Electrostatic Attractive Forces Research Articles

Anisole-Water and Anisole-Ammonia Complexes in Ground and Excited (S1) States: A Multiconfigurational Symmetry-Adapted Perturbation Theory (SAPT) Study.

Binary complexes of anisole have long been considered paradigm systems for studying microsolvation in both the ground and electronically excited states. We report a symmetry-adapted perturbation theory (SAPT) analysis of intermolecular interactions in anisole-water and anisole-ammonia complexes within the framework of the multireference SAPT(CAS) method. Upon the S1 ← S0 electronic transition, the hydrogen bond in the anisole-water dimer is weakened, which SAPT(CAS) shows to be determined by changes in the electrostatic energy. As a result, the water complex becomes less stable in the relaxed S1 state despite decreased Pauli repulsion. Stronger binding of the anisole-ammonia complex following electronic excitation is more nuanced and results from counteracting shifts in the repulsive (exchange) and attractive (electrostatic, induction and dispersion) forces. In particular, we show that the formation of additional binding N-H···π contacts in the relaxed S1 geometry is possible due to reduced Pauli repulsion in the excited state. The SAPT(CAS) interaction energies have been validated against the coupled cluster (CC) results and experimentally determined shifts of the S1 ← S0 anisole band. While for the hydrogen-bonded anisole-water dimer SAPT(CAS) and CC shifts are in excellent agreement, for ammonia SAPT(CAS) is only qualitatively correct.

Algae-based self-driven microrobot for efficient removal of nanoplastics from water environment

Nanoplastics (NPs) have the characteristics of various species, wide distribution, low concentration and difficult degradation. In recent years, the researches of NPs have mainly focused on its toxicity, origin and migration, and the quantitative detection and removal technology of NPs is an urgent technical problem to be solved. Here, an active biohybrid microrobots (DPA-algae robots, diphenolic acids-alage robots) was designed and developed for dynamic removal of NPs in water environment. Firstly, diphenolic acids were functionalized on algae to realize the specific adsorption of nanoplastics through hydrophobic force, electrostatic attraction and van der Waals force between diphenolic acids and nanoplastic particles. Secondly, to realize the rapid identification of NPs, the functionalized algae were assembled into microrobots through rapid click chemistry reaction, thus the self-propulsion ability of algae can be utilized to accelerate the identification and enrichment of target objects. The removal rate of nanoplastics by microalgae robots has increased to 83.1 % at the concentration of 0.125 mg/mL within 2 h compared with the unmodified algae, which is a very significant improvement. In addition, the removal rate was 84.1 % to 87.7 % in different media, so the dynamic removal of NPs is expected to be applied into the filtration process of waterworks by preparing a large number of algae-based microrobots. This multi-functional microrobot is cost-effective and biocompatible, providing a new solution to the global “plastic crisis”.

Evaluation of optimized conditions for the adsorption of malachite green by SnO2-modified sugarcane bagasse biochar nanocomposites.

This work deals with the synthesis of SnO2-modified sugarcane bagasse biochar (SnO2-SBB) nanocomposites using an impregnation method. XRD, FTIR, SEM, and EDX analyses were used to characterize the produced nanocomposites. Several factors influencing the removal of malachite green from wastewater via the adsorption process were explored to maximize the effectiveness of this process. These factors included the different doses of nanocomposites, pH, temperature, contact time, etc. Studies on batch adsorption were conducted to examine the impact of operational parameters, such as contact time (5 to 30 minutes), adsorbent dosage (5 to 40 mg), pH (2 to 10), and temperature (303, 323, and 353 K), on the percentage of MG dye removal. The adsorption kinetics of MG dye over SnO2-SBB nanocomposites were evaluated with the aid of the Langmuir adsorption isotherm, which provided a good fit (R 2 = 0.99) for pseudo-second-order kinetics. The thermodynamic parameters revealed spontaneous and exothermic adsorption of MG dye over SnO2-SBB nanocomposites. A maximum adsorption capacity (q max) of 52.64 ± 0.03 for 0.3 SnO2-SBB and 73.86 ± 0.05 for 0.5 SnO2-SBB nanocomposites was observed. The newly synthesized SnO2-SBB nanocomposites showed negative zeta potential, which facilitated the adsorption of hydrated cationic dye molecules due to the electrostatic force of attraction.

