Search

Combining Deep-UV second harmonic generation spectroscopy with molecular simulations, we confirm and quantify the specific adsorption of guanidinium cations to the air-water interface. Using a Langmuir analysis of measurements at multiple concentrations, we extract the Gibbs free energy of adsorption, finding it larger than typical thermal energies. Molecular simulations clarify the role of polarizability in tuning the thermodynamics of adsorption, and establish the preferential parallel alignment of guanidinium at the air-water interface. As a polyatomic cation, guanidinium represents one of the few examples of a positively charged species to exhibit a propensity for the air-water interface. As such, these results expand on the growing body of work on specific ion adsorption. [ABSTRACT FROM AUTHOR]

Herein, bentonite-chitosan nanocomposite (BT-CS nanocomposite) has been synthesized and exploited, for the first time, as a dual adsorbent for the removal of both of an anionic (Reactive Red 195 (RR)) and a cationic (Crystal Violet (CV)) dyes from aqueous solution. The adsorption behavior of the exploited nano-adsorbent towards the dyes under investigation were scrutinized in batch experiments as a function of several factors such as contact time, pH value, adsorbent dose, initial dye concentration, stirring rate, and temperature. The prepared nano-adsorbent achieved superior removal efficiency of 99.4 and 99.8% within 20 min at optimum pH value of 3 and 5 using adsorbent dose of 0.1 g and 0.08 g at room temperature for RR and CV dyes, respectively. Also, the developed nano-adsorbent affords higher removal efficiency of CV dye against broad pH range of 2–9. Moreover, the developed nano-adsorbent achieved significant antibacterial behavior against various pathogenic bacterial and record clear inhibition zone of 21 mm against Escherichia coli (ATCC 8739). Langmuir adsorption model and pseudo-second order adsorption can fully depict the BT-CS nanocomposite adsorption properties for both of RR and CV dyes. Furthermore, thermodynamic studies showed that the process was spontaneous and endothermic with increased in randomness. The prepared dual adsorbent in this study exhibited reversible dyes adsorption with an excellent regeneration efficiency. Whereas, after 5 successive adsorption–desorption cycles, the adsorption efficiency of the synthesized adsorbent was 99% and 98% for RR and CV dyes, respectively, affirming its capability to economically decontaminate the industrial wastewater comprising RR and CV dyes. [ABSTRACT FROM AUTHOR]

Satureja montana essential oil is a natural substance able to inhibit the growth of several pathogens. This antimicrobial effect is often attributed to its ability to penetrate cellular structures and disrupt them. Although these properties are recognized as playing a key role in the mechanism of action of this substance, many unresolved issues still exist, and fundamental studies focused on such aspects are scarce. In this framework, we investigated the interaction of SEO with lipid monolayers, which represent simplified models of cell membranes, using the Langmuir monolayer technique, complemented by fluorescence anisotropy and differential scanning calorimetry on lipid bilayers. By focusing on packing conditions that approximate those of biological membranes and using lipids with different polar heads and structures, such as the ones occurring in bacterial membranes, we aim to clarify the effect of this essential oil on the lipid membrane. Our results show that Satureja montana essential oil consistently manages to insert into the membrane and interfere with the lipid–lipid interactions, thereby altering the lipid packing and significantly increasing the membrane fluidity, depending on the oil concentration and the nature of the lipid. [ABSTRACT FROM AUTHOR]

In this study, Adsorption characteristics of uranium from nitrate media onto a commercially accessible strong cation exchange resin, Marathon C, were investigated. The characteristics of Marathon C, before and after adsorption of uranium, were determined using scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). The influence of the different parameters, which may affect the process of uranium adsorption process from synthetic solutions and applying on real sample from uranium purification unit, had been tracked. Specifically, impacts of initial uranium concentration (40–300 mg/L), PH (1–8), phase ratio (0.2–1.2 g/L), contact time (2–360 min.) and temperature (& 25–50°C) on uranium removal, were studied. In addition, the sorption kinetics and equilibrium parameters were assessed. At the optimum conditions, the adsorption capacity of uranium at PH 4, 1 g Marathon C/L and 120 min were found to be nearly 131.58 mg g−1 at room temperature (& 25°C). The kinetics and isotherm studies could show that the uranium adsorption onto Marathon C is following the models of pseudo-second-order and Langmuir isotherm, respectively. The thermodynamic parameters had indicated that the adsorption of uranium is an exothermic and spontaneous process (∆H = −64.27 ± 0.01, ∆G = −22.57 ± 0.02). The detected results of uranium adsorption could reveal that Marathon C is a suitable material for adsorption of uranium from nitrate media and applying on real sample from uranium purification unit. [ABSTRACT FROM AUTHOR]

Sodium-rich zeolite A and zeolite X (FAU-type) samples were synthesised from LD-slag via fusion-assisted hydrothermal treatment. The physicochemical and thermal stability of the prepared samples were examined with the help of various characterisation techniques, namely, Fourier Transform Infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and thermogravimetric analysis (TGA) analysis at three different pH conditions and treatment time. Moreover, the sustainability of the crystalline phase and the corresponding zeolite network was evaluated from XRD, FTIR, TGA and Field-Emission Scanning Electron Microscopy (FESEM) analysis. Zeolite A depicts a unique cubical structure and is thermally more stable as compared to zeolite type-X. Also, zeolite A showed the highest dye removal efficiency of 98.13%, as compared to 94.47% for zeolite X, along with equilibrium sorption capacities of 25.30 and 23.57 mg g−1, respectively. In addition, the study proposes that both the synthesised adsorbents are effective and economically sustainable for cationic methylene blue adsorption. Furthermore, methylene blue adsorption was regulated by a multistage diffusion process that agreed with a pseudo-second-order kinetic model (R2 = 0.999 and 0.996 for A- and X-type zeolites). The Langmuir isotherm model best suited the equilibrium data, with monolayer adsorption capacities of 20 and 25.40 mg g−1, respectively. [ABSTRACT FROM AUTHOR]

