Charge Attraction Research Articles

Adsorption and removal of herbicide paraquat from aqueous solutions via novel bimetal organic framework: Kinetics, equilibrium and statistical surface modeling

This study examines the adsorption and removal of the herbicide paraquat in relation to a bimetal organic framework known as the Terbium/Palladium Metal-Organic Framework (Tb/Pd-MOF). Analysis of N2 adsorption/desorption isotherms, which were used to assess the properties of the Tb/Pd-MOF, revealed that the absorption of paraquat on Tb/Pd-MOF resulted in a reduction in pore volume, pore size, and surface area. Specifically, the pore volume decreased from 8.25 to 5.68 cm3/g, the pore size decreased from 11.34 nm to 8.92 nm, and the surface area decreased from 1456.61 to 1262.82 m2/g. The pore radius also decreased from 0.96 nm to 0.58 nm. Tb/Pd-MOF’s functional groups were identified through FT-IR, and the structure of the compound was confirmed using XPS. Various adsorption parameters including temperature, adsorbent dosage, pH, paraquat concentration, and contact time were studied. Density functional theory (DFT) was used to understand the electrical properties, reactivity, and morphology of paraquat. Results from the DFT analysis revealed that the electrophilic and nucleophilic attack sites aligned with the molecular orbitals (HOMO and LUMO) and MEP outcomes. The study found that Tb/Pd-MOF demonstrated a significant absorption capacity for paraquat, with adsorption data consistent with the Langmuir isotherm and pseudo-second-order kinetic models. The paraquat adsorption capability of Tb/Pd-MOF was determined to be 574.8 mg/g. Furthermore, chemisorption was identified as the primary form of adsorption, as indicated by the adsorption energy of 26.98 kJ·mol−1. The optimal conditions for achieving a high adsorption capacity were identified as pH 8 and 0.02 g of Tb/Pd-MOF. The temperature-dependent changes in the thermodynamic parameters ΔG°, ΔH°, and ΔS° indicated that the paraquat absorption onto Tb/Pd-MOF occurred spontaneously, was endothermic, and involved random processes. To optimize the absorption process, Response Surface Methodology and Box-Behnken design (RSM, BBD) were employed. These techniques enabled effective removal of paraquat from the Tb/Pd-MOF material. During chemisorption, the adsorbate and adsorbent form chemical bonds, while aromatic rings are involved in π-π bonding. Additionally, pore-filling occurs when the adsorbate fills the pores of the adsorbent, and electrostatic interactions result from the attraction or repulsion of charges between the adsorbate and adsorbent. As a means of eliminating paraquat from wastewater, Tb/Pd-MOF demonstrates significant potential due to its diverse absorption processes and high capacity for adsorption.

Template-directed strategy synthesis of CoNi-layered double hydroxide nanosheet coated with polypyrrole for enhanced capacitive deionization

Recently, faradic material layered double hydroxide (LDH) has been widely used as an anode for capacitive desalination (CDI), due to its reversible ion insertion/deintercalation process and high anion storage capacity. Unfortunately, the issues of poor conductivity and self-stacking of LDH limit its application in the CDI. Herein, CoNi-LDH coated with polypyrrole (PPy) was meticulously designed and synthesized PPy@CoNi-LDH nanohybrids using ZIF-67 as the precursor by template-directed strategy and in-situ polymerization. The CoNi-LDH has large interlayer distance of 0.91 nm, which is beneficial for ion insertion. Introduced PPy conductive layer improved the interface transfer rate of charges and increased the ion storage capacity of composite. The experimental test results indicate that PPy@CoNi-LDH1:1 electrode has a higher specific capacitance of 223.1F g−1 and lower resistivity of 62.33 Ω·cm compared to CoNi-LDH electrode (35.2F g−1 and 3.39 × 104 Ω·cm). Obtained PPy@CoNi-LDH1:1 also has abundant mesoporous and excellent hydrophilicity, which can promote ions transfer. Meanwhile, the specific surface area of PPy@CoNi-LDH1:1 with the coating structure is 1.78 times that of CoNi-LDH, effectively suppressing the self-stacking of CoNi-LDH and exposing more active sites. When employed PPy@CoNi-LDH1:1 as an anode and the activated carbon as a cathode, the PPy@CoNi-LDH1:1//AC cell exhibited a high Cl− removal capacity (60.20 mg g−1), a swift Cl− removal rate (11.45 mg g−1 min−1) and good cycling stability (the retention rate is 89.67 % after 50 cycles) in NaCl solution of 500 mg L−1 and 1.4 V applied voltage. Additionally, the adsorption mechanism indicated that surface charge attraction, ligand exchange, and ion insertion jointly promote the Cl− removal. This study provides a feasible solution about successful design of high adsorption capacity anode materials for CDI.

