New Azo Derivative of ß-Diketones and Its Cu(II), Co(II) Complexes: Synthesis, Theoretical Study and Biological Activity.

The paper is focused on biological activity and theoretical study of the structure and properties of a new azo derivative of ß-diketones and its complexes with some metals. The aim of our work was to study the structure and properties of the newly synthesized compound as well as to theoretically determine the possibility of complex formation with the Cu(II) or Co(II) ions. A compound with the same substituents R1=R2=CH3 was chosen for the study. A synthesized azo compound based on 4-amino antipyrine and its complexes with Cu(II), Co(II) in solution and solid phase is reported. The structures of these compounds have been testified by X-ray, IR and  NMR spectroscopy. The combined experimental and theoretical approach was used. To study the structure and properties of the synthesized compound, as well as its possible complex formation with the Cu(II), quantum-chemical calculations were carried out the 6-31G basis set and the electron density functional theory (DFT) method. These 3-(1-phenyl-2,3-dimethyl-pyrazolone-5) azopentadione-2,4 (PDPA) with Cu(II) and Co(II) complexes had effective inhibition against butyrylcholinesterase and acetylcholinesterase. IC50 values were found as 19.03, 3.64 µM for AChE and 28.47, 8.01 µM for BChE, respectively. Cholinesterase inhibitors work to slow down the acetylcholine's deterioration.

Selective Nsp2 - and Csp2 - Photografting of Au-Surface by Aryldiazonium Salts and Arylazo Sulfonates.

Arylazo sulfonates (Ar-N=N-SO3 Na) have been found to undergo photografting on gold surface through both Au-Nsp2 - and Au-Csp2 - bond formation. The functionalized materials have been fully characterized by infrared reflection absorption spectroscopy (IRRAS), Raman, XPS, DFT calculations and UV-Vis absorption spectroscopy. These methods permit to evidence aromatic substituents (IRRAS), the Au-N=N signature (Raman and XPS spectroscopy), and the bond dissociation energy values of the two linkages (DFT calculation). The grafting proceeds through two competitive paths, namely a stepwise reaction involving an aryl radical (for the formation of the Au-Ar bonds) and a concerted reaction on the surface of gold (for Au-N=N-Ar bond formation). The occurrence of an aryl radical upon irradiation has been fully evidenced by EPR spectroscopy. Finally, E/Z photoisomerisation of the N=N bonds present on prepared few layer films has been observed by means of UV-Vis absorption spectroscopy.

Coco Monoethanolamide Surfactant as a Sustainable Corrosion Inhibitor for Mild Steel: Theoretical and Experimental Investigations.

Recent studies indicate that surfactants are a relatively new and effective class of corrosion inhibitors that almost entirely meet the criteria for a chemical to be used as an aqueous phase corrosion inhibitor. They possess the ideal hydrophilicity to hydrophobicity ratio, which is crucial for effective interfacial interactions. In this study, a coconut-based non-ionic surfactant, namely, coco monoethanolamide (CMEA), was investigated for corrosion inhibition behaviour against mild steel (MS) in 1 M HCl employing the experimental and computational techniques. The surface morphology was studied employing the scanning electron microscope (SEM), atomic force microscope (AFM), and contact measurements. The critical micelle concentration (CMC) was evaluated to be 0.556 mM and the surface tension corresponding to the CMC was 65.28 mN/m. CMEA manifests the best inhibition efficiency (η%) of 99.01% at 0.6163 mM (at 60 °C). CMEA performs as a mixed-type inhibitor and its adsorption at the MS/1 M HCl interface followed the Langmuir isotherm. The theoretical findings from density functional theory (DFT), Monte Carlo (MC), and molecular dynamics (MD) simulations accorded with the experimental findings. The MC simulation's assessment of CMEA's high adsorption energy (-185 Kcal/mol) proved that the CMEA efficiently and spontaneously adsorbs at the interface.

