Separation of gold(III) ions from copper(II) and zinc(II) ions using thiourea–formaldehyde or urea–formaldehyde chelating resins

Thiourea–formaldehyde (TF) and urea–formaldehyde (UF) chelating resins were synthesized and these resins were used in the separation of gold(III) ions from copper(II) and zinc(II) base metal ions. In the experimental studies, the effect of acidity on gold(III) uptake and gold(III) adsorption capacities by batch method, and loading and elution profiles of gold(III) ions, gold(III), copper(II), and zinc(II), dynamic adsorption capacities and the stability tests of TF and UF resins by column method were examined. By batch method, the optimum acidities were found as pH 2 and 0.5M HCl, and gold(III) adsorption capacities in the solutions including copper(II) and zinc(II) ions were obtained as 0.088 and 0.151 meq Au(III)/g for UF and TF resins, respectively. On the other hand, by column method, the dynamic adsorption capacities were calculated as 0.109 meq Au(III)/g with TF, 0.023 meq Au(III)/g with UF, 0.015 meq Cu(II)/g with TF, 0.0057 meq Cu(II)/g with UF, and under 6.1 × 10^?5 meq Zn(II)/g with TF or UF. TF resin was more effective in the separation and the concentration of gold(III) ions from copper(II) and zinc(II) ions than UF resin. It was seen that sulfur atoms contributed the gold(III) adsorption comparing with oxygen atoms. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis,characterization, and metal adsorption properties of tannin–phenol–formaldehyde resins produced using tannin from dried fruit of Terminalia chebula (Aralu)

In this study, tannin extracted from Terminalia chebula (Aralu) was used to produce tannin–phenol–formaldehyde resins. They were produced to obtain resins with different tannin to phenol ratio in an attempt to optimize the ion exchange capacities of resins produced. The resins made were sulfonated to improve their properties further. Bivalent cations, such as Zn²⁺, Pb²⁺, Ca²⁺, Mg²⁺, and Cu²⁺, were used to estimate the adsorption properties of both unsulfonated and sulfonated resins. The glass transitions of representative resins were estimated using differential scanning calorimeter thermograms. Fourier transform infrared spectroscopic analysis was used to gauge changes on resins by sulfonation and adsorption of cations. The glass transition values of unsulfonated, sulfonated, and metal‐adsorbed sulfonated resins showed a similar increasing trend with the increase of phenol content in the resin. The glass transition temperature values reach a plateau beyond the tannin/phenol ratio of 1 : 0.5, indicating the formation of large molar masses facilitating entanglements beyond that ratio. The phenol ratio of 1 : 0.5 has shown the highest adsorption capacity for all the metal ions used. The highest adsorption capacity was shown for sulfonated tannin–phenol–formaldehyde resin with the tannin/phenol ratio of 1 : 0.5 for Pb²⁺, which is 0.610 meq/g. The adsorption equilibrium data obtained using the column technique were found fitting Freundlich isotherm. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Terpolymer resin–III: Synthesis and characterization of 8‐hydroxyquinoline–dithiooxamide–formaldehyde terpolymer resins

Terpolymer resins (8‐HQDF) were synthesized by the condensation of 8‐hydroxyquinoline (8‐HQ) and dithiooxamide (D) with formaldehyde (F) in the presence of acid catalyst and using varied molar ratios of reacting monomers. Terpolymer resins compositions have been determined on the basis of their elemental analysis and the number average molecular weights of these resins were determined by conductometric titration in non‐aqueous medium. Viscometric measurements in dimethyl formamide (DMF) have been carried out with a view to ascertain the characteristic functions and constants. The UV‐visible, FTIR, and proton nuclear magnetic resonance (H⁺ NMR) spectra were studied to elucidate the structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Chelating resins. V: Synthesis and characterization of chelating resins of formaldehyde-condensed phenolic Schiff bases derived from 4,4′-diaminodiphenyl sulphone with hydroxy benzaldehydes