Functionalized expanded graphite foam supported by PVDF skeleton for cationic dyes selectively separating and purifying

In order to fully utilize the advantages of expandable graphite (large specific surface area and porous structure), a solvent-free method was used to provide a supporting skeleton for expandable graphite through melting, bonding and solidification of polyvinylidene fluoride (PVDF). Based on its porous structure and enhanced mechanical stability, the formed PVDF/expandable graphite composite foam, amounts of functional groups were introduced throughout the foam (outside on the surface and inner side in the expandable graphite) by deposition of tannic acid (TA) and dopamine (DA), endowing it selective adsorption characteristics. The functioned foam exhibited excellent dynamic dye adsorption capacity by capturing dye molecules firmly through π-π interaction, hydrogen bonding, and charge attraction between the functional groups and dyes. Furthermore, with low zeta potential (-24.9 mV), the functional groups showed selective adsorption properties resulting in rapid separation of cationic dyes and anionic dyes. The functionalized PVDF/expandable graphite composite foam contact these two materials together in order to complement each other's advantages, showing a new research orientation for the treatment of different types of dyestuff wastewater.

One-Step-Modified Biochar by Natural Anatase for Eco-Friendly Cr (VI) Removal

The global serious pollution situation urgently needs green, efficient, and sustainable development methods to achieve heavy metal pollution control. The photocatalytic properties of anatase are sufficient to achieve pollution control by providing photoelectrons to harmful heavy metals. However, since natural anatase particles tend to agglomerate and deactivate in water, most studies have been conducted to prepare TiO2–biochar nanocomposites using chemical synthesis methods. In the present study, we utilized pyrolytic sintering to load natural anatase onto biochar to obtain natural anatase–biochar (TBC) composites. Characterization tests, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), showed that anatase was uniformly partitioned into the surface and pores of biochar without destroying the lattice structure. Due to its photocatalytic properties, TBC degraded Cr (VI) by 99.63% under light conditions. This is 1.58 times higher than the dark condition. Zeta potential showed that the surface of the TBC was positively charged under acidic conditions. The charge attraction between TBC and chromium salt was involved in the efficient degradation of Cr (VI). Different sacrificial agents as well as gas purge experiments demonstrated that photoelectrons (e−) and superoxide radicals (O2−) dominated the degradation of Cr (VI). TBC has the characteristics of high efficiency, stability, and sustainability. This may provide a new idea for the preparation of photocatalytic materials and the realization of environmental protection and sustainable development through heavy metal pollution control.

Enhancing self-induced polarization of PVDF-based triboelectric film by P-doped g-C3N4 for ultrasensitive triboelectric pressure sensors

