Synthesis of new ammonium chitosan derivatives and their application for dye removal from aqueous media

Functionalization of carbon from rubber fruit shells (Hevea brasiliensis) with silane agents and its application to the adsorption of bi-component mixtures of methylene blue and crystal violet

In this research, activated carbon was obtained from rubber fruit shells (ACRPs). The obtained activated carbon (ACRPs) was modified by magnetite particle coating and silanization with triethoxyiphenylsilane (TEPS) to produce a new magnetic adsorbent (ACRPs-MS). The affinity of as-prepared adsorbent (ACRPs-MS) toward methylene blue (MB) and crystal violet (CV) dyes was tested in mono-component and bi-component solutions. Structural characterization proves the success of the magnetite coating process and the silanization of ACRPs. In the infrared (IR) spectroscopy spectrum of ACRPs-MS, Si-O-Fe and Si-O-Si bonds were identified, which indicated the presence of magnetite and silane. This is also supported by the elemental composition contained in the energy-dispersive X-ray (EDX) diffractogram. In addition, the presence of the porous structure of the surface of the material and the increase in the specific surface area increase the accessibility of contaminants such as MB and CV dyes to be adsorbed to the ACRPs-MS adsorption site effectively. The experimental results showed that the adsorption of mono-component MB and CV dyes by ACRPs-MS was optimum at pH 8 and an interaction time of 60 min. The adsorption kinetics of mono-component MB and CV dyes by ACRPs-MS tended to follow pseudo-second-order kinetics (PSO) models with PSO rate constant (k2) values of 0.198 and 0.993 g mg-1 min-1, respectively. The adsorption of MB and CV dyes by ACRPs-MS in a bi-component mixture tends to follow the Langmuir isotherm model with adsorption capacity (qm) values of 85.060 and 90.504 mg g-1, respectively. Analysis of adsorption data on the bi-component mixture between MB and CV by ACRPs-MS with the Langmuir isotherm equation for a binary mixture resulted in qm of 22.645 × 10-3 mmol equiv g-1. ACRPs-MS material can be used repeatedly five times with adsorption ability > 80%. Desorption of MB and CV dyes was carried out using 0.05 M HCl solution. ACRPs-MS material was able to adsorb MB and CV dyes with a large adsorption capacity and could be used in repeated adsorption. Thus, it can be stated that ACRPs-MS can be used as an effective adsorbent for MB and CV dyes, either singly or in a bi-component mixture.

Physicochemical fabrication of chitosan and algae with crosslinking glyoxal for cationic dye removal: Insight into optimization, kinetics, isotherms, and adsorption mechanism

Herein, a highly efficient and sustainable adsorbent of cross-linked chitosan-glyoxal/algae biocomposite (CHT-GLX/ALG) adsorbent was developed through an innovative hydrothermal cross-linking method. The CHT-GLX/ALG biocomposite was characterized using several complementary analytical methods that include CHN-O, XRD, FTIR, SEM-EDX, and pHpzc. This new adsorbent, named CHT-GLX/ALG, was utilized for the adsorption of a cationic dye (methyl violet 2B; MV 2B), from synthetic wastewater. The optimization of the dye adsorption process involved key parameters is listed: CHT-GLX/ALG dosage (from 0.02 to 0.1 g/100 mL), pH (from 4 to 10), and contact time (from 20 to 180 min) that was conducted using the Box-Behnken design (BBD). The optimal adsorption conditions for the highest decolorization efficiency of MV 2B (97.02 %) were estimated using the statistical model of the Box-Behnken design. These conditions include a fixed adsorbent dosage of 0.099 g/100 mL, pH 9.9, and a 179.9 min contact time. The empirical data of MV 2B adsorption by CHT-GLX/ALG exhibited favorable agreement with the Freundlich isotherm model. The kinetic adsorption profile of MV 2B by CHT-GLX/ALG revealed a good fit with the pseudo-second-order model. The maximum adsorption capacity (qmax) for MV 2B by CHT-GLX/ALG was estimated at 110.8 mg/g. The adsorption of MV 2B onto the adsorbent can be attributed to several factors, including electrostatic interactions between the negatively charged surface of CHT-GLX/ALG and the MV 2B cation, as well as n-π and H-bonding. These interactions play a crucial role in facilitating the effective adsorption of MV 2B onto the biocomposite adsorbent. Generally, this study highlights the potential of CHT-GLX/ALG as an efficient and sustainable adsorbent for the effective removal of organic dyes.

