Sorption behaviour of copper on chemically modified chitosan beads from aqueous solution

Chitosan-Silica Composite Aerogel for the Adsorption of Cupric Ions

A chitosan-silica hybrid aerogel was synthesized and presented as a potential adsorbent for the purification of cupric ion-contaminated media. The combination of the organic polymer (chitosan), which can be obtained from fishery wastes, with silica produced a mostly macroporous material with an average pore diameter of 33 µm. The obtained aerogel was extremely light (56 kg m-3), porous (96% porosity, 17 cm3 g-1 pore volume), and presented a Brunauer-Emmett-Teller surface area (SBET) of 2.05 m2 g-1. The effects of solution pH, aerogel and Cu(II) concentration, contact time, and counterion on cupric removal with the aerogel were studied. Results showed that the initial pH of the cation-containing aqueous solution had very little influence on the removal performance of this aerogel. According to Langmuir isotherm, this material can remove a maximum amount of ca. 40 mg of cupric ions per gram and the kinetic data showed that the surface reaction was the rate-limiting step and equilibrium was quickly reached (in less than one hour). Thus, the approach developed in this study enabled the recovery of waste for the preparation of a novel material, which can be efficiently reused in a new application, namely water remediation.

A review on heavy metal biosorption utilizing modified chitosan

Heavy metal pollution in water bodies is a global concern. The prominent source of metal contamination in aqueous streams and groundwater is wastewater containing heavy metal ions. Elevated concentrations of heavy metals in water bodies can have a negative impact on water quality and public health. The most effective way to remove metal contaminants from drinking water is thought to be adsorption. A deacetylated derivative of chitin, chitosan, has a wide range of commercial uses since it is biocompatible, nontoxic, and biodegradable. Due to its exceptional adsorption behavior toward numerous hazardous heavy metals from aqueous solutions, chitosan and its modifications have drawn a lot of interest in recent years. Due to its remarkable adsorption behavior toward a range of dangerous heavy metals, chitosan is a possible agent for eliminating metals from aqueous solutions. The review has focused on the ideas of biosorption, its kinds, architectures, and characteristics, as well as using modified (physically and chemically modified) chitosan, blends, and composites to remove heavy metals from water. The main objective of the review is to describe the most important aspects of chitosan-based adsorbents that might be beneficial for enhancing the adsorption capabilities of modified chitosan and promoting the usage of this material in the removal of heavy metal pollutants.

Preparation of a modified silk-based gel/microsphere composite as a potential hepatic arterial embolization agent

Transcatheter arterial chemoembolization (TACE) is an effective method for treating hepatocellular carcinoma (HCC). In this study, chitosan (CS), sodium glycerophosphate (GP), and sodium alginate (SA) were used as the main raw materials to develop clinically non-degradable embolization microspheres (Ms). Chitosan/sodium alginate embolization Ms. were generated using an emulsification cross-linking method. The Ms. were then uniformly dispersed in CS/GP temperature-sensitive gels to produce Gel/Ms. composite embolic agents. The results showed that Gel/Ms. had good morphology and a neatly arranged three-dimensional structure, and the Ms. dispersed in the Gel as evidenced by SEM. Furthermore, Gel/Ms. has good blood compatibility, with a hemolysis rate of ≤5 %. The cytotoxicity experiments have also proven its excellent cell compatibility. The degradation rate of Gel/Ms. was 58.869 ± 1.754 % within 4 weeks, indicating that Gel/Ms. had good degradation performance matching its drug release purpose. The Gel/Ms. adheres better at the target site than Ms. alone and releases the drug steadily over a long period, and the maximum release rate of Gel/Ms. within 8 h was 38.33 ± 1.528 %, and within 168 h was 81.266 ± 1.193 %. Overall, Gel/Ms. demonstrate better slow drug release, reduced sudden drug release, prolonged drug action time at the target site, and reduced toxic side effects on the body compared to Gel alone.