Progress in wearable energy devices has reached the point of popularity over a few decades, as reflected by the rise of numerous sensors and storage devices driven by the urgent need for Internet of Things (IoT) applications. Triboelectric sensor (TES), on the basis of triboelectric nanogenerators (TENGs), exhibits high sensitivity and stability for pressure detection. Maximizing the sensitivity of the TES hinges upon the triboelectric layer selection capable of harnessing triboelectrification and electrostatic induction. Among them, PVDF has gained attention owing to its exceptional flexibility and tribo-negativity. However, the multiphase of pristine PVDF poses challenges, limiting its potential for TES with higher sensitivity. Tackling this issue, herein, we introduced phosphorus-doped graphitic carbon nitride (PCN) into the PVDF films to achieve self-induced polarization to enhance the sensitivity of the triboelectric pressure sensor. Through a controlled annealing temperature, phosphorus atoms are incorporated into the g-C3N4 (CN) matrix, enhancing the electronegativity of PVDF/PCN composite film while inducing a polarized β crystal phase in PVDF, thereby enabling greater attraction of positive charges. Consequently, the triboelectric output with PVDF/PCN composite film exhibited a significant improvement compared to the pristine PVDF film, achieving over a 100 V increment and the ability to power more than 100 LEDs. Furthermore, for the pressure-sensing applications, the TES with flexible PVDF/PCN triboelectric film exhibits a pressure sensitivity of 1.48 V/kPa, which shows a threefold increase in sensitivity compared to the pristine PVDF film (0.51 V/kPa), suggesting their great potential in self-powered wearable pressure sensors.

Tetrasodium iminodisuccinate modified montmorillonite for Pb and Cd adsorption from water: Characterization and mechanism

Heavy metal pollution is a huge hazard to the water environment and modified clay adsorbents have been widely used to remove heavy metals from water. Degradable anionic chelating agents have a greater potential for the immobilization of heavy metals, so tetrasodium iminodisuccinate (IDS) was introduced to modify montmorillonite (Mt) for Pb(II) and Cd(II) adsorption from water in this study. IDS was bound with Mt by sonication, heating, and acidity to form IDS-Mt, and characterized by XRD, FT-IR, SEM, and zeta potential analyzer. The batch adsorption experiments revealed that IDS-Mt5 had excellent adsorption capacity of Pb(II) and Cd(II) up to 214.73 mg/L and 104.07 mg/L, respectively. The adsorption process of IDS-Mt on Pb(II) and Cd(II) was consistent with the Sips model and PSO model, indicating that the adsorption was heterogeneous and chemical. The adsorption capacities of IDS-Mt in the second cycle remained above 76 % for Pb(II) and 69 % for Cd(II) of the initial ones, respectively. IDS was immobilized on the interlayer and edge surfaces of Mt through interactions or forming hydrogen bonds facilitated by ultrasonic under acidic heating conditions. Pb(II) and Cd(II) were immobilized by IDS-Mt through cation exchange, negative charge attraction at the edge surface, and IDS chelation. IDS-Mt was an excellent adsorbent with strong dispersibility and swelling properties for Pb(II) and Cd(II) removal from contaminated water. This study provides a new solution for the anionic modification of Mt and a new material for the treatment of heavy metal wastewater.

Surface methodology for optimized adsorption of hazardous organic pollutant from aqueous solutions via novel magnetic metal organic framework: Kinetics, isotherm study, and DFT calculations

An efficient way to remove Janus Green B (JGB) dye from contaminated water sources is using of magnetic cerium (III) metal–organic framework (MCe-MOF). Analytical methods such as PXRD, TEM, FESEM, FT-IR, PZC, and XPS were used in the characterization of the MCe-MOF microspheres in order to assess the phase, crystallinity, shape, surface characteristics, and chemical composition of the MCe-MOF material. Impressive physical characteristics of the synthesized MCe-MOF material included a high surface area of 1340.05 m2/g. Conversely, MCe-MOF’s magnetic saturation (MS) was measured at 36.47 emu.g−1. The purpose of the study was to determine if MCe-MOF could effectively remove JGB dye from wastewater by adsorption. Adsorption settings that were studied included pH, adsorbent dose, beginning dye concentration, contact time, and temperature. The JGB electrical characteristics, reactivity, and shape were ascertained through the application of density functional theory (DFT). The placement of electrophilic and nucleophilic attack sites is in good agreement with the molecular orbitals (HOMO and LUMO) and MEP results, according to DFT. Based on the findings, MCe-MOF had a high capacity for adsorbing JGB dye, with an adsorption data fit by pseudo-second-order kinetic models and the Langmuir isotherm. It was evident from the adsorption energy of 27.8 kJ.mol−1 that chemisorption was the mode of adsorption. The optimal conditions for attaining a high adsorption capacity were found to be pH 8 and 0.02 g of MCe-MOF dose. The adsorption process of JGB dye onto MCe-MOF was seen to be spontaneous, endothermic, and random, as indicated by the temperature-dependent increases in the thermodynamic parameters ΔGo, ΔHo, and ΔSo. The adsorption process was optimized through the application of Response Surface Methodology and Box-Behnken design (RSM, BBD). The successful removal of dyes from the MCe-MOF material was made possible by these methods. While π-π bonding happens through the interaction of aromatic rings, chemisorption entails the formation of chemical interactions between the adsorbate and adsorbent. Electrostatic interactions arise from the attraction or repulsion of charges between the adsorbate and adsorbent, and pore-filling happens when the adsorbate fills the adsorbent’s pores. For the removal of JGB dye from wastewater, MCe-MOF exhibits great potential as an adsorbent because of its numerous adsorption processes and high adsorption capacity.

