Cross-linked Beads Research Articles

Cross-linked chitosan/pencil clay hybrid beads for the adsorption of reactive black 5

Chitosan (CH) and pencil clay (CL) were utilized to prepare stable epichlorohydrin cross-linked chitosan-clay hybrid beads (CCHB) for the adsorptive removal of anionic reactive black 5 (RB5) dye. Among various percentage weight ratios of chitosan/clay hybrid beads, 40 % CH–60 % CL was selected as the best adsorbent owing to its stability and removal efficiency. The pore properties of CCHB in terms of surface area, total pore volume, and average pore width were 40.33 m2/g, 0.088 cm3/g, and 86.06 Å, respectively. The adsorption behavior of RB5 on CCHB followed Langmuir and pseudo-second-order models. Thermodynamic parameters confirm the endothermic and spontaneous nature of RB5 adsorption and the regeneration studies reveal a negligible decrease in removal efficiency of CCHB after 5 adsorption-desorption cycles. The CCHB exhibited adsorption capacities of 169.49, 200.00, and 227.27 mg/g for RB5, respectively, at 30, 40, and 50 °C. The prepared chitosan-clay hybrid bead adsorbent can be efficiently applied for anionic wastewater treatment.

Biodegradable CMC/ZnO/Ni Cross-Linked Hydrogel Beads for Enhanced Plant Growth and Increased Soil Urease Activity

Biodegradable CMC/ZnO/Ni Cross-Linked Hydrogel Beads for Enhanced Plant Growth and Increased Soil Urease Activity

Sustainable pretreatment method of lignocellulosic depolymerization for enhanced ruminant productivity using laccase protein immobilized agarose beads

Laccase, the selectively lignin degrader, vital to the initiation of lignocellulosic deconstruction was immobilized onto activated agarose beads to increase its reuse potential. Laccase cross-linked beads (~ 3.42 mm) recorded a specific activity of 23 Umg− 1, retaining about 80.43% enzyme activity after 45 days of storage. The immobilization yield and efficiency were 89% and 97% respectively. The equilibrium data fitted the Freundlich equation (R2 = 0.9987) demonstrating multilayer adsorption and the presence of Cu, Fe, and S in the elemental analysis of immobilized beads established effective binding between activated agarose beads and the laccase protein. Characterization studies of the immobilized laccase-treated crop residues revealed significant differences in the lignin polymer after each treatment cycle. An increase in digestibility of 26.21% and 7.62% was observed in paddy and finger millet-treated straws respectively, over the controls corroborating efficient lignin depolymerization. The propitious performance of laccase beads authenticated in the batch enzymatic reactor to treat crop residues paves headway as a sustainable green technology in the deconstruction of crop residues for use as ruminant feed, augmenting productivity.

Fabrication, characterization and transdermal properties of double cross-linked gel beads with 4-n-butylresorcinol

In this paper, sodium alginate (SA) -agarose double cross-linked gel beads were prepared to improve the solubility of 4-n-butylresorcinol and to reduce skin irritation. The wrappage material suitable for 4-nBR gel beads was SA-agarose double cross-linking material, and the internal inclusions were in the form of 4-n-butylresorcinol nanoemulsions (4-nBR NEs). Under the orthogonal fluorescence microscope, it was observed that the gel beads were spherical in shape, with smooth and rounded surfaces and permeable interiors. The encapsulation rate of the gel beads was 84.37 ± 3.56 %, and the average diameter was 1.93 ± 0.21 mm. Scanning electron microscopy showed that the gel beads were spherical in shape. The cumulative leakage rate of the gel beads on the 35 th day was 4.72 ± 0.06 %, suggesting that the gel beads encapsulated 4-butylresorcinol to good effect and with high stability. This proves that the gel beads wrapped with 4-nBR are highly effective and stable. In vitro skin permeability assessment verified the good skin permeability of nanoemulsions (NEs).

