Spontaneous Adsorption Research Articles

Bacterial valorization of agricultural-waste into a nano-sized cellulosic matrix for mitigating emerging pharmaceutical pollutants: An eco-benign approach

For Bacterial Nanocellulose (BNC) production, standard methods are well-established, but there is a pressing need to explore cost-effective alternatives for BNC commercialization. This study investigates the feasibility of using syrup prepared from maize stalk as a valuable nutrient and sustainable carbon source for BNC production. Our study achieved a remarkable BNC production yield of 19.457 g L−1 by utilizing Komagataeibacter saccharivorans NUWB1 in combination with components from the Hestrin-Schramm (HS) medium. Physicochemical properties revealed that the obtained BNC exhibited a crystallinity index of 60.5 %, tensile strength of 43.5 MPa along with enhanced thermostability reaching up to 360 °C. N2 adsorption-desorption isotherm of the BNC displayed characteristics of type IV, indicating the presence of a mesoporous structure. The produced BNC underwent thorough investigation, focusing on its efficacy in addressing environmental concerns, particularly in removing emerging pharmaceutical pollutants like Metformin and Paracetamol. Remarkably, the BNC exhibited strong adsorption capabilities, aligning with the Langmuir isotherm and pseudo-second-order model. Thermodynamic analysis confirmed a spontaneous and endothermic adsorption process. Furthermore, the BNC showed potential for regeneration, enabling up to five recycling cycles. Cytotoxicity and oxidative stress assays validated the biocompatibility of BNC. Lastly, the BNC films displayed an impressive 88.73 % biodegradation within 21 days.

Onion Peel Extract/Copper Oxide Nanoparticles as Corrosion Inhibitors for Carbon Steel in Hydrochloric Acid: Extraction, Characterization, Electrochemical Study, and Theoretical Explorations

The effectiveness of onion peel extract (OPE) as a corrosion inhibitor for carbon steel in a 1 M hydrochloric acid solution was investigated using weight loss (WL) techniques, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and surface morphological examination. Additionally, this process was characterized by Fourier transform infrared (FT-IR) spectroscopy, energy dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), atomic force microscopy (AFM), and transmission electron microscopy (TEM). According to weight loss measurements, the protective efficiency of OPE increases with rising OPE concentration and decreases with increasing temperature of the corrosive solution. Polarization curves indicate that OPE acts as a mixed-type inhibitor in hydrochloric acid. The adsorption mechanism, supported by EIS results, shows that charge-transfer resistance increases and double-layer capacitance decreases with higher inhibitor concentration. The adherence of OPE to carbon steel follows the Langmuir isotherm, indicating a physical adsorption process, and the spontaneous adsorption of the inhibitor molecules is evidenced by the negative values of Gibb’s free energy of adsorption. The synergistic effect of copper oxide nanoparticles (CuO–NPs) in combination with OPE on the corrosion inhibition of carbon steel was also evaluated. The results demonstrated that the inhibition efficiency of OPE is enhanced in the presence of CuO–NPs due to synergistic interactions between OPE extract molecules and CuO–NPs. The electron-donating capacity of the chemical components in OPE was confirmed through theoretical studies employing quantum chemistry methods.

Effective removal of heavy metals from aqueous solutions using activated biomass: Analytical interpretation via molecular dynamic simulation, mathematical and statistical approaches

Activated carbons basis on low-cost natural materials, Diplotaxis harra (DH) and Glebionis coronaria L. (GCL) were prepared by chemical activation. The optimization of the manufacture conditions is performed by the full factorial design with four variables. Indeed, four activated carbons are prepared, DHACH3PO4, GCLACH3PO4, DHAC-KOH et GCLAC-KOH. The approach used has been evaluated regarding Cd(II) and Co(II) sorption capacities. The optimal conditions for activated carbons preparation are investigated. Therefore, the equilibrium study is assumed using Langmuir and Freundlich isotherm models. Under the optimum conditions, the highest adsorption of Cd(II) is acquired at 118.75 mg/g onto GCLACH3PO4. However, the greater efficiency of Co(II) sorption is obtained onto DHAC- H3PO4 and it was 82.55 mg/g. The current optimization overviews the Cd(II) and Co(II) removal involving various activated carbons. In the theoretical approach, the adsorption affinity of the heavy metal is computed using molecular dynamics (MD) simulation and compared with the adsorption affinity obtained from the experiment. The adsorption energy values were fitted to an empirical interaction energy model to predict the binding energy of arbitrary pollutants. This study used MD simulation to investigate the adsorption mechanism of Cd(II) on the AC (002) surface. The adsorption and interaction energies indicated a feasible, exothermic, and spontaneous adsorption process. MD simulations demonstrate that the adsorption process of Cd(II) on activated carbon is chemical in nature. This result is confirmed by the radial distribution function (RDF) analysis. This research adds new theoretical and experimental findings about heavy metal adsorption using activated carbon.

