Maximum Adsorption Research Articles

High-performance removal of methylene blue dye using porous lignin extracted from sugarcane bagasse by deep eutectic solvent

This study evaluated the ability of triethyl benzyl ammonium chloride/lactic acid deep eutectic solvent extracted lignin (TEBAC/LA-DES-L) to adsorb methylene blue (MB) without additional functional group modification. The structure and morphology of TEBAC/LA-DES-L were characterized using SEM, BET, FT-IR, and TGA techniques. Various factors influencing MB adsorption, such as extraction temperature, solution pH, adsorbent dose, initial MB concentration, adsorption time, and reaction temperature, were investigated. The Redlich-Peterson isotherm displayed a good fit for the experimental data, with a maximum adsorption capacity of 85.16 mg/g. Kinetic analysis suggested that the adsorption process followed the pseudo-second-order model, with adsorption occurring in <100 min on DES-L-4 h. The mechanism of MB adsorption on DES-L-4 h was attributed to electrostatic attraction, hydrophobic interactions, and hydrogen bonding forces. Overall, DES-L-4 h demonstrated high adsorption capacity and rapid adsorption rate, making it a promising adsorbent for effectively removing cationic dyes from wastewater.

Investigate Performance of ATGF nanocomposite based on guar gum polymer for adsorption of Congo Red dye and alpha lipoic acid drug from wastewater: study kinetics and simulation

AbstractIn this study, the synthesized nanocomposite novel arginine/thiourea/guar gum/ferrite (ATGF) adsorbent was evaluated for the adsorption of alpha lipoic acid (ALA) and Congo Red (CR) from wastewater. The synthesized nanocomposite was examined by Brunauer–Emmett–Teller theory (BET), Termal gravimetric analysis (TGA), Fourier transform infrared spectrometer (FT‐IR), field emission scanning electron microscopy (FE‐SEM), X‐ray Diffraction (XRD), Vibrating sample magnetometer (VSM), and energy dispersive X‐ray (EDX). For the removal of ALA and CR from aqueous solution, the capacity of the nanocomposite was investigated by working on a series of experiments such as the effect of adsorbent dose, initial concentration, contact time, pH and temperature. The adsorption kinetics of these two pollutants were investigated using pseudo‐first‐order and pseudo‐second‐order velocity equations. The nanocomposite kinetics follow pseudo‐second‐order. Langmuir and Freundlich isotherms were investigated. The results show that the Langmuir isotherm model gives the maximum adsorption capacity of ALA as 96.93 mg g−1 and of CR as 229.34 mg g−1 on the nanocomposite. © 2024 Society of Chemical Industry.

Nano-Hydroxyapatite Modified Tobacco Stalk-Based Biochar for Immobilizing Cd(II): Interfacial Adsorption Behavior and Mechanisms

Biochar, an eco-friendly, porous carbon-rich material, is widely studied for immobilizing heavy metals in contaminated environments. This study prepared tobacco stalks, a typical agricultural waste, into biochar (TSB) modified by hydroxyapatite (HAP) at co-pyrolysis temperatures of 350 °C and 550 °C to explore its Cd(II) adsorption behavior and relevant mechanisms. XRD, SEM–EDS, FTIR, and BET analyses revealed that HAP successfully incorporated onto TSB, enriching the surface oxygen-containing functional groups (P–O and carboxyl), and contributing to the enhancement of the specific surface area from 2.52 (TSB350) and 3.63 m2/g (TSB550) to 14.07 (HAP–TSB350) and 18.36 m2/g (HAP–TSB550). The kinetics of Cd(II) adsorption onto TSB and HAP–TSB is well described by the pseudo-second-order model. Isotherm results revealed that the maximum adsorption capacities of Cd(II) on HAP–TSB350 and HAP–TSB550 were approximately 13.17 and 14.50 mg/g, 2.67 and 9.24 times those of TSB350 and TSB550, respectively. The Cd(II) adsorption amounts on TSBs and HAP–TSBs increased significantly with increasing pH, especially in HAP–TSB550. Ionic strength effects and XPS analysis showed that Cd(II) adsorption onto HAP–TSBs occurred mainly via electrostatic interaction, cation exchange with Ca2+, complexation with P–O and –COOH, and surface precipitation. These findings will provide a modification strategy for the reutilization of tobacco agricultural waste in the remediation of heavy metal contaminated areas.

