Preparation and adsorption behavior for metal ions of cyclic polyamine derivative of chitosan

The new macrocyclic polyamine derivatives of chitosan were synthesized by reacting epoxy‐activated macrocyclic tetra‐amine with C6 hydroxyl or C2 amino group in chitosan. The obtained copolymers contain amino functional groups in its skeleton and secondary amines, and more polar hydroxyl groups. Elemental analysis, infrared spectra, and solid‐state ¹³C NMR analysis confirmed their structures. The adsorption behavior of the macrocyclic polyamine grafted chitosan for Ag⁺, Pb²⁺, Hg²⁺, and Cr³⁺ were investigated. The experimental results showed that the two novel derivatives of chitosan have high adsorption capacity and good selectivity for some metal ions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3018–3023, 2006     

Synthesis and evaluation of chitosan aryl azacrown ethers as adsorbents for metal ions

New azacrown ether chitosan derivatives (CTS–OC, CTS–NC) were synthesized by reaction of aryl mesocyclic diamine with the C6 hydroxyl group or C2 amino group in chitosan. Their structures were confirmed by elemental analysis, infrared spectra analysis, and X‐ray diffraction analysis. The adsorption and selectivity properties of the aryl azacrown ethers chitosan derivatives for Hg²⁺, Cd²⁺, Pb²⁺, Ag⁺, and Cr³⁺ were also investigated. The experimental results showed that the two chitosan–azacrown ethers have good adsorption capacity for Pb²⁺, Cd²⁺, and Hg²⁺. The adsorption capacity of CTS–OC are higher than that of CTS–NC for Pb²⁺ and Cd²⁺. The chitosan–azacrown ethers have high selectivity for the adsorption of Pb²⁺ and Hg²⁺ with the coexistence of Cd²⁺. The selectivity properties of CTS–OC are better than those of CTS–NC. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3093–3098, 2000     

Synthesis and characterization of macrocyclic polyamine derivative of chitosan

A novel macrocyclic polyamine derivative of chitosan was synthesized by a reaction between chitosan and epoxy‐activated macrocyclic polyamine. The copolymer that is obtained contains amino functional groups in its skeleton and secondary amine and more polar hydroxyl groups. Four types of analyses were used to characterize the chemical modifications of the chitosan: elemental, FTIR spectra, solid‐state ¹³C‐NMR, and X‐ray diffraction. The adsorption properties of the macrocyclic polyamine grafted chitosan for Ag⁺, Cu²⁺, Co²⁺, and Cr³⁺ were also investigated. The experimental results showed that the new macrocyclic polyamine derivative of chitosan has high adsorption capacity and good selectivity for Ag⁺ in the presence of Ag⁺, Co²⁺, and Cr³⁺. The selectivity coefficients were K = 6.16, K = 14.81, and K = 2.42, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 924–929, 2003     

Synthesis,characterization, and adsorption properties of chitosan azacrown ethers bearing hydroxyl group

Two new chitosan azacrown ethers bearing hydroxyl groups (CTS‐DH and CTS‐DO) were synthesized by the reaction of 3‐hydroxyl‐1,5‐diaza‐cycloheptane and 3‐hydroxyl‐1,5‐diaza‐cyclooctane with epoxy‐activated chitosan. Their structures were characterized by elemental analysis, infrared spectra analysis, and X‐ray diffraction analysis. The adsorption and selectivity properties of the hydroxyl azacrown ethers chitosan derivatives for Ag⁺, Cr³⁺, Cd²⁺, and Pb²⁺ were also investigated. The experimental results showed that the two novel chitosan azacrown ethers have good adsorption capacity for Ag⁺, and also showed that the grafted chitosan azacrown ethers have high selectivity for the adsorption of Ag⁺ in the presence of Pb²⁺ and Cd²⁺. The selectivity coefficients of CTS‐DH and CTS‐DO were K = 21, K = 42, K = 20.5, K = 41, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1793–1798, 2001     

Study of the synthesis of chitosan derivatives containing benzo‐21‐crown‐7 and their adsorption properties for metal ions