Interaction of charged magnetic nanoparticles with surfaces

The behavior of magnetic nanoparticles covering the surface with positive charges (MN), suspended in a continuous medium, was simulated by Brownian dynamics. Then, we studied the behavior of the MN in an aqueous-like suspension and their adsorption on a negatively charged surface, mimicking a mica surface. After several microseconds, particles are deposited onto the charged surface. Experimental results of ordered magnetic nanoparticles in surfaces are compared with the present simulation results of MN in two dimensions. We also demonstrate the effect of charged MN on the hexagonal structure when electrical repulsions dominate against magnetic dipole-dipole and van der Waals attractions. On one hand, the adsorption of MN on the surface depends on the electrostatic attraction force with the surface, while the surface organization of MN results from balancing electrostatic repulsion forces and magnetic attraction forces among particles. In magnetic nanoparticles simulated with a non-charged surface or weakly charged surface, dipole-dipole interactions dominate the particle-particle interactions, and the interactions between particles and a mica-like surface are conducted by van der Waals forces.

Advanced green capture of microplastics from different water matrices by surface-modified magnetic nanoparticles

The extensive production and application of plastic in recent decades has resulted in the presence of microplastics (MPs) in different water bodies. Considered as contaminants of emerging concern (CECs), MPs are accessible to a wide range of organisms and can act as vectors for the transport of other persistent organic pollutants. The existing technologies to remove microplastics from wastewaters and prevent their intrusion in nature, still present several limitations, resulting in an urgent need to develop novel, fast, cost-effective and greener alternatives. In this work, the magnetophoretic capture of MPs by their assembly with magnetic nanoparticles through either electrostatic interactions or molecular forces is investigated. For the experimental assessment, magnetic nanoparticles were synthesized by hydrothermal coprecipitation and solvothermal decomposition methods, while polyethylene (PE) microspheres were selected as model microplastic pollutants. As a noteworthy novelty, thermal decomposition and coprecipitation particles were functionalized with amino groups and sodium alginate (SA), respectively, resulting in a modification of their surface properties and enhanced electrostatic or molecular interactions with MPs. After preliminary experiments, a concentration of 1.3 g L-1 and a contact time of 20 min between magnetic nanoparticles and MPs, were selected as operating conditions to assess the influence of the functional groups on the capture performance. The influence of other variables in the process was also evaluated, including the magnetic nanoparticles synthesis method, the pH of the medium, varied in the range 4–8, and the water constituents that may be present in water bodies. Results demonstrated that the presence of different types of polar groups on the surface of the magnetic nanoparticles make them interact towards MPs through electrostatic attraction or molecular forces, considerably enhancing the capture performance of bare magnetic nanoparticles. This work represents a step forward in the development of new and reliable techniques for the environmentally friendly capture of microplastics from polluted waters.

The decisive role of filtration reducers’ surface charge in affecting drilling fluid filtration performance

To elucidate the effects of filtration reducers’ surface charge on drilling fluid filtration performance, three kinds of SiO2@polymer nanoparticles with different surface charges are prepared. When these nanoparticles are added into bentonite-based drilling fluids as filtration reducers, the negatively charged nanoparticles show the best filtration reduction performance while the positively charged nanoparticles show the most inferior filtration reduction performance. Moreover, more negative charges induce better filtration reduction performance. Conversely, more positive charges induce more inferior filtration reduction performance. The filtration performance of drilling fluids is decided by the compactness of the filter cake. And the interactions among the particles in the drilling fluids play an important role in affecting the compactness of filter cake. The electrostatic attraction forces between the positively charged nanoparticles and negatively charged bentonite particles promoted the aggregation before the formation of incompact filter cake, and the electrostatic repulsion forces between the negatively charged nanoparticles and negatively charged bentonite particles slowed down the aggregation of particles to form more compact filter cakes. These findings demonstrate the decisive role of surface charge of filtration reducers, which could provide guidance for searching suitable filtration controlling additives for drilling fluids in the future.

