Langmuir Isotherm Research Articles

Thiol-Functionalized Cobalt Ferrite (CoFe2O4@MPTS) Nanoparticles as Cutting-Edge Adsorbents for Bovine Serum Albumin.

This paper describes the synthesis of CoFe₂O₄ nanoparticles via a simple ultrasonic-assisted co-precipitation method and their functionalization with thiol groups using (3-Mercaptopropyl)trimethoxysilane (MPTS) as the functionalizing agent. The use of ultrasonic energy not only serves as a green energy source but also reduces the reaction time fivefold compared to conventional methods. The synthesized CoFe₂O₄ nanoparticles were characterized for their surface and internal properties using instrumental techniques such as Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Vibrating Sample Magnetometer (VSM). The functionalized nanoparticles were applied for the effective adsorption of bovine serum albumin (BSA) from a buffered aqueous medium. To enhance the adsorption performance, the influence of pH, amount of solid adsorbent, initial BSA concentration, shaking time, and temperature on protein adsorption was investigated. Lagergren pseudo-second-order adsorption kinetics fitted the BSA adsorption data well, with an acceptable R² value of 0.976. Additionally, the BSA adsorption data were analyzed using Langmuir and Freundlich isotherm models, and it was concluded that the experimental data followed the Langmuir equation more closely than the Freundlich equation. At an initial pH of 5.57 (acetate buffer), the adsorption capacity (Q₀) for BSA protein was found to be 200mg/g. The thermodynamic study revealed ΔS° and ΔH° values of 17.40J/mol·K and - 45.37kJ/mol, respectively.

Employment of Fe3O4/Fe2TiO5/TiO2 Composite Made Using Ilmenite for Elimination of Methylene Blue

A novel material was created from natural ilmenite sand, and methylene blue (MB) was used to test the material’s capacity to remove colors from wastewater. The material was synthesized by neutralizing the acid leachate obtained by Ilmenite sand digestion, followed by drying at 180 °C. It was characterized by XRD, Raman, TEM, SEM, XPS, XRF, and BET techniques. The crystal nature of the composite is Fe3O4/Fe2TiO5/TiO2. The surface area, average pore size and total pore volume of the composite are 292.18 m2/g, 1.53 nm, and 0.202 cc/g, respectively. At pH 10, 10 mg/L MB, and 10 mg of the material resulted in a maximum adsorption capacity of 24.573 mg/g. Using 5 mg/L increments, the dye concentration was adjusted between 10 and 25 mg/L, yielding equilibrium adsorption capacities of 24.573, 31.012, 41.443, and 52.259 mg/g with 10, 15, 20, and 25 mg/L, respectively. The greatest adsorbent capacity of 24.573 mg/g was achieved with 10 mg of the adsorbent and 10 mg/L MB. The adsorbent dosage ranged from 10, 25, 45, 65, and 100 mg. MB was adsorbed via pseudo-second-order kinetics with an adsorption capacity of 24.863 mg/g. The intraparticle diffusion model showed that MB adsorption occurs in three stages, with intra-particle diffusion constants of 1.50, 2.71, 3.38, and 4.41 g/mg min1/2. Adsorption followed the Langmuir isotherm model. The obtained thermodynamic parameters ΔG, ΔH, and ΔS were −27.5521 kJ/mol at 298 K, 2.571 kJ/mol, and 0.101 kJ/mol, respectively. Regeneration studies of the adsorbent were carried out for five cycles, indicating some activity loss after each cycle.

Effect of pyrolytic temperature on the adsorption of Pb(II) from synthetic wastewater onto bamboo chopstick biochar: a conventional vs. microwave-assisted pyrolysis approach

