Langmuir Isotherm Research Articles

Elaboration of a new Activated Carbon derived from the Crown of Oak (ACOW) to removal the toxic Iodine: Kinetic, Isotherms modelling and Thermodynamics Study

ABSTRACT The current study aims to develop a new adsorbent material using oak crown and explore its effectiveness in removing I2 ions through a series of batch experiments. ACOW was characterised by zero charge (pHpzc) and FTIR spectroscopy. The impact of the initial I2 concentration (20-100 mg/L), temperature (25-55 °C), pH (2-14), adsorbent dosage (2-10 g/L), Stirring speed (100-900 rpm), particle size (100-2000μm) and contact time (0-30 min) on I2 adsorption was examined. The adsorption kinetic obeys the pseudo-second order model with a determination coefficient (R2) equal to 0.999. Adsorption follows the Langmuir equation well, with the best fit to the experimental data at equilibrium. A qmax value (= 103.606 mg/g) at 25°C and 120.773 mg/g at 55°C were eliminated under the optimised conditions, indicating homogeneous adsorption on the surface of the adsorbent. The thermodynamic parameters gave a negative free energy ΔGo (-3.445 to -5.629 kJ/mol), a positive enthalpy ΔHo (18.406 kJ/mol) and an activation energy Ea (= 22.599 kJ/mol), thus confirming the spontaneous and endothermic nature of adsorption of iodine on ACOW. The positive entropy ΔSo (0.0733 kJ/mol K) show increased randomness of the solid-liquid interface during the adsorption.

A novel adsorbent for the removal of chromium form aqueous solution by Acacia Fumosa seed shell activated carbon

In this experimental study, the activated carbon was synthesized by acid impregnation and digestion methods using Acacia Fumosa seed shell. The chromium removal was examined by altering the process conditions like carbon dose, chromium concentration, pH, and temperature and interaction time. The viability of the sorption process was examined using Freundlich and Langmuir equations. Evaluating the isotherm equations, the Langmuir equation shows more concordance compared with Freundlich equation. The feasibility of the adsorption was studied using Lagergren's kinetics equations of pseudo order equations of first and second order equations. Experimental investigation implies that the chromium removal follows pseudo-second order equation and it confines the investigation was subjected to time and concentration of chromium. The temperature effect was checked by chromium with Acacia Fumosa seed shell carbon. The Acacia Fumosa seed shell carbon alone was firmed using Gibbs free energy, enthalpy and entropy equations. The FTIR study of the synthesized activated carbon of before and after spectrum confirms the chromium adsorption. The SEM surface of the superficial layer change of carbon of initial and after chromium loaded state show viable change.

Adsorptive removal of anticarcinogen pazopanib from aqueous solutions using activated carbon: isotherm, kinetic and thermodynamic studies

Pazopanib, which is dangerous for aquatic environments due to its toxic and bioaccumulation potential, has been detected at different concentrations in oncology hospital wastewater, sewage, and surface waters. This study aimed to remove pazopanib from wastewater by activated carbon adsorption technique. The effect of the main variables such as initial concentration, pH of pazopanib solution, adsorbent dose, contact time of the phases, and temperature on the adsorption process was evaluated and the optimum adsorption conditions were determined. The experimental data were applied to Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich adsorption isotherm models to describe the adsorption behavior. The experimental data were applied to pseudo-first-order, pseudo-second-order, and intra-particle diffusion kinetic models to describe the adsorption kinetics. Isotherms were established in the 20–50 °C temperature range to study the adsorption equilibrium. According to the results, the highest removal efficiency of pazopanib (95.87%) was obtained at initial concentration (100 mg L−1), adsorbent dose (0.30 g L−1), temperature (20 °C), contact time (120 min) and pH (7.0). The adsorption kinetics was well described by the pseudo-second-order kinetic model (R2 = 0.9998) and the adsorption isotherm by the Langmuir model (R2 = 0.9999). In thermodynamic studies, the negative values of standard enthalpy (ΔH°), standard free enthalpy (ΔG°), and free entropy (ΔS°) indicate that the adsorption process is spontaneous and favorable, i.e. the disorder is reduced. These results indicate that the developed adsorption process can be efficiently and spontaneously applied for the removal of pazopanib from aqueous solutions.

