Chemisorption Mechanism Research Articles

Molecular sieve 13X activated zeolite for CO2 filter in air purifier

Indoor air quality is crucial for health. Room with high CO2 concentration can cause sick building syndrome such as dizziness, nausea, fatigue, and breathing difficulties. In addition to the air circulation, air filtering can reduce CO2 and improve the indoor air quality. The integration of activated zeolite into conventional air cleaning filters, which lack specific CO2 gas selectivity, presents a promising solution for CO2 reduction. Possessing cage-like porous structures and extra framework cations, activated zeolites have been known as gas adsorbers via physisorption and chemisorption mechanism. Activated zeolites have been reported to have high selectivity to CO2 gas via electrostatic interaction and trapping in small pores. In this study, we integrated the molecular sieve13X activated zeolite (MSAZ) with typical pore size around 1 nm to the conventional filters in air purifier which does not have specific selectivity to CO2 gas. By varying the MSAZ masses, we demonstrated that the MSAZ addition effectively reduce around 147 up to 316 ppm CO2 depending on the MSAZ mass and the air purifier fan speed. This value is extremely higher compared to 4 ppm CO2 reduction by commercial carbon filter without MSAZ. Larger mass and faster fan speed resulted in higher CO2 reduction. This study proves the prospective application of the MSAZ for CO2 reduction, to improve the indoor air quality and to avoid adverse effects of CO2 exposure.

Sono-assisted adsorption of nitrate by Fe-modified chitosan–zeolite composite material

The negative consequences of nitrate pollution on the environment and human health, that gained substantial attention. The purpose of this work is to formulate and evaluate the potential of the Fe-modified chitosan–zeolite composite (CZFC) as an efficient adsorbent for the removal of nitrate. Physical and chemical characterization techniques such as SEM, XRD, and FTIR were used to analyze the surface and structural properties of the CZFC. The effects of several variables, including the pH, contact time, initial concentration, and adsorbent dosage, were investigated under ultrasonication treatment throughout experiments. When compared to the Freundlich and Temkin models, the Langmuir models had the highest R 2 value (0.99), indicating that they had the best fitting for all the experimental data. The maximum adsorption capacity was found to be 5.18 ± 0.30 mg g−1 with 95.37 ± 2.11% of nitrate removal at pH 3 and 2 g L−1 of adsorbent dose. The pseudo-second-order model exhibited the highest R 2 value (0.99) and proved the chemisorption mechanism for nitrate removal. The thermodynamic properties indicated that the adsorption was spontaneous and exothermic. The regeneration capacity of the CZFC was found to be 80.86 ± 4.17% at pH 10 due to the weakening of electrostatic attraction. According to experimental results, ultrasonication treatment was crucial for increasing nitrate absorption on synthesized CZFC.

Effective removal of Congo red from aqueous solutions using ethylenediamine-modified wheat straw as adsorbent

In this study, ethylenediamine (EDA)-modified wheat straw (EMWS) was prepared and used as an efficient adsorbent for removing Congo red (CR) from aqueous solutions. Adsorption of CR by EMWS was examined through static adsorption experiments to determine the effect of contact time, initial pH values, particle size of the adsorbent, solution concentration, and temperature. As pH ranged from 4.0 to 10.0, CR adsorption by the EMWS remained considerably elevated. The equilibrium adsorption capacity was determined to be 97.92 mg·g−1 for a CR concentration of 400 mg·L−1, pH of 4.0, temperature of 318 K, and EMWS dose of 2 g·L−1, which was found to be comparable to other materials used for CR adsorption. Following that, optimal conditions were used to conduct isothermal, kinetic, and thermodynamic studies. In the adsorption process of CR, the Freundlich isotherm model and the pseudo-second-order (PSO) kinetics provided the best fit, indicating the presence of both physisorption and chemisorption mechanisms. Electrostatic attraction and hydrogen bonding were primarily responsible for CR adsorption onto the EMWS. Based on thermodynamic investigations, the adsorption of CR on EMWS is determined to be spontaneous (ΔG < 0) and endothermic (ΔH = 60.83 kJ·mol−1), while also exhibiting an increase in disorder (ΔS = 289.9 J·mol−1·K−1). The elution was carried out using 0.20 M HCl, followed by washing the EMWS with water, resulting in no loss of functionality. This study suggests that EMWS possesses the potential to serve as a feasible and efficient adsorbent for CR removal in wastewater.