Synthesis and characterization of a novel TiO2@chitosan/alginate nanocomposite sponge for highly efficient removal of As(V) ions from aqueous solutions: Adsorption isotherm, kinetics, experiment and adsorption mechanism optimization using Box-Behnken design

This research uses a novel TiO2@CSC.Alg composite sponge was created by encasing TiO2 nanoparticles in the natural polymers alginate and chitosan, resulting in a nanocomposite that is both ecologically friendly and biocompatible. Using the generated nanocomposite as a new environmentally friendly adsorbent, As(V) heavy metal ions were effectively removed from aqueous media. The following techniques were used to analyse the physicochemical properties of the obtained materials: pHZPC, FTIR, XRD, BET, SEM, and XPS. Utilizing nitrogen adsorption/desorption isotherms, the TiO2@CSC.Alg composite sponge's textural properties were identified. This revealed a BET surface area of 168.42 m2/g and a total pore volume of 1.18 cc/g, indicating its porous nature and potential for high adsorption capacity. Examine the effects of temperature, pH, dose, and beginning concentration on adsorption. The adsorption characteristics were determined based on equilibrium and adsorption kinetics measurements. The adsorption process was both pseudo-second-order (PSOE) and Langmuir isothermally fit. Chemisorption was the adsorption method since the adsorption energy was 25.45 kJ·mol−1. An endothermic and spontaneous adsorption process was indicated by more metal being absorbed as the temperature increased. The optimal conditions for adsorption were optimized via Box-Behnken design software to be pH of 5 in the solution, a dosage of 0.02 g of the TiO2@CSC.Alg composite sponge per 25 mL, and an arsenate (As(V)) solution the adsorption capacity was 202.27 mg/g are ideal for efficient adsorption. These parameters are critical in achieving the maximum adsorption capacity of the composite sponge for arsenate, which could be beneficial for water purification applications. Utilizing Design-Expert software's response surface methodology (RSM) and Box-Behnken design (BBD), the adsorption process was optimized with the fewest planned tests. After six successive cycles of adsorption and desorption, the adsorbent stability was confirmed by the adsorbent reusability test without any noticeable decrease in removal efficacy. Additionally, it displayed good efficiency, the same XRD and XPS data before and after reuse, and no change in chemical composition.

Efficient removal of sparfloxacin antibiotic from water using sulfonated graphene oxide: Kinetics, thermodynamics, and environmental implications

Pharmaceutical contamination poses a significant threat to global health. Due to their high solubility in water, antibiotics are difficult to remove. This study produced and used sulfonated graphene oxide (SGO) to adsorb sparfloxacin from aquatic environments. UV–Visible, Fourier transform infrared (FTIR), X-ray diffraction (XRD), XPS, SEM, TEM, EDX, particle size, Thermogravimetric analysis (TGA), and acid-base titration were used to characterize synthesized SGO particles. The BET technique determined SGO's surface area (32.25 m2/g). The calculated pHPZC of SGO was 2.5. Sparfloxacin adsorption onto SGO was analyzed using adsorption duration, medium pH, adsorbent dosages, antibiotic concentration, cations, and solution temperature. The pseudo-second-order kinetic model better described experimental kinetic data than the pseudo-first-order and Elovich models. Equilibrium isotherm data supported the Langmuir model, revealing a peak absorption capacity of 1428.57 μmol/g at 25 °C. The kinetic and isotherm models' applicability was assessed using error analysis. A thermodynamic analysis revealed an endothermic, spontaneous adsorption process with a change in entropy (ΔS) of 114.15 J/mol K and enthalpy (ΔH) of 8.44 kJ/mol. A regeneration analysis showed that SGO adsorption efficiency topped 86.4 % after five cycles.

