Pseudo-second Order Kinetic Model Research Articles

A novel zirconium glyphosine carbon nanotube composite for fast and ultraeffective In(Ⅲ) capture

Extraction of In(Ⅲ) from the tail liquid of zinc ore which possesses the large amounts of Zn(Ⅱ) and the characteristics of highly acidity, remains a critical challenge. Adsorption method can be considered as an effective and green strategy to recovery In(Ⅲ). However, the adsorption capacity of mostly reported adsorbents is unsatisfactory toward In(Ⅲ) in the acidic environment. In this work, an effective In(Ⅲ) trap is developed by using a mild, simple strategy that introduces zirconium glyphosine coordination networks in situ loaded on carbon nanotube. Benefiting from the characteristics of abundant carboxyl and phosphate groups, excellent hydrophilicity and thermal stability, the resultant zirconium glyphosine carbon nanotube composite (xZrGP-CNT) exhibits remarkable adsorption capacity (193.72 mg g-1) toward In(Ⅲ) under pH 2.5 exceeded most of the reported adsorbents, and its adsorption behavior is consistent with pseudo-second order kinetic and Langmuir isotherm models. In addition, the obtained 2ZrGP-CNT shows prominent kinetics that reaches equilibrium only within 2 h, superior selectivity and excellent regeneration performance for In(Ⅲ) capture, which indicates the highly encouraging potential for the recovery of In(Ⅲ) in practical ore fluids. Our work poses a new way to recovery of In(Ⅲ) under acidic environments with superior adsorption performance and broadens the potential of organocphosphonates for recovering In(Ⅲ).

Lead (Pb) Sorption Kinetics by Clay Minerals: Bentonite and Zeolite

Background: Heavy metal pollution chiefly lead (Pb) causes various environmental disequilibrium and health hazards. Immobilization of lead (Pb) usingclay minerals is cost effective for metal remediation due to their higher surface area and negative charges. Methods: This study was taken up to assess the Pb removal potentials of bentonite and zeolite from contaminated water and to study the effect of sorbent dosage, initial Pb2+ concentrations and incubation time intervals on Pb adsorption and desorption was studied. Result: Zeolite was effective in immobilising Pb (78.0%) than bentonite (70.9%) which increased with increasing sorbent dosage and time intervals. The pseudo second-order kinetic model described the Pb adsorption precisely. Chemisorption was the dominant mechanism operating in aqueous solution system, hence, it could be concluded that zeolite can be utilized as an efficient sorbent for wastewater treatment.

Enhanced uranium removal from leach liquor using raw and activated sludge as sustainable adsorbents

ABSTRACT To eliminate uranium from sulphate leach solution, this study introduces an economical, environmentally friendly adsorbent derived from dewatered municipal sludge (RS) and activated (AS) using calcium oxide. Various analytical methods, including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), Brunauer – Emmett – Teller (BET) analysis, and X-ray fluorescence spectroscopy (XRF), were employed in the characterisation of both materials. The efficacy of these adsorbents in removing uranium from sulphate leach fluid was systematically explored resulting in the achievement of a maximum adsorption capacity of 33.0 mg g−1 and 60.2 mg g−1 for RS and AS respectively. These adsorption capacity were detected using the following operational parameters: solution pH equals 2.0, 240 min as a contact time between the adsorbent and U(VI) solution, U(VI) initial concentration of 250 mg L−1, adsorbent dosage of 5.0 g L−1 and room temperature. The pseudo-second order kinetic and Langmuir isotherm models were determined to be the most suitable for the U(VI) adsorption process, showing a chemisorption, monolayer, and uniform process for the uranium adsorption by both materials. Using 1.0 M hydrochloric acid, over 96% of the U(VI) was successfully desorbed from the loaded sorbent, and AS sorbent held its stability for six sorption/desorption cycles in a row. Overall, this study offers a promising solution for sewage sludge disposal while addressing economic and environmental concerns.

