Langmuir Isotherm Research Articles

Integrated adsorption and electrochemical sensing of Th(IV) ions using graphene oxide and chitosan decorated magnetite-based adsorbent.

Nuclear waste management is a crucial aspect as the most significant threat to the ecosystem is caused by radioactive waste in which thorium contamination remains a prominent issue. This work represents an integrated approach for the elimination of thorium through the adsorption technique and subsequent electrochemical sensing using Magnetite@Graphene Oxide@Chitosan (M@GO@Cs). Moreover, the sorption of Th(IV) ions is optimized through batch studies, which are consistent with the results derived from ANOVA using the Box-Behnken Design model, and the ideal parameters resulted in 95.79% removal efficiency of Th(IV) ions using 6 mg of adsorbent in 10 mL of 50 mg/L Th(IV) ions solution at a pH of 5 within 20 min. Maximum adsorption capacity (833.33 mg/g) is obtained from Langmuir adsorption isotherm and process was aligned with the pseudo-second-order kinetic model. M@GO@Cs exhibited high recyclability sustaining high performance across nine consecutive adsorption-desorption cycles while maintaining excellent removal efficiency upto 85%. Furthermore, the electrochemical characterization of the synthesized M@GO@Cs nanoadsorbent was studied using the Cyclic Voltammetry, and Electron Impedance Spectroscopy techniques and quantification of Th(IV) ions was done utilizing the Differential Pulse Voltammetry method with the Limit of Detection (LOD) of 0.2 mg/L within a linear range of 10-100 mg/L.

Biodegradable genipin cross-linked chitosan/pea protein isolate sponges for effective adsorption of methyl blue: Batch experiments and quantum chemical analysis

This study successfully prepared double crosslinked chitosan (CS) and pea protein isolate (PPI) composite sponges using genipin as a crosslinking agent and investigated their effectiveness as an adsorbent for methyl blue (MEB) in aqueous solutions. The composite sponges were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller measurement, swelling tests, gel fraction measurement, zeta potential, and X-ray diffraction. Additionally, the effects of genipin content, pea protein isolate content, sponge dosage, initial pH of the solution, adsorption time, dye concentration, and adsorption temperature on dye removal ability were studied. The results showed that at pH 3.0 and a dye concentration of 100 mg/L, the adsorption capacity of the sponge for methyl blue was found to be 351.6 mg/g. At 298 K and after 720 min, with a dye concentration of 700 mg/L, the maximum adsorption capacity of the sponge for methyl blue reached 959.3 mg/g. The adsorption process follows a pseudo-second-order kinetic model and a Langmuir isotherm. Theoretical analysis using density functional theory suggests that the adsorption of methyl blue by the composite sponge is attributed to the anionic sulfonic acid group of the dye. The composite sponge degraded 76.1 % after being buried in soil for 21 days. This study reveals the enormous potential of biodegradable chitosan-protein-based sponges in effectively removing methyl blue dye pollutants from wastewater.

Potential of water-soluble chitosan Schiff bases extracted from Metapenaeus dobsoni shells as effective corrosion inhibitors

Corrosion causes significant economic losses and structural failures in industries, highlighting the need for eco-friendly inhibitors. Chitosan (CS), a biodegradable and non-toxic biopolymer, shows potential, though its limited water solubility restricts its applications. To overcome this challenge, this study presents the synthesis of two water-soluble chitosan Schiff bases (CSBs) derived from the shells of Metapenaeus dobsoni (M. dobsoni). The extracted CS exhibits a remarkable degree of deacetylation exceeding 95 %, which was subsequently modified through reactions with o-vanillin (2-hydroxy-3-methoxybenzaldehyde) (CSB I) and 2,3-dihydroxybenzaldehyde (CSB II). Structural characterization using spectroscopic techniques confirmed the successful formation of CSBs. Electrochemical measurements were employed to assess the corrosion resistance of mild steel in 0.5 M HCl with varying concentrations of CSB I and CSB II. The results revealed superior corrosion inhibition by CSB II (% IE = 94.48 %) compared to CSB I (% IE = 88.80 %). The methoxy group in CSB II contributed to its higher electron density and enhanced adsorption, leading to better surface coverage and corrosion resistance. Both inhibitors followed the Langmuir isotherm, suggesting a mix of physisorption and chemisorption. These CSBs are promising for corrosion control in industries like pipelines, storage tanks, construction materials, and acid pickling.

