Langmuir Model Research Articles

Utilization of Organic-Rich Materials for the Adsorption of Copper Ions from Aqueous Environments

This study investigated the suitability of moss peat and compost as adsorbents for removing copper ions from aqueous systems. Kinetic experiments were conducted at pH 4, 20 °C, and an initial copper ion concentration of 20 mM. Under these experimental conditions, moss peat and compost had a maximum adsorption capacity of 45.8 and 41.9 mg/g, respectively. The kinetic data was assessed using several models, and the data fitted well with the pseudo-second-order model for both adsorbents. Moreover, the analysis of the isotherm data showed that the Langmuir model could fit the data, suggesting that copper ions are chemically adsorbed onto moss peat and compost. The pH value of 4.5 was the most effective for the adsorption of copper ions onto moss peat and compost. At this pH value, the maximum adsorption capacities were 60.0 mg/g for moss peat and 56.9 mg/g for compost. The characterization of moss peat and compost before and after the interaction with copper ions indicated that surface precipitation was the dominant mechanism by which copper ions were removed from aqueous systems. Copper precipitation on the surface of moss peat was higher than that on the surface of compost, and it was found to be 7.7 wt% and 3.8 wt%, respectively. Overall, these findings highlight the potential of using moss peat and compost as effective adsorbents for copper ions in highly contaminated water, particularly industrial and mining effluent.

Improving Adsorption Efficiency of Recycled Activated Carbon from Household Water Purifiers through Sonication

Objectives:This study evaluated the potential of recycled activated carbon from household water purifiers as an adsorbent for removing methylene blue. It aimed to achieve resource recycling and dyeing wastewater treatment through the sonication modification of recycled activated carbon.Methods:After sieving recycled activated carbon from water purifiers to a particle size of 75-150μm, the material, in this paper referred to as PCB-S, was processed using sonication to enhance its adsorption capacity. The characteristics of PCB-S were analyzed using SEM, XRD and BET analysis. To evaluate its efficacy, adsorption experiments were carried out varying the following parameters: PCB-S dosage (0.05-0.6gL-1), pH (2.0-10.0), initial concentration of methylene blue (100mgL-1), reaction time (1440 min), and temperature (298 K). The data from these experiments were analyzed using first and second-order kinetic models to understand the reaction kinetics, and the adsorption efficiency was further compared using Langmuir and Freundlich isotherm models. Finally, the thermodynamic properties of the adsorption process between PCB-S and methylene blue were studied to determine its endothermic nature and spontaneity.Results and Discussion:The analysis of the surface characteristics of PCB and PCB-S revealed that sonication significantly altered the pore structure of the activated carbon, leading to increases in both the specific surface area and pore volume. XRD analysis, indicated that sonication had no impact on the crystalline or amorphous structure of the activated carbon. PCB-S demonstrated superior porosity and adsorption capabilities compared to PCB. With a dosage of 0.6gL-1, PCB-S was able to remove 65% of methylene blue from the solution. The adsorption kinetics were best described by a pseudo-second-order kinetic model, with the Langmuir adsorption isotherm fitting the data most accurately. The Gibbs free energy (-1.90~-1.32kJ mol-1) and enthalpy change (7.44 kJ mol-1) confirmed that the adsorption reaction was endothermic.Conclusion:This study confirmed that recycled activated carbon from water purifiers exhibits excellent effectiveness as a dye removal adsorbent when subjected to sonication treatment. Therefore, the possibility of utilizing recycled household water purifier filters as adsorbents is expected to contribute to reducing waste disposal costs by promoting resource recycling.

Fabricating Ultrathin Imprinting Layer for Fast Capture of Valsartan via a Metal Affinity-Oriented Surface Imprinting Method.