Acne vulgaris is one of the most common dermatological diseases and is strongly connected with the pathological growth of the Cutibacterium acnes. More than half of the cultures of this bacterium are resistant to antibiotics, resulting in the proposal of the use of antibacterial peptides as an alternative to traditional antibiotics. Ascorbic acid (AA) and its antioxidant properties may ally in acne therapy. The aim of this study was to determine the influence of the selected antibacterial peptides in the presence of ascorbic acid and 3-O-ethyl-ascorbic acid (EAA) on the properties of the monolayer formed by phosphatidylinositol. Studies of the properties of the phosphatidylinositol monolayer were carried out using the Langmuir–Wilhelmy balance. The recorded compression isotherms, hysteresis loops, and surface pressure values recorded at specific time intervals were evaluated to assess the influence of ascorbic acid and its derivatives in the presence of antimicrobial peptides on the stability and organization of phosphatidylinositol monolayers. The addition of AA to the subphase caused a faster phase transition at over 60 Å2/molecule and significantly reduced the plateau surface pressure by about 20% in most of the systems tested. The studied monolayers were found to be in the expanded liquid state (40.23–49.95 [mN/m]) or in the transition between the expanded and condensed liquid phase (51.47–60.98 [mN/m]). Compression and decompression isotherms indicated the highest flexibility of the systems at 20 °C and 25 °C. The surface pressure versus time dependence indicated the stability of the phosphatidylinositol monolayer with 3-O-ethyl–ascorbic acid and antimicrobial peptides up to 35 °C. [ABSTRACT FROM AUTHOR]

In this study, we aimed to develop a mathematical description of the process of phosphate sorption on Rockfos® material using the Langmuir isotherm and determine the basic parameters for modeling this process. The Rockfos® material was formed through the thermal treatment of opoka at 980 °C and is highly reactive due to its significant calcium and silicon compound content. This study included an evaluation of the phosphate retention efficiency on the material as a function of the phosphate concentration in the initial solution (0.5 mg/L, 1.0 mg/L, and 2.0 mg/L), sorbent grain size (1.0–1.6 mm, 1.6–2.5 mm, and 2.0–5.0 mm), and process temperature (5 °C, 10 °C, 15 °C, 20 °C, and 25 °C). It was found that an increase in the process temperature and the phosphate concentration in the solution favored sorption, while the effect of the sorbent grain size was ambiguous. It was determined that sorption can be described well using the Langmuir linearization of the Langmuir model. Thermodynamic analysis and the separation coefficient suggest that phosphorus sorption on Rockfos® material is primarily based on chemisorption, and the process is endothermic and spontaneous over the entire temperature range. The determined parameters of the tested material, especially the qmax (maximum sorption capacity), provide a basis for the design of a filter for removing phosphate from wastewater, assuming that the load is equal to the inflow to the filter and adheres to the specified requirements for treated wastewater. [ABSTRACT FROM AUTHOR]

Abstract\nSIGNIFICANCE STATEMENTHexavalent chromium (Cr(VI)) poses a significant ecological threat due to environmental pollution. The urgent need for an economically viable solution to remove Cr(VI) and restore ecological balance is evident. This study explores the adsorption isotherms of Cr(VI) uptake by newly isolated B. bassiana SSR5 dead fungal biomass. The batch uptake experiments, conducted under controlled pH and temperature conditions, reveal that dead fungal biomass from B. bassiana has an outstanding ability to adsorb Cr(VI). The optimal adsorption occurs at pH levels of 1 and ≤1.5, achieving a maximum capacity of 113.2 mg per gram of dry weight at an initial concentration of 300 mg/L. The adsorption capacity is strongly influenced by the solution pH, with peak values noted at pH 1.0. Conversely, temperature variations show minimal impact on the uptake capacity. All adsorption isotherms exhibit a strong correlation with the standard Langmuir equation, indicating a monolayer adsorption mechanism. The kinetic profile illustrates a rapid uptake process, achieving equilibrium within 30 min, suggesting the involvement of chemisorption. The process primarily involves ion exchange and electrostatic interactions between positively charged sites on the fungal biomass and negatively charged Cr(VI) ions at lower pH levels, facilitating the reduction of Cr(VI) to Cr(III) and enhancing adsorption. This study underscores the potential of B. bassiana dead fungal biomass as an effective biosorbent for Cr(VI) removal from wastewater and tannery effluent. The intriguing mechanism and the pH effect on the conversion of Cr(VI) to Cr(III) ions by the fungal cell wall warrant further exploration.Hexavalent chromium [Cr(VI)] pollution poses a significant ecological threat, and our study shows the remarkable efficiency of dead fungal biomass derived from Beauveria bassiana in adsorbing Cr(VI). The findings underscore the pH-dependent nature of Cr(VI) conversion to Cr(III) by B. bassiana dead fungal biomass, revealing heightened adsorption efficacy in acidic environments, particularly optimal at pH levels ≤1.5. This adsorption process is mediated through biosorption coupled with a redox mechanism. Importantly, the results unequivocally support the conformity of Cr(VI) adsorption by dead fungal biomass to the Langmuir isotherm model, implying a monolayer adsorption mechanism. Moreover, the implication of pseudo-second-order kinetics indicates the involvement of chemisorption, emphasizing the substantial chemical interactions between Cr(VI) ions and the fungal biomass surface. These observed kinetic parameters offer pivotal insights into the adsorption mechanism, establishing the potential of B. bassiana dead fungal biomass as a highly promising biosorbent for the removal of hexavalent chromium from aqueous solutions. Further investigations into application potential and optimization of operational parameters are imperative to fully exploit its adsorption capacity. [ABSTRACT FROM AUTHOR]

