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In this study, three different types of biochar (biomass materials were beech wood, corncob, and bamboo) were loaded with bismuth to form bismuth impregnated biochars (named respectively as Bi@WBC, Bi@CBC, and Bi@BBC) to investigate their properties (pore structure and surface chemistry characteristics) on methylene blue (MB) removal capacities. Three bismuth impregnated biochars made from different biomass materials were ranked for their adsorption capacity of MB as follows: Bi@WBC > Bi@CBC > Bi@BBC, in which Bi@WBC showed the largest Langmuir adsorption capacity of 178.59 mg g−1. While the specific surface area (SSA) and pore volume of Bi@WBC were the largest (accounting for 477.74 m2 g−1 and 0.15 cm3 g−1, respectively), according to the FTIR and XPS results, Bi@WBC (72.3%) exhibited a higher proportion of BiO bonds than the Bi@CBC (52.3%) and Bi@BBC (48.4%) did. Conclusively, the rich porous structure and surface functional groups of Bi@WBC affected the adsorption capacity of MB, and the chemical adsorption provided the main contribution. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Based on the excellent performances of nanocrystalline cellulose, sodium alginate, or K-carrageenan in Pb2+ adsorption, nanocrystalline cellulose/sodium alginate/K-carrageenan composite hydrogel beads were prepared to adsorb Pb(II) from aqueous solutions. The objective of this study was to demonstrate the excellent potential of the composite hydrogel beads for heavy metal ion adsorption. We successfully prepared ecofriendly Fe-modified nanocrystalline cellulose/sodium alginate/K-carrageenan composite hydrogel beads and characterized them. The structure and adsorption mechanism were investigated using scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy, and the optimal adsorption conditions were determined. The tricomponent hydrogel beads were robust and exhibited improved adsorption capacity for Pb2+ and good reusability. The adsorption results could be fitted well with a pseudo-second-order kinetic model and the Langmuir adsorption model. The maximum adsorption capacity obtained by fitting was 351.04 mg g−1. Recycling experiments revealed that the adsorption capacity of the adsorbent remained high after five cycles of reuse. [ABSTRACT FROM AUTHOR]

The performance of Fe 3 O 4 /attapulgite (APT) nanoparticles in Pb(II) adsorption from aqueous solutions could be improved by modifying the particles with aminopropyltriethoxysilane (APTS) and then combining with chitosan (CS) into beads. After preparing the APTS-Fe 3 O 4 /APT@CS beads, their surface morphology and crystal phases were analyzed by Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. The magnetic properties of APTS-Fe 3 O 4 /APT@CS were studied by a vibrating sample magnetometer, while their heat resistance and stability were characterized by thermal weight analysis. A recycling test and comparison of adsorption capacities were also carried out. The adsorption capacity of Fe 3 O 4 /APT was improved by the modification with APTS and CS. The adsorption process conforms to the pseudo-second-order kinetic and Langmuir adsorption isotherm models. The adsorption of Pb(II) reaches a maximum of 625.34 mg/g, which compares favorably with other reported adsorbents. The results show that APTS-Fe 3 O 4 /APT@CS is a promising hybrid adsorbent for effective removal of Pb(II) from water. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ionic liquid [BMIM][PF6] has been encapsulated in polysulfone. [•] The microcapsules containing ionic liquid have been used for the first time to extract caprolactam from water. [•] The adsorption kinetics and sorption isotherm have also been discussed. [ABSTRACT FROM AUTHOR]