Rapid separation and enrichment of targets in biological matrixes are of significant interest in multiple life sciences disciplines. Molecularly imprinted polymers (MIPs) have vital applications in extraction and sample cleanup owing to their excellent specificity and selectivity. However, the low mass transfer rate, caused by the heterogeneity of imprinted cavities in polymer networks and strong driving forces, significantly limits its application in high-throughput analysis. Herein, one novel metal affinity-oriented surface imprinting method was proposed to fabricate an MIP with an ultrathin imprinting layer. MIPs were prepared by immobilized template molecules on magnetic nanoparticles (NPs) with metal ions as bridges via coordination, and then polymerization was done. Under the optimized conditions, the thickness of the imprinting layer was merely 1 nm, and the adsorption toward VAL well matched the Langmuir model. Moreover, it took just 5 min to achieve adsorption equilibrium significantly faster than other reported MIPs toward VAL. Adsorption capacity still can reach 25.3 mg/g ascribed to the high imprinting efficiency of the method (the imprinting factor was as high as 5). All evidence proved that recognition sites were all external cavities and were evenly distributed on the surface of the NPs. The obtained MIP NPs exhibited excellent selectivity and specificity toward VAL, with good dispersibility and stability. Coupled with high-performance liquid chromatography, it was successfully used as a dispersed solid phase extraction material to determine VAL in serum. Average recoveries are over 90.0% with relative standard deviations less than 2.14% at three spiked levels (n = 3). All evidence testified that the MIPs fabricated with the proposed method showed a fast trans mass rate and a large rebinding capacity. The method can potentially use high-throughput separation and enrichment of target molecules in batch samples to meet practical applications.

Chemical modification of Aspergillus flavus extracted chitosan for uranium remediation from aqueous solution

ABSTRACT Fungal chitosan derived from Aspergillus flavus AFC was employed in the synthesis of a cross-linked polystyrene biopolymer, P-AFC, which was investigated as a biosorbent material for the effective removal of uranium ions U(VI) from aqueous solutions. The characterisation of both fungal biopolymers was achieved using Brunauer-Emmett-Teller (BET) analysis, scanning electron microscopy (SEM), and Fourier-transform infrared (FTIR) spectroscopy. The efficacy of the P-AFC biosorbent in removing uranium from an aqueous solution reached equilibrium in 240 minutes at an initial uranium concentration of 50 ppm, a biosorbent amount of 0.4 g/L, and a pH of 4.0. The maximum biosorption capacity for U(VI) was determined to be 128.21 mg g−1 at room temperature, calculated using the Langmuir model. Furthermore, kinetic and thermodynamic analyses indicated that the biosorption process was characterised by chemisorption, was exothermic, and occurred spontaneously (ΔHo = –59.98 kJ mol−1 and ΔSo = –113.32 J K−1 mol−1). Recycling experiments demonstrated that the material could be reused up to five times without a noticeable decrease in removal efficiency.

EDTA functionalized pine needle biochar (EDTA@BC); a valorized bio-material for removal of Ni(II) from aqueous solution.

The preparation of ethylenediaminetetraacetic acid (EDTA) functionalized pine needles biochar (EDTA@BC) as a low-cost active adsorbent and its effectiveness in removing Ni(II) from aqueous solution at various conditions is reported in this paper. First, alkali activation was selected to render the pine needle biochar with an excellent porous structure and increased concentration of hydroxyl groups to facilitate grafting. Subsequently, a simple method was utilized to graft EDTA onto the biochar. The prepared EDTA@BC was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy dispersive x-ray spectrometry (EDX). Batch adsorption studies were conducted to assess the impact of various parameters such as solution pH, adsorbent dosage, adsorbate volume, and shaking time on the removal efficiency of Ni(II). At pH 6, 100 mg dosage, 4 mL of adsorbate volume, and 10 min of shaking time, the maximum removal efficiency of Ni(II) was observed to be 89%. EDTA@BC showed reasonable sorption performance still after the third cycle of regeneration. The effect of interfering ions such as Pb, Cr, Cu, and Hg was evaluated, resulting a decrease of 69%, 78%, 76%, and 68%, respectively, in its sorption capacity. The Langmuir model provided a better fit for Ni(II) in the concentration range of 0.1-2000 ppm under optimized conditions, with qmax of 46.69 ± 1.031 mg/g and KL of 0.001, compared with the Freundlich isotherm, which yielded n = 0.234 and χ2 = 2.7899, Temkin isotherm (R2 = 0.9520), and Redlich-Peterson isotherm (R2 = 0.9725). The removal of Ni(II) by EDTA@BC was found to be the pseudo-second-order kinetics. Thermodynamic studies indicated adsorption process to be endothermic and nonspontaneous. Hence, a sustainable valorized bio-material (EDTA@BC) is prepared having better sorption efficiency of Ni(II) from aqueous solution with possible wide applicability. RESEARCH HIGHLIGHTS: New EDTA functionalized indigenous pine needles biochar (EDTA@BC) was prepared. This low-cost active adsorbent found effective in removing Ni(II) from aqueous solution. FTIR, SEM, and EDX proved synthesis and uptake of Ni(II) from aqueous solution. Ni(II) removal, regeneration, interfering and adsorption studies were performed by UV-Vis spectroscopy.