The synthesis of metal oxide nanoparticles has gained much attention due to its wide range of applications in the field of industrial, chemical, and biological applications. These metallic nanoparticles have been developed for azo-dye removal, but they are limited for ecofriendly and cost-effective processes. The main objective of this study is to focus on the synthesis of Fe2O3-nanoparticles by green route followed by its application in the dye removal process from wastewater. In this approach, the active iron oxide nanoparticles (Fe2O3-NPs) were produced successfully using Camellia sinensis and Aloe barbadensis leaf extract. The prepared nanoparticles were characterized using SEM, XRD, FTIR, and UV–Vis spectroscopy, As per results, the NPs effectively degraded both the azo-dyes from the aqueous solution with 70–80% removal efficiency in 40–45 min under optimum conditions. Moreover, the color change in the solution indicated the formation of Fe2O3-NPs. The absorption peak was observed at 275 nm and 270 nm for Aloe barbadensis leaf extract and Camellia sinensis extract, respectively. The FTIR peak at 553.63 cm−1 indicates the presence of Fe2O3 NPs along with other peaks at 2853.3 cm−1 for O–H stretching in carboxylic acid; at 3404 cm−1 due to the O–H group present in the extract, broad peak of 3406 cm−1 shows –OH group of carbohydrates and phenols along with a peak at 2891 cm−1 for asymmetrical and symmetrical C-H stretching. The results of XRD and SEM indicate the homogeneity, shape, and size of NPs, which were spherical and cubic. The size of the particles ranged between 80 and 100 nm for both types of NPs prepared using the extracts. The Langmuir and Elovich isotherms were used to analyze adsorption behavior. The pseudo-first-order and pseudo-second-order kinetic approaches were used and found satisfactory for both approaches. An extensive discussion has been made in light of the experimental data and results obtained. [ABSTRACT FROM AUTHOR]

This study examined the corrosion inhibition of 304 stainless steel (304 SS) with fucoidan in 3.5% NaCl solution using both chemical and electrochemical methods, including mass loss as a chemical method and electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP) as an electrochemical method. The fucoidan compound was verified and characterized by Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy, and morphology characteristics. The PP curves indicate that fucoidan was an effective corrosion inhibitor for 304 SS in 3.5% NaCl solutions, which indicates that the compound is a mixed-type inhibitor. It was shown that by adding the fucoidan inhibitor, the corrosion potential (Ecorr) and Tafel lines were slightly shifted. With the compound added, the value of the double-layer capacitance was reduced. In the case of 200 ppm, it reached maximum efficiencies of 81.7%. After studying its adsorption behavior on 304 SS, the Langmuir isotherm and chemical adsorption were concluded. It was necessary to compare the theoretical computations with the experimental findings using both density functional theory (DFT) and Monte Carlo simulations (MC). [ABSTRACT FROM AUTHOR]

The inhibitory effect of A. orientalis L. extract (AO) on aluminum corrosion in a 1.0 M HCl solution was investigated utilizing weight loss, electrochemical polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The results show that AO is a potent inhibitor in an acidic environment, and that the inhibition potency increases with concentration. Temperature investigations showed that, in an acidic medium, the efficiency decreased, increased, and then decreased as the temperature rose. Adsorption isotherms from Freundlich, Temkin, El Awady, and Redlich–Peterson (R-P) approximated the inhibitor's adsorption properties. For the inhibitory behavior, a physical and chemical adsorption mechanism is proposed. The adsorption process's thermodynamic parameters (Ea, ΔH*, and ΔS*) were determined and explained. The inhibitor, AO, was identified as a mixed-type (anodic and cathodic) inhibitor based on polarization studies. According to the SEM findings, the inhibitor partially covers the metal surface, providing it with a respectable level of protection. The weight loss, electrochemical polarization, EIS, scanning electron microscopy (SEM), and quantum chemical calculations show a strong agreement, indicating that the AO extract is a highly effective inhibitor of aluminum in an acidic solution. [ABSTRACT FROM AUTHOR]

Adsorption is a simple, inexpensive, and common practice in water purification and recycling technologies. Therefore, researchers investigated various approaches and materials to develop low-cost adsorbents. Furthermore, researchers investigated using local materials to develop chemically activated carbon that is capable of removing contaminants from water. This study aims to evaluate the preliminary use of olive pit (OP) derived activated carbon for water treatment from Methylene Blue MB. The effectiveness of olive pits as a pollutant's adsorbent was investigated under various activation conditions (i.e., particle size, pH, temperature, natural water, distilled water) and using two activating agents: H3PO4 and H2SO4. In total, two samples were investigated; the adsorption process attained equilibrium between 60 min and 120 min, while the results indicated the best performance achieved (i.e., highest absorption) at a size of 0.6 mm, a temperature of 30 °C, and a base medium (i.e., a pH equal to 8.06). Furthermore, it was found that the natural matter present in natural spring water is responsible for competitive adsorption effects; thus, distilled water had better results. This sample was prepared with olive pits prepared with H3PO4. [ABSTRACT FROM AUTHOR]