Synthesis of composites from coal gasification slag by acid leaching and NaOH activation for efficient adsorption of methylene blue

This study successfully developed a carbon-silicon composite material (C-Si@GS) by acid leaching (HCl) and alkali activation (NaOH) treatments from solid waste CGS and applied to the adsorption of methylene blue (MB). The effects of material dosage, pH, contact time, initial concentration and co-existing ions on the removal of MB were investigated. The results revealed C-Si@GS had good adsorption performance at different pH and cations, suggesting that the material had stable properties. The adsorption of MB by C-Si@GS reached the equilibrium within 12 h, and the removal rate was up to 99 %. The maximum adsorption capacity of C-Si@GS was 456.8 mg/g calculated by Langmuir model (C0 (MB) = 120 mg/L, pH=7 ± 0.2, dosage = 0.6 g/L, and T=298 K). The adsorption process is consistent with Pseudo-secondary and Freundlich models, suggesting that both physical and chemical adsorption processes coexist. Adsorption mechanisms are mainly van der Waals forces, hydrogen bonding, electrostatic attraction and π-π bond interaction, as analyzed by XPS and FT-IR. The composites were regenerated using HCl as desorption agent and the removal rate was about 50 % after 3 cycles. The results illustrated that C-Si@GS can serve as an effective adsorbent for removing MB.

Highly porous carbon with rich inherent groups for ultrahigh adsorption of organic dyes from wastewater

Activated carbon from renewable biomass or its waste to purify various dyeing wastewater from textile industry is highly desired. In this work, porous activated carbon was prepared by using silk waste as precursor via a simple one-step carbonization process. The obtained SWC-1-800 had ultrahigh adsorption for anionic dye AR73 and cationic dye MB owing to its ultrahigh specific surface area (2774 m2 g−1) and rich functional groups. SWC-1-800 had an increased adsorption capacity reaching 1310 and 928 mg g−1 for AR73 and MB respectively as the initial concentration up to 1000 mg L−1. Moreover, the adsorption capacity was stable under a wide range of Na+ and SDS concentration. By adjusting the temperature and pH value, the maximum adsorption capacity reached 1337 and 1000 mg g−1 for AR73 and MB respectively, keeping the removal rate of AR73 and MB more than 80 % after 5 adsorption cycles. Besides, SWC-1-800 demonstrated quite good adsorption ability for many other kinds of dyes, which adsorption capacity as high as 1998 mg g−1 (Rh B). The adsorption mechanism was further proposed according to the structural characteristics, inherent functional groups and adsorption properties. Using silk waste-derived carbon to effectively absorb the harmful dyes in the wastewater shows dual value for cleaner production via a “waste-waste to clean products” model, which has great application potential in dyeing wastewater purification.

Purification of mercury in Ciujung River water, Banten province, Indonesia by adsorption method using Fe3O4 nanoparticles

The Ciujung River, one of the main rivers in Banten province, Indonesia, plays an important role in agriculture and sanitation. However, the increasing use of heavy metals, especially mercury, by industries along the Ciujung River has caused significant environmental pollution. This issue requires considerable attention to ensure that environmental problems can be resolved immediately. This study evaluated the feasibility of Fe3O4 as a potential material to adsorb mercury in Ciujung River water originating from industrial waste. The adsorption efficiency was assessed by examining the effects of pH, adsorbent weight, and contact time. In addition, the adsorption capacity of Fe3O4 was analyzed using adsorption kinetics and isothermal models. The findings of the study showed that the adsorption process of Hg(II) using Fe3O4 followed pseudo-first-order kinetics with an R2 value of 0.998. Furthermore, the research data correlated well with the Freundlich isotherm. After Hg(II) was treated with Fe3O4 for a contact time of 90 min, its concentration in pure water samples was reduced, with an adsorption capacity of 263.04 mg/g. The study also evaluated the reusability and stability of Fe3O4 to reduce Hg(II) in Ciujung River water samples. Fe3O4 achieved a maximum adsorption capacity of 218.17 mg/g and was able to selectively absorb Hg(II) even in the presence of other heavy metals, with a desorption rate of 99.39 %. The desorption rate remained high after the fifth cycle, with a value of 87.65 %. These results indicate that Fe3O4 has strong potential as an adsorbent for treating industrial wastewater from the Ciujung River.