This study investigated the effects of different pyrolytic temperatures on Pb(II) adsorption from synthetic wastewater using waste bamboo chopsticks (BCs) produced via conventional and microwave-assisted pyrolysis. Eleven biochars were prepared and characterized using Brunauer‒Emmett‒Teller analysis, elemental analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy. Thereafter, the selected biochars were further analyzed through batch adsorption studies. The influence of adsorbent dose, initial Pb(II) concentration, and contact time on the removal of Pb(II) from synthetic wastewater was studied. For the adsorbent dose, good removal efficiencies and adsorption capacities were observed at an adsorbent dose of 2 g L−1 and at an initial concentration of 50 mg L−1. For the initial Pb(II) concentration, high adsorption capacities and removal efficiencies were observed at 50 mg L−1 for concentrations ranging from 5 to 100 mg L−1. The contact time reached equilibrium within 24 h, where BC 450 W had the highest removal efficiency of 99.9%. Furthermore, the Langmuir isotherm model best represented the adsorption of Pb(II) onto biochar, with the highest qm of 81 mg g−1 at R2 = 0.978. Pseudo-second-order kinetics provided the best overall fit for the adsorption kinetics of the biochars, with R2 = 1.00 for BC 450 W and BC 700 °C. Among the many chemisorption processes identified in previous studies, surface complexation has been identified as a possible adsorption mechanism for Pb(II) on the biochars produced. BC biochar could be a sustainable means for remediating polluted mine water and managing waste.

Synthesis and adsorption performance of Cu-BTC microspheres for Methylene Blue Dye

The MOFs, copper–1,3,5- benzenetricarboxylate (Cu-BTC) samples were synthesized by immersing self-assembled films in solutions of copper nitrate and trimesic acid through a biomimetic mineralization method. During the synthesis, self-assembled monolayers with different end groups acted as templates, facilitating the nucleation and growth of Cu-BTC crystals. The resulting products were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) analysis. The influence of the synthesized materials on the adsorption performance of methylene blue (MB) dye was systematically investigated. The results show that the Cu-BTC compound microspheres, induced by sulfonic acid groups, have a uniform morphology and exhibit effective adsorption of MB dye. The theoretical maximum adsorption capacity of these microspheres for MB dye is 75.6 mg·g–1. The adsorption data from this process are consistent with both the pseudo-first-order kinetic model and the Langmuir isotherm model. After four adsorption-regeneration cycles, the microspheres retained a high adsorption efficiency for MB dye.

Adsorption of fluorine from lepidolite hydrometallurgy wastewater by aluminum modified zeolite.

Fluoride contamination is a serious environmental problem in lepidolite hydrometallurgy wastewater. The treatment of fluoride-bearing wastewater is challenging because of the presence of coexisting ions including lithium (Li+), rubidium (Rb+), silicate (SiO32-), sulfate radical (SO42-). However, aluminum-modified zeolite (Al@zeolite) with sufficient hydroxyl groups and high adaptability has unique advantages for eliminating fluoride from lepidolite hydrometallurgy wastewater. Al@zeolite was prepared on natural zeolite by an atmospheric process and then used for the adsorption of fluorine from fluoride-bearing wastewater produced by the lepidolite hydrometallurgy process. The results of material characterization confirmed the successful immobilization of aluminum within the zeolite pores and indicated the formation of zeolite-Al-OH. The zeolite host significantly enhanced the chemical stability of Al@zeolite against pH changes for a wide pH range of 2.0-10.0. The adsorbent had a surface area of 33.46m2/g and demonstrated excellent capacity and selectivity for fluoride adsorption. Notably, a maximum adsorption of 98.6% was observed at a pH value of 6.0 for a duration of 20min with a fluoride content of 20mg/L, and the equilibrium concentration decreased to 0.4mg/L. The results of fluorine adsorption showed that fluoride uptake onto Al@zeolite agreed well with the pseudo-second-order kinetic model and the Langmuir isotherm model. The reusability of the substance was evaluated for up to eight cycles following consecutive regeneration with 0.2mol/L AlCl3. The exhausted Al@zeolite was effectively regenerated through simple alkaline treatment for recycling. The above results verified that Al@zeolite is a new kind of efficient defluoridation adsorbent for lepidolite hydrometallurgy wastewater with practical application prospects.

Hydrochar Production from Cigarette Butts and Tobacco for Dye Adsorption

In this study, tobacco waste generated from cigarette and cigar production, as well as discarded cigarette butts resulting from cigarette use, were recycled and their use as adsorbent materials was investigated. For this purpose, both products underwent various thermal and chemical treatments and were converted into hydrochar form. Chemically activated hydrochar was used in dye removal experiments due to its high surface area and adsorbent properties. Malachite green was selected as the dye material for the project. Adsorption experiments were conducted at different initial concentrations, adsorbent doses, and contact times. In experiments on the removal of malachite green with butts and tobacco waste hydrochars, removal rates as high as 99% were obtained. As a result of adsorption experiments carried out with both hydrochars, it was observed that the adsorption fits the Langmuir isotherm model and the Pseudo-Second-Order kinetic model. Tobacco waste and discarded cigarette butts, which are cheap, readily available, and abundant, were found to be effective alternative adsorbents for malachite green removal.