Outstanding Sorption of Copper (II) Ions on Porous Phenothiazine-Imine-Chitosan Materials

The aim of this work was to investigate the ability of a solid-state material, prepared by crosslinking chitosan with a phenothiazine-based aldehyde, to remove copper (II) ions from aqueous solutions, in a fast and selective manner. The metal uptake experiments, including the retention, sensibility, and selectivity against eight different metal ions, were realized via batch adsorption studies. The capacity of the material to retain copper (II) ions was investigated by spectrophotometric measurements, using poly(ethyleneimine) complexation agent, which allowed detection in a concentration range of 5-500 µM. The forces driving the copper sorption were monitored using various methods, such as FTIR spectroscopy, X-ray diffraction, SEM-EDAX technique, and optical polarized microscopy, and the adsorption kinetics were assessed by fitting the in vitro sorption data on different mathematical models. The phenothiazine-imine-chitosan material proved high ability to recover copper from aqueous media, reaching a maximum retention capacity of 4.394 g Cu (II)/g adsorbent when using a 0.5 M copper solution, which is an outstanding value compared to other chitosan-based materials reported in the literature to this date. It was concluded that the high ability of the studied xerogel to retain Cu (II) ions was the result of both physio- and chemo-sorption processes. This particular behavior was favored on one hand by the porous nature of the material and on the other hand by the presence of amine, hydroxyl, imine, and amide groups with the role of copper ligands.

Evaluation of diethylenetriaminepentaacetic acid modified chitosan immobilized in amino-carbmated alginate matrix as a low cost adsorbent for effective Cu(II) recovery

In present work, facile synthesis of a biocompatible hybrid biosorbent based on diethylenetriaminepentaacetic acid (DTPA) modified chitosan immobilized in organo-functionalized sodium alginate matrix (DTPA-MCSA) was carried out. DTPA-MCSA was casted in microspherical hydrogel beads. Three dimensional microporous geometry of the biosorbent remained well preserved as observed in SEM analysis which revealed the improved mechanical strength of the alginate matrix. Surface functionalization of base biopolymers was confirmed by FTIR and SEM analysis. Equilibrium sorption studies using DTPA-MCSA for Cu(II) from aqueous medium were carried out in batch mode and found considerably dependent on pH, contact sorption time, temperature and initial copper concentration. Isothermal sorption data showed close correlation with Langmuir model as evident from nonlinear fitting of data (R 2 ˜ 0.99) at different temperatures. The experimental sorption capacity (q e) was found nearly 67 mg/g using 100 mg/L initial concentration of copper ions. Kinetic studies were conducted using different initial concentrations for better elucidation of results and it showed better correlation with pseudo second order rate equation which unveiled that strong ion pair coordination and complexation exist between Cu(II) and newly grafted chelating sites of DTPA-MCSA. Thermodynamic parameters suggested that the adsorption process is spontaneous and endothermic. The results concluded that DTPA-MCSA could be a better candidate for adsorptive remediation of copper ions from liquid waste.

Synthesis of hybrid biosorbent based on 1,2-cyclohexylenedinitrilotetraacetic acid modified crosslinked chitosan and organo-functionalized calcium alginate for adsorptive removal of Cu(II)

The present study is based on the synthesis of a novel hybrid biosorbent using 1,2-cyclohexylenedinitrilotetraacetic acid modified crosslinked chitosan and amino-thiocarbamate moiety functionalized sodium alginate (CDTA-CS/TSC-CA). The fabricated sorbent was employed to investigate the efficient recovery of Cu(II) from aqueous media. CDTA-CS/TSC-CA was characterized using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Analysis confirmed the successful modification of both biopolymers and subsequent loading of Cu(II) ions. CDTA-CS/TSC-CA was casted in the form of hydrogel beads having different CDTA-CS to TSC-CA mass ratios i.e., 10.0-40.0% by mass. The hydrogel beads 4CDTA-CS/TSC-CA with CDTA-CS/TSC-CA mass ratio of 40.0% was found most effective for copper sorption. Equilibrium sorption results showed that initial concentration of copper, medium pH, contact time, sorbent dosage and temperature influenced the sorption capacity (q_e). Rate of sorption data was interpreted using different kinetic models and found best fitted with pseudo second order rate expression (R² ≈ 0.99), illustrating that the rate determining step includes the electron density transfer from sorbent coordination sites to central copper ions. Crank's RIDE equation and Elovich chemisorption model (ECM) revealed the presence of two sorption phases, initially rapid sorption followed by comparatively a slow uptake. Equilibrium sorption data was well depicted by Langmuir model and maximum monolayer adsorption capacity (q_m) was computed as 276.53 mg·g^-1 at 298 K. Standard Gibbs free energy change, ∆G° (-19.99, -20.18 and -20.36 kJ/ mol), standard enthalpy change, ∆H° (-8.95 kJmol) and standard entropy change, ∆S° (0.04 kJ/mol K^-1) values suggested that the adsorption process is spontaneous and exothermic. Hence, 4CDTA-CS/TSC-CA was found efficient biosorbent for copper removal from its dilute effluents.