Composite of Organo-LDH and biochar for diclofenac sodium removal from aqueous solutions

Classic layered double hydroxides (LDHs) and their composites with biochar are promising adsorbents for removing emerging contaminants like diclofenac sodium (DFS) from water. However, the use of organo-LDHs in these composites remains unexplored and could enhance their adsorption properties for organic molecules. This study investigates the synthesis, characterization, and application of an organo-LDH based on sodium dodecyl sulfate as intercalating agent (SDS-LDH) and its composite with tangerine peel biochar (SDS-LDH/BC) for the removal of DFS from water. The adsorption performance of these materials was compared with those of a composite of SDS-LDH and tangerine peel biomass (SDS-LDH/Bio) and the layered double oxides (LDOs) obtained from the pyrolysis of SDS-LDH and SDS-LDH/Bio, referred to as SDS-LDO and SDS-LDO/Bio, respectively. The materials were characterized by FTIR, XRD, SEM, TG, and pH point of zero charge analyses, and the adsorption of DFS was evaluated in aqueous medium under different conditions. XRD and FTIR demonstrated the successful incorporation of sodium dodecyl sulfate into the interlamellar space of the SDS-LDH, which was preserved in the SDS-LDH/BC and SDS-LDH/Bio composites. SEM analysis revealed that the SDS-LDH structures, with varied shapes and sizes, were dispersed on the matrix of the biochar, while TG analysis showed that the SDS-LDH/BC had similar thermal stability to SDS-LDH. SDS-LDH achieved 90 % DFS removal at pH 8.0 and 25 °C, while SDS-LDH/BC reached 81 % removal under the same conditions, with maximum DFS adsorption capacities of 247 and 169 mg g−1, respectively, outperforming pristine biochar (no removal). Under the same conditions, SDS-LDH/Bio, SDS-LDO/Bio, and SDS-LDO removed 55 %, 36 %, and 36 % of DFS, respectively. These results revealed the pivotal role of the interlamellar structure of SDS-LDH in DFS adsorption, as confirmed by XRD and FTIR, which indicated that DFS interacted with dodecyl sulfate anion in the SDS-LDH interlamellar space, specially through hydrophobic interaction. Kinetics studies revealed that DFS adsorption on SDS-LDH/BC followed the pseudo-first-order model, while adsorption on SDS-LDH followed the pseudo-second-order model, with equilibrium reached in approximately 30 min. The Redlich-Peterson model satisfactorily fitted the adsorption equilibrium isotherms for both SDS-LDH and SDS-LDH/BC. Although no synergistic effect was observed between biochar and SDS-LDH/BC regarding the adsorption capacity, the formation of the SDS-LDH/BC composite improved the preservation of the SDS-LDH structures, allowing for a lower loss of adsorption capacity upon reuse. These findings suggest that the study of such advanced material can contribute to the development of more effective biochar-LDH composite-based adsorbents, specifically for the removal of organic pollutants.

