Electrostatic Attractive Forces Research Articles

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.

Recycling enzymatic hydrolysis lignin residues saved cellulase in enzymatic hydrolysis of lignocellulose: An insight from cellulase adsorption mechanism

Enzymatic hydrolysis lignin residues (EHLRs) of lignocellulose usually adsorbs cellulase, which can be recycled and used to replace parts of cellulase in the hydrolysis process. To understand this phenomenon during enzymatic hydrolysis (EH) of sugarcane bagasse (SCB) treated with sulfite (SPORL) and dilute acid (DA), the adsorption characteristics between lignin and cellulase in EHLRs were investigated, focusing on interaction force at molecular level and enzymatic activity. The results revealed that SPORL-EHLR adsorbed more β-glucosidases (β-GLs) through the stronger electrostatic attraction and hydrogen bond force, causing higher cellulase adsorption amount compared to DA-EHLR. Further exploration demonstrated that the cellobiose’s catalytic and binding sites on β-GLs were separated from the binding site of SPORL-EHLR on β-GLs, resulting in minimal inhibition of β-GLs activity when bound to SPORL-EHLR. Furthermore, adding SPORL-EHLR in SCB hydrolysis saved 40% cellulase. This study deepens the understanding of the adsorption behavior between lignin and cellulase.

Adsorption of cobalt (II) ions from aqueous solution using cow bone and its derivatives: Kinetics, equilibrium and thermodynamic comparative studies

Mono-component adsorption of Co2+ ions from simulated industrial water was investigated by using cow bone (CB), cow bone char (CBC), and activated cow bone carbon (ACBC) adsorbents synthesized from raw cow bone as the precursor. The resulting prepared adsorbent materials were then characterized using analytical methods such as: zeta potential measurements, BET surface area, FTIR, SEM, EDS, and XRD analysis. For all synthesized adsorbents, the main compositions were mesopores with the presence of CC, PO32−, CO32 and O-H bonds signifying hydroxyapatite nature of the adsorbents. The isoelectric point (pHIEP) of ACBC was obtained to be 3.59 (lowest among the prepared adsorbents) thereby signifying that ACBC's electrostatic force of attraction was relatively higher between the Co2+ and its surface. The study showed that the pseudo second-order kinetic model had the best correlation for all the adsorption kinetic experimental data for each prepared adsorbent, inferring that the rate-controlling step during the Co2+ ions adsorption onto the prepared adsorbents is chemisorption. The Sips isotherm model excellently predicted the adsorption data for the adsorption of Co2+ ions on the CB adsorbents while the Langmuir isotherm best fitted the equilibrium data of the CBC, and ACBC prepared adsorbents with excellent correlation coefficients, while maximum adsorption capacities, qmax, were obtained to be 52.50, 58.80, and 64.50 mg g−1 for CB, CBC, and ACBC respectively. The study of the thermodynamic properties of the adsorption of Co2+ showed the process was endothermic, non-spontaneous and endogenic for the ACBC adsorbent, while being exothermic for the CB, and CBC adsorbents in addition to having physisorption properties.

Graphene oxide@Fe3O4-decorated iota-carrageenan composite for ultra-fast and highly efficient adsorption of lead (II) from water