Effectiveness of Musa Balbisiana bract toward chromium removal from industrial tannery effluent: optimization, kinetics, isotherms, regeneration, and cost estimation

Eradicating chromium from industrial effluent is essential for environmental security and economic reasons. This study investigates the potency of activated Musa balbisiana bract biomass as a biosorbent to remove hexavalent chromium (Cr6+) from real industrial tannery effluent (ITE). The characterization study exemplifies the existence of irregular structures and excessive cavities, and the occurrence of functional groups (hydroxyl, carboxyl, esters, and alkynes) are benefitting the deposition of Cr6+ on the biosorbent. A maximum biosorption capacity of 42.75 ± 0.21mg/g was observed at an optimum pH of 6.5, biosorbent dosage of 0.3g, initial Cr6+ concentration of 50mg/L, and contact time of 120min. The validation experiment confirmed the removal efficiency of total chromium, trivalent chromium, and Cr6+ 92.56 ± 0.80%, 98.63 ± 0.20%, and 96.21 ± 0.50%, respectively. Among the models, Langmuir isotherm (R2: 0.9992) and pseudo-second order (R2: 0.9999) kinetic models greatly correlate with the equilibrium data. A 2-tier membrane module was examined for continuous study and reached 88.23 ± 0.60% Cr6+ removal. Statistical analysis was performed to confirm the significance of adsorption results. The likelihood of the desorption and regeneration of the treated biosorbent was investigated. The estimated cost per volume of ITE treated and unit of pollutant removal from ITE employing Musa balbisiana bract biosorbent is around $3.08/m3 and $3.75/kg.

Visible light photocatalytic reduction of Toxic Chemical Organophosphate Monocrotophos using reduced Graphene Oxide derived from bamboo leaves

In this study, graphene oxide (GO) was synthesized from waste bamboo leaves using a pyrolysis and ultra-sonication technique. UV-visible spectroscopy revealed a prominent absorption peak at 230nm, while Raman spectroscopy confirmed the presence of characteristic D-band (1340cm⁻¹) and G-band (1596cm⁻¹). XRD analysis showed a peak at 11.5°, corresponding to a lattice spacing of 3nm, and SEM/TEM imaging demonstrated the formation of multi-layered graphene sheets. The synthesized GO was evaluated for the photocatalytic degradation of the organophosphate pesticide monocrotophos under visible light. At a concentration of 25mg/L, graphene exhibited a removal efficiency of 98% with a degradation rate of 0.036 ppm/min, following a Langmuir isotherm and pseudo-first-order kinetic model. The significance of this study lies in the potential environmental application, offering an economical and sustainable solution for the decontamination of pesticide-contaminated water sources. The method could contribute significantly for reducing environmental pollution and addressing global water safety challenges.

A new strategy toward synthesis of novel bifunctional N- and S-bearing sorbent for platinum(IV) removal from aqueous solutions and acidic leaching residue of Pt/Al2O3 catalyst