Potential of ammonium adsorption of coal fly ash-based porous geopolymer granules

Abstract Porous geopolymer materials have been recently used in environmental remediation applications as adsorbents. This study is to investigate the NH4 + adsorption capacity of geopolymer activated from coal fly ash mixing with NaOH, Na2SiO3, and H2O2. The H2O2 with various ratios (0%, 4.5%, and 8.5%) were added into the fly ash pastes as blowing agents. The NH4 + adsorption capacity of these materials was examined concerning the effects of NaOH concentration, H2O2 contents, adsorbent particle sizes, dosages, and NH4 + concentration by batch adsorption test. The results show that adding 4.5% (G45) and 8.5% (G85) of H2O2 developed porous structures in geopolymer granules and their NH4 + adsorption capacity depends on their particle sizes and pore structures. In particular, geopolymer granules with 8.5% H2O2 exhibited higher NH4 + adsorption capacity than lower content of H2O2 in case of particle size of 3.0-8.0 mm. However, pulverized geopolymer still demonstrated the greatest NH4 + adsorption capacity. In addition, both granules G45 and G85 demonstrated a well-fit (R2 = 0.97-0.99) with Langmuir and Freundlich isotherms. The maximum NH4 + adsorption capacity of G85 was 19.86 mg/g, which indicated the NH4 + adsorption potential of porous geopolymer granules generated from waste materials such as coal fly ash.

Thermodynamics, kinetic study and equilibrium isotherm analysis of cationic dye adsorption by ternary composite

This article investigates the kinetics, equilibrium, and thermodynamics of brilliant green dye adsorption on Fe3O4/CdS/MWCNTs. The effects of adsorbent dosage (0.01–0.06 g), contact time (1–120 min), temperature (278, 288,298 and 308 K), ionic strength (NaCl and CaCO3 salt), and initial solution pH (4,6,7, and 10) were all studied in relation to the adsorption of BG dye. Langmuir (R2 = 0.86883), Temkin (R2 = 0.96323) and Freundlich (R2 = 0.96958) and isotherms were fitted to describe the equilibrium of BG adsorption process. Isothermal models showed that BG adsorption was a favorable process on ternary composite Adsorption kinetics were well fitted by Pseudo-second order kinetic model (R2 = 0.99396). The thermodynamic parameters ΔH° = −0.0277 kJ.mol−1 and ΔS° = −60.9031 J mol−1.k−1 indicate endothermic and spontaneous adsorption process, (ΔG° > 0) non-spontaneous, and exothermic. Five adsorption/desorption cycles were demonstrated by the adsorbents’ high reusability.

Green and eco-friendly scalable synthesis of chitosan-carbon nanocomposite for efficient dye removal

The integration of activated carbon with chitosan (CS) for dye removal offers a multitude of benefits, making this hybrid material a promising and efficient solution for water purification. Activated carbon was synthesized from fruit wastes and then mixed with CS for the preparation of chitosan‑carbon nanocomposite (CSCNC) using ball milling technique. X-ray diffraction and ATR-FTIR technique affirmed the preparation of CSCNC. Additionally, the findings obtained from TEM and SEM analysis signifying the deposition of activated carbon onto the surface of CS. The majority of particle size and polydispersity index (PdI) for CSCNC was found to be 162.8 nm and 0.483, respectively as displayed from DLS technique. The current research work was examined the adsorption and desorption behaviors of Methylene Blue (MB) using CSCNC. Adsorption experiments reveal a time-dependent process characterized by an initial rapid phase and gradual approach to equilibrium, with the pseudo-second-order kinetics model providing the best fit. The adsorption capacity exhibited a rising pattern as the pH increased, reaching its peak value of 912.4 mg/g. Both Langmuir and Freundlich isotherm models explained the equilibrium relationship between MB and the nanocomposite, offering insights into maximum adsorption capacity and surface characteristics. Desorption studies explored the nanocomposite's regenerative potential under varying conditions. The findings contributed to the sustainable design of water treatment technologies, emphasizing the nanocomposite's efficiency, scalability, and regenerative capabilities.