Nanomodified sugarcane bagasse biosorbent: synthesis, characterization, and application for Cu(II) removal from aqueous medium

Biosorption is a technique widely used in the remediation of contaminated effluents, and its main advantages are its easy applicability, high efficiency rate, versatility, and its economic viability. Associated with nanotechnology, this work proposes the use of nanocomposites of sugarcane bagasse (SB) and ferromagnetic nanoparticles (Fe₃O₄) in the removal of metallic ions present in contaminated water. SB is a promising adsorbent material since it is an abundant agricultural residue, easily accessed. By using the coprecipitation method, two nanocomposites were obtained from in natura (SB-NP) or acid-treated (MSB-NP) sugarcane bagasse. These materials were synthetized by impregnation of Fe₃O₄ to gain paramagnetic properties and to facilitate the removal of the contaminant-containing adsorbent. The characterization of the nanocomposites was performed using pH_PCZ, FTIR, XRD, and SEM/EDS techniques, to evaluate the synthesis efficiency and investigate the morphology of the materials. The efficiency of magnetite impregnation on the SB was assessed by SEM/EDS and XRD, while the main functional groups (carbonyl, carboxyl, hydroxyl, amine, amide, and nitrate) responsible for adsorption were found by FTIR. In the surface charge characterization by pH_PCZ sorption of dyes, it was found that negative charges are predominant. The pH_PCZ for SB-NP and MSB-NP was 5.95 and 5.59, respectively, and the chosen Cu(II) adsorption pH was 6.2 ± 0.1. The adsorption equilibrium was reached between 10 and 60 min of contact time. The maximum experimental sorption capacity (SC_exp) was 2.53 ± 0.09 (SB-NP) and 2.61 ± 0.01 mg/g (MSB-NP). The isotherm models applied to the experimental data were Langmuir, Freundlich, Sips, Temkin, and Dubinin-Radushkevich, and Temkin best described the adsorption phenomena for Cu(II) by SB-NP (r² = 0.9976 and χ² = 3.965) and MSB-NP (r² = 0.9990 and χ² = 1.816). Reuse cycles of the nanocomposites were also performed employing ten cycles of sorption using 50 mg/L Cu(II) solutions, after which the materials showed SC_exp = 7.47 ± 0.04 mg/g (SB-NP) and 7.82 ± 0.04 mg/g (MSB-NP). Therefore, the investigated materials exhibited promising results to be used as biosorbents in the remediation of effluents contaminated with toxic metal ions, such as copper.

A systematic review on carbohydrate biopolymers for adsorptive remediation of copper ions from aqueous environments-Part B: Isotherms, thermokinetics and reusability

The presence of copper in aquatic environment is a serious threat for human health and ecosystem conservation. Adsorption is a powerful, operable and economic method for remediation of copper ions from aqueous phase. Carbohydrate biopolymers have emerged as promising, effective and environmental-friendly adsorbents for copper remediation. In part A of this review, different types of carbohydrate biopolymer adsorbents were surveyed focusing on prevalent and novel synthesis and modification methods. In current work (part B of the review), isothermal, thermodynamic and kinetic aspects of the copper adsorption by carbohydrate-based adsorbents as well as the regeneration and reusability of the biopolymer adsorbents are overviewed. Adsorption capacity, time required for equilibrium (adsorption rate), thermal-sensitivity of the adsorption, favorability extent, and sustainability of the adsorbents and adsorption processes are valuable and useful outcomes, resulted from the thermokinetic and reusability investigations. Such considerations are critical for the process design and scale up regarding technical, economical and sustainability of the adsorption process.

Development of chitosan encapsulated tricalcium phosphate biocomposite for fluoride retention

The powder form of tricalcium phosphate (TCP) causes the significant pressure drop which limit its application under field conditions. To trounce such technological troubles and to enhance the defluoridation capacity (DC) of TCP, chitosan (CS) encapsulated TCP polymeric composite was prepared by dispersing TCP particles into chitosan polymeric matrix to produce tricalcium phosphate/chitosan (TCPCS) composite which could be made into any desirable form. The synthesized TCPCS composite possesses an enhanced DC of 1034 mgF^-/kg than the individual components viz., TCP and chitosan which has got DC of 490 and 52 mgF^-/kg respectively. The prepared adsorbents were characterized by FTIR, SEM and EDAX analysis. The various physico-chemical properties such as contact time, solution pH, co-anions and temperature were optimized to get maximum defluoridation. The equilibrium and kinetic experiments were conducted for TCPCS composite toward fluoride removal. The practical applicability of TCPCS composite was examined at field conditions.

