Experimental Adsorption Data Research Articles

Application of a magnetic graphene nanocomposite modified with 5-aminoisophthalic acid amine group for chromium (VI) adsorption from aqueous solutions: kinetic and thermodynamic studies

ABSTRACT Polymer nanocomposites are composite materials that incorporate nanomaterials, such as magnetic graphene oxide (mGO), into a polymer matrix. To enhance its adsorption capacity, the surface of mGO nanoparticles was polymerised by a 5-aminoisophthalic acid amine group (mGO-AIPA) through a simplified co-precipitation method. The structural and morphological characteristics of the synthesised nanoparticles were evaluated through techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Thermogravimetric analysis (TGA), and Vibrating sample magnetometer (VSM). Response surface method (RSM) was used to evaluate the effectiveness of mGO-AIPA nanocomposite in removing chromium (VI) ions by examining variables such as solution of pH, contact time, adsorbent dose and initial concentration. Also, the study of kinetic models, adsorption isotherms and thermodynamic modelling of the process were evaluated. The results found that the mGO-AIPA nanocomposite has the maximum removal of chromium (VI) ions from the aqueous solution by 83.11% in optimal conditions including pH 3.5, contact time of 35 min, an adsorbent dosage of 25 mg g−1 and an initial concentration of 55 mg L−1. The pseudo-second-order kinetic and Langmuir isotherm models had a better fit with the experimental data of adsorption and the maximum adsorption capacity of chromium (VI) the base of the Langmuir model was 90.91 mg g−1. Moreover, the thermodynamic analysis indicated that the process was exothermic and nonspontaneous process, implying that it was energetically unfavourable. These findings suggest that the mGO-AIPA nanocomposite has a high performance as an effectual adsorbent to eliminate chromium heavy metal from an aqueous medium.

The role of the activation heating source on the carbon capture performance of two new adsorbents produced from household-mixed-plastic waste

This study reveals the impact of the activation with microwave and conventional heating sources on textural properties and CO2 uptake of a mixed plastic-based char. Two mixed plastic-based adsorbents, one activated using microwaves and the other using conventional heating, were produced at optimum activation conditions, and subsequently compared. The findings show that both heating sources produced microporous adsorbents, but activation heating sources influenced their physicochemical properties and CO2 uptake. The microwave-produced activated carbon (AC) displayed superior BET surface area, total, micro- and ultra-micropore volumes compared to the conventionally produced AC. The microwave-produced AC possessed CO2 adsorption capacities of 1.66 and 2.37 mmol/g under dynamic and equilibrium conditions, respectively, at 25 °C and 1 bar. These capacities represent an 8 and 30 % higher uptake, respectively, compared to the 1.53 and 1.66 mmol/g displayed by the conventionally prepared AC under the same adsorption conditions. Both samples displayed stable and excellent CO2 recyclability over 10 adsorption-desorption cycles, with desorption efficiencies ranging from 93.46 % to 96.72 % (microwave- and conventionally- produced ACs respectively). The Avrami model most accurately described the experimental CO2 adsorption data under dynamic conditions, while the Sip model gave the best fit for equilibrium conditions. These findings apply to both types of ACs at various temperatures, irrespective of the heating source. Overall microwave heating is more efficient than conventional heating, requiring 300°C lower temperature, 115 minutes shorter time, 0.79 kWh less energy, and less KOH. It improves CO2 uptake and reduces production costs by 80 %, offering a sustainable alternative for CO2 adsorbent production.

Highly phosphorylated cellulose toward efficient removal of cationic dyes from aqueous solutions

Highly phosphorylated cellulose was produced under different processing parameters and used as an effective adsorbent for methylene blue (MB) dye removal from aqueous systems. The characteristics of the designed adsorbent were analyzed using different technics. The zeta potential measurement of the developed adsorbents was negative (−11.3 to −49.4 mV) in the pH range of 4 to 11. Batch removal tests were performed under different processing parameters of contact time, initial concentration, phosphorylation degree and pH. The developed adsorbent with a high substitution degree of 1.07 (13.22 % of P), revealed an outstanding retention capacity for MB dye (up to 3153.5 mg/g) during an extremely low equilibrium adsorption time (∼30 min), which is 130-fold higher than pure MCC (15.3 mg/g). Interestingly, this capacity raised up to 3236.6 mg/g when raising the pH of the solution (from 7 to 11). The experimental adsorption data in the examined conditions were well fitted by the Langmuir type isotherm and pseudo-second-order kinetic models, highlighting the significance of the reaction medium and phosphate content in determining the adsorbent's retention capacity. This investigation has demonstrated the potential of converting pure MCC into high value-added adsorbent for the efficient purification of organic dye from aqueous solutions.

