Proceedings of SEEP2014, 23-25 November 2014, Dubai-UAE THE POTENTIAL OF NATURAL ZEOLITES IN ENERGY RECOVERY TECHNOLOGY FROM WASTE PLASTIC AS Nizami 1,*, M Rehan 2, J Gardy 3, A Hassanpour 4, T Iqbal 5, Iqbal M.I. Ismail 6 1 Centre of Excellence in Environmental Studies (CEES), King Abdul Aziz University, Jeddah, Saudi Arabia; email: nizami_pk@yahoo.com 2 Centre of Excellence in Environmental Studies (CEES), King Abdul Aziz University, Jeddah, Saudi Arabia; email: dr.mohammad_rehan@yahoo.co.uk 3 Institute of Particle Science & Engineering (IPSE), School of Process, Environmental & Materials Engineering (SPEME), University of Leeds, Leeds, UK; email: Pmjlia@leeds.ac.uk 4 Institute of Particle Science & Engineering (IPSE), School of Process, Environmental & Materials Engineering (SPEME), University of Leeds, Leeds, UK; email: A.Hassanpour@leeds.ac.uk 5 Food and Biomaterial Research Group (FoBERG), Department of Bioprocess Engineering, University of Technology, Malaysia; email: tariq@cheme.utm.my 6 Center of Excellence in Environmental Studies (CEES), King Abdul Aziz University, Jeddah, Saudi Arabia; email: iqbal30@hotmail.com Abstract The energy consumption in Saudi Arabia has increased significantly in recent years due to a rapidly growing population and economic development. The current peak demand of electrcity is 55 GW and it is projected to become 120 GW in the year 2032. Fossil fuels are the only choice to meet the energy requirements. The government plans to double its energy generating capacity by 2020, of which around 85% will come from renewable resources. Natural zeolites are found abundantly in Saudi Arabia and have a significant role in the energy generation applications. Natural zeolites samples have been collected from the Jabal Shama occurrence near Jeddah city. All of the samples showed the standard zeolite group of alumina-silicate minerals with the presence of other elements such as Na, Mg and K etc. A highly crystalline structure is found in natural zeolites, which is critical when using in the energy applications as a process catalyst. However, there is a need of special milling and purification process to achieve homogeneous particle morphology and sizes in a range of sub-micron to nano-meter without impurities. This will significantly increase the surface area and pore volume of natural zeolites, thus improving their properties as a process catalyst and optimizer. The aim of this paper is to investigate the potential and utilization of naturally occurring zeolites in Saudi Arabia for pyrolysis of waste plastic to fuel oil. Key Words: natural zeolites; waste plastic; renewable resources, fuel oil; pyrolysis 1. INTRODUCTION The energy consumption in Saudi Arabia has increased upto 9 quadrillion British thermal units (Btu), due to a rapidly growing population and economic development. This placed the country to the world's 12 largest primary energy consumer [1]. Fossil fuels are the only choice to meet the energy requirements. About 60% of the energy demand is fulfilled from petroleum and the remaining comes from natural gas. The government is planning to increase its energy generating capacity of 55 gigawatts (GW) to 120 GW by 2020. About 85% of this planned generating capacity will come from renewable resources and only solar energy will covers 75% of it [1]. At the same time, the generation of municipal solid waste has increased upto 15 million tons per year with an average rate of 1.4 kg/capita/day [2]. The alarming fact is the waste collection and disposal at landfills without any treatment or energy recovery [3]. The problems to the public health and environment are occurring [4]. Currently, there is no energy recovery technologies of municipal solid waste existed in the Saudi Arabia. The waste plastic is the second largest and important waste stream with production of 2.7 million tons per year and 0.3 kg/capita/day [4]. Disposal of waste plastic in landfill is not suitable due to their slow degradation rates. Therefore, the waste plastic has to be recycled and recovered to minimize the environmental impact. The use of incineration technology has