Chemisorption Process Research Articles

DFT, TD-DFT, QTAIM and NBO investigations of the interaction between sulfur mustard and metal porphyrins induced in carbon nanocone (M-PCNC, M = Fe2+ and Mg2+)

In this study, the adsorption behavior of sulfur mustard on metal porphyrins replaced in carbon nanocone (M-PCNC, M = Fe2+ and Mg2+) is explored using density functional theory (DFT) calculations. Energetics, physical parameters, and electronic properties are determined utilizing the M06-2X approach and the 6-31G(d) basis set. Based on the obtained results, the sulfur mustard exhibits strong adsorption onto the M-PCNCs, which denotes a chemisorption process between species. Furthermore, the findings suggest that the M-PCNCs are effective adsorbents in eliminating undesired sulfur mustard molecules from the surroundings. The data also show that the energy gap (or work function) of the M-PCNC structures is not affected by the adsorption of sulfur mustard, suggesting that they are unsuitable for use as sensors for the sulfur mustard in terms of electronic conductivity or work function. The UV-visible spectra of bare Fe-PCNC are also compared to its corresponding complexes, which reveals the adsorption of sulfur mustard does not alter the spectra of the Fe-PCNC and cannot act as a UV-based sensitive material for detecting sulfur mustard.

ZnS Honey‐Hump Nanocrystals: Efficient Green Catalysis for Remazol Black Dye Removal in Wastewater Treatment

AbstractThe extensive use of synthetic dyes in a variety of sectors, including textiles, leather, food, and paints are resulted in substantial environmental issues due to their persistence and toxicity in water bodies. Moreover, about twenty to forty gallons of water is used for two pounds of fabric in conventional textile industries around the globe. Hence, it is vital to develop effective and fast catalytic dye removal methods or devices. Citrullus lanatus rind is primarily researched for its effective removal of dye from aqueous solution. The ZnS nanocrystals are well known for its photocatalytic property to remove dyes. In this research, ZnS extracted from the Citrullus lanatus rind was used for investigating the removal of Remazol Black dye. The dye is said to increase heart rate and cause eye problems in humans. The ZnS is extracted using green synthesis and the work focuses on the goal of contributing to long‐term and successful water treatment solutions. The generated ZnS nanocrystals were validated using UV–vis spectroscopy, indicating the successful formation of nanoparticles. The presence of polyphenolic groups responsible for reducing metal sulfide nanoparticles was verified using FTIR spectroscopy. Transmission electron microscopy (TEM) research indicated that the produced ZnS nanocrystals had a morphology with a mean size of roughly 6 nm. The impact of nanocrystals in removing Remazol Black dye was examined, with a phenomenal clearance efficiency of 99.8% achieved in 6 min. The rapid and successful dye decomposition was attributable to the chemisorption process, demonstrating ZnS honey‐hump‐like nanocrystal potential as useful catalysts in ecological cleanup purposes.

Adsorption of Acid Yellow 36 and direct blue 86 dyes to Delonix regia biochar-sulphur

This study aims to investigate a new approach to removing hazardous dyes like Direct Blue 86 (DB86) and Acid Yellow 36 (AY36) from aqueous environments. Delonix regia biochar-sulphur (DRB-S), made from Delonix regia seed pods (DPSPs), is an inexpensive and environmentally friendly adsorbent. Different characterization investigations using BJH, BET, FTIR, SEM, DSC, TGA, and EDX were utilized in the descriptions of the DRB-S biosorbent. The optimal pH for AY36 dye and DB86 dye adsorption to the DRB-S adsorvbent was at pH 1.5. For the adsorption of AY36 and DB86 to DRB-S, equilibrium was attained at 30 and 90 min of reaction time interaction. The Langmuir model (LGM) and pseudo-second-order-model (PSOM) best describe the biosorption of both dye molecules to the biosorbent owing to the equal and homogeneous spread of the dye molecules over the biosorbent porous surface and a chemisorption process which involved the valency force through the exchange of electrons between the dye molecules and the prepared biosorbent. The determined biosorption capacities for both dyes (AY36 and DB86) were found to be 270.27 mg/g and 36.23 mg/g, respectively. In conclusion, this recently synthesised DRB-S adsorbent exhibited an impressive sorption capacity and successfully removed AY36 and DB86 dyes. This suggests that the biosorbent has potential applications in wastewater treatment and can be recycled without affecting its adsorption effectiveness.