High-Capacity, Cooperative CO2 Capture in a Diamine-Appended Metal-Organic Framework through a Combined Chemisorptive and Physisorptive Mechanism.

Diamine-appended Mg2(dobpdc) (dobpdc4- = 4,4'-dioxidobiphenyl-3,3'-dicarboxylate) metal-organic frameworks are promising candidates for carbon capture that exhibit exceptional selectivities and high capacities for CO2. To date, CO2 uptake in these materials has been shown to occur predominantly via a chemisorption mechanism involving CO2 insertion at the amine-appended metal sites, a mechanism that limits the capacity of the material to ∼1 equiv of CO2 per diamine. Herein, we report a new framework, pip2-Mg2(dobpdc) (pip2 = 1-(2-aminoethyl)piperidine), that exhibits two-step CO2 uptake and achieves an unusually high CO2 capacity approaching 1.5 CO2 per diamine at saturation. Analysis of variable-pressure CO2 uptake in the material using solid-state nuclear magnetic resonance (NMR) spectroscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) reveals that pip2-Mg2(dobpdc) captures CO2 via an unprecedented mechanism involving the initial insertion of CO2 to form ammonium carbamate chains at half of the sites in the material, followed by tandem cooperative chemisorption and physisorption. Powder X-ray diffraction analysis, supported by van der Waals-corrected density functional theory, reveals that physisorbed CO2 occupies a pocket formed by adjacent ammonium carbamate chains and the linker. Based on breakthrough and extended cycling experiments, pip2-Mg2(dobpdc) exhibits exceptional performance for CO2 capture under conditions relevant to the separation of CO2 from landfill gas. More broadly, these results highlight new opportunities for the fundamental design of diamine-Mg2(dobpdc) materials with even higher capacities than those predicted based on CO2 chemisorption alone.

Inhibitive Action of Sulfide Ions on Corrosion and Enhancing Charge‐Discharge Efficiency of Zinc and Zinc‐Indium Alloy as Anode for Alkaline Batteries

AbstractThe obtained data reveal that the coverage of surface (θ) and protection efficiency (η%) for the studied electrodes increases gradually as the inhibitor concentration increases. Tafel plot is carried out at variant temperatures in the investigated basic electrolyte containing 1×10−1 M of S ions. This study reveals that the activation energy barrier of the studied alloy is higher than that of pristine zinc anode at a fixed inhibitor concentration. It is observed that ▵Goads. and η% values rise with rising solution temperature, indicating that S ions adsorption on the studied electrode surfaces occurs by a chemisorption mechanism. Other calculations are made for the additional thermodynamic parameters such as ▵Hoadsand ▵Soads. The zinc anodes get more efficient when S ions are added to the solution, considerably decreasing electrochemical polarization. In addition, the presence of indium sulfide improves the exposed surface area of the alloy, supplying additional improvement in charge‐discharge efficiency. Density functional theory (DFT) is utilized to extract the quantum data to acquire a deeper understanding of the chemical processes between sulfide ions at the interface.