Synthesis of agro-industrial wastes/sodium alginate/bovine gelatin-based polysaccharide hydrogel beads: Characterization and application as controlled-release microencapsulated fertilizers

Synthesis of novel agro-industrial wastes/sodium alginate/bovine gelatin-based polysaccharide hydrogel beads, micromeritic/morphometric characteristics of the prepared formulations, greenhouse trials using controlled-release microencapsulated fertilizers, and acute fish toxicity testing were conducted simultaneously for the first time within the scope of an integrated research. In the present analysis, for the first time, 16 different morphometric features, and 32 disinct plant growth traits of the prepared composite beads were explored in detail within the framework of a comprehensive digital image analysis. The hydrogel beads composed of 19 different agro-industrial wastes/materials were successfully synthesized using the ionotropic external gelation technique and CaCl2 as cross-linker. According to micromeritic characteristics, the ionotropically cross-linked beads exhibited 77.86 ± 3.55 % yield percentage and 2.679 ± 0.397 mm average particle size. The dried microbeads showed a good swelling ratio (270.02 ± 80.53 %) and had acceptable flow properties according to Hausner's ratio (1.136 ± 0.028), Carr's index (11.94 ± 2.17 %), and angle of repose (25.03° ± 5.33°) values. The settling process of the prepared microbeads was observed in the intermediate flow regime, as indicated by the average particle Reynolds numbers (169.17 ± 82.81). Experimental findings and non-parametric statistical tests reveal that dried fertilizer matrices demonstrated noteworthy performance on the cultivation of red hot chili pepper plant (Capsicum annuum var. fasciculatum) according to the results of greenhouse trials. Surface morphologies of the best-performing fertilizer matrices were also characterized by Scanning Electron Microscopy. Moreover, the static fish bioassay experiment confirmed that no abnormalities and acute toxic reactions occurred in shortfin molly fish (Poecilia sphenops) fed with dried leaves of red hot chili pepper plants grown with formulated fertilizers. This study showcased a pioneering investigation into the synthesis of microcapsules using synthesized hydrogel beads along with digital image processing for bio-waste management and sustainable agro-application.

Engineering Thermo/pH-Responsive Lactoferrin Nanostructured Microbeads for Oral Targeting of Colorectal Cancer.

Colorectal cancer is an extremely aggressive form of cancer that often leads to death. Lactoferrin shows potential for targeting and treating colorectal cancer; however, oral delivery faces hurdles hampering clinical applications. We engineered dual-responsive lactoferrin nanostructured microbeads to overcome delivery hurdles and enhance drug targeting. The hydrophobic drug mesalazine (MSZ) was coupled to lactoferrin to form amphiphilic conjugate nanoparticles, dispersed in water. The lipid-soluble polyphenolic drug resveratrol (RSV) was then encapsulated into the hydrophobic core of LF-MSZ nanoparticles. To impart thermoresponsive properties, the dual-payload NPs were coupled with a PNIPAAm shell; finally, to further endow the nanoparticles with gastrointestinal resistance and pH responsiveness, the nanoparticles were microencapsulated into ionically cross-linked pectin-alginate beads. The nanoparticles showed enhanced internalization and cytotoxicity against HCT colon cancer cells via LF-receptor-mediated endocytosis. Thermal triggering and tuned release were conferred by the temperature-sensitive polymer. The coatings protected the drugs from degradation. Orally delivered microbeads significantly reduced tumor burden in a mouse colon cancer model, lowering carcinoembryonic antigen and elevating antioxidant enzymes. Apoptotic pathways were stimulated, indicated by heightened Bax/Bcl2 ratio and caspase-3/9 expression. Overall, we propose the innovative lactoferrin nanostructured microbeads as a paradigm shift in oral colorectal cancer therapeutics.