Regulation research on weak co-adsorption and nonsteady-state capture for C6H6/CO2 over carbon materials

With the intention of capturing both benzene (C6H6) and carbon dioxide (CO2) from indoor air, it is assuring of getting both C6H6 and CO2 simultaneously adsorbed over activated carbon materials. Thus, in this study, how adsorption of C6H6 and CO2 performs over single-wall carbon materials is minutely investigated via density function theory (DFT). Specifically speaking, direct electronic interaction between C6H6 and CO2, co-adsorption features and nonsteady-state capture processes of C6H6/CO2 over single-wall carbon nanotube (CNT) as well as regulation of CNTs towards more stable adsorption are main contents in this study. According to results, C6H6 and CO2 are weakly mutually attracted because of limited electrostatic attraction forces and hydrogen-bond effects, which are also the major reason for consequent weak co-adsorption state over pure CNT. In the meantime, owing to repulsive forces of π-orbital electrons from pure CNT to C6H6, both of C6H6 and CO2 could be only captured by pure CNT in nonsteady state. However, with phosphorus (P) and aluminum (Al) embedded as dopants, surficial electron distribution is altered to a large degree and local electron-enriched centers of modified CNTs are formed to enhance connection with C6H6/CO2, especially stronger electrostatic positron–electron attraction and faster capture speeds from free-state to adsorption-state at relatively high temperatures. Overall, this study provides plentiful information of utilizing single-wall carbon materials for fast indoor air purification in a passive way.

Synthesis of porous carbon/zeolite composites by low-temperature acid-alkaline leaching from coal gasification fine slag for adsorption of dye wastewater

The conversion and utilization of coal gasification slag is considered one of the key issues in the development of the modern coal chemical industry. In this work, porous carbon/Na-P1 zeolite composites were successfully prepared by a simple and easy-to-operate acid-alkali leaching method on the basis of the composition of coal gasification fine slag. The synthesized CZ-10 possessed a honeycomb-like porous carbon structure and a typical flower-cluster zeolite structure, with the specific surface area and pore volume reaching 195.68 m2/g and 0.257 m3/g, respectively. CZ-10 showed excellent adsorption performance, with an equilibrium adsorption capacity of 175.93 mg/g on methylene blue (MB) at 300 K. CZ-10 can effectively adsorb MB in a wide pH range, and the increase in pH was favorable for adsorption. According to the results of adsorption kinetics and isothermal adsorption experiments, the adsorption process was in good agreement with PSO model and Sips model. According to the characterization results and adsorption experiments, it was speculated that the adsorption of CZ-10 on MB was mainly chemisorption, and may be affected by various factors such as ion-exchange, electrostatic attraction, hydrogen bonding, π-π bonding and van der Waals forces.

Theoretical study on the capture of toxic gases by ionic liquids encapsulated in assembled belt[14[pyridine

In the current study, self-assembled belt[14]pyridine (BP) encapsulated IL (tetramethylammonium chloride (TMACl)) is theoretically explored to capture greenhouse gases (GHGs) at B3LYP-D3/6-311G(d,p) level of theory. The encapsulation of TMACl in assembled belt[14]pyridine is thermodynamically feasible as revealed through high interaction energy value of −50.7 kcal/mol. Moreover, the results of capturing of gas molecules (SO2, CO2, CO and CH4) show that attractive forces involved in capturing of gases are strong van der Waals forces i.e., London dispersion forces and electrostatic interactions. The synergic effect of self-assembled belts and ionic liquid results in significantly high interaction energy values ranging from −7.88 to −25.92 kcal/mol for capturing of gas molecules. Furthermore, the interaction between BP-TMACl and gas molecules is studied in detail through natural bond orbital (NBO) analysis. NBO results show the charge transfer between the fragments (BP-TMACl and gases) which is further validated through EDD analysis. The charge shifts towards all of the captured gas molecules but the most prominent change in NBO charges is shown by captured SO2. The successful charge transfer indicates better interaction in the designed systems. Additionally, the type and strength of interactions involved in the process of encapsulation is studied through quantum theory of atoms in molecules (QTAIM) and noncovalent interactions (NCI) analysis. NCI analysis clearly shows that gases are captured by BP-TMACl complex through strong van der Waals forces. However, in capturing of SO2, strong electrostatic attractive forces are also involved. The nature of attractive forces is confirmed through QTAIM analysis. Furthermore, the relation between recovery time and desorption energy of captured gas molecules has been studied. The strongest absorption for SO2 results in prolonged recovery time for it (as compared to the other gas molecules). AIMD analysis is performed to find the dynamical stability of assembled-belts before and after loading ionic liquids along with gases to be captured. These results reveal that assembled-belts are suitable for encapsulation of ionic liquids along with capturing of gases. Overall, the best results are shown for SO2 capture. The study intends to deliver valuable information on the important progress in the environmental-remediation field and we hope our work is going to inspire more investigators to provide novel research on such challenging tasks.