Valorization of Cherry By-Products as Coagulant/Flocculants Combined with Bentonite Clay for Olive Mill Wastewater Treatment

In this study, two by-products resulting from the processing of cherry (stems and pits) were used as natural coagulants to promote the valorization of these wastes and treat olive mill wastewater (OMW). The efficacy of the plant-based coagulants (PBCs) in the coagulation–flocculation–decantation process (CFD) was evaluated through the removal of turbidity, total suspended solids (TSS), total polyphenols (TPh), and dissolved organic carbon (DOC). The CFD process was demonstrated to be effective in turbidity and TSS reduction in OMW. Using cherry stems (CSs), these reductions were 65.2% of turbidity and 58.0% of TSS, while cherry pits (CPs) achieved higher reductions, 78.6% of turbidity and 68.2% of TSS. To improve the effectiveness of OMW treatment, mainly regarding the removal of TPh and DOC, the CFD process was complemented with the adsorption process (using bentonite clay). The adsorption capacity of bentonite was higher in acidic conditions (pH 3.0) and, with a dosage of 3.0 g L−1, reached 17.3 mg of DOC and 13.8 mg of TPh per gram of bentonite. Several adsorption isothermal models were assessed, and the Langmuir (r2 = 0.985), SIPS (r2 = 0.992), and Jovanovic models (r2 = 0.994) provided the best fittings. According to the optimal operational conditions defined throughout the present work, the combination of CFD and adsorption removals were as follows: (1) 98.0 and 91.3% of turbidity, (2) 80.8 and 81.2% of TSS, (3) 98.1 and 97.6% of TPh and (4) 57.9 and 62.2% of DOC, for CSs and CPs, correspondingly. Overall, the results suggest that cherry by-products can be used as low-cost natural coagulants and, when combined with another natural, abundant, and cheap material, such as bentonite clay, can be a sustainable alternative for treating OMW.

Two approaches to prepare cationic lignin‐based adsorbents for efficient removal of phosphate ion from wastewater

AbstractIn this work, two types of cationic lignin‐based adsorbents (AL‐METAC and AL‐GTA) were prepared through free radical polymerization or etherification reaction of alkali lignin with 2,3‐epoxypropyl‐3‐trimethylammonium chloride or methylacrylloxyethyl trimethyl ammonium chloride (METAC). The contents of quaternary ammonium groups in the adsorbents were adjusted by changing the dosages of 2,3‐epoxypropyl‐3‐trimethylammonium chloride and METAC to fabricate the adsorbents with excellent adsorption capacity. The structures, aqueous solubility, and physical properties of adsorbents were analyzed. Meanwhile, the effects of adsorbents dosage, pH value of solution, temperature, and ionic strength on the adsorption capacity of adsorbents were also analyzed. These two types of adsorbents exhibited outstanding affinity for phosphate, with a maximum removal efficiency of 51.8 and 73.2 mg/g, respectively. The adsorption processes followed pseudo‐second‐order and Langmuir models well. In addition, the AL‐GTA exhibited higher removal efficiency than AL‐METAC. Moreover, the AL‐METAC and AL‐GTA still retained 69.7% and 69.0% adsorption capacity after four times regeneration. The fabricated lignin‐based adsorbents have potential applications in the removal of phosphate from wastewater, which would promote the high‐value application of lignin.