Strong incentive politics have been elaborated for promoting the recovery of precious metals from secondary resources. Solid leaching generates acidic effluents that can be pre-treated using precipitation steps for partial separation before applying sorption for metal recovery from mild acidic solutions. For this purpose, a new sorbent was designed bearing numerous N- and S-bearing reactive groups with good affinity for platinum (as chloroanionic species). Thiazole precursors were first reacted before being grafted (by free radical reaction) with triallyl cyanurate (to form CTTR sorbent). The material was characterized by a series of analytical tools (SEM, BET, FTIR, XPS, TGA, elemental analysis, and titration). The effect of pH combined with FTIR and XPS spectroscopy analyses allowed identifying the mechanisms involved in metal binding: (a) electrostatic attraction of chloroplatinate anions with protonated amine groups (especially in acidic conditions), (b) while at moderate acidic pH metal sorption proceeds through ligand exchange and chelation onto N-based and S-based groups. Optimum sorption was found at pH close to 4 (near pHpzc value). Under selected experimental conditions, the equilibrium was reached in 25–35 min. The pseudo-first order rate equation fitted well experimental profile (though the resistance to intraparticle diffusion contributes to the kinetic control). The maximum sorption capacity at room temperature reached up to 1.58 mmol Pt g−1 (at pH 4). The sorption isotherm was successfully fitted by the Temkin equation. The sorption is spontaneous and exothermic (with reduction in maximum sorption capacity reaching up to 25 %, when temperature increases to 50 °C). Optimum platinum desorption was obtained with 0.3 M HCl solution (with solid/liquid ratio 1.67 g L−1) for complete desorption and enrichment factor close to 4.6. Complete desorption was maintained over 5 cycles, while the sorption efficiency decreased by less than 3.5 % at the fifth cycle. The sorbent showed remarkable stability for PGMs (Pd(II) in addition to Pt(IV)) against alkali-earth elements or base metals (from equimolar synthetic solutions); the selectivity is driven by the preference of the reactive groups (soft base and intermediary base) for soft PGM metals against hard and borderline metal ions; this selectivity is also affected by metal speciation (formation of chloro-anionic species). The valorization of platinum from non-compliant Pt/Al2O3 catalyst was investigated after leaching with aqua regia. Platinum was precipitated from the leachate with ammonium chloride. In a second step, aluminum was removed by precipitation at pH 5. The residual solution was then treated by adsorption on CTTR: optimum separation between Pt and Al was achieved at pH ≈ 3.

Eco-friendly property modulation of biobased gels of carboxymethyl cellulose-integrated poly(tertiary amine)s for the removal of azo-food dyes

Anionic polysaccharide-based gels enable the design of biobased materials with biochemical properties, non-toxic and natural origin. A new set of cationic gels was prepared from carboxymethylcellulose (CMC)-doped tertiary amino functional cationic monomers 2-(dimethylamino)ethyl methacrylate and N-(3-(dimethylamino)propyl) methacrylamide via the formation of semi-interpenetrated network (semi-IPN) at different polymerization temperatures, Tprep. A detailed understanding of the temperature-dependent synthesis and physicochemical response is required for the design of interpenetrating networks with CMC as an adsorbent that provides effective sources for the removal of azo-food dyes such as tartrazine and carmoisine from aqueous solutions. The variation of elasticity and swelling properties with respect to polymerization temperature was investigated. CMC-integration and polymerization temperature played a decisive role in the compressive elasticity. Incorporation of CMC into copolymer matrix led to a significant increase in elasticity of semi-IPNs, while mechanically weaker gels were obtained with increasing Tprep. Addition of CMC increased the swelling modulus of semi-IPNs formed at −18 °C by 2.6-fold. While the transparency changed depending on Tprep and microstructure, addition of CMC decreased the swelling rate of gels at all polymerization temperatures. The compressive modulus decreased with the swelling process in accordance with the Rubber elasticity theory. Semi-IPN gels showed stable swelling against pH-change in aqueous solutions and exhibited excellent pH-sensitivity significantly in low pH. A 4 to 12 fold decrease in maximum volume was observed by varying the pH between 2.1 and 9.8. The correlation between polymerization temperature and removal of azo-food dyes; tartrazine and carmoisine from contaminated wastewater with CMC-based gels was studied. Dynamic adsorption equilibrium was reached in 30 min, and tartrazine and carmoisine removal performances varied between 92.8 % and 98.4 %. respectively. The adsorption data for azo-dyes were evaluated by Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, Redlich-Patterson, Sips, and Tooth isotherm models, but were best described by Langmuir and Redlich-Patterson models as they gave the highest correlation. Pseudo-first order, pseudo-second order, Elovich, Avrami kinetic and intra-particle diffusion models were investigated and dye adsorption was represented by pseudo-second-order model. After the adsorption process, semi-IPNs can easily be regenerated and effectively reused over five cycles. The study provided new insights towards the facile and sustainable synthesis of eco-friendly multifunctional CMC-based gels carrying tertiary amino groups for effective removal of azo-based food colorants.