Removal of tetracycline by natural and iron-modified orange peel from aqueous solutions: processes in batch, column, and mechanism

ABSTRACT Natural (OP) and iron modified orange peel (Fe-OP) were used for the removal of tetracycline from aqueous solutions in batch and fixed bed column systems. The adsorbents were characterized by infrared spectroscopy (IR) and the morphologies of the surfaces before and after tetracycline removal were determined by scanning electron microscope and the elemental analysis was performed by X-ray dispersive spectroscopy (EDS). The kinetic behaviour showed that the equilibrium was reached in 24 and 10 h for OP and Fe-OP respectively, the data were adjusted to both the pseudo second order and intraparticle diffusion models which indicate a chemisorption mechanism and the adsorption process is controlled by the intraparticle diffusion process. The isotherms showed that the adsorption capacity was eight times higher for Fe-OP than OP and the data were best fitted to the Freundlich model indicating that the materials are heterogeneous. The effect of flow rate, influent concentration and adsorbent mass were determined in the column system. The data were adjusted to the Thomas, Adams–Bohart and Yoon-Nelson models, and the best adjustment of data was with the first one. The adsorption capacities in the column system were about half of those obtained in the batch system. These adsorbents show good properties for the removal of tetracycline from water.

Utilization of water hyacinth (Eichhornia crassipes) biomass as eco-friendly sorbent for petroleum oil spill cleanup

Abstract This study focuses on the removal of spent engine oil (SEO) spill from the water surface using water hyacinth biomass (WHB)-based sorbents. The raw WHB was modified using extra virgin coconut oil (mainly consisting of lauric acid) to enhance the hydrophobicity and floating ability. With varying amounts of coconut oil and solvent, six diverse types of modified water hyacinth biomass (MWHB) were prepared. Among these MWHBs, an equal proportion of coconut oil and raw WHB with 10% methanol solution exhibited the highest removal of SEO reaching 96%. Various sorption kinetics and isotherm models were examined to understand the SEO sorption process on MWHB. The pseudo-second-order kinetics (R2 0.999) and both the Langmuir and Freundlich isotherm models (R2 0.992 and R2 0.999, respectively) were found to be the best-fitting models. These findings indicated a chemisorption mechanism involving the initial monolayer coverage of SEO molecules on the MWHB surface followed by the development of multilayers. The MWHB achieved a maximum sorption capacity of 4.75 g/g within 60 min. Furthermore, the reusability tests showed that MWHB maintained a sorption capacity of over 90% even after the third sorption–desorption cycle.

Synthesis, characterization, and corrosion protection potential of a highly effective and water‐miscible surfactant for mild steel in sulfuric acid solution

AbstractIn the current study, a tetracationic quaternary ammonium salt (TCQAC) was synthesized and characterized and its ability to suppress corrosion on mild steel (MS) in a 0.5 M H2SO4 solution was examined. Various chemical, electrochemical, and surface characterization techniques were utilized to study the inhibition efficiency of TCQAC. The TCQAC manifests 99.83% efficiency at 20 ppm concentration. Out of all the examined isotherm models, the Langmuir isotherm offered the best fit for the TCQAC adsorption on the MS surface. A very high negative value of ΔGads (−45.18 kJ mol−1) suggests that the adsorption of TCQAC followed the chemisorption mechanism. Electrochemical studies indicate that TCQAC increases the linear and charge transfer resistances (LPR and Rct, respectively). TCQAC slows down the anodic and cathodic Tafel reactions; however, it acts as an anodic‐type inhibitor at 5, 10, and 20 ppm. The appearance of extra Cl and N signals in the energy dispersive x‐ray (EDX) spectrum and an improvement in surface smoothness in the scanning electron microscope (SEM) image of the inhibited sample corroborated the adsorption method of corrosion inhibition. X‐ray photoelectron spectroscopy (XPS) study indicates that TCQAC creates corrosion preventive layers by chemical adsorption. In Frontier molecular orbitals (FMOs), highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were delocalized around the central part that comprises two benzyls, four allyls, and one hydrocarbon ((CH2)6) moieties and two quaternary nitrogen atoms. The outcomes of XPS and density functional theory (DFT) analyses indicate that the chemisorption of TCQAC occurs by dπ–pπ bonding with the surface iron atoms. The π‐electrons of aryl and allyl moieties extensively participate in the bonding.