Adsorptive removal of malachite green dye from aqueous solution using Cordia africana leaf as biosorbent

An untreated biosorbent derived from the leaves of Cordia africana was utilized in this study for the first time to remove malachite green (MG) dye from aqueous solutions via batchwise adsorption. Comprehensive characterizations of the biosorbent were conducted, including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and determination of the pH point of zero charge (pHpzc). The adsorption process was investigated under varying operational conditions: biosorbent dosage (0.25–0.65 g/100 mL), contact time (25–50 min), initial pollutant concentration (15–45 mg/L), and solution pH (4–9). Kinetic and isothermal models were employed to evaluate the adsorption mechanism. Characterization revealed an amorphous, heterogeneous surface. The biosorbent achieved an impressive MG removal efficiency of 98.9%, with a maximum Langmuir adsorption capacity (Qmax) of 6.25 mg/g, indicating a monolayer chemisorption process in agreement with Langmuir and pseudo-second-order kinetics models. This study highlights the cost-effectiveness and potential of Cordia africana leaf-based biosorbent as a sustainable and efficient solution for the decolorization of MG-laden industrial effluents, providing a pathway for practical, large-scale applications.

Nano-Fibrillated Bacterial Cellulose Nanofiber Surface Modification with EDTA for the Effective Removal of Heavy Metal Ions in Aqueous Solutions.

Nano-fibrillated bacterial cellulose (NFBC) has very long fibers (>17 μm) with diameters of approximately 20 nm. Hence, they have a very high aspect ratio and surface area. The high specific surface area of NFBC can potentially be utilized as an adsorbent. However, NFBC has no functional groups that can bind metal ions, limiting its potential applications. In this study, the hydroxyl groups on the surface of NFBC were chemically modified with EDTA monoanhydride to convert NFBC into a metal adsorbent. The fiber morphology and crystal structures of the modified NFBC were almost identical to those of the unmodified NFBC, suggesting that the surface hydroxyl groups of NFBC were well-conjugated with the EDTA groups. Surface-modified NFBC preferentially adsorbed transition metals in aqueous solutions, such as Cu(II), Hg(II), Pb(II), and Cd(II), but hardly adsorbed Mg(II) and Cr(VI). The adsorption of heavy metal ions can be explained by the pseudo-second-order kinetics of the chemisorption process and the Langmuir isotherm model. Furthermore, the EDTA-modified NFBC is a renewable and recyclable adsorbent. The results of this study indicate that surface-modified NFBC can be utilized as a biosorbent for heavy metal removal in chemical, food, pharmaceutical, and other industrial fields.

In Situ Synthesis of Zr-Doped Mesoporous Silica Based on Zr-Containing Silica Residue and Its High Adsorption Efficiency for Methylene Blue

Zr-containing silica residue (ZSR) is an industrial by-product of ZrOCl2 production obtained through an alkali fusion process using zircon sand. In this study, low-cost and efficient Zr-doped mesoporous silica adsorption materials (Zr-MCM-41 and Zr-SBA-15) were prepared in one step via the hydrothermal synthesis method using ZSR as the silicon source for the removal of methylene blue (MB) from dye-contaminated wastewater. The samples were characterized using X-ray fluorescence (XRF) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry (TG), and N2 adsorption–desorption measurements. The findings indicate that the synthesized Zr-MCM-41 and Zr-SBA-15 possess highly ordered mesoscopic structures with high specific surface areas of 910 and 846 m2/g, large pore volumes of 1.098 and 1.154 cm3/g, and average pore diameters of 4.18 and 5.35 nm, respectively. The results of the adsorption experiments show that the adsorbent has better adsorption properties under alkaline conditions. The adsorption process obeys the pseudo-quadratic kinetic model and the Freundlich adsorption isotherm model, indicating the coexistence of physical and chemisorption processes. The maximum adsorption capacities of Zr-MCM-41 and Zr-SBA-15 are 618.43 and 516.58 mg/g, respectively, as calculated by the Langmuir model (pH = 9, temperature of 25 °C). Compared with mesoporous silica prepared with sodium silicate as the silicon source, Zr-MCM-41 and Zr-SBA-15 have different structural properties and better adsorption properties due to Zr doping. These findings indicate that ZSR is the preferred silicon source for preparing mesoporous silica, and the mesoporous silica prepared using Zr silicon slag is a promising adsorbent and has great application potential in wastewater treatment.