Environmental problems caused by human intervention in nature are some of the most critical challenges facing human societies. It is essential to use suitable adsorbents to remove pollutants. The abundance, natural abundance and low cost of fine soil have made it a good candidate for removing environmental pollutants. In this research, removal of safranin dye by natural and acidic-organic-treated fine soil with sulfuric acid and ethanolamine was studied. The characteristics of natural and acidic-organic-treated fine soil were confirmed using X-ray diffraction, Fourier-transform infrared spectroscopy, Brunauer–Emmett–Teller and scanning electron microscopy techniques. The adsorbents were placed in contact with different concentrations of safranin dye solution separately. After that, the effects of adsorbent amount (0.4–3.2 g L −1), contact time (0–60 min), adsorbate concentration (5–20 ppm) and pH (3–11) were evaluated regarding the optimum safranin adsorption process. The greatest adsorption capacity of fine soil was calculated as 1250 mg g –1. The experimental results were evaluated using thermodynamic and kinetic models. The data showed that the process follows the Langmuir isotherm model and pseudo-second-order kinetic model. The intraparticle diffusion model estimated the possible mechanism of dye adsorption. Overall, it can be deduced that natural fine soil is an efficient remover of human pollutants. [ABSTRACT FROM AUTHOR]

The country's energy demand is experiencing rapid growth, and fossil fuels remain the primary resources to meet this increasing need. However, global warming poses a significant challenge for governments and industries worldwide. To address this issue, utilizing methane as a fossil fuel and implementing CO2 capture and sequestration can prove to be effective mitigation strategies. This paper presents an innovative idea to utilize unmineable coal seams in the Singrauli coal field for CO2 sequestration while extracting associated CBM to offset the cost of the sequestration process. The findings reveal that the field has great potential for CO2 sequestration. The estimated average maximum sorption capacities of CO2 and CH4 in the coal seams under in situ conditions of the basin are 39.50 m3/t and 11.15 m3/t, respectively. The total maximum sorption capacities of CO2 and CH4 in the potential coal seams are estimated to be 10,758.00 Mm3 and 3,215.00 Mm3, respectively. These results indicate that the unmineable coal seams in the Singrauli coalfield hold potential for CO2 sequestration and the extraction of available CBM from the coal seams. [ABSTRACT FROM AUTHOR]

Porous silica-based adsorbents for hexavalent chromium (Cr(VI)) ion removal were prepared by the combined use of functionalization with (3-glycidyloxypropyl)trimethoxysilane and the grafting of branched and linear polyethyleneimine (BPEI and LPEI). LPEI was prepared from polyethyloxazolin by hydrolysis with HCl. The preparation of LPEI was identified by NMR measurements and the grafting of BPEI and LPEI on the silica beads was confirmed by an XPS analysis. The Cr(VI) ion adsorption of the obtained BPEI-grafted silica beads (BPEI–silica beads) was investigated as a function of the pH value, the content of amino groups, the temperature, the Cr(VI) ion concentration, and the molecular mass of the grafted BPEI chains. The Cr(VI) ion adsorption at pH 3.0 increased with an increase in the content of amino groups, and the maximum adsorption capacity of 1.06 mmol/g was obtained when the content of amino groups was at 2.17 mmol/g. This value corresponds to 589 mg/g−1.8KPEI, and the adsorption ratio of about 0.5 is a noteworthy result. The data fit to the pseudo-second-order kinetic model, and the suitability of this fitting was supported by the results that the adsorption capacity and initial rate of adsorption increased with the temperature. In addition, the equilibrium data followed the Langmuir isotherm model. These results clearly demonstrate that the Cr(VI) adsorption occurred chemically, or through the electrostatic interaction of protonated amino groups on the grafted BPEI chains with hydrochromate ( H C r O 4 − ) ions. A higher adsorption capacity was obtained for the silica beads grafted with shorter BPEI chains, and the adsorption capacity of BPEI–silica beads is a little higher than that of linear PEI-grafted silica beads, suggesting that the Cr(VI) ion adsorption is affected by the chain isomerism of PEI (linear and branched) as well as the molecular mass of the grafted PEI chains, in addition to the content of amino groups. The experimental and analytical results derived from this study emphasize that the BPEI–silica beads can be used as an adsorbent for the removal of Cr(VI) ions from an aqueous medium. [ABSTRACT FROM AUTHOR]

The pursuit of incorporating eco-friendly reinforcing agents in polymer composites has accentuated the exploration of various natural biomass-derived materials. The burgeoning environmental crisis spurred by the discharge of synthetic dyes into wastewater has catalyzed the search for effective and sustainable treatment technologies. Among the various sorbent materials explored, biochar, being renewable, has gained prominence due to its excellent adsorption properties and environmental sustainability. It has also emerged as a focal point for its potential to replace other conventional reinforcing agents, viz., fumed silica, aluminum oxide, treated clays, etc. This study introduces a novel class of polymer nanocomposites comprising of lignin-based biochar particles and poly(ester amide urethane) matrix via a feasible method. The structural evaluation of these nanocomposites was accomplished using Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and powder X-ray diffraction. The polymer nanocomposites exhibited superior mechanical properties with an increment in tensile strength factor by 45% in comparison to its pristine matrix, along with an excellent toughness value of 90.22 MJm−3 at a low loading amount of only 1 wt%. The composites showed excellent improvement in thermal properties with a sharp rise in the glass transition temperature (Tg) value from −28.15°C to 84°C, while also championing sustainability through inherent biodegradability attributes. Beyond their structural prowess, these polymer nanocomposites demonstrated excellent potential as adsorbents, displaying efficient removal of malachite green and tartrazine dyes from aqueous systems with a removal efficiency of 87.25% and 73.98%, respectively. The kinetics study revealed the pseudo second order model to be the precision tool to assess the dye removal study. Complementing this, the Langmuir adsorption isotherm provided a framework to assess the sorption features of the polymer nanocomposites. Overall, these renewable biochar integrated polymer matrices boast remarkable recovery capabilities up to seven cycles of usage with an excellent dye recovery percentage of 95.21% for the last cycle, thereby defining sustainability as well as economic feasibility. [ABSTRACT FROM AUTHOR]