The inhibitive action of lemon verbena plant extract as an economical and eco-friendly corrosion inhibitor for mild steel in acidic solutions

The inhibitive effect of lemon verbena (lemon v.) extract as a green corrosion inhibitor (CI) for mild steel (st37) in 0.5 M H2SO4 and 1 M HCl media at room temperature is investigated by employing electrochemical current noise (ECN), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and scanning electron microscopy (SEM). The achievements demonstrated that the inhibition efficiency increases with increasing the extract concentration up to 2000 ppm in 0.5 M H2SO4 and up to 2500 ppm in 1 M HCl solutions and decreases with an increase in temperature. The ECN results show when Lemon V. extract is included to both acidic media, the values of commotion charges (Q) diminished. The least value of the Q is 15 and 60 mCoul in H2SO4 and HCl media, respectively. The EIS measurements depicted that by addition of the inhibitors up to a certain concentration, the charge transfer resistance increases up to 186 Ω cm−2 in H2SO4 and 350 Ω cm−2 in HCl, besides the double layer capacitance (Cdl) decreases. Potentiodynamic polarization assessments indicated that Lemon V. acts as mixed type inhibitor. Certain thermodynamic parameters were determined based on the temperature impact on inhibition and corrosion processes. The extract adsorption on the surface of the alloy follow the Langmuir adsorption pattern. A mixed mode of adsorption was observed, wherein the extract in H2SO4 and HCl predominantly underwent chemisorption. Thermodynamic parameters indicated spontaneous adsorption and exothermic process with increasing entropy in H2SO4 and decreasing entropy in HCl. SEM investigation also validated the adsorption performance of the inhibitor.

Grape seeds waste activated carbon as an adsorber of paracetamol drug residue: Experimental and theoretical approaches

Activated carbon (AC) derived from grape seeds wastes and chemically activated with phosphoric acid was employed to remove paracetamol (PCT); from an aqueous solution; as a pharmaceutical compound model. The AC was characterized using several techniques, and a series of batch adsorption experiments were conducted. Additionally, a theoretical study investigated the interactions of PCT with various functional groups present on the AC surface. The results demonstrated that the developed AC possessed a well-developed pore structure and a high specific surface area (SBET = 543 m2/g). The AC also exhibited an acidic surface and a low pHpzc (2.5). Adsorption experiments revealed that the pseudo-second-order (PSO) and Freundlich models provided the best fits for experimental kinetic and equilibrium data, respectively. The maximum adsorption capacity of AC for PCT was found to be 17.3 mg/g. Thermodynamic analysis suggested endothermic, favorable, and spontaneous adsorption; with low enthalpy values (ΔH° = 8.099 kJ/mol), supporting physisorption. The DLPNO-CCDT(T)/6-311G(d,p) calculation method yielded the most reliable adsorption energy (Eads) and Gibbs free energy (ΔGads) values between PCT and functional groups on the carbon surface, indicating strong interactions between the acid phosphate group of AC and the acetamide fragment of PCT (ΔGads = −7.60 kcal/mol), and strong interactions between the ketone groups and lactone cycles with the hydroxyl (ΔGads = −3.40 kcal/mol), and acetamide (ΔGads = −1.91 kcal/mol) groups of PCT, respectively. The obtained results indicated, first, that the use of activated carbon from waste is an effective alternative adsorbent for the treatment of wastewater containing pharmaceutical compounds. Second, the application of theoretical computational methods in quantum chemistry provides a thorough understanding of the mechanism of the absorption of PCT at the carbon surface.

Innovative modification of cyclodextrin metal-organic frameworks for enhanced adsorption in wastewater treatment

The synthesis of aminopyrimidine-modified cyclodextrin metal-organic frameworks (AP-β-CD-MOF) at room temperature with pentanal as a cross-linking agent is the main objective of this work. This process introduces additional adsorption sites and highly delocalized conjugated systems, consequently enhancing the adsorption performance of material. The maximum adsorption capacity for CR (pH = 6) and TC (pH = 6) are found to be 317.5 mg/g and 166.4 mg/g. Furthermore, the adsorption isotherms for CR and TC conform to Freundlich and Langmuir models, revealing an endothermic and spontaneous adsorption process through thermodynamic analysis. Additionally, after four reuse cycles, the adsorption rates remained at 86 % for CR and 71 % for TC. Analysis using zeta potential, FTIR, and XPS confirms that the adsorption mechanism of CR primarily involves electrostatic interactions between sulfonyl groups and amino pyridine, whereas Tetracycline's driving force predominantly relies on π-π EDA interactions. This study lays a solid foundation for further exploration of low energy modified CD MOFs and has important research significance.

