Langmuir Isotherm Model Research Articles

Highly efficient phosphate adsorption using calcium silicate hydrate-embedded calcium crosslinked polyvinyl alcohol thin film

The removal of phosphate from water is necessary to avoid eutrophication. In this work, a novel composite film of calcium silicate hydrate (CSH) immobilized within calcium cross-linked polyvinyl alcohol (CSH–PVA) was developed for efficient phosphate removal from water using a simple and environmentally friendly preparation method. The characterization showed that flake crystal-like CSH nanoparticles were immobilized on a PVA film (86–106 μm). Amorphous calcium phosphate and hydroxyapatite were observed after phosphate adsorption. The adsorption efficiency and capability of phosphate were examined under various conditions using batch experiments. The phosphate removal data fitted well to the pseudo-second-order kinetic model (R2 = 0.9903–0.9999) and the Langmuir isotherm model (R2 = 0.9958), which estimated a maximum removal capacity (99.01 mg g−1). Phosphate adsorption was found to be endothermic with spontaneous adsorption via chemisorption with strong affinity (ΔG° = −3.96 to −8.62 kJ mol−1, ΔH° = 65.4 kJ mol−1, and ΔS° = 232.94 J mol−1 K−1). Additionally, significant amounts of fluoride and carbonate ions affected phosphate adsorption at levels exceeding 5-fold and 20-fold that of phosphate, respectively. An excellent removal efficiency was achieved in the range of 72.06%–97.87% using phosphate-containing real samples. Therefore, the proposed CSH–PVA film showed great potential for effective phosphate removal from water, with potential for further use as a fertilizer.

Intensification and characterization of biosorption of microalgal cells on filamentous fungal pellets as effective tools for harvesting of microalgal biomass

Microalgae are promising resources with a variety of advantages and applications. However, their harvesting cost in large-scale cultivation may account for 20–30 % and in some instances up to 50 % of the overall production cost. This study then aimed to apply biosorption of microalgal cells by using fungal pellets as an alternative low-cost and practical harvesting technique. Among the fungal strains screened, Aspergillus tubingensis TSIP9 formed spherical, mycelium packed and consistent in size. The biosorption of microalgal cells process was optimized through response surface methodology (RSM). The maximum harvesting efficiency of 98.3 ± 1.2 % was achieved when using pellet loading of 60 % and pH 5.0. The biosorption process can be explained by Langmuir isotherm model with the maximum biosorption capacity (qmax) of 0.338 g/g and the Langmuir constant (K) of 0.999 L/g. Pseudo-first-order model is suitable for describing the biosorption kinetics of microalgal cells on fungal pellets. The application of fungal pellets in downstream process for microalgae cultivation was attempted. The fungal pellets could harvest microalgal cells as high as 3.70 × 1011 cells/g after 5 cycles of repeated harvesting process. FTIR analysis revealed the possible functional groups involved in fungi-microalgae interaction are CO, CO, CN, and CH. These results indicated that the potential of fungal pellets as effective tools for harvesting/immobilizing microalgal cells and their practical applications in harvesting on a large scale and resource recycling.

Magnetic recyclable carboxymethyl cellulose/gelatin/citrate@Fe3O4 photo-nanocomposite beads for ciprofloxacin removal via hybrid adsorption/photocatalysis process under solar light as a renewable energy source

