ADSORPTION AND STRIPPING OF ETHANOL FROM AQUEOUS SOLUTION USING SEPABEADS207 ADSORBENT

Transcription

1 ADSORPTION AND STRIPPING OF ETHANOL FROM AQUEOUS SOLUTION USING SEPABEADS207 ADSORBENT M A ZIN ABDULHUSSEIN BEDEN U N IV ERSITI TEK N O L G I M ALAYSIA

2 ADSORPTION AND STRIPPING OF ETHANOL FROM AQUEOUS SOLUTION USING SEPABEADS207 ADSORBENT M A ZIN ABDULHUSSEIN BEDEN A dissertation subm itted in fulfillm ent of the requirem ents for the aw ard of the degree of M aster of E ngineering (Chemical) Faculty of Chem ical E ngineering U niversiti Teknoiogi M alaysia JANUARY 2015

3 To my beloved family

4 ACKNOWLEDGEMENT I would like express my sincere gratefulness to Allah for giving me strength and wisdom in whole my studying. Also I want to take this opportunity to introduce my gratefully acknowledge to my supervisors Dr. MUHAMMAD ABBAS AHMAD ZAINI and Dr. TUAN AMRAN TUAN to help me in this work. Their dedication, skillful guidance, helpful suggestions and encouragement made me able to deliver a dissertation in an appreciable quality and standard, also I want to introduce my thanks to Dr. UMI AISAH to help me in first part of the thesis. Deep appreciation I want to introduce to my family especially my dear wife to give me the hope and concentrate on my study. I owe my special thanks to my friend Safaa Abdulhussein and to lab. mates Mr. Mohammad Latfi, Mr. Ahmad Bukhairy, Mr. Mohammed Rafiza, Mr. zulkifli, Miss.Saadiah, Mr.Mohamad Halim and Miss. Aishah for their kindness, helping me and sharing their experience. Great thanks to all staff of chemical engineering department to support and advise me to finalize my project.

5 ABSTRACT There is a problem of increasing of CO2 and CO in environment from the use of fossil fuel. Ethanol is a good alternative fuel or additive to gasoline to improve octane number, using ethanol will decrease CO and CO2 emissions. For these reasons, production of ethanol by fermentation is a promising solution. This work aimed to evaluate suitable technique of separation using adsorption method. Best conditions of adsorption and stripping processes were studied in this work. The ethanol solution with 10wt% concentration, i.e., similar to the product of fermentation process was used as feed. The separation was occurred in adsorber tube containing polymer Sepabeads207 at different temperatures (20-40 C), also (ph) (4-7), time of adsorption (5-25 minutes). Also time of stripping (desorption) was studied between 15 and 35 minutes at different temperatures of air (80-95 C). The evaporated ethanol was condensed by cold water and the concentration of liquid ethanol was measured using refractometer and gas chromatography. The results show the best conditions for adsorption process are: time = 5 minutes; temperature = 20 C and ph= 4, while the best conditions for striping process are: time = 15 minutes and temperature = 80 C. By applying the best conditions for both adsorption and stripping processes, ethanol concentration of 46wt% was able to be obtained. The adsorbent capacity of Sepabeads207 is 0.22g ethanol/g adsorbent, while the adsorbent selectivity is 7.75 g eth an ol/ g w ater ( adsorbed) the g e th a n o l/g w ater (original so lu tio n ) efficiency of adsorbent is 100%. From this study can be concluded that using of Sepabeads207 to adsorb ethanol in static solution better than continues with applying best conditions.