Removal of Lead Using Novel Composite Synthesized from Rice Husk and Used Tea Leaves Extract

Untreated industrial effluents, particularly from tanneries and heavy industries, are the main source of heavy metal pollution, which poses serious environmental risks. Lead is one of the most toxic heavy metals, adversely affects human functioning and accumulates in the environment. This study presents ACUTLaqE (Activated Carbon-Used Tea Leaves Aqueous Extract) as an effective adsorbent for Pb2+ ion removal from their aqueous solution. The composite was synthesized by blending activated carbon from rice husks with a tea extract solution and characterized using SEM, XRD, and FTIR spectroscopy. Batch tests demonstrated that ACUTLaqE is highly efficient, removing about 99% of Pb2+ ions at an adsorbent dose of 2 g/L within 30 minutes. The adsorption data conformed well to the Langmuir isotherm model, suggesting a homogeneous monolayer formation on the composite surface. The qm was 38.61 mg/g, with an RL value close to 0, indicating highly favourable adsorption. Thermodynamic parameters showed negative Gibbs free energy (ΔG⁰) values, reflecting a spontaneous adsorption process. The enthalpy (ΔH⁰) and entropy (ΔS⁰) changes were 66.86 KJmol-1 and 257.12 JK-1mol-1, respectively. The adsorption mechanism involved electrostatic interactions and surface complexation with the composite's hydroxyl and carboxyl groups. These findings suggest that ACUTLaqE is a promising adsorbent material for Pb2+ and potentially other heavy metals removal from industrial effluents.

Bili leaf extract: Green corrosion inhibitor for zinc in hydrochloric acid-experimental and theoretical study

The primary goal of this study was to examine whether Bili leaf extract (BLE) (Aegle marmelos leaf) could inhibit zinc corrosion in an acidic environment, specifically in 0.05–0.10 M HCl solutions. The corrosion rate was examined using PDP (Potentiodynamic Polarization), EIS (Electrochemical Impedance Spectroscopy), and weight loss techniques. The research attains notable inhibition efficiencies of 99.0 %, 83.4 %, and 78.95 % in weight loss, PDP, and EIS respectively, at a concentration of 2.0 g/L BLE and a temperature of 303 K. The influence of temperature (ranging from 303 to 333 K) on the corrosion behaviour was examined upon the addition of BLE. As the concentration of BLE increased, the corrosion rate(CR) of Zn decreased, and a similar reduction was observed with decreasing temperature. Adsorption of BLE onto the metal surface followed by Langmuir and Freundlich adsorption isotherm models. The activation parameters of BLE and its negative Gibbs free energy indicate spontaneous adsorption rates. Tafel polarization measurements showed that BLE acts as a mixed-type corrosion inhibitor, meaning it influences anodic and cathodic reactions. FT-IR spectroscopy is employed to determine the functional groups of BLE. Atomic Force Microscopy(AFM)/Energy Dispersive X-ray (EDX)/Scanning Electron Microscopy (SEM) images of the zinc surface verified a significant reduction in surface inhomogeneities when BLE was present. The quantum parameters obtained through DFT(Density Functional Theory)/MD (Molecular Dynamics) demonstrated excellent agreement with the experimental findings.

Inclusive study of peanut shells derived activated carbon as an adsorbent for removal of lead and methylene blue from water

Green and efficient agro-waste-based activated carbon has been prepared utilizing peanut shells for adsorptive elimination of an industrial dye, methylene blue, and lead from polluted water. The carbonaceous biomass obtained from peanut shells was chemically activated using either NaOH, ZnCl2, or steam and characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and N2 adsorption and desorption studies. The adsorption process was optimal for methylene blue at alkaline pH, while pH 4.5 was optimal for Pb (II) adsorption. The adsorption takes place through pseudo-second-order kinetic, and the rate-governing step of the adsorption procedure are intraparticle diffusion and film diffusion. Furthermore, the thermodynamics of the adsorption process has been studied, and the obtained Gibbs free energy (ΔG°) values are negative (− 35.90 to − 43.59 kJ mol−1) indicating the spontaneous adsorption of the investigated pollutants on the prepared activated carbon. As per the correlation coefficient, the obtained results were best fit by the Langmuir isotherm with maximum adsorption capacity of 303.03 mg g−1 for methylene blue and 130.89 mg g−1 for Pb (II). The activated carbon successfully removed methylene blue and Pb (II) with %removal exceeding 95%. The mechanisms of interaction of Pb (II) with the activated carbon is a combination of electrostatic interaction and ion exchange, while methylene blue interacts with the activated carbon via π–π interaction, hydrogen bonds, and electrostatic interaction. Thus, the prepared activated carbon has been employed to decontaminate wastewater and groundwater samples. The developed agro-waste-based activated carbon is a promising, cost-efficient, green, and accessible tool for water remediation.