Sustainable Biological Production and Innovative Purification of the 1,3-Propanediol from Glycerol Fermentation Broth via Resin Adsorption

The study focuses on enhancing the production and purification of 1,3-Propanediol (1,3-PDO), a versatile compound used across various industries. Conventionally, 1,3-propanediol (1,3-PDO) has been derived from petroleum-based feedstocks through chemical processes, which pose significant cost and environmental concerns. This has prompted the exploration of sustainable biological production methods using microorganisms to ferment glycerol, the main by-product of palm oil transesterification in biodiesel production. However, downstream purification remains complex and inefficient. To address this, our study introduces a novel and economically viable purification strategy for 1,3-PDO derived from a semi-industrial fermentation broth. The purification process involves pre-treatment steps: centrifugation, flocculation with chitosan, decolorization with activated charcoal, and broth concentration via rotary evaporation. These steps resulted in a transparent broth with a minimal 6% loss of 1,3-PDO. Various resin types, including Sulfonated Styrene Divinylbenzene (S-SDVB) and Styrene Divinylbenzene (SDVB) ion exchange resins in different ionic forms in addition to silica gel resin, were evaluated for their effectiveness in separating 1,3-PDO in terms of recovery and purity. A key aspect of our study is the detailed investigation of the equilibrium adsorption characteristics of SDVB and S-SDVB resins, each with different ion forms. This analysis provides insights into how resin modifications affect the separation process, aiming for higher yields and purities of 1,3-PDO. The findings revealed that the Langmuir adsorption isotherm fits experimental data. Column chromatography experiments showed SDVB resins' deficiencies in separating 1,3-PDO from other components, while silica gel resin achieved a recovery rate exceeding 96% purity and approximately 80% overall recovery. Notably, the Ca2+ form of S-SDVB resin achieved high recovery (95-100%) and purity (91-93%) in both synthetic and real fermentation broths, addressing biodiesel challenges and proposing a solution for large-scale microbial 1,3-PDO production.

Assessment of three quinolin-8-ol-imidazole hybrids as corrosion carbon steel inhibitors in acidic conditions employing practical and theoretical methodologies

Three hybrids of quinolin-8-ol-imidazole were scrutinized as corrosion inhibitors in 1 M HCl for carbon steel (Cstl). These hybrids are 5-((2-(4-(dimethylamino)phenyl)-4,5-diphenyl-1H-imidazol-1-yl)methyl)quinoline-8-ol (Quin-Amino), 5-((4,5-diphenyl-2-(p-tolyl)-1H-imidazol-1-yl)methyl)quinoline-8-ol (Quin-Tolyl), and 5-((2-(4-bromophenyl)-4,5-diphenyl-1H-imidazol-1-yl)methyl)quinoline-8-ol (Quin-Br). The current research includes a mixture of methods. In addition to computational approaches, several experimental approaches were employed, such as electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM-EDX), UV-vis spectroscopy, and potentiodynamic polarization (PDP). The investigated hybrids' corrosion resistance was encountered to be concerned by the concentration, temperature, and chemical structure, which attained a maximum of 96.1% for Quin-Amino, 93.4% for Quin-Tolyl, and 92.5% for Quin-Br at 10-3M, respectively. The PDP results illustrated that the studied hybrids performed as mixed-type inhibitors. In addition, the chemisorption of these hybrids on the Cstl surface obeyed the Langmuir adsorption isotherm. SEM-EDX confirmed that the effectiveness of the three hybrids lies in their capability to develop an organic layer on the Cstl surface. The density functional theory (DFT) was employed for theoretical calculations. Molecular dynamics (MD) simulations manifest that hybrids are oriented beneficially on the Fe (110) surface, providing a high surface coverage and thus a high inhibition performance.

Impact of N-Decyl-Nicotineamide Bromide on Copper Corrosion Inhibition in Acidic Sulphate containing Environment: electrochemical and Piezoelectrochemical Insights