A critical measure of the quality of pharmaceutical proteins is the preservation of native conformations of the active pharmaceutical ingredients. Denaturation of the active proteins in any step before administration into patients could lead to loss of potency and/or aggregation, which is associated with an increased risk of immunogenicity of the products. Interfacial stress enhances protein instability as their adsorption to the air‐liquid and liquid–solid interfaces are implicated in the formation of denatured proteins and aggregates. While excipients in protein formulations have been employed to reduce the risk of aggregation, the roles of albumin as a stabilizer have not been reviewed from practical and theoretical standpoints. The amphiphilic nature of albumin makes it accumulate at the interfaces. In this review, we aim to bridge the knowledge gap between interfacial instability and the influence of albumin as a surface‐active excipient in the context of reducing the immunogenicity risk of protein formulations. [ABSTRACT FROM AUTHOR]

Abstract Andesite was employed to effectively extract mercury(II) in an aqueous solution. After evaluating its characteristics, andesite was characterized by applying modern techniques such as BET and TGA methods. The study employed SEM and TEM measurements to analyze the variation in the surface shape and crystallinity of the metal due to adsorption. Using the EDX process, the chemical composition, weight, and atomic percentage of each element of andesite were determined. FTIR techniques were also used to confirm the TEM–EDX findings. Zeta potential was estimated. Cycles of regeneration and desorption have been examined. 99.03% was the highest uptake percentage. Adsorbent quantity (0.0025–0.05) g/L, contact time (5–60) min, pH (2–10), temperature (25–60) °C, and dose (0.0027, 0.0044, 0.0125, 0.0155, and 0.0399) mg/L all affect the amount of removal that increases with the increase in contact time, pH, dose, and temperature but drops as the metal ion concentration rises. The ideal values for contact time, pH, metal ion concentration, dose, and temperature were found to be, respectively, 30 min, 0.0155 mg/l, 0.02 g/l, and 40 °C. The calculation of thermodynamic parameters, including ΔH, ΔG, and ΔS, was imperative in establishing that the mechanism of heavy metal adsorption on andesite was endothermic, exhibiting a physical nature that escalated with temperature rise. The Freundlich adsorption equation's linear form is matched by the adsorption of mercury(II) on andesite; constant n was 1.85, 1.06, 1.1, and 1.1, whereas the Langmuir constant qm was found to be 1.85, 2.41, 3.54, and 2.28 mg/g at 25–60 °C. Furthermore, adsorption follows a pseudo-second-order rate constant of (3.08, 3.24, 3.24, and 13) g/mg/min under identical temperature conditions, as opposed to a first-order rate constant of 4, 3, 2.6, and 2. Hg2+, NH4 +, Cl−, Br−, NO3 −, SO4 2−, Na+, K+, H2S, and CH3SH were all extracted from wastewater by this application.

In this study, a discontinuous Galerkin (DG) finite element method is employed to solve the nonlinear equilibrium dispersive (ED) model, for the simulation of multi-component gradient elution chromatography using a liquid mobile phase in fixed-bed columns. The ED model comprises a set of coupled nonlinear convection-dominated partial differential equations integrated with nonlinear Langmuir type adsorption isotherms. Gradient elution, characterized by the gradual increase in eluent strength through variations in the chemical composition of the mobile phase, is analyzed. An investigation into the advantages of gradient elution chromatography in comparison to isocratic elution is conducted via a sequence of numerical test experiments that assess the influence of solvent strength, modulator concentration, gradient start and end times, and gradient slope on the elution profiles and temporal moments. It has been observed that gradient elution chromatography influences the behavior, shape, and propagation speed of elution profiles, which subsequently affect the cycle time and column efficiency. The results of this study provide significant insights that are critical for understanding, optimizing, and enhancing gradient elution chromatography. [ABSTRACT FROM AUTHOR]

Herein, we report the removal of methylene blue (MB) dye from water by Cu(II)-quinoxaline, 3,3-thiodipropionate mixed ligand coordination polymer synthesized as [Cu2(TDPH)4(QNX)]·DMF. Characterization of the synthesized material was carried out by elemental analysis, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), BET surface area analysis, X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and UV–visible spectroscopy. ν(C = O) and ν(C–O) absorption bands were detected at 1735 and 1093 cm−1, respectively, while ν(C = N) was observed at 1608 cm−1 in the synthesized compound. The synthesized material was used as adsorbent for the removal of MB dye from aqueous solution using batch adsorption technique. The maximum adsorption capacity was found to be 7.9745 mg/g, while the maximum decolorization efficiency for the adsorbent was observed to be 99.04%. Adsorption data from the study fitted the Langmuir isotherm with an R2 value of 0.9815, while the adsorption kinetics followed the pseudo-second-order kinetic model with an R2 value of 0.9953. The results obtained from the study, therefore showed that the synthesized materials could be used as adsorbents in wastewater treatment. [ABSTRACT FROM AUTHOR]