The aggravated problem of lead pollution, especially in aquatic environments, necessitates the development of eminent adsorbents that could radically solve this environmental problem. Hence, a new composite was constructed based on iota carrageenan (i.Carr), graphene oxide (GO) and magnetite (Fe3O4) for removing noxious Pb2+ ions. The GO@Fe3O4-i.Carr composite was characterized by VSM, SEM, XPS, XRD, FTIR and Zeta potential. The removal of Pb2+ ions attained a quick equilibrium of almost 30 min with a removal efficiency reaching 93.68 %. The removal of Pb2+ was boosted significantly, in the order of GO@Fe3O4-i.Carr(1:1) > GO@Fe3O4-i.Carr(1:3) > GO@Fe3O4-i.Carr(3:1). Moreover, acquired experimental data fitted the pseudo 2nd order kinetic model and Freundlich isotherm model with a maximal monolayer adsorption capacity reached 440.05 mg/g. Notably, after five adsorption runs, the composite maintained its removal efficiency exceeding 74 %. The assumed adsorption mechanisms of Pb2+ onto GO@Fe3O4-i.Carr were complexation, precipitation, Lewis acid-base, and electrostatic attraction forces. Overall, the GO@Fe3O4-i.Carr composite elucidated the auspicious adsorbent criteria, comprising fast adsorption with high performance, ease-separation and tolerable recyclability, advising its feasible use to decontaminate water bodies from hazardous heavy metals.

Quantum Chemical Simulations of CO2 and N2 Capture in Reline, a Prototypical Deep Eutectic Solvent.

Deep eutectic solvents such as reline are an emerging class of low-cost, environmentally friendly solvents with tunable properties that are potentially applicable for the capture and separation of CO2. Experimental measurements showed that a reline-based membrane contactor can capture and separate CO2 via physisorption through a dissolution process with 96.7% purity from a mixed gas containing CO2 and N2 (50:50% molar ratio). We examine the nature of the interaction of CO2 and N2 with reline employing quantum chemical methods. We focus on explaining the mechanism by which CO2 and N2 bind to reline and the reason for the high selectivity for absorption of CO2 compared to N2. We analyze the dynamics, energetics, and binding motifs for CO2 and N2 in reline employing density functional theory, density functional tight binding, and ab initio molecular dynamics. We also investigate the effect of reline on the vibrational spectra of CO2 and reline. Our simulations indicate that the selective capture of CO2 from the mixture of CO2 and N2 is due to the interplay between attractive electrostatic and charge polarization forces with opposing entropic effects, which shift the energetic balance and make the N2 absorption unfavorable in reline.

Synthesis and exploration of physical properties of nanobiochar synthesized from rice straw for its applications in arsenic remediation from contaminated water environments

Arsenic (As) is a widespread carcinogenic element that emerges due to geogenic and anthropogenic processes and poses detrimental effects on public health. Biochar is a carbonaceous, renewable, and sustainable material synthesized under low or absent oxygen. Thus, the present study explores the application of biochar obtained via pyrolysis at 500 °C for 2 hrs, followed by ball milling for 3 hrs at 500 rpm to obtain nanobiochar materials for As removal from contaminated environments. Characterization of biochar has been performed for physico-chemical analysis. Different functional groups, including hydroxyl, carboxyl, and alkene, are observable using Fourier Transform Infrared Spectroscopy, contributing to As removal from water. Scanning Electron Microscope analysis shows the porous nature of nanobiochar, which also contributes to remediation. Transmission electron microscope analysis shows an average particle size of nearly 28.12 nm. The As(V) removal efficiency was obtained with an adsorption capacity of 55.1 µg/g at pH 8 to mimic natural water conditions for 6 hrs of biochar-arsenic interactions. The possible adsorption mechanisms of As species on biochar surfaces are electrostatic attractive forces, surface chemical bonding, ion exchange, and precipitation. Future research must concentrate on applications of low-cost, renewable, and carbon material, i.e., biochar for decontaminating natural groundwater samples containing various emerging contaminants for safe and clean drinking water.