Response surface methodology and experimental evaluation of the inhibitory properties of corn leaf extract for aluminum corrosion in acid media

PurposeThis study aims to develop eco-friendly corrosion inhibitors for aluminum in acidic media by evaluating the corrosion inhibition properties of corn leaf extract (CLE) using response surface methodology (RSM) and experiments.Design/methodology/approachThe RSM was combined with experiments to evaluate the corrosion inhibition properties of CLE on aluminum in acid media.FindingsThe effectiveness of the inhibition increased with increasing inhibitor concentration and time but decreased with increasing temperature. The corrosion inhibition mechanism revealed the corrosion process is spontaneous exothermic physical adsorption. Thermodynamic parameters revealed an activation energy between 32.1 and 24.7 kJ/mol, energy of adsorption between −14.53 and −65.07 and Gibbs free energy of −10.12 kJ/mol which indicated the CLE exothermically spontaneously physisorbed. A model was generated to estimate the effect of the process parameters (inhibitor concentration, reaction time and temperature) using the RSM. Optimization of the process factors was also carried out using the RSM. The percentage inhibition efficiency obtained experimentally (85.61%) was closely comparable to 84.89% obtained by the theoretical technique (RSM). The SEM observations of the inhibited and uninhibited Al samples demonstrated that CLE is an effective corrosion inhibitor for aluminum in acid media.Originality/valueResults herein provide novel information on the possible application of CLEs as effective eco-friendly corrosion inhibitors.

Eco-Engineered Low-Cost Carbosorbent Derived from Biodegradable Domestic Waste for Efficient Total Chromium Removal from Aqueous Environment: Spectroscopic and Adsorption Study

Chromium contamination in water bodies poses severe risks to both the environment and human health. This research introduces an innovative solution to this challenge by creating a vapor-activated carbosorbent from biodegradable household waste. The efficacy of this adsorbent in removing total chromium through batch methods from aqueous solutions was investigated. Surface analysis using scanning electron microscopy (SEM) exhibited a porous structure, while Fourier-transform infrared spectroscopy (FTIR) identified distinct functional groups on the surface. The point of zero charge (PZC), determined at 6.95, revealed the adsorbent’s surface chemistry. Impressively, the synthesized carbosorbent exhibited significant adsorption capacities of 23.08 mg.g-1 for Cr(III) and 24.84 mg.g-1 for Cr(VI) under optimal conditions. The Langmuir isotherm model illustrated a monolayer adsorption mechanism aligned with the pseudo-second-order kinetic model, confirming chemisorption. Thermodynamic analysis disclosed favorable and spontaneous chromium adsorption. Negative ΔG° values affirmed the spontaneity, while the exothermic nature of the process was signified by the positive ΔH° value, indicating heat release. Increased randomness at the solid-liquid interface, indicated by the positive ΔS° value, underscored the enhanced affinity between the adsorbent and adsorbate. This study exemplifies the potential of the vapor-activated carbosorbent as an efficient and sustainable remedy for chromium-contaminated water bodies.

Amidoxime functionalized magnetic MXene/chitosan composites for efficient uranium extraction

Uranium extraction from unconventional uranium resources is among the major constraints to the development of the nuclear industry at present. In this dissertation, we here propose to effectively graft amidoxime groups on magnetic MXene and chitosan (CS) composites to extract uranium from low-enriched uranium solutions (MCF-AO). The data of adsorption experiments displayed that MCF-AO possessed fast adsorption kinetics (within 120 min), outstanding selectivity and salient adsorption capacity (1305.7 mg/g at pH=4, T=298.15 K) for uranium and could be easily separated with a magnet. Adsorption studies revealed a behavior consistent with the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model, which is suitable for the spontaneous heat-absorption chemical monolayer adsorption process. Its sorption remains at more than 55 % of the original after 5 adsorption-desorption tests, and has great tolerance to interfering ions. Mechanistic research pointed out that the selective adsorption of uranium by MCF-AO was significantly enhanced by the presence of hydroxyl, amino and amidoxime groups. Meanwhile, MCF-AO exhibited superb resistance to two common bacteria (E. coli and B. subtilis) and achieved more than 95 % uranium extraction capacity in simulated seawater, even more 4.12 mg/g of uranium extraction in Salt Lake water. Consequently, MCF-AO has a broad application prospect in the recovery and treatment of complex uranium systems.