6 ABSTRAK Terdapat masalah dengan peningkatan CO2 dan CO dalam persekitaran hasil daripada penggunaan bahan api fosil. Etanol adalah pilihan bahan api yang baik atau sebagai bahan tambah dalam petrol untuk meningkatkan nombor oktana, penggunaan etanol akan mengurangkan pelepasan CO dan CO2. Justeru, penghasilan etanol melalui penapaian merupakan bakal jalan penyelesaian. Kajian ini bertujuan untuk menilai teknik pemisahan yang sesuai dengan kaedah penjerapan. Keadaan terbaik proses penjerapan dan pelucutan telah dikaji. Larutan etanol berkepekatan 10wt%, iaitu kepekatan yang sama dengan produk proses penapaian digunakan sebagai suapan. Pemisahan berlaku dalam turus penjerapan yang mengandungi polimer Sepabeads207 pada suhu (20-40 C), juga ph (4-7), dan masa penjerapan (5-25 minit) yang berbeza. Juga masa pelucutan (penyahjerapan) dikaji di antara 15 dan 35 minit, dan pada suhu udara yang berbeza (80-95 C). Etanol tersejat telah dicairkan dengan air sejuk dan kepekatan cecair etanol diukur dengan refraktometer dan gas kromatografi. Keputusan menunjukkan keadaan terbaik untuk proses penjerapan ialah: masa = 5 minit; suhu = 20 C dan ph = 4, manakala keadaan terbaik untuk proses pelucutan ialah: masa = 1 5 minit dan suhu = 80 C. Dengan menggunakan keadaan terbaik untuk kedua-dua proses penjerapan dan pelucutan, kepekatan etanol 46wt% telah diperolehi. Muatan penjerap Sepabeads207 ialah 0.22g etanol / g penjerap, manakala pemilihan penjerap ialah 7.75 dan kecekapan 100%. Daripada kajian ini dapat disimpulkan bahawa Sepabeads207 menjerap etanol lebih baik dalam larutan statik berbanding turus dengan mengenakan keadaan terbaik.

7 TABLE OF CONTENT C H A PT ER T IT L E PA G E D ECLA RA TIO N D ED CA TIO N A C K N O W LED G EM EN TS ABSTRACT A B STR A K TABLE O F C O N TEN T LIST O F TABLES LIST O F FIG U R ES LIST O F SYM BOLS LIST O F A BBREVIATIONS LIST O F A PPEN D EC IES ii iii iv v vi vii x xi xiii xv xvi 1 IN TR O D U C TIO N Background o f the Study Problem Statement Objectives Scope 3 2 LITRA TU R E R EV IEW 2.1 Introduction The Behavior of Azeotropic Ethanol / W ater Various Types o f Distillation Processes Process o f Extractive Distillation Extractive Distillation by Salt Extractive Distillation with Liquid Solvent Extractive Distillation with the Combination o f Liquid Solvent and Solid Salt 18

8 2.4.4 Extractive Distillation with Ionic Liquid Pervaporation Technique Adsorption Technique Zeolite W ater Adsorption Ethanol Adsorption Concluding Remarks 30 3 M ETH O D O LO G Y 3.1 Introduction Chemicals and apparatus Chemicals Apparatus Preparation o f ethanol Solution Experimental Set-Up M ethodology Adsorbing Study Stripping Study Adsorption Performance o f Sepabeads Determination of Calibration Curve for Ethanol Concentration 41 4 RESULTS AND DISCUSSION 4.1 Introduction Parameters Affecting Adsorption Process Effect of Temperature on Adsorption Process Effect of ph on Adsorption Process Effect of Time on Adsorption Process Stripping Process Effect of Time on Stripping Process Effect of Temperature on Stripping Process Evaluation of Best Conditions for Adsorption and Desorption Processes Adsorbent Capacity Adsorbent Selectivity Efficiency o f Adsorbent 58

9 4.5 Comparison between the Results of Gas Chromatography and Refractom eter 58 5 CONCLU SIO N AND RECO M M EN D A TIO N 5.1 Conclusion Recommendation for Future W ork 62 R E FEREN C E S 63 A PPEN D ICES 67

10 LISTS OF TABLES TABLE NO. T IT L E PA G E 2.1 Properties o f Ethanol Summary o f the binary systems with different salts Examples of the liquid solvents commonly used in the extractive Distillation The influence o f various solid salt and liquid solvents on the relative volatility o f ethanol and water Comparison for techniques o f separation ethanol from water ethanol mixture Adsorbent Properties (Sepabeads207) Adsorbed ethanol concentration by applying best conditions Error analysis o f the results o f G.C and refractometer 60