Modeling, optimization and comparative study on abatement of fluoride from synthetic solution using activated laterite soil and fly ash

The supply of potable water by proper treatment of fluoride laden ground water is a challenging task. Batch experiments were executed with activated laterite soil and fly ash individually for removal of fluoride. The process parameters such as particle size (100–620 μm), dose of adsorbent (10–60 g/L), initial concentration of fluoride (2–12 mg/L), agitation speed (20–120 rpm), contact time (0.5–10 h) and pH (4.5–9.5) were investigated and it was observed that activated laterite soil had better fluoride removal efficiency than fly ash. At pH 4.5, contact time 10 h, particle size 100 μm, adsorbent dose 60 g/L, initial concentration of fluoride 12 mg/L, and agitation speed 120 rpm, maximum removal efficiencies of fluoride using activated laterite soil and fly ash were found as 85.91 ± 0.62% and 77.1 ± 0.39%, respectively. Kinetic study was performed and Pseudo 2nd order kinetic model was found to fit the kinetic data best. The Freundlich isotherm model fit the equilibrium data fairly well. The values of adsorption equilibrium constant as used in Freundlich isotherm model vis-à-vis adsorption capacity (KF) for activated laterite soil and fly ash were obtained as 0.1331 and 0.0772 ((mgg−1)(Lmg−1)1/n). A thermodynamic analysis was conducted to examine the process behaviour. In order to determine whether the adsorbent may be used for further cases, regeneration of the adsorbents was also done. Generally, two types of adsorption mechanisms happen like electrostatic attraction and ion exchange. The electrostatic force of attraction favours the adsorption of negatively charged fluoride ions on positively charged adsorbent surfaces. In ion exchange, fluoride ions are exchanged by hydroxyl and hydronium ion. Based on experimental data, Multi-Gene Genetic Programming (MGGP) model could accurately predict the removal efficiency of fluoride under various operating situations. Finally, using Genetic Algorithm (GA) optimization the maximum output values for both adsorbents were estimated as 99.14% and 99.02%.

Enabling efficient water desalination and mitigating membrane fouling by the novel two-dimensional fullerene with unlocking its electrostatic forces

Graphene-based two-dimensional (2D) materials are currently a prominent focus in membrane research, yet they face challenges related to precise perforation and regulation of interface activity. Recently, the successful synthesis of 2D fullerene (C60) (Meirzadeh et al., Nature 2023, 613, 71) has expanded the repertoire of available 2D materials. However, its potential for membrane separation remains unexplored until now. In this study, we propose, for the first time, the utilization of 2D C60 for water desalination, leveraging its natural pores to circumvent the perforation challenge and allowing for precise tuning of interface activity. By establishing quantitative relationships between water flux and various operating conditions, this theoretical work can be extrapolated to guide practical desalination processes. Through non-equilibrium molecular dynamics simulations, it demonstrates that pristine 2D C60 exhibits unparalleled water permeance and achieves 100% salt rejection, regardless of operating pressure or the types of salt ions. To enhance desalination performance, we further propose a rational design strategy using endohedral 2D C60 with a positively charged surface, which improves water permeance up to 29.3 L⋅cm−2⋅day−1⋅MPa−1 and simultaneously reduces crystallization and colloidal fouling on the membrane surface by unlocking electrostatic attraction and repulsion forces, respectively. The mechanism behind this exceptional performance is attributed to the existence of well-endowed nanopores that form a connected hydrogen bond network, enabling swift vertical flow of water through the channels. Our findings showcase the exciting prospects of the novel 2D C60 material and provide a compelling new approach to membrane-based desalination, with the potential to revolutionize membrane materials.

Inhibitory effect of cyclodextrin on Maillard reaction and its mechanism

Maillard reaction in pharmaceutical preparations refers to a complex chemical reaction existing between reducing excipients and amino-containing drugs in preparations, which can cause a series of quality problems in preparations. Maillard reaction belongs to chemical incompatibility in preparations, and measures should be taken to reduce or avoid it. In this study, the effect of cyclodextrins (commonly used pharmaceutical excipients) on the Maillard reaction and its mechanism in the lysine hydrochloride-lactose solid preparation model were explored for the first time. Our research results show that the embedding of lysine in cyclodextrin can inhibit the Maillard reaction of lysine to some extent, and the embedding of lysine in cyclodextrin with different structures has differences in the inhibitory effects on Maillard reaction.Among the five cyclodextrins we studied, α-CD and HP-β-CD embedded lysine can reduce Maillard reaction to a greater extent. We suspect that this may be related to the stability of the embedded substance, which needs further study and verification. And our research shows that the inclusion complex between lysine and cyclodextrin may be the result of hydrogen bond, electrostatic attraction, hydrophobic interaction and van der Waals force. Cyclodextrin is expected to solve the problem of Maillard reaction in pharmaceutical industry to some extent.