Exploring the mechanism of nerve agent (Tabun and Sarin) adsorption on carbon nanocones: Computational insights

Carbon NanoCones (CNCs), distinguished by their conical shape and large surface area, are evaluated for their potential application in nerve gas [tabun (GA) and sarin (GB)] adsorption. Density Functional Theory (DFT) calculations, Molecular Dynamics (MD), and Monte Carlo (MC) simulations are employed to investigate this phenomenon comprehensively. The study findings indicate that tabun (GA) and sarin (GB) undergo spontaneous adsorption, characterized by significant negative energy values. Density Functional Theory (DFT) calculations indicate electron donation tendencies of nerve agents to CNC surfaces. Computational analysis shows higher adsorption efficiency in the inner portion (P1) of CNCs. Molecular Dynamics (MD) and Monte Carlo (MC) simulations confirm planar adsorption configurations parallel to CNC surfaces. The DFT calculations show that GA has a far greater adsorption energy on a Carbon Nanocone compared to GB (−44.96 kcal/mol for GA, whereas GB has an adsorption energy of −35.95 kcal/mol). Furthermore, the analysis reveals significant differences between Sarin and Tabun nerve agents. Sarin exhibits higher global hardness, indicating increased stability, while Tabun shows higher overall softness, suggesting greater reactivity. Despite similar electronegativities, Sarin’s greater ionization energy and electron affinity imply enhanced stability and reactivity. Differences in HOMO and LUMO energies highlight unique reactivity profiles, with Sarin being more susceptible to nucleophilic attacks and Tabun to electrophilic attack. Sarin’s larger energy gap between HOMO and LUMO orbitals signifies its superior stability under electronic disturbances.

Adsorption isotherm, kinetic and thermodynamic studies for adsorption of fluoride on waste marble powder

Economically viable, efficient waste marble powder (WMP) for fluoride removal has been studied. A batch adsorption study has been carried out concerning contact time, initial concentration, adsorbent dosage, pH, and temperature. After using a batch adsorption mode, 97.13 % removal efficiency was observed with an adsorption capacity of 1.166 mg/g at the initial fluoride concentration of 6 mg/L, solution pH of 6, adsorbent dosage of 500 mg, temperature of 35 °C, and contact time of 60 min. According to kinetics studies, the experimental adsorption data fit well in a nonlinear pseudo-second order with the adjusted-R2 value 0.999, and the nonlinear Langmuir isotherm model fitted best with the adjusted-R2 value 0.988. The separation factor (RL) values were within the range of 0.178 - 0.086, suggesting a satisfactory uptake of fluoride ions. Thermodynamic analysis showed that the adsorption process was endothermic, and negative values of Gibbs free energy change (∆Go) indicated spontaneous fluoride adsorption. In contrast, a positive value of entropy change (∆So= 65.26) indicated arbitrary behaviour at the interface between the solid and the solution. Fluoride removal from aqueous solution was also studied using a continuous fixed-bed column. The Yoon-Nelson model, with a higher adjusted-R2 value of 0.9906, described the dynamics of the fluoride adsorption process better than the Adams-Bohart model because it had better predictions for the breakthrough curve. According to the regeneration analysis, 52 % of the adsorption rate with an adsorption capacity of 0.604 mg/g could be achieved even after five cycles of WMP regeneration.

Battling hazardous gas molecules with kekulene surfaces: A computational study

A Density Functional Theory were used to investigate the interactions between kekulene and various noxious gases, including methane(CH4), carbon dioxide (CO2), hydrogen(H2), ammonia(NH3), and sulfur dioxide(SO2). The adsorption energies and bond distances were computed, indicating successful molecular interactions with kekulene, particularly notable in the exothermic nature of the adsorption process. Enthalpy calculations further confirmed the exothermic nature of the reactions, suggesting spontaneous adsorption. The analysis of frontier molecular orbitals revealed distinctive electronic characteristics, with HOMO-LUMO plots indicating a significant energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Chemical descriptors derived from these calculations provided insights into the reactivity and polarizability of the compounds. Furthermore, the molecular electrostatic potential (MEP) surface maps illustrated the electrostatic potential distribution, aiding in predicting the molecule’s reactivity. Overall, the study highlights the potential of kekulene as a selective adsorbent for toxic gas (SO2), offering valuable insights into its chemical and electronic properties for various applications, particularly in environmental and industrial settings.