Simple and modified chitosan gel beads from a natural source as a bio-sorbent for water defluoridation: Experimental and computational perspectives

Water contaminated with fluoride (F -) is widely acknowledged as a major global issue that poses serious health and environmental risks. Adsorption is one of the many fluoride removal treatment methods that has been widely and successfully investigated. In this work, we describe a simple process for making both cross-linked and uncross-linked chitosan gel beads from shrimp waste. SEM, FTIR, XRD and TGA analysis confirmed the successful synthesis of the non-cross-linked chitosan gel beads (Cs beads) and cross-linked chitosan gel (Cs-Ech beads) whose swelling behavior, stability and fluoride removal efficiency were studied. The adsorption conditions were also optimised. An adsorption capacity of 16.59 mg/g was achieved after just 30 min and at pH = 6.8, 10 mg/L and T = 25 °C. It was shown that chitosan gel beads cross-linked with epichlorohydrin removed more fluoride than non-cross-linked chitosan gel beads. The rate of adsorption of fluoride ions is determined by the pseudo-first order kinetic equation. On the other hand, equilibrium data was best described by Langmuir adsorption isotherms. Density functional theory calculations (DFT) based on quantitative analyses were used to explore the interfacial interaction mechanisms, offering valuable perspectives on the inter- and intra-molecular interactions. Further studies on weak interaction were conducted, focusing on the binding contribution of electrostatic interaction and vdW potential. DFT results confirmed the strong adsorption capacity and coordination behavior of F - ions on the cross-linked Cs-Ech, suggesting that the Ech group offers preferred adsorption sites.

Transforming the Stability, Encapsulation, and Sustained Release Properties of Calcium Alginate Beads through Gel-Confined Coacervation.

Calcium alginate (Ca2+/alginate) gel beads find use in diverse applications, ranging from drug delivery and tissue engineering to bioprocessing, food formulation, and agriculture. Unless modified, however, these gels have limited stability in alkaline media (including phosphate buffers), and their high solute permeability limits their ability to efficiently encapsulate and slowly release water-soluble small molecules. Here, we show how these limitations can be addressed by mixing the alginate solutions used in the bead preparation with the nontoxic anionic polymer polyphosphate (PP). Upon complexing Ca2+ ions, PP undergoes complex coacervation (i.e., liquid/liquid phase separation into a Ca2+/PP-rich coacervate phase and a dilute supernatant phase). At lower PP concentrations, the Ca2+/PP coacervate appears to simply remain dispersed within the beads. Though its presence makes the beads more stable in alkaline media (phosphate-buffered saline and seawater), it has little impact on the bead stiffness, morphology, and (at least in the absence of substantial payload/coacervate association) encapsulation and release properties. When the PP concentrations exceed a critical value, however, Ca2+/PP coacervation within the gelling Ca2+/alginate beads collapses the resulting beads into more compact, interpenetrating polymer networks. Besides their enhanced stability to alkaline environments, these hybrid beads exhibit irregular morphologies with wrinkled and dimpled surface structures and macroscopic (closed) internal pores, and their collapse into these polymer-rich networks also makes them significantly stiffer than their PP-free counterparts. Crucially, these beads also exhibit a much lower solute permeability, which enables highly efficient encapsulation and multiday release of water-soluble small molecules (with the beads encapsulating >90% of the added model payload and sustaining its release over 3-5 d). Collectively, these findings provide a mild and simple (single-step) pathway to generating ionically cross-linked alginate beads with significantly enhanced stability, encapsulation efficiency, and sustained release.

Peptide Boronic Acids by Late-Stage Hydroboration on the Solid Phase.

Organoboron compounds have a wide range of applications in numerous research fields, and methods to incorporate them in biomolecules are much sought after. Here, on-resin chemical syntheses of aliphatic and vinylogous peptide boronic acids are presented by transition metal-catalyzed late-stage hydroboration of alkene and alkyne groups in peptides and peptoids, for example on allyl- and propargylglycine residues, using readily available chemicals. These methods yield peptide boronic acids with much shorter linkers than previously reported on-resin methods. Furthermore, the methods are regio- and stereoselective, compatible with all canonical amino acid residues and can be applied to short, long, and in part even "difficult" peptide sequences. In a feasibility study, the protected peptide vinylboronic acids are further derivatized by the Petasis reaction using salicylaldehyde derivatives. The ability of the obtained peptide boronic acids to reversibly bind to carbohydrates is demonstrated in a catch-release model experiment using a fluorescently labeled peptide boronic acid on cross-linked dextran beads. In summary, this highlights the potential of the target compounds for drug discovery, glycan-specific target recognition, controlled release, and diagnostics.