Punica granatum peel powder and extract as green inhibitor for TMT in 1M HCl: an experimental and response surface model

ABSTRACT The construction industry widely uses TMT bars. However, its corrosion is a major challenge for civil engineers. Green corrosion inhibitors in place of inorganic inhibitors are one of the effective ways to prevent the corrosion which results sustainable solution. Researchers have not explored the corrosion mitigation of TMT bars with Punica granatum. Its peel (agro-waste) as a green inhibitor for TMT bars in powder/extract form exposed to 1M HCl was investigated through gravimetric and electrochemical studies using TMT bars of 8 mm diameter, 30mm, and 5 mm length respectively. The experimental work used five different concentrations of peel powder, ranging from 3.5 g to 17.5 g, and peel extract from 15 ml to 75 ml. The corrosion analysis yielded a maximum inhibition efficiency of 86.64% for powder and 83.32% for extract. Qualitative screening identified the presence of phytochemicals. The UV-Vis and FTIR spectra before and after corrosion define the chemisorption process, confirming the formation of protective layers on the bars. Steel admixed with inhibitor showed a smooth surface with fewer cracks/pits after corrosion through AFM and FE-SEM. The weight loss results were modeled using the response surface method and obtained R2 as 0.9016 (powder) and 0.9001 (extract).

Thermodynamic Studies on the Pathway and Mechanism of Coal-Oxygen-Water Coupling Reaction of Low-Temperature Oxidation

ABSTRACT It is imperative to have an in-depth understanding of the pathway and mechanism of coal-oxygen-water coupling reaction during low-temperature oxidation of coal, not only for preventing fires in the coal industry but also for reducing emissions of hazardous gases. In this study, in-situ Infrared spectroscopy characterization and quantum chemical calculations were combined to investigate in detail the chemical interactions between coal, moisture, and oxygen. In-situ infrared oxidation experiments ascertained the types and amounts of hydroxyl, aliphatic hydrocarbon, and carbonyl functional groups in lignite coal samples with varied moisture content during LTO. Subsequently, three typical molecular structures of functional groups mainly involved in the coal-oxygen reaction were chosen as the research representatives, and their reactivity was analyzed using density functional theory (DFT). Thus, the main reaction pathways of these functional groups during the LTO of coal were studied using quantum chemical methods. The results indicated that the moisture in coal significantly affected the coal–oxygen reaction by altering the chemisorption processes in the coal–oxygen combination and the active sites in coal molecules. Quantitative calculation of thermodynamic parameters such as the enthalpy and activation energy showed that moisture had a promoting effect on some reaction steps while hindering others. Moreover, the mechanism of coal-oxygen-water coupling reaction was also explored based on the reaction sequence of intermediate complexes.

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

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

Adsorption of ethylene and 1-methylcyclopropene (1-MCP) on Al-doped graphene structure: A DFT study for gas sensing application