Magnetically separable cross-linked carboxymethyl cellulose/gelatin/citrate-functionalized magnetite nanoparticles (Cit-Fe3O4) photo-nanocomposite beads (mCMC/Ge) were synthesized and applied in synergistic adsorption/photocatalytic degradation of ciprofloxacin (Cipro) pharmaceutical pollutant under sunlight irradiation. Various analytical techniques were employed to characterize their structural, textural, magnetic, thermal, and optical properties. The removal efficiency of mCMC/Ge beads was investigated considering different influencing parameters (pH, beads dosage, contact time, Cipro concentration, and temperature). Experimental data modeling indicated that the adsorption process followed pseudo-second-order kinetics and Langmuir isotherm models, with a maximum Langmuir adsorption capacity (qm) of 50 mg g−1 for mCMC/Ge, twice that of the matrix. Photocatalytic activity results showed prominent enhancement in Cipro removal using 1 g L−1 of mCMC/Ge at pH 7, as compared to Cit-Fe3O4, reaching 96 %, 85 %, and 63 % after 180 min of adsorption and 120 min of irradiation for initial pollutant concentrations of 10, 20, and 60 mg L−1, respectively. Furthermore, mCMC/Ge demonstrated efficient removal even in real water sample.The excellent removal performance of mCMC/Ge highlighted the synergy between polymeric matrix template and encapsulated Cit-Fe3O4 in improving Cipro adsorption and photodegradation. Furthermore, facile recyclability and sustained activity over five cycles identify mCMC/Ge photo-nanocomposite as a promising material for removing organic pollutants from contaminated waters.

Synthesis, Characterization, Theoretical, and evaluation of Eco-Friendly benzimidazolylmethyl-pyrazole carboxylate Schiff Bases corrosion inhibitors for mild steel

In this study, benzimidazolylmethyl-pyrazole carboxylate derivatives were synthesized via a 1,3-dipolar cycloaddition reaction and characterized using IR, HRMS and NMR spectroscopy. Three derivatives, namely ethyl 5-((3-(cyclohex-1-en-1-yl)-2-oxo-2,3-dihydro-1H-benzo[d]imidazol-1-yl)methyl)-1-phenyl-1H-pyrazole-3-carboxylate (Ph-BPC), ethyl 5-((3-(cyclohex-1-en-1-yl)-2-oxo-2,3-dihydro- 1H-benzo[d]imidazol-1-yl)methyl)-1-(p-tolyl)-1H-pyrazole-3-carboxylate (CH3Ph-BPC), and ethyl 1-(4-chlorophenyl)-5-((3-(cyclohex-1-en-1-yl)-2-oxo-2,3-dihydro-1H-benzo[d]imidazol-1-yl)methyl)-1H-pyrazole-3-carboxylate (ClPh-BPC), were evaluated as corrosion inhibitors for mild steel (MS) in a 1 M HCl solution. Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) measurements revealed high inhibition efficiencies of 98.5 %, 98.2 %, and 97.7 % for ClPh-BPC, Ph-BPC, and CH3Ph-BPC, respectively, at a concentration of 10-4 M. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses confirmed the formation of protective surface layers, significantly reducing corrosion rates. Thermodynamic analysis indicated that the adsorption of these inhibitors follows the Langmuir isotherm model with adsorption energies of −50.12 kJ/mol for ClPh-BPC, −50.52 kJ/mol for Ph-BPC, and −51.62 kJ/mol for CH3Ph-BPC, suggesting chemisorption. Computational studies, including Monte Carlo (MC), density functional theory (DFT), and molecular dynamics (MD) simulations, showed strong agreement with experimental results, further validating the adsorption behavior and corrosion inhibition mechanisms of these compounds.

Elimination of Cd2+ from synthetic and real polluted water by optimized Acacia nilotica biographene

Biographene was prepared through the pyrolysis of Acacia nilotica waste using diverse temperatures and time spans. The obtained materials were characterized using scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDX), X-ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR) methods. The data obtained indicated that when the temperature and time increased, the texture of the biographene became more porous with greater carbon content. The effect of various variables on Cd(II) adsorption, using the optimized biographene product, was investigated, and the results revealed that the optimum pH was 4 and the maximum adsorption capacity was 118.9 mg/g. The Langmuir isotherm model and pseudo-second-order kinetic model best fit the equilibrium data, indicating the adsorptive behavior of the as-prepared biographene implying a homogenous monolayer surface. The recyclability investigation elucidates the remarkable potentiality of up to five consecutive cycles. As such, the biographene-based Acacia nilotica could be considered a sustainable candidate for cadmium removal from polluted water.