Efficient arsenic removal from water using iron-impregnated low-temperature biochar derived from henequen fibers: performance, mechanism, and LCA analysis

The present study aims to investigate the low-energy consumption and high-efficiency removal of arsenic from aqueous solutions. The designed adsorbent Fe/TBC was synthesized by impregnating iron on torrefaction henequen fibers. Isothermal adsorption experiments indicated maximum adsorption capacities of 7.30 mg/g and 8.98 mg/g for arsenic(V) at 25.0 °C and 40.0 °C, respectively. The interference testing showed that elevated levels of pH, HCO3− concentration, and humic acid content in the solution could inhibit the adsorption of arsenic by Fe/TBC. Characterization of the adsorbent before and after adsorption using FTIR and SEM–EDS techniques confirmed arsenic adsorption mechanisms, including pore filling, electrostatic interaction, surface complexation, and H-bond adhesion. Column experiments were conducted to treat arsenic-spiked water and natural groundwater, with effective treatment volumes of 550 mL and 8792 mL, respectively. Lastly, the life cycle assessment (LCA) using OpenLCA 2.0.3 software was performed to treat 1 m3 of natural groundwater as the functional unit. The results indicated relatively significant environmental impacts during the Fe/TBC synthesis stage. The global warming potential resulting from the entire life cycle process was determined to be 0.8 kg CO2-eq. The results from batch and column experiments, regeneration studies, and LCA analysis indicate that Fe/TBC could be a promising adsorbent for arsenic(V).

Potentiality of eggshell waste in synthesis of functional metal-organic frameworks for fuel purification

Nitrogen containing compounds in the liquid fuel are well-known to cause serious corrosive action on the engines and plugging of filters with the formation of gummy compounds. Hence, the removal of nitrogenated compounds from the liquid fuel is highly demanded. The current study focused on the efficient removal of indole and quinoline (as nitrogenated compounds) by Ca based metal organic framework. Formerly, Ca based metal organic framework was synthesized using eggshell wastes as source of Ca by Solvothermal [Ca-BTC (s)] and Microwave [Ca-BTC (m)] techniques. Flower and shell plates like crystals were observed under microscope for the synthesized Ca-BTC (s) and Ca-BTC (m), respectively. Purification of liquid fuel from indole and quinoline by the obtained Ca-BTC was systematically investigated. The adsorption of nitrogenated compounds followed the second order reaction and Langmuir isotherm. Microwave technique showed to be more preferable rather than solvothermal technique, for preparation of Ca-BTC with significantly higher adsorption capacity, whereas, and the affinity was higher towards quinoline compared to indole. Meanwhile, for Ca-BTC (m), the estimated maximum adsorption capacity of indole and quinoline was 490.7 mg/g and 583.4 mg/g, respectively. After 4 regeneration cycles, the adsorption capacity Ca-BTC (m) was lowered by 29 % for indole and 24 % for quinoline. The obtained results confirmed the successful using of eggshell wastes in preparation of Ca-BTC with remarkable efficiency in the liquid fuel purification with quite good recyclability.

Polyvinylpyrrolidone mediated electrospun ZnO-ZnFe2O4 composite nanofibers for removing malachite green from water

This study explores the application of ZnO-ZnFe2O4 composite nanofibers for the adsorption of Malachite Green (MG) dye from water. The composite nanofibers were fabricated using simple polyvinylpyrrolidone (PVP) mediated electrospinning method by changing zinc and iron precursor weight ratio named as Zn–Fe (1-1), Zn–Fe (2–1) and Zn–Fe (1–2). The diameter of 1D nanofibers was found to be 40–60 nm. The formation of hexagonal wurtzite structure of ZnO and cubic spinel structure of ZnFe2O4 was confirmed by XRD and HRTEM analysis. The effects of various parameters such as pH, contact time and initial concentration on the adsorption process were investigated. The Zn–Fe (1-1) nanofibers showed higher adsorption efficiency than other two. The adsorption results demonstrated excellent adsorption performance, with a maximum adsorption capacity of 146.77 mg/g at pH = 7 for Zn–Fe (1-1). Furthermore, the adsorption kinetics and isotherms were analyzed to understand the adsorption mechanism and equilibrium behaviour. It was found that the nanofibers material can be recycled and reused up to five cycles.

Synthesis of Some Eco-Friendly Materials for Gold Recovery.