Flexible Surface-Enhanced Raman Scattering (SERS) sensor for residue-free pesticide detection based on agriculture 4.0 concepts

Given the health and environmental risks associated with pesticide misuse, achieving zero pesticide residues is pivotal in Agriculture 4.0. Traditional detection methods such as HPLC and GC-MS are both complex and time-consuming. In contrast, surface-enhanced Raman scattering (SERS) offers rapid detection and high sensitivity, aligning with the efficiency and accuracy requirements of Agriculture 4.0. In this study, we developed a high-performance flexible substrate using a simple chemical synthesis method. We used material adsorption, anisotropic charge attraction and electron migration to facilitate the growth of the substrate material, which promoted more 'hot spots' and electron transfer, and continued optimisation of the preparation process, which resulted in a significant increase in spectral intensity. The substrate demonstrated outstanding detection capability, with a detection limit of 10−15 M for thiabendazole (TBZ). In practical fruit testing, TBZ residue concentrations on the surface of American cherries could be detected as low as 10−8 mg/mL, well below China's prescribed limit of 5 mg/kg. Relative to previous work in the field of pesticide detection, our study has lower detection limits and concentrations, as well as lower cost and simpler preparation, which provide more options for the detection of very low concentrations of hazardous substances. At the same time, it was confirmed that SERS is consistent with the zero pesticide residue goal of Agriculture 4.0, demonstrating practical efficacy and accuracy within this framework.

Granular polyacrylonitrile with internal 3D channels for gold recovery from thiosulfate solution

Gold recovery technology is an urgent challenge in the industrialisation of thiosulfate-based gold extraction. Current materials used for gold recovery suffer from a lack of wear resistance and small particle size, which makes it difficult to separate the material from thiosulfate solutions. In this study, a cysteamine-functionalised granular polyacrylonitrile (cys-PANG) material containing three-dimensional channels was designed and synthesised. The results indicate that cys-PANG, prepared using a solvent exchange method, has remarkable adsorption capacity for gold, smooth outer surface, well-developed internal pore structure, high wear resistance, and controllable size, making it suitable for gold recovery from thiosulfate pulp. The adsorption of gold in a thiosulfate solution by cys-PANG followed the Freundlich isotherm and pseudo-second-order kinetic adsorption models with minimal pH dependence. Cys-PANG also demonstrated the effective adsorption of gold in a Cu(II)–ethanediamine (en)–S2O32− solution, even in the presence of copper and en interference. Both experimental results and theoretical calculations revealed that the interaction between cys-PANG and gold in the thiosulfate solution is predominantly characterised by charge attraction and ligand exchange mechanisms. Adsorption tests of cys-PANG in actual thiosulfate pulp demonstrated exceptional gold recovery properties and minimal wear even after 14 days of continuous stirring. This study presents a promising alternative methodology for the recovery of gold from thiosulfate pulp.