This work investigates the inhibition effect and adsorption properties of a new tailor-made synthesized model molecule of ionic liquids, namely N-decyl nicotinamide bromide [C10Nic]Br in an acidic 0.1 M Na2SO4 solution (pH = 2.7) against the corrosion of copper. Electrochemical methods (ac electrochemical impedance spectroscopy and dc potentiodynamic polarization), and piezoelectric method (quartz crystal microbalance with impedance analysis (EQCM-I) were applied to study the corrosion protection performance of the inhibitor. Electrochemical measurements have indicated favorable corrosion inhibition performance of [C10Nic]Br. The corrosion inhibition efficiency increases with the increase of inhibitor concentration, at a [C10Nic]Br concentration of 10-3 M the efficiency reaches 93%. The inhibitor adsorption slightly differed from the ideal Langmuir adsorption isotherm. [C10Nic]Br can be considered to be a mixed-type inhibitor. The inhibition efficiency was found to be time-dependent. In the presence of the highest 10-3 M inhibitor concentration the formation of the maximum protective effect of the inhibitor layer takes several hours, the maximum value of polarization resistance was 8.5 kΩ.cm2 after 5 hours. The copper dissolution and the inhibitor adsorption were also monitored by real-time changes in mass and viscoelasticity determined by QCM-I. It was obtained that the inhibitor adsorption on the copper surface leads to a decrease in copper dissolution and an increase in viscoelasticity. The layer on the copper surface becomes softer due to the complex between the inhibitor and the corrosion products on the surface.

Adsorption behavior and mechanism of lead by starch/tobermorite composite hydrogel.

Tobermorite (TOB) is a synthetic inorganic mineral material with a montmorillonite-like layered structure that removes heavy metals from water, and its incorporation into starch-based hydrogels can optimize the stability and adsorption properties of the hydrogels; it can also significantly reduce the storage pressure of fly ash (FA) and reduce environmental pollution. This study utilized starch/tobemolite/acrylic acid (LR/TOB/AA) as the raw material, successfully synthesizing a starch-tobemolite composite hydrogel (LR-TOB/AA) using aqueous solution polymerization. The hydrogel exhibits excellent water absorption and retention capabilities, as well as a significant adsorption effect on Pb(II). The influence of adsorption duration, starting concentration, temperature, and hydrogel incorporation on Pb(II) adsorption was examined by intermittent adsorption experiments. The maximal adsorption capacity of Pb(II) was 900.25 mg/g, surpassing the majority of reported hydrogel adsorbents, as determined by Langmuir isothermal adsorption model fitting. Following five adsorption-desorption cycles, the hydrogel's adsorption of Pb(II) persisted above 90 %.

Magnetic bentonite with organic modification highly efficient for adsorption of Ce(III) and Y(III)

A simple organic magnetic adsorbent (PAA-MBent) was synthesized using 2-hydroxyphosphonylacetic acid and applied to the adsorption of Ce(III) and Y(III). It was confirmed that the phosphoryl groups could effectively regulate the homogeneous loading of magnetic particles on the bentonite during the synthesis process, and the hydroxyl and phosphoryl groups can be sufficiently used on the surface of bentonite to increase the abundance of adsorption sites, which have favorable coordination with Ce(III) and Y(III). The experimental results showed that the maximal adsorption capacity was increased to 99.11 mg/g and 65.65 mg/g for Ce(III) and Y(III), respectively, which was 2.52 and 2.91 times higher than magnetic bentonite. The adsorption behavior conformed to the Langmuir isothermal adsorption model and the pseudo-second-order kinetic model, and the adsorption of Ce(III) by PAA-MBent performed better than that of Y(III). The adsorption efficiency was affected by ionic strength and site inhibition of coexisting cations, and its adsorption selectivity was mainly disturbed by the competition of Al ions. The results after adsorption identified the key adsorption mechanisms as ion exchange, electrostatic attraction, functional group complexation, and hole filling. After five cycles, the adsorbent still exhibited good adsorption and magnetic recovery performance. These results reveal that PAA-MBent is promised to be a novel, inexpensive and effective adsorbent for the removal of Ce(III) and Y(III) from contaminated water.