Zeolite-based absorbent: Polyacrylic acid loading for enhanced ferric(III) removal from aqueous solution

The process of adsorption shows promise as an effective method for water purification due to its cost-effectiveness, reusability, and adaptability in treating various metal ions. However, it has been noted that this method has limited Fe(III) removal capacity and is susceptible to interference from co-existing ions. To address this, a new adsorbent material (ZEO-PAA) was developed by loading polyacrylic acid (PAA) onto NaOH-treated zeolite using γ-Glycidoxypropyltrimethoxysilane (GPTMS) as a linker. In comparison to natural zeolite, ZEO-PAA demonstrates a strong affinity for Fe(III), exhibiting remarkable Fe(III) removal performance even in the presence of other common cations, such as Na(I), Ca(II), and Mg(II). Furthermore, ZEO-PAA maintains high adsorption performance for heavy metal ions such as Pb(II), Cu(II), Ni(II), Cd(II), and Cr(III). After 7 cycles of adsorption/regeneration, the Fe(III) removal rate of ZEO-PAA remains over 85 %. The adsorption process of ZEO-PAA for Fe(III) aligns with the Langmuir isotherm model and PSO Kinetics model, with a maximum adsorption capacity (qm) of 37.53 mg/g. This study provides valuable insights into the development of a reusable adsorbent material, demonstrating great potential for practical water treatment.

Corn stover waste preparation cerium-modified biochar for phosphate removal from pig farm wastewater: Adsorption performance and mechanism

The high phosphorus content in livestock and poultry wastewater is a significant factor contributing to water eutrophication. It is imperative to seek an economically efficient method for phosphate recovery. This study employed cerium-modified biochar to recover phosphate from pig farm wastewater. An investigation was conducted to examine the adsorption performance and removal mechanism of phosphate. Among the different samples, 0.1CeB-500℃ was selected for subsequent experiments. It exhibited a phosphate adsorption capacity of 9.58 mg/g and a removal efficiency of 95.75 %. The results showed that the phosphate adsorption process followed not only the pseudo-second-order kinetic model, but also the Langmuir isotherm model. It suggested that the adsorption of phosphate onto the biochar occurred in a monolayer chemical manner, with a maximum adsorption capacity of 10.86 mg/g. Phosphate adsorption was minimally affected within the pH range of 2–9, with Cl- having negligible impact, NO3- slightly inhibiting, and HCO3- and CO32- significantly hindering phosphate adsorption. A series of characterization results indicated that phosphate removal occurred through surface precipitation forming CePO4, ligand exchange between carbonate and phosphate, inner-sphere complexation, and electrostatic attraction. The phosphate removal efficiency from pig farm wastewater was 43.25 %, demonstrating promising potential for practical application.

Insight into enhanced adsorption of Congo red by petal-like MgAl2O4: effect of dehydroxylation

This paper reports a facile treatment to enhance the capacity of petal-like MgAl2O4 for Congo red (CR) adsorption. The influence of dehydroxylation treatment on the adsorption performance of petal-like MgAl2O4is investigated. FT-IR, XPS, TG, XRD and FE-SEM are employed to analyze the differences between samples without and with dehydroxylation. Mechanism on the adsorption capacity improvement of CR by MgAl2O4 after dehydroxylation is investigated systematically. Results show that the adsorption process conforms well to the pseudo-second-order kinetic model and Langmuir isotherm model. The adsorption mechanism study shows that the adsorption of CR on petal-like MgAl2O4is mainly due to chemisorption including Lewis acid-base interaction and electrostatic attraction. It is observed that the maximum adsorption capacity of petal-like MgAl2O4after dehydroxylation reaches 3264.54 mg/g, much higher than sample without dehydroxylation (591.72 mg/g). Most Lewis acid sites of petal-like MgAl2O4 (Mg2+ and Al3+) without dehydroxylation process are occupied by hydroxyl groups. It is not conductive to combine with NH2- and -SO32- in CR molecular, resulting in the deterioration of adsorption performance. The activity of Mg2+ and Al3+ in MgAl2O4 can be recovered greatly after the removal of hydroxyl groups, and it is favorable to the adsorption between MgAl2O4 and CR.