Fixed-bed adsorption of pesticide agricultural waste using cross-linked adsorptive hydrogel composite beads.

Adsorption column blockage due to solid adsorbent material is prevalent in laboratory-scale applications. Creating composite materials with stable geometries offers a viable solution. By crafting hydrogel beads using sodium alginate (Alg) and a bio-source like activated carbon (RMCA-P), it becomes possible to effectively eliminate agricultural pollutants, including the pesticide 2,4-D, from aqueous solutions. To evaluate the performance of these beads, a range of structural and textural analyses such as DRX, FTIR, SEM/EDX, BET, Zeta potential, Boehm titration, and iodine number were employed. Moreover, the study found that optimizing certain parameters greatly enhanced adsorption column efficiency. Specifically, increasing the bed height while reducing the flow rate of the adsorbate and the initial concentration in the inlet proved beneficial. The column demonstrated peak performance at a flow rate of 0.5 mL/min, a bed height of 35 cm, and an inlet adsorbate concentration of 50 mg/L. Under these conditions, the highest recorded removal rate for 2,4-D was 95.49%, which was subsequently confirmed experimentally at 95.05%. Both the Thomas and Yoon-Nelson models exhibited a good fit with the breakthrough curves. After undergoing three cycles of reuse, the RMCA-P/Alg hydrogel composite maintained a 2,4-D removal percentage of 74.21%. Notably, the RMCA-P/Alg beads exhibited effective removal of 2,4-D from herbicidal field waters in a continuous operational mode.

Adsorption of Heavy Metal Ions on Alginate-Based Magnetic Nanocomposite Adsorbent Beads.

Graphene oxide and its magnetic nanoparticle-based composites are a well-known tool to remove heavy metals from wastewater. Unfortunately, one of the major issues in handling such small particles consists of their difficult removal from treated wastewater (even when their magnetic properties are exploited), due to their very small diameter. One possible way to overcome this problem is to embed them in a macroscopic biopolymer matrix, such as alginate or chitosan beads. In this way, the adsorbent becomes easier to handle and can be used to build, for example, a packed column, as in a traditional industrial adsorber. In this work, the removal performances of two different embedded magnetic nanocomposite adsorbents (MNAs) are discussed. The first type of MNA is based on ferrite magnetic nanoparticles (MNPs) generated by coprecipitation using iron(II/III) salts and ammonium hydroxide, while the second is based on a 2D material composed of MNP-decorated graphene oxide. Both MNAs were embedded in cross-linked alginate beads and used to treat artificial water contaminated with chromium(III), nickel(II), and copper(II) in different concentrations. The yield of removal and differences between MNAs and non-embedded magnetic nanomaterials are also discussed. From the results, it was found that the time to reach the adsorption equilibrium is higher when compared to that of the nanomaterials only, due to the lower surface/volume ratio of the beads, but the adsorption capacity is higher, due to the additional interaction with alginate.

Effect of incorporating modified pinhão starch in alginate-based hydrogel beads for encapsulation of bioactive compounds by hydrodynamic electrospray ionization jetting

Known for its antioxidant properties, Araucaria angustifolia bracts extract was encapsulated using hydrodynamic electrospray ionization jetting within calcium alginate cross-linked hydrogel beads with varying contents of modified pinhão starch. The rheological properties of the dispersions and analysis of the physicochemical and digestive properties of encapsulated beads were studied. The results demonstrated that dispersions containing starch exhibited higher viscosity and reduced compliance values, indicating samples with stronger, more compact, and stable structures that are less susceptible to deformation. This was confirmed by the beads rupture strength test. The ATR-FTIR analysis suggest that no new chemical bonds were formed, with encapsulation being responsible only for physical interactions between the functional groups of the polymers used and the active groups of the compounds present in the extract. The thermal stability of starch-containing beads was higher. Total tannins were higher in beads containing starch, with 53.61 %, 56.83 %, and 66.99 % encapsulation yield for samples with 2 %, 4 %, and 6 % starch, respectively, and the remaining antioxidant activity ranged from 96.04 % to 81.08 %. In vitro gastrointestinal digestion simulation indicated that the highest releases occurred in the intestinal phase, ranging from 60.72 % to 63.50 % for the release of total phenolic compounds.

