that the pretreatment using natural oxidation of BP showed better adsorbent performance than other pretreatments at pH 2. Treatment with SDS did not improve the sorption efficiency of the material. The biosorbents modified with DTAB (B-DTAB) and CTAB (B-CTAB) showed good performance with a maximum dye removal of 96.2% (at pH 2) and 91.7% (at pH 6), respectively, using 1.00 g L−1 of the biosorbents, constant stirring of 150 rpm for 60 min at 25 °C, and DB86 concentration of 10.0 mg L−1. The kinetics of B-DTAB and B-CTAB showed the best fit to the pseudo-first and pseudo-second-order models, respectively. The intraparticle diffusion model suggested that adsorption on B-CTAB may be guided by pore and film diffusion. Sips isotherm was found to be the best fit with theoretical maximum adsorption capacities from non-linear fit of 25.2 and 147 mg g−1, respectively, for B-DTAB and B-CTAB (1.00 g L−1 of the biosorbents, constant stirring of 150 rpm, 25 °C, and initial pH 6). Results suggest that mainly precipitation, hydrophobic interactions, and electrostatic attraction drives the sorption process. The treatment of the textile effluent using B-CTAB resulted in a reduction of 60.6% in color and 53.2% in effluent turbidity, demonstrating the potential of modified banana peels as promising biosorbents for environmental applications.

Removal of diclofenac from aqueous solution by chitosan-encapsulated Aliquat-336 capsules: Optimization of preparation conditions and adsorption mechanism

To enhance the effectiveness of ionic liquids in water treatment, a novel approach was devised involving the encapsulation of ionic liquids within a chitosan shell. This study focuses on the development and application of chitosan-encapsulated Aliquat-336 capsules (CACs) for the removal of diclofenac (DCF) from aqueous solution. The optimal preparation conditions, as determined through response surface methodology, were as follows: (1) Aliquat-336 content = 13.8%, (2) TPP concentration = 6%, and (3) crosslinking time = 0.5 h. CACs exhibited exceptional adsorption capabilities for DCF across a wide pH range, and the maximum adsorption capacity was 387.2 ± 25.6 mg/g at pH 7 according to the adsorption isotherm results. Adsorption kinetic results showed that the overall adsorption rate of DCF was controlled by liquid film diffusion. Furthermore, the slight antagonism of coexisting anions at low concentrations and significant synergy at high concentrations confirmed the practical suitability of CACs. The characterization of CACs before and after adsorption was analyzed by electron microscopy, pHPZC analysis, Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The results demonstrated the successful preparation of CACs and underscored the pivotal role played by the quaternary amine group within Aliquat-336, encapsulated within the CACs, in facilitating the removal of DCF through electrostatic attraction.

Biochar as a sustainable alternative for the use of residues from the processing of açaí and the removal of glyphosate

In this study, adsorbents produced from residues from the processing of açaí from the Amazon were acquired and impregnated or not with FeCl2 and FeCl3 to remove glyphosate present in the aqueous matrices. The effects of pH, adsorbent mass, glyphosate concentration, contact time and temperature on the adsorption capacity, kinetics, isothermal and thermodynamic parameters were studied via batch adsorption tests. The removal of glyphosate in the açaí seed biochar with Fe was higher than that in the açaí seed biochar, reaching a removal efficiency of 87.9% when using 20 mg L−1 glyphosate and 10 g L−1 adsorbent. The pH study demonstrated greater adsorption capacities at pH 4.0 (18.6 mg g−1). The pseudo-first-order model was the most appropriate to describe the adsorption kinetics. The Weber-Morris model showed that the adsorption occurred by film and intra-particle diffusion. Adsorption equilibrium isotherms were better fitted to the Langmuir model (qm= 351.4 mg g−1). Thermodynamic data demonstrated that the process was spontaneous and favorable and that the adsorption was exothermic in nature. Because they have magnetic characteristics, açaí seed biochar with Fe can be easily separated and reused. Therefore, depending on the adsorption capacity of the adsorbent with iron and the adsorption efficiencies demonstrated in this study, it is concluded that the adsorbent can be used as an intermediate in the processes of removing glyphosate present in aqueous matrices.