Exploring Ginkgo biloba extract's green corrosion inhibition effects on Q235 steel in H2SO4 environments

The corrosion inhibition properties of Ginkgo biloba extract on Q235 steel in 0.5 M H2SO4 solution were comprehensively investigated using weight loss measurements, electrochemical techniques, surface characterization, and quantum chemical calculations. The results demonstrate that Ginkgo biloba extract acts as an effective green corrosion inhibitor, with inhibition efficiencies reaching up to 96.54% at a concentration of 0.7 g/L. The inhibition efficiency increased with increasing extract concentration and temperature. FTIR and LC/MS analyses revealed that the extract contains various phytochemical constituents, including flavonoids, terpenoids, and other polyphenolic compounds, which contribute to its corrosion inhibition properties. The adsorption of the extract compounds on the steel surface followed the Langmuir adsorption isotherm, with a negative value of the standard free energy of adsorption, indicating a spontaneous and stable adsorption process involving both physisorption and chemisorption. SEM and XPS analyses confirmed the formation of a protective film by the adsorbed extract compounds, which acts as a barrier, preventing the direct contact between the aggressive solution and the steel substrate. The film also alters the wettability of the metal surface, making it more hydrophobic and further enhancing the corrosion inhibition efficiency. Quantum chemical calculations showed that flavonoids, particularly quercetin, contribute significantly to the corrosion inhibition performance due to their high reactivity, strong dipole moment, and stable adsorption on the Fe(110) surface. These findings provide valuable insights into the development of sustainable and eco-friendly corrosion inhibitors for the protection of metal structures in acidic environments.

Calcium-Based Metal-Organic Framework: Detection and Idiosyncratic Removal of Copper by Nano-Particle Deposition.

A novel calcium-based metal-organic framework (CaMOF@LSB) was designed and synthesized, exhibiting dual functionality for both selective detection and removal of Cu2+ ions from aqueous solutions. The framework's stability, including solvent and pH variations, was established with notable thermal resilience. Colorimetric Cu2+ detection (≥5 ppm) with a high capture capacity of 484.2 mg g-1 by CaMOF@LSB places this material among the few that ensure efficient colorimetric detection and high removal capabilities of Cu2+ ions. Batch adsorption experiments revealed pH-dependent behavior and competitive interactions. Langmuir and pseudo-second-order kinetics models aptly described adsorption isotherms and kinetics, respectively. Thermodynamic assessments confirmed spontaneous and endothermic adsorption. Mechanistically, nanoparticle deposition contributes to the Cu2+ uptake. CaMOF@LSB also exhibited one of the best removal behaviour of Cu2+ by means of oxide formation on the surface. Regeneration of CaMOF@LSB was achieved by simple sonication in 0.1 M aqueous NaOH solution. The recyclability was also tested up to 5 cycles, and it exhibited a small decrease in adsorption capacity observed across the cycles. This research presents a promising avenue for addressing heavy metal pollution using metal-organic frameworks, thereby offering potential applications in water purification and environmental pollution monitoring and remediation.

Preparation and Characterization of Lignin‐Based Activated Carbon by Rubidium Chloride Chemical Method

AbstractIn order to prepare carbon adsorbent materials, lignin was used as raw material and rubidium chloride as activator, activated carbon materials were prepared by chemical activation method, and its structure was characterized and its adsorption performance on methylene blue solution was investigated; the adsorption of crystalline violet dye was carried out at different temperatures, and the adsorption thermodynamics was studied. The results showed that: the specific surface area of the activated carbon was 433.32 m2/g, the pore volume was 0.2191 cm3/g, and the average pore size was 2.0222 nm; the adsorption value of methylene blue could reach 172.0 mg/g, and it could quickly and efficiently adsorb methylene blue solution; the adsorption effect on crystal violet solution was good, and the saturated adsorption amount at 40 °C was up to 279 mg/g, and the removal rate reached 93 %, belonging to the spontaneous adsorption thermodynamic reaction. The experiment proved that rubidium chloride can be used as an activator to activate lignin raw materials to prepare activated carbon samples, and can effectively adsorb dyes.