Electrostatic Attractive Forces Research Articles

2-Amino-2-methyl-1-propanol regulated triethylenetetramine-based nonaqueous absorbents for solid-liquid phase-change CO2 capture: Formation of crystalline powder products and mechanism analysis

Solid-liquid phase-change absorbents (SLPCAs) have a great potential to reduce the energy consumption of CO2 capture. The main issue in the practical application of SLPCAs is the difficulty in the phase separation of gelatinous solid products. In this study, 2-amino-2-methyl-1-propanol (AMP) was used as a regulator to tune the physical form of the solid products of triethylenetetramine (TETA)-based SLPCAs. Experimental results showed that the AMP-regulated TETA-based SLPCAs successfully avoided the formation of gelatinous products (viscosity up to more than 1000 mPa·s) and yielded easily separated crystalline powders. Among the investigated SLPCAs, TETA/AMP/N-methyl-2-pyrrolidone (NMP) (TETA:AMP = 2:8, 1 M) exhibited the best CO2 capture performance with a high CO2 loading of 0.94 mol·mol−1 and a high regeneration efficiency of 84.14 %. XRD, FT-IR and 13C NMR analyses indicated that TETA/AMP/NMP absorbed CO2 to form highly polar carbamate species and protonated amines, which could break the original assimilation state of the SLPCA system; thus, the polar products precipitated out from less polar NMP, leading to a phase change. The theoretical calculations revealed that in the absence of AMP, the TETA-derived products had a tendency to form gelatinous aggregation with large amounts of hydrogen bonds; with the introduction of AMP, the AMP-derived products tended to combine with the TETA-derived products via strong electrostatic attraction and Van der Waals force and effectively inhibited the aggregation formation. Since there was only one hydrogen bond forming between the AMP- and TETA-derived product molecules, the amount of hydrogen bonds was significantly reduced. Eventually, the TETA/AMP/NMP SLPCA avoided the formation of gelatinous products and yielded crystalline powder products.

Designing polydopamine-capped [BMIm]PF6@halloysite/NaL microcapsule optimize the wear-resistance of polymer composite liner

Researchers have tried to encapsulate various lubricants with kinds of inorganic shell materials forming lubricant microcapsules. In this work, halloysite nanotubes (HNTs) have been employed as nanocontainers for loading ionic liquid (IL) of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIm]PF6). To improve the uptake of [BMIm]PF6, the lumen is functionalized with sodium laurate (NaL) by electrostatic attractive forces. Besides, a polydopamine (PDA) layer uses as end-stopper to prevent IL premature release. Finally, the obtained PDA-capped [BMIm]PF6 @halloysite/NaL microcapsules are incorporated into phenolic resin based PBO/PTFE textile composite liner. Results demonstrate that the wear rate decrease from 0.96 × 10−14 m3/(N•m) to 0.51 × 10−14 m3/(N•m) compared with pure composites owing to the robust tribofilm constructed on pin surface.

Adhesion effect and mechanism of siderophore-producing bacteria onto goethite and boron-doped goethite

This study aimed to elucidate the adhesion mechanism of siderophore-producing bacteria to goethite and boron-doped goethite. To meet the aims of the study, goethite and siderophore-producing bacteria were employed. The interaction between goethite and siderophore-producing bacteria was explored using batch adhesion experiment and DLVO theory. Results showed that the maximum adhesion amounts of P. sp. and P. chlororaphis on goethite and boron-doped goethite were 2039.39 and 1848.65, and 1566.64 and 1333.39 mg g−1, respectively, at 25 °C and pH 6. As solution pH increased, adhering amount of P. sp. and P. chlororaphis to goethite and boron-doped goethite was decreased. Electrostatic attraction force and chemical bond formation were the main mechanism of iron oxide interaction with bacteria. Boron incorporation reduced adhesion of P. sp. and P. chlororaphis to goethite surface. Results of this study may provide a theoretical basis for the utilization of siderophore-producing bacteria to transform iron elements in soil.