The synthesis and characterization of a number of chelating resins having multiple functional groups capable of coordination to several metal ions is reported. The resins were synthesized by condensing Schiff bases derived from 4,4′-diaminodiphenyl sulphone and hydroxy benzaldehydes with formaldehyde and furfuraldehyde. The resins formed a number of polychelates with metal ions like Cu(II) and Ni(II). The Schiff bases, resins and the polychelates were charac-terized by IR, UV–vis., ¹H nuclear magnetic resonance spectra and thermogravimetric analysis. From the spectral data the possible coordination sites of the resins towards the metal ions were determined. The intrinsic viscosity of the resins was determined by viscometry in dimethylsulphoxide. The adsorption characteristics of the resins towards metal ions in dilute aqueous solutions were measured. The structure and the molecular geometry of the resins was observed to strongly influence the metal uptake behaviour, in addition to the influence of pH, temperature, particle size and metal ion concentration. Metallization of the resins significantly affected the thermal stability; the polychelates were found to be less stable than the resins. ©1997 SCI     

Synthesis and application of ion‐imprinted resin based on modified melamine–thiourea for selective removal of Hg(II)

A novel Hg(II) ion‐imprinted resin based on thiourea‐modified melamine was manufactured for selective elimination of Hg²⁺ from aqueous solutions. The polymerizable thiourea–melamine ligand together with its Hg(II) complex were extensively investigated using elemental analysis, Fourier transform infrared (FTIR) and ¹H NMR spectroscopies. The Hg(II) complex was used in a condensation polymerization in the presence of formaldehyde crosslinker and then the Hg(II) ions were leached out from the crosslinked polymeric network to finally leave the ion‐imprinted Hg‐PMTF resin. Both ion‐imprinted Hg‐PMTF and non‐imprinted resins were examined utilizing scanning electron microscopy and FTIR spectroscopy. The potential of the prepared resin for selective separation of Hg(II) ions from aqueous solutions was then evaluated by performing a series of batch experiments. Hg‐PMTF displayed an obvious rapid removal of Hg(II) ions with a pseudo‐second‐order kinetic pattern. In addition, the Langmuir adsorption isotherm model exhibited the best fit with the experimental data with comparatively high maximum adsorption capacity (360.5 mg g^?1). © 2015 Society of Chemical Industry     

Fe2+ and Fe3+ adsorption on 2‐vinylpyridine–divinylbenzene copolymers and acrylonitrile–methyl methacrylate–divinylbenzene terpolymers

The adsorption of Fe²⁺ and Fe³⁺ ions on 2‐vinylpyridine–divinylbenzene copolymer and acrylonitrile–methyl methacrylate–divinylbenzene terpolymer was investigated. In general, the adsorption of Fe²⁺ and Fe³⁺ in both resins increased with the enhancement of hydrochloric acid and metal concentration. The metal adsorption on the terpolymer increased sharply with the addition of small portions of ethanol, whereas the adsorption on the copolymer practically was not affected by the presence of the alcohol. An increase in temperature produced a small increase in iron adsorption for both resins. Fourier transform infrared spectra showed that nitrile and ester groups of the terpolymer did not suffer hydrolysis during metal adsorption, even for the highest HCl concentration and the highest temperature applied. A mechanism of iron adsorption through the ion exchange of chloride anions by tetrahedral [FeCl₄]^2? or [FeCl₄]^? anions is proposed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3905–3912, 2003     

The use of exhausted olive cake ash (EOCA) as a low cost adsorbent for the removal of toxic metal ions from aqueous solutions

The removal characteristics of cadmium (Cd(II)) and nickel (Ni(II)) ions from aqueous solution by exhausted olive cake ash (EOCA) were investigated under various conditions of contact time, pH, initial metal concentration and temperature. Batch kinetic studies showed that an equilibrium time of 2 h was required for the adsorption of Ni(II) and Cd(II) onto EOCA. Equilibrium adsorption is affected by the initial pH (pH₀) of the solution. The pH₀ 6.0 is found to be the optimum for the individual removal of Cd(II) and Ni(II) ions by EOCA. The adsorption test of applying EOCA into synthetic wastewater revealed that the adsorption data of this material for nickel and cadmium ions were better fitted to the Langmuir isotherm since the correlation coefficients for the Langmuir isotherm were higher than that for the Freundlich isotherm. The estimated maximum capacities of nickel and cadmium ions adsorbed by EOCA were 8.38 and 7.32 mg g⁻¹, respectively. The thermodynamic parameters for the adsorption process data were evaluated using Langmuir isotherm. The free energy change (ΔG°) and the enthalpy change (ΔH°) showed that the process was feasible and endothermic respectively. As the exhausted olive cake is discarded as waste from olive processing, the adsorbent derived from this material is expected to be an economical product for metal ion remediation from water and wastewater.     