Efficient multifunctional PPy-NTs/PEI@alginate@NiFe2O4 magnetic beads for heavy metals removal: Experimental design and optimization interpretations

A highly effective magnetic nanocomposite alginate beads (PPy-NTs/PEI@Alg@NiFe2O4) were synthesized using alginate as the encapsulation reagent and polypyrrole/polyethylene imine with nano NiFe2O4 as a functional filler to remove toxic Zn2+ and Pb2+ from polluted water. A response surface methodology (RSM) was used to statistically assess the influences of pH and the adsorbent dose on the adsorption performance. PPy-NTs/PEI@Alg@NiFe2O4 magnetic microbeads exhibited the optimal adsorption capacity qe (18.6 mg/g) at pH 6 and a 2 mg/L dose for Zn2+ removal. In comparison, the optimal qe (32.6 mg/g) was reached at pH 4.5 with a 1.5 mg/L dose for Pb2+ remediation. From batch experiments, maximal absorption capacities of 53.3 mg/g and 22 mg/g were achieved for Pb2+ and Zn2+, respectively, at 313 K. The pseudo-second-order kinetic model fitted the results well, suggesting that the chemisorption process regulates adsorption. Isotherm models indicate the presence of homogeneous adsorption sites from the well-fitting to Langmuir isotherm. An investigation of the effects of temperature and thermodynamic considerations revealed the endothermic nature of Zn2+ and Pb2+ absorption. The Fourier transform infrared spectra showed that –NH, –NH2, and –COO− are the main groups in PPy-NTs/PEI@Alg@NiFe2O4 composite beads that were responsible for Zn2+ and Pb2+ removal from polluted water.

Adsorption and removal of Pb (II) via layer double hydroxide encapsulated with chitosan; synthesis, characterization adsorption isotherms, kinetics, thermodynamics, & optimization via Box-Behnken design

The study aimed to enhance the stability and efficiency of removing bivalent Pb(II) by encapsulating AlNi-layered double hydroxide (LDH) in chitosan and itaconic acid to create an adsorbent with chemically active sites. The resulting material, AlNi-LDH/CS, underwent thorough property analysis using XRD, FT-IR, XPS, EDX, N2 adsorption/desorption isotherm, and FESEM to find out what textural characteristics it has. Specifically, nitrogen adsorption/desorption isotherms were utilized to assess the textural properties of AlNi-LDH/CS. The Al/Ni-LDH/CS surface displayed a specific surface area of 71.95 m2/g and an average pore size of 2.537 nm, consistent with the platelets' external surface. The effects of dose, pH, temperature, and starting concentration on the adsorption process were also investigated in this study. The adsorption characteristics have been examined by means of equilibrium and adsorption kinetics. The adsorption process adhered to the pseudo-second-order and Langmuir isotherm models. The predominant adsorption process was found to be chemisorption, which had an adsorption energy of 28.42 kJ·mol−1. An endothermic and spontaneous adsorption process is suggested by the increase in metal absorption at increasing temperatures. The Box-Behnken design software was utilized to establish the optimal adsorption parameters as pH 5, a dosage of 0.2 g of AlNi-LDH/CS per 25 mL, and an adsorption capacity of 453.05 mg/g for the Pb(II) arsenate solution. For the composite sponge to be most effective in adsorbing arsenate and be used in water purification procedures, these factors are essential. The adsorption process was successfully improved with few planned tests by applying the Box-Behnken design and response surface technique aspects of the Design-Expert software. An evaluation of the adsorbent's reusability using six successive cycles of adsorption and desorption confirmed its stability and showed no discernible decrease in removal efficiency. Additionally, it retained its original chemical composition before and after reuse, showcased consistent efficiency, and maintained uniform XRD data.

Equilibrium loadings and adsorption isotherm model parameters estimated from multi-component breakthrough curves

Quantitative knowledge of competitive adsorption isotherms is essential for the design and optimization of adsorption based separation processes. Since the experimental determination of these thermodynamic functions is complicated and time consuming, there is a need for fast and easy to apply methods. In particular attractive are methods that evaluate measured breakthrough curves (BTC). Key features of these curves can be predicted with the equilibrium theory, which ignores kinetic effects that cause band broadening. If the adsorption equilibria can be described by the classical competitive Langmuir isotherm model, outlet concentration profiles can be calculated analytically. The paper summarizes and illustrates well-known classical results for N-component systems. The theory is applied to analyze experimentally determined BTC for a ternary mixture fed into an initially fully regenerated column under constant flowrate and under isothermal conditions. It is demonstrated that the retention times and intermediate plateau concentrations, which are observable for example in a single ternary BTC experiment, allow estimating a defined number of characteristic equilibrium loadings. These loadings can be directly used for easy estimation of the parameters of an assumed isotherm model. Various possibilities to use a reduced number of loadings and to include complementary results of standard pulse experiments are described. The isotherms generated from the ternary BTC are successfully validated by results of single component and ternary BTC experiments carried out subsequently. Options to generalize the method to determine isotherm model parameters from measured BTC to initially preloaded columns and to more complex mixtures are finally outlined.