Peptides-modified cellulose microspheres for adsorption of ochratoxin A: Performance and mechanism

In this study, peptides with ochratoxin A (OTA) recognition and adsorption capability were designed, among which lysine, histidine, arginine and tyrosine were crucial. Peptide CYFRFYSNLHPK showed the strongest affinity for OTA (Ka = 1.74 × 105 M−1). Theoretical calculations revealed that the differences in the affinity of peptides for OTA were attributed to differences in the type, number and position of amino acids residues. Peptides were conjugated with porous cellulose microspheres to form peptide-modified pretreatment materials (Pep-MPA-RCMs) for adsorption of OTA. The morphology and composition of the prepared Pep-MPA-RCMs were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, thermogravimetric analysis and X-ray diffraction. The effects of pH, adsorption time, initial concentration and temperature on the adsorption process were investigated. The adsorption performance was correlated with the pseudo-second order kinetic and Sips adsorption isotherm model. Thermodynamic studies further proved that the adsorption was exothermic and the prepared Pep-MPA-RCMs showed the maximum adsorption capacity of 9.87 mg/g for OTA at 25℃. A simple adsorption column for OTA was prepared by using Pep-MPA-RCMs as filler material, which still maintained more than 80 % of the removal rate after five consecutive adsorption-elution cycles. The prepared pretreatment material was successfully applied to remove OTA in real samples and was a promising adsorbent for practical applications.

Comparison of two carbonaceous supported Fe-rich adsorbents for arsenate removal: A functionalisation and mechanistic study with applicability to groundwater treatment

The presence of arsenic in groundwater, and through this in drinking water, has been shown to present a serious risk to public health in many regions of the world. In this study, two iron-rich carbonous adsorbents were compared for the removal of arsenate (As(V)) from groundwater. Biochars (FeO-biochar and FeO-pyrochar) derived from biomass waste were functionalised in two different ways with iron chloride for comparation. Batch and dynamic parameters were optimised to achieve >99% As(V) removal efficiency. Experimental data were best described by the pseudo-second order kinetic model, while multi-stage diffusion appeared to limit mass transfer of As(V). Among the isotherm models evaluated, the Freundlich model best described the experimental results with high correlation coefficients (R2 ≥ 0.94) for both adsorbents. Monolayer adsorption capacities were found to be 4.34 mg/g and 8.66 mg/g for FeO-biochar and FeO-pyrochar, respectively. Batch studies followed by instrumental characterisation of the materials indicated the removal mechanisms involved to be electrostatic interactions (outer-sphere), OH− ligand exchange (inner-sphere complexation) and hydrogen bonding with functional groups. Higher pHpzc (9.1), SBET (167.2 m2/g), and iron/elemental content for the FeO-pyrochar (compared with the FeO-biochar) suggested that both surface chemistry and porosity/surface area were important in adsorption. Dynamic studies showed FeO-pyrochar can be used to remove As(V) from groundwater even at low ‘environmental’ concentrations relevant to legislative limits (<10 μg/L), whereby 7 g of FeO-pyrochar was able to treat 5.4 L groundwater.

Green-synthesized, biochar-supported nZVI from mango kernel residue for aqueous hexavalent chromium removal: Performance, mechanism, and regeneration

A biochar-supported green nZVI (G-nZVI@MKB) composite was synthesized using mango kernel waste with “dual identity” as reductant and biomass of biochar. The G-nZVI@MKB with a Fe/C mass ratio of 2.0 (G-nZVI@MKB2) was determined as the most favorable composite for hexavalent chromium (Cr(VI)) removal. Distinct influencing parameters were discussed, and 99.0% of Cr(VI) removal occurred within 360 min under these optimized parameters. Pseudo-second order kinetic model and intra particle diffusion model well depicted Cr(VI) removal process. The XRD, FTIR, SEM and XPS analyses verified the key roles of G-nZVI and functional groups, as well as the primary removal mechanisms involving electrostatic attraction, reduction, and complexation. G-nZVI@MKB2 exhibited a good stability and reusability with only a 16.4% decline in Cr(VI) removal after five cycles. This study offered evidence that mango kernel could be recycled as a beneficial resource to synthesize green nZVI-loaded biochar composite for efficient Cr(VI) elimination from water.