Kinetics, Equilibrium, and Thermodynamics for Conjugation of Chitosan with Insulin-Mimetic [meso-Tetrakis(4-sulfonatophenyl)porphyrinato]oxovanadate(IV)(4-) in an Aqueous Solution

This study investigated the conjugation of chitosan with the insulin-mimetic [meso-tetrakis(4-sulfonatophenyl)porphyrinato]oxovanadate(IV)(4-), VO(tpps), in an aqueous medium as a function of conjugation time, VO(tpps) concentrations, and temperatures. To validate the synthesis of chitosan-VO(tpps) conjugate, UV-visible and Fourier transform infrared spectrophotometric techniques were utilized. Conjugate formation is ascribed to the electrostatic interaction between the NH3+ units of chitosan and the SO3- units of VO(tpps). Chitosan enhances the stability of VO(tpps) in an aqueous medium (pH 2.5). VO(tpps) conjugation with chitosan was best explained by pseudo-second-order kinetic and Langmuir isotherm models based on kinetic and isotherm studies. The Langmuir equation determined that the maximal ability of VO(tpps) conjugated with each gram of chitosan was 39.22 μmol at a solution temperature of 45 °C. Activation energy and thermodynamic studies (Ea: 8.78 kJ/mol, ΔG: -24.52 to -27.55 kJ/mol, ΔS: 204.22 J/(mol K), and ΔH: 37.30 kJ/mol) reveal that conjugation is endothermic and physical in nature. The discharge of VO(tpps) from conjugate was analyzed in freshly prepared 0.1 mol/L phosphate buffer (pH 7.4) at 37 °C. The release of VO(tpps) from the conjugate is a two-phase process best explained by the Higuchi model, according to a kinetic analysis of the release data. Taking into consideration all experimental findings, it is proposed that chitosan can be used to formulate both solid and liquid insulin-mimetic chitosan-VO(tpps) conjugates.

Removal of dyes from water using Citrullus lanatus seed powder in continuous and discontinuous systems

The objective of this study is to develop a low-cost biosorbent using residual seeds of the Citrullus lanatus fruit for the removal of cationic dyes. Physicochemical parameters such as pH, adsorbent mass, contact time, and temperature were evaluated for their effects on dye removal. The biosorbent is composed of lignin and cellulose, exhibiting a highly heterogeneous surface with randomly distributed cavities and bulges. The adsorption of both dyes was most effective at natural pH with a dosage of 0.8 g L-1. Equilibrium was reached within 120 min, regardless of concentration, indicating rapid kinetics. The Elovich model and pseudo-second-order kinetics were observed for crystal violet and basic fuchsin dye, respectively. The Langmuir model fitted well with the equilibrium data of both dyes. However, the increased temperature had a negative impact on dye adsorption. The biosorbent also demonstrated satisfactory performance (R = 43%) against a synthetic mixture of dyes and inorganic salts, with a small mass transfer zone. The adsorption capacities for crystal violet and basic fuchsin dye were 48.13 mg g-1 and 44.26 mg g-1, respectively. Thermodynamic studies confirmed an exothermic nature of adsorption. Overall, this low-cost biosorbent showed potential for the removal of dyes from aqueous solutions.

Magnetite carboxymethylcellulose as biological macromolecule-based absorbent for cationic dyes removal from environmental samples

In this study, magnetite carboxymethylcellulose (CMC@Fe₃O₄) composite as magnetic biological molecules were synthetized for the use as adsorbent to remove four types of cationic dyes, namely Methylene Blue, Rhodamine B, Malachite Green, and Methyl Violet from aqueous solution. The characteristic of the adsorbent was achieved by Fourier Transform Infrared Spectroscopy, Field Emission Scanning Electron Microscope (FESEM), X-ray Diffraction, Vibrating Sample Magnetometer and Thermal Gravimetric Analysis techniques. Besides, essential influencing parameters of dye adsorption; the solution pH, solution temperature, contact time, adsorbent concentration and initial dye dosage were studied. FESEM analysis showed the magnetic Fe₃O₄-TB, Fe₃O₄@SiO₂, Fe₃O₄@SiO₂-NH₂ and CMC@Fe₃O₄ composites were in spherical shape, with average size of 43.0 nm, 92.5 nm, 134.0 nm and 207.5 nm, respectively. On the saturation magnetization (Ms), the results obtained were 55.931 emu/g, 34.557 emu/g, 33.236 emu/g and 11.884 emu/g. From the sorption modelling of Isotherms, Kinetics, and Thermodynamics, the adsorption capacity of dyes is (MB = 103.33 mg/g), (RB = 109.60 mg/g), (MG = 100.08 mg/g) and (MV = 107.78 mg/g). With all the adsorption processes exhibited as exothermic reactions. The regeneration and reusability of the synthetized biological molecules-based adsorbent was also assessed.