Chromium Disarmament from Veritable Tanneries Sewer Water Utilizing Carbonic Rice Straw as a Sorbent: Optimization and Carbonic Rice Straw Characteristics

This exploration focuses on the removal of chromium from actual tannery wastewater, collected from the HARBY TANNERY factory in Rubiki (Badr City), using an economical sorbent made from activated carbon derived from rice straw (CRS). The CRS sorbent is activated using H3PO4. The experiment aims to assess the impact of various parameters, including chromium initial concentration, sorbent dosage, treatment time, agitation velocity (rpm), sorbent particle size, and solution pH, on chromium removal from tannery wastewater. Structural, morphological, and electronic distinctive of raw and treated CRS, as well as carbonized CRS, were analyzed using FTIR, SEM, and TEM techniques. XRF analysis was conducted to investigate the chemical elemental composition of carbonized CRS before and after sorption. Zeta potential measurement was performed to assess the electrical charges of particles present in a suspension. The adsorption data was tested for both Langmuir and Freundlich adsorption isotherms, and most of the factors suggested that it follows the Langmuir adsorption isotherm with an R2 value of 99.67%. Additionally, adsorption kinetics were performed to identify the reaction order, which exhibited that sorption pursued pseudo-second-order kinetics with a rate constant (k) of 0.0658 g/mg g/min, a high correlation factor (R2) of 99.76%, and an estimated equilibrium chromium ion adsorption capacity (qe) of 1.597 mg/g, which closely matched the experimental data (1.4835 mg/g). The improved surface morphology and increased surface area of CRS resulted in approximately 98.9% chromium removal. Mechanism studies confirmed that intraparticle diffusion is not the sole rate-controlling step, and Boyd’s model demonstrated that film diffusion limited the rate of chromium adsorption. The desorption of chromium from the carbonized rice straw surface could be achieved by up to 96.4% of the sorbed amount by raising the solution pH to 10, indicating the potential reusability of carbonized rice straw for additional adsorption cycles. Finally, a statistical regression analysis and least square multivariate analysis were used to establish a correlation for predicting efficiency, yielding an R2 value of 97.54%.

Performance and mechanisms of active attapulgite-supported sulfidated nanoscale zero-valent iron materials for Pb(II) removal from aqueous solution

To inhibit the oxidation, passivation, and agglomeration of nano-zero-valent iron (nZVI), a liquid phase reduction method was used to load sulfurized nZVI onto acid-modified ATP with attapulgite (ATP) as the carrier (S-nZVI@ATP). The performance and mechanism of this material were studied for Pb2+ removal in water. The S-nZVI@ATP preparation prevents the agglomeration of nZVI particles and reduces nZVI oxidation. Pb2+ removal proceeds efficiently and stably when using S-nZVI@ATP at pH values ranging from 2.5–5.5. According to the electron sharing and transfer-based pseudo-second-order kinetic model, the Pb2+ is adsorbed onto S-nZVI@ATP, and the speed control step is completed by liquid film diffusion and intraparticle diffusion. The S-nZVI@ATP mediated Pb2+ adsorption is well-described by Freundlich’s isothermal adsorption model, which is a multilayer chemical adsorption process. The temperature and initial Pb2+ concentration were varied, and it was determined that Pb2+ adsorbs on S-nZVI@ATP in an endothermic reaction. This S-nZVI@ATP composite material has high reducibility, high surface activity, and good adsorption properties for Pb2+. Tests were performed for 24 h using adsorbent (1 g l−1) in Pb2+ solution (30 ml). For an initial Pb2+ concentration of 700 mg l−1, S−1-nZVI@ATP removes 57.37% of the Pb2+ and has an adsorption capacity of 401.60 mg g−1. In addition to forming PbS and Pb(OH)2 precipitates, Pb2+ also complexes with the Fe/H oxide shell of S-nZVI@ATP, and Fe0 reduces some Pb2+ on the nZVI to Pb0. The results exhibited that S-nZVI@ATP has excellent potential as an adsorbent for the removal of Pb2+ from the industrial wastewater.

Diaminopropane-appended activated carbons for the adsorptive removal of gaseous formaldehyde using a portable indoor air purification unit

It is of significant practical interest to develop high-performance air purifier (AP) for removing carcinogenic volatile organic compounds present ubiquitously in indoor air (e.g., formaldehyde (FA)). In this regard, a portable AP system was designed by loading honeycomb ceramic filters with diaminopropane (DAP)-appended activated carbon (AC). The maximum removal efficiencies (REs) of AP loaded with 10, 20, 30, and 50 %-DAP/AC were 26.2, 28, 88.3, and 89.4 %, respectively, against 5 ppm FA (at 160 L min−1). Hence, the 30 % DAP unit was used mainly in this work. The removal efficiency of 30 %-DAP/AC (160 L min−1), when tested against 2 ppm FA, decreased from 90.3 to 73.2 % with an increase in relative humidity from 0 to 60 %. The performance of the AP unit, when assessed kinetically in terms of the clean air delivery rate (CADR), reached as high as 10.2 L min−1 at the flow rate of 160 L min−1. Isotherm analysis further demonstrated the complex multilayered adsorption behavior of FA. Based on the density functional theory (DFT) simulation, the superiority of DAP/AC for FA adsorption can be attributed to the synergy of covalent (chemisorption) and non-covalent (pore filling and film diffusion) interactions.

