Langmuir Isotherm Model Research Articles

Adsorptive removal of carcinogenic azo dye from aqueous solution using NaCPT@HDTMA

ABSTRACT This study investigated the effectiveness of the clinoptilolite (Na@CPT) surface as an adsorbent for removing anionic dyes. The Na@CPT surface was modified using hexadecyltrimethylammonium bromide (NaCPT@HDTMA) to improve its ability to remove Reactive Blue 171 (RB171) from water. A thorough study was conducted to analyze the adsorption isotherms, kinetics, temperature, and pH effects of RB171 onto Na@CPT and NaCPT@HDTMA. A pH of 1.0 was found to be the optimum value for adsorbents. Kinetic studies revealed that both adsorbents followed the pseudo-second-order kinetic model, with NaCPT@HDTMA exhibiting a faster adsorption process and quickly reaching equilibrium with increasing temperature. The adsorption efficiency of RB171 was found to improve by 83.56% after the modification at 50°C. The equilibrium data showed that the adsorption of RB171 on Na@CPT and NaCPT@HDTMA fit the Freundlich and Langmuir isotherm models, respectively. The thermodynamic parameters showed that the overall adsorption process of both adsorbents was endothermic and spontaneous. NaCPT@HDTMA is a highly effective adsorbent for removing RB171 from aqueous solution due to its low cost and abundant presence in nature.

Efficient separation of cerium from rare earth elements and major impurities using low cost manganese ferrites from highly acidic solutions

Sorption of REEs using spinel-ferrite nanoparticles has received great attention in the last decades, because of combining the advantages of iron and manganese metal oxides. Nano-manganese ferrite (MnFe2O4) was successfully synthesized using the co-precipitation method and modified with the addition of zinc to produce (Mn0.8Zn0.2Fe2O4). The synthesized materials were characterized using FTIR, SEM with EDX-mapping, XRD, chemical stability, and surface area. Several process parameters were studied to optimize the efficiency of Ce(III) separation from La(III), Eu(III), Pb(II), and Fe(III) from highly acidic media. The parameters include contact time, solution pH, and metal ion concentration. The sorption process was well fitted to the pseudo-2nd order model, which confirms the chemical nature of the sorption process where equilibrium was achieved after 30 minutes. The pH study's findings demonstrate that Ce(III) was most effectively separated at a very high, acidic pH of 0.5. Both MnFe2O4 and Mn0.8Zn0.2Fe2O4 have high chemical stability in different media where the weight loss was less than 10 %. The correlation coefficient and residual errors analysis confirm that the non-linear extended sips isotherm model more accurately expresses the behavior of the sorption process than the non-linear Freundlich and Langmuir isotherm models. The modified material Mn0.8 Zn0.2Fe2O4 shows higher sorption capacities for all the studied metal ions than MnFe2O4. The maximum sorption capacities of Ce(III), La(III), Eu(III), Pb(II), and Fe(III) in the mixture were 59.2, 6.5, 6.3, 15.4, and 13.7 mg/g, respectively.

Novel carboxymethyl cellulose-based hydrogel embedded with metal organic framework for efficient cationic dye removal from water

The rGO/CMC/β-CD (RCβ) hydrogel was synthesized from reduced graphene oxide (rGO), β-cyclodextrin (β-CD) and sodium carboxymethyl cellulose (CMC) by radical polymerization. A novel hydrogel adsorbent was created by growing the metal-organic framework (Cu-BTC) in-situ on RCβ hydrogel, which has excellent adsorption capacities for cationic dyes in wastewater. The adsorption parameters such as the amount of adsorbent, pH of solution and adsorption time were optimized through batch adsorption experiments. Under the optimal conditions of pH 6.0, adsorbent dosage of 0.01 g and experimental temperature of 25 °C, Langmuir isothermal model was used to fit the maximum adsorption capacities of methylene blue (MB), crystal violet (CV) and malachite green (MG), which were 892.66, 842.75 and 633.77 mg g−1, respectively. The fitting results of adsorption kinetics revealed that the pseudo-second-order model can describe the adsorption process better. Based on proposed studies, the dye molecules were adsorbed onto RCβ@Cu-BTC hydrogel mainly through electrostatic interaction, hydrogen bonding and π–π interactions. After five cycles, the adsorption efficiency of the RCβ@Cu-BTC hydrogel for MB, CV and MG can still reach 80 %, 77 % and 72 %, which shows that the adsorbent has good adsorption performance. Various adsorption experiments shows that RCβ@Cu-BTC hydrogel has great potential in treating dye wastewater.