caused environmental problems of air pollution. Conventional mechanical recycling technologies such as sorting, grinding, washing and extrusion can recycle only 15-20% of all waste plastics. Beyond this level the plastics become very contaminated with extraneous materials such as soil, dirt, aluminium foils, food wastes and paper labels. The conversion of waste plastics into fuel oil through pyrolysis and catalytic Proceedings of SEEP2014, 23-25 November 2014, Dubai-UAE reforming is one of the promising methods for 70º with step size 0.0495 º at 35 sec per step. recycling these wastes [5]. Surface area, pore size and pore volume of the zeolite samples were measured by Micromeritics Catalytic reforming is a process to modify pyrolysis TriStar 3000 (UK) surface analyser. The zeolite fuel oil using synthetic or natural catalyst. The samples were degassed at 120 ºC for 24 h under a homogeneous and heterogeneous catalysts have vacuum of 10 mmHg in order to remove any been used for studying the catalytic cracking of moisture and gases from the samples prior to plastics. In general, heterogeneous catalysts are the analysis. The samples were then analysed at 77 K preferred choice due to their easy separation and using nitrogen gas. The Brunauer-Emmet-Teller recovery from the reacting medium [6]. A wide (BET) method was used to calculate the average variety of heterogeneous catalysts have been tested surface area. The particle size distributions (PSD) such as zeolite, silica alumina, and of the natural zeolite samples were measured by a fluid catalytic cracking. Each catalyst has a Malvern Mastersizer 3000 (UK). A few grams of each sample was fully suspended in water using different structure and composition which affects the fuel products [7]. However, the use of ultrasonic bath and then transferred into the commercial catalyst is expensive and the catalyst Mastersizer instrument. Physical properties of the cost is a key factor when compared with thermal suspended particles had to be entered at the outset. Hitachi scanning electron microscopy (SEM) was pyrolysis. Therefore, utilization of natural zeolites used to capture the particle size and morphology of available abundantly in Saudi Arabia can zeolite samples. The energy dispersive spectrometer significantly reduce catalyst cost. Zeolitic tuffs are (EDS) was used to determine the percentage of the available on a large scale at the Shama Harrat elements in the examined area of the zeolite (volcanic pyroclastics), ~ 150 km south of Jeddah. samples using an X-ray beam. BET surface analysis and pore volume measurements of natural zeolite There is no pyrolysis facility in the country for samples were performed according to the converting waste plastic into fuel oil. Similarly, the multipoint nitrogen adsorption-desorption method natural zeolites are not characterized for their at 77.3 K using Micromeritics TriStar 3000 (UK) potential role as a process catalyst in the pyrolysis surface analyser and results are shown in table 1. facility. Therefore, their physical and chemical SEM samples were prepared by making a characteristics are critical for catalytic reforming homogeneous suspension of zeolite powder process. The aim of this paper is to investigate the samples in acetone using ultrasonic bath. Few drops potential and utilization of naturally occurring of this suspension were then dropped onto the SEM zeolites in Saudi Arabia for pyrolysis of waste sample stubs and later transferred to a zone SEM plastic to fuel oil. cleaner in order to remove any contaminants by using UV radiation at pressure 1 Pa for 10 mins. 2. MATERIALS AND METHODS Once the cleaning of samples was done, the sample Natural zeolites samples have been collected from ~ holders were then transferred to the SEM 1.2 km2 area at the Jabal Shama occurrence which instrument where the imaging of samples, EDS, and is located some 100 km to the south of Jeddah city. mapping were taken and saved on the attached PC These natural zeolites have been characterized to for further analysis. study their potential use in energy-related applications. These samples were prepared