Removal of carcinogenic chromium(VI) from effluent of electroplating industry using adsorptive separation

AbstractThe wastewater from an electroplating industry contains chromium VI which is highly carcinogenic at a typical level of 21.5 to 47 mg L−1 which should be reduced to acceptable value of 0.05 mg L−1 for the water to be suitable for drinking purpose. In this study, Tulsion A23 resin was applied as an adsorbent for successful removal of Cr(VI), also dealing with understanding the effect of various parameters on extent of removal of the contaminant. It was elucidated that contact time of 120 min is required for the equilibrium and the optimum pH value was 5 and the optimum resin loading was 4 g L−1 at which 97% Cr(VI) removal was observed. Different adsorption isotherm models were applied and it was elucidated that Langmuir model was the best fit with R2 as 0.99. In the case of kinetic study, pseudo‐second order model was best fitted with higher R2 value. The regeneration of the resin was performed using 3 M NaOH and it was shown that after the three cycles of regeneration, the resin showed 82% Cr(VI) removal. Overall, successful application of Tulsion A23 resin was demonstrated for the removal of Cr(VI) from real effluent for the first time.

Adsorptive removal of synthetic dye from its aqueous solution by using chitosan-bentonite composite: DFT and experimental studies

AbstractThis research investigates the adsorption efficiency of a chitosan-bentonite (Ch–B) composite in removing methyl orange (MO), a common textile dye, from aqueous solutions. The study integrates experimental and theoretical analyses, employing density functional theory (DFT) to gain insights into the molecular interactions between the composite material and MO molecules. The Ch–B composite was characterized using various techniques, including FT-IR spectroscopy, XRD, and SEM–EDX. The experimental results indicate that the Ch–B composite exhibits a high adsorption capacity for MO, with optimal conditions identified for efficient removal. The Langmuir model was found to best fit the experimental data and the adsorption capacity was 117 mg g−1. Adsorption thermodynamics showed that the adsorption process was spontaneous, feasible, and exothermic. DFT calculation results are correlated with experimental findings to confirm theoretical predictions and improve the overall understanding of the adsorption process. Electronic structure calculations reveal the nature of the interactions between the Ch–B composite and MO molecules, including hydrogen bonds and electrostatic forces.

Adsorption of Pb, Cu, and Ni Ions on Activated Carbon Prepared from Oak Cupules: Kinetics and Thermodynamics Studies

Agricultural residue-activated carbon and biochar, inexpensive and environmentally friendly adsorbent materials, have recently received significant research attention. This study investigated the potential use of oak cupules in activated carbon form to remove widespread heavy metals (Pb2+, Cu2+, and Ni2+) from wastewater. The oak-activated carbon was prepared from oak cupules and activated with phosphoric acid. Oak-activated carbon was characterized using FTIR, BET analysis, energy-dispersive X-ray spectrometry (EDS), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The Freundlich, Langmuir, and Temkin isotherm models were used to assess the equilibrium data. The impact of various parameters, including pH effect, temperature, adsorbent dose, and contact time, was estimated. The Freundlich model was the most agreeable with Pb2+ adsorption by oak-based activated carbon, and Langmuir was more compatible with Cu+2 and Ni+2. Under optimum conditions, the average maximum removal was 63% Pb2+, 60% Cu2+, and 54% Ni2+ when every ion was alone in the aqueous solution. The removal was enhanced to 98% Pb2+, 72% Cu2+, and 60% Ni2+ when found as a mixture. The thermodynamic model revealed that the adsorption of ions by oak-based activated carbon is endothermic. The pseudo-second-order kinetic best describes the adsorption mechanism in this study; it verifies chemical sorption as the rate-limiting step in adsorption mechanisms. The oak-activated carbon was effective in removing Pb2+, Cu2+, and Ni2+ from wastewater and aqueous solutions.