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.

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.

Adsorptive removal of ppb levels of boron trichloride using N-doped porous carbon materials

The removal of trace boron impurities (BCl3) in chlorosilane represents a significant challenge in polysilicon production. In this study, we employed the high-temperature ammonia etching method to fabricate nitrogen-doped porous carbon (NPC) adsorbents derived from lignite. The as-prepared NPCs were tested and evaluated as potential adsorbents for efficient removal of BCl3. Furthermore, a systematic investigation was conducted to assess the impact of contact time, initial concentration, adsorbent dose, and temperature. It was found that the adsorbent (NPC900) obtained at 900 °C exhibited an excellent efficacy in removing BCl3 (R% = 98.9 %), with a residual concentration of BCl3 in the solution was 1.65 ppb, which met the industrial requirements. This can be primarily attributed to its porous structure and high pyridinic-N content. Furthermore, the adsorption of BCl3 on NPC900 was better followed by Pseudo-second order kinetic model and the Langmuir isotherm model. Thermodynamic studies showed that the adsorption process was spontaneous and exothermic. The interactions between BCl3 and different nitrogen forms was analysis through the utilizing density functional theory (DFT) calculation. The findings indicate that pyridinic-N exhibits a stronger interaction with BCl3 (Eads = −102.35 kJ/mol), primarily due to the easier electron transfer from the nitrogen atom on pyridinic-N to BCl3.

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.

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 %.

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.

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.

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.

Advanced Polymer Composites for Effective Removal of Perfluorooctanoic Acid (PFOA) Pollutants From Aqueous Solutions.

Perfluorooctanoic acid (PFOA) is extensively utilized in industrial applications, posing significant environmental and health risks because of its persistence and toxicity. Effective elimination methods are vital to mitigate its adverse effects on ecosystems and human health. In this study, we investigate the potential of biomass-derived polymer composite for PFOA adsorption in aqueous solution. Due to its unique surface interaction and porosity, the polymer-based composite derived from sustainable biomass sources exhibits favorable adsorption characteristics. The physicochemical properties of polymer composites were characterized using FTIR, XRD, SEM-EDS, XPS, and BET analysis. The polymer composites reached a maximum PFOA adsorption efficiency about 93.3% under optimized conditions determined by Box Behnken Design. The Langmuir isotherm model revealed and provided an adsorption capacity of PFOA about 13.98 mg g-1. Moreover, the polymer-based composites demonstrated reusability, with removal rates of PFOA ranging from 93.3% to 52% over the course of four cycles after desorption. Our findings underscore the possibility of biomass-derived polymer composites as long-term and effective adsorbents for PFOA removal from aqueous environments.

Effective adsorptive removal of heavy metal anion Cr(Ⅵ) and dye cation methylene blue by the novel 2D material TiVCTx MXene

With the increasingly serious industrial pollution, the effective removal of heavy metal ions and organic pollutants from wastewater has become a key issue of environmental protection. In this paper, a new MXene material, TiVCTx, was prepared by in situ etching, and its adsorption capacity of heavy metal anion Cr(Ⅵ) and methylene blue (MB) dye cation was studied. The effect of adsorption time, pH values, temperatures, initial concentrations of adsorbent and adsorbate, interfering ions on the Cr(Ⅵ) and MB adsorption of TiVCTx was systematically investigated. It is found that TiVCTx has excellent Cr(Ⅵ) and MB adsorption property, the adsorption capacity can be as high as 600mg/g and 1430mg/g, respectively. The adsorption experiments revealed that the adsorption process of Cr(Ⅵ) conformed to the Langmuir isotherm model and the Pseudo-second-order kinetic model, which indicated that the Cr(Ⅵ) adsorption was a heat-absorbing monolayer chemisorption. In contrast, the adsorption process of MB is in accordance with the Freundlich isotherm model and the Pseudo-second-order kinetic model, suggesting that the MB adsorption was an exothermic multilayer chemisorption. The results of X-ray electron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) analysis further confirmed that the reductive adsorption and electrostatic adsorption can account for the outstanding Cr(VI) and MB adsorption capacity of TiVCTx, respectively.