Solventless synthesis of bixbyite (Mn2O3) and hausmannite (Mn3O4) nanoparticles for ammonia nitrogen removal

Excessive accumulation of ammonia nitrogen (AN) in water resources poses serious health effects to humans, and control of its discharge in wastewater has been a primary global concern. Therefore, it has to be removed by robust, eco-friendly, and cost-effective approaches. In this study, Mn2O3 and Mn3O4 nanoparticles (NPs) were facilely synthesized by solid-state thermolysis, and characterized by XRD, FTIR, SEM, and TEM techniques. XRD results revealed the formation of single-phase cubic bixbyite, Mn2O3 and, tetragonal hausmannite, Mn3O4 nanoparticles exhibiting crystallite size of 27.69 and 19.38 nm, respectively. Morphological analysis shows the formation of agglomerated nanoparticles with varying shapes. The experimental isotherm results indicated that AN sorption by Mn2O3 could be well described by Freundlich model, indicating multilayer adsorption on heterogeneous surface. Contrarily, AN adsorption by Mn3O4 was consistent with the Langmuir model, representing a monolayer physisorption process on a homogeneous surface. The pseudo-first-order kinetic model fitted well to the experimental data than the pseudo-second order kinetic model. The Langmuir sorption capacities (qm) for Mn2O3 and Mn3O4 were 23.642 mg/g and 52.779 mg/g, respectively. Thermodynamic experimental kinetic data demonstrated that AN adsorption on the two forms of manganese oxides was an exothermic and spontaneous process. Regeneration experiments inferred that both Mn2O3 and Mn3O4 adsorbents could be reused.

Cost-effective synthesis of magnetic graphene oxide nanocomposite from waste battery for the removal of arsenic from aqueous solutions: Adsorption mechanism with DFT calculation

In this study, magnetic graphene oxide (MGO-Fe3O4) nanocomposite was prepared by co-precipitating of FeCl3.6H2O and FeCl2.4H2O on waste battery-derived graphene oxide and used as an adsorbent for the efficient removal of As(III) from aqueous solutions. The prepared nanocomposite was characterized by Fourier transformed infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, zeta potential, and a vibrating sample magnetometer. These characterizations revealed that spare like Fe3O4 nanoparticles (10.5 nm) were decorated on graphene oxide nanosheets and showed excellent saturation magnetization (89.73 emu/g). The adsorption of As(III) by MGO-Fe3O4 was optimized by analyzing various parameters. Experiments showed that 98 % of As(III) was removed at neutral pH in a just 20 min, even though the adsorbent dose was only 0.14 g/L. The adsorption kinetic and isotherm were best fitted with the pseudo-second order kinetic and Frendlich isotherm model. The maximum adsorption capacity (qmax) was found to be 50.2 mg/g at room temperature. Thermodynamic studies showed that the As(III) adsorption process was spontaneous and exothermic in nature. The enhanced adsorption capacity and magnetic properties of MGO-Fe3O4 are crucial in the drinking water treatment process due to the easy magnetic separation of MGO-Fe3O4 from aqueous solution after the adsorption process. Density Functional Theory (DFT) was also used to investigate the interaction between MGO-Fe3O4 and As(III), which further suggested that MGO-Fe3O4 and As(III) mostly interact with each other through surface complexation and hydrogen bonding.