Studies of hybrid ceria polypyrrole CPP-2 composite for effective defluoridation from potable water

Drinking water sources should eliminate fluoride ions, as they pose a serious threat to human health. By using in situ oxidative polymerization and Pechini’s method of CeO2 (CO), a new hybrid composite, CPP-2, was designed. Several physicochemical techniques were used to establish the properties of the adsorbent in its as synthesized state. The F- ions were removed from effluent using the hybrid composite adsorbent. The adsorption isotherm model was best represented by the Langmuir adsorption isotherm model. It yielded a maximum adsorption capacity of 351.8 mg/g at an optimal pH of 4 ± 0.2 at room temperature. The pseudo second order model best describes the adsorption process according to kinetic results. To get a detailed understanding of the fluoride adsorption mechanism, FTIR and XPS spectra are analyzed. Anionic exchange of the hydroxyl groups with F- ions and electrostatic attractions of the protonated hydroxyl on the surface of the adsorbent, as well as the nitrogen atoms of the amino groups from the polypyrrole (PP) moiety with the F- ions, were responsible for the process. The enthalpy change (ΔH° = +6.32 KJ/mol) and Gibbs free energy (ΔG° = -8.95 KJ/mol) were obtained from the thermodynamic data, which demonstrated the spontaneity, feasibility, and endothermic nature of adsorption. It had a great potential for defluoridation from groundwater at a pH level below the thresholds specified by the WHO and could withstand up to five cycles of adsorption and desorption. The overall results exhibited that CPP-2 has an enormous promise for defluoridation.

Eco-friendly Corrosion Inhibitor of Q235 carbon steel in 1.0 M HCl by Isatin/Chitosan Schiff Base

This study presents the synthesis of an eco-friendly and green Schiff base, namely Isatin-Cs Schiff base corrosion inhibitor for Q235 carbon steel in 1.0 M HCl corrosion solution. Fourier-transformed infrared FT-IR and 1H NMR was utilized to characterize the prepared Isatin-Cs Schiff base corrosion inhibitor. The inhibition performance in 1.0 M HCl solution was investigated via classic weight loss at various temperatures, potentiodynamic polarization (PPD), and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy SEM, X-ray photoelectron spectroscopy XPS, and water contact angle methods are used to analyse the surface morphology of Q235 carbon steel. The polarization measurements indicate that the corrosion inhibitors act as mixed type. Moreover, the weight loss studies show that the efficiency of inhibitor increases with the concentration of inhibitor to reach a maximum efficiency of 88.4% with 250ppm at 25°C. Nevertheless, increasing temperature has negative effect on the efficiency of the Isatin-Cs inhibitor. The Langmuir isotherm Unveil that Isatin-Cs adsorption on Q235 carbon steel is mediated via physi/chemi-sorption. Based on SEM and XPS analyses Isatin-Cs forms stable protective film on Q235 carbon steel. The DFT results complemented the experiments results, both observed the effectiveness of inhibitor adsorption.

Super-efficient removal of yellow 161 anionic dye from water by activated carbon based on coffee grounds

The study evaluates the effectiveness of activated carbon derived from coffee grounds (ACcg) in removing Reactive Yellow 161, a pollutant from the textile industry. The properties of ACcg are analyzed by various techniques such as FTIR, SEM, EDS and X-ray diffraction. In addition, physico-chemical analyses, such as moisture content, ash content, volatile matter, iodine value and zero charge point (pHpzc), were carried out on the prepared ACcg. The Box-Behnken Design (BBD) scheme combined with the Response Surface Method (RSM) is used to optimize adsorption variables. Results show high microporosity of ACcg, adsorption kinetics fitted to pseudo-first order and Langmuir isotherm consistent with experimental data. Thermodynamic parameters indicate spontaneous and exothermic adsorption behavior. Residue analysis and ANOVA confirm a high adsorption capacity of ACcg (97.67 %) at an initial concentration of 20 ppm Reactive Yellow, with an ACcg mass of 1 g/L and a pH of 3. The chosen model is validated for this application.