Boosting the Sustained Release Performance of Metronidazole and Ornidazole with MIL-53(Fe) Derived Spherical Porous Carbon.

Metal-organic framework (MOF) derived spherical porous carbon (SPC) has potential application value in the field of adsorption and sustained release of nitroimidazole drugs. This work used MIL-53(Fe) as a precursor and prepared spherical 3-aminophenol-formaldehyde resin containing MIL-53(Fe) crystals using the advanced Stöber method, followed by the successful preparation of MIL-53(Fe) derived SPC (MSPC) with a structure containing both micropores and mesopores through high-temperature carbonization. The effects of the doping amount of MIL-53(Fe) on the sphericity and particle size of MSPC were investigated. The drug uptake capacity and sustained release performances of MSPC for metronidazole (MNZ) and ornidazole (ONZ) were assessed through batch tests, along with an investigation into the impact of varying pH levels on the sustained release performances. The experimental findings revealed that the drug loading of MNZ and ONZ onto MSPC achieved 111 and 120 mg/g, respectively, with a sustained release time of up to 24 h. The drug loading process adhered to the Langmuir isotherm adsorption model and conformed to the pseudo-second-order kinetics model, whereas the sustained release mechanism was consistent with the Korsmeyer-Peppas model. Furthermore, cytotoxicity and cyclic drug loading experiments indicated that MSPC exhibited good biocompatibility and stability. Therefore, this study provides new ideas for the development of SPC drug carriers.

Enhanced Lead and Zinc Removal via Prosopis Cineraria Leaves Powder: A Study on Isotherms and RSM Optimization

This study investigates the potential of Prosopis cineraria Leaves Powder (PCLP) as a biosorbent for removing lead (Pb) and zinc (Zn) from aqueous solutions, optimizing the process using Response Surface Methodology (RSM). Prosopis cineraria, commonly known as Khejri, is a drought-resistant tree with significant promise in environmental applications. The research employed a Central Composite Design (CCD) to examine the independent and combined effects of key process variables, including initial metal ion concentration, contact time, pH, and PCLP dosage. RSM was used to develop mathematical models that explain the relationship between these factors and the efficiency of metal removal, allowing the determination of optimal operating conditions. The experimental results indicated that the Langmuir isotherm model was the most appropriate for describing the biosorption of both metals, suggesting favorable adsorption characteristics. Additionally, the D-R isotherm confirmed that chemisorption was the primary mechanism involved in the biosorption process. For lead removal, the optimal conditions were found to be 312.23 K temperature, pH 4.72, 58.5 mg L−1 initial concentration, and 0.27 g biosorbent dosage, achieving an 83.77% removal efficiency. For zinc, the optimal conditions were 312.4 K, pH 5.86, 53.07 mg L−1 initial concentration, and the same biosorbent dosage, resulting in a 75.86% removal efficiency. These findings highlight PCLP’s potential as an effective, eco-friendly biosorbent for sustainable heavy metal removal in water treatment.

Adsorption of Vanadium (V) on Amorphous and Modified Silica

In this work, we investigate V(V) sorption on amorphous and modified silica. Silicon dioxide was obtained from the metallurgical slag. The impact of modification on vanadium sorption was studied. The surface was modified with hydrazides (HDs) and dimethylhydrazides (DMHDs) of the tertiary carbonic Versatic acids CH3R1R2CC(O)OH of the C10–19 fractions. The optimal sorption conditions on the unmodified sorbent were pH 4, 1 h, and 40 °C. The sorption capacity of V(V) ions increased with surface modification. For modified sorbents, the range of action shifted to a more acidic area (2.0–3.0), where the HV10O285− polyanion formed a complex with N′,N′-dimethylhydrazide groups. When studying the kinetics of the V(V) sorption process on silica samples, the optimum time of adsorption equilibrium establishment (10 min) and reaction mechanism were determined. The sorption process was significantly accelerated by surface modification. The vanadium sorption process is described by pseudo-second-order kinetics. The study of adsorption isotherms revealed that the vanadium sorption isotherm corresponds to the Langmuir equation. The differences in the extraction of vanadium ions are explained by different sorption mechanisms, which are associated with the variety of vanadium forms in the solution.

