Optimizing Cao Through Ethanol/Water Hydration for Carbon Dioxide Capture Essay

By Azrul Bin Alias Progress report submitted in partial fulfillment of the requirements for the Bachelor of Engineering (Hons) (Chemical Engineering) JULY 2009 Universiti Teknologi PETRONAS Bandar Seri Iskandar 31750 Tronoh Perak Darul Ridzuan ABSTRACT The objective of this project is to optimize the preparation of modified Calcium Oxide (CaO) to capture CO2 by carbonation through hydration of ethanol/water. The carbonation reaction is the basis for CO2 capture systems.

However CaO as regenerable CO2 sorbents in industrial processes is limited by the rapid decay of the carbonation conversion with the number of cycle carbonation/ calcination. Therefore Calcium based sorbents have attracted renewed attention as possible sorbents for cyclic calcination/carbonation processes due to their potential for regeneration and effective technique for capturing CO2 from combustion processes. The carbonation conversion for CaO modified with ethanol/water solution is greater than for CaO hydrated with distilled water and is much higher than that for calcined limestone. Li et all). This work covers and presents a multi experimental test of preparing the modified CaO through hydration of water/ethanol by manipulate various parameter combination. The experiments were conducted using a modified furnace to permit the flow of CO2 for carbonation process and calcium oxide. Then, the carbonation conversion is calculated which signify the effectiveness of CO2 capture and the optimum parameter to produce the highest carbonation conversion is identified based on approach of Taguchi Method , the signal-to-noise (S/N) ratio and the analysis of variance (ANOVA).

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Through this study the optimal parameter to prepare modified CaO through ethanol/water hydration can be obtained. TABLE OF CONTENT ABSTRACT CHAPTER 1 INTRODUCTION 1. 1Background of Study 1. 2Problem Statement 1. 3Objectives & Scope of Study CHAPTER 2LITERATURE REVIEW 2. 1Carbonation/calcinations process 2. 2Temperature 2. 3Pressure 2. 4 Particle Size 2. 5Carbonation Duration CHAPTER 3METHODOLOGY 3. 1 Research methodology 3. 2Project Activities 3. 2. 1 Preparation of modified CaO through ethanol/water hydration 3. . 2 Carbonation of modified CaO. 3. 3Tool 3. 3. 1 Apparatus 3. 3. 2 Chemical Reagent 3. 4 Project Flow Chart (Gantt Chart) CHAPTER 4RESULT & DISCUSSION 4. 1 Analysis of the S/N ratio 4. 2 Analysis of variance (ANOVA) 4. 3 Confirmation experiment CHAPTER 5 CONCLUSION REFERENCES CHAPTER 1 INTRODUCTION 1. Project Background It is now generally accepted that CO2 is one of the major greenhouse gases that is directly influencing the global climate changes .

The efficient CO2 capture technologies are desired to significantly reduce CO2 emissions from large stationary source fossil fuel-fired power stations. Therefore, the production of energy and fuel from biomass is receiving considerable interest particularly due to concerns regarding energy security and the need to reduce greenhouse gas emission. A highly promising way to exploit biomass resource involves converting biomass to hydrogen rich gas which could be utilized as a replacement energy carrier for fossil fuels in the transport, industrial, commercial and residential sectors.

In order to maximize the output of hydrogen, the gasification can be coupled with in situ CO2 capture using CaO. CaO-based sorbents, in particular lime (CaO) produced from limestone, have been intensively investigated as sorbents for CO2 capture during the last several years and found that the modified CaO which is carbonation conversion for CaO modified with ethanol/water solution is greater than for CaO hydrated with distilled water and is much higher than that for calcined limestone and it is proved as a new and promising type of regenerable CO2 sorbent for industrial applications. . Problem Statement CO2 capture system based on the carbonation/calcination loop, still in its infancy, has gained rapid interest due to promising CO2 capture efficiency, low sorbent cost. Nevertheless, the use of calcium oxide (CaO) as regenerable CO2 sorbents is bottlenecked by the fast decomposition of the carbonation conversion with the number of cycles carbonation/calcination.. Therefore, the efforts to maximize CO2 capture by modified of CaO sorbent become essential.