The present research aimed to investigate the impact of some synthetic derivatives of pyridone (6-amino-1-(4-hydroxyphenyl)-4-(4-methoxyphenyl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitrile (PYR-2) and 6-amino-1-(4-hydroxyphenyl)-2-oxo-4-phenyl-1,2-dihydropyridine-3,5-dicarbonitrile (PYR-3))on copper corrosion inhibition behavior in HCl acid solution using electrochemical methods, including potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS). Using FTIR, 1HNMR, and mass spectroscopy methods, the two compounds ((PYR-2) and (PYR-3)) were confirmed and characterized. With the two compounds added to corrosive media, the double-layer capacitance value decreases. In the case of 18 × 10−5 M, they reached maximum efficiency of 91.9% and 90.3%, respectively. Having studied its behavior during adsorption on copper, it was concluded that it follows chemical adsorption and Langmuir isotherm and may be considered mixed-type inhibitors. [ABSTRACT FROM AUTHOR]

In this research, a novel nano-biocomposite material, namely, tungsten trioxide-Butea monosperma leaf powder (WO3@BLP), is an effective and eco-friendly adsorbent used for the mitigation of congo red (CR) and crystal violet (CV) dyes from its aqueous phase. The as-prepared WO3@BLP was characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), DLS analysis, and TGA. Many factors such as solution pH, WO3@BLP dose, temperature, contact time, and initial CR/CV dye concentrations were exploited to monitor the adsorption efficiency of WO3@BLP composites. The biosorption of both CR and CV dyes followed the Langmuir isotherm, with maximum adsorption capacities (qmax) reaching 84.91 mg g−1 for CR at pH 2.3 and 162.75 mg g−1 for CV at pH 8, fitting of kinetics data to the PSO model with closed values of qeexp (mg g−1) and qecal (mg g−1), i.e., 25.69 to 25.38 mg g−1 for CR dye and 29.06 to 29.08 mg g−1 for CV dye. The interaction mechanism behind the adsorption of CR and CV dyes onto the WO3@BLP bionanocomposite includes electrostatic interaction and surface complexation. The synthesized materials were tested for antifungal activity against three different Candida cells, i.e., C. albicans ATCC 90028, C. glabrata ATCC 90030, and C. tropicalis ATCC 750, by using broth dilution method on the minimum inhibiting concentration (MIC). Furthermore, the cytotoxicity of nano-formulated WO3@BLP was studied by in vitro hemolytic assay on a human host. Overall, this research presents a pioneering nano-biocomposite, WO3@BLP, as a sustainable adsorbent for CR and CV dye removal, adhering to Langmuir isotherm and pseudo-second-order kinetics. Its multifaceted approach includes elucidating interaction mechanisms, demonstrating antifungal activity, and assessing cytotoxicity, marking a significant advancement in environmental remediation. [ABSTRACT FROM AUTHOR]

Andesite was employed to effectively extract mercury(II) in an aqueous solution. After evaluating its characteristics, andesite was characterized by applying modern techniques such as BET and TGA methods. The study employed SEM and TEM measurements to analyze the variation in the surface shape and crystallinity of the metal due to adsorption. Using the EDX process, the chemical composition, weight, and atomic percentage of each element of andesite were determined. FTIR techniques were also used to confirm the TEM–EDX findings. Zeta potential was estimated. Cycles of regeneration and desorption have been examined. 99.03% was the highest uptake percentage. Adsorbent quantity (0.0025–0.05) g/L, contact time (5–60) min, pH (2–10), temperature (25–60) °C, and dose (0.0027, 0.0044, 0.0125, 0.0155, and 0.0399) mg/L all affect the amount of removal that increases with the increase in contact time, pH, dose, and temperature but drops as the metal ion concentration rises. The ideal values for contact time, pH, metal ion concentration, dose, and temperature were found to be, respectively, 30 min, 0.0155 mg/l, 0.02 g/l, and 40 °C. The calculation of thermodynamic parameters, including ΔH, ΔG, and ΔS, was imperative in establishing that the mechanism of heavy metal adsorption on andesite was endothermic, exhibiting a physical nature that escalated with temperature rise. The Freundlich adsorption equation's linear form is matched by the adsorption of mercury(II) on andesite; constant n was 1.85, 1.06, 1.1, and 1.1, whereas the Langmuir constant qm was found to be 1.85, 2.41, 3.54, and 2.28 mg/g at 25–60 °C. Furthermore, adsorption follows a pseudo-second-order rate constant of (3.08, 3.24, 3.24, and 13) g/mg/min under identical temperature conditions, as opposed to a first-order rate constant of 4, 3, 2.6, and 2. Hg2+, NH4+, Cl−, Br−, NO3−, SO42−, Na+, K+, H2S, and CH3SH were all extracted from wastewater by this application. [ABSTRACT FROM AUTHOR]

The corrosion inhibition performance of L(-)- Cystine on copper alloy immersed in 2 M HNO3 solution is investigated using weight loss, potentiodynamic polarisation, electrochemical impedance spectroscopy, and scanning electron microscopy. Potentiodynamic polarization measurements confirmed that L(-)-Cystine behaved as mixed-type inhibitor. The highest corrosion inhibition efficiency was 98.99% at 298 K and decreased with increasing temperature. The Nyquist plots displayed an increase in the capacitive loops with increasing the concentration of the inhibitor. The mechanism of inhibition obeys Langmuir isotherm. SEM images confirm the adsorption of L(-)-Cystine on the surface of the cooper alloy [ABSTRACT FROM AUTHOR]