Adsorption of Cr(III), Ni(II), Zn(II), Co(II) ions onto phenolated wood resin

In this study, phenolated wood resin was used an adsorbent for the removal of Cr(III), Ni(II), Zn(II), Co(II) ions by adsorption from aqueous solution. The adsorption of metal ions from solution was carried at different contact times, concentrations and pHs at room temperature (25°C). For individual metal ion, the amount of metal ions adsorbed per unit weight of phenolated wood resin at equilibrium time increased with increasing concentration and pH. Also, when the amounts of metal ions adsorbed are compared to each other, it was seen that this increase was order of Cr(III) > Ni(II) > Zn(II) > Co(II). This increase was order of Cr(III) > Ni(II) > Co(II) > Zn(II) for commercial phenol–formaldehyde resin. Kinetic studies showed that the adsorption process obeyed the intraparticle diffusion model. It was also determined that adsorption isotherm followed Langmuir and Freundlich models. Adsorption isotherm obtained for commercial phenol–formaldehyde resin was consistent with Freundlich model well. Adsorption capacities from Langmuir isotherm for commercial phenol–formaldehyde resin were higher than those of phenolated wood resin, in the case of individual metal ions. Original adsorption isotherm demonstrated the monolayer coverage of the surface of phenolated wood resin. Adsorption kinetic followed the intraparticle diffusion model. The positive values of ΔG° determined using the equilibrium constants showed that the adsorption was not of spontaneous nature. It was seen that values of distribution coefficient (K_D) decreasing with metal ion concentration in solution at equilibrium (C_e) indicated that the occupation of active surface sites of adsorbent increased with metal ions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2838–2846, 2006     

Metal ion retention properties of water‐insoluble polymers containing carboxylic acid groups

Crosslinked poly(acrylic acid), PAA, and poly(2‐acrylamidoglycolic acid), PAAG, were synthesized by radical polymerization. Both resins contain carboxylic acid groups. PAA at basic pH exists basically as an acrylate anion and PAAG shows three atoms or groups, carboxylic acid, hydroxyl, and amide groups, that can act as ion exchanger or chelating groups. Both resins are studied as adsorbents to trace metal ions from saline aqueous solutions and natural sea water and their properties by Batch equilibrium procedure are compared. The metal ions studied under competitive and noncompetitive conditions were Cu(II), Pb(II), Cd(II), and Ni(II). The effects of pH, time of contact, amount of resin, temperature, and salinity were studied. Resin PAA shows a high affinity (>80%) for Cu(II) and Cd(II) and resin PAAG shows also a high affinity for Ni(II), Pb(II), and Cd(II). By treatment of the metal ion‐loaded resin with 4M HNO₃ it is possible to recover completely the Cu(II) ions from resin PAA and Ni(II) and Pb(II) from resin PAAG. The metal ion retention properties were studied with natural sea water. For those natural sea waters containing Cu(II) and Cd(II), the resins showed a high affinity for Cd(II) ions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 697–705, 2006     

除镍离子交换树脂的优选及其效能的研究

为优选除Ni~(2+)交换树脂,采用电镀镍废水(Ni~(2+)的质量浓度为80 mg/L)研究了5种阳离子交换树脂对Ni~(2+)的吸附等温式和吸附动力学,考察了其对电镀镍废水中Ni~(2+)的吸附交换容量、吸附交换速率、再生性能以及废水中共存离子对树脂处理电镀镍废水效能的影响。结果表明,在120 min内5种阳离子树脂对Ni~(2+)的吸附基本达到平衡,吸附等温线均符合Freundlich吸附,吸附动力学均遵循准二级动力学方程;KP752和CH-90树脂对Ni~(2+)吸附交换容量分别为22.421和22.831 mg/g,吸附效果最好,并且2种树脂对Ni~(2+)的回收率都可达80%以上;共存的Ca~(2+)、Mg~(2+)会显著影响CH-90树脂吸附Ni~(2+)的效果,而对KP752树脂的影响较小。     

Selective separation and concentration of Pd(II) from Fe(III), Co(II), Ni(II), and Cu(II) ions using thiourea‐formaldehyde resin