Theoretical, Equilibrium, Kinetics and Thermodynamic Investigations of Methylene Blue Adsorption onto Lignite Coal.

The interaction of methylene blue (MB) dye with natural coal (collected from coal landfills of the Kosovo Energy Corporation) in aqueous solutions was studied using adsorption, kinetics, and thermodynamic data, and Monte Carlo (MC) calculations. In a batch procedure, the effects of contact duration, initial MB concentration, pH, and solution temperature on the adsorption process were examined. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) isotherms were used to examine the equilibrium adsorption data. The equilibrium data fit well to the Freundlich and Langmuir adsorption isotherm models; however, the Freundlich model suited the adsorption data to a slightly better extent than the Langmuir model. The kinetics experimental data was fitted using pseudo-first-order, first-order, pseudo-second-order, second-order, Elvoich equation, and diffusion models. The pseudo-second-order rate model manifested a superlative fit to the experimental data, while the adsorption of MB onto coal is regulated by both liquid film and intraparticle diffusions at the same time. Thermodynamic parameters, such as Gibbs free energy (ΔG0), enthalpy (ΔH0), and entropy (ΔS0) were calculated. The adsorption of MB was confirmed to be spontaneous and endothermic. The theoretical results were in agreement with the experimental ones.

Cellulose-Based Hectocycle Nanopolymers: Synthesis, Molecular Docking and Adsorption of Difenoconazole from Aqueous Medium.

The goal of this work was to develop polymer-based heterocycle for water purification from toxic pesticides such as difenoconazole. The polymer chosen for this purpose was cellulose nanocrystalline (CNC); two cellulose based heterocycles were prepared by crosslinking with 2,6-pyridine dicarbonyl dichloride (Cell-X), and derivatizing with 2-furan carbonyl chloride (Cell-D). The synthesized cellulose-based heterocycles were characterized by SEM, proton NMR, TGA and FT-IR spectroscopy. To optimize adsorption conditions, the effect of various variable such as time, adsorbent dose, pH, temperature, and difenoconazole initial concentration were evaluated. Results showed that, the maximum difenoconazole removal percentage was about 94.7%, and 96.6% for Cell-X and Cell-D, respectively. Kinetic and thermodynamic studies on the adsorption process showed that the adsorption of difenoconazole by the two polymers is a pseudo-second order and follows the Langmuir isotherm model. The obtained values of ∆G ° and ∆H suggest that the adsorption process is spontaneous at room temperature. The results showed that Cell-X could be a promising adsorbent on a commercial scale for difenoconazole. The several adsorption sites present in Cell-X in addition to the semi crown ether structure explains the high efficiency it has for difenoconazole, and could be used for other toxic pesticides. Monte Carlo (MC) and Molecular Dynamic (MD) simulation were performed on a model of Cell-X and difenoconazole, and the results showed strong interaction.

Alkyl-Modified Gold Surfaces: Characterization of the Au-C Bond.

The surface of gold can be modified with alkyl groups through a radical crossover reaction involving alkyliodides or bromides in the presence of a sterically hindered diazonium salt. In this paper, we characterize the Au-C(alkyl) bond by surface-enhanced Raman spectroscopy (SERS); the corresponding peak appears at 387 cm-1 close to the value obtained by theoretical modeling. The Au-C(alkyl) bond energy is also calculated, it reaches -36.9 kcal mol-1 similar to that of an Au-S-alkyl bond but also of an Au-C(aryl) bond. In agreement with the similar energies of Au-C(alkyl) and Au-S-(alkyl), we demonstrate experimentally that these groups can be exchanged on the surface of gold.

Some Theoretical and Experimental Insights on the Mechanistic Routes Leading to the Spontaneous Grafting of Gold Surfaces by Diazonium Salts.