Copyright of Chemical Engineering (China) / Huaxue Gongcheng is the property of Hualu Engineering Science & Technology Co Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study utilized zinc-tin nanoflowers (ZT-NFs) in a batch adsorption treatment process to effectively remove cadmium from synthetic wastewater. The batch adsorption strategy was optimized using the univariate approach to enhance the efficiency of the adsorption process. The dominant parameters examined in the optimization experiments were pH/volume of buffer solution, nanoflower amount, and sample agitation type/period. After determining the optimal batch adsorption conditions, equilibrium studies were performed by adding cadmium to synthetic wastewater at concentrations in the range of 1.0 – 40 mg/L. The quantification accuracy for cadmium was improved by developing the calibration plot with spiked sample matrix. The equilibrium data were subjected to mathematical modelling utilizing the Langmuir adsorption isotherm model. The calculated isotherm constants indicated a well-fitted isotherm model to the experimental data. The reported ZT-NFs-based adsorptive removal strategy was effectively employed to remove cadmium from synthetic wastewater. [ABSTRACT FROM AUTHOR]

The Langmuir isotherm, originally developed to study the adsorption of gases, has been modified in this research to investigate the adsorption of solutes in the solution phase. The modification considers the adsorption of solvent molecules and the interactions between adsorbed particles and the species in the solution. Three equations have been obtained to calculate the contribution of these additional effects on the Gibbs free energy, enthalpy, and entropy of solute adsorption based on the new isotherm. The study evaluated the efficiency of the new isotherm in the adsorption of some metal ions in an aqueous solution and found that it is more accurate than the Langmuir isotherm and provides a deeper insight into the adsorption process in the solution phase. Practitioner Points: Modification of the Langmuir isotherm for adsorption in solution.Comparison of the efficiency of the Langmuir and modified Langmuir isotherms.Accurate determination of ∆Hadso$$ \Delta {H}_{ads}^o $$ and ∆Sadso$$ \Delta {S}_{ads}^o $$ for Pb(II), Cd(II), and Ni(II) adsorption. [ABSTRACT FROM AUTHOR]

The stem extract of Solanum Lycopersicum prepared using the methanol extraction method has been investigated as an environment-friendly inhibitor for low-carbon steel in monoprotic(1N HCl) and diprotic(1N H2SO4) solvents and characterized with FT-IR. A maximal inhibition efficiency of 81.8% in 1 N Hydrochloric acid and 92.92% in 1 N Sulfuric acid is assessed under a certain set of conditions of inhibitor concentration and temperature using weight loss, electrochemical impedance spectroscopy and potentiodynamic polarization. The results present Solanum Lycopersicum extract as a mixed-type inhibitor that predominantly influences the cathodic reaction and followed the Langmuir adsorption isotherm. Reduction in the value of average roughness (Ra)of the surface from 217 nm to 55 nm (in 1 N HCl) and 139.6 nm to 28 nm (in 1 N H2SO4) was observed with AFM after the application of the inhibitor which confirms the formation of a protective membrane and provides green inhibition on the low-carbon steel/solution interface. [ABSTRACT FROM AUTHOR]

Phosphate sorption on rendzina soil was studied by P-32 heterogeneous isotopic exchange under a steady-state. There are two types of sorbed phosphate, namely strongly and weakly bonded phosphate, the latter being able to exchange with phosphate (H232PO4−) ions in the soil solution. The experimental kinetic data was not fitted by the one exponential kinetic model. Starting from this observation, a new kinetic model is established by assuming two types of weakly bonded phosphate, which take part in the two parallel exchange processes. A biexponential kinetic equation is obtained, which fits the experimental data much better than the one exponential equation. [ABSTRACT FROM AUTHOR]

In this article, FeNi3@MnO2 core–shell nanostructure has been used for the first time to remove Pb(II) and Cd(II) from aqueous solutions by adsorption. The MnO2-coated FeNi3 magnetic nanoparticles were synthesized by the hydrothermal method and characterized by various analytic methods such as X-ray diffraction, Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscope, transmission electron microscope, and atomic absorption spectrometry. Adsorption parameters such as pH, contact time, adsorbent amount, and initial concentration of metal ions were investigated and optimized. FTIR Spectrum of the nanostructure was used to analyze the adsorption mechanism. FeNi3@MnO2 adsorbent was shown to follow the Langmuir adsorption isotherm and the pseudo-second-order kinetic model. The thermodynamics of adsorption confirmed an endothermic and spontaneous process. The calculated maximum adsorption capacities of the adsorbent for Pb(II) and Cd(II) were 129.2 mg g−1 and 127.8 mg g−1 at room temperature, which confirmed a good adsorption performance, especially for Cd(II). The adsorbent had a good removal efficiency of more than 99% for both metal ions, which was achieved in only 20 minutes. [ABSTRACT FROM AUTHOR]

This work focuses on the characterization of five palygorskite clays from the Brazilian state of Piaui and their feasibility as eco-friendly adsorbents for the removal of Fe3+ ions from aqueous solutions. For characterization, we applied the techniques of X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), size distribution measurements, density measurement by He pycnometry, superconducting quantum interference device (SQUID) magnetometry, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTA), zeta potential measurement, hydrophobicity determination by contact angle, Brunauer–Emmett–Teller surface area analysis (BET technique) and atomic force microscopy (AFM). Batch experiments were performed in function of process parameters such as contact time and initial concentration of Fe3+. The natural palygorskites (Palys) had excellent performance for the removal of Fe3+ from aqueous solutions by adsorption (around 60 mg/g), and the Langmuir is supposedly the best model fitted the experimental data. [ABSTRACT FROM AUTHOR]