Chitosan modification is an important method for the development of adsorbents that has attracted considerable interest in recent years. In this regard, a new type of efficient Pb(II) adsorbent was prepared in a simple and cost-effective way. In this study, carboxylated chitosan (CYCS) and carboxylated nanocellulose (CNC) were used to chelate and synthesize hydrogel spheres with effective adsorption sites, in calcium chloride solution. The prepared carboxylated chitosan/carboxylated nanocellulose (CYCS/CNC) hydrogel beads were used as Pb(II) adsorbents, and using scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy, the structure and adsorption properties of the prepared beads were investigated. The CYCS/CNC adsorbents exhibited an excellent aqueous Pb(II) adsorption capacity (q m = 334.92 mg g−1), and the experimental results further revealed that the adsorption data fitted well with the Langmuir model, and the adsorption kinetics accorded with the pseudo-second-order model. Additionally, the adsorption mechanism was identified as monolayer chemisorption. Unlabelled Image • Efficient and economic CYCS/CNC composite is prepared for Pb(II) adsorption. • CYCS/CNC exhibits excellent aqueous Pb(II) adsorption capacity (Qm = 334.92 mg g−1). • Adsorption mechanism of CYCS/CNC includes chemical and electrostatic adsorption. • The adsorption performance is good even after four regeneration cycles. [ABSTRACT FROM AUTHOR]

Composite adsorption materials combine the advantages of various adsorptive materials and compensate for the defects of single adsorbents. Magnetic montmorillonite (MMMT) shows good adsorption properties for Pb(II). In order to further improve the adsorption properties of MMMT, in this work, Zn-BDC, a kind of metal–organic framework (MOF), was modified onto the surface of MMMT by in situ polymerization. The composite material MMMT@Zn-BDC was characterized by Zetasizer, SEM, TEM, FTIR, XRD, VSM, and XPS. The influence of adsorption conditions on the adsorption capacity of MMMT@Zn-BDC for Pb(II) was examined, including the adsorbent dosage, pH of Pb(II) solution, initial concentration of Pb(II), and the temperature and adsorption time. Also, the adsorption mechanism was studied. The results of this study show that MMMT@Zn-BDC adsorbs Pb(II) via chemisorption. In addition, MMMT@Zn-BDC exhibits good potential for adsorbing Pb(II), including its high adsorption capacity (724.64 mg/g) and good recyclability. [ABSTRACT FROM AUTHOR]

In this work, a tetraethylenepentamine (TEPA)-grafted metal-organic framework material (MIL-101) was synthesized. The introduction of TEPA increased the abundance of functional groups on the MIL-101. As a powdery adsorbent, MIL-101-TEPA can be difficult to separate. In order to solve this problem, we combined MIL-101-TEPA with sodium alginate (SA) and injected the mixture into a CaCl2 solution to solidify the powder into beads with a particle size of 3 mm. The easily recovered adsorbent was applied to the adsorption of Pb(II) from water. The structure and characterization of the adsorbent were investigated through scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), X-Ray diffraction (XRD), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). We also optimized the adsorption conditions. The results of the study showed that the adsorption process was chemisorptive and endothermic in nature. The maximum adsorption capacity of the composite beads was 558.6 mg/g. Meanwhile MIL-101-TEPA@CA showed good repeatable utilization. [ABSTRACT FROM AUTHOR]

Diclofenac sodium (DS) is an emerging contaminant that is toxic and remains at high concentrations in natural aquatic environments. The aim of this study was to fabricate a novel spherical polymeric adsorbent composed of cross-linked chitosan beads grafted by polyethylenimine (PEI) to remove DS from water. The adsorbents were thoroughly characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, elemental analyses, and X-ray photoelectron spectroscopy. A cross-linking step was expected to enhance adsorption. The experimental data obtained from a series of adsorption experiments were fit well by the Langmuir isotherm model and pseudo-second-order model. The epichlorohydrin–PEI adsorbent (EPCS@PEI) showed a maximum adsorption capacity of 253.32 mg/g and removal efficiency of nearly 100% for the DS in the initial 50 mg/L solution. Therefore, EPCS@PEI is proposed as a potential adsorbent for DS removal, where these initial findings are expected to promote further design and fabrication of effective adsorbents for practical applications. [ABSTRACT FROM AUTHOR]