Comparison of the natural and surfactant-modified zeolites in the adsorption efficiency of sunset yellow food dye from aqueous solutions

The removal of Sunset Yellow (E110) on natural zeolite and zeolite modified with the cationic surfactant cetyl pyridinium chloride (CPC) was studied using the adsorption method. The structural characteristics of the surfactant-modified zeolite (SMZ-CPC) were investigated using X-ray diffraction(XRD), Fourier transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) analysis, and the scanning electron microscopy (SEM) images. The effect of different parameters on the adsorption process, such as equilibration time and amount of adsorbent at 298 K, were determined using UV–Vis spectroscopy. The maximum dye removal percentage on SMZ-CPC was obtained with 0.08 g of adsorbent in 30 min. The results show that the zeolite modified with CPC surfactant (SMZ) has a higher adsorption capacity for Sunset Yellow than the unmodified zeolite (natural form). The experimental adsorption data were nonlinearly analyzed using isotherm equations such as Langmuir, Freundlich, Temkin, Langmuir-Freundlich (or Sips), and Extended Langmuir (EL). The experimental data were better fitted with the Sips isotherm. The adsorption kinetic data were analyzed using eight models in nonlinear forms: the pseudo-first-order (PFO), pseudo-second-order (PSO), integrated kinetic Langmuir (IKL), Elovich, intraparticle diffusion (IPD), mixed order rate equation (MOE), fractal-like pseudo-first-order (FL-PFO) and fractal-like pseudo-second-order (FL-PSO). According to the results of the coefficient of determination (R2), Elovich kinetic model well expressed E110 adsorption onto SMZ-CPC. Most of the dye removal takes place in less than 5 min and the maximum adsorption capacity is 5.06 mg/g. The results of this study show that zeolite modified with cationic surfactant is an effective adsorbent for removal anionic dyes from an aqueous solution.

Alginate-Based Hydrogel Bead Reinforced with Montmorillonite Clay and Bacterial Cellulose-Activated Carbon as an Effective Adsorbent for Removing Dye from Aqueous Solution.

According to environmental concerns related to water pollution, this study aims to develop a novel hydrogel bead as a biocompatible and efficient adsorbent by integrating bacterial cellulose-activated carbon (BCAC) and montmorillonite (MT) in alginate hydrogel (ALG). The ionotropic gelation method was applied to the fabrication of BCAC/MT/ALG hydrogel beads. The BCAC/MT/ALG hydrogel bead exhibited significantly higher tensile strength, Young's modulus, and thermal stability, with ~1.4 times higher adsorption uptake of methylene blue (MB) from aqueous solution as compared to the pristine ALG bead. The textural properties, including specific surface area and porosity, were beneficial to accommodate the size of cationic MB as the target molecule. This resulted in a remarkable MB adsorption uptake of 678.2 mg/g at pH 7 and 30 °C. The adsorption isotherm showed the best fit for the nonlinear Redlich-Peterson isotherm model. Experimental adsorption data were well-described by the pseudo-second order kinetic model, with R2 values reaching 0.997. In addition, the adsorbent bead demonstrated easy regeneration with high reusability with approximately 75% of MB removal after being used for six cycles. Therefore, BCAC/MT/ALG bead represents an eco-friendly, cost-effective, and highly efficient adsorbent for MB removal from water and could potentially be used for removal of a wide range of cationic dye pollutants from wastewater.

Management of trihalomethanes in water by ZnO@kaolinite composite: integrated experimental and modeling studies.