Ag@rGO coral reef morphology exhibits excellent optical properties and photocatalytic activity against methyl orange under sunlight

The modified hummers method was used to synthesize GO, and the coral reef shape morphology of Ag@rGO was synthesized through the chemical reduction method. As-synthesized GO, rGO, Ag NPs, and Ag@rGO were characterized using various characterization techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectra, UV–Vis diffuse reflectance spectroscopy (UV-DRS), X-ray photoelectron spectrometer (XPS), N2 adsorption-desorption isotherms (BET), liquid chromatography with mass spectrometry LCMS, Moreover, thermal stability was studied using a thermogravimetric analyzer (TGA). The growth size, shape, and extent were studied using transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The obtained material was partially in de-agglomerated and agglomerated form, and aggregation was due to electrostatic forces of attraction. Besides this, the synthesized GO (70 %), rGO (85 %), Ag NPs (92 %), and Ag@rGO (99 %) were utilized to investigate photocatalytic activity for the degradation of Methyl orange dye (MO) under sunlight. Ag@rGO shows effective catalytic activity as it degrades the azo dye effectively. The degradation was found to be maximum using Ag@rGO, showing 99 % (120 min).

Diffusion Coefficient of Phosphate Ion in Citric Acid-Agarose Gel Used in Diffusive Gradient in Thin Films (DGT) Passive Sampler

In this research, the diffusion coefficient of phosphate ions in agarose-citric acid diffusive gel has been studied. The agarose-citric acid diffusion layer was prepared by mixing 1.5% agarose solution with the addition of citric acid solutions at various concentration. The diffusive gel was casted between two glass plates which were separated using a spacer of 0.1 cm thickness and clamped together in the three sides. Gel was formed for 15 minutes in an oven at 40oC. The diffusion coefficient then was calculated using Fick's First law formula. Gel that produced with addition of 0.45% citric acid absorbed more water during immersion in water for 3 hours for facilitating phosphate diffusion. Swelling degree of the agarose citric acid diffusive gels was not affected by the storing solution condition either in water or in NaNO3 0.1 M. Coefficient diffusion of phosphate in the agarose-citric acid diffusive gel was 1.009×10-7 cm2s-1, less than the diffusion in the pure agarose gel 1.367×10-7 cm2s-1. The diffusion is affected by the ionic strength of solution. Phosphate diffusion coefficient is higher in the phosphate solution with addition of 2 mgL-1 nitrate. Increasing the ionic strength causes lower phosphate diffusion coefficient because the electrostatic attractive and repulsive force

A detailed insight into the adsorption efficiency of Cr(VI) by a novel polypyrrole modified kendu (Diospyros melanoxylon Roxb) seed biochar