Development of pH-responsive Eudragit S100-functionalized silk fibroin nanoparticles as a prospective drug delivery system.

Silk fibroin nanoparticles (FNP) have been increasingly investigated in biomedical fields due to their biocompatibility and biodegradability properties. To widen the FNP versatility and applications, and to control the drug release from the FNP, this study developed the Eudragit S100-functionalized FNP (ES100-FNP) as a pH-responsive drug delivery system, by two distinct methods of co-condensation and adsorption, employing the zwitterionic furosemide as a model drug. The particles were characterized by sizes and zeta potentials (DLS method), morphology (electron microscopy), drug entrapment efficiency and release profiles (UV-Vis spectroscopy), and chemical structures (FT-IR, XRD, and DSC). The ES100-FNP possessed nano-sizes of ∼200-350 nm, zeta potentials of ∼ -20 mV, silk-II structures, enhanced thermo-stability, non-cytotoxic to the erythrocytes, and drug entrapment efficiencies of 30%-60%, dependent on the formulation processes. Interestingly, the co-condensation method yielded the smooth spherical particles, whereas the adsorption method resulted in durian-shaped ones due to furosemide re-crystallization. The ES100-FNP adsorbed furosemide via physical adsorption, followed Langmuir model and pseudo-second-order kinetics. In the simulated oral condition, the particles could protect the drug in the stomach (pH 1.2), and gradually released the drug in the intestine (pH 6.8). Remarkably, in different pH conditions of 6.8, 9.5, and 12, the ES100-FNP could control the furosemide release rates depending on the formulation methods. The ES100-FNP made by the co-condensation method was mainly controlled by the swelling and corrosion process of ES100, and followed the Korsmeyer-Peppas non-Fickian transport mechanism. Whereas, the ES100-FNP made by the adsorption method showed constant release rates, followed the zero-order kinetics, due to the gradual furosemide dissolution in the media. Conclusively, the ES100-FNP demonstrated high versatility as a pH-responsive drug delivery system for biomedical applications.

Synthesis and characterization of Novel Igepal Co-520 surfactant coated Fe3O4 Nanoparticles: An evaluation of Vanadium enrichment in spice samples

In this study, novel Fe3O4 nanoparticles coated with surfactant Igepal Co-520 (polyoxyethylene (5) nonylphenylether) as adsorbent were synthesized, and total vanadium recovery was performed by magnetic solid phase extraction (MSPE) method. Fe3O4 nanoparticles coated with Igepal Co-520 were employed in the investigation of vanadium enrichment. The synthesized nanoparticles were characterized by Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive X-Ray Analysis (EDX), X-Ray Diffraction Analysis (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Thermogravimetric Analysis (TGA), and total vanadium concentration was determined by Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The corresponding values for the pH, adsorbent amount, and contact time were 3, 5 mg, and 120 min. Total vanadium was recovered from an aqueous solution under the optimum conditions. Langmuir and Freundlich adsorption isotherms, pseudo-first and pseudo-second order adsorption kinetics, foreign ion studies, desorption, and analytical value studies were performed. In isotherm studies, the effect on adsorption was examined by varying the vanadium concentration between 1 mg/L and 100 mg/L. The Langmuir model (R2>0.99) seems to be more compatible with vanadium adsorption than the Freundlich model (R2<0.87). Pseudo−first-order and pseudo-second-order equations were used to evaluate adsorption kinetic models. It has been observed that the pseudo-quadratic equation (R2>0.89) was more suitable for modeling than the pseudo-first-order equation (R2<0.56). The analytical performance parameters of the method were calculated as enrichment factor (EF) 114, the limit of detection (LOD) 8.3 µg/L, the limit of quantification (LOQ) 28.3 µg/L, and relative standard deviation (RSD) 1.20 %. At various molarities, the effects of acidic (HCl) and basic (NaOH) agents on the desorption of total vanadium ions adsorbed on the magnetic Fe3O4 surface were examined and compared. It was observed that the maximum recovery (100 %) was obtained using HCl as the desorption agent. The total vanadium concentration in spice samples was measured in an actual sample analysis. All the results demonstrate that the Fe3O4@Igepal Co-520 was successfully synthesized and has the potential to be a useful tool for heavy metal recovery.