Effects of surface property on loading octaaza bis-α-diimine Ni complex, charge separation, and H2 production activity of MnS@ZnS photocatalysts

The MnS@ZnS photocatalyst was prepared using a microwave-assisted solvothermal method. Then, the octaaza bis-α-diimine Ni complex was loaded to prepare a composite photocatalyst. The adsorption of metal complex on photocatalyst depends on the anchoring groups of the Ni complex and the colloidal surface charge of the photocatalyst. The effects of the zeta potential of MnS and MnS@ZnS photocatalysts on the loading of Ni complex, separation of photogenerated carriers, and activity of Ni complex-modified composite photocatalysts were studied. The loading of NiC complex in photocatalysts was analyzed by Raman spectra, TEM line scan, mapping images, and total reflection x-ray fluorescence spectrometer. MnS@ZnS photocatalyst exhibits negative zeta potential that provides a strong electrostatic attraction force between photocatalysts and the Ni complex (Columb attraction), leading to increased Ni complex loading. MnS@ZnS/Ni complex exhibits better photocatalytic activity than MnS/Ni complex. Loading the Ni complex facilitates the photosensitization of photocatalysts, resulting in improved light absorbance. Besides, the electron-hole separation was further improved because the Ni complex acted as a redox mediator, enabling the transfer of electrons from MnS@ZnS to the Ni complex. The H2 production activity of MnS@ZnS/Ni complex photocatalyst reaches 3997 μmol h−1g−1, which is 1.72 times the pristine MnS.

Fabrication of date palm kernel biochar-sulfur (DPKB-S) for super adsorption of methylene blue dye from water

A novel form of biochar was created by dehydration of Date palm kernel with 85% sulfuric acid. It was examined how the newly produced biochar (DPKB-S) affected the aqueous solution's capacity to extract Methylene Blue (MB) dye. The prepared DPKB-S was categorized by BET, BJH, FT-IR, SEM, EDX, DSC, and TGA analyses. The ideal pH for the MB dye adsorption by DPKB-S is 8. With 0.75 g L−1 of DPKB-S and an initial concentration of 50 ppm MB dye, Date Palm Kernel Biochar-Sulfur (DPKB-S) had the highest removal percentage of 100%. The Langmuir and Freundlich isotherm models were used to investigate the collected data. Freundlich model is the model that best covers MB dye adsorption in DPKB-S at low concentrations (0.75–1.25 g L−1) and the Langmuir model at high concentrations (1.5–1.75 g L−1). The Langmuir model maximum adsorption capacity (Qm) of the DPKB-S was 1512.30 mg g−1. Furthermore, a variety of error function models were applied to investigate the isotherm models derived data, including Marquardt’s percent standard deviation (MPSD), the sum of absolute errors (EABS), the sum of the errors squared (ERRSQ), root mean square errors (RMS), Chi-square error (X2), the average relative error (ARE), average percent errors (APE), and hybrid error function (HYBRID). Kinetic data were calculated by intraparticle diffusion (IPD), pseudo-second-order (PSO), pseudo-first-order (PFO), and film diffusion (FD) models. A PSO rate model with a strong correlation (R2 = 1.00) largely regulated the adsorption rate. The removal mechanism of MB dye by DPKB-S is based on the principle that these positively charged dyes are attracted by electrostatic attraction forces due to the growth in the number of negatively charged regions at basic pH value. According to the results, DPKB-S shows promise as an affordable and competent adsorbent for the adsorption of MB dye. It can be used frequently without experiencing a discernible decrease in adsorption efficiency.

