Study on the synthesis new type cross-linked chitosan porous resin and the absorption of Cd（Ⅱ）and Ni（Ⅱ）
2
Xu Qi* Lin KeChun Cang Hui yancheng institute of technology
college of chemical engine-
- eering and biological
Yan Cheng City China
Yao Cheng
Nanjing University of Technology
College
Nanjing China
2
Abstract:Chitosan is a versatile material, its derivatives has a wide range of applications. Chitosan resin absorption metal ions, becomes a research hotpot in recent years. A new chelating resin using chitosan as a base material was synthesized. Functional moiety of tetraethylenepentamine(TEPA) chemically bonded to the amino group of cross-linked chitosan (CCTS) through the arm of chloromethyloxirane, Ethylene glycol diglycidyl ether(EGDE) as the cross linker. The risen was holed by PEG-2000 to get porous-CCTS-TEPA.The amine resin showed a higher affinity towards the uptake of Cd（Ⅱ）and Ni（Ⅱ）from neutrality solution, where an uptake value of 123.54mg/g mg/g and 262.50mg/g, porous-CCTS-TEPA uptake value of 220.86mg/g mg/g and 315.0mg/g respectively, which was reported at pH 7 and room temperature.
Key Word: cross-linked chitosan tetraethylenepentamine Cd（Ⅱ） Ni（Ⅱ）absorption porous
1 Introduction
With the development of industry, the mount of produce and use of cadimium and nickel are continuously raise. Their compounds are widely used in galvanization, alloy manufacture, batteries and so on[1-2]. Heavy metal ions in natural water can bring harmful effect to human health, as well as to animals and plants in aquatic environment[3]. In human body, cadimium and nickel could harm many apparatus[4-5],they was pulled into carcinogen roll by International Agency for Research on Cancer(IARC) and national toxicology plan(NTP)[6].
Usual treatments for extraction of metal ions from effluents consist of flotation, solvent extraction, precipitation,ion-exchange and electrochemical separation,these methods sometimes suffer from problems such as excessive time requirements, high costs and production of highly toxic sludges[7].Chitosan was modified by compound which have amido and hydroxyl group to adsorb heavy metal ions is a hotspot in recent years[8-13]. Cross-linked chitosan (CCTS) was chemically functionalized with serine diacetic acid moiety through the extension arm of chloromethyloxirane, then the resin was modified with Tetraethylenepentamine, PEG-2000 as the porogen, study the absoption Cd（Ⅱ）and Ni（Ⅱ）capacity of etraethylenepentamine modified Cross-linked chitosan(CCTS-TEPA).
2 experiment
2.1 Reagents and materials
Chitosan(Shang Hai Lanji corporation). benzaldehyde(AR,Tian Jin Ke mi Ou Chemical Corporation).EGDE(AR,Shang Hai Ru Fa Corporation). Epichlorohydrin(AR, Sinopharm chemical regent Co.Ltd).PEG-2000(AR, Sinopharm chemical regent Co.Ltd). Cadmium standard solution(Sinopharm chemical regent Co.Ltd).Nickel standard solution(Sinopharm chemical regent Co.Ltd). CdCl2.5H2O(AR, Sinopharm chemical regent Co.Ltd). NiCl2.H20(AR, Sinopharm chemical regent Co.Ltd).Tetraethylenepentamine(AR,Sinopharm chemical regent Co.Ltd).
2.2 Instrumentations
Nicolet-670(NEXUS USA), Atomic AbsorptionSpectrometer(East & West analytical, AA-7003).SEM(KYKY-EM3900M).
2.3 Synthesis of CCTS-TEPA resin
Chitosan was reacted with benzaldehyde (80 g) in order to protect the amino group. The protected-chitosan was then filtered by using filter paper, and washed with ethanol to remove the remaining benzaldehyde, followed by washing with water.The cross-link structure was made by refluxing the protectedchitosan with EGDE (30 g). The product was then filtered and washed with ethanol andwater, respectively. The Schiff basewas cleaved to recover amino group by stirring the product in 0.5M hydrochloric acid (500 mL). The cross-linked chitosan was then filtered and washed three times with water. In the second step, the cross-linked chitosan was modified by introducing serine moiety through chloromethyloxirane extension arm. The cross-linked chitosan (5g) was reacted with chloromethyloxirane (10g) in order to attach the extension arm. The product was then filtered using filter paper, and washed each three times with ethanol and water to remove the remaining chloromethyloxirane[3]. The cross-linked chitosan, which has chloromethyloxirane as an extension arm, was then reacted with the Tetraethylenepentamine(TEPA). The synthesis
scheme of CCTS-TEPA is shown in Fig(1).