The spontaneous grafting of diazonium salts on gold may involve the carbocation obtained by heterolytic dediazonation and not necessarily the radical, as usually observed on reducing surfaces. The mechanism is addressed on the basis of DFT calculations and experiments carried out under conditions where the carbocation and the radical are produced selectively. The calculations indicate that the driving force of the reaction leading from a gold cluster, used as a gold model surface, and the carbocation to the modified cluster is higher than that of the analogous reaction starting from the radical. The experiments performed under conditions of heterolytic dediazonation show the formation of thin films on the surface of gold. The grafting of a carbocation is therefore possible, but a mechanism where the cleavage of the Ar-N bond is catalyzed by the surface of gold cannot be excluded.

Surface Modification of Lignite with Alkyl and Mixed Alkyl-Aryl Films Generated from an Aryl Diazonium Salt and Alkyl Halides: Experimental Results and Theoretical Analyses.

In search of new possible uses of cheap lignite from the Kosova Bassin, the surface of lignite powders is modified with alkyl or mixed alkyl-aryl layers. Modification is performed in aqueous acid solution containing an aryl diazonium salt and an alkyl halide compound in millimolar concentration, in the presence of potassium iodide as a reducing agent at equimolar concentration. Attachment of alkyl films substituted with carboxylic groups and aryl films with nitro or bis-trifluoromethyl groups is characterized by IRATR and XPS spectroscopy. The formation of a stable interface during the grafting reactions of alkyl and aryl moieties with lignite surface has been confirmed by theoretical calculations. Aryl diazonium salts once chemically or spontaneously reduced are a source of aryl radicals, able to attach chemically to the material surface or to react with alkyl halides by abstracting the halogen atom. If the aryl diazonium salts are unable to graft to the coal surface due to steric hindrance, they can, nevertheless, abstract an iodine or bromine atom to generate alkyl radicals that react with the material surface.

Unraveling the corrosion inhibition behavior of prinivil drug on mild steel in 1M HCl corrosive solution: insights from density functional theory, molecular dynamics, and experimental approaches.

The deterioration of mild steel in an acidic environment poses a significant challenge in various industries. The emergence of effective corrosion inhibitors has drawn attention to studies aimed at reducing the harmful consequences of corrosion. In this study, the corrosion inhibition efficiency of Prinivil in a 1M HCl solution through various electrochemical and gravimetric techniques has been investigated for the first time. The results demonstrated that the inhibition efficiency of Prinivil expanded from 61.37% at 50 ppm to 97.35% at 500 ppm concentration at 298 K. With a regression coefficient (R 2) of 0.987, Kads value of 0.935 and Ea value of 43.024 kJ/mol at 500 ppm concentration of inhibitor, a strong affinity of Prinivil for adsorption onto the metal surface has been significantly found. Scanning electron microscopy (SEM) and contact angle measurement analyses further support the inhibitory behavior of Prinivil, demonstrating the production of a defensive layer on the surface of mild steel. Additionally, molecular dynamics (MD) and Monte Carlo simulations were employed to investigate the stability and interactions between Prinivil and the metallic surface (Fe (1 1 0)) at the atomic level. The computed results reveal strong adsorption of Prinivil upon the steel surface, confirming its viability as a corrosion inhibitor.

Experimental accompanied with computational (atomic/electronic)-level simulation investigations of Polygonum cuspidatum root extract as sustainable corrosion inhibitor for mild steel in aggressive corrosive media.