The extend study on preparation of modified calcium oxide (CaO) sorbent will be carried out to come out with best conditions that can maximize CO2 while preserve the CaO sorbent throughout the carbonation process. 3. Objectives and Scope of Study The objective of this project is to: • To optimize the CaO carbonation conversion for CO2 capture. • To propose optimum conditions of variables to prepare modified CaO through ethanol/water. To study the activity of CaO in term of efficiency to capture CO2 throughout carbonation In order to achieve the objectives, research on journals need to be carried out by collecting all technical data regarding regenerable CaO sorbent for CO2 capture CHAPTER 2 LITERATURE REVIEW 2. 1 Process The integration of continous Ca-looping scheme, exploiting the reversible reaction between CaO and CO2 offer potential for reducing cost of CO2 capture in future clean energy system (Abandes et al. , 2007). The exothermic carbonation reaction is given in Equation 1 CaO (s) + CO2 (g)>CaCO3(s) H = ? 78 kJ/mol (1) Once CaO has reached its ultimate conversion of CaCO3, it can thermally be regenerated to CaO and CO2 by heating CaCO3 beyond the calcination temperature. The endothermic calcination reaction is given below: CaCO3 (s ) > CaO (s) + CO2 (g) H = + 178 kJ/mol (2) The carbonation calcination reaction (CCR) scheme, based on reactions 1 and 2, alternates carbonations and calcinations over multiple cycles to capture CO2 from flue gases. From the research done by Sivalingam et al, there are number of advantages in this CCR based CO2 capture with CaCO3 a sorbent material. 2. 2 Temperature

Both carbonation and calcinations reaction take place at temperature, essentially above 600oC enabling the effective recovery of calcinations energy in carbonator (Sivalingam et al,2008). However, in term of sorbent capacity, Vasilije M and E. J Anthony found that the influence of increasing the temperature in the range 650-850oC has a negative effect on the sorbent activity which is faster sorbent activity loss with increasing numbers of calcinations /carbonation cycles. This is because both ion migration in the sorbent crystal structure and sintering are strongly influenced by temperature.

Furthermore, sintering result in decreased sorbent surface area and reduced conversion in reactions, with formation of a solid layer on the surface of the solid reactant (CaO). In the case of carbonation, the product layer (CaCO3) also reduces contact between gaseous CO2 and solid CaO, and it is known that the maximum conversion depend on the sorbent surface area. Solid state diffusion through the product layer is also enhanced by temperature, which should lead to higher conversions with increased temperature; however, samples cycled at higher temperatures are more sintered and, hence, less active, as is demonstrated in Figure 1.

In other word, the influence of temperature on sorbent sintering is masked by enhanced carbonation at higher temperature. Therefore, the proposed temperature is within range 750oC to 850oC for carbonation is unfavorable as its will faster loss of sorbent activity. [pic] Figure 1: Influence of temperature on the sorbent activity decay of Kelly Rock limestone (KR01) with a particle size of 75–150 ? m: (a) 10 cycles (90 min calcination +30 min carbonation) at different temperatures; (b) continued runs, 11th carbonation at the same temperature (750 °C). Vasilije and Edward, 2008) According to thermodynamics relationship of equilibrium partial pressure of CO2 calculated by using HSC CHEMISTRY 5. 0 software from Outokumpu Research Oy, Finland as a function of calcinations temperature of CaO/CaCO3 system, the plot show that at a given temperature, a partial pressure of CO2 (Pco2) lower than equilibrium pressure (Peq) favors calcination and vise versa. For example, Peq at 792 oC, calcinations would be favored if the actual partial pressure of CO2 were lower than 0. 2 bar. On the other hand calcinations at a Pco2 of 0. bar can be induced by increasing the temperature beyond 792oC. [pic] Figure 2: Equilibrium partial pressure of CO2 plotted against the temperature as obtained by thermodynamic calculations (Sivalingam et al, 2008) 2. 3 Pressure The carbonation/calcination of the CaO/CaCO3 system does not require pressurized conditions unlike the other sorption processes that need high pressures and/or low temperatures to enhance the sorption efficiency. The CO2 absorption by calcium oxide is strongly dependent on the partial pressure of CO2 in the product stream at the specified gasification temperature.