Zinc oxide nanoparticles encapsulated in alginate beads: a promising and recyclable adsorbent for simultaneous uptake of toxic metals.

Heavy metal toxicity is a known problem and various methods are used for treatment. Adsorption has some advantages and it would be promising if environmentally friendly and cheap materials were utilized. Alginate and zinc oxide nanoparticles were selected and composite alginate beads were used for the removal of mixed metals from aqueous solutions. Batch and column experiments were conducted to determine some parameters' effects and the adsorbent's real application potential. According to the batch experiments, zinc oxide nanoparticles to alginate ratio of 0.5 g/g, and pH levels nearby to the neutral range led to better metal removals. 0.5 ml/min of flow rate supplied better metal removal efficiencies in columns, with the highest treatment as 86% of Pb2+. Acid treatment can be successfully applied for the regeneration of the adsorbent, at least three times only with a 4% reduction in the adsorption efficiency. Heavy metal uptake was compatible with the Pseudo 2nd order model indicating chemisorption as a dominant mechanism. Also, the intraparticle diffusion model illustrated adsorption might govern more than one step. The Langmuir model had the best fit and suggested monolayer covering for Pb2+, 76.3 mg/g. Alginate-based nanocomposite beads were useful for mixed metal removal and could be used.&#xD.

Ultralight molybdenite-doped and phosphate rich alginate composites exhibiting superb chelating ability for UO22+: Adsorption thermodynamics, kinetics and mechanistic evaluation

In the present research work, molybdenite-doped and phosphate-rich alginate composites (MDPA) were developed for uranium removal from aqueous medium and characterized through different analytical techniques such as XPS, FTIR, XRD, SEM-EDS, and elemental mapping. The mass ratio of molybdenite in different MDPA hydrogel beads was optimized, and it was concluded that MDPA-II material (having 22.5% w/w MoS2) has superb chelating ability for UO22+ ions from aqueous solution. The XPS data showed the involvement of S coordination with UO22+ species. It proves that the UO22+ ions bonded to MoS2 surfaces by forming a U-S bond. Moreover, phosphate (OPO3-) group of phytic acid and SMo=S linkages of molybdenite reinforced inner-spherical complexation with UO22+ ions. Kinetics followed pseudo-second-order rate model (R2≈0.99) and equilibrium sorption data found in close agreement with the Langmuir and Temkin models (R2≈0.99). The qm (mg/g) at 298 K was found to be 311.16±7.76 mg/g at optimized pH of 4.5. The study shows the improved sorption performance of MDPA-II hydrogel beads for the uranium competitive recovery.

Adsorption properties of Pb(II) and Cd(II) in acid mine drainage by oyster shell loaded lignite composite in different morphologies

A new idea to alleviate environmental pollution is the development of low-cost adsorbents using natural minerals and fishery wastes to treat high concentrations of heavy metal pollutants in acid mine drainage (AMD). Adsorbent morphology, adsorptive and regenerative capacity, and application potential are limiting factors for their large-scale use. Oyster shells capable of releasing alkalinity were loaded on the surface of lignite to develop two composite adsorbents with different morphologies (powdery and globular) for the treatment of AMD containing Pb(II) and Cd(II). The results show that the ability of the adsorbent to treat AMD is closely related to its morphologies. The pseudo-second-order kinetic model and the Langmuir model are suitable to describe the adsorption process of OS-M(P), and the maximum adsorption saturation capacities of Pb(II) and Cd(II) are 332.6219 mg/g and 318.9854 mg/g, respectively. The pseudo-second-order kinetic model and the Freundlich model are suitable to describe the adsorption process of OS-M(G). A synergistic result of electrostatic adsorption, neutralization precipitation, ion exchange and complex reaction is achieved in the removal of Pb(II) and Cd(II) by two morphologies of adsorbents. The regeneration times (5 times) and recovery rate (75.75%) of OS-M(G) are higher than those of OS-M(P) (3 times) and recovery rate (20%). The ability of OS-M(G) to treat actual AMD wastewater is still better than that of OS-M(P). OS-M(G) can be used as a promising environmentally friendly adsorbent for the long-term remediation of AMD. This study provides a comprehensive picture of resource management and reuse opportunities for natural mineral and fishery wastes.