Synthesis, characterization and application of Zeolite/Bi2O3 nanocomposite in removal of Rhodamine B dye from wastewater

Many factories use a variety of colours to enhance product aesthetics, leading to untreated wastewater being discharged into natural water bodies. This wastewater not only poses a threat to aquatic life but also endangers human health, causing issues like skin diseases, as some dyes are carcinogenic. Rhodamine B dye (RhB) is commonly used in industries such as textiles, paper, etc. This study focuses on synthesizing, characterizing, and applying Zeolite/Bi2O3 nanocomposites to efficiently remove RhB dye. Nanocomposites were synthesized using the sol-gel method and characterized using techniques including FTIR, SEM-EDS, XRD, DLS, point of zero charge determination, and surface resonance analysis. The removal process in an aqueous solution achieved its maximum efficiency of 100% under the following optimal conditions: initial concentration of RhB dye (0.5 mg/L), time (10 min), adsorbent dose (0.55 g), pH (4), and temperature (298 K). Real wastewater testing confirmed the nanocomposite's efficiency, removing a significant 98.12% of RhB dye. Reusability tests showed stability, with removal efficiencies of 100%, 97.08%, and 88.9% over three cycles. Isotherm analysis adhered to the Freundlich Isotherm Model (R2 = 0.9953), signifying favourable adsorption behaviour. Kinetic analysis supported the pseudo-second-order model, indicating a chemisorption mechanism. Thermodynamic analysis suggested spontaneous (negative ΔG°) and endothermic (positive ΔH°) adsorption, with reduced randomness (negative ΔS°) at the solid-liquid interface. In conclusion, wastewater dye removal, especially Rhodamine B, is vital for environmental and public health protection. The Zeolite/Bi2O3 nanocomposite emerges as an efficient, sustainable, and eco-friendly adsorbent for Rhodamine B dye removal in both synthetic solutions and real wastewater.

Ultrasound assisted removal of methylene blue using functionalized mesoporous biochar composites

Global wastewater pollution issues demands developing innovative and cost-efficient techniques for wastewater treatment. The current study reports application of different metal oxide (iron, copper, zinc) doped carbon-based materials such as activated carbon (AC), groundnut shell (GS), cotton stalk (CS) and biochar (BC) for the removal of methylene blue (MB). Iron oxide-doped AC exhibited significantly higher adsorption capacity (∼32 mg/g) with all the other metal oxide-doped AC having the adsorption capacity below ∼10 mg/g. Adsorption of MB on FeCS followed the Freundlich isotherm, suggesting multilayer adsorption on the heterogeneous active sites. Kinetic models indicated dominant chemisorption mechanisms, aligning well with the pseudo-second-order model. Higher adsorption capacity under alkaline pH conditions is attributed to the prevalence of negative charges on the surface. The presence of ultrasound further intensified the adsorption behavior resulting in a maximum removal efficiency of ∼90 % within 10 min. An optimum adsorbent loading of 0.5 g/L was determined for effective removal of MB. FeCS adsorbent displayed stable performance over multiple cycles, affirming its reliability for reuse. These results shed light on the practical application of biochars derived from large scale pyrolysis process for the wastewater remediation.

Synthesis of Aminomethylpyridine-Decorated Polyamidoamine Dendrimer/Apple Residue for the Efficient Capture of Cd(II).