The occurrence of heavy metals in drinking water is a foremost health concern in today’s world. The use of naturally occurring biomass for the removal of toxic pollutants from water is a proficient and inexpensive treatment method. Based on a comprehensive study of the pyrolysis features, pore configuration, chemical functionality, and carbon framework, we report a cost-effective polypyrrole-modified kendu (Diospyros melanoxylon Roxb) seed-derived biochar (PPY-KSC) via oxidative polymerization. The potentiality of hexavalent chromium decontamination from an aqueous solution was assessed by applying PPY-KSC as a bio-adsorbent. Synthetic steps were designed and the reusability of biomass was investigated by taking the minimum toxicity of the environment into account. The 1:1 V/W (volume/weight) ratio of pyrrole and KSC was optimized for the production of PPY-KSC considering the effectiveness of Cr(VI) removal. All the synthesized biochar were characterized following several techniques such as TEM, SEM, FTIR, XRD, Raman, Zeta potential, BET, and TGA analysis. SEM, TEM, and BET analysis proposes that PPY-KSC exhibited a spherical polypyrrole chain with an uneven microporous structure having an elevated surface area (81.55 m2/g) than KSC. PPY-KSC showed efficient Cr(VI) adsorption (98.8%) for 30 mg adsorbent dose in 100 mL of 10 ppm of Cr(VI) solution in 70 min at room temperature. Cr(VI) adsorption was following the pseudo-second-order kinetic model besides obeying the Langmuir isotherm model with R2 = 0.99 and a Langmuir adsorption capacity of 81.96 mg/g. Furthermore, a simultaneous physio-chemical process along with microporous capture governs adsorption. The Intraparticle diffusion model demonstrates the chemical interaction between polypyrrole and chromium through the electrostatic force of attraction. The thermodynamic parameters signify the remediation of Cr(VI) was irreversible, spontaneous, feasible and endothermic. The present approach allows reusability and studies showed that PPY-KSC owes the sorption property being 81.5% efficient up to five consecutive cycles.

Removal of antibiotic resistance genes from wastewater using diethylaminoethyl cellulose as a promising adsorbent

The implications associated with the emergence of antibiotic resistance genes (ARGs) are dangerous, and there is an urgent need for their effective removal from the environment. The current study is a comprehensive evaluation of the potential of diethylaminoethyl cellulose (DEAE-C) to target the adsorptive removal of ARGs using a template DNA under different working conditions like varying adsorbate concentrations, time, working pH, coexisting anions and real waste water matrix. The obtained results exhibited excellent adsorption efficiency of DEAE-C with high Langmuir maximum adsorption capacity of 65.40 μg/mg at pH 7 ± 0.5. The adsorption process was majorly governed by the electrostatic force of attraction. Desorption study was performed for the adsorbent reusability. Maximum desorption was attained at pH 8 ± 0.5 using 2 ml 0.5 M NaCl. The adsorbent exhibited great recyclability up to 10 regeneration cycles without any significant loss in its performance. Finally the adsorbent tested in real wastewater matrix for real ARGs and mobile genetic elements selected on the basis of size and abundance namely 16srRNA gene, bla CTXM, and int 1 exhibited high adsorption ability. Almost 4–4.45 log gene copies reduction of studied ARGs was achieved in real wastewater matrix. Overall the DEAE-C was observed to be an excellent adsorbent material to target the efficient removal of antibiotic resistance genes from wastewater. Moreover the present study will help and give a perspective to the scientific community to develop an efficient, practical and appropriate technology to target the removal of ARGs from wastewater.

Tangential electrostatic field at metal surfaces

Abstract In electrodynamics, it has been long believed that when the electrostatic equilibrium is reached the electrostatic field outside a metal is always perpendicular to the metal surface. However, the tangential electrostatic field (TEF) may be discovered at the metal surface through the mechanical-electric coupling in the work. The TEF can lead to new knowledge and more accurate modification on electrostatics of metals including the electrostatic equilibrium conditions, uniqueness theorem, method of image charges, electrostatic shielding, Thompson’s theorem, and Green’s reciprocation theorem. The TEF and the mechanical-electric coupling can also indicate that an intrinsically intensive electrostatic field may exist at the nanoparticle surface. Thereby a unified model could be constructed for the surface-enhanced Raman scattering (SERS) which has been a long-standing problem in physics and chemistry in recent several decades. Furthermore, when the micro-electro-mechanical systems (MEMS) work, the deformation of the metal plate can induce an additional electrostatic field and a newly attractive electrostatic force between the metal plates. They may be important for the design and fabrication of high-performance MEMS devices. Overall, the revealed TEF may update the physical knowledge of the electrostatics of metals in electrodynamics and may acquire widespread applications in the areas of SERS, MEMS, and so on.