Chitosan coated biomass waste-based magnetic hydrogel beads for the removal of methylene blue

Due to developing technology and increasing population, human needs have increased, and textile activities have gained momentum. Many synthetic dyestuffs are used to meet the needs in this field. In this study, a cheap, useful, innovative, environmentally friendly and sustainable adsorbent was developed for the removal of Methylene Blue(MB), which is one of the dyes that is harmful to the environment. In the cultivation of fruit trees, in addition to the product, very high amounts of by-products/waste (garbage, branches, bark, leaves, etc.) are produced. In this direction, fig tree wastes were immobilized with chitosan, made magnetic, and MB adsorption on the developed adsorbent was examined in a batch system. Glutaraldehyde was used as crosslinker. Characterization of synthesized glutaraldehyde cross-linked chitosan-coated magnetic vegetable waste composite beads (g-CMBW) was carried out by SEM, EDX, FTIR and XRD. In the study, the effects of temperature (25–55 °C), pH (3.0–8.0), initial MB concentration (10–250mg/L), contact time (5–360min) and the amount of adsorbent (2–10 g/L) on MB adsorption with g-CMBW were examined. The optimum conditions obtained were determined as pH 6.0, temperature 25 °C, adsorbent amount 6 g/L, and contact time 120 min. The maximum adsorption capacity in MB removal using g-CMBW composite beads was calculated as 103.1 mg/g according to the Langmuir isotherm model. The temperature studies showed that the adsorption capacity decreased with increasing temperature, showing that the system was exothermic. In light of these results, it was determined that there are new promising adsorbents of natural origin, with higher adsorption capacity, lower cost, and alternatives to commercially used adsorbents in the removal of MB from aqueous media.

Development of magnetic La doped Al2O3 core-shell nanoparticle loaded hydrogel for selective recovery of fluoride from aquatic medium

The selective removal of pollutants from water bodies is regarded as a conciliation between the rapid expansion of industrial activities and need of clean water for sustainability. Fluoride is one such geogenic pollutant, and various materials have already been reported. Developing an efficient field employable material is however a challenge. Herein, we report the synthesis and competencies of strategically designed magnetic La-doped Al2O3 core-shell nanoparticle loaded polymeric nanohybrid as a benchmark fluoride sorbent. A facile synthesis strategy involved fabrication of Fe3O4 magnetic core followed by growth of La doped Al2O3 shell using sol-gel method. Doping of La2O3 into Al2O3 structure was optimised (6%), resulting in Fe3O4-Al0.94 La0.06O1.5 core-shell particles which provided exceptional fluoride affinity. The obtained magnetic Fe3O4-Al0.94La0.06O1.5 core-shell nanoparticles were then loaded (22%) into alginate to form cross-linked hydrogel beads (Fe3O4-Al0.94 La0.06 O1.5-Ca-ALG). These prepared hydrogel beads were characterised and utilized for selective recovery of fluoride under different ambient conditions. Driving forces for enhanced fluoride uptake by La doped Al2O3 were investigated and explained with the help of both experimental observation and theoretical simulation. Density functional theory calculations indicated significant expansion in the cell volume of Al2O3 due to La doping which favoured the fluoride sorption. The calculated defect formation energy for the incorporation of F into Al2O3 was found to decrease in the presence of La. XPS analysis suggested direct interaction of fluoride with Al, forming Al-F bond and breaking Al-O bond. Different vital parameters for uptake were optimised. Also, kinetics, isotherm and diffusion models were evaluated. Developed hydrogel beads attained record sorption capacity of 132.3mgg-1 for fluoride. Overall, excellent stability, no leaching of constituents, effectiveness for selective fluoride recovery from groundwater, brand it a perfect epitome of sustainable water treatment application.