3D Multimodal, omnidirectional router of aqueous microdroplets based on the synergy of photovoltaic and triboelectric effects

In this paper, we present a 3D multimodal router for aqueous microdroplets, addressing the ongoing challenge of 3D transportation of microdroplets in free space. Our strategy combines the photovoltaic effect of a LiNbO3:Fe substrate with the triboelectric effect of a superhydrophobic coating. We demonstrate that by positively charging the aqueous microdroplets through the contact-electrification process while they roll or elongate on the superhydrophobic surface, we can achieve their controlled and electrostatically ballistic ejection for free-space transportation. Leveraging the superfast and repetitive laser-scanning capabilities of a laser marking system, we develop various 2D/3D routing modes that utilize repulsive or attractive electrostatic forces to deflect or trap the microdroplets in parallel or cascading configurations. We propose a 3D routing mode suitable for photosensitive microdroplets, employing asynchronous illumination with an appropriate ON/OFF duty ratio. We also enable the 3D omnidirectional routing of initially motionless and traveling microdroplets using toroidal and linear laser-scanning, respectively, thus facilitating the transportation of sequential microdroplets in overpass configurations. Our proposed technique opens up new possibilities for free-space microfluidics, enabling the complex delivery of biochemical substance.

Chitosan-modified iron fillings materials for remediation of arsenic-contaminated soil

Arsenic (As) contamination of soils adversely affects human health and ecosystems and is an environmental issue of serious concern worldwide. Efficient and economical remediation methods are urgently needed. In this research, a chitosan-modified scrap iron filings (CFF) composite was prepared by using industrial scrap iron filings and chitosan to stabilize As-contaminated soil. The optimal modification conditions were explored, and CFF was applied to As-contaminated soil to investigate its remediation effect and stabilization mechanism. The results showed that the optimal preparation conditions of CFF were chitosan concentration of 3.75 % (w/w), chitosan to scrap iron filings ratio of 1:1, optimal modification temperature of 40 °C, iron filings particle size of 35–80 mesh, and 10 % glutaraldehyde crosslinking for 6 h, and the stabilization efficiency of As was 73.98 %. The adsorption behavior of CFF was consistent with the pseudo-second-order kinetic model and the Langmuir isotherm model, and the best adsorption effect was achieved at pH = 5–6. The possible mechanisms of As stabilization by CFF were surface complexation, hydrogen bonding synergy, precipitation, electrostatic attraction, and van der Waals forces.

Mechanism and performances of methyl orange and Congo red adsorption by MnO2–PVP composite

Abstract Azo dyes are commonly used in textile industries; however, when these dyes cross the permissible limit set by the World Health Organization, they produce many health issues related to the brain, liver, kidneys, respiration, and sexual system. Herein, polyvinyl pyrrolidone (PVP)-supported manganese oxide (MnO2) was studied for azo dye removal from an aqueous medium. The adsorption mechanism study demonstrated that the dye adsorption by MnO2–PVP composite was not only due to the electrostatic force of attraction but also involved the ion exchange amid the hydroxide group and dye molecules. The surface area of the composite (120 m2 g−1) was larger than that of metal oxide (102 m2 g−1). The point of zero charge and surface area were improved from 5.2 and 102 to 5.6 and 120 m2 g−1, respectively. The dye removal capacity of MnO2–PVP composite was significantly higher than that of plain MnO2. The film diffusion control adsorption kinetic mechanism and the kinetic data were well fitted to the pseudo-second-order equation. Experiments were conducted as a function of initial dye concentration (5–200 mg L−1), pH (3–10), temperature (298–328 K), and adsorbent dosage (0.05–0.4 g) in batch adsorption systems. The thermodynamic investigations confirm that the dye adsorption process was endothermic in nature.

The influence of nitrogen-containing functional groups and pore structure on the adsorption of per- and polyfluoroalkyl substances in ultrapure and real water

Activated carbon adsorption has been identified as an effective technique for per- and polyfluoroalkyl substances (PFAS) removal. However, the role of nitrogen-containing functional groups and pore size on PFAS elimination is uncertain. Therefore, this study prepared a series of AC with different nitrogen groups and pore structures by thermal treatment with urea under different temperatures (denoted as AC400, AC600 and AC800). Their PFAS adsorption performance in ultrapure and real water were investigated to identify the contribution of different nitrogen groups and pore structures. The adsorption experiment indicated that the modified AC800 with high proportion of pyridine nitrogen and medium pore volume achieved the best performance in ultrapure water due to the electrostatic interaction. However, in the real water contained dissolved organic matter (DOM), rather than AC800, AC600 with large mesopore volume exhibited the maximum adsorption capacity and kinetic due to its better inhabitation of pore blockage by DOM. It could be inferred that the electrostatic attraction force was more important in PFAS adsorption in ultrapure water, but in real water the mesopore volume was more critical due to the pore blockage by DOM. This study can provide guidance and implications for selection and development of future PFAS adsorption carbon-based material.