Synthesis of carboxyl-introduced chitosan with C2 amine groups protected and its use in copper (II) removal

A route for the formation of carboxyl-introduced chitosan (CI-CS) with C₂ amine groups protected (CIAP-CS) was investigated to improve copper (II) adsorption. First, the C₂ amine groups of the chitosan (CS) were protected via a Schiff-base reaction by benzaldehyde. Then the product was obtained by the introduction of pyromellitic dianhydride to the C₆ hydroxyl groups on CS via epichlorohydrin. The last product was obtained by removing the Schiff base with dilute hydrochloride solution. CI-CS without C₂ amine groups protected was directly synthesized as well. The adsorbents were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD) and X-ray photoelectron spectrometer (XPS). The adsorption properties for copper (II) were investigated. FTIR spectroscopy and XPS clearly showed that most of the amine groups in CS were converted to -N = CH₂ groups after the benzaldehyde treatment and that no cross-linking reactions with CS were involved; the HCl treatment after the cross-linking reaction effectively released nitrogen atoms protected into the form of the primary amine again. The results confirm that the CIAP-CS cross-linked with the new method had significantly greater adsorption capacities than the CI-CS cross-linked directly with CS. Mechanism study revealed that the increased adsorption performance is attributed to the large number of primary carboxyl and amine groups available on the surfaces of the CIAP-CS. The adsorption mechanism is based on ion exchange and chelating action, and the adsorption process is mainly chemisorption.

Sorption of copper onto low molecular weight chitosan derivative from aqueous solution

In this study, sorption of copper onto low molecular weight chitosan derivative was studied. Experimental parameters such as pH of the solution (A), temperature (B), dose of the sorbent (C), and concentration of solution (D) were considered. The statistical results indicated that the dose of sorbent (C) and Cu (II) concentration (D) influenced removal efficiency at 5% significance level. Also, some interactions such as ABCD, ACD, ABC and AC affected the removal process. The sorbent was characterized with FTIR, SEM and TG/DSC. Freundlich isotherm model was the best isotherm model. The kinetic study results correlated well with the pseudo-second-order model. The thermodynamic studies revealed that the nature of copper sorption was spontaneous and endothermic. Strong affinity of the sorbent for copper (II) was revealed by the Isothermal Titration Calorimetry (ITC) technique.

Simultaneous oxidation and adsorption of As(III) from water by cerium modified chitosan ultrafine nanobiosorbent

Since most existing arsenic removal adsorbents are difficult to effectively remove arsenite (As(III)), an urgent need is to develop an efficient adsorbent for removing As(III) from contaminated water. In this study, a novel ultrafine nanobiosorbent of cerium modified chitosan (Ce-CNB) with simultaneous oxidation and adsorption As(III) performance has been successfully developed. The resulting Ce-CNB with or without As(III) adsorption was characterized by FTIR, XRD, SEM, EDS, TEM, EMI and XPS analysis. Batch of adsorption experiments were performed to investigate the effects of various conditions on the As(III) adsorption. The adsorption behaviors were well described by the Langmuir isotherm and the pseudo-second-order kinetic model, with the maximum adsorption capacities of 57.5 mg g(-1). The adsorption mechanisms for As(III) were (i) formed monodentate and bidentate complexes between hydroxyl groups and arsenite; and (ii) partial As(III) oxidized to As(V) followed by simultaneously adsorbed on the surface of Ce-CNB. This novel nanocomposite can be reused while maintaining a high removal efficiency and can be applied to treat 5.8L of As(III)-polluted water with the effluent concentration lower than the World Health Organization standard, which suggests its great potential to remove As(III) from contaminated water.

Water soluble EDTA-linked chitosan as a zwitterionic flocculant for pH sensitive removal of Cu(ii) ion

Water soluble EDTA-linked chitosan was synthesized and applied to remove Cu(ii) utilizing its property of chelation and pH sensitive precipitation.