11 LIST OF FIGURES FIG U R E NO. T IT L E PAGE 2.1 Ethanol (1) -W ater (2) Composition Curve VLE plot for ethanol (1)/ water (2) system showing liquid composition C2 produces and vapor composition C Ethanol-W ater hydrogen bonding Two column for extractive distillation process The process o f extractive distillation with salt Pressure pervaporation process Sweep gas pervaporation process Primary building units (PBUs) in zeolites and an example of linking Some examples o f secondary building units (SBUs) present in zeolites The methodology chart for adsorption and stripping processes Experimental Set-up Flow diagram of adsorption process Flow diagram of stripping process Calibration o f ethanol concentration using refractive index Effect o f tem perature on adsorbed ethanol Volum e o f adsorbed ethanol at varying tem perature Effect o f ph on ethanol adsorption The acidity o f ethanol solution affecting the linking between ethanol and water molecules Effect o f ph on ethanol volume Effect o f time on ethanol concentration Volum e o f ethanol adsorbed at different adsorption tim e 50

12 4.8 Effect of time on concentration of stripped ethanol in stripping process Effect of time on the stripped ethanol volume in stripping process Effect of temperature on the concentration of stripped ethanol in stripping process Effect o f tem perature on the volume of stripped ethanol in stripping process 54

13 LIST OF SYMBOLS M - Adsorbent capacity S - Adsorbent selectivity 0 - Efficiency o f adsorbent Al - Aluminum Co - Cobalt CO2 - Carbon Dioxide Ge - Germanium GE - Gibbs Energy H 2O - W ater HCl - Hydrochloric Acid Mg - Magnesium Mn - Manganese N 2 - Nitrogen N aa - Zeolite N ao H - Sodium Hydroxide nd - refractive index -N -H - Nitric Group N O x - Nitrogen Oxygen Compound O2 - Oxygen -O -H - Hydroxide Group P - Phosphor Pi - Pressure of component i ph - M agnitude o f acidity Psat - Saturated Pressure R - Gas Constant S - Solvent

14 Si-O-H - Silanol groups SOx - Sulfur Oxygen Compound T - Temperature X - Mole / Mass Fraction in Liquid Phase Xi - Mole Fraction of i Component in Liquid phase Y - Mole / Mass Fraction in Gas Phase Zn - Zinc

15 LIST OF ABBREVIATIONS ACN - Acetonitrile C2H5OH - Ethel alcohol ( Ethanol ) DMF - Dim ethethylformanide E10-10 percent ethanol and 90 percent gasoline E85-85 percent ethanol and 15 percent gasoline HPLC - High Performance Liquid Chromotography M TBE - Methyl t-butyl ether NM P - N-m ethyl-pyrrolidone PDMS - Polydimethylsiloxane PDMS - PS IPN polydimethysiloxane-polystyrene interpenetrating polymer netw ork PVA - Polyvinyl acetate SBUs - Secondary Building Units THF - Tetrahydrofuran VLE - Vapor Liquid Equilibrium

16 LIST OF APPENDECIES A PPEN D IX T IT L E PA GE A Data for refractometer 67 A.1 Data for standard ethanol/water solutions link between nd and Percent of ethanol for 1st batch 67 A.2 Data for standard ethanol/water solutions link between nd and percent of ethanol for 2nd batch. 68 B Data o f ethanol percent at various temperatures o f adsorption 69 B.1 Data o f ethanol concentration and volume at different temperature for adsorption process for 1st and 2nd batch 69 B.2 Data of average ethanol concentration and volume at different tem perature o f adsorption process 69 C Data o f ethanol percent at various adsorption times 70 C.1 Data o f ethanol concentration and volume at different time for adsorption process for 1st and 2nd batch 70 C.2 Data o f average ethanol concentration and volume at different tim e o f adsorption process 70 D Data of ethanol percent at various ph of feed solution 71 D.1 D ata of ethanol concentration and volume at different ph of feed for adsorption process for 1st and 2nd batch 71 D.2 D ata of average ethanol concentration and volume at different ph o f feed of adsorption process 71 E Data of ethanol percent at various stripping time 72 E.1 Data of ethanol concentration and volume at different time for stripping process for 1st and 2nd batch 72 E.2 Data o f average ethanol concentration and volume at different time of stripping Process 72 F Data of ethanol percent at various temperatures of stripping 73 F.1 D ata o f ethanol concentration and volume at different tem perature for stripping process for 1st and 2nd batch 73