Mandarin Biochar-TETA (MBT) prepared from Citrus reticulata peels for adsorption of Acid Yellow 11 dye from water

Dehydration technique with 80% sulfuric acid was used to create a novel biochar from mandarin peel wastes followed by condensate with triethylenetetramine (TETA) to give Mandarin Biochar-TETA (MBT). BJH, BET, FTIR, SEM, DSC, TGA, and EDX studies were used to characterise the MBT. The capacity of the newly developed biochar to remove Acid Yellow 11 (AY11) dye from a water solution was studied. The pH of AY11 dye adsorption was found to be best at pH 1.5. Using 100 ppm AY11 dye as a beginning concentration and 1.75 g L–1 MBT dose, the greatest percent of AY11 dye removal by MBT was 97.83%. The MBT calculated maximum adsorption capacity (Qm) was 384.62 mg g–1. Langmuir (LIM), Freundlich (FIM), Tempkin (TIM), and Dubinin–Radushkevich (DRIM) isotherm models were applied to analyse the experimental data. Furthermore, the results of these isotherm models were investigated by various known error function equations. The MBT experimental data was best suited by the LIM. Pseudo-first-order (PFO), pseudo-second-order (PSO), Elovich kinetic model (EKM), intraparticle diffusion (IPD), and film diffusion (FD) models were used to calculate kinetic data. A PSO rate model with a high correlation (R2 > 0.990) was used to assess the adsorption rate. The main mechanism of the MBT adsorption method of the AY11 dye’s anions adsorption is the electrostatic attractive forces that arise with the increase of positively charged sites in an acidic medium. The obtained data suggest that the prepared MBT adsorbent has the potential to be an effective material to remove the AY11 dye from water and that it may be used repeatedly without losing its adsorption efficiency.

Facile and scalable synthesis of mesoporous composite materials from coal gasification fine slag for enhanced adsorption of malachite green

The recycling of the solid wastes produced in the industrial process and converting them into functional materials with unique structures are of great significance for the sustainable development of human society. In this study, a facile and scalable synthesis method was designed for the preparation of mesoporous composite materials from waste coal gasification fine slag using K2CO3 as a mild chemical additive to chemically recombine SiO2 and Al2O3. At a fine slag to K2CO3 mass ratio of 1:1, a mesoporous composite material (OMB-KB) mainly composed of faujasite-Na and amicite was obtained, which possessed a uniformly porous and loose structure with a specific surface area of 40.26 m2/g and the pore size range of 2–50 nm. Metals inherited from the raw slag and various chemical groups existed on the surface of OMB-KB, making the materials have unique surface chemical properties. OMB-KB exhibited ultra-high adsorption performance on malachite green (MG), and the adsorption capacity reached 7218.31 mg/g when 0.01 g of OMB-KB and 300 ml of MG solution with a concentration of 300 mg/L were used for the adsorption at 298K. The increase of pH was beneficial to the adsorption of cationic MG, and the removal efficiency reached an excellent state at pH ≥ 6. The good fitting of the pseudo-second-order kinetic model and the Freundlich isotherm model suggested that the adsorption process was dominated by chemisorption. The thermodynamic analysis showed that the adsorption of OMB-KB to MG was endothermic, entropy-increasing and entropy-controlled. The adsorption of MG by the material was realized through the exchange interactions between cations, as well as the electrostatic attraction and van der Waals forces between –OH groups and MG. Meanwhile, the oxygen-containing groups and π-electrons in the carbon layer could also adsorb MG molecules by electrostatic attraction.