by crushing and sieving before detailed chemical and 3. RESULTS AND DISCUSSION The FT-IR spectra of the natural zeolite samples physical analysis. Fourier transform infrared spectroscopy (FT-IR) spectra of the zeolite samples were recorded for structural analysis (Figure 1). The spectra for all samples showed very similar were obtained using FT-IR Perkin Elmer's, UK. A minimum of 32 scans were performed at average absorption bands position and intensities, indicating -1 signal of IR with a resolution 4 cm in the ranges of the overall structure of all samples contain same 500 to 4000 cm-1. Bruker D8 X-ray diffraction functional groups. The main bands with largest (XRD) was used to determine the crystal structure intensity present in the 1000-1020 cm-1 range of all and purity of natural zeolite samples taken from samples is referred to Si-O-Si and Si-O-Al vibrations, whilst the other three clear bands in 547different site locations. The D8 was operated with 549, 591-593 and 788-790 cm-1 ranges can be Cu radiation at 30 kV and 45 mA. Each zeolite largely attributed to different Al-O and Si-O sample was scanned from 2ϴ angel range of 5º to Proceedings of SEEP2014, 23-25 November 2014, Dubai-UAE vibrations. Additionally, the broad stretching contents (Figure 2). This high crystallinity feature between 3680-4000 cm-1 represent the vibrations of plays an important role in the zeolite applications, OH groups (Figure 1). including energy-related applications. The surface area and pore volume are key characteristics of any material that has applications involving its surface and porosity such as zeolite catalysts. The highest values of surface area and pore volume of different samples were 3.1 m2 g-1 and 0.01 cm3 g-1 respectively. Figure 1: FT-IR spectra of the natural zeolite The XRD patterns have been indexed using the reference data files from ICDD-PDF database. The XRD diffraction peaks of different samples matched with the following reference pattern.         From particle size distribution (PSD), it was found that all zeolite samples exhibit polydisperse particle size distributions, though with some differences in the distribution shifts. The average particle sizes ranged from around 0.4 - 830 µm. This polydisperse nature and larger particle sizes are also thought to be the reasons for obtaining relatively lower surface area and pore volumes of these natural zeolites. Counts Z1F 500000 Anorthoclase (potassium sodium aluminum silicate, (Na, K) (Si3Al) O8) with reference code 00-009-0478. Sillimanite (aluminum oxide silicate, Al2 (SiO4) O), with reference code 04-013-1827 Cristobalite (silicon oxide, SiO2) with reference code 04-008-7742. Aluminum oxide (Al2O3) with reference code 04-004-5290. Orthoclase (potassium aluminum silicon oxide, KAlSi3O8) 04-009-3610. Albite (sodium aluminum silicate, Na (Si3Al) O8) with reference code 00-010-0393. Quartz (silicon oxide, SiO2) with reference code 01-085-0865. Potassium aluminum silicon oxide, (KAlSi3O8) with reference codes 04-009-3610. The XRD patterns (Figure 2) do confirm that all samples are belong to zeolite group of aluminasilicate minerals with presence of other elements such as Na, Mg and K etc. However, the variation in the main peak positions and intensities indicate that the overall structures, chemical compositions and the amount of impurities of all samples are slightly different. It is observed that the nature of the peaks and minimum background of XRD patterns indicate that these natural zeolites are of high crystalline nature with little amorphous 0 Z2F 800000 600000 400000 200000 0 Z3F 600000 400000 200000 0 10 20 30 40 50 60 Position [°2Theta] (Copper (Cu)) Figure 2: XRD patterns of the natural zeolites samples Figure 3: PSD of the natural zeolite The SEM images also reveal polydisperse nature of particle size and morphology distributions, as noticed from the PSD analysis (Figure 4). These features are directly dependant on the milling Proceedings of SEEP2014, 23-25 November 2014, Dubai-UAE process used and therefore can be optimized. The From BET, PSD and SEM analysis, it is concluded SEM images show some smaller