Coconut shells based MrGO@CMC adsorbent for the chromium (VI) ion removal from contaminated water through batch adsorption method

The chromium (III) ion is necessary for biological function and the chromium (VI) ion (Cr (VI)) induces toxicity to humans and animals. From the sources of industries, the contaminated Cr (VI) is an important issue to remove from the solution. Here, we synthesized magnetic reduced graphene oxide @ carboxymethyl cellulose (MrGO@CMC) adsorbent for the removal of Cr (VI) from aqueous solution. The fabricated adsorbent was characterized through XRD, FT-IR, SEM, EDX, BET, VSM, and TGA. Adsorption studies were conducted various parameters and the optimized contact time, dosage and concentration was fixed such 60 min and 10 mg L−1 respectively. By the MrGO@CMC adsorbent almost 93% efficiency Cr (VI) was removed from the aqueous solution at 40 min, 25 mg, 10 mg L−1, and neutral pH. The zero point charge (pHzpc) of the adsorbent was observed at pH-6.3. The MrGO@CMC adsorbent followed Langmuir isotherm model at achieving a maximum adsorption capacity of 625.8 mg g−1 and it indicates chemisorption dominated monolayer adsorption and the system follows pseudo-second-order kinetics model indicating a bimolecular system. Thermodynamic analysis revealed that the adsorption process was endothermic and spontaneous reaction. The adsorbent regeneration and reusability studies demonstrated that MrGO@CMC retained over 70.90% efficiency in removing Cr (VI) ions even after five recovery cycles compare with other graphene oxide-based adsorbent, the current adsorbent have potential removal efficiency, since the proposed adsorbent shows excellent adsorbent for Cr (VI) ions from industrial wastewater.

U(Ⅵ) sorption by porous sodium zirconium phosphate pellets from aqueous solution

Zirconium phosphate is the first artificially produced layered phosphate that can sorb a variety of nuclides from solutions. Sodium zirconium phosphate (NZP) was a type of α-zirconium phosphate (α-ZrP). The porous sodium zirconium phosphate pellets (p-NZP-P) with a diameter of more than ∼3 mm were prepared and used for uranium sorption. The p-NZP-P could be immersed in solutions for more than 5 days without dissolving and structurally collapsing. The sorption properties of U(Ⅵ) on p-NZP-P in solutions were investigated by both static and dynamic sorption tests. Synthetic p-NZP-P was analyzed in detail using various characterizations to investigate their character and structural changes. In the static sorption experiment, the equilibrium sorption capacity reached the 77.5 ± 1.5 mg·g−1 when the initial concentration of U(Ⅵ) was 100 mg/L, pHinitial = 4.5, T = 25 ℃. Uranium sorption increased by ∼69 % and ∼215 %, respectively, when the initial uranium concentration was increased from 100 to 300 mg·L−1 and the temperature was increased from 15 to 55 °C. Furthermore, uranium sorption increased by ∼541 % when the initial pH increased from 2.5 to 4.5, while it decreased by ∼39 % when the initial pH increased from 4.5 to 7.0. The sorption data corresponded to the pseudo-second-order kinetic model and the Langmuir isotherm model, as well as the theoretically predicted value of sorption capacity (∼199.9 mg·g−1). The results of the dynamic sorption experiment showed that decreasing the quality, increasing the flow rate and the initial U(Ⅵ) concentration would shorten the breakthrough time. The dynamic sorption data agreed well with the Thomas model. The characterization confirmed the porous properties, while the U(Ⅵ) sorption mechanisms relate to –OH coordination and ion exchange. A radioactive rare earth wastewater treatment test suggested that p-NZP-P could be the potential uranium sorbent due to its good stability and efficiency. This paper opened opportunities for the development of practical materials for treating radioactive wastewater in the application of actual scenarios.