Ethylene is the ripening hormone of fruits and vegetables. 1-Methylcyclopropene (1-MCP) is used as the inhibitor of the ethylene actions for extending the postharvest shelf life of the plants. To control the ripening and extending the shelf life of the plants, the adsorption characteristics of ethylene and 1-MCP on Al-doped graphene structure (AlG) were investigated as a gas sensing application by density functional theory (DFT) calculations. The geometric structures were optimized, HOMO and LUMO, energy gap, adsorption energies, the density of states (DOS), electrostatic potential (ESP) and the global reactivities were calculated for different distances between the adsorbed ethylene or 1-MCP and the adsorbent AlG. Chemisorption and physisorption interactions were analyzed. For the chemisorption process of ethylene and 1-MCP on AlG, the adsorption energies were 19.34 kJ/mol and 56.53 kJ/mol, respectively. Whereas for the physisorption process, the adsorption energies of ethylene and 1-MCP were -60.16 kJ/mol and -7.32 kJ/mol, respectively. As a result, it was presented that the AlG structure has sufficient characteristics to be a good adsorbent and a gas sensor of ethylene and 1-MCP.

Remediation of Ni2+ and Sr2+ ions from aqueous solutions by acacia gum/polyacrylic acid hydrogel reinforced with TiO2 nanoparticles

Abstract Globally, the environment and public health are progressively threatened due to water resource contaminants. For this purpose, a unique polyfunctional nanocomposite is created to remediate heavy metals from aqueous media. The basis of it is TiO2 composite nanoparticles (NPs) manufactured via embedding titanium oxide (TiO2) into acacia gum/acrylic acid (AG/AAc). Nanocomposite hydrogels, bearing different functional groups, are constructed employing a gamma irradiation approach that would operate as adsorbents to remove strontium (Sr2+) and nickel (Ni2+) ions from their wastes. The structure of the prepared hydrogel and its nanocomposites were confirmed by FTIR, whereas the morphology was characterized by SEM. XRD and EDX analysis confirms that the TiO2 NPs are successfully encapsulated into the prepared hydrogel. The presence of TiO2 enhances the thermal stability of the prepared hydrogel. Adsorption extent is evaluated comprehensively concerning temperature, contact time, adsorbent dosage, metal ion concentration, and pH. The physical connection between the adsorbent surface and metal ions is strengthened once TiO2 NPs are included in a copolymeric matrix, which enhances adsorption. Pseudo-second-order kinetics accurately depict the adsorption process, and the Freundlich isotherm provides the most relevant explanation of the equilibrium data. There is a demonstration that sorption is a spontaneous, feasible, and endothermic chemisorption process by examining a variety of thermodynamic parameters, including ΔH, ΔG, and ΔS.

Capability and Mechanism of Cr(VI) Removal by Phthalic Acid Modified Sulfidated Microscale Zero Valent Iron

Mechanochemically sulfidated microscale zero valent iron (S-mZVIbm) exhibits promising Cr(VI) removal performance but is prone to be passivated by Cr(VI), how to mitigate the passivation is still a challenge. In this study, we successfully synthesized phthalic acid (PA, carboxyl-rich organic acid) modified S-mZVIbm particles (PA-S-mZVIbm (4:1)) through ball milling. The pre-corrosion of the ZVI surface by PA effectively increased the specific surface area of ZVI. Additionally, the carboxyl groups complexed with Cr(VI), thereby enhancing its Cr(VI) removal capacity and alleviating the passivation. The Cr(VI) removal by PA-S-mZVIbm (4:1) was mainly a chemisorption process on the surface and its Cr(VI) removal capacity (55.47mg/g) was 1.26 and 9.94 – 14.83 times that of PA-mZVIbm and S-mZVIbm, respectively. The electron efficiency of Cr(VI) removal by both PA-S-mZVIbm (4:1) and S-mZVIbm was ~100%, however, the Fe(0) utilization efficiency of PA-S-mZVIbm (4:1) was at least 15 times higher than that of S-mZVIbm, explaining the superior performance of PA-S-mZVIbm (4:1). This study confirmed that PA modification could effectively mitigate the passivation and improve the Fe(0) utilization efficiency of S-mZVIbm.

Ecofriendly Synthesis of Nickel Oxide Nanoparticles From Fissidens Species and Its Biological Applications.