Green electrospun Fe-based MOFs incorporated polyvinyl alcohol/carboxymethyl chitosan nanofibrous membranes for enhanced adsorption of tetracycline hydrochloride

Tetracycline hydrochloride (TCH) removal from wastewater has drawn much attention recently, although it still remains challenging. Herein, Fe-based metal-organic frameworks (MOFs) incorporated nanofibrous membranes were prepared by green electrospinning and applied as adsorbents to remove TCH. The presence of MOFs noticeably improved specific surface area of the nanofibrous membranes, and adsorption capability increased with the amount of MOFs within membranes. As the temperature increased, the amount of TCH that was adsorbed continuously reduced, and the maximum adsorption capacity (248.5 mg/g) was attained at 273 K. The adsorption behavior of the nanofibrous membranes followed Langmuir isotherm model and pseudo-second-order kinetic model. Thermodynamic parameters suggested that the adsorption process was spontaneous and exothermic. A series of interactions between the membrane and TCH, such as pore filling, coordination bonding, π-π interaction, hydrogen bonding interaction and electrostatic interaction, combined to enhance the adsorption performance. Good stability and adsorption capability were demonstrated by the nanofibrous membranes, suggesting that they could be used for effective and affordable water purification.

Innovative potassium hexacyanoferrate intercalated into layered double hydroxide adsorbent for efficient cesium removal from seawater

Effective radioactive wastewater treatment technology is essential to ensure the sustainable development of nuclear energy. Here, the potassium ferrocyanide (HCF) intercalating with layered double hydroxide (LDH) (HCF@LDH) was successfully synthesized by coprecipitation method for selective cesium (Cs) removal from seawater. Characteristics of the adsorbent, and adsorption performance under different environmental conditions including Cs+ ion selectivity, and underlying adsorption mechanism were systematically investigated. The experimental results demonstrated that the adsorption capacity of HCF@LDH was 52.08 mg/g and it effectively removed 100 % of Cs+ from up to 200 mg/L Cs solution within 1 h under an optimal pH of 6.0–10.0. Moreover, the adsorbent displayed high selectivity towards Cs+ even in seawater and more than 90 % of Cs+ was removed from seawater and the highest cesium removal capacity from seawater was 44.64 mg/g. Both the Langmuir isotherm model (R2 = 0.997) and the pseudo-second-order kinetic model (R2 = 0.999) provided a good fit for the adsorption data signifying the adsorption process is homogeneous and formed monolayer through chemisorption. Furthermore, the reusability analysis exhibited this adsorbent was recycled and reused for at least 5 cycles without losing its original adsorption performance. The physicochemical analysis of the HCF@LDH proved that K4Fe (CN)6 successfully intercalated onto LDH and cation exchange between K+ and Cs+ played an important role in effective Cs adsorption. More specifically, the interstitial spaces of the hexacyanoferrate crystals facilitate the cation exchange process. The findings of this study demonstrate that HCF@LDH is a unique, highly effective, and selective adsorbent for Cs+ from complex seawater.

Removal of congo red and malachite green from aqueous solution using ternary GO/Bi2O3/MgO materials by co-precipitation method

The present work describes the preparation of Bismuth oxide and magnesium oxide modified with graphene oxide (GO/Bi2O3/MgO) using the co-precipitation method for the elimination of malachite green (MG) and congo red (CR) dyes from aqueous solution. The synthesized GO/Bi2O3/MgO materials were analyzed by using FTIR, SEM, XRD, EDX and EDS. The batch experiment was aimed to investigate the adsorption process by varying various parameters of optimum value for CR and MG dye adsorption such as adsorbent dosage was 100 mg, contact time was 30 min, stirring speed was 250 rpm, initial dye concentration was 30 mg L−1 and pH was 6.5. From experimental data, we concluded that for elimination of MG and CR dye with higher coefficient value (R2) was best fitted with the Langmuir isotherm model. The maximum adsorption capacity was observed to be 45.454 mg/g for MG and 58.823 mg/g for CR, respectively. The mechanism of the adsorbent and both the dyes were explained by electrostatic interaction, π-π interaction, and hydrogen bonding. To check the stability of the GO/Bi2O3/MgO materials, we performed the reusability study using various solvents like methanol, ethanol, water, sodium hydroxide and acetone. Among various solvents, NaOH has shown maximum desorption of both dyes.