Magnetic Ionotropic Hydrogels Based on Carboxymethyl Cellulose for Aqueous Pollution Mitigation

In this work, stabilized ionotropic hydrogels were designed using sodium carboxymethyl cellulose (CMC) and assessed as inexpensive sorbents for hazardous chemicals (e.g., Methylene Blue, MB) from contaminated wastewaters. In order to increase the adsorption capacity of the hydrogelated matrix and facilitate its magnetic separation from aqueous solutions, sodium dodecyl sulfate (SDS) and manganese ferrite (MnFe₂O₄) were introduced into the polymer framework. The morphological, structural, elemental, and magnetic properties of the adsorbents (in the form of beads) were assessed using scanning electron microscopy (SEM), energy-dispersive X-ray analysis, Fourier-transform infrared spectroscopy (FTIR), and a vibrating-sample magnetometer (VSM). The magnetic beads with the best adsorption performance were subjected to kinetic and isotherm studies. The PFO model best describes the adsorption kinetics. A homogeneous monolayer adsorption system was predicted by the Langmuir isotherm model, registering a maximum adsorption capacity of 234 mg/g at 300 K. The calculated thermodynamic parameter values indicated that the investigated adsorption processes were both spontaneous (ΔG < 0) and exothermic (ΔH < 0). The used sorbent can be recovered after immersion in acetone (93% desorption efficiency) and re-used for MB adsorption. In addition, the molecular docking simulations disclosed aspects of the mechanism of intermolecular interaction between CMC and MB by detailing the contributions of the van der Waals (physical) and Coulomb (electrostatic) forces.

GO-CuO nanocomposites assimilated into CA-PES polymer membrane in adsorptive removal of organic dyes from wastewater

Textile industries are one of the leading environmental pollutants by releasing harmful dye effluents. In many textile distrts, the amount of excess color in treated textile effluent that exceeds regulatory limitations is still being a major concern. The combining usage of nanomaterials and polymer material to solve these issues using various techniques. In this research, graphene oxide-copper oxide (GO-CuO) nanomaterial have been incorporated into cellulose-acetate (CA), poly-ether sulfone (PES) blend polymer by using phase inversion process to fabricate thin film nanocomposite (TFN) membrane for removal of dye pollutant. The physiochemical properties of prepared TFN materials were studied by Fourier transform infra-red spectroscopy (FT-IR), X-ray diffractometer (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), thermo gravimetric analysis (TGA), and mechanical strength analysis. Dye adsorption experiments were performed with four typical water-soluble organic dyes methylene blue (MB), rhodamine blue (Rh. B), methyl orange (MO) and Congo red (CR). After reaching adsorption equilibrium, the composite membrane final removal effectiveness for MB 92.42%, Rh. B 89.39%, CR 68.39%, and MO 58.82% respectively. As a result, the fabricated TFN material proves to be an effective adsorbent material for cationic dye molecules. Also, when the fabricated material was tested with textile industry effluent sample, all physio-chemical properties exhibited a considerable decrease in concentrations when compared to the real textile effluent concentration. The treated effluents permitted for a relatively greater growth and germination index of Tropical amaranth roots than the textile effluent, this demonstrates that phytotoxicity testing was also successful. The most effective temperature, concentration and pH were found to be 273 K, 1 × 10^-5 M and pH 9. The fabricated TFN membrane material (GO-CuO @ CA-PES) can be recommended for water treatment applications.