Surface functionalization of XC18 steel using a new transition metal complex for remarkable corrosion performance: Empirical and theoretical studies

Synthesis of transition metal complexes (TMC) having specific characteristics is advantageous for combining their organic and inorganic properties, to help prevent metals from corrosion. In this study, the corrosion inhibition behavior of [N, N’-bis(salicylidene)-2,2-dimethyl-1,3-propanediaminato] copper (II) (CuL) on the surface of XC18 steel surface immersed in 1.0 M HCl was investigated. The thermodynamic and kinetic corrosion parameters were determined using the mass loss (ML) and electrochemical measurement methods. CuL exhibited a good corrosion inhibition efficiency of 96.72 %. The adsorption behavior of CuL followed the Langmuir isotherm model, indicating both physical and chemical interactions. Morphological structural analysis demonstrated that CuL formed a protective film between the surface of XC18 steel and the corrosives elements, thus confirming its adsorption onto XC18 steel surface. Theoretical calculations were consistent with the experimental findings, thereby confirming that the adsorption of CuL onto the steel surface comprises both physisorption and chemisorption processes. These calculations elucidate the specific bonding nature and emphasize the significant inter- and intra-molecular interactions that enhance the stability and adsorption capability of the CuL inhibitor. The successful formation of a protective layer on the surface of XC18 steel using a TMC signifies exciting prospects for the development of advanced materials with diverse applications.

Sctudies on adsorption of Brilliant Green from aqueous solution onto nutraceutical industrial pepper seed spent

The study proposed the removal of Brilliant Green, a cationic dye, by adsorption process from wastewater solution utilizing a low-cost adsorbent such as Nutraceutical Industrial Pepper Seed Spent (NIPSS). The study comprises an investigation of the parametric influence on the adsorption process. The parameters identified are pH, dye concentration, process temperature, quantity of the adsorbent, and particle size. The study of statistics found from experiments was carried out by incorporating Freundlich, Brouers-Sotolongo, Langmuir, Toth, Sips, Jovanovic, and Redlich-Peterson isotherm models. The adsorption kinetics were determined by implementing pseudo-first-order and second-order models, diffusion film models, and Dumwald-Wagner and Weber-Morris models. The experimental adsorption capacity qe was found to be about 130 mg/g. This value was closest to the maximum adsorption of 144.6mg/g predicted by the Brouers-Sotolongo isotherm which had a correlation coefficient (R2) of 0.998. The adsorption kinetics data was confirmed to be a pseudo-second-order model. The change in free energy, enthalpy change, and entropy change were vital thermodynamic factors in concluding that adsorption is almost spontaneous and endothermic process. Change in enthalpy (ΔH°) reduced value indicates the physical nature of the process. The adsorption of BG dye on the adsorbent surface was authenticated by FTIR spectroscopy and SEM imaging. A Central Composite Design (CCD) Quadratic model under Response Surface Methodology (RSM) was implemented for statistical optimization of adsorption capacity for the five parameters studied, namely, time, temperature, concentration of the dye, weight of the adsorbent, and pH. Software Design Expert 7.0 was used to evaluate 3D contour plots. The process of optimization yielded a value of 350 mg/g. Thus, incrementing the adsorption process by 84.2 %. The study provides insights on various dye and adsorbent interaction possibilities and derives that NIPSS is an efficient adsorbent to extract BG dye from wastewater solutions.