This study investigates the corrosion inhibition potential of Polygonum cuspidatum root extract (PCRE) on mild steel in a 0.5 M HCl acidic environment. Herein, various techniques including electrochemical and gravimetric measurements were employed, along with scanning electron microscopy (SEM) and contact angle (CA) measurements for surface morphology analysis. The impedance study revealed a concentration-dependent enhancement in corrosion resistance, classifying PCRE as a mixed-type inhibitor (i.e., inhibits both anodic and cathodic reactions). The highest efficiency, 96.71% at 298 K, was observed at a 1000-ppm PCRE concentration. Langmuir model computations suggested chemisorption and physisorption of PCRE on the electrode substrate. Increased Rp (from 28.648 to 174.01 Ω) and Rct (185.74 Ω cm2) at 1000 ppm demonstrated improved corrosion resistance. Additionally, SEM analysis displayed a uniform, protective surface, reducing metal degradation. Theoretical calculations highlighted strong interactions between PCRE and mild steel, with a low energy gap (ΔE), as follows: 1-O-methylemodin (2.267 eV) < emodin (2.288 eV) < emodin-1-O-glucoside (2.343 eV) < piceid (2.931 eV) < resveratrol (2.952 eV), confirming PCRE's excellent micro-level anti-corrosion capabilities. This eco-benign corrosion inhibitor offers sustainable, low-toxicity protection, cost-effectiveness, and versatile performance, surpassing commercial counterparts while aligning with sustainability goals.

Integrating experimental and theoretical studies in the development of a novel alginate-based bio-composite for copper anticorrosion in 3.5 % NaCl environments.

The development of new coatings based on a biopolymer, epichlorohydrin-modified alginate, and alginate-epichlorohydrin-SrTiO3 nanocomposites incorporating SrTiO3 (STO) nanoparticles in the alginate (Alg) matrix (Alg-Ep-STO), has been addressed in this study. Various characterization techniques were employed to analyze the prepared compounds, including X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), as well as surface analysis methods such as Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). Furthermore, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarisation (PDP) methods were used to evaluate corrosion inhibition and protection durability. The results demonstrate that the incorporation of STO nanoparticles into the alginate matrix with epichlorohydrin significantly improved the metal's resistance to corrosion. The experimental findings received reinforcement from various computational methods, including density functional theory (DFT), Molecular Dynamics (MD) and Monte Carlo (MC) simulations, which were employed to investigate the interactions between the Alg-Ep-STO nanocomposite and the copper surface. The computational outcomes revealed that the Alg-Ep-STO nanocomposite exhibits robust adhesion to the copper surface, maintaining a flat orientation, with its alignment being notably influenced by the presence of STO nanoparticles.

Hybrid epoxy/Br inhibitor in corrosion protection of steel: experimental and theoretical investigations.

The corrosion of carbon steel infrastructure in acidic environments poses significant economic and safety challenges. Traditional inhibitors such as chromates are being phased out due to toxicity concerns. Thus, there is a need to develop effective and sustainable green alternatives. In this work, we evaluated an epoxy-based inhibitor, bisphenol A tetrabromo dipropoxy dianiline tetraglycidyl ether (TGEDADPTBBA), for protecting carbon steel against corrosion in 1 M hydrochloric acid. An integrated experiment-computation approach was employed. Polarization curves and electrochemical impedance spectroscopy were used to assess the inhibition efficiency and mechanism of TGEDADPTBBA. Quantum chemical calculations and molecular dynamics simulations provided atomic-level insights into adsorption behavior. Scanning electron microscopy with energy-dispersive X-ray spectroscopy characterized the surface morphology. The results showed that TGEDADPTBBA acted as a highly effective mixed-type inhibitor, achieving over 95% inhibition efficiency at a 10-3 M concentration. It suppressed corrosion currents while increasing the charge transfer resistance. Theoretical studies revealed that TGEDADPTBBA adsorbed onto steel surfaces via both electrostatic and van der Waals interactions. This stable adsorption facilitated the formation of a protective barrier layer, as observed experimentally. Notably, our work demonstrated the synergistic potential of combining experimental corrosion testing with computational modeling to develop structure-property relationships for innovative inhibitor design. This integrated approach offers insight into inhibition mechanisms and presents TGEDADPTBBA as an attractive green corrosion inhibitor alternative for industrial applications.

Experimental and computational studies on the corrosion inhibition potential of a novel synthesized thiophene and pyridine-based 1,3,4-oxadiazole hybrid against mild steel corrosion in 1 N HCl.