Anti-Inflammatory Activity of Phytoconstituents of Ginseng Plant- Insilico Approach

Ginseng is a plant’s root of the Panax family that is characterized by the presence of ginsenosides. It is used as a traditional medicine for many years in East Asian regions generally as an adaptogenic medicine to make the body resistant to homeostasis and other adverse environmental factors. Inflammation and lipid signaling are intermixed modulators of homeostasis and immunity. Cyclooxygenase is a key enzyme in lipid signalling. The present study focused on the anti-inflammatory analysis of phytoconstituents of the ginseng plant against COX1 and COX2 genes. In this study we approached the study of the interaction of phytoconstituents of ginseng plant with COX-1 and COX-2 using an insilico approach. It is done in 2 main stages: docking between COX1 and COX2 with phytoconstituents of ginseng plant and the ADMET analysis. . The drug-likeness of phytoconstituents were predicted and the ADMET properties. Molecular docking studies were done using the Autodock server and MyPresto program to explore the binding pattern with COX-1 and COX-2. The result showed that phytoconstituents gallic acid and myricetin have high anti-inflammatory action due to the electrostatic force of attraction of COX1 and COX2. Quercetin, and apigenin due to high binding affinity due to the attraction of COX2, epicatechin, and chlorogenic acid on COX1. The phytoconstituents gallic acid, myricetin, apigenin, chlorogenic acid, epicatechin and quercetin can potentially be used as anti-inflammatory agents.

Boosting the piezoelectric coefficients of flexible dynamic strain sensors made of chemically-deposited ZnO nanowires using compensatory Sb doping

The piezoelectric devices made of ZnO nanowires have received a great interest in the past decade as potential nanogenerators and sensors. However, their characteristics are still limited significantly by the screening of the piezoelectric potential generated under mechanical solicitations, originating from the high density of free electrons in ZnO nanowires. In order to tackle that issue, we develop the compensatory Sb doping of ZnO nanowires grown by chemical bath deposition, both in the low- and high-pH regions using Sb glycolate and ammonia as chemical additives. The adsorption process of Sb(III) species on the positively charged surfaces of ZnO nanowires proceeds through attractive electrostatic forces, resulting in the significant incorporation of Sb dopants with an atomic ratio in the range of 0.11–0.45%. The optical properties of Sb-doped ZnO nanowires exhibit additional phonon modes related to Sb dopants in the range of 500–750 cm-1 in the Raman spectra, and some specific characteristics in the nature and intensity of radiative recombination in the cathodoluminescence spectra. Importantly, the integration of Sb-doped ZnO nanowires encapsulated in PMMA and grown on PDMS into flexible piezoelectric dynamic strain sensors is shown to drastically boost the piezoelectric charge and voltage coefficients by a factor of 2.65 and 1.91, following the significant incorporation of Sb dopants. A subsequent thermal annealing under oxygen atmosphere is revealed to further increase the piezoelectric charge and voltage coefficients by an additional factor of 1.38 and 1.49, following the activation of Sb doping and engineering of hydrogen-related defects. Two figures-of-merit are eventually derived from the piezoelectric charge and voltage coefficients and their values for flexible piezoelectric composites made of annealed Sb-doped ZnO nanowires are compared to more conventional piezoelectric materials, showing their high potential for medical devices. The present findings highlight the strategy consisting in simultaneously introducing compensatory acceptors and engineering hydrogen-related defects to reduce the screening effect, representing an additional powerful way to enhance the characteristics of the piezoelectric devices integrating ZnO nanowires.