Exploration of the role of Hibiscus esculentus (okra) mucilage for the removal of phenothiazinium dyes from water body: Spectroscopic, thermodynamic and molecular modeling study

Environmental pollution poses a major problem now a day. Several dyes, in the form of industrial waste, pollute water body and may cause adverse effects to human health. In this paper ADME and toxicity of fives Phenothiazinium group of dyes Methylene blue (MB), Azure A (AA), Azure B (AB), Azure C (AC) and Toluidine Blue O (TBO) were predicted using Swiss ADME and Protox II tools. Results showed these dyes may herm for living organism due to their carcinogenic, mutagenic and hepatotoxic properties. Removal efficiency of these dyes using okra plant product were determined using spectroscopic, thermodynamic and molecular modeling study. It was revealed that these dyes adsorb on the surface of okra leaf mostly at pH 7.0 and the adsorption isotherms were found to fit in Langmuir and Freundlich isotherm model, while Temkin model fails to do this. Mucilage present in different parts of okra plant plays a significant role on removal of these dyes and is able to remove near about 71–92 % of dyes from water body by itself. As this process did not fit in any of above said adsorption isotherm model, it may be suggested that some other mechanism may happen. Further studies explore that these dyes bound to the hydrophobic pocket of mucilage with binding affinity in the order of 105 M−1 and the bindings were exothermic in nature with enthalpy change in the range of − 2.94 to − 4.28 kcal/mole. Molecular docking study validate all the experimental results obtained from spectroscopic and thermodynamic study and enlighten the role of structure of dyes on their binding affinity to mucilage. This paper will help to systematically understand the role of okra plant products on removal efficiency of Phenothiazinium group of dyes with their structural variations.

Mesoporous TiO2@nitrogen-doped carbon nanosheets implanted in flexible and robust chitosan membrane with dual-function for efficient adsorption of iodide and methyl orange from aqueous solution

Radioactive iodide (I−) and methyl orange (MO) are two leading pollutants in wastewater, posing significant health risks. Crosslinked chitosan membranes (CCM) combined with TiO2@nitrogen-doped carbon nanosheets (CCM/TiO2@NC) were prepared as efficient I− and MO adsorbents in wastewater. These membranes leverage multiple interactions between I−/MO and functional groups (−NH2, nitrogen-doped carbon, and TiO2) within the membrane. As expected, CCM/TiO2@NC exhibited high I− removal efficiencies of nearly 82 % across a wide pH range (pH 3 − 11) and an exceptional MO removal efficiency of 96.1 % at a neutral condition. The adsorption behaviors followed the Langmuir isotherm and pseudo-second order kinetic model for both species, achieving maximum adsorption capacities of 1.383 mmol/g (175.6 mg/g) for I− and 661.4 mg/g for MO, respectively. Additionally, CCM/TiO2@NC maintained a high absorption efficiency for both I− and MO through five regeneration cycles. The I− adsorption mechanism of CCM/TiO2@NC involves electrostatic attraction, anion-π interaction, and hydrogen bonding, while MO adsorption involves electrostatic attraction, n/π-π interactions, and hydrogen bonding. This study offers feasible guidance on developing chitosan/nanomaterial composites as promising adsorbents for removing I− and MO from wastewater.

Efficient adsorption of flavonoids on amino-functionalized ZIF-8/chitosan aerogels

Covalent organic structures (MOFs), known for their exceptional properties in separation and purification, have garnered significant attention. However, applying MOF-based adsorbents in complex flavonoid separation scenarios remains challenging. In this study, we successfully synthesized adsorbent materials capable of efficiently adsorbing flavonoids using a vacuum freeze-drying method. The materials were derived from a cross-linked chitosan aerogel functionalized with amino-substituted zeolite imidazolium ester skeleton (ZIF-8). The ZIF-8-NH2, synthesized via in situ substitution of 2-aminobenzimidazole within the ZIF-8 framework, exhibits a smaller pore size than mono ligand ZIF-8. Due to its synergistic interaction with chitosan's biocompatibility and porous structure, the aerogel material (ZIF-8-NH2/CS) exhibited outstanding adsorption capacities (183.37 mg/g, 226.34 mg/g, and 187.16 mg/g) in standard solutions (T = 318 K, rpm = 200) of luteolin, quercetin, and rutin, along with high adsorption rates (71.3 ± 2.3 %, 72.4 ± 1.4 %, and 70.7 ± 3.5 %). And showed rapid adsorption in the first 60 min. After 5 cycles, the adsorption capacity of ZIF-8-NH2/CS aerogel remained at 80.5 % of the adsorption capacity of the initial cycle, and therefore, ZIF-8-NH2/CS aerogel has a good potential for reusability. Additionally, the adsorption process adhered to pseudo-first-order and pseudo-second-order kinetic models, alongside Langmuir and Freundlich isothermal adsorption models. This study introduces novel ideas and methods for the extraction and separation of flavonoids. Furthermore, the developed ZIF-8-NH2/CS aerogels with amino functionality hold promise for diverse applications in separating and purifying bioactive substances.