UPTAKE OF Co(II), Pb(II) AND Ni(II) IONS BY Annona senegalensis STEM BARK BIOCHAR FROM AQUEOUS SOLUTION: OPTIMIZATION, KINETIC AND THERMODYNAMIC STUDIES

The concern for heavy metal pollution in the environment is especially so since they are non-biodegradable. The use of agro materials in the removal of these heavy metal pollutants has been recognized as a low-cost alternative to the costly conventional remediation techniques. The equilibrium sorption of the chemically activated Anonna senegalensis stem bark was investigated. Using standard techniques, the physicochemical properties of activated carbon (MAASC) were ascertained. By using a simultaneous batch adsorption approach, the adsorption of Co2+, Pb2+, and Ni2+ onto MAASC was examined as a function of pH, solution temperature, initial metal ion concentration, agitation time, adsorbent dose, particle size, and carbonization temperature. The equilibrium sorption data generated were fitted into Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models as well as pseudo first-order, pseudo-second-order and intraparticle diffusion kinetic models. From the obtained results, it was discovered that the Langmuir isotherm provided the best match conformation of all the models, except for Pb2+, which was best for Freundlich with an R2 of 0.95. Physisorption was shown to be the mechanism by Dubinin-Radushkevich. For Co2+, Pb2+, and Ni2+, respectively, the pseudo second-order kinetic model had R2 values of 0.997, 0.999, and 0.999 that best matched the data. Both intraparticle diffusion and the boundary layer effect also contributed to regulating the rates of the adsorption process. The study's thermodynamic results showed that Ho for Co2+, Pb2+, and Ni2+ were 27.51, 19.70, and 13.37 KJ/mol, respectively. These values are all positive and suggest an endothermic reaction, supporting the physisorption mechanism.

Removal of Humic Acid from Water by Adsorption Using Chitosan and Metal Organic Framework ZIF 8 Loaded Chitosan Adsorbents

Water is the most necessary need for life on the earth. There are a lot of organic pollutants in water. One of the organic pollutants is natural organic substances. Humic acid, a natural organic substance, turns into very harmful substances along with other pollutants. In this study, the humic acid removal from aqueous solution by adsorption using chitosan and chitosan/ZIF 8 composite spheres was examined. Chitosan spheres cross-linked with epichlorohydrin (ECH) and composite spheres consisting of metal organic framework ZIF8 and chitosan were prepared as adsorbents. Equilibrium, kinetic, and thermodynamic studies were investigated for humic acid adsorption by pristine chitosan-ECH and composite chitosan/ZIF 8 adsorbents. Chemical adsorption was found to be compatible with the Freundlich isotherm model and the pseudo-first-order kinetic model for pure chitosan adsorbents. Studies were carried out using chitosan/ZIF8 composite adsorbent, and the most suitable models for chemical adsorption were determined as Langmuir isotherm and pseudo-second order kinetic model. The response surface method was applied with the design expert program to determine the optimum experimental conditions. The adsorption tests were carried out using chitosan-ECH, ZIF 8 and chitosan/ZIF 8 adsorbents for specified optimum conditions, and the humic acid removal was determined as 95.1%, 98.3%, and 97.3%, respectively. In addition, desorption was performed using chitosan-ECH and chitosan/ZIF 8 spheres, and the desorption efficiency was found to be 20.9% and 82.5%, respectively. It has been observed that the developed adsorbents have potential in removing humic acid from water.

By-product Eucalyptus leaves valorization in the basic dye adsorption: kinetic equilibrium and thermodynamic study

Abstract Algerian Eucalyptus Leaves (AEL), a natural biodegradable adsorbent abundantly available, was used for the removal of methylene blue (MB) dye. The AEL properties for the removal of MB were investigated under different conditions by varying the AEL amount, MB concentration, pH of the solution and the reaction temperature. Scanning electron microscopy (SEM) and infrared spectroscopy (FTIR) techniques have been used to characterize AEL biosorbent. Experimental results showed that the adsorption of MB dye at the concentration of 50 mg L−1 reached to 91 % at pH 10 with a stirring speed of 200 rpm and after 180 min of reaction time. The experimental data were analyzed using the linear forms of different kinetic models (pseudo-first order kinetic model, pseudo-second order kinetic model, and intra-particle diffusion models). The results demonstrated that the adsorption kinetics of MB was consistent with the pseudo-second order model with R 2 value of 0.9969. The isotherm models Langmuir, Freundlich, Dubinin, Elovich, Brunaut Emmet Teller and Temkin models were also investigated to describe the adsorption equilibrium. The results show that the AEL adsorption is in accordance with Temkin isotherm. The thermodynamic study revealed that the adsorption is spontaneous and exothermic. Therefore, as a cheap green adsorbent with high MB adsorption performance, AEL is expected to become one of the best candidate materials for future industrial wastewater treatment.