Hydroxyapatite derived from eggshell embedded on functionalized g-C3N4 for synergistic extraction of U(VI) from aqueous solution

In this paper, we report hydroxyapatite derived from egg-shell biowaste embedded on diglycolamic acid functionalized graphitic carbon nitride nanocomposite (abbreviated as HAp@D-gCN). The compositional and morphological characteristics of HAp@D-gCN were evaluated using scanning electron microscope, X-ray diffraction, BET, FTIR techniques and surface charge using zeta potential measurement. The sorption of U(VI) species on HAp@D-gCN was investigated through batch studies as a function of pH, contact time, initial U(VI) concentration, adsorbent dosage and ionic strength. The adsorption of U(VI) onto HAp@D-gCN was confirmed by FTIR, XRD and EDS elemental mapping. Adsorption kinetics follow pseudo second order model and it attains equilibrium within 20 min. Adsorption isotherm data correlates well with Langmuir isotherm model with a maximum sorption capacity of 993.6 mg of U(VI) per gram of HAp@D-gCN at 298K. U(VI) can be leached from the loaded adsorbent using 0.01 M Na2CO3 as desorbing agent and its sorption capacity remains unaffected even after 4 adsorption-desorption cycles. Hence, the present study reveals that HAp@D-gCN nanocomposite could serve as an environmental friendly material with potential application in environmental remediation.

Sodium alginate/banana peels/reduced graphene oxide nanocomposite beads for effective removal of copper and nickel from aqueous solutions

The use of naturally derived nanocomposite beads to remove nickel and copper is gaining more attention due to its relative abundance, low toxicity, and strong affinity toward heavy metals. Most previous studies focus on removing single heavy metals using developed nanocomposite beads. This work prepared sodium alginate/banana peels/reduced graphene oxide nanocomposite beads through simple precipitation using banana peels, reduced graphene oxide, and sodium alginate. The formed nanocomposite beads were characterized and evaluated for the adsorption of nickel and copper from the aqueous phase at neutral pH. The Langmuir isotherm suggests the homogenous adsorption of metals on the surface of the bead. The maximum removal capacity is 85.32 mg/g and 95.79 mg/g for nickel and copper, respectively. This study provides new insight into utilizing banana peels, reduced graphene oxide, and sodium alginate for toxic metal remediation to overcome pollution problems.

Fabricating nepheline syenite-chitosan composite for heavy metals uptake: Mechanism insight via statistical physics modeling

Given the substantial costs associated with conventional wastewater treatment methods, researchers are increasingly exploring mineral compounds for their cost-effectiveness, widespread availability, and efficiency. In this study, nepheline syenite, an alkaline igneous rock, was selected among these compounds. The research investigates the single and binary adsorption of heavy metals (Ni(II) and Cd(II)) from synthetic and electroplating industrial effluents using a nepheline syenite-chitosan composite (NS-CS). The physical and chemical properties of the adsorbents were characterized using XRD, XRF, FT-IR, BET, and SEM analyses. The study examined the effects of solution acidity, contact time, initial concentration, and adsorbent dosage to determine the optimal conditions for the uptake of Ni(II) and Cd(II). The isothermal data were best described by the Langmuir isotherm model, with NS-CS showing adsorption capacities of up to 40.48 mg/g for Ni(II) and 41.79 mg/g for Cd(II). Additionally, the competitive adsorption of nickel and cadmium in the binary system was more accurately described by the modified Freundlich equation. Kinetic data were best fitted by the pseudo-second-order model. Thermodynamic analysis indicated that the adsorption of both ions was endothermic and nonspontaneous. Statistical physics modeling was employed to elucidate the adsorption mechanism of heavy metals on the NS-CS composite. The single-layer model with one energy level provided the most precise fit to the experimental data. Using this model, key factors were calculated, revealing that the adsorption energies for both Ni(II) and Cd(II) ions were below 20 kJ/mol, suggesting that the adsorption process is likely physical in nature.