A convenient synthesis of a novel 1,3,4-oxadiazole derivative, specifically known as, 2-(5-methylthiophen-2-yl)-5-(pyridin-3-yl)-1,3,4-oxadiazole (MTPO), is reported along with a comprehensive evaluation of its ability to inhibit the corrosion of mild steel (MS) in a 1 N HCl environment using weight loss, EIS, PDP, SEM, EDX, and UV-Vis spectroscopy. The investigated inhibitor expressed excellent inhibition efficiency (99.05% at 500 ppm, 298 K) with a mixed-type inhibitory mechanism as demonstrated by the PDP technique. Furthermore, MTPO followed Langmuir adsorption isotherm, which provides insights into the adsorption phenomena, demonstrating that it exhibits superior adsorption behavior on the MS surface compared. In silico investigations, using DFT computation and MD simulation complements the experimental outcomes revealing strong adsorbing attributes of the MTPO hybrid with the ω - and ω + values of 8.8882 eV and 4.4787 eV, respectively. In addition, the radial distribution function also addressed the chemisorption behavior of MTPO. This article also takes into consideration the various ways in which the inhibitor interacts with the mild steel, offering potential insights for developing strategies to mitigate metal dissolution in acidic environments.

Adsorption of Methylene Blue Dye and Analysis of Two Clays: A Study of Kinetics, Thermodynamics, and Modeling with DFT, MD, and MC Simulations.

The purpose of this research was to learn more about the primary and secondary properties of Moroccan natural clay in an effort to better investigate innovative adsorbents and gain access to an ideal adsorption system. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis (SEM-EDX) and X-ray fluorescence were employed for identification. SEM revealed clay grains, including tiny particles and unevenly shaped sticks. First- and second-order rate laws, representing two distinct kinetic models, were applied in the kinetic approach. Adsorption of dye MB onto natural clay was studied, and the results agreed with the 2 s order model. The significant correlation coefficients support the inference that the adsorption process was governed by the Langmuir model. Subsequent DFT analyses demonstrated that the methylene blue dye's HOMO and LUMO surfaces are dispersed across most of the dye's components, pointing to a strong interaction with the clay. To determine how the dye might be adsorbed onto the clay, we employed quantum descriptors to locate its most nucleophilic and electrophilic centers. Endothermic reactions are evident during the MB adsorption process on clay, as indicated by the positive values of ΔH0 and ΔS0 (70.49 kJ mol-1of RC and 84.19 kJ mol-1 of OC and 10.45 J mol-1 K-1 of RC and 12.68 mol-1 K-1 of OC, respectively). Additionally dye molecules on the adsorbent exhibit a higher order of distribution than in the solution, indicating that the adsorption process is spontaneous.

Unraveling the electronic influence and nature of covalent bonding of aryl and alkyl radicals on the B12N12 nanocage cluster.

Carbon nanocage structures such as fullerene, nanotubes, nanocapsules, nanopolyhedra, cones, cubes, and onions have been reported since the discovery of C60, and they offer tremendous promise for investigating materials of low dimensions in an isolated environment. Boron Nitride (BN) nanomaterials such a: nanotubes, nanocapsules, nanoparticles, and clusters have been described in several studies and are predicted to be useful as electronic devices, high heat-resistance semiconductors, nanocables, insulator lubricants, and gas storage materials. The interaction, and electronic of octahedral B12N12 nanocage cluster covalently modified from the attachment of alkyl and aryl radicals were analyzed using Density Functional Theory calculations. The work discusses for the first time to our knowledge the complete investigation of the impact of the grafted aryl and alkyl groups on the electronic, bang gap, and density of states on the B12N12. Furthermore, this is the first complete description of these radicals attaching to a surface of B12N12 nanocage cluster.

A Combined Experimental and Computational (DFT, RDF, MC and MD) Investigation of Epoxy Resin as a Potential Corrosion Inhibitor for Mild Steel in a 0.5 M H2SO4 Environment.