Investigating the sorption behavior of selenite on commercial partially oxidized magnetite nanopowder under aerobic conditions: Characterization and mechanisms

Selenium, which belongs to essential elements, has a narrow margin between necessity and toxicity. Anthropogenic activities may lead to its elevated concentrations in aquatic ecosystems, particularly in the undesirable form of toxic selenite, due to its high environmental mobility. Hence, it is imperative to devise effective technologies to limit its potential migration through the environment. Therefore, the development and evaluation of new adsorbents for its effective removal from selenium-contaminated waters are crucial for both human health and environmental stability in affected areas. Specifically, magnetite-based nanomaterials showed promise as sorbents due to their capacity to immobile contaminants through reductive transformation or adsorption, but there is a lack of comprehensive understanding regarding the sorption mechanisms and the factors influencing the efficiency of this process. A deeper understanding of these factors is crucial for developing sustainable and efficient water treatment strategies. This study focuses on magnetite nanopowder’s sorptive properties, examining critical factors such as pH, ionic strength, and competing anions that affect selenite removal. Sorption kinetics revealed an initial rapid selenite removal followed by a slower, time-dependent phase, suggesting a complex sorption mechanism. Chemisorption was considered the primary sorptive interaction, with diffusion playing a minor role, and was best described by the pseudo-second order kinetic model. Notably, pH significantly affected sorption efficiency and the suggested sorptive mechanism. Acidic conditions favored selenite removal due to formation of inner-sphere complexes, while alkaline conditions reduced efficiency due to repulsive interactions. Equilibrium sorption data were best fitted by the Langmuir model, with maximum sorption at pH 3, indicating that acidic conditions favor selenite removal. X-ray photoelectron spectroscopy (XPS) analysis ruled out the formation of reduced selenium compounds on the magnetite nanopowder surfaces. Additionally, Mössbauer spectrometry revealed that the nanopowder is not homogeneous and contains both magnetite and maghemite phases. Ionic strength and co-occurring ions showed minimal chloride impact but significant phosphate competitiveness due to its affinity for iron oxides. In conclusion, this study sheds light on the complex selenite sorptive interactions with magnetite nanopowder, emphasizing the dominance of chemisorption, especially in acidic solutions.

The simultaneous removal of methylene blue (MB) and Ca2+ by recyclable adsorbents based the scales derived from coal gasification system.

The transformation of solid wastes from industrial production into effective adsorbents could significantly contribute to wastewater treatment. In this study, after acidizing and burning soft scale (SS) from coal gasification system, two magnetic adsorbents (mag-ASS and mag-BASS) were prepared via the combination of magnetite with ultrasonic, respectively. The treatment effects of mag-ASS and mag-BASS were then investigated for simulated wastewater containing macromolecular organic matter [i.e., methylene blue (MB)] and Ca2+. The results indicated that the pseudosecondorder kinetic, Elovich, Freundlich,Langmuir and Temkin model could well describe the adsorption behavior of MB and Ca2+ onto mag-ASS and mag-BASS. The maximum adsorption capacities of mag-ASS for MB and mag-BASS for Ca2+ were 600.53mg/g and 102.54mg/g, respectively. Surprisingly, the adsorption abilities of mag-ASS for MB and mag-BASS for Ca2+ showsignificantly higher than the others. The adsorption mechanisms of MB mainly included electrostatic interaction, π-π conjugate interaction and cation exchange, while those of Ca2+ were mainly electrostatic interaction and cation exchange. The diffusion of MB and Ca2+ onto the magnetic adsorbents might be controlled by the combined effects of intraparticle and liquid film diffusion. There was no significant reduction in adsorption capacity after 8 cycles of adsorptionand desorption, indicating that SS-based magnetic adsorbents had good recyclability and stability. Moreover, the removal efficiency of mag-BASS for total hardness and total organic carbon in real coal gasification gray water (CGGW) was 82.60 and 64.10%, respectively. The treatment of CGGW and theresource of wastes would significantly promote the reasonable disposal of coal gasification scales.