An Intelligent Carbon-Based Prediction of Wastewater Treatment Plants Using Machine Learning Algorithms

Purification of polluted water and return back to the agriculture field is the wastewater treatment for plants. Contaminated water causes illness and health emergencies of public. Also, health risk due release of toxic contaminants brings problem to all living beings. At present, sensors are used in waste water treatment and transfer data via internet of things (IoT). Prediction of wastewater quality content which is presence of total nitrogen (T-N) and total phosphorous (T-P) elements, chemical oxygen demand (COD), biochemical demand (BOD), and total suspended solids (TSS) is associated with eutrophication that should be prevented. This may leads to algal bloom and spoils aquatic life which is consumed by human. The presence of nitrogen and phosphorous elements is in the content of wastewater, and these elements are associated with eutrophication which should be prevented. Adsorption of T-N and T-P activated carbon was predictable as one of the most promising methods for wastewater treatment. Many research works have been done. The issues are inefficiency in the prediction of wastewater treatment. To overcome this issue, this paper proposed fusion of B-KNN with the ELM algorithm that is used. The accuracy of the BKNN-ELM algorithm in classification of water quality status produced the highest accuracy of the highest accuracy which is $K=9$ and $k=10$ with rate of accuracy which is 93.56%, and the lowest accuracy is $K=1\text{of}65.34\%$ . Experiment evaluation shows that a total suspended solid predicted by proposed model is 91 with accuracy of 93%. The relative error rate of prediction is 12.03 which is lesser than existing models.

A decade development in the application of chitosan-based materials for dye adsorption: A short review

The presence of dyes in the aquatic environment as a result of anthropogenic activities, especially textile industries, is a critical environmental challenge that hinders the availability of potable water. Different wastewater treatment approaches have been used to remediate dyes in aquatic environments; however, most of these approaches are limited by factors ranging from high cost to the incomplete removal of the dyes and contaminants. Thus, the use of adsorption as a water treatment technology to remove dyes and other contaminants has been widely investigated using different adsorbents. This study evaluated the significance of chitosan as a viable adsorbent for removing dyes from water treatment. We summarised the literature and research results obtained between 2009 and 2020 regarding the adsorption of dyes onto chitosan and modified chitosan-based adsorbents prepared through physical and chemical processing, including crosslinking impregnation, grafting, and membrane preparation. Furthermore, we demonstrated the effects of various chitosan-based materials and modifications; they all improve the properties of chitosan by promoting the adsorption of dyes. Hence, the application of chitosan-based materials with various modifications should be considered a cutting-edge approach for the remediation of dyes and other contaminants in aquatic environments toward the global aim of making potable water globally available.

Recycling electro-coagulated sludge from textile wastewater treatment plants as an adsorbent for the adsorptions of fluoride in an aqueous solution

This research investigated the high content of iron-based materials from recycled electro-coagulated (EC) sludge for the adsorptive removal of fluoride, and the properties of the material were characterized. The thermal activation of EC sludge in which the unwanted impurity was removed by beneficiation and thermally activated at 500 °C, and was used for fluoride removal. Basic operating parameters (mixing time, adsorbent dosage, adsorbate concentration, solution pH, and temperature) were examined to evaluate the optimum de-fluoridation capacity (DC). The functional groups, the crystalline structure, and surface morphology of thermally treated and raw EC sludge were analyzed using FTIR, XRD, and SEM, respectively, and demonstrates that thermally activated EC sludge contains significant content of magnetite and hematite. The optimum DC was recorded as 5.12 mg of F⁻/gm with experimental conditions: mixing time = 20 min, adsorbent dosage = 0.3 gm/100 ml, initial fluoride concentration = 1 mg/L, and pH = 5 at the temperature of 353 K. The Langmuir isotherm model was fitted, and the capacity is calculated as 6.43 mg/g. The adsorption process follows the Pseudo-Second-order kinetic models. It can be concluded that the prepared adsorbents have excellent fluoride removal capacity, and EC sludge can be used as an alternative adsorbent for de-fluoridation.

•

Iron-based oxides and hydroxides from the EC sludge were recovered and prepared for fluoride ion adsorption.

•

EC sludge as an iron-based adsorbent was synthesized by thermal activation at 500 °C.

•

Iron oxide adsorbents could efficiently remove fluoride ions from synthetically prepared water solutions.

•

The adsorption of fluoride followed a Langmuir isotherm pseudo-Second-order kinetic model.

•

The prepared adsorbents were regenerated in an aqueous solution and the reusability efficiency was up to the 4th cycle.