particles with that there is a need of using a special milling irregular shapes in the sub-micron size range. process for crushing the natural zeolites to achieve However, most of the particles are in micron sizes homogenious particle morphology and sizes in a or agglomerates. Some porous nature and layering range of sub-micron to nano-meter. This will surface features can be seen in the SEM images significantly increase the surface area and pore (Figure 4). Therefore, higher resolution TEM volume of natural zeolites, thus improving their analysis is required to have detailed observation properties for optimized applications. and confirmation of the pores and crystal fringes of these natural zeolite materials. Element Wt % O Na Mg Al Si S K Ca Ti Fe Total: 57.22 2.20 0.59 7.00 26.71 0.37 2.68 0.47 0.22 2.54 100.00 Wt % Sigma 0.24 0.08 0.06 0.10 0.18 0.05 0.08 0.06 0.07 0.15 Figure 5: EDS of the natural zeolite sample. Figure 4: SEM images of the natural zeolite samples The quantitative analysis of natural zeolite samples was performed by SEM-EDS (Figure 5). Zeolites are generally a group of alumina-silicate minerals that can accommodate a wide variety of cations such as K+, Na+, Ca2+ in their porous structures. The EDS data confirms that the samples studied are the types of zeolites by showing the high concentrations of key elements such as Al, Si and O together with the presence of other elements such as Na, Mg, S, K, Ca, Ti, Fe, in smaller quantities. Different types of natural and synthetic zeolites have different Si/Al ratios depending on their chemical compositions, structures and impurities. The EDS results showed some differences in the amount of each element present in all samples (Figure 5). The range of Si/Al ratio was found 3.86.3. This also confirms, as found in FT-IR and XRD analysis, that there are some differences in the Proceedings of SEEP2014, 23-25 November 2014, Dubai-UAE John Wiley & Sons, Ltd: Changsha, P.R. China. p. crystal structures and the presence of other 729-755. elements and impurities in natural zeolite samples. 4. CONCLUSION All of the samples showed the standard zeolite group of alumina-silicate minerals with the presence of other elements such as Na, Mg and K etc. A highly crystalline structure is found in natural zeolites, which is critical when using in the energy applications as a process catalyst. However, there is a need of special milling and purification process to achieve homogeneous particle morphology and sizes in a range of sub-micron to nano-meter without impurities. This will significantly increase the surface area and pore volume of natural zeolites, thus improving their properties as a process catalyst and optimizer. References [1] US Energy Information Administration (USEIA). Country Analysis Brief: Saudi Arabia. 2014. Available from : http://www.eia.gov/countries/cab.cfm?fips=sa [2] Ouda O. K. M., Cekirge H. M., Raza S.A. 2013. An assessment of the potential contribution from waste-to-energy facilities to electricity demand in Saudi Arabia. Energy Conversion and Management, 75: 402-406. [3] Gharaibeh E. S., Haimour N. M and Akash, B. A. 2011. Evaluation of Current Municipal Solid Waste Practice and Management for Al-Ahsa, Saudi Arabia, Int. J. of Sustainable Water and Environmental System, 2: 103-110. [4] Khan M. S. M and Kaneesamkandi Z. 2013. Biodegradable waste to biogas: renewable energy option for the Kingdom of Saudi Arabia. International Journal of Innovation and Applied Studies, 4 (1): 101-113. [5] Yuan, X., Converting Waste Plastics into Liquid Fuel by Pyrolysis : Developments in China, in Feedstock Recycling and Pyrolysis of Waste Plastics, J. Scheirs and W. Kaminsky, Editors.2006, [6] Aguado, J., D.P. Serrano, and J.M. Escola, Catalytic Upgrading of Plastic Wastes, in Feedstock Recycling and Pyrolysis of Waste Plastics, J. Scheirs and W. Kaminsky, Editors. 2006, John Wiley & Sons, Ltd: Mostoles, Spain. p. 73110. [7] McCusker, L.B. and C. Baerlocher, Zeolite Structures. 3rd Revised Edition ed. Introduction to Zeolite Science and Practice, ed. G. Centi. Vol. 2. 2007, Zurich, Switzerland: Elsevier B.V. 13-38.