Modeling of CO2 Adsorption on Surface-Functionalized Rubber-Seed Shell Activated Carbon: Isotherm and Kinetic Analysis

Currently, adsorption is considered a promising technology for CO2 separation with a wide range of adsorbents. A detailed study of equilibrium and kinetics plays a crucial role in the design and operation of industrial adsorption units. In this study, isotherm and kinetics of CO2 adsorption on two RSS-derived AC samples previously prepared in our laboratory were evaluated using equilibrium experiments for pure CO2 at 25 °C and 40 °C and 1 bar. Blank and IL-functionalized AC showed CO2 adsorption capacity of 2.16 mmol/g, 1.96 mmol/g, 1.12 mmol/g and 1.71 mmol/g at 25 °C and 40 °C, respectively. Langmuir, Freundlich, and Temkin equations were used to model adsorption isotherm in low-pressure regions. The obtained results revealed that the Freundlich model provides an accurate fitting to the experimental findings, which indicate that the adsorption process occurs in a heterogeneous phase. Additionally, kinetic analysis was performed by using four empirical models, namely pseudo-first order, pseudo-second order, Elovich, and Avrami’s fractional models. Among the considered kinetic models, the pseudo-second order model fits best for both blank and IL-functionalized AC. Intra-particle and Boyd’s film diffusion models were evaluated for the adsorption mechanism.

Thermal, Mechanical, and Electrical Stability of Cu Films in an Integration Process with Photosensitive Polyimide (PSPI) Films.

Photosensitive polyimides (PSPIs) have been widely developed in microelectronics, which is due to their excellent thermal properties and reasonable dielectric properties and can be directly patterned to simplify the processing steps. In this study, 3 μm~7 μm thick PSPI films were deposited on different substrates, including Si, 50 nm SiN, 50 nm SiO2, 100 nm Cu, and 100 nm Al, for the optimization of the process of integration with Cu films. In situ temperature-dependent resistance measurements were conducted by using a four-point probe system to study the changes in resistance of the 70 nm thick Cu films on different dielectrics with thick diffusion films of 30 nm Mn, Co, and W films in a N2 ambient. The lowest possible change in thickness due to annealing at the higher temperature ranges of 325 °C to 375 °C is displayed, which suggests the high stability of PSPI. The PSPI films show good adhesion with each Cu diffusion barrier up to 350 °C, and we believe that this will be helpful for new packaging applications, such as a 3D IC with a Cu interconnect.

Thermal Fatigue Effect on the Grain Groove Profile in the Case of Diffusion in Thin Polycrystalline Films of Power Electronic Devices.

In a previous paper, we solved the partial differential equation of Mullins' problem in the case of the evaporation-condensation in electronic devices and gave an exact solution relative to the geometric profile of the grain boundary grooving when materials are submitted to thermal and mechanical solicitation and fatigue effect. In this new research, new modelling of the grain groove profile was proposed and new analytical expressions of the groove profile, the derivative and the groove depth were obtained in the case of diffusion in thin polycrystalline films by the resolution of the fourth differential equation formulated by Mullins that supposed y'2≪1. The obtained analytical solution gave more accurate information on the geometric characteristics of the groove that were necessary to study the depth and the width of the groove. These new findings will open a new way to study with more accuracy the problem of the evaporation-condensation combined to the diffusion phenomenon on the material surfaces with the help of the analytical solutions.

In-situ synthesis of efficient ZnCl2 doped pyrolyzed biochar for adsorptive remediation of organic dyes: Performance evaluation, mass transfer and mechanism

Effective management of harmful contaminants from waste effluent is crucial for a sustainable environment. Herein, the efficient adsorbent, sawdust-derived biochar doped with ZnCl2 (Z@SB) for removal of organic dyes, namely malachite green (MG) and methyl orange (MO), was explored via batch adsorption study. A detailed characterization of the synthesized adsorbent was conducted to determine its physiochemical properties. The specific surface area of Z@SB from BET analysis improved 5.66 times after chemical modification. Moreover, the decolorization efficiency of the dyes onto Z@SB was investigated through analyzing the impact of initial pH, adsorbent dose, and contact time of the process. The Langmuir isotherm analysis revealed the maximum adsorption capacity (Qmax) of MG and MO dyes were 318.47 and 225.73 mg/g, respectively. The adsorption kinetics data of both dyes was well described by the pseudo-second-order model. Furthermore, Boyd's film diffusion model was employed to assess the diffusion mechanism and determine the rate-limiting step using the kinetic data obtained from batch adsorption experiment. Possible mechanisms for the removal of dyes onto Z@SB included hydrogen bonding, π-π bonding, and electrostatic interactions. The superior regeneration and reusability properties observed in Z@SB make it a highly promising adsorbent for effective utilization in real-field wastewater treatment applications.