The adsorption of trihalomethanes (THMs) from drinking water was investigated in the current study through comparison studies of kaolinite and ZnO@kaolinite nanocomposites. The clay structural network's successful immobilization on the zincite hexagonal structure of ZnO nanoparticles' lattice layers was verified by the SEM/EDX analysis. Under the optimum conditions, the maximum removal of THMs was achieved by kaolinite and ZnO@kaolinite nanocomposites after 60 min. The adsorption performance of the ZnO@kaolinite nanocomposites was greater than that of kaolinite because the former had a larger surface area than the latter. The Freundlich isotherm model best matched the adsorption experimental data, which also reveals the existence of multilayer adsorption on a diverse surface with the greatest correlation (R2 = 0.956 and 0.954, respectively) for both nanoadsorbents using the pseudo-first-order (PFO), pseudo-second-order (PSO), mixed 1, 2-order (MFSO), and intraparticle diffusion (IPD) models. The mechanism by which THMs in drinking water adsorb onto nanoadsorbents was examined. This revealed that both intraparticle and film diffusion were involved in the adsorption process. Kaolinite and ZnO@kaolinite nanocomposites can be used in water treatment to remove THMs due to their great recyclable and reusable properties, even after six cycles.

Biosorptive removal of toxic nitrate ion from wastewater using Albizia lebbeck seed pods: Isotherm and equilibrium studies

A major environmental issue that contaminates drinking water and endangers human health is nitrate pollution. In this study, goethite, citric acid, tartaric acid was employed to modify Albizia lebbeck seed pod for the biosorption of nitrate ion. The developed unmodified Albizia lebbeck (UALB), citric acid modified Albizia lebbeck (CALB), tartaric acid modified Albizia lebbeck (TALB), and goethite acid modified Albizia lebbeck (GALB) were characterized using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), and point of zero charge (pHpzc) to determine the structural morphology, functional group, and adsorbent surface charge. The adsorption nitrate ion onto the biosorbents was found to be dependent on the operating parameters. The findings revealed that the maximum percentage removal of nitrate ion was 80.8 % at pH 7 for UALB, 80.3 % at pH = 4.0 for CALB, 70.30 % at pH = 3.0 for TALB and 76 % at pH 7 for GALB. The adsorption experimental data for nitrate ion adsorption onto ULAB, CALB, TALB, and GALB were best described by the Langmuir isotherm model. The UALB exhibited the highest Langmuir monolayer adsorption capacities with a value of 344.827 mg/g. Therefore, the unmodified form of Albizia lebbeck (UALB) which is economical, and sustainable provides an efficient alternative method for nitrate removal in aqueous environment.

Characterization of Pore Structure and Fluid Mobility of Shale Reservoirs.

Accompanying the commercial exploitation of shale oil and gas in North America, shale oil has gradually become an important resource, sparking great interest among countries around the world in recent years. In this study, focusing on the Paleogene Shahejie Formation in Bohai Bay (Eastern China), techniques such as CT, nitrogen adsorption, mercury injection capillary pressure (MICP), and nuclear magnetic resonance (NMR) were used to characterize the pore structure and mobility of the shale reservoir. Based on the X-ray CT data, the pore radius of the shale reservoir is in the range 0.5-65 μm, and the pore coordination number is concentrated in the range of 1-4. The shale reservoir is poorly connected. The minimum size of the unit body for establishing the digital core model is 380 μm. Based on the experimental data of nitrogen adsorption and MICP, the pores of shale in the study area are mainly classified as ink-bottle-shaped pores, transition-shaped pores, and flat plate slit-shaped pores. The specific surface area and volume of pores are mainly attributed to meso- and macropores. The movable fluid saturation of shale is distributed from 23.59 to 44.42%, the pore throat radius is distributed from 0.001 to 6 μm, and the lower limit of the movable pore throat radius of shale is distributed between 9.0 and 20.1 nm. The movable fluid porosity is mainly distributed between 0.84 and 4.08%, with an average movable fluid porosity of 2.37%. The findings provide a theoretical basis for the efficient development of shale oil resources.

Preparation of carbon aerogel from waste newspaper for adsorption of antidiabetic drug residue from aqueous system

In this study, the waste newspaper was utilized to prepare carbon aerogel (CA) for adsorptive removal of Metformin hydrochloride (MH) (antidiabetic drug residues) from the aqueous system. The prepared CA was characterized using Field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) analyser. The MH adsorption was carried out using two types of water, one was laboratory-prepared distilled water and another was real river water. Although, optimum removal around 87 % was observed at pH 3, the removal efficiency at about 63 % estimated at neutral pH. In river water experiment, slightly lower rate of adsorption about 59 % was noticed. Nearly 61 % removal was found for 120 min and then no significant adsorption was found. The pseudo-second-order kinetics and Freundlich isotherm models presented a good interpretation of the adsorption experiment data. Physio-sorption was the primary mechanism of the MH adsorption was confirmed by Temkin and D-R isotherms studies. Regeneration studies demonstrated the removal stability of CA around 32 % until five cycles. An adsorption mechanism was also proposed for the removal of metformin hydrochloride using carbon aerogel.