Three new chitosan crown ethers, N‐Schiff base‐type chitosan crown ethers (I, III), and N‐secondary amino type chitosan crown ether (II) were prepared. N‐Schiff base‐type chitosan crown ethers (I, III) were synthesized by the reaction of 4′‐formylbenzo‐21‐crown‐7 with chitosan or crosslinked chitosan. N‐Secondary amino type chitosan‐crown ether (II) was prepared through the reaction of N‐Schiff base type chitosan crown ether (I) with sodium brohydride. Their structures were characterized by elemental analysis, infrared spectra analysis, X‐ray diffraction analysis, and solid‐state ¹³C NMR analysis. In the infrared spectra, characteristic peaks of C?N stretch vibration appeared at 1636 cm^?1 for I and 1652 cm^?1 for II; characteristic peaks of N? H stretch vibration appeared at 1570 cm^?1 in II. The X‐ray diffraction analysis showed that the peaks at 2θ = 10° and 28° disappeared in chitosan derivatives I and III, respectively; the peak at 2θ = 10° disappeared and the peak at 2θ = 28° decreased in chitosan‐crown ether II; and the peak at 2θ = 20° decreased in all chitosan derivatives. In the solid‐state ¹³C NMR, characteristic aromatic carbon appeared at 129 ppm in all chitosan derivatives, and the characteristic peaks of carbon in C?N groups appeared at 151 ppm in chitosan crown ethers I and III. The adsorption and selectivity properties of I, II, and III for Pd²⁺, Au³⁺, Pt⁴⁺, Ag⁺, Cu²⁺, and Hg²⁺ were studied. Experimental results showed these adsorbents not only had good adsorption capacities for noble metal ions Pd²⁺, Au³⁺, Pt⁴⁺, and Ag⁺, but also high selectivity for the adsorption of Pd²⁺ with the coexistence of Cu²⁺ and Hg²⁺. Chitosan‐crown ether II only adsorbs Hg²⁺ and does not adsorbs Cu²⁺ in an aqueous system containing Pd²⁺, Cu²⁺, and Hg²⁺. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1886–1891, 2002     

Synthesis,characterization, and metal ions adsorption properties of chitosan–calixarenes (I)

Calixarene‐modified chitosans (CTS–CA‐I and CTS–CA‐II) were first synthesized by the reaction of chitosan (CTS‐NH₂) with 1,3‐bis‐chloroethoxyethoxy‐2,4‐dihydroxy‐p‐tert‐butylcalix[4]arene (CA‐I) or its benzoyl derivative (CA‐II). Their structures were characterized by infrared and X‐ray diffraction spectroscopy and scanning electron microscopy (SEM). The adsorption of Ni²⁺, Cd²⁺, Cu²⁺, Pd²⁺, Ag⁺, and Hg²⁺ by CTS–CA‐I and CTS–CA‐II was studied and the thermodynamic parameter of two calixarene‐modified chitosans toward Hg²⁺ was deduced. The adsorption properties of CTS–CA‐I and CTS–CA‐II were greatly varied compared with that CTS‐NH₂, especially with the adsorption capacity toward Ag⁺ and Hg²⁺, because of the presence of the calixarene moiety. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1139–1144, 2003     

Preparation and adsorption properties of metal ions of crosslinked chitosan azacrown ethers

The novel azacrown ether chitosan derivatives (CCAE‐I, CCAE‐II) were prepared by reaction between crosslinked chitosan with epoxy‐activated azacrown ethers. Their structures were confirmed by elemental FTIR spectra analysis and X‐ray diffraction analysis. The adsorption and selectivity properties of the crosslinked chitosan azacrown ethers for Pb²⁺, Cu²⁺, Cr³⁺, Cd²⁺, and Hg²⁺ were also investigated. The experimental results showed that they have high adsorption capacity for Cu²⁺, Cd²⁺, and Hg²⁺. The adsorption capacity of CCAE‐II is higher than CCAE‐I for Cd²⁺ and Hg²⁺. The selectivity properties of CCAE are better than chitosan and crosslinked chitosan. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3053–3058, 1999     

Chitosan N-benzyl sulfonate derivatives as sorbents for removal of metal ions in an acidic medium