Thiourea‐formaldehyde (TUF), a well‐known chelating resin, has been synthesized and it was used in the adsorption, selective separation, and concentration of Pd(II) ions from Fe(III), Co(II) Ni(II), and Cu(II) base metal ions. The composition of the synthesized resin was determined by elemental analysis. The effect of initial acidity/pH and the adsorption capacity for Pd(II) ions were studied by batch technique. The adsorption and separation of Pd(II) were then examined by column technique. FTIR spectra and SEM/EDS analysis were also recorded before and after the adsorption of Pd(II). The optimum pH was found to be 4 for the adsorption. The adsorption data fitted well to the Langmuir isotherm. The maximum adsorption capacity of the TUF resin for Pd(II) ions was found to be 31.85 mg g⁻¹ (0.300 mmol g⁻¹). Chelating mechanism was effective in the adsorption. Pd(II) ions could be separated efficiently from Fe(III), Cu(II), Ni(II), and Co(II) ions using TUF resin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Copolymer resin. VII. 8‐hydroxyquinoline‐5‐sulfonic acid–thiourea–formaldehyde copolymer resins and their ion‐exchange properties

8‐Hydroxyquinoline‐5‐sulfonic acid–thiourea–formaldehyde copolymer resins were synthesized through the condensation of 8‐hydroxyquinoline‐5‐sulfonic acid and thiourea with formaldehyde in the presence of hydrochloric acid as a catalyst and with various molar ratios of the reacting monomers. The resulting copolymers were characterized with UV‐visible, IR and 1H‐NMR spectral data, employed to determine the reactivity of monomers. The average molecular weights of these resins were determined with vapor pressure osmometry and conductometric titration in a nonaqueous medium. The chelation ion‐exchange properties were also studied with the batch equilibrium method. The resins were proved to be selective chelating ion‐exchange copolymers for certain metals. The chelation ion‐exchange properties of these copolymers were studied for Cu²⁺, Ni²⁺, Co²⁺, Pb²⁺, and Fe³⁺ ions. The study was carried out over a wide pH range and in media of various ionic strengths. The copolymers showed a higher selectivity for Fe³⁺ ions than for Cu²⁺, Ni²⁺, Co²⁺, and Pb²⁺ ions. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Analytical applications of newly synthesized copolymer resin derived from p‐aminophenol,dithiooxamide, and formaldehyde

A copolymer resin (p‐APDF) has been synthesized using the monomers p‐aminophenol, dithiooxamide, formaldehyde in 1 : 1 : 2M proportions in the presence of 2M HCl as catalyst. The structure of p‐APDF copolymer has been elucidated on the basis of elemental analysis and various physicochemical techniques, i.e., UV‐visible, FTIR, and ¹H‐NMR spectroscopy. The number average molecular weight of copolymer resin was determined by nonaqueous conductometric titration in DMF. Viscosity measurement were carried out in DMF indicate normal behavior. The prepared resin proved to be a selective ion exchange resin for some metal ions. The chelating ion exchange properties of this resin was studied for Fe(III) and Cu(II), Ni(II), Co(II), Zn(II), Cd(II), Pb(II) ions. A batch equilibrium method was used to study selectivity of metal ion uptake over a wide pH range and in media of various ionic strength. The resin showed a higher selectivity for Fe(III), Ni(II), Cu(II) ions than for Co(II), Pb(II), Zn(II), and Cd(II) ions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Chelating resins VI: Chelating resins of formaldehyde condensed phenolic Schiff bases derived from 4,4′‐diaminodiphenyl ether with hydroxybenzaldehydes—synthesis,characterization, and metal ion adsorption studies