Amino-functionalization of PVA/TiO2-CeO2 nanohybrid adsorbent for the removal of selenium ions from aqueous solutions: Equilibrium and kinetics studies

ABSTRACT In this study, a hybrid nanoadsorbent (HnA), (PVA/TiO2-CeO2), was synthesized and amino-functionalized by 3-aminopropyltriethoxysilane (APTES) to produce AHnA, for use in an advanced selenium adsorption study focusing on nonlinear equilibrium and kinetics models. AHnA was characterized using XRD, FTIR spectroscopy, SEM, and EDX elemental analyses, as well as BET-BJH techniques. According to the FTIR results, APTES has successfully cross-linked the PVA chain and introduced amine groups on the surface. Moreover, the modification resulted in an increase in the total pore volume from 0.0061 cm3/g in HnA to 0.021 cm3/g in AHnA. Several adsorption experiments were conducted to determine the impact of varying contact times within a pH range of 1 to 8 and concentrations ranging from 5 to 200 mg/L, using a One-Variable-At-a-Time (OVAT) procedure. Accordingly, a dosage of 2 g/L of modified nanocomposite exhibits optimal performance for removing selenium from a 20 mg/L solution at an acidic pH of 3 during 300 minutes of contact with selenium ions, while conforming to a pseudo-second-order kinetic model. The assessment of various nonlinear isotherm models for analyzing equilibrium data revealed that the experimental data of selenium adsorption conformed to a generalized isotherm, showing a maximum monolayer adsorption capacity of 17.643 mg/g.

Preparation and characterization of cauliflower-like γ-Fe2O3/H-γ-AlOOH magnetic composites with high adsorption performance towards As(V)

That long-term consumption of water with arsenic concentrations greater than 10 μg L−1 induces renal, hepatic, and cardiovascular diseases, in addition, the effective adsorbents for removing arsenic are limited by their harsh synthesis conditions, slow adsorption kinetics, low adsorption capacities and hard solid-liquid separation. Herein, a hierarchical cauliflower-like γ-Fe2O3/H-γ-AlOOH magnetic composites for the treatment of As(V)-contaminated wastewater is firstly proposed to avoid the complex centrifugation and filtration process, and achieve the purpose of simplifying operation. A series of physicochemical characterization tools reveal the successful synthesis of hierarchical cauliflower-like γ-Fe2O3/H-γ-AlOOH magnetic composite adsorbent with a large specific surface area (SBET) of 131.82 m2 g 1, high Zeta potential of +17.22 mV, and magnetic saturation (Ms) of 26.1 emu g−1, which synergistically improves the adsorption performance and achieve the purpose of simplifying operation. The related adsorption experimental data demonstrates that the saturated adsorption capacity for As(V) reaches 130.17 mg g−1 and decreases by only 17.6 % after six adsorption-desorption experiments, and the whole adsorption process conforms to Pseudo-second order model and the Langmuir model, which proves it is more inclined to be monolayer adsorption and there is no chemical reaction between As(V) and adsorbent. In addition, the adsorption of As(V) onto the cauliflower-like γ-Fe2O3/H-γ-AlOOH magnetic composites is assigned to a spontaneous, endothermic and entropy increased process. The main adsorption mechanism is that, combined with X-ray photoelectron spectroscopy (XPS) analysis, all components of the composite are involved in the adsorption of As(V), with the predominance of metal hydroxyl groups. The synthetic route of a novel and highly effective adsorbent, the hierarchical cauliflower-like γ-Fe2O3/H-γ-AlOOH magnetic composite material, provides a more promising alternative candidate for the As(V) treatment, from the perspective of aquatic ecosystem protection and solid-liquid separation.

