|Nurul Shazlinie Abdul Shukor||Universiti Teknologi MARA|
|Azil Bahari Alias||Universiti Teknologi MARA|
|Mohd Azlan Mohd Ishak||Universiti Teknologi MARA|
|Raja Razuan Raja Deris||Universiti Teknologi MARA|
|Ali H. Jawad||Universiti Teknologi MARA|
|Khairul Adzfa Radzun||Universiti Teknologi MARA|
|Khudzir Ismail||- Universiti Teknologi MARA
Activated carbon produced from coconut shell and rubber seed pericarp has a great potential to be used as gas adsorbent. Most researchers, however, focus on producing activated carbon from one single biomass. Another option is to produce activated carbon from blending two different types of biomass with the strategy to reduce dependency on one type of biomass and sustain the production of activated carbon. Further, the adsorption capacity of the activated carbon produced from different blended biomass would be increased in comparison to single biomass. Most activated carbon is produced via physical activation using the conventional pyrolysis heating system, which is very time-consuming. In this study, activated carbon from biomass, namely coconut shell (CS-AC), rubber seed pericarp (RSP-AC), and their blends (CSRSP-AC) were successfully produced by using ZnCl2 as the chemical activating agent. The activation process was performed in a modified commercial microwave oven at the irradiation power of 600 W for 20 min. The single activated carbon and its blend were tested for their adsorption capacity for sulfur dioxide gas (SO2) using evolved gas analyzer (EGA). The single RSP-AC and CS-AC samples produced breakthrough time for SO2 adsorption at 23 min and 14 min, respectively. The longest SO2 breakthrough time for the blended activated carbon (CSRSP-AC) was achieved at 15 min with a ratio of 20:80 (CS:RSP) and was slightly longer than the individual CS-AC. The high amount of microporous RSP in the blend increases SO2 adsorption capacity. The presence of fly ash/Ca(OH)2 catalyst in the blended CSRSP-AC (20:80) further improves SO2 adsorption capacity with the breakthrough time achieving at 36 min at the adsorption temperature of 35oC. The SEM micrograph of blended CSRSP-AC with the addition of fly ash/Ca(OH)2 catalyst after SO2 adsorption showed that the pores were clogged with some of the samples agglomerated and clustered, indicating that both activated carbon and fly ash/Ca(OH)2 catalyst had interacted thoroughly with SO2 after the adsorption process.
Activated carbon; Coconut shell; Gas adsorbent; Microwave; Rubber seed pericarp; Sulfur dioxide
One of the emissions polluting the atmosphere is sulfur dioxide (SO2), which is mainly released by industries threatening the environment and human health (Uçar et al., 2009; Sumathi et al., 2010). The elimination of this gas from the stationary sources is important to prevent it from polluting the environment. Recently, many researchers have studied the removal of SO2 gas by using carbon-based materials (Bai et al., 2016; Sun et al., 2018; Shao et al., 2018).
In Malaysia, a high capacity of electricity is generated through the thermal power plants where the main source of fuel is supplied by burning coal. In recent years, about 2420 MW of electricity has been generated from Sultan Salahuddin Abdul Aziz Shah power station, Kapar, Selangor by using more than a hundred tons of coal for the national usage (Amin et al., 2013). However, an increase in Malaysia’s coal power plants leads to an increase in the formation of fly ash, which is a residue formed as a result of the combustion of bituminous coal (Ismail et al., 2007). This fly ash has a glassy, spherical shape with a very fine structure similar to that of cement. According to Wang and Wu (2006), the presence of fly ash has posed the industry the challenge of disposing and creating a more efficient recycling technique.
This work has studied the adsorption of SO2 on activated carbon, prepared from the coconut shell, rubber seed pericarp, and their blends. Activated carbon was prepared using the microwave irradiation technique. Previous researchers have reported the use of microwave heating in pyrolyzing the crude oil and other carbon materials (Leong et al., 2016; Yang & Ani, 2016). This study provides comprehensive data about the cleaning of SO2 gas by using activated carbon from blending the coconut shell and rubber seed pericarp. The blended activated carbon was utilized in the presence of coal fly ash to improve the efficiency of SO2 adsorption. The coconut shell and rubber seed pericarp have successfully been converted into well-developed activated carbon with microporous characteristics and used to adsorb SO2 (Shukor et al., 2017). The effect of four important parameters have been investigated, and these include the blending ratio of activated carbon (CS:RSP), mass loading of sample in combustion cell, adsorption temperature, and addition of fly ash/Ca(OH)2 toward SO2 adsorption. These parameters were chosen for investigation because of their significant influence on SO2 adsorption (Sumathi et al., 2010; Rubio & Isquierdo, 2010). Further, the surface morphology of adsorbent before and after adsorption was also carried out to understand the effect between surface chemistry of adsorbents on the adsorption process.