Determination of equilibrium partial pressure of CO2 resulting from the decomposition of CaCO3 was attempted b several investigators many decades ago (Baker,1962; Currant et al. ,1966; Hill and Winter, 1956; Johnson,1910;Smyth and Adam,1923) and reproduced by N. H Florin and A. T Harris. The experimental data from all studies are close agreement with the predicted equilibrium partial pressure derived using thermo dynamical data according to Equation 3 is equivalent to the calculation of the equilibrium constant (Ka) (Sandler,1999) [pic] (3)

When the gasification temperature is less than the equilibrium temperature corresponding to the CO2 partial pressure, CO2 is absorbed and the sorbent gets converted to CaCO3; above this temperature CaCO3 desorbs to produce the original CaO as shown in Figure. 3. [pic] Figure 3: Equilibrium CO2 partial pressure as function of temperature. 2. 4 Particle Size. The literature shows that there are no significant effects of particle size when comparing maximum carbonation conversions under typical conditions, and only under extreme conditions can particle size be an important parameter. Vasilije et al,2008). Particle size influences only the rate of carbonation (the shift between the fast and slow reaction stages is more pronounced in the case of smaller particles), but with increasing cycle number this effect disappears; that is, larger pores are formed, enhancing CO2 diffusion through the particle porous structure. Insensitivity of the maximum carbonation conversions to particle size is a direct consequence of the fact that carbonation inside the particle is typically uniform; that is, there is no radial conversion profile.

However, in some cases, it was noticed that there was an unexpected particle size influence: the conversion of smaller particles was lower as shown in Figure 6. Edward J Anthony et al believes the decreased carbonation conversions obtained with smaller particles may be the result of parameters other than particle size. In term of sorbent activity decay, it is significantly slower for the powdered samples (less than 50[pic] ) as shown in Figure 7. This also confirms activation of the sorbent by grinding. (Sivalingam et al, 2006).

Various particle size has been used during previous work such as particle size from 125 – 180[pic](Sivalingam et al, 2006), particle size from 100 – 1000 [pic] (Grasa and Abandes,2006), particle size from 100 to 800[pic] (Abandes, 2002), particle size at 500 [pic] (Shimizu et al,99) and particle size below 10 [pic] (Silaban et at ,95). [pic] Figure 4: Influence of the sorbent particle size on the sorbent activity decay of KR limestone: (a, b) 10 cycles at 800 °C, 15 min calcinations (Vasilije and Edward,2008) + 15 min carbonation; (c) continued runs, 11th cycle at 750 °C for 30 min calcination +30 min carbonation. . (Vasilije Manovic and Edward J Anthony, 2008) [pic] Figure 5: Influence of the sorbent particle size on the sorbent activity decay of the CD, the GR, and the HV limestones, with a particle size of 0. 250–0. 425 mm, 10 cycles at 800 °C, and 15 min calcination + 15 min carbonation. ). (Vasilije and Edward, 2008) 2. 5 Carbonation Duration Carbonation duration is also important parameter to be identified to optimize the carbonation/calcinations cycle. In term of sorbent activity, the longer arbonation period led to a faster loss of sorbent activity. The result of the research done Vasilije et al where the calcination is fixed for 90 min and three carbonation times (10, 30, and 240 min) were chosen, and the results are shown in the Figure 8. [pic] Figure 6: Influence of carbonation duration on the sorbent activity decay of KR01 limestone: (a) 10 cycles, 90 min calcination; (b) continuedruns, 11th cycle at 750 °C for 30 min calcination +30 min carbonation.

Designation: for example, 90D-30C-750 °C indicates a 90 min calcination (decomposition, D), a 30 min carbonation (C), and a temperature of 750 °C. ). (Vasilije and Edward, 2008) For the purpose to observe the pattern of conversion of carbonation (%) with respect to carbonation period, the period from 10 to 15 minute is acceptable because the longer carbonation period would not give significant changes in carbonation conversion. [pic]. Figure 7: Conversion (X) in the first carbonation reaction cycle. (Florin and Harris, 2008) CHAPTER 3

METHODOLOGY 3. 1 Taguchi Method Design of Experiment The steps involved in the Taguchi Method are as follows: 1. The process objective, or more specifically, a target value for a performance measure of the process is defined which are adsorption capacity and adsorbent conversion. 2. The design parameters affecting the process are determined. Parameters are variables within the process that affect the performance measure that can be easily controlled. In this case the parameters are A: Solution volume B: Ethanol concentration C: Mixing time

D: Drying temp E: Drying time 3. The number of levels that the parameters should be varied at must be specified. In this experiment level of the parameters is decided which is 3. Then, increasing the number of levels to vary a parameter at increases the number of experiments to be conducted. 4. All the factors and relation that interest to study are listed. In this experiment the relation are A, B,C, B xC, D, E, DxE 5. Orthogonal arrays for the parameter design indicating the number of and conditions for each experiment are created.