Adsorption Isotherm, Kinetic and Thermodynamic Studies for Removal of Fluoride Ions from Drinking Water Using Modified Natural Pumice

This study aimed to modify pumice using aluminum chloride as an adsorbent for defluoridation. Batch and column experiments were carried out to evaluate the effects of pH, initial fluoride concentration, contact time, dose, and temperatur. The modified pumice adsorbent showed good fluoride removal in both batch and column studies. Fluoride up-take was observed to be effective >7%, at pH 6.5-7.5, and adsorption equilibrium time was observed at 60 min. the adsorption results were modelled using kinetic and isotherm models. Experimental data indicated that fluoride adsorption follows the second pseudo-order kinetics model (R2 > 0.99) and fits well with both the Freundlich and Langmuir isotherm models, which showed favorability for the adsorption of fluoride with a maximum capacity of 0.083 mg/g. The negative values of ∆Ho and ∆Go indicate that the adsorption process was feasible, exothermic, and spontaneous. The column performance showed the best fluoride uptake efficiency, with a breakthrough capacity of 0.48 mg/g. The %R was approximately %100 using0.1M NaOH. Fluoride levels in real wells water decreased dramatically (e.g. 4.1-0.88, 7.1-1.54, and 6.2-1.46 mg/L). The results revealed that modified pumice has the potential for fluoride removal from drinking water.

Good adsorption performance for both cationic and anionic dyes by a novel crosslinked tetrafluoroterephthalonitrile-tannic acid-chitosan polymer synthesized via one-pot reaction

In this work, tetrafluorophenonitrile was utilized to crosslink tannic acid and chitosan together to form a new crosslinked polymer (CSTTA), and then the Fe3O4 nanoparticles were prepared and immortalized on the CSTTA at the same time to obtain the Fe3O4/CSTTA composite. The structures of CSTTA polymer and Fe3O4/CSTTA composite were characterized by SEM, FTIR, TGA, 13CNMR, XPS, WAXD, N2 adsorption-desorption isotherm, VSM, and zeta potential measurement. The CSTTA could simultaneously adsorb the cationic methylene blue (MB) and anionic orange G (OG), and its adsorption behaviors for MB and OG conformed to the pseudo-second-order kinetic model and the Langmuir isotherm model, which were spontaneous according to thermodynamic calculation. The CSTTA possessed not only high adsorption capacities for both MB and OG up to 1092.69 mg/g and 519.89 mg/g at 303 K under the optimal pH conditions of pH=10 and pH=1, respectively, but also the good reused ability. In addition, the Fe3O4/CSTTA composite could also absorb both MB and OG with good magnetically recollected ability to avoid secondary pollution.

A sustainable lignin-clay nano-absorbent for highly efficient methylene blue removal

Water pollution caused by toxic dyes such as methylene blue (MB) has become a bottleneck for recycling or reusing enormous industrial wastewater. Designing a green and cost-effective bio-absorbent for the highly efficient removal of MB from wastewater is crucial but remains a great challenge. In this study, abundant, inexpensive, and environmentally benign lignin and bentonite were used as starting materials, and quaternary and amphiphilic lignin as a network macromolecule was designed to be inserted into the galleries of the stacked bentonite clay to prepare lignin-bentonite nanohybrids. The specific surface area of the modified nano-absorbent was significantly increased to 45.60 m2/g and owned a type II-like isothermal mechanism. The absorbent showed a maximum removal of MB of 99.7 % at neutral pH and room temperature with a maximum adsorption capacity of 822.22 mg/g, demonstrating the potential of an excellent adsorbent. The MB adsorption process fits well with both Langmuir and Freundlich isotherm models, the adsorption mechanism includes strong electrostatic attraction between absorbent and MB, and physical adsorption in a complicated monolayer and multiple macroporous structures. This study leverages the economic and environmental benefits of lignin and bentonite clay to prepare a cost-effective bio-absorbent for efficient removal of MB from aqueous solutions.