Preparation of Zn/Zr-MOFs by microwave-assisted ball milling and adsorption of lomefloxacin hydrochloride and levofloxacin hydrochloride in wastewater

The Zn/Zr-MOFs were synthesized via microwave-assisted ball milling and subsequently characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The thermal stability of the Zn/Zr-MOFs was evaluated through thermogravimetry (TGA). The results demonstrated the exceptional adsorption properties of the Zn/Zr-MOFs towards Lomefloxacin hydrochloride and Levofloxacin hydrochloride. At a concentration of 30 ppm for Lomefloxacin hydrochloride, the addition of 30 mg of Zn/Zr-MOFs material resulted in an adsorption capacity of 179.2 mg•g−1. Similarly, at a concentration of 40 ppm for Levofloxacin hydrochloride, the addition of 30 mg Zn/Zr-MOFs material led to an adsorption capacity of 187.1 mg•g−1. Kinetic analysis revealed that the experimental data aligned well with a pseudo-second order kinetic model. Overall, these findings highlight the significant potential application of Zn/Zr-MOF materials in wastewater treatment.

Modification of amino functionalized silica nanoparticles with L-proline and furanacrylic acid as novel composites for the efficient removal of methyl orange

The present study deals with the preparation of new composites in which L-proline (LP) and furnacrylic acid (FA) have been grafted on surface of amino functionalized silica nanoparticles (AFS). At first, AFS were prepared by sol-gel approach using tetraethoxysilane (TEOS) as silica source and aminopropyltriethoxysilane (APTES) as silica modifiers. Taking the advantage of amino group on AFS surface, LP and FA were easily grafted on silica surface to obtain LP grafted silica (AFS-LP) and FA grafted silica (AFS-FA) nanocomposites by post modification approach. As prepared composites were characterized by FTIR, SEM, XRD and TGA. The evidence of LP and FA on AFS was elucidated from the FTIR bands found at 1650–1698 cm−1 related to carbonyl group CO) of amide. Additionally, peaks observed at 2965 cm−1 (C-H stretching) of propyl groups and at 1050 cm−1 (Si-O-Si) indicated that the backbone of the material is preserved as silica. The micro images of SEM depicted that the AFS are spherical in shape and have more degree of monodispersivity whereas the SEM images of composites (AFS-LP and AFS-FA) have larger particle size and less degree of monodispersivity. Likewise, XRD peaks at 2θ (∼12°) revealed the mesoporosity of silica as well as hybrid silica and further depression in this peak in case of AFS-LP and AFS-FA depicted the existence of organic moieties on silica. TGA analysis depicted three decomposition steps (high weight loss) in case of AFS-LP and AFS-FA in contrast to two decomposition steps observed in case of AFS. The higher weight loss observed in the case of hybrid composites depicted the grafting of organic molecules on AFS. The prepared composites AFS-LP and AFS-FA were deployed to investigate their adsorption capacity to remove methyl orange (MO) from aqueous media. Experiments revealed that the composites have high adsorption capacity in acidic media (pH=2) with % removal of 85.05 % for AFS-LP and 81.70 % for AFS-FA. The experimental data was evaluated for adsorption isotherms and value of correlation factor (R2) was close to unity in case of Freundlich representing that the adsorption follows Freundlich isotherm. The data was also evaluated for kinetic models and higher values of R2 as well as closeness of experimental and calculated values of Qe predicted that adsorption of MO followed pseudo-second order kinetic model.

Adsorption of phosphate over a novel magnesium-loaded sludge-based biochar.