Polymeric Adsorbent for the Effective Removal of Toxic Dyes from Aqueous Solutions: Equilibrium, Kinetic, and Thermodynamic Modeling

AbstractThis study investigates the adsorption behavior of anionic (Congo red, Eosin yellow) and cationic (Malachite green) dyes on synthesized TD polymer particles, highlighting the material's potential as an effective adsorbent for industrial wastewater treatment. Key operational parameters, including initial solution's pH, contact time, initial dye concentration, and temperature, were systematically evaluated to determine their influence on adsorption efficiency. The experimental data demonstrated that the Langmuir isotherm provided the best fit for all three dyes, indicating monolayer adsorption with maximum adsorption capacities of 153.8 mg/g for Malachite green, 49.36 mg/g for Congo red, and 227.9 mg/g for Eosin yellow. Kinetic analysis revealed that the adsorption of Malachite green and Congo red followed pseudo‐second‐order kinetics, while Eosin yellow adsorption was better described by the intra‐particle diffusion model. Thermodynamic assessments, including Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°), confirmed the spontaneous and endothermic nature of the adsorption processes for Malachite green and Eosin yellow, contrasting with the exothermic behavior observed for Congo red. These findings underscore the versatility and effectiveness of TD polymer particles in removing both anionic and cationic dyes from aqueous solutions. Further research could explore material optimization and real‐world applications to broaden their utility in sustainable water treatment strategies.

Development of Luminescent and Photosensitive Cellulose Microfibers From Palm Sprout Fibers: Antibacterial Efficacy and Dye Adsorption Potential.

A key contemporary challenge is enhancing the value of agro-industrial byproducts. Cellulose, the most abundant renewable resource, offers significant industrial potential due to its versatile properties. Produced in its pure form by various bacteria, cellulose is increasingly utilized in microscale and nanoscale fibers for composite reinforcement. In this study, cellulose microfibers were derived from palm sprout fibers through a series of treatments like pretreatment, high-pressure hydrolysis in an autoclave, and bleaching. These fibers were then characterized using techniques such as UV spectroscopy, FTIR, SEM, and XRD. The study evaluated the antibacterial properties of the treated cellulose microfibers against both gram-positive Staphylococcus aureus (07%) and gram-negative Escherichia coli (10%), finding higher effectiveness against E.coli. Additionally, the microfibers exhibited a lower EC50 value of 0.101 mg/mL, suggesting that although the microfiber extract is effective, the standard antioxidant is somewhat more potent. Adsorption studies revealed that the cellulose microfibers followed the Langmuir isotherm model, with a high determination coefficient of 0.998, and reached maximum dye adsorption for RB 160 within 120 min. In this adsorption study, 50 mg of dye was removed. These results indicate that the treated cellulose microfibers are a promising biosorbent for improving dye removal processes.

Efficient Adsorptive Removal of Levofloxacin Using Sulfonated Graphene Oxide: Adsorption Behavior, Kinetics, and Thermodynamics

Water pollution by antibiotic residues poses a potential threat to environmental and human health. Graphene-based materials are highly stable, recyclable and effective adsorbents for efficiently removing antibiotics from polluted water. In this study, the adsorption behavior of levofloxacin onto sulfonated graphene oxide (SGO) was investigated by varying the contact period, solution pH, adsorbent quantity, levofloxacin concentration, inorganic ions, and solution temperature. Spectroscopic and microscopic techniques were employed to confirm the adsorptive interaction between levofloxacin and SGO. The adsorption process was most accurately characterized by the pseudo-second-order kinetic model and the Langmuir isotherm model, as indicated by their high correlation coefficients (R2) and low root-mean-square error (RMSE) values. The maximal quantity of levofloxacin that can be adsorbed onto SGO was determined to be 1250 μmol/g at pH 4 and 25 °C using the Langmuir model. Thermodynamic studies reveal that the process of levofloxacin adsorption onto SGO is endothermic and spontaneous in nature. Taking into consideration the results of adsorption, desorption and regeneration studies, it is proposed that SGO can be applied as an economic viable agent for the adsorptive removal of levofloxacin from the aqueous environment.