Characterization of sulfonated raw coal products as enhanced adsorbents for toxic methyl parathion pesticide: Advanced equilibrium investigation and effect of acid concentration

Raw coal (R.C) was treated with different H2SO4 concentrations (75, 85, and 95 %) via sulfonation modification, and the sulfonated products (SC-75, SC-85, and SC-95, respectively) were used as adsorbents for the toxic methyl parathion (MPn) pesticide. The XRD investigation reflected increase in the amorphization degree with increasing the acid concentrations as well as the surface area (2.8 mmol/g (SC-75) and 8.4 mmol/g (SC-95)) and acid density value (6.4 m2/g (SC-75) and 26.4 m2/g (SC-95)). With increasing acid concentration, sulfonation increasingly functionalised coal with active oxygenated chemical groups (–COOH and –S3OH); this was reflected by MPn adsorption capacities at R.C, SC-75, SC-85, and SC-95 saturation states of 210.2, 321.4, 392.5, and 560 mg/g, respectively. The sulfonation and acid concentration effects were assessed considering steric and energetic mathematical parameters of the monolayer model with one energy site as an advanced isotherm model. The adsorption site densities of R.C, SC-75, SC-85, and SC-95 at 83.45, 120.4, 136.77, and 165.4 mg/g, respectively, demonstrated that sulfonation and high acid concentration provide additional active functional groups in the coal structure. Considering the steric n parameter, each active site on the SC-95 surface adsorbs approximately four MPn molecules, in contrast to three and two molecules on SC-85 and SC-75, respectively. Energetic assessment [Gaussian (˂8 kJ/mol) and adsorption (˂40 kJ/mol) energies] demonstrated MPn uptake of MPn by sulfonated coal samples via different processes such as electrostatic attractive forces, van der Waals forces, dipole bonding, π–π interactions, and hydrogen bonding. Thermodynamic functions demonstrated MPn uptake via endothermic and spontaneous reactions.

Cold-set oat protein isolate--gellan gum binary gels with various microstructures: Fabrication, characterization, formation mechanism, and controlled release properties

Cold-set oat protein isolate (OPI) and gellan gum (GG) binary gels with various microstructures was fabricated with different amounts glucono-δ-lactone (GDL) as a carrier to deliver bioactive compounds. OPI and GG formed gel-like mixture at pH 8 mainly via hydrophobic interactions with a binding constant (Ka) of 3.85 × 104 M−1, while the mixture showed highest storage modulus (G′) with 0.1% GG (w/w, based on the dry weight of protein). Novel binary gels fabricated with 7% OPI (w/v) and 0.1% GG (w/w) (OGG) were then developed through addition of various amounts of GDL. For the gels prepared with 1.5% and 4.0% GDL (w/w, based on the dry weight of protein, pH 7.1 and 6.3, respectively), heterogeneous network formed by co-aggregated OPI and GG with a small amount of small GG particles dispersed within large aqueous pores were fabricated mainly through hydrophobic interactions. For OGG-3 (9.0% GDL, w/w) and OGG-4 (20.0% GDL, w/w), the final pH was 5.1 and 4.1 that around or lower than OPI's isoelectric point, hydrogen bonding and electrostatic attractive forces were developed between two polymers since OPI contained neat or positive charges, resulting in a compact coupled OPI-GG network structure. Heterogeneous network with small GG particles dispersed in pores allowed OGG-2 (4.0% GDL, w/w) had comparable good gel hardness to the gel formed with 9.0% GDL (w/w, OGG-3) with coupled microstructure, whereas OGG-3 showed a better ability to restrict the swelling induced release of riboflavin in SGF, and allowed sustainable release of riboflavin in SIF. Therefore, OPI-GG binary gels with various microstructures prepared by simple acidification method at ambient temperature have great potential to be used as delivery systems for heat-sensitive bioactive compounds in food and non-food applications.