17 F.2 Data o f average ethanol concentration and volume at different tem perature o f stripping process 73

18 C H A PT ER 1 IN TR O D U CTIO N 1.1 B ackground of the Study Fuel grade bioethanol production has gained interest globally because of its use as fuel oxygenate and as alternative fuel. Bioethanol is repeatedly being utilized as a fuel oxygenate instead of methyl t-butyl ether (MTBE) or fuel additive to increase the octane number. Fermentation process is the main way to produce bioethanol fuel from the sugar; although there are many ways to manufacture ethanol by the chemical process or as a by-product of some chemical processes (Vane, 2005). The main sources of bioethanol are sugar from crops including corn, maize and wheat crops. Recently, there is more research has been done to produce bioethanol from lignocellulosic biomass such as from oil palm biomass, woods and plant waste. Bioethanol or chemically called ethyl alcohol (C2H5OH) is a clear colorless liquid, low in toxicity, biodegradable, and makes little pollution to the environment if spilt (O'Brien and Craig, 1996). Burning of ethanol produces water and carbon dioxide. Bioethanol is applicable alternative fuel and virtually limitless potential for growth. The production of alternative fuel is due to the limitation of fossil fuel such as crude oil, hence the going towards more different sources of renewable o f energy.

19 Generally, ethanol is going to be one of alternative environmental friendly fuel friendly and harmless to the environment than gasoline. Using ethanol as a fuel for vehicles introduce benefit to minimize emissions of carbon dioxide and carbon monoxide, the same or lower emissions levels of hydrocarbon and oxides of nitrogen. For example E85 fuel is produced by blending of 85 percent ethanol and 15 percent gasoline, this blending decreases the consumption of fossil fuel and has lower percent of volatile components than pure gasoline, leading to the decrease of emissions occurred by evaporation. Low percentage of blending ethanol with gasoline, such as 90 percent gasoline and 10 percent ethanol (E10) leads to reduce emissions of carbon monoxide and improving the octane number for the fuel. Fuel of the vehicles becomes more flexible by using (E85). In United States, the use of E85 is growing due to the increase num ber o f fuel stations (ethanolrfa, 2013). 1.2 Problem Statem ent Mostly, the production of bioethanol involves pretreatment stage with acid or base solution, hydrolysis either with sulphuric acid, and fermentation with yeast broth. Usually, the end stream contained ethanol, and impurities. There are many techniques to separate ethanol from ethanol / water mixture such as distillation process, extractive distillation with Salt, solvent liquid or with ionic liquid, pervaporation process and adsorption process. It is critical to find the most suitable method to separate ethanol from the impurities that requires less energy, simple and low cost, yet, is efficient. The difficulty of separation of ethanol from water (broth of fermentation) is come from the generation of an azeotrope in the mixture at certain temperature. This azeotropic behavior appears because of presence of hydrogen bonds. Hydrogen bonds lead to interaction between molecules of ethanol and water. This interaction makes separation o f ethanol become difficult. The Azeotropic point appears at

20 composition of 95.6(wt) % for ethanol and the rest is water. Traditional technique like distillation consumes high energy. Hence, adsorption techniques will be studied as it is expected to give good separation at low cost, especially for low ethanol concentration in water and impurities stream. 1.3 O bjectives In general, this work is aimed to study the efficiency of the adsorption technique to achieve good purity of bioethanol production by manipulating the operating condition, such as time of adsorption, time of stripping, mass ratio ethanol/adsorbent (capacity of adsorbent), temperature and acidity of the feed. Following are the objectives o f this study. i) To study the effect of operating conditions on the efficiency of the adsorption technique to achieve good purity o f bioethanol. ii) iii) To evaluate the best operating conditions for adsorption of model bioethanol mixture. To evaluate the best operating conditions of stripping process, i.e., air tem perature and time. 1.4 Scope The simulated mixture of bioethanol has concentration 10wt%. Sepabeads207 was used in the adsorption and stripping processes. The operation parameters of adsorption such as time of adsorption (5-25 min.), temperature

21 (20-40 C) and acidity of the feed (4-7) were varied and evaluated the best conditions. The stripping process parameters were studied time (15-35 min.) and temperature (80-95 C). The yield of bioethanol was determined by direct volume measurement whereas the purity of bioethanol was analysed by gas chromatography and refractometer.

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