Scavenging of copper(II) ions, phosphate(V) ions, and diuron from aqueous media by goethite modified with chitosan or poly(acrylic acid)

Goethite was modified by chitosan (CS) or poly(acrylic acid) (PAA) to improve its adsorptive abilities toward components of agrochemicals, i.e., copper ions (Cu), phosphate ions (P), and diuron. The pristine goethite effectively bound Cu (7.68 mg/g, 63.71%) and P (6.31 mg/g, 50.46%) only in their mixed systems. In the one adsorbate solutions, the adsorption levels accounted for 3.82 mg/g (30.57%) for Cu, 3.22 mg/g (25.74%) for P, and 0.15 mg/g (12.15%) for diuron. Goethite modification with CS or PAA did not yield spectacular results in adsorption. The maximum increase in adsorbed amount was noted for Cu ions (8.28%) after PAA modification as well as for P (6.02%) and diuron (24.04%) after CS modification. Both goethite modifications contributed to clear reduction in desorption of pollutants (even by 20.26% for Cu after PAA coating), which was mainly dictated by electrostatic attractive forces and hydrogen bonds formation occurring between macromolecules and impurities. The only exception in this phenomenon was Cu desorption from CS-modified solid—the polymer made it higher (to 95.00%). The Cu adsorption on PAA-modified goethite enhanced solid aggregation and thus facilitated metal cation separation from aqueous media. Consequently, the goethite modification with PAA was considered more promising for environmental remediation.

Insights into the influence mechanism of different interlayer cations on the hydration activity of montmorillonite surface: A DFT calculation

Montmorillonite is one of the main components of mudstones. Physical changes in the microstructure of montmorillonite after water absorption are the root cause of softening and disintegration of mudstone and the deterioration of bearing properties. In this study, the adsorption behavior and hydration mechanism of water molecules on the surface of four cationic forms of montmorillonites (LiMt, NaMt, KMt, and CaMt) were investigated by density functional theory (DFT). The results indicated that water molecules were adsorbed mainly through electrostatic attractive force with interlayer cations. The electrostatic attraction decreased in the following order: Ca-Mt > Li-Mt > Na-Mt > K-Mt; and CaMt demonstrated the strongest adsorption capacity. When adsorption occurred, there was a large charge transfer between the atom of a water molecule (Ow) and interlayer cations, and the hybridization of Ow 2p orbitals with Li 1 s, Na 3 s, K 4 s, and Ca 4 s orbitals formed bonds with certain ionic characteristic. This work directly explained the interaction mechanism of water molecules with montmorillonite at the atomic and electronic levels, which provided a new perspective to understand the adsorption process of water molecules on clay mineral surfaces.

Effect of goethite (α-FeOOH) nanoparticles on the surface properties and flotation behavior of chalcopyrite

Chalcopyrite flotation is selectively depressed by oxidation treatment. The presence of ferric oxyhydroxide on the surface of chalcopyrite after oxidation treatment is a key factor in depressing chalcopyrite flotation. However, there is no concrete evidence that ferric oxyhydroxide has a depressing effect. In addition, the effectiveness of this depressing effect could be enhanced by directly applying ferric oxyhydroxide nanoparticles. This study investigated the effect of goethite (α-FeOOH) nanoparticles on the surface properties and flotation behavior of chalcopyrite. α-FeOOH nanoparticles were produced through chemical precipitation followed by hydrothermal treatment. The crystalline structure of irregular rice grain-shaped α-FeOOH nanoparticles was confirmed by the X-ray diffraction pattern and scanning electron microscope image. Micro-flotation experiments showed that chalcopyrite recovery decreased significantly from 93 % to 13 % when 30 mg/L α-FeOOH nanoparticles was used. This flotation result demonstrated the potential of α-FeOOH nanoparticles as a nanodepressant for the flotation of chalcopyrite. These nanoparticles physically adsorbed on the chalcopyrite surface and rendered its surface hydrophilic, thereby reducing the chalcopyrite flotation recovery. The attractive electrostatic force between the positively charged α-FeOOH nanoparticles and the negatively charged chalcopyrite surface is likely responsible for the adsorption of α-FeOOH nanoparticles on chalcopyrite.