Nano/microplastics: Fragmentation, interaction with co-existing pollutants and their removal from wastewater using membrane processes

Nanoand microplastic (NP/MP) is one of the most challenging types of micropollutants, coming from either direct release or degradation of plastic items into ecosystems. NP/MP can adsorb hazardous pollutants (such as heavy metals and pharmaceutical compounds) and pathogens onto their surface that are consumed by humans, animals, and aquatic living organisms. This paper presents the interaction of NP/MP with other pollutants in the water environment and mechanisms involved to enable the ultimate fate of NP/MP as well as the effectiveness of metal-organic frame (MOF)-based membrane over conventional membrane processes for NP/MP removal. It is found that conventional membranes could remove MPs when their size is usually more than 1000 nm, but they are ineffective in removing NPs. These NPs have potentially greater health impacts due to their greater surface area. MOF-based membrane could effectively remove both NP and MP due to its large porous structure, high adsorption capacity, and low density. This paper also discusses some challenges associated with MOF-based membranes for NP/MP removal. Finally, we conclude a specific MOF-based ultrafiltration membrane (ED-MIL-101 (Cr)) that can potentially remove both negative and positive charged NP/MP from wastewater by electrostatic attraction and repulsion force with efficient water permeability.

Evaluation of the mechanisms of adsorption of microcystins and nodularin-R onto rice husk-based biochar

• Non-electrostatic and electrostatic interactions govern cyanotoxin adsorption onto RH. • Charge-neutral MC-RR displays high adsorption onto RH at different concentrations. • MC-LR and NOD-R at low concentrations experience attractive interactions with RH surface. • MCs with net negative charge and NOD-R show less adsorption onto RH than MC-RR. • Lateral electrostatic repulsions are more pronounced for MC-LA than for MC-LW and MC-LF. Adsorption mechanisms of individual and collective sorption of microcystins (MCs) and nodularin-R (NOD-R) onto heat-treated rice husk (RH) at neutral pH were evaluated. The functional groups on cyanotoxin standards and RH surface as well as their charge indicate that non-electrostatic and electrostatic interactions are present. Surface area and porosity of RH were determined indicating that MCs and NOD-R can be adsorbed in secondary micropores and mesopores of RH. Positively charged guanidinium ion in arginine-containing MCs and NOD-R created attractive electrostatic forces with the negatively charged RH surface (pH PZC ∼3.3). MCs and NOD-R experience electrostatic repulsion with the surface due to the presence of negatively charged carboxylate groups. MC-RR, even at significantly high toxin concentrations, could be removed by RH as it had a strong attraction to the surface due to two arginines and its neutral charge. Other congeners adsorbed on RH experienced lateral intermolecular repulsion and repulsion with molecules in solution. At low sorbate concentrations, MC-LR and NOD-R had electrostatic attraction to the RH surface and MC-LA, MC-LW, and MC-LF experienced electrostatic repulsion with the surface at all concentrations. Non-electrostatic forces govern the adsorption process of MC-LA, MC-LW, and MC-LF, and electrostatic forces are significant for the adsorption of MC-LR, MC-RR and NOD-R at low concentrations (1-100 ng/mL) as well as the adsorption of MC-RR at high concentrations (1000 ng/mL). The presence of 0.3 M NaCl increases the adsorption of MC-LA and MC-LF proving that those molecules undergo repulsive interactions with RH. The adsorption of MCs and NOD-R onto RH is pH dependent, and it appears to be improved at pH values < pH PZC . Overall, the adsorption of MCs and NOD-R onto RH biochar depends on congener concentration, structure, and charge, and can be modified through optimization of structural properties of RH sorbent and sorption conditions, such as ionic strength and pH.