Put 100mLatolein,a little of span-80 and PEG-2000 into flask,stired 30mins, put CCTS-TEPA into the flask,stired 60mins, The product was then filtered using filter paper, and washed each three times with ethanol and water to remove the remaining atolein ,to get porous-CCTS-TEPA.
Fig（1）synthesis of CCTS-TEPA
2.4 ions absorption experiment
Put 0.2g CCTS-TEPA in the solution of Cd2+,stired 5h, the remaining powder was filtered using filter paper.And then repeated the experiment with the solution of Ni2+and porous-CCTS-TEPA.
3 result and discussion
3.1 Characteristics of CCTS-TEPA resin and CCTS-TEPA-Cd
The IR spectrum of CCTS-TEPA resin and CCTS-TEPA-Cd resin(which have been absorbed Cd2+)were shown in Fig(2), depicted several absorption peak removed.The overlapped absorption peak removed to low wavenumber from 3300cm-1.The transmogrification absorption peak removed to 1650cm-1 from 1600 cm-1,the phenomenon indicated the Cd-N bond was founded.The electron doublet moved to the Cd2+.The absorption peak was not evident changed in 1000 cm-1,it show that the absorption process did’t breach the glucose ring. The IR spectrum of CCTS-TEPA-Ni is similar with CCTS-TEPA-Cd. The transmogrification absorption peak removed to 1612cm-1 from 1600 cm-1,the phenomenon indicated the Ni-N bond was founded.
Fig(2) FT-IR spectra of CCTS-TEPA and CCTS-TEPA-Cd
3.2factor affecting the absorption prosess
3.2.1 pH affecting the absorption prosess
The absorption ability of the resin (CCTS-TEPA and porous-CCTS-TEPA) was mensurated at room temperature. Put 0.2g resin into the Cd2+ solution.The pH of the solutions were 2,3,4,5,6,7
It is calculate that CCTS-TEPA could absorb 123.54mg/g Cd2+ at room temperature and pH=7,while the porous-CCTS-TEPA could absorb 220.86mg/g Cd2+ in the same condition. Use Ni2+ repeat the experiment. It is calculate that CCTS-TEPA could absorb 262.50mg/g Cd2+ at room temperature and pH=7,while the porous-CCTS-TEPA could absorb 315.00mg/g Cd2+ in the same condition. The absorption ability of the resin was get the maximum in pH=7.In acidity condition, the electron doublet of N atom could found coordinate bond with H+ rather than metal ions.
3.2.2 time affecting the absorption prosess
Absorption rate of CCTS-TEPA was increased In the first hour of absorption prosess,and then the rate was decrease one hour by another. The rate of absorption and desorption was balanced in the firth hour,as shown in Fig(3).The absorption is a fast process. Fig(3) time affecting the absorption prosess
3.3 study of Langmuir isotherm absorption
The IR indicated that Cd(II) and Ni(II) was coordinated with CCTS-TEPA. The absorption motivity could influence absorption mechanism at some extent. Different absorption mechanism fitting absorption isotherm could measure the extent. Yuan Yan Chao[14-15] studied crosslinked chitosan resin absorbed Cu(II),Ni(II) and Co(II).Using the Langmuir isotherm fitting the behavior of crosslinked chitosan resin absorbed metal ions. The equation is:
Ce/Qe＝Ce/Qm＋1/Qmb…..(1)
Qm is the resin monolayer saturation adsorption quantity .Ce is balance concentration, Qe is balance adsorption quantity. The experiment fitting the absorption isotherm at 298K,308K,318K.
It is founded that the behavior of CCTS-TEPA absorbed Cd(II) and Ni(II) accord with Langmuir isotherm,as shown in Fig(4),Fig(5) and Table(1).
Fig（4）Langmuir line at different temperatures of Cd(II)
Fig（5）Langmuir line at different temperatures of Ni (II)
Table（1）Langmuir Isotherm Parameters for Cd(II)and Ni(II)with CCTS-TEPA
Temperature(K) Fitting Equations298 Cd(II) Ce/Qe=0.7723Ce+0.2958
308 Cd(II) Ce/Qe=0.7815Ce+0.2692
318 Cd(II) Ce/Qe=0.6884Ce+0.4214
298Ni(II) Ce/Qe=0.2202Ce+0.02061
308Ni(II) Ce/Qe=0.2126Ce+0.03382
318 Ni(II) Ce/Qe=0.2003Ce+0.06029
3.4 SEM analysis
Fig(6) is the SEM photo of CCTS-TEPA.It is not found holes in despite of high power.Fig(7) is the SEM photo of porous-CCTS-TEPA. The resin was pore-forming by PEG-2000. Obviously,there are many holes in the resin. It is make resin have large specific surface area.