Adsorption capacity of SO2 on biomass activated carbon (CS-AC, RSP-AC) and their blends (CSRSP-AC) were tested and monitored by an evolved gas analyzer. The single microporous RSP-AC exhibits the longest SO2 breakthrough time of 23 min in comparison to the single CS-AC at 14 min. Among the blended samples, the 20:80 (CS:RSP-AC) was found to have the longest SO2 adsorption breakthrough time (C/Co) of 15 min. A high amount of RSP in the blended sample promotes a longer SO2 breakthrough time. The relationship between the SO2 breakthrough time and the adsorption temperature was analyzed, and the highest breakthrough time recorded was at 35oC with 29 min of adsorption breakthrough time. Increasing the adsorption temperature slightly reduces the SO2 adsorption capacity. The addition of fly ash/Ca(OH)2 catalyst that contains CaO and MgO with activated carbon increases the performance of adsorption capacity, where the breakthrough time was increased to 36 min. The SEM image showed that the porosity of adsorbent was reduced through the surface coverage by the reaction of the product, which means that the SO2 adsorption activity has been successful.
This research project was funded by the Ministry of Higher Education, Malaysia (MOHE) under the Fundamental Research Grant Scheme (FRGS), Grant No: FRGS/1/2017/TK10/UITM/02/11. The authors also acknowledge Universiti Teknologi MARA for providing facilities during the research work.
Amin, Y.M., Khandaker, M.U., Shyen, A.K.S., Mahat, R.H., Nor, R.M., Bradley, D.A., 2013. Radionuclide Emissions from a Coal-fired Power Plant. Applied Radiation and Isotopes, Volume 80, pp. 109–116
Bai, B.C., Lee, C.W., Lee, Y.S., Im, J.S., 2016. Metal Impregnate on Activated Carbon Fiber for SO2 Gas Removal: Assessment of Pore Structure, Cu Supporter, Breakthrough, and Bed Utilization. Colloids and Surfaces A: Physicochemical and Engineering Aspects, Volume 509, pp. 73–79
Belo, L.P., Elliott, L.K., Stanger, R.J., Spörl, R., Shah, K.V., Maier, J., Wall, T.F., 2014. High-Temperature Conversion of SO2 to SO3: Homogeneous Experiments and Catalytic Effect of Fly Ash from Air and Oxy-fuel Firing. Energy & Fuels, Volume 28(11), pp. 7243–7251
Dahlan, I., Mei, G.M., Kamaruddin, A.H., Mohamed, A.R., Lee, K.T., 2008. Removal of SO2 and NO Over Rice Husk Ash (RHA)/CaO-Supported Metal Oxides. Journal of Engineering Science and Technology, Volume 3(2), pp. 109–116
Idris, S.S., Rahman, N.A., Ismail, K., 2012. Combustion Characteristics of Malaysian Oil Palm Biomass, Sub-bituminous Coal and Their Respective Blends via Thermogravimetric Analysis (TGA). Bioresource Technology, Volume 123, pp. 581–591
Ismail, K.N., Hussin, K., Idris, M.S., 2007. Physical, Chemical and Mineralogical Properties of Fly Ash. Journal of Nuclear and Related Technology, Volume 4, pp. 47–51
Izquierdo, M.T., Rubio, B., 2008. Carbon-enriched Coal Fly Ash as a Precursor of Activated Carbons for SO2 Removal. Journal of Hazardous Materials, Volume 155(1-2), pp. 199–205
Jain, D., Khatri, C., Rani, A., 2011. Synthesis and Characterization of Novel Solid Base Catalyst from Fly Ash. Fuel, Volume 90(6), pp. 2083–2088
Karatepe, N., Orbak, ?., Yavuz, R., Özyu?uran, A., 2008. Sulfur Dioxide Adsorption by Activated Carbons Having Different Textural and Chemical Properties. Fuel, Volume 87(15-16), pp. 3207–3215