Groundwater contaminated by arsenic endangers our health. Therefore, in this work, a novel composite adsorbent consisting of magnetic chitosan (MCS), zinc oxide (ZnO), and sodium alginate (Alg) was prepared to remove arsenic from groundwater. First, chitosan was coated on the surface of Fe 3 O 4 nanoparticles by coprecipitation. Then, MCS/ZnO@Alg gel beads were fabricated by combining MCS with ZnO and Alg, and crosslinking the composite material in the presence of Ca2+ ions. The MCS/ZnO@Alg beads were characterized by SEM, FTIR spectroscopy, XRD, VSM, and XPS. The adsorption experiments revealed that the MCS/ZnO@Alg magnetic gel beads have high stability and As(V) adsorption capability, and adsorbed As(V) through chemical adsorption. The maximum As(V) adsorption capacity as determined from the Langmuir model was 63.69 mg/g. In addition, MCS/ZnO@Alg exhibited good recyclability and high sustainability. This work proves that the MCS/ZnO@Alg gel beads are an ideal candidate for addressing the grievous environmental threats caused by water pollution. [ABSTRACT FROM AUTHOR]

A novel ethylenediaminetetraacetic acid (EDTA)-functionalized magnetic chitosan oligosaccharide and carboxymethyl cellulose (Fe 3 O 4 @CMCCOS-EDTA) nanocomposite adsorbent was successfully fabricated for Pb(II) adsorption. The adsorbent was characterized by Fourier transform infrared, and X-ray photoelectron spectroscopy was used to confirm successful EDTA modification and Pb(II) adsorption. Scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometer, and thermogravimetric analysis were used to study the morphology and properties of magnetic particles. EDTA modification considerably improved the capacity of the adsorbent. The batch adsorption experiment results indicated that the pseudo-second-order (PSO) model and the Langmuir isotherm model reliably described the adsorption behavior. The maximum adsorption capacity (q m) for monolayer chemical adsorption was calculated to be 432.34 mg/g at the pH of 5 and temperature of 308 K. Notably, Fe 3 O 4 @CMCCOS-EDTA exhibited a high Pb(II) removal rate of ~100% using an initial metal ion solution of 100 mg/L and 200 mg/L. [ABSTRACT FROM AUTHOR]

• Novel composite based on polyacrylic acid and magnetic chitosan was carried out. • Magnetic composite shows an efficient removal ratio for Pb(II). • Magnetic composite remove Pb(II) efficiently. • Magnetic composite is well tolerated under acidic conditions. A creative combination of chitosan with polyacrylic acid (PAA) improves the acidity resistance of chitosan and increases its potential in the field of adsorption. In order to facilitate recovery, magnetic nanoparticles were incorporated in CS–PAA to obtain a magnetic-CS–PAA (MCS–PAA) nanocomposite. The physical and chemical characteristics of the composite adsorbent MCS–PAA were determined by SEM, TEM, FTIR, EDX, XRD, and XPS. This environmental-friendly, magnetic, composite adsorbent showed significantly better adsorption performance than those of the individual adsorbents alone. The maximal adsorption capacity was 204.89 mg/g according to the Langmuir isotherm model, when the concentration of Pb(II) was 100 mg/L at the equilibrium time of 70 min. The main adsorption mechanism was the complexation between the carboxyl, amino, and hydroxyl groups in MCS–PAA and Pb(II). Further, introduction of PAA also improved the acid resistance of CS. The new adsorbent MCS–PAA is thus expected to facilitate a wider range of applications for chitosan in the adsorption of Pb(II). [ABSTRACT FROM AUTHOR]

We synthesized composite microspheres from cellulose nanocrystal (CNC), polyvinyl alcohol (PVA), and sodium alginate (SA), which were modified with polyethyleneimine (PEI) to introduce a high density of active amino sites onto the surface via the Schiff base reaction. We hypothesized that these (SA/CNC/PVA)@PEI microspheres would have a high adsorption capacity for aqueous diclofenac sodium (DS). The PEI-modified composite microspheres were characterized and assessed and optimized for aqueous DS adsorption. In addition, the morphology and synthesis mechanism of the adsorbent were studied. The adsorption process showed a good fit with the pseudo-second-order kinetic model (i.e., the process is driven by a chemical adsorption mechanism) and Langmuir adsorption isotherm model (i.e., adsorption follows a single-layer process). Under the optimum experimental conditions (pH: 4.5, adsorption time: 50 min, temperature: 303 K), the maximum adsorption capacity was 418.4104 mg/g, which was relatively high compared to other reported adsorbents. Importantly, after five adsorption–desorption cycles, (SA/CNC/PVA)@PEI showed only a slight loss in adsorption capacity. Compared with other reported adsorbents, the core–shell composite has a good DS adsorptive capacity and high recyclability. [ABSTRACT FROM AUTHOR]