The present study was performed to synthesize eco-friendly nickel oxide nanoparticles (NiONPs) from the aqueous extract of Fissidens species (FS) and explore its biological activities. Phytochemicals, namely, alkaloids, flavonoids, sterols, tannins, proteins, carbohydrates and phenols, were present in the aqueous extract of Fissidens sp. The UV-Vis and FT-IR analyses of FS-NiONPs revealed a prominent peak at 392 nm, along with functional groups that facilitate the formation of FS-NiONPs. XRD spectrum confirmed the crystalline nature and SEM with EDX depicted the irregular, aggregated clusters and purity of FS-NiONPs. The photocatalytic activity against RB94 was achieved within 20 min with maximum decolorization efficiency (93%). The experimental data of adsorption studies fitted well with Langmuir isotherm, showcasing the monolayer adsorption of RB94 through chemisorption process. The thermodynamic study revealed that the dye removal was spontaneous, feasible and endothermic in nature. The results of antimicrobial activity and phytotoxicity study revealed the potentiality of FS-NiONPs in clinical and agricultural applications. Hence, this study emphasizes the eco-friendly synthesis of FS-NiONPs and highlights its decolorization potential, antimicrobial activity and growth promoting properties.

A novel amidoxime-functionalized covalent organic framework adsorbent for efficient lead ion removal: synthesis and adsorption mechanism

Lead ions are highly toxic heavy metal ions and Pb(Ⅱ) in wastewater threatened seriously human health and environment. Therefore, an effective adsorbent must be developed to remove lead ions from wastewater. In this study, a polycrystalline amidoxime covalent organic framework (DBCC-NHOH) is synthesized by a post-modification method for the elimination of lead (II) from wastewater. The successful preparation of adsorbent (DBCC-NHOH) is demonstrated by the oxygen appearance in SEM-EDS pattern and conversion of -CN to C=N-O and C-N in the FT-IR pattern. DBCC-NHOH is a crystalline porous material and its pore size, specific surface area and pore volume are 3.419nm, 28.154 m2/g and 4.2ⅹ10-8 m3/g respectively. The optimum conditions for the adsorption of Pb(II) by DBCC-NHOH are temperature 298K, time 180min, and pH 5. The maximum adsorption of DBCC-NHOH was 221.37mg/g. Kinetic and thermodynamic investigations indicate that adsorption of Pb(II) by DBCC-NHOH is a monolayer chemisorption and exothermic process. Selectivity experiments indicate that DBCC-NHOH can adsorb Pb(II) efficiently and selectively in complex multi-ion systems. In addition, the adsorption percentage of DBCC-NHOH remained up to 83.20% after five adsorption-desorption experiments. The XPS and FT-IR analyses and DFT results indicated that DBCC-NHOH utilized amidoxime function group to realize the high efficiency of Pb(II) adsorption by electrostatic attraction and chelation.

Activated Carbon Derived from Olive Waste for the Adsorption of Methylene Blue and Methyl Orange Dyes

AbstractVarious biomasses have been used as sustainable alternatives in the production of activated carbon for effluent treatment. This study applies Tunisian olive waste as a precursor source for the production of activated carbon (AC), through chemical activation (H3PO4). The AC was characterized through X‐ray diffraction (XRD), scanning electron microscope (SEM) and N2 adsorption desorption. The adsorption of methylene blue (MB) and methyl orange dyes (MO) onto the AC was investigated under various experimental conditions. The efficiency of removing the MB and MO increases with the addition of contact time and dosage. The optimum pH conditions for MB and MO were 7 and 2 respectively. The maximum adsorptions were achieved at 0.21 g for the two colorants. The adsorption isotherm process fits well with the Langmuir model and the maximum adsorption capacity was 34.3 and 40.5 mg g−1 for MO and MB, respectively. The adsorption kinetics data fitted well with the pseudo‐second‐order model, suggesting the chemisorption process. The obtained results reveal that AC can be used successfully to remove methyl orange and methylene blue dyes from wastewater.