The selection of orthogonal arrays is based on the number of parameters, the levels of variation for each parameter and degree of freedom and will be expounded below. In this experiment L18 will be used. 6. The experiments indicated in the completed array are conducted to collect data on the effect on the performance measure. 5. Data analysis is completed via main effect and ANOVA to determine the effect of the different parameters on the performance measure. For this experiment, weight difference will represent as carbonation conversion. |Factor |Level | | | |1 |2 |3 | |A |Solution volume (mL) |150 |300 |450 | |B |Ethanol concentration (%) |50% |70% |90% | |C |Mixing time (hours) |1 |2 |3 | |D |Drying temperature (oC) |80 |100 |120 | |E |Drying time (hours) |1 |1. 5 |2 | Table 1: Factor and level parameters of the experiment |Exp. No |Factor | | |Solution Volume (A) |Ethanol Conc. (B) |Mixing time (C) |Drying Temp. (D) |Dryingtime (E) | |1 |1 |1 |1 |1 |1 | |2 |1 |2 |2 |2 2 | |3 |1 |3 |3 |3 |3 | |4 |2 |1 |1 |2 |2 | |5 |2 |2 |2 |3 |3 | |6 |2 |3 |3 |1 |1 | |7 |3 |1 |2 |1 |3 | |8 |3 |2 |3 |2 |1 | |9 |3 |3 |1 |3 |2 | |10 |1 |1 |3 |3 |2 | |11 |1 |2 |1 |1 |3 | |12 |1 |3 |2 |2 |1 | |13 |2 |1 |2 |3 |1 | |14 |2 |2 |3 |1 |2 | |15 |2 |3 |1 |2 |3 | |16 |3 |1 |3 |2 |3 | |17 |3 |2 |1 |3 |1 | |18 |3 |3 |2 |1 |2 | Table 2:L18 Orthogonal array By adjusting experimental combinations and analyzing experimental result, this work leads to the optimum preparation of modified CaO that enable to absorb high CO2 as well as high level of CaO perseverance throughout the carbonation process. 3. Project Activities There are three parts of experiments are going to conduct in order to complete the project purpose: 1. Preparation of modified CaO through ethanol/water hydration. 2. Carbonation of modified CaO. 3. Confirmation of optimum parameters to yield modified CaO 3. 2. 1 Preparation of modified CaO through ethanol/water hydration For preparing modified CaO through hydration of ethanol/water, the procedures are explained below by using Trial 1 as an example. Refer L18 Table 3. 2. 2 Carbonation of CaO/EtOH. H2O The modified CaO is then proceeded to undergo carbonation. The procedures are explained as below. 3. 3 Tools Required

The laboratory apparatus and chemical reagents required to accomplish the objective of the experiment which is to optimize the Calcium Oxide for CO2 adsorption through ethanol/water are as following; 1. Apparatus 1. Magnetic stirrer 2. Magnetic bar 3. Furnace 4. Oven 5. 500 mL beaker 6. Spatula 7. Tube furnace 2. Chemical Reagents 1. Absolute ethanol 2. Distilled water 3. Calcium oxide 4. Project Schedule [pic] Table 3: Gantt chart CHAPTER 4 RESULT AND DISCUSSION 1. Carbonation Conversion Calculation The example calculation extracted from experiment 1 is shown as below. Sample boat mass = 113. 2166 gram Initial CaO modified mass = 2. 0006 gram

Initial CaO modified and Sample boat mass = 115. 2172 gram Final CaO modified and Sample boat mass = 115. 2390 gram Final CaO modified mass = 2. 0224 gram Conversion = Mole Reacted Total no of moles Mole Reacted, CO2 = 0. 0218 gram 44. 0095 g/mole = 0. 000495 moles Total no of mole,CaO = 2. 0006 gram 56. 078 g/mole = 0. 03567 mole Conversion = 0. 000495 mole X 100 0. 03567 moles = 1. 38 % In this experiment CO2 is supply in excess. Higher carbonation conversion means more CO2 being adsorbed. 2. Analysis of the S/N ratio The Taguchi method employs a generic signal-to-noise (S/N) ratio to quantify the present variation.