Water contamination irritated by Cd(II) brings about severe damage to the ecosystem and to human health. The decontamination of Cd(II) by the adsorption method is a promising technology. Here, we construct aminomethylpyridine-functionalized polyamidoamine (PAMAM) dendrimer/apple residue biosorbents (AP-G1.0-AMP and AP-G2.0-AMP) for adsorbing Cd(II) from aqueous solution. The adsorption behaviors of the biosorbents for Cd(II) were comprehensively evaluated. The maximum adsorption capacities of AP-G1.0-AMP and AP-G2.0-AMP for Cd(II) are 1.40 and 1.44 mmol·g-1 at pH 6. The adsorption process for Cd(II) is swift and can reach equilibrium after 120 min. The film diffusion process dominates the adsorption kinetics, and a pseudo-second-order model is appropriate to depict this process. The uptake of Cd(II) can be promoted by increasing concentration and temperature. The adsorption isotherm follows the Langmuir model with a chemisorption mechanism. The biosorbents also display satisfied adsorption for Cd(II) in real aqueous media. The adsorption mechanism indicates that C-N, N═C, C-O, CONH, N-H, and O-H groups participate in the adsorption for Cd(II). The biosorbents display a good regeneration property and can be reused with practical value. The as-prepared biosorbents show great potential for removing Cd(II) from water solutions with remarkable significance.

Process Optimization and Equilibrium, Thermodynamic, and Kinetic Modeling of Toxic Congo Red Dye Adsorption from Aqueous Solutions Using a Copper Ferrite Nanocomposite Adsorbent.

In the present investigation of copper ferrite, a CuFe2O4 nanocomposite adsorbent was synthesized using the sol-gel method, and its relevance in the adsorptive elimination of the toxic Congo red (CR) aqueous phase was examined. A variety of structural methods were used to analyze the CuFe2O4 nanocomposite; the as-synthesized nanocomposite had agglomerated clusters with a porous, irregular, rough surface that could be seen using FE-SEM, and it also contained carbon (23.47%), oxygen (44.31%), copper (10.21%), and iron (22.01%) in its elemental composition by weight. Experiments were designed to achieve the most optimized system through the utilization of a central composite design (CCD). The highest uptake of CR dye at equilibrium occurred when the initial pH value was 5.5, the adsorbate concentration was 125 mg/L, and the adsorbent dosage was 3.5 g/L. Kinetic studies were conducted, and they showed that the adsorption process followed a pseudo-second-order (PSO) model (regression coefficient, R2 = 0.9998), suggesting a chemisorption mechanism, and the overall reaction rate was governed by both the film and pore diffusion of adsorbate molecules. The process through which dye molecules were taken up onto the particle surface revealed interactions involving electrostatic forces, hydrogen bonding, and pore filling. According to isotherm studies, the equilibrium data exhibited strong agreement with the Langmuir model (R2 = 0.9989), demonstrating a maximum monolayer adsorption capacity (qmax) of 64.72 mg/g at pH 6 and 302 K. Considering the obtained negative ΔG and positive ΔHads and ΔSads values across all tested temperatures in the thermodynamic investigations, it was confirmed that the adsorption process was characterized as endothermic, spontaneous, and feasible, with an increased level of randomness. The CuFe2O4 adsorbent developed in this study is anticipated to find extensive application in effluent treatment, owing to its excellent reusability and remarkable capability to effectively remove CR in comparison to other adsorbents.

Direct CO2 capture from simulated and Ambient Air over aminosilane-modified hierarchical silica

Aminosilane-modified Hierarchical silica, HSA and HST-based adsorbents were synthesized by aminosilanization using Hierarchical silica (HS) with 3-aminopropyltriethoxysilane (APS) and N1-(3-trimethoxysilylpropyl)diethylenetriamine (TMPTA), respectively, and characterized to establish their physicochemical, structural, morphological, and porosity properties. Their CO2 adsorption performance was evaluated under direct air capture (DAC) conditions: 1) simulated air with CO2 concentration of 400 ppm in helium (He) at 30 °C and 2) indoor air with CO2 concentration ≥400 ppm at 30 °C, where HSA and HST modified with 70 wt% of respective aminosilanes outperformed others. The modified HS adsorbents showed an increase in kinetics, CO2 uptake under dry and humid conditions, stable cyclic adsorption-desorption performance, moderate enthalpy of desorption indicating a dominant chemisorption mechanism. Under dry and humid simulated air conditions (400 ppm CO2 in He), HSA-70 displayed a CO2 uptake of 0.82 mmol/g and 1.70 mmol/g, respectively, while HST-70 exhibited enhanced CO2 uptake of 1.54 mmol/g and 2.08 mmol/g, respectively. Cyclic stability of HSA-70 and HST-70 was confirmed through five thermal swing adsorption (TSA) cycles. In addition to this, their use for indoor air CO2 capture was also explored through ten short TSA cycles. Developed HSA-70 and HST-70 adsorbents exhibited more selectivity for CO2 over water, demonstrating their usage in practical direct air CO2 capture application.