New study of the adsorption mechanism of different dye molecules by high porous sludge activated carbon produced from a dairy-treatment effluent plant

In this study, a high-quality porous sludge-activated carbon from a dairy-treatment effluent plant in México (ACSDM) was produced, characterized, and investigated in the adsorption of 8 different dyes. The main focus was establishing how the dyes' molecular characteristics affect adsorption. So, the intrinsic characteristics of the different dye molecules were correlated with the experimental adsorption data. ACSDM proved high quality, considering their textural properties and physical-chemical characteristics. Adsorption was efficient using the natural pH of each dye solution and 1 g L−1 of ACSDM. The highest adsorption capacities were obtained in the following order: Methylene Blue (MB) (998.44 mg g−1), Crystal Violet (CV) (795.65 mg g−1), Fuchsine (F) (342.52 mg g−1), Direct Blue 86 (DB-86) (306.36 mg g−1), Alizarin Green (AG) (303.25 mg g−1), Reactive Black 5 (RB-5) (259.82 mg g−1), Methanil Yellow (MY) (252.81 mg g−1) and Amaranth Red (AR) (251.12 mg g−1). These results were obtained at 55 °C (endothermic process), except for MY, where the adsorption was exothermic (25 °C). Freundlich was the model that best fitted the DB-86, MB, and CV equilibrium data. While the Langmuir and Tóth models best fit the RB-5, AR, and MY isotherms. Tóth also best represented the F and AG data. Kinetic curves demonstrated that adsorption occurred faster for dyes MB, F, CV, MY, AR, and RB-5, respectively, reaching 90 %-99 % of their saturations in the first 30 minutes. Meanwhile, the adsorption of AG and DB-86 only about 85 % of the saturation occurred. The study indicated that molecular volume is the major variable in the dye adsorption process, as well as some individual chemical characteristics of the molecule.

High Surface Area Mesoporous Cotton Crop Biochar for Enhanced Confiscation of p-nitrophenol

This research study investigates the efficacy of utilizing biochar obtained from cotton crop residues for the enhanced remediation of p-nitrophenol (PNP). Cotton crop residue-derived biochar (CCB) was prepared using 1N phosphoric acid and subsequently characterized. Batch adsorption experimental analysis were conducted to assess the optimal adsorption capacity of CCB for PNP under various conditions, including temperature, pH, interaction time, initial PNP concentration, and dosage of biochar. The results demonstrated optimal adsorption capacity of 55.38 mg/g at pH 5.0, initial PNP concentration of 100 mg L-1 , and biochar dosage of 200 mg at a room temperature of 298 K. The experimental adsorption data exhibited an excellent correlation with the Redlich-Peterson isotherm model. Analysis of the sorption kinetics revealed that the material's uptake behavior closely followed a pseudo-second-order model. Thermodynamics analysis unveiled that the adsorption of PNP onto CCB was exothermic, spontaneous, and primarily driven by enthalpy. Overall, the findings suggest that CCB exhibits promising potential as an efficient adsorbent for the remediation of aquatic environments afflicted with presence of PNP.

Optimizing methylene blue adsorption conditions on hydrothermally synthesized NaX zeolite through a full two-level factorial design.

Besides being hazardous to humans and aquatic organisms, dyes present in water reservoirs limit sunlight's availability to aquatic plants and animals, making significant impact on their growth and development. Herein, the adsorptive removal of methylene blue (MB) dye from aqueous solution using type X (NaX) zeolite by full experimental design 2 n was studied. The physical and chemical properties of NaX zeolite were identified using various characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray (SEM-EDS), Fourier transform infra-red (FT-IR), and Brunauer-Emmett-Teller (BET) surface area analyses. Results confirmed that NaX zeolite had a cubic shaped crystalline structure with 2-4 μm size and high (375 m2 g-1) specific surface area, having 90% optimal adsorption efficiency. Langmuir and Elovich isotherm models were best fitted to adsorption experimental data and a pseudo-second-order kinetic model describes well the adsorption kinetic data. Akaike information criteria (AIC) was used to assess the best fitted models on the experimental data. A thermodynamic study reveals that the MB adsorption onto NaX was exothermic, spontaneous, and feasible.