The aim of this study was to develop new materials with adsorbent properties that can be used for the adsorption recovery of Au(III) from aqueous solutions. To achieve this result, it is necessary to obtain inexpensive adsorbent materials in a granular form. Concomitantly, these materials must have a high adsorption capacity and selectivity. Other desired properties of these materials include a higher physical resistance, insolubility in water, and materials that can be regenerated or reused. Among the methods applied for the separation, purification, and preconcentration of platinum-group metal ions, adsorption is recognised as one of the most promising methods because of its simplicity, high efficiency, and wide availability. The studies were carried out using three supports: cellulose (CE), chitosan (Chi), and diatomea earth (Diat). These supports were functionalised by impregnation with extractants, using the ultrasound method. The extractants are environmentally friendly and relatively cheap amino acids, which contain in their structure pendant groups with nitrogen and sulphur heteroatoms (aspartic acid-Asp, l-glutamic acid-Glu, valine-Val, DL-cysteine-Cys, or serine-Ser). After preliminary testing from 75 synthesised materials, CE-Cys was chosen for the further recovery of Au(III) ions from aqueous solutions. To highlight the morphology and the functionalisation of the material, we physicochemically characterised the obtained material. Therefore, the analysis of the specific surface and porosity showed that the CE-Cys material has a specific surface of 4.6 m2/g, with a porosity of about 3 nm. The FT-IR analysis showed the presence, at a wavelength of 3340 cm-1, of the specific NH bond vibration for cysteine. At the same time, pHpZc was determined to be 2.8. The kinetic, thermodynamic, and equilibrium studies showed that the pseudo-second-order kinetic model best describes the adsorption process of Au(III) ions on the CE-Cys material. A maximum adsorption capacity of 12.18 mg per gram of the adsorbent material was achieved. It was established that the CE-Cys material can be reused five times with a good recovery degree.

Enhanced cesium removal from wastewater using a potassium hexacyanoferrate/gelatin aerogel composite

In the wake of the 2011 Fukushima nuclear disaster, the presence of radioactive cesium (137Cs) in nuclear wastewater has posed a critical and enduring health risk. Addressing this challenge, we have synthesized a gelatin aerogel, denoted as KCuFC/GA, immobilized with potassium cupric ferrocyanide (KCuFC) through an in situ approach, aiming for the efficient extraction of 137Cs from aqueous environments. This novel aerogel's rich porous structure enhances the accessibility of adsorption sites, thereby significantly promoting the capture of Cs+. The adsorption of cesium onto KCuFC/GA was investigated under various experimental conditions, including initial solution pH, contact time, initial cesium concentration, and the presence of coexisting ions (K+, Na+, Ca2+, Mg2+, Sr2+). The results indicated that the adsorption performance was largely independent of pH, achieving a high cesium removal rate of 93.4 % within the first 5 minutes. The cesium adsorption data were well-described by the Langmuir adsorption model, indicating a maximum adsorption capacity of 222.22 mg·L−1. Furthermore, in the presence of various competing ions, KCuFC/GA has demonstrated unparalleled selectivity for Cs+, with a partition coefficient (Kd) of 2.49 × 105 mL·g−1, and has sustained its adsorptive properties across five cycles of use. Through systematic investigation, including X-ray photoelectron spectroscopy (XPS) analysis, we have elucidated the adsorption mechanism, highlighting the pivotal role of ion exchange between lattice K+ and Cs+. The straightforward fabrication process and the aerogel's robust cesium removal capabilities from complex solutions indicate that KCuFC/GA is a promising candidate for real-world applications in the treatment of radioactive wastewater.