Synthesis, characterization and study of Sb(Ⅲ) adsorption from aqueous solution by iron-aluminum pillared attapulgite

In this study, a simple, environmentally friendly and inexpensive adsorbent for Sb(III) in aqueous solution was prepared by the copolymerization method using attapulgite as the matrix, FeCl3 and AlCl3 as the metal sources. The morphology and structure of iron-aluminum pillared attapulgite were analyzed through various characterization methods. The conditions and influencing factors of iron-aluminum pillared attapulgite preparation and Sb(III) adsorption were studied. The saturated adsorption capacity of Sb(III) could reach 60.44 mg·g−1 for 180 min at pH 7 and 298 K. The adsorption process is conformed to Langmuir isothermal model and pseudo-second-order kinetic model, and the thermodynamic investigation suggested a spontaneous and endothermic adsorption process. It was revealed by X-ray photoelectron spectroscopy analysis and Zeta potential analysis that Sb(III) was first electrostatically adsorbed by the adsorbent, part of Sb(III) was oxidized to Sb(V) by Fe(III) and then antimony was complexed with iron and aluminum hydroxides to form surface complexes. In addition, a small amount of antimony migrated through intra-particle diffusion into the internal micropores and reacted with hydroxyl groups. Most coexisting components under the chosen conditions had no influence on Sb(III) adsorption, and PO43−, AsO33−, C6H8O7 and H2C2O4 had a negligible effect. However, the adsorption capacity of over 90 % without interference showed that the material has a strong selectivity for Sb(III) adsorption. The findings of the desorption experiment showed that the adsorption product has a considerable degree of desorption at increased hydrochloric acid concentrations. It may be concluded that the adsorption product is more stable in the overall polluted water environment since the actual acidity of the polluted water environment is significantly lower than the desorption experiment acidity. Overall, iron-aluminum pillared attapulgite has great potential for application in removing Sb(III).

Silica/klucel nanocomposite as promising durable adsorbent for lead removal from industrial effluents

The removal of heavy metals, such as lead, from industrial wastewater is imperative due to their detrimental effects on both human health and the environment. This study delves into investigating the feasibility of employing a novel adsorbent, specifically a silica/klucel nanocomposite, for effectively extract lead from industrial effluents. The synthesis of this nanocomposite involved a simple and cost-effective method, combining silica nanoparticles with klucel. XRD, FTIR, E-SEM, Raman, and N2 gas adsorption at − 196 °C tools were employed to prospect the formation of silica/klucel nanocomposite. Outstandingly, treating 50 ml of 50 mg/l of lead with 10 mg of adsorbent exhibited rapid removal, which reached a maximum (95%) at 60 min contact time. The resulting composite demonstrated remarkable adsorption capabilities, primarily attributed to two factors: the expansive surface area of silica nanoparticles 139.1 m2/g and the porous structure provided by klucel. Through batch adsorption experiments, the nanocomposite’s proficiency in removing lead ions from aqueous solutions became evident. The kinetics of the adsorption process were found to adhere closely to a pseudo-second-order model, hinting at chemical adsorption as the rate-determining step. Langmuir isotherm model revealed that lead ions tend to form a monolayer on the surface of the nanocomposite and the maximum adsorption capacity (qm) was 63.938 mg/g. Additionally, the nanocomposite, exhibited notable stability and could be reused multiple times, where 65% removal efficiency was announced until the 7th cycle without significant degradation in performance. In summary, the silica/klucel nanocomposite emerges as a promising and eco-friendly adsorbent for removing lead from industrial effluents. Its efficient performance and sustainability offer a compelling solution to combat heavy metal contamination, thereby contributing to environmental preservation and human well-being.