The production of sludge-based biochar to recover phosphorus (P) from wastewater and reuse the recovered phosphorus as agricultural fertilizer is a preferred process. This article mainly studied the removal of phosphate (PO4-P) from aqueous solution by synthesizing sludge-based biochar (MgSBC-0.1) from anaerobic fermentation sludge treated with magnesium (Mg)-loading-modification, and compared it with unmodified sludge-based biochar (SBC). The physicochemical properties, adsorption efficiency, and adsorption mechanism of MgSBC-0.1 were studied. The results showed that the surface area of MgSBC-0.1 synthesized increased by 5.57 times. The material surface contained MgO, Mg(OH)2, and CaO nanoparticles. MgSBC-0.1 can effectively remove phosphate in the initial solution pH range of 3.00-7.00, with a fitted maximum phosphorus adsorption capacity of 379.52 mg·g-1. The adsorption conforms to the pseudo second-order kinetics model and Langmuir isotherm adsorption curve. The characterization of the adsorbed composite material revealed the contribution of phosphorus crystal deposition and electrostatic attraction to phosphorus absorption.

The production of a novel adsorbent from forest waste (Platanus orientalis L.) for dye adsorption: Adsorption process optimization and experimental design

In the study, a novel activated carbon material was produced using forest waste commonly found in nature. The activation was completed by modifying the surface of the material with H3PO4. Using this adsorbent material, we investigated the adsorption of the hazardous dyestuff, methylene blue, from the water environment. The adsorbent was characterized using BET, SEM, and FT-IR analyses. The characterization processes revealed that the adsorbent has a wealth of functional groups and many cavities and protrusions on its surface. Moreover, according to the BET analysis result, it was observed that it is an adsorbent with a high surface area (876.01 m2 g−1). Kinetic, equilibrium and thermodynamic studies have been conducted to fully understand the nature of methylene blue adsorption. The pseudo-second order kinetic model best represents the adsorption process data, and the Langmuir isotherm aligns with the equilibrium data. According to the Langmuir isotherm data, the maximum adsorption capacity (qmax) was determined to be 198.01 mg g−1. The thermodynamic results showed that the process of adsorption of methylene blue on various surfaces is spontaneous and occurs via physisorption. Additionally, in addition, the effects of the parameters (adsorbent dose, time, and concentration) determined for the methylene blue adsorption process were optimized using the surface response method. Activated carbon from plane tree fruits (Platanus orientalis L.) has the potential to be a novel adsorbent due to its unique surface morphology and strong adsorption capabilities.

Synthesis of Na-Alginate templated Montmorillonite-Silica Composite as adsorbent for removal of Rhodamine B

AbstractIn this study, mesoporous Montmorillonite-Silica composites prepared by using different amount Alginate as sacrificial template, for removal of Rhodamine B is investigated. By alternating Alginate amount it is aimed to switch the porosity of adsorbents thus the adsorption capacities of adsorbents. Synthesized adsorbents had been characterized by using Scanning Electron Microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and N2-Ads/Des techniques. It is observed that beside the decrease in the micropore volume, the total pore volume of the adsorbents increased with the increasing of used Alginate amount. The total pore volumes of adsorbents synthesized with different Clay/Alginate ratio (10, 5, 1) were found as 0.116, 0.172, and 0.178 cm3/g, respectively. Batch adsorption studies showed that the maximum removal efficiencies were obtained at acidic conditions and the adsorbents had better fit with Freundlich isotherm. Qm values obtained from Langmuir isotherm were found as 24.47, 31.97 and 28.48 mg/g for synthesized adsorbents. Also, adsorption kinetic studies showed that for all adsorbents, experimental data had good fit to the pseudo-second order kinetics model. The model parameters were found as 5.9,6.3 and 6.5 (10–3 g/ (mg min). Thermodynamic parameters were also investigated in the study. Negative ∆Go values pointed out that the adsorption of RhB onto synthesized adsorbents was favorable process. Positive values of ∆Ho and ΔS indicated that the adsorption of RhB on adsorbents were endothermic and rising of randomness during the adsorption of RhB on the surface of the adsorbent. Adsorbents could be recovered at least five times without significant decrease in adsorption capacity.