In this experiment the value of carbonation conversion (X) is preferably to be in big number. Therefore, “higher is better”(HB) is chosen. The S/N ratios were calculated using the following equations:- [pic] (1) [pic](2) Where ? denotes the observed value which is the calculated value of the S/N ratio (unit: %), y n represents the observed value and n is the repeated number. Table below list the experimental result of carbonation conversion X to be obtained and the corresponding signal-noise ratios (S/N) using Equation 1 and 2. The mean S/N ratio for each level of the CaO/EtOH. H2O parameter is summarized and called the S/N response table for Carbonation Conversion and illustrated as in the Table below. |Factor |Level | | | |1 |2 |3 | |A |Solution volume (mL) |150 |300 |450 | |B |Ethanol concentration (%) | 50% | 70% | 90% | |C |Mixing time (hours) |1 |2 |3 | |D |Drying temperature (oC) |80 |100 |120 | |E |Drying time (hours) |1 |1. 5 |2 | Table 4: Setting of factors and levels in the experiment |Experiment |Control Factors |Carbonation Conversion (%) |S/N | |No. |A | |  |A |B |C |D |E | |1 |-16. 09 |-17. 35 |-17. 99 |-17. 67 |-18. 04 | |2 |-19. 04 |-18. 23 |-18. 28 |-18. 98 |-18. 27 | |3 |-20. 05 |-19. 1 |-18. 91 |-18. 53 |-18. 88 | |Level Effect |3. 95 |2. 26 |0. 92 |0. 85 |0. 83 | Table 6: S/N response table for carbonation conversion 4. 2 Analysis of variance (ANOVA) The purpose of the ANOVA is to investigate the design parameters that significantly affect the quality characteristic. The total sum of square SST from the S/N ratio ? can be calculated as: [pic] (3) Where n is the number of experiments in the orthogonal array and ? i is the mean S/N ratio for the i th experiment. The sum of squares from the tested parameter SSP can be calculated as: [pic](4)

Where p represents one of the tested parameters, j the level number of this parameter p, t the repetition of each level of the parameter p, S? j the sum of the S/N ratio involving this parameter p and level j. The sum of squares from error parameters, SSe is: [pic] (5) The total degrees of freedom is DT = m-1, where the degrees of freedom of the tested parameter DP = t-1. The variance of the parameter tested is VP=SSP/DP. Then, the F-value for each design parameter is simply the ratio of the mean-of-squares deviations to the mean of the squared error (FP=VP/Ve). The corrected sum of squares S P* can be calculated as: [pic] (6) The percentage contribution ? can be calculated as: pic] (7) The data will be gathered in the Table and Graph as illustrated as below; Table 7: The ANOVA table for carbonation conversion |Factor |Carbonation Conversion | |  |SS |DOF |Var |F ratio | ? (%) | |A |50. 627 |2 |25. 313 |115. 847 |57. 816 | |B |15. 610 |2 |7. 805 |35. 720 |17. 479 | |C |2. 685 |2 |1. 343 |6. 145 |2. 590 | |D |5. 62 |2 |2. 631 |12. 042 |5. 559 | |E |3. 228 |2 |1. 614 |7. 387 |3. 215 | |Error |9. 396 |43 |0. 219 | |13. 341 | |Total |86. 809 |53 |  |  |100. 000 | Note: A = Solution volume (mL) B = Ethanol concentration (%) C = Mixing time (hours) D = Drying temperature (oC) E = Drying time (hours) • = Contribution Figure 8: S/N graph for solution volume Figure 9: S/N graph for ethanol concentration Figure 10: S/N graph for mixing time Figure 10: S/N graph for drying time

Figure 10: S/N graph for drying temperature 4. 3 Confirmation experiment Once the optimal level of the design parameters has been selected, the final step is to predict and verify the improvement of the quality characteristic using the optimal level of the design parameters. The estimated S/N ratio Ypredicted using the optimal level of the design parameters can be calculated as:- [pic] [pic] = total mean S/N ratio = mean S/N ratio at the optimal level = is the number of the main design parameter that affect the quality characteristic. The measuring data and the actual S/N ratio of confirmation experiments will be listed in as Table below.   |Control Factors |S/N(dB) |Confirmation experiment | |A |B |C |D |E |prediction |Measuring data |Mean Value |S/N (dB) | |Carbonation Conversion | | | | | | | | | | | | | | | | | | | | | |  |  |  |  |  |  |  |  |  |  | |Table 8: The table for confirmation experiment of the carbonation conversion. CONCLUSION This project is discussing the optimization of the parameters for modifying CaO through ethanol/water hydration by using orthogonal arrays in the design of experimental method proposed by Taguchi to conduct the multiple factor experiment. This study discusses five modified CaO parameters including, ethanol concentration, and solution volume, drying temperature, drying time and mixing time.