Resourceful exploitation of sedimentary clay: Designing a dual-chambered borosilicate glass reactor system for the efficient treatment of malachite green and phenol through SCRT adsorption and 5%Fe@SRCT catalysis via CWPO, with evaluation of seed germination and fish survival.

This study presents an innovative double-walled borosilicate glass reactor system for the efficient treatment of liquid and gaseous wastewater. This reactor system allows precise temperature control, continuous pH monitoring, and controlled dosing of reagents to optimize reaction conditions. Detailed characterization was carried out by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), BET (specific surface area) analysis, point of zero charge (PZC), and scanning electron microscopy (SEM) for the SCR, SCRT, and 5%Fe@SCRT materials. For Malachite Green adsorption, SRCT demonstrated a maximum adsorption capacity of 39.78 ±0.5mg/g using the Langmuir isotherm model and followed pseudo-second-order kinetics. Optimum conditions for adsorption were found to be: an initial concentration of 50 ppm, an adsorbent dosage of 1g/l, a pH of 8.5, and a temperature of 50°C. For the catalytic oxidation of phenol, 5%Fe@SRCT achieved a remarkable removal rate of 99.9±0.1% under optimum conditions (50 ppm phenol, 1g/l catalyst dosage, pH3.5, H2O2 concentration 8.7mM, and temperature 70°C). Intermediates identified during the reaction included hydroquinone, benzoquinone, catechol, and resorcinol, with degradation occurring over a 60-minute reaction period. The 5%Fe@SCRT material showed excellent reusability in the removal of phenol by catalytic oxidation, with no significant loss of efficiency over three cycles, while the SRCT underwent three cycles of regeneration for the adsorption of Malachite Green. Scavenger tests confirmed the involvement of hydroxyl radicals in the catalytic oxidation process. In addition, fish survival tests after catalytic oxidation of phenol by 5%Fe@SRCT showed no impact on fish, underlining the environmental safety of this process. In addition, germination tests after decolorization of MG by SRCT demonstrated a good effect with no negative impact, reinforcing the ecological value of this innovative technology. These results highlight the innovative use of SCRT and 5%Fe@SCRT as versatile materials for environmental remediation, exploiting their effective adsorption capacities and efficient catalytic oxidation performance within the proposed double-walled borosilicate glass reactor system. PRACTITIONER POINTS: The study demonstrates the effectiveness of an innovative reactor system employing SRCT adsorbent and Fe@SRCT catalyst for efficient removal of malachite green and phenol from wastewater. Environmental impact assessment, including seed germination and fish survival evaluation, validates the method's eco-friendly potential. Implementation of this approach could significantly contribute to sustainable water treatment practices.

Synthesis, characterization and As(III) scavenging behaviours of mango peel waste loaded with Zr(IV) ion from contaminated water

Raw mango peel (RMP) was first saponified to yield saponified mango peel (SMP), which was then loaded with Zr(IV) ions to form a biosorbent for As(III) scavenging.The biosorption behaviors and mechanisms of As(III) scavenging using RMP and Zr(IV)-loaded saponified mango peel (Zr(IV)-SMP) were investigated batchwise. The As(III) scavenging efficiency of RMP increased from 20.13 % to 87.32 % after Zr(IV) loading. Optimum contact time of 6 h has been investigated for As(III) scavenging by Zr(IV)-SMP, and the data on kinetics is well fitted to the pseudo-second-order (PSO) model. Similarly, isotherm data of Zr(IV)-SMP fitted well to the Langmuir isotherm model with the maximum As(III) scavenging potential of 45.52 mg/g. Chloride (Cl−) and nitrate (NO3−) have negligible influence on As(III) scavenging, but sulphate (SO42−) interferes significantly. The exhausted Zr(IV)-SMP could be easily regenerated by treating with 2MNaOH. A mechanistic study indicates that As(III) scavenging is primarily contributed to electrostatic interaction and ligand exchange, which is confirmed from both instrumental and chemical characterizations techniques. Tubewell underground water polluted with a trace amount of arsenic (98.63 μg/L) could be successfully lowered down to the WHO standard (10 μg/L) by applying a small amount of Zr(IV)-SMP. Therefore, the Zr(IV)-SMP investigated in this work can be a low-cost, environmentally benign, and promising alternative for scavenging trace levels of arsenic from contaminated water.