Activated Carbon for Dyes Removal: Modeling and Understanding the Adsorption Process

Batch adsorption experiments have been conducted to investigate the removal of methyl orange from aqueous solution by an activated carbon prepared from prickly pear seed cake by phosphoric acid activation. The adsorption process has been described by using kinetic and isotherm models. The kinetic of adsorption was examined by pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. Adsorption isotherm was modeled using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms. The adsorption process of methyl orange was well explained by the pseudo-second-order model and Freundlich isotherm. Also, pseudo-n-order model has been applied to estimate the order of adsorption kinetic and it was found equal to 2 which confirm the good accuracy of the pseudo-second order. Moreover, Dubinin–Radushkevich isotherm reveals that the adsorption of methyl orange onto activated carbon was a physisorption process in nature. The adsorption capacity of activated carbon was found to be 336.12 mg/g at temperature 20°C andpH∼7. These results demonstrated that the prickly pear seed cake is a suitable precursor for the preparation of appropriate activated carbon for dyes removal from aqueous solution.

Adsorption Thermodynamic and Kinetic Studies of Methyl Orange onto Sugar Scum Powder as a Low-Cost Inorganic Adsorbent

In the present study, batch adsorption experiments were carried out to investigate the removal of methyl orange (MO) from aqueous solution using sugar scum powder as an effective inorganic adsorbent which is a cheap precursor and abundant. The characteristics of this material were determined using XRD, SEM/EDX, and FTIR. The adsorption performance of sugar scum powder was evaluated using MO as the model adsorbate. Effects of various parameters such as initial dye concentration, contact time, and adsorbent dose were studied. The adsorption process can be best described by the pseudo-second-order kinetic and Langmuir adsorption isotherm models. Maximum monolayer adsorption capacity for MO removal was found to be 15.24 mg/g at temperature 22°C and pH 7.2. Moreover, thermodynamic parameters suggested that the adsorption of MO onto sugar scum powder was a spontaneous and exothermic process. The results demonstrated that sugar scum is a suitable precursor for the preparation of efficient adsorbent for dye removal from wastewater.

Plasma-induced synthesis of chitosan-g-polyacrylamide and its flocculation performance for algae removal

Chitosan (CS)-g-polyacrylamide (PAM) is a highly efficient and environmentally friendly flocculant, which was synthesized through plasma-induced graft copolymerization of CS and acrylamide (AM). The effects of monomer concentration, AM:CS ratio, discharge power, discharge time, post-polymerization temperature, and post-polymerization time on the intrinsic viscosity, grafting ratio, and grafting efficiency of CS-g-PAM were investigated. The optimum conditions of graft copolymerization were as follows: 20% monomer concentration, 7:3 AM:CS ratio, 40 W discharge power, 90 s discharge time, 50°C post-polymerization temperature, and 24 h post-polymerization time. The structural characteristics of CS-g-PAM were characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction. CS-g-PAM exhibited better flocculation efficiency than the commercially available PAM in both diatomite-simulated wastewater and low-turbidity algal water. The optimal turbidity removal efficiency for the diatomite-simulated wastewater was 99.9%, which was obtained with 6 mg L^-1 of CS-g-PAM at pH 11.0 and 250 s^-1 of velocity gradient. In low-turbidity algal water, the optimal removal efficiencies for chlorophyll-a, turbidity, and COD were 93.6%, 94.5%, and 98.2%, respectively.

Aminonitrones as highly reactive bifunctional synthons. An expedient one-pot route to 5-amino-1,2,4-triazoles and 5-amino-1,2,4-oxadiazoles – potential antimicrobials targeting multi-drug resistant bacteria

A four-component one-pot reaction proceeds very rapidly under mild conditions and gives the heterocyclic systems in good yields.

3-Dialkylamino-1,2,4-triazoles via ZnII-Catalyzed Acyl Hydrazide-Dialkylcyanamide Coupling

Zinc(II)-catalyzed (10 mol % ZnCl₂) coupling of acyl hydrazides and dialkylcyanamides in ethanol leads to 3-dialkylamino-1,2,4-triazoles (76-99%; 17 examples). This reaction represents a novel, straightforward, and high-yielding approach to practically important 3-NR₂-1,2,4-triazoles, which utilizes commercially available and/or easily generated substrates. Seventeen new 3-NR₂-1,2,4-triazoles were characterized by HRESI⁺-MS and IR, ¹H, and ¹³C{¹H} NMR spectroscopies and five species additionally by single-crystal X-ray diffraction (XRD). The Zn^II-catalyzed reaction proceeds via initial generation of the [Zn{RC(=O)NHNH₂}₃](ZnCl₄) complexes (exemplified by isolation of the complex with R = Ph, 76%; characterized by HRESI⁺-MS, IR, CP-MAS TOSS ¹³C{¹H} NMR, and XRD). Electronic effects of substituents at the acyl hydrazide moiety do not significantly affect the reaction rate and the yield of the target triazoles, whereas the steric hindrances reduce the reaction rate without affecting the yield of the heterocycles.

