SYNTHESIS OF ZEOLITE FROM FLY ASH AND THE ADSORPTION OF Cu 2+ ION IN WATER SOLUTION

SYNTHESIS OF ZEOLITE FROM FLY ASH AND THE ADSORPTION OF Cu 2+ ION IN WATER SOLUTION Jumaeri 1,*, Sutarno 2, Eko Sri Kunarti 2 dan Sri Juari Santosa 2 1) Student of PhD Program, Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Yogyakarta, Indonesia 2) Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Gadjah Mada, Yogyakarta, Indonesia * Corresponding author, telp: 083838252885, email: jumaeri_unnes@yahoo.com ABSTRACT Zeolite has been synthesized from fly ash via hydrothermal reaction. Investigation of the adsorption of Cu 2+ ion in water solution using the synthesized zeolite was also performed. The synthesis was carried through a direct reaction of coal fly ash and NaOH solution. Coal fly ash from Tanjung Jati Power Plant (Jepara) was hydrothermally treated by NaOH solution in various concentrations (2, 3 and 4 M). A sodium hydroxide solution was mixed with coal fly ash powders in a Teflon vessel, which was placed in a stainless-steel autoclave. The autoclave was then heated in an oven at 120 0 C for 12 hours. After appropriate incubation periods, the autoclave was cooled and the solid phase was filtered out of the liquid. The product was thoroughly washed with distilled water then air-dried at 120 0 C for two hours. The qualitative tests were conducted by using Infrared Spectroscopy and X-Ray Diffraction. The adsorption test was carried out by batch adsorption of 25 ml of Cu 2+ solution and 0.1 g of the resulted solids from hydrothermal reaction. The result shows that concentration of NaOH, and hydrothermal time affecting the characteristics of hydrothermal products. The infrared spectrum and X-ray diffraction pattern showed that hydrothermal treatment was capable to produce solid material with zeolite structure. Adsorption of Cu 2+ on these synthetic zeolites was in the range of 11.49-17.845 mg/g, while the corresponding adsorption on fly ash was only 6.435 mg/g. It was confirmed that fly ash treated hydrothermally resulted in new material of zeolite-like, which was able to significantly remove Cu 2+ ion in water solution. Keywords: zeolite, fly ash, hydrothermal, Cu 2+ adsorption INTRODUCTION Along with the increasing of citizen growth and development in all area, the requirement of electricity energy in Indonesia or in the world more increased. The amount of coal fly ash generated by coalbased thermal power plants has been increasing at an alarming rate throughout the world [1]. In 2010 the coals consumptions for PLN (Perusahaan Listrik Negara) will increase from 40-45 million tons to 60-70 million tons [2]. By the need at least 60 million tons in 2010, it can be estimated will be produced as much as 4.72 million ton fly ash in Indonesia. The disposal of such a huge quantity of ash has become a pressing issue. One of the approaches is conversion fly ash to zeolite, which has vast application in ion exchanges, molecular sieves, catalyst, and adsorbent [3]. Coal is one of the major fossil fuels used in local power stations [4]. Some light minerals are not undergone reactions and are remained in the exhaust gas, and called fly ash [5]. The major components (approx 80%) in fly ash are amorphous aluminosilicate glasses, the conversion of fly ash to zeolite has also been proposed as a viable method [6]. Other crystalline minerals are also present in small quantities such as mullite, quartz and lime anhydrite [7]. Recently, the requirement of clean water becomes a seriously problem. This is aggravated again with the increasing of water pollution by industrial disposal, especially the waste water containing heavy metals, organics, and dyes. Therefore removal of toxic and heavy metal contaminates from wastewater is one of the most important environmental and economic issues [1]. Among the physicochemical treatment, process of adsorption is found to be highly effective, cheap and easy method. Research in recent years has been devoted to different types of low cost material such as some natural polymers like clay, Jumaeri, et al 365