An eco-friendly corrosion inhibitor for steel used in desalination systems during acid cleaning: Irish ivy extract.

Examining Irish ivy extract's (IIE) potential as a novel corrosion inhibitor to preserve C-steel in 2.0M H2SO4 solution under dynamic conditions is the main goal of this work. Investigations on weight loss, surface morphology, thermodynamics, electrochemistry (polarization and impedance), and adsorption isotherms all contributed to the achievement of this goal. The results demonstrated that the IIE extract's inhibitory effectiveness increases with concentration, reaching a maximum of 94.2% at 0.5g L-1. The approach that most nearly matched the experiment's results was the Langmuir adsorption isotherm. The activation energy rises to 61.4kJ mol-1 when IIE extract is added, compared to 46.9kJ mol-1 (2.0M H2SO4). The mixed type behavior of the IIE extract was confirmed by electrochemical method. The IIE extract effectively adsorbed on the C-steel, as confirmed by the FT-IR and SEM examinations. Many compounds, including α-hederin, hederacoside C, hederacoside D, and chlorogenic acid, which may operate as the main agents of corrosion control, were found by HPLC analysis of the IIE extract.

Self-Assembled Bolaamphiphile-Based Organic Nanotubes as Efficient Cu(II) Ion Adsorbents.

Self-assembled organic nanotubes (ONTs) have been actively examined for various applications such as chemical separations and catalysis owing to their well-defined tubular nanostructures with distinct chemical environments at the wall and internal/external surfaces. Adsorption of heavy metal ions onto ONTs plays an essential role in many of these applications but has rarely been assessed quantitatively. Herein, we investigated interactions between Cu2+ and single-/quadruple-wall bolaamphiphile-based ONTs having inner carboxyl groups with different inner diameters, COOH-ONT10nm and COOH-ONT20nm. We first examined the effects of Cu2+ on their nanotubular structures using SAXS, STEM, and AFM. COOH-ONT10nm was stable in aqueous Cu2+ solution in contrast to COOH-ONT20nm owing to the presence of polyglycine-II-type hydrogen bonding networks within its wall. Subsequently, we studied the Cu2+ adsorption behavior of COOH-ONT10nm by monitoring the concentration of unbound Cu2+ using linear sweep anodic stripping voltammetry. The Cu2+ adsorption was quick, attributable to efficient Cu2+ partitioning through the open ends of the ONT, followed by fast Cu2+ diffusion in the uniform, relatively large nanochannel. More importantly, the Cu2+ adsorption capacity and affinity of COOH-ONT10nm were measured under different pH conditions using the Langmuir adsorption model. The adsorption capacity was similar at the pH range examined, showing the participation of approximately 25% of the inner carboxyl groups in the adsorption. The adsorption affinity increased with pH, indicating the essential role of the deprotonated carboxyl groups in Cu2+ adsorption. Most interestingly, the Langmuir adsorption constant was significantly higher than those of previously reported synthetic adsorbents and planar monolayer based on carboxyl binding sites. The high Cu2+ affinity of the ONT was attributable to the highly dense binding sites on the well-defined nanoscale concave structure of the inner channel. These results provide a valuable guideline for designing self-assembled nanomaterials for efficient chemical separations, detection, and catalysis.

Simple Use of Low-cost and Available Adsorbent for Cationic Dye Adsorption from Aqueous Solution

The aim of this work was to study the adsorption of methylene blue (MB) on local agricultural waste in the batch process. The adsorbent, washed rice husk (WRH) was subjected to some physical and chemical analyses such as EDX/SEM, FT-IR, XRD and XRF. The adsorbent showed an amorphous structure and dominated by silica in its composition. The influence of adsorption parameters such as contact time, adsorbent dose and initial concentration was studied. The mass of washed rice husk (WRH) varied at 1 to 6 g, the initial concentrations MB (50-250 mg/L) and the contact time (10-90 min). The MB removal percentage reached 86% with a WRH amount of 4.5 g and an optimal time of 30 min. Langmuir and Freundlich isotherm models were used to process the adsorption data. Q<sub>max</sub>, the maximum adsorption capacity of MB from Langmuir’ model was 13.23 mg.g<sup>-1</sup>. The values of the R<SUB>L</SUB> constant varying between 0-1 for the initial concentrations studied proved that the adsorption is favorable. The value of the parameter n being less than 1obeys the condition of heterogeneity. Pseudo-first order and pseudo-second order models were used to study the kinetic adsorption process. The kinetic parameters calculated from each model showed that the adsorption of MB on the WRH could be describe by the pseudo-second order.