Efficient removal of the organophosphate pesticide, profenofos using polymer-stabilized microporous Fe2O3-ZnO nanocomposite: Kinetic and thermodynamic analysis

In the contemporary landscape of scientific research, the development of inhibitors for acetylcholinesterase (AChE) holds significance due to their dual application as chemical warfare agents (CWAs) and pesticides. These compounds, whether intentionally deployed for malicious purposes, used in agriculture to combat pests, or accidentally released, pose a substantial threat to humanity. Consequently, there is a dire need to create efficient nanocatalysts capable of eliminating organophosphate toxic substances. This study focuses on the synthesis of a nanocomposite catalyst comprised of polymer-stabilized Fe2O3-ZnO, characterized as porous oval-shaped clusters that exhibit exceptional proficiency in the degradation of the pesticide profenofos (PF). This degradation process is remarkably swift, occurring within a short timeframe under both dark and light conditions. Porosity enhancement was achieved through the combination of polymeric stabilizing agents, namely polyvinylpyrrolidone (PVP) and methyl cellulose (MC). Notably, the highest concentration of profenofos (1825 mg/L) was directly introduced to the Fe2O3-ZnO nanocomposite catalyst. Remarkably, 100 % degradation was achieved within just 60 min in the absence of light, highlighting the feasibility of dark treatment as an effective degradation pathway. The kinetics of the reaction were evaluated using Lagergren pseudo-first order and Ho/McKay pseudo-second order kinetic models, employing varying catalyst doses and profenofos concentrations. The results indicated that the reaction predominantly follows second-order kinetics. Furthermore, thermodynamic parameters, including the change in Gibbs free energy (ΔG), entropy (ΔS), and enthalpy (ΔH), were assessed, revealing the spontaneous and exothermic nature of the reaction. Additionally, a proposed degradation pathway for the chemical warfare agent stimulant, profenofos, was elucidated. To our knowledge, this is the inaugural documentation showcasing the remarkable efficiency of a polymer-stabilized Fe2O3-ZnO nanocomposite catalyst in degrading the organophosphate pesticide, profenofos, achieving rapid degradation rates even under dark conditions. The findings contribute to the advancement of catalytic materials for environmental remediation and provide important insights into the kinetics, thermodynamics, and degradation pathways of organophosphate compounds.

Ni2+ removal by ion exchange resins and activated carbon: a benchtop NMR study

AbstractHeavy metal pollution in water is a critical environmental concern, demanding effective remediation techniques. Traditional methods, including ion exchange and adsorption, often rely on inductively coupled plasma (ICP) atomic emission spectroscopy/mass spectrometry (AES/MS) for the indirect and time-consuming measurement of residual metal concentrations. In contrast, this study employs innovative direct monitoring of nickel removal by benchtop NMR relaxometry using the paramagnetic properties of Ni2+. To prove the feasibility of the NMR follow-up of Ni2+ uptake, batch experiments were performed with Amberlite IR120, Amberlite IRC748, Dowex Marathon MSC, and activated carbon (AC), which were previously characterized by various techniques. The effect of contact time, pH, and Ni2+ concentration on removal efficiency were studied. Pseudo-first and pseudo-second order kinetic models were used. The Langmuir model effectively described the equilibrium isotherms. The longitudinal and transverse relaxation curves of the loaded resins were biexponential. For sulfonic resins, a strong correlation was observed between the relaxation rates of the fast-relaxing fraction and the Ni2+ content determined by ICP-AES/MS. For IRC748, the effect of Ni2+ loading on the relaxation rates was weaker because of Ni2+ complexation. The relaxation curves of loaded AC revealed multiple fractions. Centrifugation was employed to eliminate the contribution of intergranular water. The remaining intragranular water contribution was biexponential. For high Ni2+ loadings, the relaxation rates of the slow relaxing fraction increased with the AC Ni2+ content. These results mark the initial stage in developing a column experiment to monitor, in real-time, adsorbent loading by NMR relaxometry.