Fe(III) cross-linked cellulose-agar hydrogel beads for efficient phosphate removal from aqueous solutions.

Fe(III) cross-linked cellulose agar beads (Fe-CLCAB) were synthesized by sol-gel method and employed as adsorbents for the removal of phosphate ions from aqueous medium. The synthesized Fe-CLCAB was characterized by its swelling property, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and UV-Vis absorption spectroscopic analysis. Batch adsorption studies were carried out to find out the optimum conditions of phosphate uptake. The adsorption process was found to fit both Langmuir and Freundlich adsorption isotherm model, pseudo-second-order kinetic model, and Elovich kinetic model. Ninety-four percent phosphate adsorption was achieved with 500 beads at pH 5. Maximum monolayer adsorption capacity was 73.13mg/g. A two-step elution process using sodium chloride solution was suitable for complete desorption of phosphate from Fe-CLCAB. Six cyclic adsorption-desorption tests were conducted using a 0.1M NaCl solution as desorbing agent. The removal efficiency of regenerated Fe-CLCAB was 42% of its original value after six cycles, which validates good stability and effectiveness of the prepared hydrogel beads. Ion exchange plays a vital role during adsorption/desorption of phosphate.

Cross-linked cellulose beads as an eco-friendly support for ZnO/SnO2/carbon xerogel hybrid photocatalyst: Exploring the synergy between adsorption and photocatalysis under simulated sunlight

This paper explores the application of cross-linked cellulose beads as a sustainable and cost-effective support for the ZnO/SnO2/carbon xerogel hybrid photocatalyst. The application of the developed photocatalytic beads, named CB-Cat, was directed at a simultaneous adsorption/photocatalysis process, which was carried out under simulated sunlight. The characterization of the CB-Cat indicated a good dispersion of the photocatalyst of choice throughout the cellulose matrix, confirming its incorporation into the cellulose beads. Furthermore, it is possible to observe the presence of the photocatalyst on the surface of the CB-Cat, confirming its availability for the photonic activation process. The results showed that the simultaneous adsorption/photocatalysis process was optimal for enhancing the efficiency of methylene blue (MB) removal, especially when compared to the isolated adsorption process. Additionally, the regeneration of the CB-Cat between cycles was favorable toward the maintenance of the MB removal efficiency, as the process carried out without regeneration displayed significant efficiency drops between cycles. Finally, the mechanism evaluation evidenced that hydroxyl and superoxide radicals were the main responsible for the MB photocatalytic degradation during illumination with simulated sunlight.

Effective removal of Allura red food dye from water using cross-linked chitosan-diatomite composite beads

Chitosan (Ch)-diatomite (D) composite beads (Ch-D) were synthesized using epichlorohydrin and tripolyphosphate crosslinkers and then moulded into uniform beads in tripolyphosphate solution. FT-IR and SEM-EDX analyses showed that Ch-D composite adsorbent was successfully synthesized by functionalization of chitosan to Ch-D by hydrogen bonding and electrostatic interactions and improved adsorption capacity for removal of Allura red AC (AR) food dye. The removal rate of AR food dye was found to be 98 % at 25 °C, natural AR dye pH value, 24 h, and at the initial AR dye concentration of 200 mg L−1. The maximum adsorption capacity was found to be 34.7 mg g−1. It was observed that π-π interactions, hydrogen bonds, and electrostatic interactions between the functional groups containing oxygen and amine on the surface of the Ch-D composite and the functional groups of the anionic AR dye, and AR dye adsorption via complexation took place. In light of all this information, the Ch-D composite adsorbent is a promising potential material for the effective treatment of colored pollutants from wastewater.