Hierarchical porous ACNF/MIL-68(In)–NH2 composites for rapid and efficient removal of losartan from water: Unveiling adsorption mechanisms and superior performance

Losartan (LP), a medication commonly used to treat hypertension, has emerged as a potential environmental pollutant. Despite its widespread use, research on the efficient and rapid removal of LP from the environment remains very scarce. The limited studies on LP adsorption indicate that the adsorption capacity and rate of LP need improvement. In this study, we successfully prepared a hierarchical porous nitric acid-treated carbon nanofiber (ACNF)/MIL-68(In)–NH2 composite with a robust three-dimensional support structure using a simple hydrothermal method for the first time to adsorb LP. The resulting ACNF/MIL-68(In)–NH2 composite demonstrated exceptional adsorption capabilities, achieving an equilibrium absorption capacity of 259.87 mg/g within just 64 min, significantly outperforming previously reported results. Langmuir fitting indicated a maximum theoretical adsorption capacity exceeding 630 mg/g at 55 °C. For actual wastewater with low LP concentrations, complete removal was achieved with a minimal dose of the ACNF/MIL-68(In)–NH2 adsorbent. DFT calculations and Multiwfn wavefunction analysis revealed that the adsorption behavior of LP onto ACNF/MIL-68(In)–NH2 is primarily driven by electrostatic interactions, multiple hydrogen bonds, π-π stacking interactions, and van der Waals forces. This work presents an innovative strategy for the efficient and rapid removal of residual LP from water environments.

Sustainable application of modified Luffa cylindrica biomass for removal of trimethoprim in water by adsorption with process optimization.

The present study describes a set of methodological procedures (seldom applied together), including (i) development of an alternative adsorbent derived from abundant low-cost plant biomass; (ii) use of simple low-cost biomass modification techniques based on physical processing and chemical activation; (iii) design of experiments (DoE) applied to optimize the removal of a pharmaceutical contaminant from water; (iv) at environmentally relevant concentrations, (v) that due to initial low concentrations required determination by ultra-performance liquid phase chromatography coupled to mass spectrometry (UPLC-MS/MS). A central composite rotational design (CCRD) was employed to investigate the performance of vegetable sponge biomass (Luffa cylindrica), physically processed (crushing and sieving) and chemically activated with phosphoric acid, in the adsorption of the antibiotic trimethoprim (TMP) from water. The optimized model identified pH as the most significant variable, with maximum drug removal (91.1 ± 5.7%) achieved at pH 7.5, a temperature of 22.5°C, and an adsorbent/adsorbate ratio of 18.6mgµg-1. The adsorption mechanisms and surface properties of the adsorbent were examined through characterization techniques such as scanning electron microscopy (SEM), point of zero charge (pHpzc) measurement, thermogravimetric analysis (TGA), specific surface area, and Fourier-transform infrared spectroscopy (FTIR). The best kinetic fit was obtained by the Avrami fractional-order model. The hypothesis of a hybrid behavior of the adsorbent was suggested by the equilibrium results presented by the Langmuir and Freundlich models and reinforced by the Redlich-Peterson model, which achieved the best fit (R2 = 0.982). The thermodynamic study indicated an exothermic, spontaneous, and favorable process. The maximum adsorption capacity of the material was 2.32 × 102µgg-1 at an equilibrium time of 120min. Finally, a sustainable and promising adsorbent for the polishing of aqueous matrices contaminated by contaminants of emerging concern (CECs) at environmentally relevant concentrations is available for future investigations.

Multi-ligand strategy for enhanced removal of heavy metal ions by thiol-functionalized defective Zr-MOFs

Given the significant global concern about heavy metal pollution, the development of effective adsorbents to capture pollutants has become an urgent issue. In this work, thiol-functionalized defective Zr-MSA-DMSA was designed by mixing 2,3-dimercaptosuccinic acid and mercaptosuccinic acid, which was applied for the rapid and efficient removal of M(II) (i.e., Pb(II), Hg(II), Cd(II)) from wastewater. Zr-MSA-DMSA exhibited excellent adsorption performance, and the maximum adsorption capacities for Pb(II), Hg(II), and Cd(II) were 715.2 mg g−1, 862.7 mg g−1, and 450.5 mg g−1. In actual wastewater, Zr-DMSA-MSA exhibited up to 97 % M(II) removal efficiency and excellent anti-interference ability. It also maintained good structural stability after five adsorption/regeneration cycles. Thus, the abundant oxygen vacancies and unsaturated adsorption sites on Zr-MSA-DMSA significantly improved the adsorption performance of M(II). Spectral analysis and DFT calculations confirmed that Zr-MSA-DMSA mainly relied on the coordination of sulfur and oxygen atoms, electrostatic attraction and a large number of defective sites to achieve the adsorption of M(II). Fixed bed experiments showed that Zr-MSA-DMSA exhibited a depletion time of 10500 min and a volume of 7.0 L. In summary, Zr-MSA-DMSA holds significant potential for treating heavy metal wastewater and provides potential applications for defect engineering.