A SOI Out-of-Plane Electrostatic MEMS Actuator Based on In-Plane Motion

This work describes a novel micromechanical structure capable of producing out-of-plane motion from in-plane forces generated by electrostatic microelectromechanical system (MEMS) actuators. The MEMS actuator is fabricated in a commercial silicon-on-insulator (SOI) MEMS process and is anchored at two distinct locations through a pair of beams with a relatively low stiffness in the vertical direction. A comb-drive, whose fixed and moveable fingers are implemented in the same layer with a uniform thickness, is employed to create an attractive electrostatic force. This in-plane electrostatic force rotates the actuator along an axis defined by the anchors, which results in the vertical motion of a suspended platform. Due to the simple structure of the actuator, it can be readily manufactured with standard bulk micromachining processes. Experimental results demonstrate that the actuator can provide <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.02~\mu \text{m}$ </tex-math></inline-formula> of vertical displacement at a resonant frequency of 395 Hz when it is excited in air by a 10 V AC signal, while the displacement can be considerably increased in vacuum. It is further shown that the functionality of the actuator is not dependent on the type of excitation voltage; therefore, it can produce a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.09~\mu \text{m}$ </tex-math></inline-formula> static out-of-plane motion when excited by a 40 V DC voltage. A comprehensive comparison to the published works in the literature indicates that the proposed actuator is the only SOI electrostatic MEMS actuator with a relatively thick structural layer, i.e., <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10~\mu \text{m}$ </tex-math></inline-formula> , that can provide out-of-plane motion at low actuation voltage reported to date. [2022-0069]

Flocculation performance and mechanism of P (DMDAAC-AM) on clay mineral layer: Insights from DFT calculation and experiment

In order to investigate the flocculation performance and mechanism of quaternary ammonium cationic polyacrylamide (CPAM) on clay mineral particles. Dimethyl diallyl ammonium chloride (DMDAAC) and acrylamide (AM) were used as the monomers to synthesize the polymer P (DMDAAC-AM), referred to as PDA. The flocculation and sedimentation effects of PDA on the kaolinite and montmorillonite suspensions were studied. Furthermore, the PDA structural unit was constructed, and the adsorption mechanism on the kaolinite and montmorillonite layers was explored using the density functional theory calculation method. Experimental results reveal that PDA exerts a better flocculation and sedimentation effect than the commercially polyacrylamide (PAM) on kaolinite and montmorillonite suspensions, and the effect exerted by PDA on the kaolinite suspension is stronger than that on montmorillonite. Simulation results show that the PDA structural unit can be stably adsorbed on the surface of mineral particles: kaolinite (001¯) surface (−279.46 kJ/mol) > montmorillonite (001) surface (−226.09 kJ/mol) > kaolinite (001) surface (−220.76 kJ/mol). The difference in PDA adsorption on each surface is influenced by the various quantum chemical properties of the structural unit AM and DMDAAC molecules. During flocculation, PDA is adsorbed on the surface of the mineral particles exploiting hydrogen bonds and electrostatic attraction forces. During the adsorption process, electrostatic attraction plays the leading role. The polymer chains establish a bridge between the particles, and these bridging flocs settle down under the influence of gravity.

Multi-spectroscopic, molecular docking and molecular dynamic simulation evaluation of hydroxychloroquine sulfate interaction with caseins and whey proteins

This study investigated the interaction between hydroxychloroquine sulfate (HCQ) and caseins (CAS) or whey proteins (WP) by the means of various spectroscopic, molecular docking, and molecular dynamic (MD) simulation. The fluorescence spectrum revealed that CAS and WP interaction with HCQ resulted in static quenching due to the formation of HCQ-CAS and HCQ-WP complexes. The formation of complexes was also validated by fourier transform infrared spectroscopy (FTIR), circular dichroism spectroscopy (CD), X-ray diffraction (XRD), and scanning electron microscope (SEM). The FTIR and CD data revealed that HCQ binding altered the secondary structure of CAS and WP. Moreover, molecular docking and MD simulation were performed to analyze the formation of complexes, which compacted the CAS structure. Moreover, they also demonstrated that HCQ interaction with CAS and WP mainly involved hydrophobic interactions, with some hydrogen bonding and electrostatic attraction forces. This was consistent with the zeta potential, thermodynamic and FTIR analyses. In conclusion, the present study guides the construction of the CAS and WP as a drug delivery system for HCQ and helps us understand how HCQ interacts with food components such as milk proteins.