Electrochemical and Gravimetric Investigation of the Corrosion Inhibition Performance of Clindamycin for Mild Steel in Acidic Media

The corrosion inhibition performance of clindamycin for mild steel in 2.0 M H2SO4 has been studied using gravimetric and electrochemical methods. The results showed that the clindamycin inhibited mild steel corrosion in 2.0 M H2SO4 solution. The inhibition efficiency was found to increase with an increase in the concentration of clindamycin and decrease with an increase in the temperature. The maximum inhibition efficiency was obtained at 303 K (91.1%). Potentiodynamic polarization results reveal that clindamycin is a cathodic-type corrosion inhibitor lower concentrations and an anodic-type corrosion inhibitor at higher concentrations. The experimental data fitted the Langmuir adsorption isotherm and the adsorption of clindamycin was found to be spontaneous. The values of activation energy and Gibb’s free energy were found within the range of limits expected for the mechanism of physical adsorption.

CoFe2O4/graphene oxide/Ostrich Eggshell/chitosan/polypyrrole nanocomposite for removal 4-nitrophenol

A nanocomposite comprising CoFe2O4/Graphene Oxide/Ostrich Eggshell/Chitosan/Polypyrrole (CF/GO/ES/CS/PPY) was fabricated as both an adsorbent and photocatalyst to examine the adsorption and degradation efficiency of the organic pollutant 4-nitrophenol (4-NP), both in the absence of light and under visible light irradiation. The nanocomposite material outperformed adsorption in photocatalytic experiments conducted using the Box-Behnken Design (BBD) within response surface methodology (RSM), which investigated the correlation between responses and process variables and identified optimal combinations with Design Expert software. Under optimal conditions, the highest percentage of adsorption and degradation of 4-NP was achieved, with a pH of 5.04, concentration of 4-NP of 24.73 mg/L, nanocomposite mass of 0.04 g, and time of 27.64 min, resulting in reported efficiencies of 89.76, and 99.98% for adsorption and degradation, respectively. Upon statistical analysis, it is clear that the Langmuir isotherm model is the best fit for the studied phenomena, displaying a strong correlation (0.990) and minimal error. The data suggests that the intraparticle diffusion kinetic model has the highest correlation coefficient (0.9925) among the models examined. The value of ΔG° computed for the adsorption process exhibits an increase from 1.3704 to 3.9439 kJ/mol as the temperature rises, indicating the non-spontaneous nature of the adsorption process.

Application of Magnetic Biochar@Alginate Composite as Adsorbent for Effective Removal of Methylene Blue from Aqueous Media

In recent years, magnetic biochar has been widely used for the removal of dyes in polluted water due to its magnetic separation abilities and has been used as composite adsorbents by incorporating different biomasses into its structure for the removal of such pollutants. In this study, a new composite magnetic biochar@alginate composite (mBC@Alg) was synthesized as an alternative adsorbent for the removal of methylene blue (MB) from aqueous solutions. The primary focus of this intensive preparation procedure is on the synthesis, characterization, and optimization of the mBC@Alg for enhanced MB adsorption capacity. The composite material was characterized using FT-IR analysis and scanning electron microscopy (SEM). Batch adsorption studies experiments were performed to determine the removal efficiencies, pH, adsorbent dose, contact time and initial concentration of MB molecules. Various adsorption isotherms such as Freundlich, Langmuir, Scathard and Dubinin-Radushkevich were used to describe the adsorption behavior at equilibrium. The Langmuir adsorption isotherm was identified as the most appropriate model to explain the observed adsorption phenomena, and the adsorption capacity of mBC@Alg for MB was determined to be 416.67 mg/g using this isotherm. Kinetic studies were carried out using pseudo-first-order and pseudo-second-order kinetic models and it was concluded that the experimental data fit well with the second-order kinetic model. The adsorbent properties of the mBC@Alg composite are particularly effective in removing MB molecules from aqueous solutions.