Date kernel biochar: A green approach to methylene blue removal from polluted water in Iraq

ABSTRACT This study investigated the potential use of biochar produced from Iraqi date kernels (Khestawi) as an adsorbent for methylene blue (MB) removal from polluted water. A full factorial design methodology was employed to examine the effects of heating rate, pyrolysis temperature and holding time on the performance of the produced biochar. The results showed that pyrolysis temperature and time had a strong effect on the biochar performance, while the heating rate had a weaker effect. The biochar produced at pyrolysis temperatures of 350°C and 550°C exhibited MB removal percentages (% R) of 48.9% and 30.9%, respectively. Similarly, biochar production through pyrolysis durations of 30 and 90 minutes resulted in MB removal rates of 47.5% and 30.3%, respectively. The adsorption experimental data was well-fitted by the Freundlich isotherm model, with a high value of the Freundlich constant (KF = 1.64), indicating a high adsorption capacity of the biochar. The activation of biochar using bio-oil (organic-1) led to a substantial enhancement in the adsorption capacity, with the activated biochar (ABC-1) exhibiting a higher adsorption capability and a higher value of the Freundlich constant (KF = 7.12). Overall, the results suggest that biochar produced from date kernels has the potential as an effective and sustainable adsorbent for MB removal from polluted water, with the potential for further enhancement through biochar activation.

A mat based on PVA doped with TiO2 nanoparticles for removal of methylene blue dye from aqueous solution and improving the carbon footprint.

Water supply is the great challenge for climate change and overpopulation. A Nanofiber mat consisting of Poly vinyl alcohol (PVA), nanoTiO2, and citric acid (PTC) was prepared using an electrospinning technique at a constant flow rate (0.5 ml/h). The morphology of the mat was detected using (FESEM) technique and image J software; they show that the mat has a Nanofiber morphology with an average diameter of 170 nanometers. This mat was used to remove methylene blue (MB) from water in two ways, the adsorption process and by photodegradation using UV light. The kinetic study of the adsorption of methylene blue MB on a PTC mat was carried out. results show that the pseudo-second order is best to describe the adsorption, of MB and the Intra- particle diffusion is the rate determining step. Seven isotherm models; four of two-parameters and three of three-parameters were used to examine the adsorption experimental data by applying linear and non-linear regression method using six error functions. The results showed comparable data between linear and non-linear regression methods for two parameters isotherms, and the best isotherm fitting with the data were Freundlich and Temkin models. On the contrary, three parameters isotherms showed distracted data between linear and non-linear regression methods. In addition, the results appear that the best predictive error function was ꭓ2.

Effect of Photoaging on Adsorption of Cu(Ⅱ) by Polystyrene Microplastics with Different Particle Sizes

In order to evaluate the effect of aging and particle size on the adsorption of heavy metals by microplastics, the adsorption behavior of Cu(Ⅱ) by three different particle sizes of polystyrene (PS; 1, 50, and 100 μm) under UV irradiation was systematically studied. The results demonstrated that UV aging significantly changed the surface morphology and physicochemical properties of PS, and 1 μm PS had the strongest aging degree. The adsorption kinetics of PS on Cu(Ⅱ) conformed to the pseudo-second-order kinetic model, and the Freundlich model was more suitable for the experimental data of isothermal adsorption of Cu(Ⅱ) by PS. These results indicated that the adsorption of Cu(Ⅱ) by PS occurred on the non-uniform surface of PS, and the adsorption behavior was multilayer adsorption. Parameter "n" of the Freundlich model was less than 1, indicating that the adsorption behavior of PS on Cu(Ⅱ) was a higher intensity physical adsorption behavior. The order of theoretical maximum adsorption capacity of different particle sizes PS for Cu(Ⅱ) was as follows:1 μm > 50 μm > 100 μm, indicating that the size of PS was an important influence factor for the adsorption capacity of PS to pollutants. For the same particle size PS, aging enhanced its adsorption capacity for Cu(Ⅱ). The results on the adsorption of Cu(Ⅱ) by PS under different environmental conditions indicated that the adsorption capacity of PS for Cu (II) increased with the increase in pH, whereas an increase in salinity had the opposite effect. Surface complexation and electrical adsorption were the main mechanisms of adsorption of Cu(Ⅱ) by PS. This study provides an important scientific basis for understanding the adsorption behavior of microplastics to heavy metals in the environment.

