Electrostatic Attractive Forces Research Articles

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.

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.