ISSN NO. 1410-8313 The 2 nd International Conference on Chemical Sciences Proceeding natural zeolite, chitin, chitosan etc. In the present paper, we are using the waste material fly ash to produce zeolites through alkaline hydrothermal for the adsorption Cu 2+ in water solution. The hydrothermal process is a solvothermal process carried out in water solvent at moderate temperatures (100-300 0 C). In the procces, water serves two different functions; it is the solvent and the pressure transmitting medium [8]. The solvent properties of pure water are often not sufficient to dissolve substances for crystallization. Therefore, it is necessary to add a mineralizer, which able to increasing the solubility of the solute through the formation of soluble species that would not normally be present in the water. For oxide of silicate, the hydroxide of the alkali metals is often used. The sodium hydroxide in the reaction mixture acts as an activator and takes part in zeolite formation during hydrothermal process [9]. The hydrothermal reaction rate increase consitenly with the NaOH concentration [10]. EXPERIMENTAL SECTION Materials The coal fly ash samples were collected from Tanjung Jati Power Plant, Jepara, Indonesia. The elemental constituents of fly ash were determined using X-RF method. All of the chemical reagents used come from E- Merck. Instrumentation The main equipments were used in this work is following. Autoclave stainless steel with Teflon liner as reaction chamber, the electric sieves, glass apparatus, balance analytic, ph meter, electric shaker, Atomic Absorption Spectrometer Shimadzu,, XRD 6000 Shimadzu diffractometer, XRF Advant XP 502 Thermal ARL, and Shimadzu FTIR Spectrophotometer. Procedure Hydrothermal treatment Initially, the raw fly ash samples were first screened through an electric sieve of 100- mesh size. The unburnt carbon along with other volatile materials present in fly ash were removed by calcination at 600 (± 10) C for 2 h. Component of oxides in original fly ash were determined using XRF method. Fly ash samples were further treated with hydrochloric acid 1M to remove oxides of iron and the other metals to a certain extent. Hydrothermal treatment of fly ash with alkaline solution was carried out by Mimura s modified method [11]. A given concentration sodium hydroxide solution was mixed with fly ash in an inert Tefflon vessel which placed in stainless-steel autoclave. The fly ash/naoh ratio was taken 10 g fly ash/100 ml solution. The autoclave was then heated in an oven at temperature 120 0 C for 12 h. After appropriate periods, the autoclave was cooled and solid phase was filtered out of the liquid. The product was thoroughly washed with deionized water and dried in at 120 0 C for two hours. Characterization of sample and hydrothermal product Powder X-ray diffraction (XRD) patterns of the samples and hydrothermal product were obtained using diffractometer Shimadzu XRD- 6000, with Cu-Kα radiation at 40.0 kv and 30 ma. The samples were scanned from 2θ 5 o 70 in range. Meanwhile infrared spectroscopic analysis of the prepared samples was performed by Shimadzu FTIR, with pellet KBr method in wave number 400-4000 cm 1 in range. Adsorption of Copper Ion The contact time of optimum adsorption is determined by added 0.1 g adsorben into 25 ml solution that containing ion Cu 2+ 100 mg/l in an Erlenmeyer flash. This mxture is then agitated in mechanical shaker with the time variations: 0.5; 1; 1.5; 2; 2.5; and 3 h. Furthermore, adsorption Cu 2+ by coal fly ash and the hydrothermal product was carried out at the optimum contac time. A 0.25 g fly ash produced hydrothermal treatment o f ~ 100 mesh was suspended in a 25 ml of the water sample containing 100 mg/l Cu 2+ ion in Erlenmeyer flash. The suspension was shaken for 3 h in the mechanical shaker. Furthermore, the suspension was filtered by a Whatman paper- 42 and the clear supernatant was obtained. The concentration of Cu 2+ ion after the contact period was determined by AAS method. RESULTS AND DISCUSSION Chemical composition The fly ash samples from PLTU Tanjung Jati is colored grey-black, which exhibit unburnt carbon is present. After calcination at 600 0 C, the fly ash color change to colored brown. The chemicall composition of fly ash used in the present study were given in Table 1. From these result can be seen that the fly ash contain mainly SiO 2, Al 2 O 3, Fe 2 O 3 and the several oxides of Ca, Mg, Na, K etc. Therefore, it is allows to synthesized the low-si 366 Jumaeri, et al