Phenolic Schiff bases derived from o‐, m‐, and p‐hydroxybenzaldehydes and 4, 4′‐diaminodiphenyl ether were subjected to polycondensation reaction with formaldehyde. The resins were found to form polychelates readily with several metal ions. The materials were characterized by elemental analysis, GPC, IR, UV‐Vis, ¹H‐NMR, XRD, and thermal analyses like TG, DTG, and DSC studies. The ¹H‐NMR spectra of the resins provided evidence of polycondensation with well‐defined peaks for bridging methylene and terminal methylol functions. The metal‐ligand bonds were registered in the IR spectra of the polychelates. The thermal analysis data provided the kinetic parameters like activation energy, frequency factor, and entropy changes associated with the thermal decomposition. These data indicated the resins to be more stable than the polychelates. The DSC and XRD data indicated that the incorporation of metal ions significantly enhanced the crystallinity of the polymers. The resins could adsorb several metal ions from dilute aqueous solutions. Adsorption characteristics of the resins towards Cu(II) and Ni(II) were studied spectrophotometrically both in competitive and noncompetitive conditions. The effects of pH, contact time, quantity of the sorbent, concentration of the metal ions in a suitable buffer medium were studied. The resins were found to be selective for Cu(II) leading to its separation from a mixture of Cu(II) and Ni(II). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 967–981, 2000     

Utilization of peanut shells as adsorbents for selected metals

Peanut shells of mesh size 10–20 were modified by combinations of treatments following a 3² factorial design. Treatments consisted of either no wash, water wash or base wash followed by no modification or modification with 0.6 M citric acid or 0.6 M phosphoric acid. The nine samples were evaluated for their uptake of five metal ions (Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II)) from solution. The results were compared with metal ion adsorption by three commercial cation exchange resins, namely, Amberlite® 200, Amberlite® IRC 718 and Duolite® GT‐73. The percent of metal ions adsorbed per gram of adsorbent was significantly increased by each of the acid treatments, average values ranged from 19 to 34% compared with non‐acid treated samples at 5.7%. The percent of metal ions adsorbed for base‐washed samples were higher than water‐washed or unwashed shells. Interaction between wash and acid treatment was not significant for most of the experimental conditions used. Acid‐treated samples were as effective as Duolite® GT‐73 in the adsorption of Cd(II) and almost twice as effective in the adsorption of Zn(II) from solutions containing a single metal ion. In solutions containing multiple metal ions, citric acid samples were found to be most effective and selective for Cu(II) compared with Cd(II), Ni(II), and Zn(II). In general, phosphoric acid‐modified shells removed the most metals from solution for the experimental samples and were more effective in removing Cd(II) and Zn(II) than two of the three commercial resins. Acid‐modified peanut shells are promising as metal ion adsorbents. © 1999 Society of Chemical Industry     

Syntheses and properties of carboxymethyl chitosan/urea–formaldehyde snake‐cage resins

A series of novel snake‐cage resins were synthesized using carboxymethyl chitosan (CM‐CTS) as the snake resin and urea–formaldehyde resin (UF) as the cage resin. Such factors as the optimal synthesis conditions, content of the crosslinking agent, and sorption capacities for metal ions of the above‐mentioned resins were investigated. The experimental results show that these resins have appropriate swelling properties and good mechanical stability. They do not run off in water, HCl, and NaOH aqueous solutions. To form a stable network system, NH₄Cl was used as a crosslinking agent to crosslink urea and formaldehyde in synthesis. The sorption experiment showed that the sorption properties of the resins in the presence of the crosslinking agent NH₄Cl are better than those without a crosslinking agent. The investigation of the FTIR spectra indicated that the chelate groups, such as —OH, —CO and NHCH₂CO, in snake‐resin molecules participated in the coordination with the metal ions, but the —C?O bonds in the cage resin UF did not. The snake resin CM‐CTS in the snake‐cage resins was the major contributor of sorption. The sorption dynamics showed that the sorption was controlled by liquid film diffusion. The isotherms can be described by Freundlich and Langmuir equations. The saturated sorption capacities of the resins for Cu²⁺, Ni²⁺, Zn²⁺, and Pb²⁺ were 1.48, 0.78, 0.13, and 0.02 mmol g^?1, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 310–317, 2002; DOI 10.1002/app.10331     

Trace metal ion retention properties of crosslinked poly(4‐vinylpyridine) and poly(acrylic acid)