The optimal parameters will be identified upon the completion of the entire experiment and the findings of the experiment possess great potential for future references. REFERENCES [1] N. H. Florin and A. T. Harris, “Enhanced H2 production from biomass coupled with CO2 capture using CaO”, University of Sydney, 2006 [2] N. H. Florin and A. T. Harris, “Reactivity of CaO derived from nano-sized CaCO3 particles through multipleCO2 capture-and-release cycles”, University of Sydney, 2006 [3] J. S. Hoffman and H. W. Pennline, “Study of Regenerable Sorbent for CO2 Capture”, U. S Department of Energy, 2000 [4] V. Manovic and E. J Anthonty, “Parametric Study on the CO2 Capture Capacity of CaO-Based Sorbents in Looping Cycles”, CANMET Energy Technology Centre-Ottawa, 2008 [5] S.

Sivalingam, “Cyclic Carbonation Calcination Studies of Limestone and Dolomite for CO2 Separation From Combustion Flue Gases”, International Gas Turbine Institute of ASME, 2008 [6] A. Bosoaga and J. Oakey, “CO2 capture using lime as sorbent in a carbonation/calcinations cycle”, Cranfield University, 2008 [7] J. C Abandes, “The maximum capture efficiency of CO2 using a carbonation/calcinations cycle of CaO/CaCO3”, Department of Energy and Environment (CSIC), 2002 [8] G. J Tzou, D. Y. Chen and C. Y. Hsu “Application of Taguchi method in the optimization of cutting parameters for turning operation”, Hwa Hsia of Technology Taiwan, 2005 [10] Luis M. RomeoYolanda Lara, Pilar Lisbona and Jesus M.

Escosa, “Optimizing make-up flow in a CO2 capture system using CaO ”, Universidad de Zaragoza, 2008 [11] M. Sarahintu, M. H. Lee and H. Mohamed “Determining the Effect of Scenario Metrics on the Performance of Dynamic Source Routing using Taguchi Method”, Universiti Teknologi Malaysia, 2007 [12] B. M. Gopalasamy, B. Mondal and S. Ghosh “Taguchi method and ANOVA: An approach for process parameters optimization of hard machining while machining hardened steel”, National Institutes of Tech. , Durgapur, 2009[pic] ———————– Repeat the experiment for Trial 2 till Trial 18 by following the assigned parameters as shown in Table L18. Take out the CaO/EtOH. H2O in the sample boat from the tube furnace [pic][pic] Measure the final weight Measure the CaO/EtOH. H2O after being heat up in the furnace and find the mass difference. Record the data and analysis via S/N analysis and ANOVA Put the solution into the oven • Temperature: 80oC • Duration:1 hour Put 2 g of CaO/EtOH. H2O powder into sample boat in the tube furnace. • Particle size of CaO : less than 0. 125 mm Set the automation of tube furnace configuration Stage 1 • Temperature : 650o C • Heating rate : 15°C/min During this heating period, purge gas valve is open to allow gas flow into the tube furnace • Duration : 5minutes • Pressure : 2 bar Flow rate of N2 : 0. 2 l/min Stage 2 • Temperature : 650o C • Duration : 30 minutes When the temperature reaches at 650o C, the CO2 valve is open into tube furnace. • Flow rate of N2 : 0. 7 l/min • Flow rate of CO2 : 0. 3 l/min Stage 3 • Temperature : 100o C The temperature is set to cool down until 0o C. Once the temperature start to drop from 650o C then closed CO2 flow control valve. The nitrogen is keep flowing as below; • Flow rate of N2 : 0. 2 l/min • Duration : 30 minutes Stage 4 Nitrogen flow control valve is closed. The tube furnace is let to cool down to the temperature 30oC for 1 hour.

Then, shut down the tube furnace switch. Measure the initial weight • Measure 2 gram of modified CaO by using delicate electronic balance. Repeat the experiment for Trial 2 till Trial 18 by following the assigned parameters as shown in Table L18. The modified CaO is stored in sample holder. Put the solution on the stir plate and filter the solution • Duration :1 hour [pic] Put 25 g of CaO powder into the 250 ml of 50 % ethanol solution. Prepare 150 ml of 50 % ethanol concentration. • Measure 75 ml of absolute ethanol and 75 ml of water by using cyclinder. • Mix volume of 75 ml ethanol and 75 ml water in a 500 ml beaker. [pic] Filter the solution [pic] [pic] [pic] [pic]


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