We synthesized chitosan-based sorbents for the uptake of metal cations in acidic solutions. Chitosan was reacted with 2-formylbenzene sodium sulfonate and 4-formyl-1,3-benzene sodium disulfonate in the presence of NaCNBH₃ to yield N-benzyl mono- and disulfonate derivatives of chitosan. IR and NMR spectra confirmed the presence of benzyl sulfonate groups. The degrees of substitution of the monosulfonate chitosan derivatives were in the range of 80%, while those of disulfonate derivatives were about 50%. These sulfonate derivatives of chitosan were tested on the sorption of heavy metals Cd²⁺, Zn²⁺, Ni²⁺, Pb²⁺, Cu²⁺, Fe³⁺, and Cr³⁺. The sorption capacities for disulfonate compounds were better than for monosulfonate compounds. This phenomenon was attributed to the amphoteric character of the monosulfonate derivatives. To improve the capacity of adsorption of monosulfonate compounds, the amino groups of these compounds were protected by the benzyloxycarbonyl groups. The protection of amino groups of disulfonate derivatives by benzyloxycarbonyl also improved their sorption capacity. The resulting protected polymers were tested for sorption of heavy metals. Both protected polymers were more efficient than are the parent nonprotected polymers. The synthesized sulfonate derivatives of chitosan are especially adapted to the sorption of heavy metals from the acidic industrial effluents. © 1996 John Wiley & Sons, Inc.     

Study on the adsorption properties of novel crown ether crosslinked chitosan for metal ions

We first synthesized N‐benzylidene chitosan (CTB) by the reaction of benzaldehyde with chitosan (CTS). Chitosan‐dibenzo‐18‐crown‐6 crown ether bearing Schiff‐base group (CTBD) and chitosan‐dibenzo‐18‐crown‐6 crown ether (CTSD) were prepared by the reaction of 4,4′‐dibromodibenzo‐18‐crown‐6 crown ether with CTB and CTS, respectively. Their structures were confirmed by Fourier transform infrared spectral analysis and X‐ray powder diffraction analysis. These novel crown ether crosslinked CTSs have space net structures with embedded crown ethers and contain the double structures and properties of CTS and crown ethers. They have stronger complexation with and better selectivity for metal ions than corresponding crown ethers and CTS. Moreover, these novel CTS derivatives can be used to separate and preconcentrate heavy or precious metal ions in aqueous environments. From this practical viewpoint, we studied the adsorption and selectivity properties of CTB, CTBD, and CTSD for Ag⁺, Cu²⁺, Pb²⁺, and Ni²⁺. The experimental results showed that CTBD had better adsorption properties and higher selectivity for metal ions than CTSD. For aqueous systems containing Pb²⁺–Ni²⁺ and Pb²⁺–Cu²⁺, the selectivity coefficients of CTSD and CTBD were K/Ni²⁺ = 24.4 and K/Cu²⁺ = 41.4 and K/Ni²⁺ = 35.5 and K/Cu²⁺ = 55.3, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 29–34, 2002; DOI 10.1002/app.10180     

Synthesis and characterization of grafting β‐cyclodextrin with chitosan

Two new adsorbents [β‐cyclodextrin–chitosan (β‐CD–CTS) and β‐cyclodextrin‐6–chitosan (β‐CD‐6‐CTS)] were synthesized by the reaction of β‐cyclodextrin (β‐CD) with epoxy‐activated chitosan (CTS) and the sulfonation of the C‐6 hydroxyl group of β‐cyclodextrin with CTS, respectively. Their structures were confirmed by IR spectral analysis and X‐ray diffraction analysis, and their apparent amount of grafting was determined by ultraviolet spectroscopy. The adsorption properties of β‐CD‐CTS and β‐CD‐6‐CTS for p‐dihydroxybenzene were studied. The experimental results showed that the two new adsorbents exerted adsorption on the carefully chosen target. The highest saturated capacity of p‐dihydroxybenzene of β‐CD‐CTS and β‐CD‐6‐CTS were 51.68 and 46.41 mg/g, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 860–864, 2004     