In this work, a tetrafunctional epoxy resin entitled 2,3,4,5-tetraglycidyloxy pentanal (TGP) was tested and investigated as a potential corrosion inhibitor for mild steel (MS) in 0.5 M H2SO4 solution. The corrosion inhibition process for mild steel was employed alongside various techniques, such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), temperature effect (TE), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and theoretical approaches (DFT, MC, RDF and MD). Further, the corrosion efficacies obtained at the optimum concentration (10-3 M of the TGP) were 85.5% (EIS) and 88.6% (PDP), respectively. The PDP results indicated that the TGP tetrafunctional epoxy resin acted the same as an anodic inhibitor type in 0.5 M H2SO4 solution. SEM and EDS analyses found that the protective layer formed on the MS electrode surface in the presence of TGP could prevent the attack of the sulfur ions. The DFT calculation provided more information regarding the reactivity, geometric properties and the active centers of the corrosion inhibitory efficiency of the tested epoxy resin. RDF, MC and MD simulations showed that the investigated inhibitory resin have a maximum inhibition efficiency in 0.5 M H2SO4 solution.

Electrochemical, surface morphological and computational evaluation on carbohydrazide Schiff bases as corrosion inhibitor for mild steel in acidic medium.

Anticorrosion and adsorption behaviour of synthesized carbohydrazide Schiff bases, namely (Z)-N'-(4-hydroxy-3-methoxybenzylidene)-6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carbohydrazide(MBTC) and (Z)-N'-(3,4-dichlorobenzylidene)-6-methyl-2-oxo-4-phenyl-1,2,3,4-tetrahydropyrimidine-5-carbohydrazide (CBTC) was examined for mild steel (MS) in 15% HCl medium. The corrosion inhibition study was performed by using gravimetric, thermodynamic, electrochemical and theoretical studies including density functional theory (DFT), molecular dynamic simulation (MDS) and Monte Carlo simulations (MCS). The outcomes in terms of corrosion inhibition efficiency using electrochemical impedance spectroscopy (EIS) method at 303 K and 150 ppm concentration were 96.75% for MBTC and 95.14% for CBTC. Both inhibitors adsorbed on the MS surface through physical as well as chemical adsorption and followed the Langmuir isotherm. The mixed-type nature of both inhibitors was identified by polarization results. Surface analysis was done using FESEM, EDX, AFM and XPS studies and results showed that a protective layer of inhibitor molecules was developed over the surface of MS. The results of DFT, MCS and MDS are in accordance with experimental results obtained by weight loss and electrochemical methods.

Cellulose based polyurethane with amino acid functionality: Design, synthesis, computational study and application in wastewater purification.

Contamination in water is due to various environmental pollutants from natural and anthropogen activities. To remove toxic metals from contaminated water, we developed a novel adsorbent in foam form based on an olive industry waste material. The foam synthesis involved oxidation of cellulose extracted from the waste to dialdehyde, functionalization of the cellulose dialdehyde with an amino acid group, reacting the functionalized cellulose with hexamethylene diisocyanate and p-phenylene diisocyanate to produce the target polyurethanes Cell-F-HMDIC and Cell-F-PDIC, respectively. The optimum condition for lead(II) adsorption by Cell-F-HMDIC and Cell-F-PDIC were determined. The foams show the ability to quantitatively remove most of metal ions present in a real sample of sewage. The kinetic and thermodynamic studies confirmed a spontaneous metal ion binding to the foams with a second pseudo-order adsorption rate. The adsorption study revealed it obeys the Langmuir isotherm model. The experimental Qe values of both foams Cell-F-PDIC and Cell-F-HMDIC were 2.1929 and 2.0345 mg/g, respectively. Monte Carlo (MC) and Dynamic (MD) and simulations showed excellent affinity of both foams for lead ions with high adsorption negative energy value indicating vigorous interactions of Pb(II) with the adsorbent surface. The results indicate the usefulness of the developed foam in commercial applications. ENVIRONMENTAL IMPLICATION: Elimination of metal ions from contaminated environments is important for a number of reasons. They are toxic to humans via interaction with biomolecules, resulting in disruption of the metabolism and biological activities of many proteins. They are toxic to plants. Industrial effluents and/or wastewater discharged from production processes, contain a considerable amount of metal ions. In this work, the use of naturally produced materials, such as olive waste biomass, as adsorbents for environmental remediation has received great attention. This biomass represents unused resources and presents serious disposal problems. We demonstrated that such materials are capable of selectively adsorbing metal ions.