Efficient removal of amoxicillin and methyl orange with antibacterial activity assessment via nanostructured ZnO coatings synthesized by ultrasonic spray pyrolysis method

Our study explores the potential of ZnO nanostructured coatings synthesized through ultrasonic spray pyrolysis and focuses on the dual functionality of these coatings: efficiently removing amoxicillin and methyl orange, while also assessing their antibacterial activity. The characterization techniques used in this work include Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Photoluminescence spectroscopy (PL), X-ray Photoelectron Spectroscopy (XPS) and UV–visible spectroscopy. The degradation rates of amoxicillin and methyl orange were studied through the decrease in absorption bands at 228 nm and 436 nm, respectively, under UV irradiation. By closely analyzing the responses of Pseudomonas Aeruginosa, Bacillus Cereus and Bacillus Subtilis bacteria, zinc oxide thin films demonstrate antibacterial efficacy due to the attraction of opposite charges to the bacterial surface, which influences the oxidation process of the membrane, ultimately resulting in cellular death.

Droplet coalescence in coupled shear and electric fields: A molecular dynamics study

Water droplet coalescence in coupled flow and electric fields is a phenomenon extensively observed in petrochemical, microfluidic, and chemical synthesis processes; however, the existing research in this domain lacks the necessary depth. This paper employs a molecular dynamics approach to elucidate the microscopic mechanisms governing droplet aggregation in water-in-oil emulsions. The investigation spans various shear rates and droplet angles, considering droplet morphology and molecular interactions. The study reveals an interrelation between shear rate and droplet angle effects on droplet coalescence, both seeking to understand the impact of the flow field's shear effect on the electrocoalescence of water droplets. Increasing the shear rate proves advantageous to droplet aggregation up to a certain threshold; however, complete coalescence is hindered beyond the critical shear rate, γ = 7.5 × 109 s−1. Augmenting the droplet angle amplifies the shear force exerted by the flow field on the droplets, while diminishing the radial electric field force. Consequently, an optimal droplet angle of θ = 25° facilitates comprehensive droplet merging. The analysis of the coalescence process, interaction energy, charge density and radial distribution function shows that the approximate process of droplet motion is as follows: the shear effect drives the droplets to approach, and then the directional migration of charge and electrostatic attraction between water molecules drive the coalescence. The existence of a moderate shear effect enables complete droplet coalescence. This study offers theoretical guidance for the exploration of dynamic electrocoalescence technology.

Carbon nanoparticles neutralize carbon dioxide (CO2) in cytotoxicity: Potent carbon emission induced resistance to anticancer nanomedicine and antibiotics

Excessive carbon emissions, especially CO2 release, have been a global concern. Few studies applied nanotechnology to relieve the ecotoxicity of CO2. Here, we applied carbon dots (CDs) to neutralize the CO2. We found CO2 induced the aggregation of CDs, which is of significance for CDs in enhanced fluorescence intensity but decreased CDs function in nanozyme activity, and reduced CDs toxicity to bacteria and cancer cells. Our data suggest the concern of CO2 release in global health in CDs mediated anticancer drug delivery and antibiotics resistance. However, enhanced fluorescence in cells which can be applied for bioimaging or CO2 sensing as simulated investigation by static charged attraction of positively charged CDs with negatively charged soluble HCO3-. Thus, CO2 abrogates the nanomedicine efficacy in cancer cells and antibacterial and may induce drug resistance for patients undergoing chemotherapy or antibiotics therapy. To overcome the resistance, we may apply the CDs for a neutralization of CO2 for impact on anticancer nanomedicine and antibiotics and reducing the ecotoxicity in biological systems.

Unveiling the Role of Electrostatic Forces on Attraction between Opposing Polyelectrolyte Brushes.