Chemical modification of chitosan: Synthesis and characterization of chitosan‐crown ethers

Four novel Schiff‐type chitosan (CTS)‐crown ethers were synthesized through a reaction between ? NH₂ in CTS or crosslinked chitosan (CCTS) and ? CHO in 4′‐formylbenzo‐crown ethers, and four secondary‐amino‐type CTS‐crown ethers were prepared through the reduced reaction of NaBH₄, respectively. Their structures were characterized by elemental analysis, Fourier transform infrared (FTIR) spectra analysis, solid‐state ¹³C‐NMR analysis, and X‐ray diffraction (XRD) analysis. The elemental analysis results showed that the percentage of nitrogen in all CTS‐crown ethers were lower than that of CTS or CCTS. From the FTIR data of CTS, CCTS, and CTS‐crown ethers I–VIII, we saw that the characteristic peaks of C?N, N? H, and Ar appeared and that the characteristic peaks of pyranoside in the chain of CTS or CCTS were not destroyed. The XRD spectra demonstrated that CTS‐crown ethers I–VIII gave lower crystallinities than CTS or CCTS, which indicated that these compounds were considerably more amorphous than CTS or CCTS. In the solid‐state ¹³C‐NMR spectra, all of these CTS‐crown ethers had a particular peak of aromatic at 128 or 129 ppm, and the greatest difference between Schiff‐type CTS‐crown ethers and secondary‐amino‐type CTS‐crown ethers was that the Schiff‐type CTS‐crown ethers had the particular peak of C?N, which disappeared in secondary‐type CTS‐crown ethers. All these facts confirmed that the structures of CTS‐crown ethers I–VIII were as expected. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2221–2225, 2003     

Preparation and characterization of dihydroxyl mesocyclic diamine derivative of chitosan

The synthesis of a new dihydroxyl mesocyclic diamine grafting chitosan is presented. This derivative is formed by reaction of dihydroxyl azacrown ether with expoxy‐activated chitosan. The obtained copolymer contains amino functional groups in its skeleton and the secondary amine, and more polar hydroxyl groups. Elemental analysis, fourier transform infrared analysis, as well as solid‐state carbon‐13 nuclear magnetic resonance analysis were used to characterize chemical modifications of the chitosan. The adsorption properties of the dihydroxyl mesocyclic diamine grafted chitosan for Ag⁺, Pb²⁺, Cd²⁺, and Cr³⁺ were studied. The experimented results showed that the novel chitosan derivative has good adsorption capacity and high selectivity for Ag⁺ in the presence of Pb²⁺, Cd²⁺, and Cr³⁺, and its adsorption selectivity is better than that of chitosan. The selectivity coefficients were K = 12.25, K = 6.12, and K = 0.52, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2677–2681, 2002     

Synthesis and adsorption properties for metal ions of crosslinked chitosan acetate crown ethers

Two novel chitosan derivatives—crosslinked chitosan dibenzo‐16‐c‐5 acetate crown ether (CCTS‐1) and crosslinked chitosan 3,5‐di‐tert‐butyl dibenzo‐14‐c‐4 diacetate crown ether (CCTS‐2)—were synthesized by the reaction of crosslinked chitosan with dibenzo‐16‐c‐5 chloracetate crown ether and 3,5‐di‐tert‐butyl dibenzo‐14‐c‐4 dichloracetate crown ether with the intent of forming polymers that could be used in hazardous waste remediation as toxic metal‐binding agents in aqueous environments. Their structures were confirmed with elemental analysis, infrared spectral analysis, and X‐ray diffraction analysis. In the infrared spectra of CCTS‐1 and CCTS‐2, the characteristic peaks of aromatic backbone vibration appeared at 1595 cm⁻¹ and 1500 cm⁻¹; the intensity of the N H and O H stretching vibration in the region of 3150–3200 cm⁻¹ decreased greatly. The X‐ray diffraction analysis showed that the peak at 2θ = 20° decreased greatly in CCTS‐1 and CCTS‐2. The adsorption and selectivity properties of CCTS‐1 and CCTS‐2 for Pb²⁺, Cu²⁺, Cr³⁺, and Ni²⁺ were studied. Experimental results showed that the two crosslinked chitosan derivatives had not only good adsorption capacities for Pb²⁺, Cu²⁺, but also high selectivity for Pb²⁺, Cu²⁺ in the coexistence of Ni²⁺. For aqueous systems containing Pb²⁺, Ni²⁺, or Cu²⁺, Ni²⁺, CCTS‐1 only adsorbed Pb²⁺ or Cu²⁺. For aqueous systems containing Pb²⁺, Cr²⁺ and Ni²⁺, CCTS‐2 had high adsorption and selectivity properties for Pb²⁺. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2069–2074, 1999     