Development of a novel MIL‐68‐NH2@MCC composite for enhanced and synergistic removal of methylene blue and Sm(III) from an aqueous environment

In this study, a pioneering composite material, MIL‐68‐NH2@MCC, was synthesized by integrating an indium‐based metal–organic framework (MIL‐68‐NH2) with microcrystalline cellulose (MCC), that could be prepared by recycling different natural products of cellulose. The surface characteristics of the novel MIL‐68‐NH2@MCC composite were meticulously examined through X‐ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy‐dispersive X‐ray spectroscopy (EDX). Remarkably, MIL‐68‐ NH2@MCC demonstrated significantly improved efficiency in removing methylene blue (MB) dye and Sm(III) ions from aqueous solutions, surpassing the removal capabilities of its individual constituents, MIL‐68‐NH2 and MCC. This superior performance can be attributed to the synergistic interplay between MIL‐68‐ NH2 and MCC. We thoroughly investigated the influence of various parameters, including pH, contact time, initial concentration, and temperature. The experimental adsorption data for both MB and Sm(III) exhibited a good fit with the Langmuir isotherm model. The optimized MIL‐68‐NH2@MCC exhibited remarkable maximum adsorption capacities of 133.8 mg/g for MB and 72.1 mg/g for Sm(III). The adsorption kinetics followed a pseudo‐second‐order model with correlation coefficients of 0.9879 and 0.9875 for MB and Sm(III), respectively. The application of intraparticle diffusion and the Boyd kinetic models demonstrated that the film diffusion is the dominant factor influencing the rate of the adsorption process. The study also examined a possible mechanism for the adsorption of MB and Sm(III) on the optimized MIL‐68‐NH2@MCC surface. Ultimately, the results highlight the originality of our research in terms of the efficacy of the newly developed MIL‐68‐NH2@MCC composite as an eco‐friendly adsorbent. Besides, the developed adsorbent effectively removes MB and Sm(III) from different water solutions while exhibiting outstanding selectivity and reusability.

Adsorptive removal of phosphate from aqueous solutions using FeCl3‐immobilized melamine‐formaldehyde‐urea resin

AbstractThe surplus phosphorus in aquatic environments trigger eutrophication, an irreversible pollution stage marked by the rapid growth of algae and water plants, a decline in dissolved oxygen levels, and the emergence of dead zones. To address this critical issue, this study focuses on the removal of phosphorus in form of phosphate from aqueous solutions. The research involves the synthesis and characterization of FeCl3‐immobilized melamine‐formaldehyde‐urea resin, an innovative adsorbent, its characterization through Fourier transform infrared spectroscopy, and the evaluation of its adsorption capacity based on Langmuir and Freundlich equilibrium models. The experimental adsorption data fits well with pseudo‐second order kinetic model. Optimal adsorption parameters are carried with batch adsorption technique for 60 min using 0.5 g of adsorbent at pH = 2, achieving 15.55 mg g−1 adsorption capacity, and conducting experiments with tap‐water samples to replicate real‐world scenarios. The research findings have the potential to advance sustainable wastewater treatment technologies and contribute to the mitigation of nutrient pollution in aquatic ecosystems, addressing a pressing environmental concern.

Syzygium aromaticum-mediated green synthesis of iron oxide nanoparticles for efficient heavy metal removal from aqueous solutions

The current study focused on the environmentally friendly synthesis of iron oxide nanoparticles (IONPs) using ferric nitrate Fe(NO3)3 9H2O as a precursor and aqueous Syzygium aromaticum (clove) extract as a reducing agent. Several analytical methods, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and ultraviolet–visible (UV–Vis.) spectroscopy, were used to confirm the synthesized iron oxide nanoparticles. These procedures were carried out to learn more about the surface shape and chemical composition of the produced iron oxide nanoparticles. The mean size of iron nanoparticles was determined by TEM examination to be 4.7 nm. The characterization revealed that the primary component of iron nanoparticles was magnetite when the Syzygium aromaticum extract was utilized as a reducing agent for Fe3+. For application, synthesized material was used to remove the harmful Cr (VI) ions from an aqueous solution. The batch adsorption approach was utilized to maximize the effects of significant elements such as pH, adsorbent dose, treatment duration, and initial Cr (VI) ions concentration to achieve the highest removal of Cr (VI) ions. The experimental adsorption data were fitted using various isotherm and kinetic adsorption models.