Ultrasensitive and Selective Detection of Chromium(VI) Using Biowaste Derived Fluorescent Nanoprobes of Hydrothermally Synthesized Carbon‐Dots

AbstractThe Selective detection of hexavalent chromium Cr(VI), a highly toxic and carcinogenic form of chromium, at nanomolar concentration is critical due to its widespread industrial use and severe environmental and health impacts. This study presents the synthesis and application of carbon dots (CDs) derived from banana peel biowaste as a fluorescent nanosensor for the ultrasensitive and selective detection of Cr(VI). The CDs were synthesized through hydrothermal carbonization, yielding an average size of 1.9 nm, a quantum yield of 5%, and maximum fluorescence emission at 440 nm. The CDs displayed strong fluorescence quenching in Cr(VI), with minimal interference from other metal ions, highlighting their higher selectivity. CDs detection limit for Cr(VI) was determined as 52 nM or 2.7 ppb, significantly lower than those reported in recent studies, demonstrating the superior sensitivity. The quenching mechanism was further explored using X‐ray photoelectron spectroscopy (XPS), indicating that Cr(VI) undergoes reduction to Cr(III) upon interaction with the nitrogen‐containing surface functional groups of the CDs, suggesting a chemisorption process. This approach aligns with circular economy principles and supports achieving sustainable development goals (SDGs). Utilizing biowaste for synthesizing nanomaterials offers a promising pathway for creating environment friendly and cost‐effective sensors for detecting toxic metals.

Three-dimensional, multi-functionalized nanocellulose/alginate hydrogel for efficient and selective phosphate scavenging: Optimization, performance, and in-depth mechanisms.

Challenges in developing adsorbents with sufficient phosphate (P) adsorption capacity, selectivity, and regeneration properties remain to be addressed. Herein, a multi-functionalized high-capacity nanocellulose/alginate hydrogel (La-NCF/SA-PEI [La: lanthanum, NCF: nanocellulose fiber, SA: sodium alginate, PEI: polyethyleneimine]) was prepared through environmentally friendly methods. The La-NCF/SA-PEI hydrogel, featuring a 3D porous structure with interwoven functional groups (amino, quaternary ammonium, and lanthanum), demonstrated a maximum P adsorption capacity of 78.0mg/g, exceeding most La-based hydrogel adsorbents. The kinetic and isotherm fitting results confirmed the multilayer chemisorption process. Comprehensive experimental results, instrumental analysis, and computational results revealed that the ammonium phosphate complex (NH3+-O-P) and the inner-sphere complex (La-O-P) formed by La(OH)3 dominated the selective P adsorption process. Density-functional theory (DFT) was employed to calculate the bond length between phosphate and each component of the La-NCF/SA-PEI. The calculation results revealed the double-bridge adsorption between the N (apex) atom on La-NCF/SA-PEI and the O (apex) atomic site in phosphate, including electrostatic adsorption and two hydrogen bonds (bond lengths 1.001 and 1.008Å) between the O of PO43- and the H+ of the protonated amino group. Except the remarkable P adsorption performance (both municipal sewage and aquaculture tail water), the La-NCF/SA-PEI hydrogel's high selectivity toward P, environmental compatibility, and easy separability from water underscore its significant potential for phosphate-contaminated water remediation. The multi-functionalized La-NCF/SA-PEI demonstrate promising potential for P removal applications and advanced the development of sustainable, biomass-based adsorbents design.

Design and utilisation of a novel poly imino-phosphorane composite for the effective removal of Pb2+ and Cr3+ ions from contaminated water sources