Adsorption of toxic acidic dye from aqueous solution onto diethylenetriamine functionalized magnetic glycidyl methacrylate-N,N′-methylenebisacrylamide

Magnetic sorbent microgranules with magnetite (Fe₃O₄) core and glycidyl methacrylate/N,N′​-methylenebisacrylamide shell were prepared. The sorbent was tested for Acid Yellow 99 dye removal from aqueous solution.

Sorptive removal of Remazol Brilliant Blue R from aqueous solution by diethylenetriamine functionalized magnetic macro-reticular hybrid material

Chitosan, glycidyl methacrylate (synthetic polymer) and magnetite are combined to produce novel magnetic macro-reticular hybrid synthetic–natural materials which are shown to be effective sorbents for RBBR ions.

Flocculation of copper(II) and tetracycline from water using a novel pH- and temperature-responsive flocculants

Insufficient research is available on flocculation of combined pollutants of heavy metals and antibiotics, which widely exist in livestock wastewaters. Aiming at solving difficulties in flocculation of this sort of combined pollution, a novel pH- and temperature-responsive biomass-based flocculant, carboxymethyl chitosan-graft-poly(N-isoproyl acrylamide-co-diallyl dimethyl ammonium chloride) (denoted as CND) with two responsive switches [lower critical solution temperature (LCST) and isoelectric point (IEP)], was designed and synthesized. Its flocculation performance at different temperatures and pHs was evaluated using copper(II) and tetracycline (TC) as model contaminants. CND exhibited high efficiency for coremoval of both contaminants, whereas two commercial flocculants (polyaluminum chloride and polyacrylamide) did not. Especially, flocculation performance of the dual-responsive flocculant under conditions of temperature>LCST and IEP(contaminants)<pH<IEP(CND) was much better than that under other conditions. Further investigation on flocculation mechanism via pH monitoring, zeta potential measurements, floc properties analyses and spectral characterization indicated that, pairwise interactions among CND, copper(II) and TC were present in bridging flocculation, including charge attraction, coordination and hydrophobic effect. Based on these pairwise interactions, copper(II) and TC exerted "aid" roles to each other's removal with the existence of CND, and preferable flocculation performance was thus achieved.

Recent modifications of chitosan for adsorption applications: a critical and systematic review

Chitosan is considered to be one of the most promising and applicable materials in adsorption applications. The existence of amino and hydroxyl groups in its molecules contributes to many possible adsorption interactions between chitosan and pollutants (dyes, metals, ions, phenols, pharmaceuticals/drugs, pesticides, herbicides, etc.). These functional groups can help in establishing positions for modification. Based on the learning from previously published works in literature, researchers have achieved a modification of chitosan with a number of different functional groups. This work summarizes the published works of the last three years (2012-2014) regarding the modification reactions of chitosans (grafting, cross-linking, etc.) and their application to adsorption of different environmental pollutants (in liquid-phase).

Synthesis of cationic chitosan hydrogel with long chain alkyl and its controlled glucose-responsive drug delivery behavior

A novel glucose-sensitive system based on cationic chitosan hydrogel with a long chain alkyl (HDCC) was synthesized, which demonstrated distinct pH- and glucose-sensitivity with an improved slow-release effect.

Fast removal of uranium from aqueous solutions using tetraethylenepentamine modified magnetic chitosan resin

Chitosan was cross-linked using glutaraldehyde in the presence of magnetite. The resin was chemically modified through the reaction with tetraethylenepentamine (TEPA) to produce amine bearing chitosan. The resin showed a higher affinity towards the uptake of UO2(2+) ions from aqueous medium: maximum sorption capacity reached 1.8 mmol g(-1) at pH 4 and 25 °C. The nature of interaction of UO2(2+) ions with the resin was identified. Kinetics were carried out at different temperatures and thermodynamic parameters were evaluated. Breakthrough curves for the removal of UO2(2+) were studied at different flow rates, bed heights and after 3 regeneration cycles. Hydrochloric acid (0.5 M) was used for desorbing UO2(2+) from loaded resin: desorption yield as high as 98% was obtained.