zeolites with properties high exchange cation capacity of metals transition and ammonium ion, high selectivity for polar molecules and large pore volumes [3]. Table 1. Oxides component of fly ash No Component % weight 1. SiO 2 42,27 2. Al 2 O 3 22,33 3. CaO 7,60 4. MgO 3,41 5. Fe 2 O 3 12,45 6. MnO 0,0855 7. Na 2 O 2,04 8. K 2 O 2,05 9. CuO 0,0098 10. As 2 O 3 0,0038 11. P 2 O 5 0,294 12. SO 3 1,21 13. LOI 0,04 X-Ray Diffraction a b it is at 2θ (26.77; 35.83; 24.14) and mainly as amorphous phase, and the other as crystalline phase, (quartz, mulite and hematite). By using the hydrothermal treatment of fly ash were obtained a product which have new peaks and high crystalline. At the NaOH concentration 2M, with reaction time 12 h, the change of peaks are not significantly, the amorphous phase still dominant. The zeolite product contained the mixture of quartz phase and zeolite P. It was caused at solution NaOH in low concentration; they can not convert the quartz mineral to zeolite P. At the NaOH concentration 2M, the zeolite product show peaks of 2θ: 28,581 o and 2θ: 33,808 o. However, at the higher NaOH concentration (4M), formed the sharper peaks at 2θ 28,20 o ; 33,46 o ; 21,78 o ; 12,56 o and 17,77 o. The resulted XRD pattern is similar with obtained [12], where the hydrothermal product of fly ash is the mixture crystalline materials comprising quartz, hydroxl-sodalite, mullite and zeolite NaP. The peaks in the zeolite product show the existence of zeolite P. They are similiar with standard zeolite P as shown in (JCPDS, code: 39-0219). Infrared Spectra The infrared spectra for untreated and treated fly ash at various conditions were given in Figure 2. c d 10 20 30 40 50 60 70 Figure 1. XRD pattern of untreated fly ash (a), and various treated of fly ash with NaOH 2M (b); 3M NaOH (c); and 4M NaOH (d). Reaction condition: times 24 h, temperature 120 o C The XRD pattern for untreated and treated of fly ash at 120 0 C, at the conditions NaOH concentration 2; 3; and 4 M was given in Figure 1. The figure shows that the untreated fly ash exhibits three of main peaks, l l l l l l l Figure 2. IR Spectra of untreated fly ash (TJ), and various treated of fly ash with NaOH 2M, (a); 3M NaOH (b); and 4M NaOH (c). Reaction condition: times 24 h, temperature 120 o C Jumaeri, et al 367

ISSN NO. 1410-8313 The 2 nd International Conference on Chemical Sciences Proceeding The IR spectra of the untreated fly ash indicated a characteristic bands Si O or Al O(1033.5 cm -1 ), O H of H 2 O adsorption (3425.58 and 1620.21). The characteristic bands at 1033.5; 771.53 cm -1 indicated the stretching Si-O-Si, 470.63 cm -1 is bending vibration Si-O, and opening pore at 385.76 cm - 1. The similar result was obtained by Vucinic et al [13], where the main peaks of IR spectra of the used fly ash could be meet at 1/ 1075 cm - and 440 cm -. The infrared spectrum of all of sample is also overlapping of the fly ash phase and hydrothermal product vibration. The treated fly ash with NaOH 2 M, 3 M and 4 M provided the characteristic new peaks at (1080.14, 1002.98, 779.24)cm - and 501.49 (Fig. 2b,c,d). It was predicted as absorbance bands of vibration asymmetric stretching TO4. The broad bend at about 3400 cm -1 and a band at about 1640 are attributed to zeolite water in fly ash hydrothermal treated.the IR spectrum of hydrothermal product also indicated the presence of zeolite; characteristic band assigned to internal tetrahedral and external linkages were observed in the region 400 to 1200 cm -1. Similar spectra were also obtained by Mimura [11]. Adsorption of Copper ion The relation of contact time with amount of Cu 2+ ion adsorpted was given in Figure 3. Figure 4. Adsorption Cu 2+ ion on the zeolite product with NaOH treatment at concentration 2, 3 and 4M Figure 4 exhibits that the abilities of adsorption coal fly ash without treatments is less than the syntetic zeolite produced. Adsorption of Cu 2+ on synthetic zeolites is 11.49 mg/g - 17.845 mg/g in range, while adsorption on fly ash is 6.435 mg/g. It is proved that the treatment alkaline hidrotermal can increase the zeolite porosity produced. The larger NaOH concentration, the larger the adsorption ability of the zeolite produced. Therefore, the zeolite formation more effectively with increasing NaOH concentration. CONCLUSION Figure 3. Adsorption Cu 2+ ion on the various contac time. In the figure can be seen that the maximum adsorption Cu 2+ ion was achieved in 3 h. Furthermore, the adsorption of Cu 2+ ion in artificial waste was evaluated for the untreated fly ash and the synthetic zeolite from fly ash under the various condition were given in Figure 4. The alkaline hydrothermal reaction of fly ash can gives the various zeolite products. The hidrothermal products contained the mixture cystal, such as quartz, mullite, hydroxysodalite and Na-P. The adsorption ability of Cu 2+ in the sample solution for the product zeolite corresponded well to their properties of high cation exchange. The adsorption Cu 2+ for the treated fly ash reached 45.96; 53.83 and 71.74%, while the original fly ash only 25.74%. The zeolite formation more effectively with increasing NaOH concentration in the range 2 4 M. ACKNOWLEDGEMENTS We would like to acknowledge the financial support of Director of Research and Public Service Higher Education Directorate, National Education Department, according to Agreement Letter of Implementation Research Grand,No016/SP2H/PP/DP2M/III/2008, March 6 th 2008 368 Jumaeri, et al

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