TiO2 modified para-aramid nanofiber composite separator for thermal runaway prevention and shuttle effect mitigation of lithium-sulfur batteries

The polyolefin separators commonly used in lithium-sulfur (Li-S) batteries are not able to withstand high temperatures and easily lead to thermal runaway and cause safety problems. In addition, the pore size of the polyolefin separator is too large to inhibit the shuttle effect of polysulfide. Herein, TiO2 modified para-aramid nanofiber (TiO2/ANFs) composite separator for thermal runaway prevention and shuttle effect mitigation of lithium-sulfur batteries was designed and obtained. The TiO2/ANFs composite separators remained intact at 200 °C and showed excellent self-quenching characteristic. In addition, the TiO2/ANFs composite separators could inhibit the growth of lithium dendrites to a certain extent. Therefore, the TiO2/ANFs composite separators could prevent thermal runaway and had excellent safety. And TiO2 could anchor the polysulfide, which could inhibit the shuttle effect. In addition, ionic conductivity had been greatly improved due to the addition of TiO2, which was conducive to high-flux lithium-ion transfer. In particular, 2-TiO2/ANFs composite separators had an average discharge specific capacity of 889.7mAhg−1 at 0.2C. Through density functional theory (DFT) calculation, the effective chemisorption mechanism of active sulfur and TiO2 was deeply carried out. The result showed that TiO2 could ensure the effective chemisorption of active sulfur, resulting in the long-term cycling stability.

Efficient phosphate removal utilizing N, Zn-doped carbon dots as an innovative nanoadsorbent.

The primary goal of this study is to examine PO4 3- adsorption from aqueous solutions using zinc-doped carbon dots (Zn-N-CDs) as a new adsorbent and cost-effective technique. Zn-N-CDs were produced through a hydrothermal process and subsequently identified using various techniques. The effect of reaction time, temperature, pH, ionic strength, adsorbent dosage, initial PO4 3- concentration, and anion competition (NO3 -, Cl-, HCO3 -, and SO4 2-) on PO4 3- adsorption using Zn-N-CDs were investigated. The characterization results depicted that Zn-N-CDs have a spherical structure without obvious aggregation and revealed the amorphous nature of carbon dots with many pores. Zn-N-CDs had a high affinity for adsorbing PO4 3-, reaching equilibrium within 5 minutes. While PO4 3- adsorption reduced with an increase in temperature, it increased with pH and ionic strength. The optimal conditions for PO4 3- adsorption were determined to be pH 8, 100 mM KCl as an ionic strength, and 5 g L-1 of Zn-N-CDs. The presence of SO4 2- and HCO3 - as competing anions slightly decreased PO4 3- adsorption. Thermodynamic studies revealed that PO4 3- adsorption onto Zn-N-CDs was endothermic, spontaneous, and disordered, as evidenced by ΔG° < 0, ΔH° > 0, and ΔS° > 0. The experimental data fit well with a pseudo-second-order kinetic model (R 2 = 0.999) and the Freundlich isotherm model (R 2 = 0.9754), signifying that PO4 3- adsorption onto Zn-N-CDs occurs through multi-layer and chemi-sorption mechanisms. Overall, Zn-N-CDs indicated a great capability to adsorb high concentrations of PO4 3- across a wide range of pH values, indicating their potential for environmental remediation.