ABSTRACT This study introduces a novel chitosan-immobilised imino-phosphorane composite (Chi-iph) for the efficient removal of lead (Pb2+) and chromium (Cr3+) from wastewater. The successful synthesis of Chi-iph was confirmed using FT-IR, XPS, BET, EDX, TGA, 1H-NMR, 13C-NMR, EI/MS, and ICP-OES analyses. Various experimental parameters such as pH, equilibrium time, metal concentration, adsorbent dose, temperature, and eluents were optimised to enhance the adsorption performance. At 25°C, with pH values of 5.5 for Pb2+ and 4.5 for Cr3+, an initial concentration of 200 mg/L, and an agitation time of 20 min, the maximum adsorption capacities were 55 mg/g for Pb2+ and 45 mg/g for Cr3+. Kinetic modelling demonstrated that the pseudo-first-order model best predicted the adsorption process, yielding capacities of 56.65 mg/g for Pb2+ and 46.38 mg/g for Cr3+. Isotherm analysis showed that the Langmuir model was a better fit than the Freundlich model, with theoretical capacities of 56.81 mg/g for Pb2+ and 44.64 mg/g for Cr3+. The Dubinin–Radushkevich (D-R) isotherm revealed adsorption energy (E) values of 9.45 kJ/mol for Pb2+ and 8.64 kJ/mol for Cr3+, indicating a chemisorption process. Theoretical saturation capacities (qD) were 56.28 mg/g for Pb2+ and 45.58 mg/g for Cr3+. Temkin isotherm results, with bT values of 9.71 and 8.53 kJ/mol for Pb2+ and Cr3+ respectively, aligned closely with the D-R model, further confirming chemisorption. Thermodynamic studies indicated that the adsorption process is exothermic, spontaneous, and more favourable at lower temperatures. Complete desorption of the heavy metals was achieved using 1 M HNO₃, allowing for efficient metal recovery. In a practical application, the Chi-iph composite removed 11.5 mg/L of Pb2+ and 7.01 mg/L of Cr3+ from contaminated wastewater, demonstrating its potential for environmental remediation. The composite’s performance aligns with WHO and FAO guidelines, making it suitable for treating wastewater before disposal into marine environments.

Lanthanum-modified sepiolite for real application of phosphate removal from rural sewage.

Being able to cause eutrophication, a severe ecological problem that leads to the demise of aquatic animals, excessive phosphate in water bodies, has been a threat to the environment. Aiming to remove phosphate from wastewater in rural areas, adsorption is a promising method. In this study, a novel phosphate adsorbent, SEP-La, was synthesized by doping lanthanum into sepiolite. Characterization and batch adsorption experiments were performed. Lanthanum was loaded on sepiolite through hydrogen bond as forms of peroxides, and it greatly enhanced the adsorption capacity of sepiolite, reaching 135.78mg/g. Pseudo-second-order kinetic model described the adsorption kinetics the best, indicating a chemisorption process. An endothermic yet spontaneous adsorption process was revealed by the fitting of the Langmuir isotherm model. The adsorbent exhibited great tolerance to pH change and interference ions. The remaining 67.82% of the original performance after 6 cycles of adsorption-desorption demonstrated its robust recyclability. Its real application potential was also manifested through column experiments using locally collected real wastewater and was able to treat 2072mL of water per gram of adsorbent, which represents a significant milestone in translating theory into practice. FT-IR, XRD, and XPS were performed to prove that its mechanism involved electrostatic interaction and ligand exchange. This work provides an affordable while auspicious phosphate adsorptive material with the potential to effectively address the issue of excessive phosphate in water at a low cost.

Computational modeling of the Nb -CO chemisorption process.

The transition metal niobium (Nb) has attracted considerable attention from the scientific community due to its intriguing electronic properties and applications in catalysts suitable for chemical reactions. Thus, this work investigates the adsorption of the atmospheric polluting gas carbon monoxide (CO) by the niobium cluster (Nb ), to describe the reactive nature of Nb . This entire study was carried out by applying the Coupled-Cluster method and Density Functional Theory (through the HSE06 functional) and the def2-QZVP plus Def2-TZVP/C auxiliary basis set functions. The results of electronic structure calculations and IR vibrational spectra suggest that both Nb and the Nb -CO clusters can be considered stable. Furthermore, the obtained results also indicate that there is a chemisorption of carbon monoxide by the Nb niobium cluster. This feature can serve as motivation for future theoretical-experimental studies, as it suggests that the Nb cluster may have possible technological applications in automotive catalytic processes. Initial three-dimensional structures were constructed. Complete optimization of the geometry was performed in coupled cluster and density functional theory methods. From the optimization configuration, it was possible to investigate the stability, chemisorption process, binding energies, charge analysis, molecular orbital energies, and IR vibrational spectra of the systems.