Synthesis and Evaluation of an Innovative Biochar Nanocomposite Adsorbent Derived from Cycas Revoluta Seeds, with Potential Applications in the Removal of Cationic Dyes

In this study, novel and functional adsorbents were synthesized by using Cycas revoluta seed (CS) biomass. The biomass was subjected to a slow pyrolysis process at a final temperature of 500°C with a heating rate of 10°C/min to synthesize Cycas revoluta seed biochar (CSB). After the thermochemical conversion of biomass into biochar, the nanocomposite structure (ZrO2NP@CSB) was synthesized by adding 5% zirconium oxide (ZrO2) nanoparticles into biochar to increase the adsorption capacity. The synthesized adsorbents (CS, CSB, and ZrO2NP@CSB) were characterized by XRD, FTIR, SEM, and EDX. The adsorption efficiency of these three adsorbents was investigated to remove Malachite Green (MG) and Methylene Blue (MB) dye from an aqueous solution. According to the results obtained from the adsorption experiments of the nanocomposite structure, solution pH had a significant effect on the process and the highest adsorption efficiencies were achieved at pH 9. The optimum adsorbent dose was 0.5 g/L. The process reached an equilibrium after 45 minutes and 90 minutes for MG and MB, respectively. The relevant data were in good agreement with the pseudo-second-order kinetic model. The maximum adsorbent capacities were 129.87 and 117.93 mg/g for MG and MB, respectively. The adsorption mechanism follows a monolayer Langmuir isotherm model. Experiments were carried out at different temperatures (25, 35, 45°C) to determine the effect of temperature on adsorption, and dye removal efficiency slightly increased with temperature. When repeated batch adsorption experiments were compared for raw biomass, biochar, and biochar nanocomposite adsorbents, it was observed that the raw adsorbent had a lower adsorption capacity than the biochar adsorbent. It was found that the biochar nanocomposite had the highest adsorption capacity among these three adsorbents. The findings suggest that ZrO2NP@CSB composite is a promising, cost-effective, and functional material for water treatment and can be employed as an alternative adsorbent for removing dyes.

Evaluation of adsorption characteristic of GG-g-polyacrylic acid P(AA)/CoFe2O4 for the metamorfin hydrochloride (MF) and diclofenac sodium(DCF)

ABSTRACT The removal of contaminants from the water system is so significant for the better human life. Adsorption method is proven to be best method for the decontamination of waste water. Adsorbent based on biohydrogel is widely used for this purpose so biooriginated adsorbent named GG-g- P(AA)/CoFe2O4 (30 mg)-GGAACF-3 was synthesised and utilised for the combine removal of metformin hydrochloride (MF) and diclofenac sodium (DCF). GG-g- P(AA)/CoFe2O4 (30 mg)-GGAACF-3 prepared using free radical initiator ammonium persulphate(APS), cross-linked using crosslinking agent N, N’- methylenebisacrylamide (MBA) and accelerator using tetramethyl ethylenediamine (TEMED). The GGAACF-3 exhibited high removal efficiency for DCF than MF. The highest removal efficiency for DCF and MF found to 82.17% and 69.26% at adsorbent dose 40 mg, neutral pH, room temperature (20°C) and contact time 24 h, respectively. Adsorption of both drugs followed the Langmuir adsorption isotherm and Pseudo- 2nd-order model kinetic model which indicated about homogeneous adsorption of both drugs on the surface of GGAACF-3 and chemisorption, respectively. The maximum adsorption capacity (qe) for MF and DCF determined to 123.60 mg/g and 120.7729 mg/g, respectively.

Research on the adsorption of Pb2+ ions and methylene blue dyes by a kapok and polypropylene fibre web

Purpose This study aims to investigate into the adsorption mechanism of heavy metal ions Pb2+ and methylene blue (MB) dyes on an adsorbent-web formed from kapok fibres (KP) and polypropylene fibres (PP). Design/methodology/approach Initially, the KP underwent pre-treatment with NaClO2 solution, and their morphology and structure changes were examined through scanning electron microscope images. Subsequently, the KP fibres were blended with PP fibres at a ratio of 70 / 30 and processed through a laboratory carding machine to form a fibre web, which was then secured using a heat press to fabricate the adsorbent-web. The resultant adsorbent-web was subjected to evaluation for the adsorption process. Findings The findings revealed that the adsorbent-web produced via the dry-laid method exhibited promising attributes, and the adsorption process conformed to the pseudo-second-order model and the Langmuir isotherm model. Parameters such as adsorbent-web porosity, solution pH, and adsorption thermodynamics exerted notable influences on the adsorption capacity of the adsorbent-web. Notably, the adsorbent-web demonstrated remarkable reusability and desorption capacity. In the fifth cycle, the adsorption capacity of adsorbent-web for MB and Pb2+ ions only decreased by 9.13% and 11.48%, respectively, compared to the first cycle. The desorption efficiency of the adsorbent-web exceeded 90% for MB and over 73% for Pb2+ ions. Originality/value This study makes a significant contribution to the practical application of KP as an adsorbent-web for treating waste from the textile dyeing industry.