WITHDRAWN: Studies on decontamination of cadmium rich water by a novel nano Iron oxide adsorbent

Synthesizing non-toxic adsorbent for abatement of hazardous pollutants from water is important to develop safe environment. In this study, nanocrystalline iron oxide particles were synthesized and utilized as effective nanoadsorbent for removing cadmium through adsorption. The as-prepared nanoadsorbent was characterized using sophisticated techniques. The objective of this study was to improve cadmium adsorption from aqueous solutions under a variety of conditions. With the help of Box-Behnken design, adsorption parameter settings were improved. Response Surface Methodology analysis was conducted to optimize the adsorption conditions, including pH, initial concentration of metal ions, and adsorbent dose. Comparisons were made between the optimal equations for linear and non-linear kinetics, along with isotherm models. Origin's curve fitting tool and the Solver add-in of Microsoft Excel are two non-linear analytical tools. The obtained results showed that the Origin curve fitting tool is superior to solver add in's error analysis method for determining isotherm parameters. The equilibrium data for cadmium removal using nano iron oxide/hydroxide adsorbent was best fitted to Langmuir isotherm model. The adsorption of cadmium was well described by the pseudo-second-order model. The study shows that the system appears to be spontaneous according to the Langmuir constant method and thermodynamic parameter via partition.

Eco-friendly corrosion inhibition of copper in NaCl media using Perseana americana extract: Insights from quantum and electrochemical studies

Corrosion of copper in saline environments, particularly in 3.5% sodium chloride (NaCl) solutions, poses significant challenges across various industries, leading to substantial economic losses and safety concerns. Traditional corrosion inhibitors, often synthetic and toxic, raise environmental issues that necessitate the exploration of sustainable alternatives. This study investigates the use of Perseana americana extract (PAE) as an eco-friendly inhibitor for copper corrosion, demonstrating an impressive inhibition efficiency of 96.53% at an optimal concentration of 300 mg/L. Electrochemical assessments, including potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), reveal that PAE functions as a mixed-type inhibitor, significantly reducing the corrosion current density (icorr) from 3.59 × 10⁻⁵ A/cm2 (without inhibitor) to 1.83 × 10⁻⁵ A/cm2 at 100 mg/L, and further to 0.12 × 10⁻⁵ A/cm2 at 300 mg/L. The adsorption behavior of PAE on the copper surface adheres to the Langmuir isotherm model, indicating monolayer adsorption with a Gibbs free energy of adsorption (ΔGads) of −18.84 kJ/mol, suggesting a predominantly physisorption mechanism. Additionally, Monte Carlo simulations confirm strong interactions between PAE molecules and the copper surface, with the highest adsorption energy recorded for phloretin at −3778.338 kcal/mol, highlighting the extract's potential as a green alternative to conventional inhibitors. This research underscores the viability of utilizing natural plant extracts for effective corrosion control, contributing to more sustainable practices in metal protection.