Nano-topography and functionalization with the synthetic peptoid GN2-Npm9 as a strategy for antibacterial and biocompatible titanium implants

In recent years, antimicrobial peptides (AMPs) have attracted great interest in scientific research, especially for biomedical applications such as drug delivery and orthopedic applications. Since they are readily degradable in the physiological environment, scientific research has recently been trying to make AMPs more stable. Peptoids are synthetic N-substituted glycine oligomers that mimic the structure of peptides. They have a structure that does not allow proteolytic degradation, which makes them more stable while maintaining microbial activity. This structure also brings many advantages to the molecule, such as greater diversity and specificity, making it more suitable for biological applications. For the first time, a synthesized peptoid (GN2-Npm9) was used to functionalize a nanometric chemically pre-treated (CT) titanium surface for bone-contact implant applications. A preliminary characterization of the functionalized surfaces was performed using the contact angle measurements and zeta potential titration curves. These preliminary analyses confirmed the presence of the peptoid and its adsorption on CT. The functionalized surface had a hydrophilic behaviour (contact angle = 30°) but the hydrophobic tryptophan-like residues were also exposed. An electrostatic interaction between the lysine residue of GN2-Npm9 and the surface allowed a chemisorption mechanism. The biological characterization of the CT_GN2-Nmp9 surfaces demonstrated the ability to prevent surface colonization and biofilm formation by the pathogens Escherichia coli and Staphylococcus epidermidis thus showing a broad-range activity. The cytocompatibility was confirmed by human mesenchymal stem cells. Finally, a bacteria-cells co-culture model was applied to demonstrate the selective bioactivity of the CT_GN2-Nmp9 surface that was able to preserve colonizing cells adhered to the device surface from bacterial infection.

Preparation of La/Mg modified sheep dung activated carbon and its adsorption characteristics for phosphorus in wastewater

The resource utilization of sheep dung from farming waste was evaluated in adsorption of total phosphorus (TP). Four types of modified sheep dung activated carbon (SDAC) were prepared: SDAC without metal (SDAC-N), SDAC with lanthanum (SDAC-La), SDAC with magnesium (SDAC-Mg), and SDAC with La and Mg (SDAC-La-Mg). The various SDACs prepared were tested in the adsorption TP from wastewater. The main components of the SDAC-La-Mg surface were MgO and La2O3. The SDAC-La-Mg surface was rich in functional groups such as CC and CO and acquired a negative charge. At 25 °C and pH of 4, the TP adsorption capacity of SDAC-La-Mg was 1.94 mg/g. Among the four SDAC adsorbents, SDAC-La-Mg exhibited the highest adsorption capacity. TP adsorption by SDAC-La-Mg followed the secondary kinetic and Langmuir isothermal adsorption models, primarily through chemisorption mechanisms such as ion exchange, chemical precipitation, and covalent bonding. SDAC-La-Mg was regenerated, and the TP removal rate remained at 65% after three regeneration cycles. Mg and La ions combine with carboxylate ions to form ligand compounds, enabling TP adsorption by displacing the -OH group on the surface of SDAC-La-Mg to form an inner complex. Thus, SDAC-La-Mg can be used as an effective adsorbent for TP in wastewater treatment.

Exploring corrosion protection for mild steel in HCl solution: An experimental and theoretical analysis of an antipyrine derivative as an anticorrosion agent