Alginate/geopolymer hybrid beads as an innovative adsorbent applied to the removal of 5-fluorouracil from contaminated environmental water

Water contaminated by cytostatic drugs has many negative impacts on the ecosystems. In this work, cross-linked adsorbent beads based on alginate and a geopolymer (prepared from an illito-kaolinitic clay) were developed for a promising decontamination of the 5-fluorouracil (5-FU) cytostatic drug from water samples. The characterization of the prepared geopolymer and its hybrid derivative was performed by scanning electron microscopy, X-ray diffraction, Fourier transform infrared and termogravimetric analysis.Batch adsorption experiments indicated that alginate/geopolymer hybrid beads (AGHB) allow an excellent 5-FU removal efficiency of up to 80% for a dosage adsorbent/water of 0.002 g/mL and a concentration of 5-FU of 2.5 mg/L. The adsorption isotherms data follow well the Langmuir model. The kinetics data favor the pseudo-second-order model. The maximum adsorption capacity (qmax) was 6.2 mg/g. The optimal adsorption pH was 4. Besides pore filling sorption process, the carboxyl and hydroxyl groups from alginate immobilized onto the geopolymer matrix favored the retention of 5-FU ions by hydrogen bonds. Common competitors, such as dissolved organic matter, do not significantly affected the adsorption. In addition, this material has not only eco-friendly and cost-effective advantages but also excellent efficiency when applied to real environmental samples such as wastewater and surface water. This fact suggests that it could have a great application in the purification of contaminated water.

Enhanced adsorptive removal of hazardous methyl violet 2B and methyl orange dyes by Algerian diatomite-loaded polysaccharide-based hydrogel beads

The present paper is devoted to the synthesis of hybrid biocomposites through immobilization of Algerian treated diatomite (TD) within the semi-interpenetrating network of carboxymethyl cellulose/dextran sulfate (CMC/DS). The physicochemical properties of the cross-linked beads were investigated by SEM, XRD, FTIR and TGA. Biocomposite beads were explored as adsorbents for the removal of cationic methyl violet 2B-(MV2B) and anionic methyl orange-(MO) dyes. The swelling ability in different media were studied. The outcomes revealed that the TD was successfully immobilized in CMC/DS matrix through hydrogen bonding which improved the structural stability of biocomposites. TD depicted to improve the adsorption capacity of hydrogels. Indeed, the beads prepared at low TD levels (5 and 10 % (w/w)) showed higher adsorption capacities (925.92 and 892.86 mgg−1) compared to the matrix (877.19 mg g−1). MV2B adsorption modeling showed the process well fitted the pseudo-second order kinetics and Langmuir models. Furthermore, the role of TD was better considered during the MO adsorption study. Pristine hydrogel were not able to effectively remove it (10 %), while for biocomposites the efficiency reached 62–98 %. The suggested mechanism for MO adsorption involved ion exchange, pore-filling and π-electron specific interactions. Lastly, reusability study confirm that C/D-TD biocomposites are promising materials for anionic/cationic dyes adsorption.

Removal of fluoride ions from water by cerium-carboxymethyl cellulose beads doped with CeO2 nanoparticles

A novel adsorbent for fluoride ions (F−) removal was prepared from cerium ion cross-linked carboxymethyl cellulose (CMC) biopolymer beads loaded with CeO2 nanoparticles (NPs). The characterization of the beads was performed by swelling experiments, scanning electron microscopy and Fourier transforms infrared spectroscopy. The adsorption of fluoride ions from aqueous solutions was carried out with both cerium ion cross-linked CMC beads (CMCCe) and CeO2-NPs added beads (CeO2-CMC-Ce) in a batch system. Optimized adsorption conditions were obtained by testing the parameters such as pH, contact time, adsorbent dose, and shaking rate at 25 °C. The adsorption process is well described by the Langmuir isotherm and pseudo-second-order kinetics. The maximum adsorption capacity was found as 105 and 312 mg/g F− for CMC-Ce and CeO2-CMC-Ce beads, respectively. Reusability studies showed that, the adsorbent beads have exhibited excellent sustainable properties up to 9 cycle usage. This study suggests that, CMC-Ce composite with CeO2 nanoparticles is a very effective adsorbent in removing fluoride from water.