Electrostatic interaction and molecular excluded-volume effects are responsible for a plethora of nonintuitive phenomena in soft-matter systems, including local charge inversion and attraction between similar charges. In the current work, we study the surface forces and swelling behavior of opposing polyelectrolyte brushes using a classical density functional theory that accounts for electrostatic and excluded-volume correlations. We observe that the detachment pressure between similarly charged brushes is sensitive to salt concentration in both the osmotic and salted regimes and can be negative in the presence of multivalent counterions. A comparison of the theoretical results with the mean-field predictions unravels the role of correlation effects in determining the surface forces and brush structure. For systems containing multivalent counterions, the detachment pressure attains negative values at an intermediate brush-brush separation, and the attractive region in the pressure vs distance plot is magnified in terms of both the depth and width of attraction with increasing counterion valency. However, the interbrush attraction vanishes when the size-induced correlations are switched off. We also investigated the role of counterion size and polymer chain length on the detachment pressure. It is found that smaller counterions are more effective in neutralizing the polymer charge than bigger counterions, leading to a reduced interbrush repulsion and, in some cases, attraction between like-charged brushes at intermediate distances. Meanwhile, varying the chain length of the grafted polymers only shifts the location of the attraction basin, with little influence on the interaction strength. The theoretical predictions show qualitative agreement with experimental observations and offer valuable insights into the interaction between similarly charged polymer brushes in the presence of multivalent ions.

Characteristics of Oil-in-Oil Emulsions under AC Electric Fields.

Emulsions have been applied in a number of industries such as pharmaceutics, cosmetics, and food, which are also of great scientific interest. Although aqueous emulsions are commonly used in our daily life, oil-in-oil (o/o) emulsions also play an irreplaceable role in view of their unique physics and complementary applications. In this paper, we investigate typical behaviors of organic droplets surrounded by organic medium (o/o emulsions) with different functional groups controlled by the AC electric field. Droplet behaviors can be catalogued into five types: namely, "no effect", "movement", "deformation", "interface rupture", and "disorder". We identify the key dimensionless number Wee·Ca, combined with the channel geometry, for characterizing the typical behaviors in silicon oil/1,6-hexanediol diacrylate and mineral oil/1,6-hexanediol diacrylate emulsions. Unlike aqueous emulsion, the Maxwell-Wagner relaxation inhibits the electric effect and leads to an effective frequency, ranging from 0.5 to 3 kHz. The increasing viscosity of the droplet facilitates the escalation by promoting the shearing effect under the same flow conditions. Ethylene glycol droplets primarily show the efficient coalescence even at a low Wee·Ca, which is attributed to the attraction of free charges induced by the increasing conductivity. In 1,6-hexanediol diacrylate/silicon oil emulsion, the droplet tends to form a liquid film that expands into the entire channel due to the affinity of the droplet to the channel wall. A variety of elongated columns are observed to oscillate between the electrodes at high voltages. These findings can contribute to understanding the electrohydrodynamic physics in o/o emulsion and controlling droplet behaviors in a fast response, programmable, and high-throughput way. We expect that this droplet manipulation technology can be widely adopted in a broad range of chemical synthesis and biological and material science.

Effective orientifolds from broken supersymmetry

We recently proposed a class of type IIB vacua that yield, at low energies, four–dimensional Minkowski spaces with broken supersymmetry and a constant string coupling. They are compactifications with an internal five-torus bearing a five–form flux Φ and warp factors depending on a single coordinate. The breaking of supersymmetry occurs when the internal space includes a finite interval. A probe-brane analysis revealed a gravitational repulsion and a charge attraction of equal magnitude from the left end of the interval, together with a singularity at the other end. Here we complete the analysis revealing the presence, at one end, of an effective of negative tension and positive five–form charge. We also determine the values of these quantities, showing that , and characterize the singularity present at the other end of the interval, which hosts an opposite charge. Finally, we discuss various forms of the gravity action in the presence of a boundary and identify a self–adjoint form for its fluctuations. Invited contribution to the special issue of Journal of Physics A: Mathematical and Theoretical on ‘Fields, Gravity, Strings and Beyond: In Memory of Stanley Deser’

(Invited) Unravelling the Core of Fuel Cell Performance: Engineering the Electrolyte (ionomer)/Catalyst Interface