Superparamagnetic composites of lignin regenerated from ionic liquid solutions for the efficient and selective removal of cationic dyes

Magnetic lignin nanoparticles (MLNs) were prepared by inducing their self-assembly through lignin regeneration in the [N-methyl-2-pyrrolidone][C1–C4 carboxylic acid] ionic liquids ([NMP]ILs), which are low-cost protic ionic liquid. [NMP]ILs are self-assembling solvent that can enhance the adsorption capacity of MLNs to a greater degree than tetrahydrofuran or H2O. Additionally, the anion types of [NMP]IL greatly influence the physiochemical properties of MLNs. The MLNs prepared through self-assembly with [NMP][formate] (MLN/[NMP][For]) exhibited a higher maximum adsorption capacity (134.53 mg/g) than the [NMP]ILs of C2–C4 carboxylate anions. MLN/[NMP][For] demonstrated stable adsorption within a pH range of 6–10 or at high salt concentrations (0.01–0.5 mol/L), retaining over 80 % of its regeneration efficiency after 5 cycles. In addition, MLN/[NMP][For] selectively removed cationic dyes in mixed binary anionic–cationic dye solutions. This work demonstrated the feasibility of preparing magnetic biosorbents with good selectivity and stability though regeneration and by adjusting the anions of ionic liquids.

Fluorescence detection and effective adsorption of trace Pb(II) based on nanofibrous metal-organic gel

Water pollution has become a global environmental problem, such as that caused by Pb(II). Therefore, there is an urgent need to develop multifunctional materials for Pb(II) monitoring and removal. Yet, developing bifunctional materials for sensitive detection and efficient removal of Pb(II) remain challenging. Here, a metal-organic gel (HNU-G4) was constructed for sensible responsive detection and efficient adsorption of Pb(II). The dry gel was obtained through the freeze-dried process and can be used for the Pb(II) detection via fluorescence quenching; the lowest limit of detection for Pb(II) is 0.766 ppb. Furthermore, HNU-G4 has an effective maximum adsorption capacity of 480.00 mg·g-1 for Pb(II) in water. Additionally, the gel demonstrates excellent recoverability and interference resistance, which can be used in the detection and recovery of actual reclaimed water samples to prevent secondary contamination. This study developed a bifunctional gel material for sensitive detection and effective removal of Pb(II) from water, providing a suggested strategy to tackle the heavy metal contamination problem.

Efficient Adsorption and Elimination of Tm3+ for Enhanced Seed Germination Using Pillar[5]Arene Polymer.

While rare earth elements (REEs) are essential for modern technology, their production methods raise concerns for agriculture. Researchers are now exploring ways to control and recycle REEs pollution, aiming to minimize agricultural impacts and potentially even develop methods to utilize these elements for improved crop yields. Regarding this issue, a new type of pillar[5]arene polymer (Pol-P[5]-BTZP) has been designed and synthesized by click reaction to enhance the efficiency of adsorption and recovery of rare earth metals. This polymer incorporates the unique structure of 2,6-di-1,2,3-triazolyl-pyridine. The results of various analyses revealed that Pol-P[5]-BTZP exhibits excellent thermal stability, a high specific surface area, and well-distributed networks of micropores and mesoporous structures. The adsorption capacity of Pol-P[5]-BTZP for Tm3+, a representative REE, was evaluated using the Langmuir and Freundlich isothermal adsorption models with a maximum adsorption capacity (Qmax) of 127.71 mg/g. Furthermore, the versatility of Pol-P[5]-BTZP in adsorption and recovering various REEs was tested. In addition to its adsorption capabilities, the potential of Pol-P[5]-BTZP for rare earth recovery and reuse was assessed through experiments on the impact of Tm3+ and La3+ on seed germination. These experiments demonstrated the wide-ranging applicability of Pol-P[5]-BTZP in recovering and reusing REEs for green agriculture.