Studies on the synthesis and properties of hydroxyl azacrown ether‐grafted chitosan

The chitosan hydroxyl azacrown ether was synthesized by reaction of hydroxyl azacrown ether with epoxy‐activated chitosan. The C₂ amino group in chitosan was protected from the reaction between benzaldehyde and chitosan to form N‐benzylidene chitosan. After reaction with epichlorohydrin and azacrown ether, reacting O‐aryl mesocyclic diamine‐N‐benzylidene chitosan and dilute ethanol hydrochloride solution to obtain novel chitosan‐azacrown ether bearing hydroxyl removed the Schiff base. Its structure was confirmed with elemental analysis, FTIR spectra analysis, X‐ray diffraction analysis, and solid‐state ¹³C NMR analysis. Its static adsorption properties for Ag(I), Cd(II), Pb(II), and Cr(III) were also investigated. The experimental results showed that the hydroxyl azacrown ether grafted chitosan has good adsorption capacity and high selectivity for Ag(I) in the coexistence of Pb(II) and Cd(II), the selectivity coefficients of hydroxyl azacrown ether chitosan were K_Ag(I)/Pb(II) = 32.34; K_Ag(I)/Cd(II) = 56.12. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1838–1843, 2001     

Synthesis and characterization of chitosan derivatives carrying galactose residues

A series of water‐soluble chitosan derivatives, carrying galactose residues, were synthesized by using an alternative method in which the galactose groups were introduced into amino groups of the derivatives. First, hydroxyethyl chitosan (HECS) and hydroxypropyl chitosan (HPCS) were synthesized under alkaline conditions by using chitosan and propylene or chitosan and ClCH₂CH₂OH as the starting materials, respectively. Then lactobionic acid was added into the systems so as to form galactosylated HECS (Gal‐HECS) and galactosylated HPCS (Gal‐HPCS) with substitution degrees of 53 and 47%, respectively. Lactosaminated HPCS (Lac‐HPCS) and Lactosaminated HECS (Lac‐HECS) were obtained with substitution degrees of 42 and 38%, respectively, by the reductive amination of the mixtures of lactose and HECS or lactose and HPCS with potassium borohydride present in the reaction. The chemical structures of new chitosan derivatives were characterized by FTIR, ¹H NMR, ¹³C NMR, and elemental analysis. Some physical properties were also analyzed by wide angle X‐ray diffraction (WAXD) and differential scanning calorimetry (DSC). The novel chitosan derivatives carrying galactose residues may be used as additives for hepatic targeting delivery. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2161–2167, 2005     

Ligating behavior and metal uptake of N‐sulphonylpolyamine chelating resins anchored on polystyrene‐divinylbenzene beads

Amberlite XAD‐2 has been functionalized by coupling through –SO₂‐with ethylenediamine, propylenediamine, and diethylenetriamine to give the corresponding polyamine chelating resins I–III. The solid metallopolymer complexes of the synthesized chelating resins with Cu²⁺, Zn²⁺, Cd²⁺, and Pb²⁺ were synthesized. The polyamine derivatives and their metal complexes were characterized by elemental analysis, spectral (IR, UV/V, and ESR), and magnetic studies. The batch equilibrium method was utilized for using the chelating polyamines for the removal of Cu⁺², Zn⁺², Cd⁺², and Pb⁺² ions from aqueous solutions at different pH values and different shaking times at room temperature. The selective extraction of Cu⁺² from a mixture of the four metal ions and the metal capacities of the chelating resins were evaluated using atomic absorption spectroscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1839–1846, 2005     