Electrolyte adsorption in graphene and hexagonal boron nitride nanochannels

Understanding the dynamics of confined electrolytes through graphene-based channels is essential in multiple fields of science including: (a) developing novel artificial membranes for drug delivery, DNA sequencing and water desalination and (b) developing quantum nanoelectronic devices. In this work, All-Atom molecular dynamics simulations are used to study the adsorption of confined NaCl electrolyte solutions in graphene (GR), hexagonal boron nitride (hBN) and combined GR-hBN-GR nano-channels over a wide range of electrolyte concentrations c∈(0.1,2) M. The behavior of electrolytes confined between these surfaces is analyzed by evaluating the ionic density profiles, Potential of Mean Force (PMF), net charge density and integrated charge. Although neither graphene nor hBN has net electric charge, we observed significant changes in the ionic structure including the enhanced accumulation of sodium and the depletion in chloride density close to the hBN interfaces at low salt concentration. However, increasing the salt concentration leads to accumulation of chloride close to hBN surfaces. Two different types of hBN-GR junctions are considered in this study: a) shuffle (zigzag bonds) and (b) glide (parallel bonds). High adsorption of sodium and chloride ions near shuffle GR-hBN-GR surfaces is observed due to electrostatic attraction forces between the sodium and nitrogen atoms and between chloride and boron atoms at hBN–graphene junctions across zigzag bonds. This study reveals that GR-hBN-GR with shuffle interface is highly advantageous in adsorbing sodium and chloride ions than graphene and hBN alone. To the best of our knowledge, this is the first study that elucidates the interaction between monovalent electrolytes and GR-hBN-GR heterostructures in a confined medium.

Mo-activated VC as effective cocatalyst for an enhanced photocatalytic hydrogen evolution activity of CdS

Seeking an efficient and stable cocatalyst is of importance for semiconductor-based photocatalytic water splitting to produce hydrogen. In this sense, Mo-activation of VC for better cocatalytic properties was proposed for the first time, aiming to attain improved hydrogen generation of CdS. Our novel, yet facile physical preparation method permits intimate coupling of Mo-activated VC cocatalyst to CdS (through electrostatic attraction force), thereby promises drastic activity enhancement for hydrogen generation. Results indicate the best VC-activating competency of Mo against other transition metals (Co, Fe, Ni, Zn and Cu), which induces highest H2 productivity of CdS after modifying with Mo-activated VC. Under optimum setting, CdS/Mo(0.38)-VC(5 wt%) manifested highest photocatalytic hydrogen production rate of 2267 μmol h−1 g−1, associated to 300 % and 440 % improvement as compared to that of CdS/VC(5 wt%) and pure CdS, respectively. Such activity also outperformed those that yielded by MoSx- or noble metals(Pt, Au or Ag)-co-catalyzed CdS, attributed to the promoted interfacial charges transfer and lowered overpotential of CdS/Mo(0.38)-VC(5 wt%) in hydrogen generation. Correspondingly, high apparent hydrogen production quantum efficiency of 4.3 % was also recorded by the same photocatalyst at 420 nm. In term of stability test, CdS/Mo(0.38)-VC(5 wt%) manifested excellent longevity in 24 h continuous photoreaction and fair recyclability over five consecutive photoreaction cycles. This work provides a new insight to cocatalysts design and synthesis, thereby realizing economic alternatives to precious metal (Pt, Au, Ag) in solar-derived H2 production.