AbstractThe corrosion of mild steel in HCl solution remains a critical issue in various industrial applications. In the quest for effective corrosion inhibitors, 4‐(2‐Hydroxy‐3‐Methoxybenzylideneamino) antipyrine (HMBA) has emerged as a promising candidate. This study investigates the inhibitory properties of HMBA on mild steel corrosion in HCl solution through weight loss measurements, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) techniques. The experiments spanned over various time periods, including 1, 5, 10, 24, and 48 h. The results reveal that HMBA exhibits exceptional inhibition efficiency (IE), with an impressive 94.7% inhibition rate. This outstanding performance underscores its potential as a corrosion inhibitor for mild steel in aggressive HCl environments. To elucidate the adsorption behavior of HMBA on the mild steel surface, Langmuir isotherm modeling was employed, demonstrating a strong correlation between the experimental data and the Langmuir adsorption isotherm model. Furthermore, the study employs density functional theory (DFT) to gain insight into the mechanism of HMBA inhibition. DFT calculations suggest that both physisorption and chemisorption mechanisms are involved in the interaction between HMBA and the mild steel surface. The calculated Gibbs free energy of adsorption () is found to be approximately , indicating a spontaneous and energetically favorable adsorption process. In conclusion, HMBA emerges as a highly effective corrosion inhibitor for mild steel in HCl solution, offering impressive IE over various time intervals. The combination of experimental techniques, such as WL, EIS, and PDP, along with computational insights from DFT calculations, provides an understanding of the inhibitory properties of HMBA. These findings hold great promise for the development of environmentally friendly corrosion inhibitors in industrial applications.

NBis(2-hydroxyethyl) ammonium dodecanoate and its constituents as inhibitors for Al corrosion and H2 production in acid medium

2-(2-Hydroxyethylamino) ethanol (EA), dodecanoic acid (DA), and a freshly prepared ionic liquid named bis(2-hydroxyethyl) ammonium dodecanoate (ADD) were exercised as mitigators towards the corrosion of aluminum and the production of hydrogen in 2.0 M HCl. The study was performed by gravimetry, gasometry, potential-time measurements, and electrochemical methods. The examined concentration range of such inhibitors was varied between 5 × 10-6 M and 5 × 10-3 M. The amount of generated hydrogen is enhanced with temperature and lowered by increasing the concentration of the organic additive. Galvanostatic studies indicated that the utilized organic materials are effective inhibitors of a mixed type. The inhibition efficacy was found to increase with more additions of inhibitors and is lowered by temperature. ADD is the more effective inhibitor with a protective efficacy of 95.2% at 0.005 M and 298 K. The computed values of ΔGoads vary between – 35.48 and − 35.00 kJ/mol depending on the type of the organic compound and temperature that confirms the existence of a physical adsorption mechanism. The lowering in the Kads values with T confirms the escaping of several adsorbed organic particles from the contact metal interface. The thermodynamic adsorption functions, ΔG°ads, and Kads confirmed the spontaneous adsorption process, i.e., physical- and chemisorption mechanisms.

Innovative optimization for enhancing Pb2+ biosorption from aqueous solutions using Bacillus subtilis.

Toxic heavy metal pollution has been considered a major ecosystem pollution source. Unceasing or rare performance of Pb2+ to the surrounding environment causes damage to the kidney, nervous, and liver systems. Microbial remediation has acquired prominence in recent decades due to its high efficiency, environment-friendliness, and cost-effectiveness. The lead biosorption by Bacillus subtilis was optimized by two successive paradigms, namely, a definitive screening design (DSD) and an artificial neural network (ANN), to maximize the sorption process. Five physicochemical variables showed a significant influence (p < 0.05) on the Pb2+ biosorption with optimal levels of pH 6.1, temperature 30°C, glucose 1.5%, yeast extract 1.7%, and MgSO4.7H2O 0.2, resulting in a 96.12% removal rate. The Pb2+ biosorption mechanism using B. subtilis biomass was investigated by performing several analyses before and after Pb2+ biosorption. The maximum Pb2+ biosorption capacity of B. subtilis was 61.8 mg/g at a 0.3 g biosorbent dose, pH 6.0, temperature 30°C, and contact time 60 min. Langmuir's isotherm and pseudo-second-order model with R2 of 0.991 and 0.999 were suitable for the biosorption data, predicting a monolayer adsorption and chemisorption mechanism, respectively. The outcome of the present research seems to be a first attempt to apply intelligence paradigms in the optimization of low-cost Pb2+ biosorption using B. subtilis biomass, justifying their promising application for enhancing the removal efficiency of heavy metal ions using biosorbents from contaminated aqueous systems.