Equilibrium, Kinetic, and Diffusion Mechanism of lead(II) and cadmium(II) Adsorption onto Commercial Activated Carbons

The adsorption of Pb(II) and Cd(II) on three commercial microporous activated carbons was analysed. Adsorption kinetics and statistics were investigated, and the results were described with different models. The highest values of the correlation coefficient R2 were obtained for the pseudo-second-order kinetics model for all ions tested and all sorbents used. The adsorption process was found to be determined by both diffusion in the liquid layer and intraparticle diffusion. The adsorption equilibrium is very well described by Langmuir, Temkin, Thoth or Jovanovic isotherm models. Based on the values of n from the Freundlich isotherm and KL from the Langmuir isotherm, the adsorption of cadmium and lead ions was found to be favourable. The highest monolayer capacities were obtained during the adsorption of lead ions (162.19 mg/g) and for cadmium (126.34 mg/g) for activated carbon WG-12. This carbon is characterised by the highest amount of acid functional groups and the largest specific surface area. The adsorption efficiency of the tested ions from natural water is lower than that from a model solution made from deionised water. The lowest efficiencies are obtained when the process occurs from highly mineralised water.

Removal of beryllium (Be2+) from aqueous solution by 5-sulfosalicylic acid-loaded anion-exchange resin

AbstractThis study presents the preparation and application of a 5-sulfosalicylic acid-loaded anion-exchange resin to remove Be2+ from aqueous solutions. Optimization efforts focused on critical parameters, including resin dosage, initial solution pH, and the influence of interfering ions. Results indicate an optimal resin dose of 0.3 g and a working pH of ≥ 4.0 for maximal Be2+ removal efficiency. Kinetic analysis reveals rapid removal kinetics, with 99% removal achieved within 45 min. Notably, the resin exhibits remarkable selectivity, maintaining consistent removal rates for Be2+ even in the presence of common interfering ions such as Na+, K+, Ca2+, Mg2+, and Fe2+. Sorption isotherms fitting the Langmuir model further support the resin's effectiveness in Be2+ removal. Thermodynamic evaluation suggests the removal process is spontaneous (∆G° &lt; 0) and endothermic (∆H° &gt; 0), indicating favorable energetics. Crucially, the Be-loaded resin is easily regenerated using 0.1 M HCl, enhancing its practical applicability. These results highlight the effectiveness and potency of the prepared resin in Be2+ removal, suggesting promising solutions for addressing environmental contamination.

Removal of the bemacid blue E-TL using granular activated carbon from abundant biomass: adsorption isotherm, thermodynamic and kinetic studies

In this work, we were interested in the adsorption of an acid dye, Bemacid Blue E-TL by granular activated carbon based on olive stones. To shed light on the adsorption process, batch experiments were performed to study the effect of operating parameters on the adsorption process such as equilibrium time, GAC dose, pH, initial dye concentration, and temperature. The experimental results showed that the adsorption of the dye Bemacid Blue E-TL by GAC based on olive stones depends on the equilibrium time at 8 hours, the pH is 2 of the solution and the dose is 5 g.L-1. To explain the adsorption equilibrium, the experimental values were examined by Langmuir, Freundlich, and Temkin models. The equilibrium is perfectly described by the Langmuir model whose correlation coefficient is higher than 0.99. The maximum retained quantity of the Bemacid Blue E-TL is 55.6 mg.g-1. Different kinetic models such as pseudo-first order, pseudo-second order, and the intraparticle diffusion equation were used to evaluate the adsorption kinetics. The results of the kinetic modeling showed that the pseudo-second order fitted the data well, with a high coefficient of determination (R2 &gt; 0.99) and intra-particle diffusion is not the only rate-limiting step. The thermodynamic parameter values enthalpy (ΔH°), entropy (ΔS°), and energy change (ΔG°) show that the adsorption processes are endothermic and spontaneous. The various results obtained are promising and encouraging to consider a more comprehensive study with the objective of showing that the adsorbent chosen for this study is effective and could be used as a low-cost adsorbent for acid dye removal.