Removal of hexavalent chromium via biochar-based adsorbents: State-of-the-art, challenges, and future perspectives

Chromium originates from geogenic and extensive anthropogenic activities and significantly impacts natural ecosystems and human health. Various methods have been applied to remove hexavalent chromium (Cr(VI)) from aquatic environmental matrices, including adsorption via different adsorbents, which is considered to be the most common and low-cost approach. Biochar materials have been recognized as renewable carbon sorbents, pyrolyzed from various biomass at different temperatures under limited/no oxygen conditions for heavy metals remediation. This review summarizes the sources, chemical speciation & toxicity of Cr(VI) ions, and raw and modified biochar applications for Cr(VI) remediation from various contaminated matrices. Mechanistic understanding of Cr(VI) adsorption using different biochar-based materials through batch and saturated column adsorption experiments is documented. Electrostatic interaction and ion exchange dominate the Cr(VI) adsorption onto the biochar materials in acidic pH media. Cr(VI) ions tend to break down as HCrO4-, CrO42-, and Cr2O72- ions in aqueous solutions. At low pH (∼1-4), the availability of HCrO4- ions attributes the electrostatic forces of attraction due to the available functional groups such as -NH4+, -COOH, and -OH2+, which encourages higher adsorption of Cr(VI). Equilibrium isotherm, kinetic, and thermodynamic models help to understand Cr(VI)-biochar interactions and their adsorption mechanism. The adsorption studies of Cr(VI) are summarized through the fixed-bed saturated column experiments and Cr-contaminated real groundwater analysis using biochar-based sorbents for practical applicability. This review highlights the significant challenges in biochar-based material applications as green, renewable, and cost-effective adsorbents for the remediation of Cr(VI). Further recommendations and future scope for the implications of advanced novel biochar materials for Cr(VI) removal and other heavy metals are elegantly discussed.

Effect ofGOagglomeration on the mechanical properties of graphene oxide and nylon 66 composites and micromechanical analysis

AbstractNanoparticles are prone to aggregation in the matrix under the action of surface energy, chemical bonding, electrostatic attraction, and van der Waals forces. Based on the molecular dynamics method, the tensile properties of graphene oxide (GO)‐reinforced nylon 66 composites were simulated and calculated, and the stress–strain curves, atomic stress clouds, and changes in the number of hydrogen bonds were obtained for the composites under tensile loading, and the effects of GO agglomeration on the mechanical properties of GO/PA66 composites were analyzed. When the GO mass fraction accounted for 90.3%, 80.5%, and 70.6% of the model, respectively, the mechanical properties of the composites decreased by 15.4%, 4.5%, and 4.2%, respectively. Because GO agglomeration in the composites made it difficult to bond effectively between GO and PA66, the number of hydrogen bonds and the type of hydrogen bonds within the model, varied with the degree of aggregation. The changes in the number of hydrogen bonds and the type of hydrogen bonds during uniaxial stretching were simulated by molecular dynamics. The number of hydrogen bonds and the type of hydrogen bonds directly affect the mechanical properties of the composites. It can be seen from the atomic stress cloud diagram that the aggregation of GO makes the mechanical properties of GO fail to exert effectively. The main stress is on the C atoms in the outermost layer of GO, while the stress on the inner layer C atoms is relatively small. As the degree of GO agglomeration decreases, the stress on each C atom of GO lamellae tends to be uniform, which effectively brings into play the excellent mechanical properties of GO and improves the mechanical properties of the composite.

Effect of slurry particles on PVA brush contamination during post-CMP cleaning

PVA (polyvinyl acetal) brush scrubbing is a widely used post-CMP cleaning process due to its low cost and high cleaning efficiency. However, during these processes, the PVA brush gets contaminated with abrasive particles that result in wafer cross-contamination and reduced cleaning efficiency. This study investigated the effects of abrasive types such as silica and ceria, the slurry pH, and the scrubbing process parameters on brush contamination. Ceria slurries showed significantly more contamination of brushes compared to silica slurries. The brush contamination increased with a decrease in pH from 7 to 4 due to increased electrostatic attractive forces between the ceria particles and the brush surfaces, although very low brush contamination was observed by the ceria slurries at pH 10 due to a strong electrostatic repulsion. Conversely, very low brush contamination was observed for the silica slurries at all pH values due to the reduced interaction between the particles and the brush surface (electrostatic repulsion). Furthermore, there was no significant effect of gap distance and brush rotation speed on brush contamination. The abrasive concentration and the contamination process time showed a linear relationship as the contamination was significantly increased by increasing the abrasive concentration in slurry and process time. These results indicate that brush contamination is more sensitive to the abrasive nature and concentration, the slurry pH, and the process time than to other parameters.