Effect of HEDTA on the Adsorption of 2,2 Bipyridyl and 3-Mercaptobenzothiazole and Electroless Cu Deposition Rate

Surface-enhanced Raman spectroscopy (SERS) and chronoamperometry were utilized to evaluate the electroless deposition of Cu in hydroxyethylethylelenediaminetriacetic acid (HEDTA)- and tartrate-based baths containing 2,2′-bipyridyl (BP) and 2-mercaptobenzothiazole (MBT). The Cu deposition rate was shown to be faster in tartrate baths, with rates at 0.08 μm min−1 without MBT or BP but decreased to near zero with concentrations approaching 6 μM of either MBT or BP. HEDTA baths displayed a slower rate of 0.04 μm min−1 without MBT or BP. However, the addition of MBT increased the rate up to 4-fold, while BP concentration did not affect the deposition rate. SERS data showed that HEDTA adsorbs to the surface while tartrate does not. Kinetic Langmuir isotherm model fits showed a decrease in MBT and BP adsorption rate in the presence of HEDTA and showed a decrease in HEDTA adsorption upon MBT injection while BP injection did not affect the HEDTA adsorption. Competition between the complexing and the stabilizing agent is a key factor for the rate of electroless Cu deposition.

Removal of 4-(2-pyridylazo) resorcinol and Arsenazo-III from liquid waste solutions using Penicillium oxalicum: Gamma irradiation studies

The current investigation involved the isolation of a fungal strain from liquid radioactive wastewater, which was then identified as Penicillium oxalicum and was employed to remove 4-(2-pyridylazo) Resorcinol (PAR) and Arsenazo-III (Ar-III) from liquid waste solutions. The physicochemical properties of the biosorbent fungi were analyzed using SEM and FT-IR. The biosorption effectiveness of PAR and Ar-III was investigated under several experimental settings, including pH values, adsorption times, biosorbent weight, initial dye concentrations, and reaction temperatures. The Langmuir isotherm model describes the adsorption isotherms well, with capacities of 10.88 and 11.96mgg-1 for PAR and Ar-III, respectively. The sorption of PAR and Ar-III exhibited E values of 19.84 and 17.84kJ/mol, respectively, indicating that the process is chemical adsorption. The pseudo-second-order kinetic model was determined as the most accurate representation of the biosorption kinetics. Both film diffusion and intra-particle diffusion describe the diffusion of coloring reagents through the biosorbent material. The thermodynamic analysis showed that chemical adsorption regulated the biosorption of the coloring reagent on the biosorbent material, while exothermic and spontaneous biosorption of PAR and Ar-III was observed. The extensive decolorization and easy operating circumstances demonstrated the promise of Penicillium oxalicum for the biological treatment of textile dyes.

Remarkable adsorptive capacity and reusability performance of magnetic magnetite@silica@L-histidine nanocomposite towards gaseous benzene pollutant

Herein, magnetic magnetite@silica@L-histidine (Fe3O4@SiO2@L-Hist) core-shell nanoparticles (NPs) as novel adsorbents were first prepared via chemical co-precipitation and sol-gel technology for the adsorption of gaseous benzene pollutant. The Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@L-Hist NPs were characterized using a combination of scanning electron microscopy (SEM), SEM - energy dispersive X-ray (SEM-EDX), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), Brunauer-Emmett-Teller analysis (BET), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). The adsorption capacities of Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@L-Hist NPs for benzene were found to be 188, 279 and 481 mg g-1, respectively, with Fe3O4@SiO2@L-Hist NPs demonstrating the highest capacity. Kinetic and isotherm studies indicated that the pseudo-2nd-order kinetic model and the Langmuir isotherm model provided the best fit to the experimental data, suggesting favorable physical adsorption. In addition, Fe3O4, Fe3O4@SiO2 and Fe3O4@SiO2@L-Hist NPs exhibited remarkable reusability, with reuse efficiencies of 85.67, 89.65 and 91.73%, respectively, after five recycle cycles, demonstrating their potential for practical benzene remediation applications. Overall, this study offers valuable insights into creating effective and sustainable adsorbents for eliminating volatile organic compounds (VOCs). This contributes to mitigating air pollution and safeguarding both human health and the environment.