Fig（6）SEM of CCTS-TEPA
Fig（7）SEM of porous-CCTS –TEPA
4 conclusion
(1) Chitosan resin modified with tetraethylenepentamine(CCTS-TEPA) can absorb Cd（Ⅱ）,Ni（Ⅱ）.The absorption ability could get best in neutral solution. It could absorb Cd（Ⅱ）and Ni（Ⅱ）123.54mg/g and 262.50mg/g respectively. The absorption behavior is a fast process and accord with Langmuir isotherm.
(2) PEG-2000 as the Pore-forming agent, it could get porous- CCTS-TEPA, the diameter of the hole is 10μm. It could absorb Cd（Ⅱ）and Ni（Ⅱ）220.86mg/g和315.00mg/g respectively. The
absorption ability was obvious enhanced.
References
[1]Han Lei,Zhang Heng Dong, Toxicity and harmful of lead and cadimium[J]. Journal of Occupational H ealth and Damage,2009,24(3):173-177.
[2]Ren Yibin,Yang Ke,Liang Yong. Harmfulness of Nickel in Medical Metal Materials[J]. Journal of Biomedical Engineering,2005; 22( 5)∶1067-1069.
[3]Lukman Hakim, Akhmad Sabarudin, Mitsuko Oshima,et al. Synthesis of novel chitosan resin derivatized with serine diacetic acidmoiety and its application to on-line collection/ concentration of trace elements and their determination using inductively coupled plasma- atomic emission spectrometry[J]. Analytica Chimica Acta,2007,588:73–81.
[4]Deng Xin,Wen Lu-lu,Shu Chi. Cadmium hazards to human health and the prevention and treatment research New[J]. National Medical Frontiers of China,2010,5(10):4-5.
[5]Wei Youhuan,Huang Qiuchan,Su Xiufang. Review on the Toxicological Effect and the Mechanism of Nickel to the Human Health[J]. Environmental Science and Management,2008,9:45-48.
[6]Heavy Metal Pollution Comprehensive Prevention Planning in the Forthcoming[J], Resource Recycling.2010,7:10-11.
[7]Asem A. Atia. Studies on the interaction of mercury(II) and uranyl(II) with modified chitosan resins[J]. Hydrometallurgy 2005,80:13-22.
[8]Lukman H,Akhmad S,Mitsuko O,Shoji M et.al. Synthesis of novel chitosan resin
derivatized with serine diacetic acid moiety and its application to on-line collection/concentration of trace elements and their determination using inductively coupled plasma-atomic emission spectrometry[J].Analytica Chimica Acta,2007,588:73–81
[9]Akhmad S,Mitsuko O,Toshio T,Lukman H et.al. Functionalization of chitosan with 3,4-dihydroxybenzoic acid for the adsorption/collection of uranium in water samples and its determination by inductively coupled plasma-mass spectrometry[J]. Analytica Chimica Acta,2007,581: 214–220
[10]Akhmad S, Narong L, Mitsuko O et. al. Sequential-injection on-line preconcentration using chitosan resin functionalized with 2-amino-5-hydroxy benzoic acid for thedetermination of trace elements in environmental water samples by inductively coupled plasma-atomic emission spectrometry[J]. Talanta,2007,72:1609–1617
[11] Asem A.Atia.Studies on the interaction of mercury(II) and uranyl(II) with modified chitosan resins[J].Hydrometallurgy.2005,80:13–22
[12] Yunhua Gao, Koji Oshita,Kyue-Hyung Lee, et.al.Development of column-pretreatment chelating resins formatrix elimination/multi-element determination by inductively coupled plasma-mass spectrometry[J]. Analyst, 2002, 127, 1713–1719
[13] Rosi Ketrin Katarina, Mitsuko Oshima, Shoji Motomizu. High-capacity chitosan-based chelating resin for on-line collection of transition and rare-earth metals prior to inductively coupled plasma-atomic emission spectrometry measurement[J]. Talanta 2009,79:1252-1259.
[14]Yuan Yan Chao,Zhang Ming Qiu,Rong Ming Zhi. Study on the Adsorption Behavior of Crosslinked Chitosan for Ni(II) [J]. ACTA CHIMICA SINICA.2005,63(10):1753-1758.
[15] Yuan Yan Chao,Zhu Zai Sheng,Zhang Ming Qiu. THE MECHANISM ON ADSORPTION Co2+ BY CROSSLINKED CHITOSAN RESIN[J]. ION EXCHANGE AND ADSORPTION, 2005, 21(5): 452 ~ 460.
2