Microwave preparation and adsorption properties of EDTA‐modified cross‐linked chitosan

A novel chitosan‐based adsorbent (CCTE) was synthesized by the reaction between epichlorohydrin O‐cross‐linked chitosan and EDTA dianhydride under microwave irradiation (MW). The chemical structure of this new polymer was characterized by infrared spectra analysis, thermogravimetric analysis, and X‐ray diffraction analysis. The results were in agreement with the expectations. The static adsorption properties of the polymer for Pb²⁺, Cu²⁺, Cd²⁺, Ni²⁺, and Co²⁺ were investigated. Experimental results demonstrated that the CCTE had higher adsorption capacity for the same metal ion than the parent chitosan and cross‐linked chitosan. In particular, the adsorption capacities for Pb²⁺ and Cd²⁺ were 1.28 mmol/g and 1.29 mmol/g, respectively, in contrast to only 0.372 mmol/g for Pb²⁺ and 0.503 mmol/g for Cd²⁺ on chitosan. Kinetic experiments indicated that the adsorption of CCTE for the above metal ions achieved the equilibrium within 4 h. The desorption efficiencies of the metal ions on CCTE were over 93%. Therefore, CCTE is an effective adsorbent for the removal and recovery of heavy metal ions from industrial waste solutions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Adsorption mechanism of copper ions in aqueous solution by chitosan–carboxymethyl starch composites

Based on the structural characteristics of chitosan (CTS) and carboxymethyl starch (CMS)， CTS–CMS composites were prepared by crosslinking. The composites had a plurality of reactive functional groups such as  NH₂,  NH₃⁺,  COOH, and  OH and are applied to the adsorption of Cu²⁺ in aqueous solution. The adsorption capacity and stability in acidic solution of the composites were preferable to that of raw material. The effects of temperature, contact time, initial concentration, and pH on the adsorption of Cu²⁺ were investigated. Infrared spectroscopy, scanning electron microscope–energy dispersive spectrometer, X-ray diffraction, and X-ray photoelectron spectroscopy were used to explore the adsorption mechanism. The experiment showed that chemisorption and physisorption coexisted in the adsorption process. It is promising to apply this adsorbent to remove the metal ions in wastewater. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48636.     

Simultaneous adsorption of phenol and Cu2+ from aqueous solution by activated carbon/chitosan composite

A multifunction adsorbent was synthesized by incorporating AC into CTS, and the ratio of AC to CTS was 1/1. The resultant was called activated carbon (AC)/chitosan (CTS) composite. The simultaneous adsorption of phenol and Cu²⁺ from aqueous solution onto AC/CTS composite was investigated by a batch procedure. The adsorption processes for both Cu²⁺ and phenol obeyed the pseudo second-order kinetic model. Phenol was prone to be adsorbed more quickly as compared with Cu²⁺ when they coexisted in solution. The adsorption behavior of both phenol and Cu²⁺ followed the Langmuir isotherm. The maximum adsorption capacities of phenol and Cu²⁺ were 34.19 mg/g and 74.35 mg/g at 293 K, respectively. No obvious competitive adsorption existed between phenol and Cu²⁺.     

Adsorption of Cd(II), Pb(II), and Ag(I) in aqueous solution on hollow chitosan microspheres

Cross‐linked chitosans synthesized by the inverse emulsion cross‐link method were used to investigate adsorption of three metal ions [Cd(II), Pb(II), and Ag(I)] in an aqueous solution. The chitosan microsphere, was characterized by FTIR and SEM, and adsorption of Cd(II), Pb(II), and Ag(I) ions onto a cross‐linked chitosan was examined through analysis of pH, agitation time, temperature, and initial concentration of the metal. The order of adsorption capacity for the three metal ions was Cd²⁺ > Pb²⁺ > Ag⁺. This method showed that adsorption of the three metal ions in an aqueous solution followed the monolayer coverage of the adsorbents through physical adsorption phenomena and coordination because the amino (? NH₂) and/or hydroxy (? OH) groups on chitosan chains serve as coordination sites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010