In this work, composite hydrogel beads based on magnetic bentonite/carboxymethyl chitosan/sodium alginate (Mag-Ben/CCS/Alg) were fabricated and their ability to adsorb copper ions in water was studied. The structure and properties of the composite were characterized via SEM, FTIR, XPS, TGA, VSM, and Zeta potential tests. The effects of the adsorbent dosage, adsorption time, pH, temperature, and initial concentration of Cu(II) on the adsorption results were studied. The results showed that Mag-Ben/CCS/Alg reached equilibrium after 90 min of adsorption, the removal rate of Cu(II) was 92.62 ± 0.39%, and the maximum adsorption capacity was 56.79 mg/g (30 °C). The removal rate of Cu(II) by Mag-Ben/CCS/Alg still remained above 80% after recycling four times. The adsorption process of Cu(II) by Mag-Ben/CCS/Alg occurred in accordance with the quasi-second-order kinetic model and Langmuir adsorption isotherm. The adsorption process was spontaneous and endothermic. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Cellulose nanocrystals-chitosan composite double functionalized with amino group to enhance adsorption. • Diclofenac sodium adsorbed via acid-base interaction between carboxyl and amino groups. • The adsorption capacity of CNC-ED@CS-ED is remarkable high. • CNC-ED@CS-ED exhibited good reusability. Abstract Residual diclofenac sodium (DS) in the environment is harmful to human health. A promising method for DS removal is the use of adsorbents functionalized with amino groups that can form an ionic bond with the carboxyl group of DS at a suitable pH. In this work, a novel composite adsorbent composed of cellulose nanocrystals (CNC) and chitosan (CS) has been synthesized and functionalized by ethylenediamine (ED) in both layers. Characterization methods, including scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectrometry, and X-ray photoelectron spectroscopy, were used to confirm the morphology and synthetic mechanism of the double- amino-functionalized adsorbent. Based on the optimization of adsorption conditions and modeling of the adsorption mechanism, the DS adsorption process on CNC-ED@CS-ED involves chemical adsorption, and the maximum adsorption capacity obtained from the Langmuir model is 444.44 mg/g. CNC-ED@CS-ED exhibits good adsorption capacity and high sustainability; thus, it is a promising composite material for the removal of DS from wastewater. [ABSTRACT FROM AUTHOR]

Abstract In this study, we prepared a magnetic composite based on amine-functionalized chitosan (aminochitosan; AmCS) and Fe 3 O 4 to remove diclofenac sodium (DS) from water. The fabricated AmCS@Fe 3 O 4 composite was characterized using Fourier-transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, vibrating sample magnetometry, X-ray diffraction, and thermogravimetric analysis. Furthermore, we investigated the influence of pH, initial DS concentration, and adsorbent dosage on the adsorption of DS. Through thermodynamic analysis, we found that the data corresponded with the Langmuir adsorption isotherm model. The maximum adsorption capacity reached 469.48 mg g−1, and the adsorption process followed the pseudo-second-order kinetic model. Finally, the AmCS@Fe 3 O 4 composite retained good adsorption characteristics after four consecutive cycles, with removal efficiency exceeding 70%. Therefore, the developed adsorbent could be used for efficient adsorptive removal of trace drugs and personal care products from water bodies. Graphical abstract Image 1 Highlights • AmCS@Fe 3 O 4 composite was successfully synthesized and characterized. • AmCS@Fe 3 O 4 composite was applied for adsorption of diclofenac sodium from water. • Maximum adsorption capacity of AmCS@Fe 3 O 4 was 469.48 mg g−1. • The experimental data have been tested using isotherm and classical kinetic models. [ABSTRACT FROM AUTHOR]