Sorption of heavy metal ions onto carboxylate chitosan derivatives--a mini-review

Chitosan is of importance for the elimination of heavy metals due to their outstanding characteristics such as the presence of NH2 and -OH functional groups, non-toxicity, low cost and, large available quantities. Modifying a chitosan structure with -COOH group improves it in terms of solubility at pH ≤7 without affecting the aforementioned characteristics. Chitosan modified with a carboxylic group possess carboxyl, amino and hydroxyl multifunctional groups which are good for elimination of metal ions. The focal point of this mini-review will be on the preparation and characterization of some carboxylate chitosan derivatives as a sorbent for heavy metal sorption.

Removal of cadmium from aqueous solution using low molecular weight chitosan derivative

A 2(3) factorial design was used to examine the sorption of Cd(2+) onto cross-linked low molecular weight chitosan pyruvic acid derivative. Three factors and two levels of solution pH (A) (6.0 or 10.0), temperature (B) (45 or 70 °C) and Cd(II) concentration (C) (1 or 3 mg/L) were considered. Batch mode system was employed with 0.05 g of the sorbent and 25 mL of Cd(II) solution. The efficiency of cadmium removal during an exposition time of 4h was then evaluated. The factors and their interaction effect on the cadmium removal efficiency followed the order: Cd(II) concentration > solution pH > interaction between solution pH and Cd(II) concentration>interaction between solution pH, temperature and Cd(II) concentration. Langmuir isotherm model was the best isotherm model. The Pseudo second order fitted well the kinetic data. The thermodynamic studies revealed the nature of the cadmium sorption.

Effective removal of azo-dye orange II from aqueous solution by zirconium-based chitosan microcomposite adsorbent

In this study, zirconium-based chitosan (CTS@Zr) microcomposite was prepared and employed as an efficient adsorbent for the removal of orange II dye from aqueous solution.

The Cooperative Effect in Dendronized Chitosan Microbeads

The present study evaluates the cooperative effects of dendronized chitosan microbeads with tris- and hexa-functionalized dendrons for capturing copper and for further use as catalysts. The dendronized microbeads were characterized by infrared spectroscopy, scanning electron microscopy, thermogravimetry, swelling capacity analysis, and atomic absorption spectroscopy. A correlation between the number and type of functional groups at the dendritic surface of the dendronized microbeads and the retention of copper highlights structural features of the cooperative effect. It is demonstrated that covalently bound dendrons can modulate the properties of chitosan, which has shown potential as a catalyst for the development of a novel materials.

Industrial applications of marine carbohydrates

Biomaterials have been used increasingly in various fields, such as drug delivery, imaging, and tissue engineering. The main reason justifying the widespread use of biomaterials relies on its valuable and low-cost source of new drugs. Current research goals are focused on identifying more potent and specific compounds with antitumor, immunomodulatory, antihyperlipidemic, anticoagulant, and antiviral activities. The increasing knowledge of structural analysis and chemical modifications enables the use of these marine carbohydrates in a newer way for the human welfare. This chapter focuses on the recent developments related to industrial and biomedical applications using chitin, chitosan, alginate, agar, and carrageenan derivatives and reports the main advances published over the last 10-15 years.

Collagen/cellulose hydrogel beads reconstituted from ionic liquid solution for Cu(II) adsorption

A novel adsorbent, biodegradable collagen/cellulose hydrogel beads (CCHBs), was prepared by reconstitution from a 1-butyl, 3-methylimidazolium chloride ([C4mim]Cl) solution. The adsorption properties of the CCHBs for Cu(II) ion removal from aqueous solutions were investigated and compared with those of cellulose hydrogel beads (CHBs). The CCHBs have a three-dimensional macroporous structure whose amino groups are believed to be the main active binding sites of Cu(II) ions. The equilibrium adsorption capacity (qe) of the CCHBs is greatly influenced by the collagen/cellulose mass ratio, and steeply increases until the collagen/cellulose mass ratio exceeds 2/1. The maximum adsorption is obtained at pH 6. The qe of Cu(II) ions increases with increased initial concentration of the solution. Based on Langmuir isotherms, the maximum adsorption capacity (qm) of CCHB3 (collagen/cellulose mass ratio of 3/1) is 1.06 mmol/g. The CCHBs maintain good adsorption properties after the fourth cycle of adsorption-desorption.

WITHDRAWN: Preparation and characterization of silica gel/chitosan composite for the removal of Cu(II) and Pb(II)

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