Hierarchical self-assembly of 0D/2D β-Bi2O3 crossandra flower morphology exhibits excellent photocatalytic activity against bromophenol dyes

Crossandra flower shape morphology of β-Bi2O3 nanoflakes was achieved successfully by the solvothermal method. Synthesized β-Bi2O3 nanoflakes were characterized using various characterization techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectra, Ultraviolet–Visible diffuse reflectance spectroscopy (UV-DRS), X-ray photoelectron spectrometer (XPS), N2 adsorption-desorption isotherms (BET), liquid chromatography with mass spectrometry LCMS, Dynamic light scattering (DLS) and Zeta potential (ZP). Moreover, thermal stability and phase change were studied using thermogravimetric analyzer (TGA) and differential thermal analyzer (DTA). The size, shape, and extent of growth was studied using transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX), and field emission scanning electron microscopy (FESEM). The crossandra flower shape morphology was achieved due to the effect of temperature (350 °C); this was due to the uniform shifting of heat throughout the material during calcination, which allows material growth along the c-axis. The obtained material was partially in de-agglomerated and agglomerated form, and agglomeration was due to electrostatic forces of attraction. Besides this, the synthesized β-Bi2O3 was utilized to investigate photocatalytic activity for the degradation of bromophenol blue (BPB) and bromocresol purple (BCP). β-Bi2O3 shows the effective catalytic activity as it degrades the phenolic dyes effectively. The degradation was 96% (160 min) and 94% (200 min) for BPB and BCP, respectively. Overall, β-Bi2O3 nanoflakes were more responsive as a photocatalyst for BPB, which took minimal time as compared to BCP.

Efficient and sustainable electro-sorption of rare earth by laser-induced graphene film

Due to the outstanding optical, electrical and magnetic properties, rare earth (RE) elements have been extensively utilized in many high tech fields. The efficient and sustainable recovery of RE has become an important challenge. In this study, a laser-induced graphene (LIG) film was used as an electrode to study the recovery of La, Nd and Ce by electro-sorption. The conductivity and pH value were affected by the applied current, voltage and RE initial concentration. Under the influence of both electrostatic attraction and electric force, interesting results show that the desorption capacities of La, Nd, and Ce ions reach up to 2510.5 mg g−1, 2349.25 mg g−1 and 2150.75 mg g−1, respectively, which are much higher than the common adsorption materials based on physical adsorption. The RE precipitates obtained by electro-sorption are La(OH)3, Nd(OH)3 and CeO2, respectively. The above investigation shows that a LIG film, used as an electrode, can promote the recovery of La, Nd, and Ce ions from an aqueous solution by an electro-sorption technique. Unlike common RE recovery methods, this study does not involve the environmental problems from hazardous chemicals.

The Effect of Electrostatic Force between the Nanoparticles and the Substrate on the Uniform Assembly of Inkjet-Printed Nanoparticles

Inkjet-printed functional nanoparticles are actively used in various engineering applications, including bioelectronic and chemical sensors. To maximize the functionalities of the nanoparticles, the printed nanoparticles must be uniformly assembled within the printed micro patterns. However, controlling the movement of the nanoparticles is challenging as it involves multiple mechanisms that play important roles. In this work, we propose an experimental methodology to independently vary the surface charge polarities of the nanoparticles and the printing substrates. We used this method to study the effect of the electrostatic forces between the nanoparticles and the substrate on the uniform assembly of the inkjet-printed nanoparticles during the drying of the inks. We confirmed that the attractive electrostatic force between the two is crucial in uniformly distributing the nanoparticles.