In the present study, a new adsorbent based on carboxylated cellulose nanocrystal (CCN) was developed for the adsorption of Pb(II) from fish sauce. The prepared adsorbent material was characterized by zeta potential, FT-IR, XRD, and XPS tools. The changes in the morphological structure of the developed CCN surface were evidenced by SEM and TEM. The favorable adsorption conditions were selected by studying the contact time, initial concentration, temperature, and concentration of the used glutamic acid and NaCl. The results indicated that the Langmuir isotherm model agrees very well with experimental adsorption data ( R 2 = 0.9962) with a maximum adsorption capacity 232.56 mg/g of Pb(II) at 293.2 K. Additionally, data of the adsorption kinetics follow the pseudo-second-order kinetics ( R 2 > 0.9990). On the other hand, the thermodynamics studies show that the adsorption process is spontaneous and endothermic. Furthermore, the developed CCN could be regenerated using acid treatment with a good reusability for Pb(II) adsorption. The results clearly indicated that the synthesized CCN could be effectively applied as a new material for Pb(II) adsorption from fish sauce solutions. [ABSTRACT FROM AUTHOR]

Chitosan (CS)—a natural macromolecule—exhibits various limitations, such as difficult recovery, low mechanical strength, and low adsorption capacity. In this work, to address these shortcomings, polyvinyl alcohol (PVA) was mixed into chitosan beads, thereby improving the mechanical strength and acid resistance of CS. Following this, ethylenediamine tetraacetic acid (EDTA) was introduced to the surface of the mixed beads to fabricate PVA-CS-EDTA, a functionalized adsorbent. Series characterization methods are employed to study the surface morphology, chemical groups, and adsorption strengths of the adsorbents. Moreover, the effects of various adsorption conditions on Cu(II) adsorption are studied. According to the results, the adsorption of Cu(II) by the adsorbent beads follows pseudo-second-order kinetics and the Langmuir adsorption isotherm model. The maximum adsorption capacity of PVA-CS-EDTA is 127.81 mg/g, which is substantially higher than that of the CS beads. In addition, the PVA-CS-EDTA beads remain structurally intact even after treatment with an acidic solution (pH = 2). The higher adsorption capacity and acid resistance of the developed CS are promising for wide applications in the field of adsorption. • EDTA modified PVA-CS composite beads were prepared. • The composite beads showed an excellent acid resistance and adsorption capacity for Cu(II). • The effects of various adsorption conditions on the adsorption of Cu(II) are studied. [ABSTRACT FROM AUTHOR]

• A core shell/bead-like PVA/CS/SAP@PEI was fabricated for diclofenac sodium removal. • Adsorbent exhibits excellent adsorption capacity ascribed to the sufficient amino. • Mechanical stability of the beads is guaranteed by nanofillers and PEI coating. • It is easily separated after adsorption in aqueous solution and is recyclable. Residual diclofenac sodium (DS) in water is a potential hazard. The electrostatic attraction between amino group of adsorbents and carboxyl group of DS under acidic conditions can effectively remove DS from water. Herein, a novel core–shell adsorbent of poly(vinyl alcohol)/chitosan/amino-grafted silica@polyethylenimine (PVA/CS/SAP@PEI) gel bead was prepared to efficiently uptake DS from wastewater. In this study, the gel bead was characterized using FTIR, XPS, SEM, EDS, and 13C NMR. The experimental data shows that there is a strong correlation between adsorption capacity. The adsorption data fitted well with the Freundlich isotherm model and the pseudo-second-order model. The results of thermodynamics show that the adsorption process is spontaneous, endothermic, and increases entropy. The maximum adsorption capacity for DS was calculated as 493.81 mg/g at pH 5 (308 K). The adsorbent still exhibited excellent adsorption capacity after recycling five times, showing it has excellent potential for practical applications. [ABSTRACT FROM AUTHOR]