Lee, Y.W., Park, J.W., Choung, J.H., Choi, D.K., 2002. Adsorption Characteristics of SO2 on Activated Carbon Prepared from Coconut Shell with Potassium Hydroxide Activation. Environmental Science & Technology, Volume 36(5), pp. 1086–1092
Leong, S.K., Lam, S.S., Ani, F.N., Ng, J.H., Chong, C.T., 2016. Production of Pyrolyzed Oil from Crude Glycerol using a Microwave Heating Technique. International Journal of Technology, Volume 7(2), pp. 323–331
Liu, W., Adanur, S., 2014. Desulfurization Properties of Activated Carbon Fibers. Journal of Engineered Fibers & Fabrics, Volume 9(2), pp. 70–75
Rubio, B., Izquierdo, M.T., 2010. Coal Fly Ash Based Carbons for SO2 Removal from Flue Gases. Waste Management, Volume 30(7), pp. 1341–1347
Shao, J., Zhang, J., Zhang, X., Feng, Y., Zhang, H., Zhang, S., Chen, H., 2018. Enhance SO2 Adsorption Performance of Biochar Modified by CO2 Activation and Amine Impregnation. Fuel, Volume 224, pp. 138–146
Shukor, N.S.A., Ismail, K., Raja Deris, R.R., Alias, A.B., Ishak, M.A.M., 2017. Production and Characterisation of Single and Mixed Activated Carbons from Coconut Shell and Rubber Seed Pericarp using Microwave-induced Chemical Activating Agent. Materials Science Forum, Volume 889, pp. 209–214
Sumathi, S., Bhatia, S., Lee, K.T., Mohamed, A.R., 2010. Selection of Best Impregnated Palm Shell Activated Carbon (PSAC) for Simultaneous Removal of SO2 and NOx. Journal of Hazardous Materials, Volume 176(1-3), pp. 1093–1096
Sun, Y., Yang, G., Zhang, L., 2018. Hybrid Adsorbent Prepared from Renewable Lignin and Waste Egg Shell for SO2 Removal: Characterization and Process Optimization. Ecological Engineering, Volume 115, pp. 139–148
Uçar, S., Erdem, M., Tay, T., Karagöz, S., 2009. Preparation and Characterization of Activated Carbon Produced from Pomegranate Seeds by ZnCl2 Activation. Applied Surface Science, Volume 255(21), pp. 8890–8896
Wang, J., Meng, X., Chen, J., Yu, Y., Miao, J., Yu, W., Xie, Z., 2016. Desulphurization Performance and Mechanism Study by In-situ DRIFTS of Activated Coke Modified by Oxidization. Industrial & Engineering Chemistry Research, Volume 55(13), pp. 3790–3796
Wang, S., 2008. Application of Solid Ash Based Catalysts in Heterogeneous Catalysis. Environmental Science & Technology, Volume 42(19), pp. 7055–7063
Wang, S., Wu, H., 2006. Environmental-benign Utilisation of Fly Ash as Low-cost Adsorbents. Journal of Hazardous Materials, Volume 136(3), pp. 482–501
Wang, Z., Huan, Q., Qi, C., Zhang, L., Cui, L., Xu, X., Ma, C., 2012. Study on the Removal of Coal Smoke SO3 with CaO. Energy Procedia, Volume 14, pp. 1911–1917
Yang, A.L.C., Ani, F.N., 2016. Controlled Microwave-induced Pyrolysis of Waste Rubber Tires. International Journal of Technology, Volume 7(2), pp. 314–322
Yao, Z.T., Ji, X.S., Sarker, P.K., Tang, J.H., Ge, L.Q., Xia, M.S., Xi, Y.Q., 2015. A Comprehensive Review on the Applications of Coal Fly Ash. Earth-Science Reviews, Volume 141, pp. 105–121
Zainudin, N.F., Lee, K.T., Kamaruddin, A.H., Bhatia, S., Mohamed, A.R., 2005. Study of Adsorbent Prepared from Oil Palm Ash (OPA) for Flue Gas Desulfurization. Separation and Purification Technology, Volume 45(1), pp. 50–60