The crosslinked resins poly(4‐vinylpiridine) (PVPy) and poly(acrylic acid) (PAA) were obtained by radical polymerization. PVPy shows monodentate ligands and PAA at basic pH is basically as acrylate anion, which can contain end‐carboxylates groups or form a bridge acting as mono‐ or bidentate ligands. The retention properties for trace metal ions from saline aqueous solutions and natural seawaters of these two resins were investigated by Batch equilibrium procedure. The metal ions studied were Cu(II), Pb(II), Cd(II), and Ni(II). The following effects were studied: pH, contact time, amount of the adsorbent, temperature, and salinity. The resin PVPy showed a high affinity for Cd(II) and PAA for Cu(II) and Cd(II). The metal ions were determined in the filtrate by atomic absorption spectrometry. By the treatment of the loaded resin with 4M HNO₃, it was possible to remove completely the Cu(II) ions. The retention properties of the resins were studied for trace metal ions present in the natural seawaters. Both resins showed a high affinity for Cd(II) when the natural seawater contained Cu(II) and Cd(II). © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2908–2916, 2004     

Conversion of soybean oil into ion exchange resins: Removal of copper (II), nickel (II), and cobalt (II) ions from dilute aqueous solution using carboxylate‐containing resin

An ion‐exchange resin containing carboxylic acid groups was prepared by reaction of epoxidized soybean oil with triethylene tetramine, followed by hydrolysis of glycerides by using sodium hydroxide solution. The cation exchange capacity of the resins was determined to be 3.50 mequiv/g. The adsorption capacity for Cu²⁺, Ni²⁺, and Co²⁺ on the obtained resin at pH 5.0 was found to be 192, 96, and 78 mg/g, respectively. Effect of pH on the adsorption capacity for copper (II), nickel (II), and cobalt (II) ions were also studied. Cu²⁺, Ni²⁺, and Co²⁺ were adsorbed at a pH above 3. These metal ions adsorbed on the resin are easily eluted by using 1N HCl solution. The selectivity of the resin for Cu²⁺ from mixtures containing Cu²⁺/Co²⁺/Ni²⁺ ions in the presence of sodium chloride was also investigated © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2386–2396, 2002     

Two-step synthesis and characterization of urea–isobutyraldehyde–formaldehyde resins

Urea–isobutyraldehyde–formaldehyde (UIF) resins were synthesized from urea, isobutyraldehyde and formaldehyde using sulfuric acid as catalyst by two-step method. The effect of molar ratio of isobutyraldehyde to formaldehyde (n(I)/n(F)), molar ratio of aldehyde to urea (n(A)/n(U)), catalyst concentration and reaction time on the yield, hydroxyl value and softening point of UIF resins were investigated. The UIF resins were characterized by Fourier transform infrared spectroscopy (FT-IR), ¹H-nuclear magnetic resonance (¹H NMR), gel permeation chromatography (GPC) and thermogravimetric (TG). The results showed that the yield, hydroxyl value and softening point of the UIF resin were 76.5%, 90 °C and 32 mgKOH/g, respectively, when the molar ratio of urea to isobutyraldehyde to formaldehyde (n(U)/n(I)/n(F)) was 1.0/3.6/2.4, catalyst concentration was 6.0%, and reaction time in the second step reaction was 3.0 h. FT-IR and ¹H NMR results showed that α-H in isobutyraldehyde participated in the synthesis reaction of UIF resins, and the reaction was Mannich reaction. The amount of aldehyde groups in UIF resins increased with the increase of the amount of isobutyraldehyde. GPC results showed that the UIF resins had narrow molecular weight distribution and TG results indicated that the UIF resin had excellent heat resistance.     

Synthesis of functionalized phenolformaldehyde polymer resins by the reaction of 2,4‐dihydroxyacetophenone formaldehyde resin with various amines and their metal ion uptake properties

A series of functionalized phenolformaldehyde polymer resins have been synthesized by the reaction of 2,4‐dihydroxyacetophenone‐formaldehyde resin with the amines, such as ethanolamine, aminophenol, ethylenediamine, and propylenediamine in dichloromethane. The Schiffbase polymers were characterized by IR and ¹H‐NMR spectroscopic techniques. Thermal stabilities of the polymers were determined by TG and DTA studies. Heavy and toxic metal ions viz., Pb(II), Hg(II), Cd(II), and Cr(VI) have been removed using these polymer resins. Metal uptake efficiency, reusability, effect of pH, effect of time, and effect of initial concentration on the metal uptake were also studied. Amount of metal removed by the resin was determined using atomic absorption spectrophotometry. The retention properties were also tested under competitive conditions and were found to be depend strongly on the pH. Elution of metal ions were investigated in acid media. The uptake behaviour of the resins was approximately described by Freundlich's equation. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1501–1509, 2004