Immobilizing of polyethyleneimine on bamboo viscose fiber using epichlorohydrin crosslinker for enhancing adsorption ability with lac dye

AbstractImmobilization of polyethyleneimine (PEI) on bamboo viscose fiber using epichlorohydrin (ECH) crosslinker (ABF‐e‐PEI) was employed to enhance the ability of dyeing with lac. The results from morphological observation, thermal degradation behavior, Fourier transform infrared (FTIR) analysis, x‐ray photoelectron spectroscopy (XPS) and x‐ray diffraction (XRD) clearly revealed the success of PEI‐immobilizing on fiber surface with no significant change in intrinsic properties of the fiber after modification. The modified fiber exhibited fast and efficient adsorption with the adsorption capacity &gt;90 mg/g which was much higher than that of the unmodified adsorbent (did not exceed 10 mg/g). The results from kinetic and isotherm studies showed that the adsorption process conformed to the pseudo‐second‐order, intra‐particle diffusion and Langmuir models. Adsorption temperatures have less effect to the adsorption performance of the modified adsorbent. Electrostatic ion‐dipole interaction between protonated amines of PEI and negative charged sites of lac dye was the main proposed mechanism. Good resistance of color changes for ABF‐e‐PEI was confirmed by the color‐fastness assessment (grade 4–5), suggesting efficient method of PEI‐immobilizing using ECH crosslinker. The binding reaction of between amine groups of PEI and hydroxyl groups of the cellulosic fiber using ECH crosslinker can be expected to have a broad potential application in dyeing processes or pollution treatments due to its simple, cost‐effective, flexible and efficient method.

Utilizing olive leaves biomass as an efficient adsorbent for ciprofloxacin removal: characterization, isotherm, kinetic, and thermodynamic analysis.

Olive leaves were utilized to produce activated biomass for the removal of ciprofloxacin (CIP) from water. The raw biomass (ROLB) was activated with sodium hydroxide, phosphoric acid, and Dead Sea water to create co-precipitated adsorbent (COLB) with improved adsorption performance. The characteristics of the ROLB and COLB were examined using SEM images, BET surface area analyzer, and ATR-FTIR spectroscopy. COLB has a BET surface area of 7.763 m2/g, markedly higher than ROLB's 2.8 m2/g, indicating a substantial increase in adsorption sites. Through investigations on operational parameters, the optimal adsorption efficiency was achieved by COLB is 77.9% within 60min, obtained at pH 6, and CIP concentration of 2mg/mL. Isotherm studies indicated that both Langmuir and Freundlich models fit the adsorption data well for CIP onto ROLB and COLB, with R2 values exceeding 0.95, suggesting effective monolayer and heterogeneous surface adsorption. The Langmuir model revealed maximum adsorption capacities of 636mg/g for ROLB and 1243mg/g for COLB, highlighting COLB's superior adsorption capability attributed to its enhanced surface characteristics post-modification. Kinetic data fitting the pseudo-second-order model with R2 of 0.99 for ROLB and 1 for COLB, along with a higher calculated qe for COLB, suggest its modified surface provides more effective binding sites for CIP, enhancing adsorption capacity. Thermodynamic analysis revealed that the adsorption process is spontaneous (∆Go < 0), and exothermic (∆Ho < 0), and exhibits a decrease in randomness (∆So < 0) as the process progresses. The ΔH° value of 10.6kJ/mol for ROLB signifies physisorption, whereas 35.97kJ/mol for COLB implies that CIP adsorption on COLB occurs through a mixed physicochemical process.