Synthesis of MOF@COF composites and study on dye adsorption properties

MOF@COF hybrid materials not only have high stability and adjustable function, but also have the characteristics of MOFs and COFs materials, which make them have important application value in the field of adsorption. This article employs 1,3,5-benzene tricarbonyl chloride and p-Phenylenediamine as covalent organic framework monomers. Through the in-situ growth of covalent organic frameworks (COF) on the surface of NH2-MIL-88(Fe) material, a novel, stable, and porous COF-on-MOF hybrid material (NH2-MIL-88(Fe)/COF) was synthesized. The structure, morphology, and performance of the hybrid material were thoroughly examined using characterization techniques, including Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). Subsequently, We explored the MOF@COF hybrid material as an effective adsorbent for removing organic dyes, namely methylene blue (MB), methyl orange (MO), and crystal violet (CV). The influence of various adsorption parameters, such as adsorption time, initial dye concentration, and different pH values, on dye adsorption performance was systematically investigated. Experimental results revealed that at pH = 7, NH2-MIL-88(Fe)/COF demonstrates maximum adsorption capacities of 114 mg·g−1, 106 mg·g−1, and 102 mg·g−1 for methylene blue, methyl orange, and crystal violet, respectively. The adsorption process follows pseudo-second-order kinetics and Langmuir isotherm models. Lastly, NH2-MIL-88(Fe)/COF maintains high removal efficiency for the three dyes even after five repeated uses, establishing it as a stable and efficient adsorbent. The research findings suggest that MOF@COF hybrid materials hold promising applications in the treatment of dye-containing wastewater.

Colorimetric and fluorometric sensing of polar E120 in juice and environmental water samples using mannitol-functionalized magnetic nanoparticles and nitrogen-doped carbon dots

In this study, mannitol-functionalized magnetic nanoparticles (MMNPs) as a unique nanosorbent and N-doped fluorescent carbon dots (N-CDs) as a cost-effective nanosensor were created and utilized, for the first time, for dispersive micro-solid-phase extraction (Dµ-SPE) to determine carmine (E120) dye in water samples and juices. The modification of the magnetic nanoparticles with mannitol was designed to enhance the responsive potential for adsorption of the polar E120 dye from complex sample matrices through electrostatic interaction. The as-fabricated N-CDs fluorescent probe exhibited a high fluorescence quantum yield (Φs) of 43.1 %, allowing for accurate fluorometric detection of E120 dye. The as-synthesized MMNPs nanosorbent and fluorescent N-CDs nanoprobe were characterized by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Transmission electron microscopy (TEM), Energy Dispersive X-ray (EDX), Thermogravimetric analysis (TGA), and Vibrating-sample magnetometer (VSM). Density Functional Theory (DFT) studied the E120 dye structure using Gaussian 09 to explore the interactions between E 120 dye molecules and MMNPs/N-CDs. The impact of the critical adsorption and detection experimental factors was investigated and adjusted. A minimal amount of MMNPs nanosorbent (150 mg) is sufficient for E120 extraction in an acceptable time of 15 min. Furthermore, with a high determination coefficient, the adsorption characteristics fit with the models of Langmuir isotherm and first-order kinetics. The adsorption capacity (qe) of the as-fabricated MMNPs was 87.7 mg.g−1. After adsorption, E120 dye was fluorometrically analyzed using nitrogen-doped carbon dots as a fluorescent nanosensor via the inner filter effect (IFE) mechanism. Under the optimized conditions, the proposed fluorometric procedures showed a linear increase in the fluorescence ratio with increasing the E120 concentration in the range of 1.0 – 160.0 μg.mL−1 with detection (LOD) and quantitation (LOQ) limits of 0.27 and 0.83 μg.mL−1, respectively. The relative standard deviation (%RSD) did not exceed 2.34 %. The proposed methodology was successfully applied to determine E120 dye in juice and environmental water samples with % recovery ranged from 89.2-106.1 % and 92.9–107.2 %, respectively offering a reliable and environmentally friendly alternative to traditional detection methods with potential applications across various industries.