The biggest challenge of the widespread implantation of the polymer electrolyte membrane fuel cells (PEMFCs) is the cost, primarily due to the use of platinum catalysts. The high intrinsic catalyst activity exhibited using a rotating disc electrode (RDE) is rarely realized in the membrane electrode assembly (MEA), which is the core of PEMFC, due to the difference on the electrolyte(ionomer)/catalyst interfaces. To translate the catalyst RDE performance into MEA, the design of an ideal ionomer/catalyst interface is proposed: a thin, conformal ionomer film covers the maximum surface of a Pt nanoparticle that simultaneously maximizes catalyst utilization, (i.e. high mass activity and electrochemical active surface area) and O2 diffusion (i.e. high current density performance) without compromising proton conduction. Building such an interface is a long-standing challenge due to no control of ionomer distribution over catalyst particle, resulting in large ionomer agglomerates and inhomogeneous ionomer coverage over the catalyst nanoparticle, consequently, poor fuel cell performance. In this work, this ionomer/catalyst interface has been constructed utilizing the electrostatic charge attraction between positively charged catalyst and negatively charged ionomer particles in a liquid and preserved into a solid catalyst layer. Consequently, this interface leads to the previously unachieved fuel cell performance on both the catalyst utilization (75% vs. 45%) and the rated/peak power density (Pt/C, 0.910/1.430 W/cm2 for H2/Air, Pt loading: 0.1 mgPt/cm2), matching that of Pt alloy catalysts. This work demonstrated the formation of the interface in the liquid phase (using ultra-small angle x-ray scattering in combination with cryo-TEM, isothermal‐titration‐calorimetry) and the preserved interface in the solid catalyst layer (using TEM) and estimated the effective coverage and thickness of the ionomer film (using the limiting current density, RDE and fuel cell performance).

Novel rod-like [Cu(phen)2(OAc)]·PF6 complex for high-performance visible-light-driven photocatalytic degradation of hazardous organic dyes: DFT approach, Hirshfeld and fingerprint plot analysis

A novel octahedral distorted coordination complex was formed from a copper transition metal with a bidentate ligand (1,10-Phenanthroline) and characterized by Ultraviolet–visible spectroscopy, Ultraviolet–visible diffuse reflectance spectroscopy, Fourier-transform infrared spectroscopy, Brunauer-Emmett-Teller, Field emission scanning electron microscopy, and Single-crystal X-ray diffraction. The Hirshfeld surface and fingerprint plot analyses were conducted to determine the interactions between atoms in the Cu(II) complex. DFT calculations showed that the central copper ion and its coordinated atoms have an octahedral geometry. The Molecular electrostatic potential (MEP) map indicated that the copper (II) complex is an electrophilic compound that can interact with negatively charged macromolecules. The HOMO-LUMO analysis demonstrated the π nature charge transfer from acetate to phenanthroline. The band gap of [Cu(phen)2(OAc)]·PF6 photocatalyst was estimated to be 2.88 eV, confirming that this complex is suitable for environmental remediation. The photocatalytic degradation of erythrosine, malachite green, methylene blue, and Eriochrome Black T as model organic pollutants using the prepared complex was investigated under visible light. The [Cu(phen)2(OAc)]·PF6 photocatalyst exhibited degradation 94.7, 90.1, 82.7, and 74.3 % of malachite green, methylene blue, erythrosine, and Eriochrome Black T, respectively, under visible illumination within 70 min. The results from the Langmuir-Hinshelwood kinetic analysis demonstrated that the Cu(II) complex has a higher efficiency for the degradation of cationic pollutants than the anionic ones. This was attributed to surface charge attraction between photocatalyst and cationic dyes promoting removal efficiency. The reusability test indicated that the photocatalyst could be utilized in seven consecutive photocatalytic degradation cycles with an insignificant decrease in efficiency.