Exploring of new Poly(Thiourea-Amide) as a prospective bismarck Brown Y dye adsorbent: Synthesis via ultrasound irradiation, isotherms, kinetic, thermodynamic, and DFT studies

In this work, a facial ultrasound technique was employed to synthesize poly (N1-((6-aminopyridin-2-yl)carbamothioyl)-N3-carbamothioylisophthalamide) (PTUA) as a new polymer from a condensation reaction of isophthaloyl diisothiocyanate and 2, 6-diaminopyridine. Different techniques were utilized to identify the chemical structure of the synthesized polymer including FTIR spectra, 1HNMR spectra, thermal gravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), and field emission scanning electron microscopy (FESEM). The capability of the synthesized polymer to adsorb Bismarck brown Y (BBY) dye from an aqueous solution was analytically evaluated. Several effective parameters on the adsorption process including contact time, pH, dye concentration, adsorbent dose, and temperature were extensively investigated. The adsorption process was found to be completed with a contact time of 45 min. The results indicated that the optimal adsorption pH was 8 with removal efficiency of 85.331 % and the adsorbed amount of BBY dye increased when the temperature was increased. The adsorption isotherms analysis revealed that the Langmuir model with a correlation coefficient (R2 = 0.9982) was the most relevant to describe the adsorption process compared with the Freundlich model (R2 = 0.9863). By applying the Langmuir isotherm, the maximum adsorption capacity was obtained with a value of 132.39 mg/g. The study of adsorption kinetics showed that the adsorption model of BBY dye onto the polymer surface significantly correlated with a pseudo-second-order model. Based on the thermodynamic studies, the calculated ΔG was negative, ΔH was endothermic, and ΔS was positive, verifying the adsorption process is spontaneous. The desorption percentage of BBY dye was calculated with a value of 81.574 % utilizing methanol as an optimal solvent. The density functional theory (DFT) approach was applied to acquire good understanding for the adsorption process.

Study on corrosion inhibition of carbon steel by imidazolylium-based ionic liquids in chlorine dioxide water disinfection

Chlorine dioxide (ClO2), recognized for its high efficiency, broad-spectrum capabilities, and safety, is extensively utilized in water disinfection processes. Possessing strong oxidizing properties, prolonged exposure to ClO2 can lead to irreversible corrosion of metals. To mitigate the ClO2-induced corrosion on steel, the corrosion inhibition performance and underlying mechanism of BMIMAc and BMIMBr on 20 steel and Q235 steel in ClO2 solutions ranging from 2.5 to 10mg/L is systematically studied by static weightlessness experiments, potentiodynamic polarization curve experiments, SEM, EDS, DFT calculations, and MD simulation. The findings demonstrate that both ionic liquids significantly impede corrosion, where BMIMAc outperforms BMIMBr in terms of corrosion inhibition efficacy. These inhibitors exhibit effective adsorption onto the carbon steel surface, conforming to the Langmuir isotherm model. Both ionic liquids are cathodic inhibitors. They can adsorb on the metal surface in an approximately parallel manner and their imidazole ring can form a coordination bond with the metal, leading to the formation of an adsorbent membrane that prevents further contact of the metal with ClO2, thus reducing the degree of oxidation and retarding the corrosion process.

Empirically extending 1D Child–Langmuir theory to a finite temperature beam

Empirically extending 1D Child–Langmuir theory to a finite temperature beam