Physicochemical Characterization of Clay and Study of Cationic Methylene Blue Dye Adsorption.

In an attempt to examine novel adsorbents in accessing an ideal adsorption system, this study aimed to help understand the main and secondary characteristics of a Moroccan natural clay. X-ray fluorescence, infrared, and scanning electron microscopy with energy-dispersive X-ray spectroscopy analysis (SEM-EDX) were used for the identification. The findings demonstrate that this Clay is composed of a mixture of quartz, calcite, magnetite, and Rutile in very high proportions. SEM revealed the presence of clay grains in the presence of fine particles and irregularly contoured sticks. The results of semiquantitative detection by EDX also reveal the presence of certain mineral species (Si, Al, Mg, Fe, K, Cl, S, Ca, and Na). The exploited kinetic technique was achieved using two different kinetic models: first- and second-order rate laws. Commensurate to the obtained results, the 2-sec order model better described the adsorption of dye MB onto the natural clay. The results confirmed that the adsorption process followed the Langmuir model with the high coefficient correlation obtained which are very close to 1. In the sequel, DFT results revealed that the HOMO and LUMO surfaces of the methylene blue dye are mostly distributed on all dye parts, reflecting possible strong interactions with the clay. The quantum descriptors investigated in this study identify the most nucleophilic and electrophilic centers that can be used to suggest a suitable mechanism for the adsorption of the dye by the clay. The values of enthalpy ΔH0 and entropy ΔS0 of activation were -15.88 kJ mol-1 and -0.021 J mol-1 K-1, respectively, show that the nature of the adsorption process of MB on clay is exothermic and the order of distribution of the dye molecules on the adsorbent increases with respect to that of the solution so the negative values of ΔG0 (from -9. 62 to -8.99 kJ mol-1) indicate that the adsorption process is spontaneous.

Application of Taguchi method, response surface methodology, DFT calculation and molecular dynamics simulation into the removal of orange G and crystal violet by treated biomass.

In this work, the efficiency of the treated plant Carpobrotus edulis (TPCE) as an effective biosorbent for removing the orange G (OG) and crystal violet (CV) dyes from aqueous solution was investigated. TPCE was characterized by FT-IR, Ss, pHz and SEM-EDX. The influence of parameters such as bioadsorbent dose, contact time, initial concentration, temperature and pH was tested using Taguchi experimental design (TED) with L8 orthogonal array (five parameters in two levels). The initial concentration, bioadsorbent dose and contact time are the main parameters for the removal of CV and OG dyes, while the effects of pH and temperature are minimal. The maximum removal efficiency of dyes under optimal operating conditions was 97.93 % and 92.68 %, respectively. which at the optimal conditions of 3 g/L, pH 10, 20 mg/L, 35 °C, 5 min and 15 g/L, pH 4, 20 mg/L, 35 °C, 60 min for CV and OG dyes, respectively. The results of response surface methodology (RSM) and analysis of variance (ANOVA) showed that the initial concentration Ci of CV dye was the most significant factor in the adsorption efficiency with a contribution of 51.56 %. On the other hand, the OG bioadsorbent dose is the most important factor in adsorption efficiency with a percentage contribution of 56.41 %. The Density Functional Tight Binding (DFTB) method shows that dyes strongly bind the adsorbent surface. Monte Carlo and molecular dynamics simulations show significant interactions between dye and adsorbent surface. The reusability of biomaterial indicated that the adsorption performance dropped very slightly up to five cycles.