Performance and mechanism of enhanced phenolic compounds treatment via mycelial pellets

AbstractBACKGROUNDBiological enhancement in organic wastewater treatment is currently considered an effective and economical method. As a biomass carrier, mycelial pellets are attracting increasing attention, with substantial progress recently being made. To investigate their bioaugmentation effect as a biomass carrier, mycelial pellets with immobilized phenol‐degrading bacteria were applied in a sequencing batch reactor. The phenolic compound removal efficiency of the mycelial pellet‐enhanced system was then studied and compared to the control aerobic activated sludge‐enhanced system. Finally, the settling velocity, internal structure, and surface properties were studied to explore the main bioaugmentation mechanisms of the mycelial pellets.RESULTSThe stable degradation effects of phenolic compounds and total organic carbon (TOC) were observed in both systems. In the mycelial pellet system, the biological removal efficiency was approximately 0.5 mg phenolic compounds L−1 d−1MLSS−1 and 0.4 mg TOC L−1 d−1MLSS−1, which was higher than the aerobic activated sludge system. Bioaugmentation by the pellets was mainly attributed to the structure of the connected macropores, the electrostatic attraction of positive charges, the adsorption of functional groups on the hypha surface, and flocculation due to the extracellular polymeric substances secreted on the pellet.CONCLUSIONThe excellent phenolic compound removal efficiency and bioaugmentation effect of the mycelial pellets suggest their potential to enhance organic wastewater treatment as a biomass carrier. © 2023 Society of Chemical Industry.

Emamectin-sodium alginate nano-formulation based on charge attraction with highly improved systemic translocation and photolysis resistance

Nano pesticides offer an effective means of improving the bioavailability of pesticide due to their excellent solubility and wettability, superior foliar adhesion, and permeability to target insects. By using high-speed homogenization and ultrasonic dispersion technology, an emamectin-sodium alginate nano-formulation (EB@SA) with a particle size ranging from 30 to 50 nm was successfully fabricated using electrostatic self-assembly. The microscopic morphology and structure of EB@SA were further analyzed through transmission electron microscopy, dynamic light scattering, infrared spectroscopy, and 1H NMR. The photolysis resistance behavior of EB@SA demonstrated an improved anti-photolysis ability more than double that of conventional formulations while also exhibiting good sustained-release properties. Not only does EB@SA maintain the inherent insecticidal toxicity of emamectin benzoate (EB), but it also significantly prolongs its insecticidal duration. At a concentration of 20 mg/L, the lethality rate against Armyworms remains above 70 % over a period of 16 days compared to <50 % for general emamectin emulsifiable concentrate. Furthermore, EB@SA greatly enhances the systemic translocation of EB in corn plants by exhibiting favorable bidirectional systemic translocation characteristics. This research presents an efficient and environmentally friendly pesticide nano-formulation that can be effectively utilized for field pest control.

Nonlinear dependence (on ionic strength, pH) of surface charge density and zeta potential in microchannel electrokinetic flow

In this work, a numerical method is proposed to predict the electrokinetic phenomena and combined with an experimental study of the surface charge density (ρs) and zeta potential (ζ) behavior is investigated for borosilicate immersed in KCl and NaCl electrolytes, and for imogolite immersed in KCl, CaCl2, and MgCl2 electrolytes. Simulations and experiments of the electrokinetic flows with electrolyte solutions were performed to accurately determine the electric double layer (EDL), ζ, and ρs at various electrolyte concentrations and pH. The zeta potential was experimentally determined and numerically predicted by solving the coupled governing equations of mass, species, momentum, and electrical field iteratively. Our numerical prediction shows that ζ for borosilicate develops strong nonlinear behavior with the ion concentration following a power-law. Likewise, the ρs obeys a nonlinear behavior, decreasing as the concentration increases. Moreover, for imogolite, both ζ and the ρs behave nonlinearly with the pH. The EDL for borosilicate and imogolite becomes thinner as the electrolyte concentration and pH increase; this behavior is caused by increased ρs, resulting in the higher attraction of the free charges. The reported nonlinear behavior describes more accurately the interaction of the nanoparticle surface charge with the electrolytes and its effect on the electrolyte transport properties.