Appraisal of the adsorption potential of novel modified gellan gum nanocomposite for the confiscation of methylene blue and malachite green

In the present investigation a novel, environmentally affable and economical, modified gellan gum nanocomposite (MAA-g-GG/Ppy/MMT) was fabricated via free-radical polymerization for the liquid-phase mitigation of Methylene blue (MB) and Malachite green (MG) dyes. The innovation of this work is substantiated by the intentional combination of diverse materials, the strategic incorporation of polypyrrole for enhanced adsorption, and the thoughtful addition of MMT as a nanofiller to address mechanical strength and improve adsorption capacity. The physico-chemical facets of MAA-g-GG/Ppy/MMT and its interaction with the dye molecules were elucidated using FT-IR, SEM-EDX, BET, TEM, and XRD techniques. The optimum conditions for the sorption of MB and MG were deemed to be dosage (1.2 g/L for both dyes), contact time (50 min for both dyes), initial MG/MB concentration (MB = 40 mg/L & MG = 30 mg/L), and pH (MB = 10 & MG = 7). The Freundlich isotherm was identified as the most suitable model, as evidenced by the highest R2 value (∼0.999), indicating multilayer adsorption. The pseudo second-order model appraised the kinetic data. Thermodynamic findings revealed the adsorption process to be spontaneous, viable and exothermic which was ascertained by negative ∆H⸰ values (−22.8 kJ/mol for MB and −18.3 kJ/mol for MG). The substantial Langmuir adsorption capacity (Qm: MG =185.185; MB = 344.827) can be ascribed to the reason for strong interactions between MAA-g-GG/Ppy/MMT and dyes. The high reliability of MAA-g-GG/Ppy/MMT was determined by the regeneration studies that worked up to four cycles for both dyes. The real water (distilled water, tap water, and river water) samples spiked with MG/MB demonstrated a substantial uptake of dyes (>85 %) and the marginal influence of ionic strength on the adsorptive potential of MAA-g-GG/Ppy/MMT validated its efficacy for the decontamination of real effluents. The forces of attraction between the dyes and MAA-g-GG/Ppy/MMT included van der Waals, electrostatic forces of attraction, and π-π interaction. This green, economical, and viable MAA-g-GG/Ppy/MMT will prove to be an efficient adsorbent for the decontamination process of sequestration of dyes to achieve a sustainable environment.

Evaluating the potential of vancomycin-modified magnetic beads as a tool for sample preparation in diagnostic assays.

Vancomycin-functionalized micro- or nanoparticles are frequently used for isolation and enrichment of bacteria from various samples. Theoretically, only Gram-positive organisms should adhere to the functionalized surfaces as vancomycin is an antibiotic targeting a peptidoglycan precursor in the cell wall, which in Gram-negative bacteria is shielded by the outer cell membrane. In the literature, however, it is often reported that Gram-negative bacteria also bind efficiently to the vancomycin-modified particles. The goal of our study was to identify the underlying cause for these different findings. For each species several strains, including patient isolates, were investigated, and effects such as day-to-day reproducibility, particle type, and the antimicrobial effect of vancomycin-coupled beads were explored. Overall, we found that there is a strong preference for binding Gram-positive organisms, but the specific yield is heavily influenced by the strain and experimental conditions. For Staphylococcus aureus average yields of approximately 100% were obtained. Respectively, yields of 44% for Staphylococcus cohnii, 22% for Staphylococcus warneri, 17% for Enterococcus faecalis and 5% for vancomycin-sensitive Enterococcus faecium were found. Yields for Gram-negative species (Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii) and vancomycin-resistant Enterococcus faecium were below 3%. Our results indicate that the interaction between vancomycin and the D-alanine-D-alanine terminus of the peptidoglycan precursor in the bacterial cell wall is the dominant force responsible for the adherence of the bacteria to the particle surface. It needs to be considered though, that other factors, such as the specific molecules presented on the bacterial surface, as well as the pH, and the ion concentrations in the surrounding medium will also play a role, as these can lead to attractive or repulsive electrostatic forces. Last but not least, when using colony forming unit-based quantification for determining the yields, the influence of cell cluster formation and different sensitivities towards the antimicrobial effect of the vancomycin beads between species and strains needs to be considered.