Wastewater discharges from industrial processes typically include elevated concentrations of contaminants, which largely consist of potentially harmful chemicals such as heavy metals. These contaminants are characterized by their slow rate of decomposition. Hence, the removal of these metallic ions from effluents poses a challenge. Among different treatments, the adsorption approach has considerable potential due to its ability to effectively eliminate both soluble and insoluble pollutants from effluent, even at lower levels of concentration. Of various wastes, fly ash (FA) material has been the subject of attention because it is abundant, has favorable qualities, and contains a high percentage of minerals. This review investigates multiple facets, with a specific focus on the application of FA, an industrial byproduct, as an adsorbent in removing heavy metals. A comprehensive examination was conducted on a range of concerns pertaining to the pollution caused by metallic ions, including the underlying causes, levels of contamination, health implications of heavy metals, and removal methods. Multiple factors were found to affect the adsorption process. Of all the factors, the pH value considerably influences the elimination of heavy metals. An acidic pH range of 2.5–4.5 was found to be optimal for achieving the highest possible elimination of As(V), Cu(II), Hg(II), and Cr(VI). The latter elimination rate reached 89% at the optimal pH level. Most heavy metals' adsorption isotherms conformed to the Langmuir or Freundlich models, while the pseudo-second-order kinetics provided a satisfactory match for their removal. Using a raw FA, adsorption capacities were achieved in the removal of metallic ions, Ni(II), Pb(II), and Cr(VI), that ranged from 14.0 to 23.9 mg g−1. Meanwhile, the FA-zeolite showed a remarkable capacity to adsorb ions Mn(II), Ni(II), Cd(II), Cu(II), and Pb(II), with values ranging from about 31 to 66 mg g−1. The cost analysis showed that the treatment of FA is economically advantageous and may result in significant cost reductions in comparison to commercial adsorbents. In summary, FA is an inexpensive waste material with potential for water treatment applications and several other purposes due to its excellent chemical and mineralogical composition. [ABSTRACT FROM AUTHOR]

This work focuses on the characterization of five palygorskite clays from the Brazilian state of Piaui and their feasibility as eco-friendly adsorbents for the removal of Fe3+ ions from aqueous solutions. For characterization, we applied the techniques of X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), size distribution measurements, density measurement by He pycnometry, superconducting quantum interference device (SQUID) magnetometry, Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTA), zeta potential measurement, hydrophobicity determination by contact angle, Brunauer–Emmett–Teller surface area analysis (BET technique) and atomic force microscopy (AFM). Batch experiments were performed in function of process parameters such as contact time and initial concentration of Fe3+. The natural palygorskites (Palys) had excellent performance for the removal of Fe3+ from aqueous solutions by adsorption (around 60 mg/g), and the Langmuir is supposedly the best model fitted the experimental data.

In this study, we aimed to develop a mathematical description of the process of phosphate sorption on Rockfos® material using the Langmuir isotherm and determine the basic parameters for modeling this process. The Rockfos® material was formed through the thermal treatment of opoka at 980 °C and is highly reactive due to its significant calcium and silicon compound content. This study included an evaluation of the phosphate retention efficiency on the material as a function of the phosphate concentration in the initial solution (0.5 mg/L, 1.0 mg/L, and 2.0 mg/L), sorbent grain size (1.0–1.6 mm, 1.6–2.5 mm, and 2.0–5.0 mm), and process temperature (5 °C, 10 °C, 15 °C, 20 °C, and 25 °C). It was found that an increase in the process temperature and the phosphate concentration in the solution favored sorption, while the effect of the sorbent grain size was ambiguous. It was determined that sorption can be described well using the Langmuir linearization of the Langmuir model. Thermodynamic analysis and the separation coefficient suggest that phosphorus sorption on Rockfos® material is primarily based on chemisorption, and the process is endothermic and spontaneous over the entire temperature range. The determined parameters of the tested material, especially the qmax (maximum sorption capacity), provide a basis for the design of a filter for removing phosphate from wastewater, assuming that the load is equal to the inflow to the filter and adheres to the specified requirements for treated wastewater.

The inhibitory effect of A. orientalis L. extract (AO) on aluminum corrosion in a 1.0 M HCl solution was investigated utilizing weight loss, electrochemical polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The results show that AO is a potent inhibitor in an acidic environment, and that the inhibition potency increases with concentration. Temperature investigations showed that, in an acidic medium, the efficiency decreased, increased, and then decreased as the temperature rose. Adsorption isotherms from Freundlich, Temkin, El Awady, and Redlich–Peterson (R-P) approximated the inhibitor’s adsorption properties. For the inhibitory behavior, a physical and chemical adsorption mechanism is proposed. The adsorption process’s thermodynamic parameters (Ea, ΔH*, and ΔS*) were determined and explained. The inhibitor, AO, was identified as a mixed-type (anodic and cathodic) inhibitor based on polarization studies. According to the SEM findings, the inhibitor partially covers the metal surface, providing it with a respectable level of protection. The weight loss, electrochemical polarization, EIS, scanning electron microscopy (SEM), and quantum chemical calculations show a strong agreement, indicating that the AO extract is a highly effective inhibitor of aluminum in an acidic solution.