Investigation on the Properties of Methyl 4-(((1-H benzo[d]imidazol-2-yl) methyl)thio)methyl)Benzoate on Aluminum Corrosion in Acidic Environment

Organic inhibitors are crucial for preserving metals from corrosion in acidic environments. In this regard, the methyl 4-(((1-H benzo[d]imidazol-2-yl)methyl)thio)methyl)benzoate (M-41HBI-2MTMB) was synthesized and investigated as an eco-friendly inhibitor for aluminum in a molar nitric acid solution (1 M HNO<sub>3</sub>). The gravimetric technique was used to study the inhibitory properties of the molecule, and the density functional theory (DFT) was conducted to elucidate the corrosion inhibition mechanism. The experimental data indicated that M-41HBI-2MTMB reduced the corrosion of the metal with a significant inhibition efficiency. The corrosion inhibition increased with an increase in the concentration of the molecule, reaching an efficiency of 98.5% at a concentration of 5.10<sup>-3</sup> M, and a temperature of 298 K. Adsorption isotherms and thermodynamic parameters were studied to elucidate the interactions between M-41HBI-2MTMB and the metal surface. The inhibitor adsorbed spontaneously onto the aluminum surface following the Villamil model (modified Langmuir isotherm). Additionally, the Gibbs free energy less than - 40 kJ.mol<sup>-1</sup> and the negative value of the enthalpy of adsorption suggested mixed-type adsorption with a predominance of physical interactions. The theoretical findings of DFT calculations revealed a positive fraction of electrons transferred (<i>ΔN = 0.247 eV</i>), a high value of the electrophilicity index (<i>ω = 3.807 eV</i>) as well as a low energy gap (<i>ΔE = 4.478 eV</i>) showing favorable interactions of M-41HBI-2MTMB with its environment. The active sites of the molecule were highlighted at the level of carbon atoms, and a corrosion inhibition mechanism was proposed.

Sustainable Adsorbent: Activated Carbon From Waste Styrofoam for Efficient Aluminum Removal.

This paper reports on batch investigations utilizing activated carbon (AC) made from waste Styrofoam to adsorb aluminum (Al3+) from aqueous solutions. The AC morphology and structure were examined using Fourier-transform infrared spectroscopy, scanning electron microscopy, and surface area analysis. The factors affecting the performance of adsorption were thoroughly examined. Al3+ removal was found to be maximal, that is, 98.65% using 0.2 g of AC at 90 min in a solution of pH 5 maintained at 60°C. Using a flame-mode atomic absorption spectrophotometer (AAnalyst 700, PerkinElmer, USA), the quantity of Al3+ in the adsorption solution was measured. For the purpose of studying adsorption, the pseudo-first-order, pseudo-second-order, Langmuir, Freundlich, Temkin, Jovanovich, and Harkins-Jura isotherms were analyzed. The kinetic study shows that the adsorption of Al3+ onto Al3+ is controlled by pseudo-second-order kinetics. It was observed that among these models, the Langmuir model showed the most favorable fit for the equilibrium data on the removal of Al3+ onto AC, with a strong fit (R2 = 0.995). The values of thermodynamic parameters such as entropy (ΔS°), Gibbs free energy (ΔG°), and enthalpy (ΔH°) show that the adsorption process is spontaneous and exothermic in nature. In Al3+ solutions with low concentrations, the AC exhibited a high adsorption rate. In addition, a check of the error function was performed. To find out if the AC could be utilized again after the adsorption procedure, desorption investigations were carried out. Due to its high adsorption capacity (> 98%) and porous structure, the prepared AC shows significant promise as an alternative adsorbent for Al3+. These findings demonstrate that the AC is both effective and efficient in removing Al3+ from wastewater.