Single-Electrode Electrostatic Repulsion Phenomenon for Remote Actuation and Manipulation.

One of the fundamental principles of electrostatics is that an uncharged object will be attracted to a charged object through electrostatic induction as the two approaches one another. We refer to the charged object as a single electrode and examine the scenario where a positive voltage is applied. Because of electrostatic induction phenomenon, single-electrode electrostatics only generates electrostatic attraction forces. Here, we discover that single-electrode electrostatics can generate electrostatic repulsion forces and define this new phenomenon as single-electrode electrostatic repulsion phenomenon. We investigate the fundamental electrostatic phenomena, giving a curve of electrostatic force versus voltage and then defining 3 regions. Remote actuation and manipulation are essential technologies that are of enormous concern, with tweezers playing an important role. Various tweezers designed on the basis of external fields of optics, acoustics, and magnetism can be used for remote actuation and manipulation, but some inherent drawbacks still exist. Tweezers would benefit greatly from our discovery in electrostatics. On the basis of this discovery, we propose the concept of electrostatic tweezers, which can achieve noncontact and remote actuation and manipulation. Experimental characterizations and successful applications in metamaterials, robots, and manipulating objects demonstrated that electrostatic tweezers can produce large deformation rates (>6,000%), fast actuation (>100 Hz), and remote manipulating distance (~15 cm) and have the advantages of simple device structure, easy control, lightweight, no dielectric breakdown, and low cost. Our work may deepen people's understanding of single-electrode electrostatics and opens new opportunities for remote actuation and manipulation.

Preparing Multi-Functional Protein Textiles by the Flavonoid-Rich Ginkgo Biloba L. Leaf Extracts

ABSTRACT Flavonoids in ginkgo biloba L. leaf (abbreviated as GBL) extracts exhibited superior biological activity, but their light color limited their development in the field of textiles. Therefore, this work innovatively used GBL extracts as textile functional finishing agent, through exhaustion dyeing process endowed protein fabrics the multifunction. Flavonoids of GBL in protein fabrics showed outstanding rubbing and washing fastness, becuase of their formed strong affinity by electrostatic attraction, hydrogen bond and van der Waals force. Moreover, the flavonoid content on protein fibers was enhanced by the GBL extract concentration increase, treating time stretch, temperature improve. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy result that flavonoids in GBL extracts adsorbent the fibers. In addition, the treated protein fabrics possessed good antioxidant, antibacterial and heavy metal protective performance. Finally,GBL dyed silk fabrics exhibited stronger functionalities than GBL dyed wool fabrics. This work provides the methods that reuse GBL waste and functionalization of protein fabric.

Efficient adsorption of fluorescent whitening agent 351 from high salinity environmental water by polymer supported hydroxyl functional ionic liquid

Fluorescent whitening agent 351 (FWA351) is an emerging highly persistent pollutant with potentially harmful effects on human health and aquatic ecosystem. However, developing highly effective adsorbents for the pre-treatment of environmental water samples containing FWA351 remains a problem. In this study, a novel polymer supported hydroxyl-functionalized ionic liquid (PS-[HMMim][Cl]) was prepared via a simple one-step method and used for the removal of FWA351 from water. It was found that the PS-[HMMim][Cl] exhibited an ultrahigh adsorption capacity of 1203.6 mg/g for FWA351 and maintained high removal efficiency in a wide pH range (2.0–9.0). Notably, even the concentration of FWA351 was as low as 0.005 mg/L (5 ppb), FWA351 could be effectively removed by the adsorbent, achieving an enrichment factor as high as 447.8. Various inorganic salts (such as KCl, NaCl and MgCl2) at the concentration up to 1.0 mol/L had no obvious effect on the removal efficiency. The PS-[HMMim][Cl] also displayed outstanding adsorption performance towards fluorescent whitening agents (FWAs) with similar structure to FWA351 and could be regenerated and reused for at least 8 cycles. Finally, the adsorbent was applied for the pre-treatment and then detection of FWA351 in six kinds of environmental water samples. Mechanism studies suggest that the synergistic driving forces of electrostatic attraction, hydrogen bonding, π-π interaction and ion exchange are responsible for the efficient adsorption of FWA351. This work provides a new strategy for efficient adsorption and analysis of FWA351.