Hydrogen diffusion in cerium oxide thin films fabricated by pulsed laser deposition

Cerium oxide (CeO2) is well known to be reducible by hydrogen (H2), yet the diffusion and solution properties of hydrogen in ceria at elevated temperatures have remained challenging to evaluate. We therefore fabricated nanometer-thin (∼100 nm) cerium oxide films on Si(111) substrates by pulsed laser deposition (PLD) and quantitatively investigated the H depth distributions therein by means of resonant 1H(15N,αγ)12C nuclear reaction analysis (NRA) before and after annealing in H2 gas at 773–973 K. X-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) reveal that the as-deposited films exhibit single phase CeO2 structure and partially reduced stoichiometry (CeO1.69). H2 annealing does not largely change the H content of the as-deposited films; in all conditions several atomic percent of hydroxyl (OH) are found to exist in a thin (∼4 nm) surface layer, whereas stably bound hydrogen in the bulk of the films is almost uniformly distributed and of much smaller quantity (∼0.2 at.%) than the oxygen vacancy concentration in the partially reduced ceria. Its low concentration and high thermal stability identify this bulk H species as likely being strongly bound to defects in the polycrystalline films rather than as a hydride species that interacts weakly with O-vacancies. The H diffusion coefficient and activation energy in the ceria films are determined as > 10−18 m2 s−1 at 773–973 K and <1.69 eV, respectively. The observed diffusion activation energy is somewhat larger than theoretical predictions for thermal diffusion of H in stoichiometric bulk CeO2, suggesting that defects and oxygen vacancies in the PLD-fabricated ceria thin films possibly have an impact on the H mobility.

Cypermethrin adsorption by Lactiplantibacillus plantarum and its behavior in a simulated fecal fermentation model.

The presence of cypermethrin in the environment and food poses a significant threat to human health. Lactic acid bacteria have shown promise as effective absorbents for xenobiotics and well behaved in wide range of applications. This study aimed to characterize the biosorption behavior of cypermethrin by Lactiplantibacillus plantarum RS60, focusing on cellular components, functional groups, kinetics, and isotherms. Results indicated that RS60 exopolysaccharides played a crucial role removing cypermethrin, with the cell wall and protoplast contributing 71.50% and 30.29% to the overall removal, respectively. Notably, peptidoglycans exhibited a high affinity for cypermethrin binding. The presence of various cellular surface groups including -OH, -NH, -CH3, -CH2, -CH, -P = O, and -CO was responsible for the efficient removal of pollutants. Additionally, the biosorption process demonstrated a good fit with pseudo-second-order and Langmuir-Freundlich isotherm. The biosorption of cypermethrin by L. plantarum RS60 involved complex chemical and physical interactions, as well as intraparticle diffusion and film diffusion. RS60 also effectively reduced cypermethrin residues in a fecal fermentation model, highlighting its potential in mitigating cypermethrin exposure in humans and animals. These findings provided valuable insights into the mechanisms underlying cypermethrin biosorption by lactic acid bacteria and supported the advancement of their application in environmental and health-related contexts. KEY POINTS: • Cypermethrin adsorption by L. plantarum was clarified. • Cell wall and protoplast showed cypermethrin binding ability. • L. plantarum can reduce cypermethrin in a fecal fermentation model.

Simultaneous Determination of Thermal Conductivity and Heat Capacity in Thin Films with Picosecond Transient Thermoreflectance and Picosecond Laser Flash

ABSTRACT Combining the picosecond transient thermoreflectance (ps-TTR) and picosecond laser flash (ps-LF) techniques, we have developed a novel method to simultaneously measure the thermal effusivity and the thermal diffusivity of metal thin films and determine the thermal conductivity () and the heat capacity () altogether. In order to validate our approach and evaluate the uncertainties, we analyzed five different metal films (Al, Cr, Ni, Pt, and Ti) with thicknesses ranging from 297 nm to 1.2 µm. Our results on thermal transport properties and heat capacity are consistent with reference values, with the uncertainties for the thermal conductivity and the heat capacity measurements below 25% and 15%, respectively. Compared with the ps-TTR technique alone, the combined approach substantially lowers the uncertainty of the thermal conductivity measurement. Uncertainty analyses on various materials show that this combined approach is capable of measuring most of the materials with a wide range of thicknesses, including those with low thermal conductivity (e.g., mica) down to thicknesses as small as 60 nm and ultrahigh thermal conductivity materials (such as cubic BAs) down to 1400 nm. Simultaneous measurement of thermal conductivity and heat capacity enables exploration of the thermal physical behavior of materials under various thermodynamic and mechanical perturbations, with potential applications in thermal management materials, solid-state phase transitions, and beyond.