Core-shell V2O5- Gum ghatti grafted poly (acrylamide-co-methacrylic acid) adsorbent for the removal of methylene blue dye in water: Kinetic, equilibrium and thermodynamic studies

Herein, vanadium pentoxide (V2O5) encapsulated Gum ghatti grafted poly(acrylamide-co- methacrylic acid) adsorbent was synthesized to remove methylene blue dye from water. The materials were characterized by FTIR, TEM, SEM, Raman and XRD analysis. Batch adsorption studies were performed on the materials. Several variables' effects on methylene blue removal, including pH, contact time, initial dye concentration, and adsorbent dosage, were examined. Kinetics and thermodynamic analysis were also carried out for the adsorbent-adsorbate interaction to determine the maximum adsorption and mechanism for adsorption. By using UV-Vis spectrophotometric analysis, the dye concentration was evaluated both before and after adsorption. Langmuir, Freundlich, and Dubini-Radushkevic's isotherm models were used to analyze the adsorption data. Results showed a maximum adsorption efficiency of 92 % at a pH of 9 and 0.2 g as the maximum adsorbent dosage. The study followed the Langmuir isotherm model with a correlation coefficient (R2) of 0.9995. The results from the kinetic studies show a pseudo-second-order mechanism. The negative values of the Gibbs free energy change ΔG° ranging from −10.57 KJmol−1 to −9.64 Kmol−1 within the temperatures of 298 K to 313 K is an indication of a spontaneous process. A negative enthalpy change (ΔH° = −29.05 KJmol−1) shows an exothermic process and a negative entropy change (ΔS° = −0.06 KJmol−1) represents a highly ordered system. ANOVA in Microsoft Excel and other statistical analyses were used to evaluate the effects of time, pH, concentration, dose, temperature, and other factors on the effectiveness of dye adsorption. Importantly, every parameter that was investigated showed statistically significant impacts on the removal of dye (p < 0.05), revealing their important impact on the adsorption process.

Removal of per- and polyfluoroalkyl substances (PFAS) from water using magnetic cetyltrimethylammonium bromide (CTAB)-modified pine bark

Per- and polyfluoroalkyl substances (PFAS) have gained global attention in recent years due to their adverse effect on environment and human health. In this study, a novel and cost-effective sorbent was developed utilizing forestry by-product pine bark and tested for the removal of PFAS compounds from both synthetic solutions and contaminated groundwater. The synthesis of the adsorbent included two steps: 1) loading of cetyltrimethylammonium bromide (CTAB) onto the pine bark and followed by 2) a simple coating of magnetite nanoparticles. The developed sorbent (MC-PB) exhibited 100 % perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) removal from synthetic solution (10 µg/L PFOA and PFOS) and enabled quick magnetic separation. A rapid removal of PFOA (> 80 %) by MC-PB was observed within 10 min from synthetic PFOA solution and the adsorption equilibrium was reached within 4 h, achieving > 90 % removal of PFOA (dosage 2 g/L, PFOA 10 mg/L, initial pH 4.2). The PFOA adsorption kinetics fitted well to an optimized pseudo-order model (R2=0.929). Intra-particle diffusion and Boyd models suggested that the adsorption process was not governed by pore diffusion. The maximum PFOA adsorption capacity was found to be 69 mg/g and the adsorption isotherm was best described by the Dual Mode Model (R2=0.950). The MC-PB demonstrated > 90 % PFOA and PFOS removal from contaminated groundwater. Furthermore, both short- and long-chain perfluorosulfonic acids and 6:2 fluorotelomer sulfonate were efficiently removed resulting in 83.9 % removal towards total PFAS (2 g/L dosage).