Inorganic Porous Material for Remediation of Texas Environment

Abstract

 In this experiment, we tested how much red dye zeolite and magnetized zeolite could absorb compared to charcoal. First, we had to synthesize two different types of zeolites, magnetized and unmagnetized, and create solid forms of each type. Once the solids were formed, we could grind up and use to absorb the red dye. We then established an experiment to calculate how much red dye zeolite, magnetized zeolite, and charcoal was left in solution. After analyzing, we can conclude that charcoal is the most effective inorganic porous material in absorbing red dye from water.

Introduction

 PAHs are formed by incomplete combustion and released into the environment through coal and gasoline, as well as organic substances such as wood and Tabaco. Humans encounter PAHs regularly, but an overexposure to these hydrocarbons can lead to serious health problems, which is why scientist are looking into ways to eradicate PAHs from the environment. A Zeolite is a crystalline structure that help break down large organic molecules into smaller molecules through a process called catalytic cracking¹. With this unique structure, it is hypothesized that inorganic porous materials such as zeolites and charcoal will absorb the PAHs and take them out of water. Resulting in an experiment that compares how well each of the porous materials can absorb red dye, which has a similar structure to PAH.

Materials and Methods

 The first step was to synthesize the non-magnetized Zeolite. Starting off, we put 50 mL of 3.0 NaOH solution into a 250 mL beaker along with a magnetic stir bar. Then, 3.73 g of sodium aluminate was added to the solution. The beaker was then placed over a hot/stir plate where it was heated and stirred until all solids were completely dissolved. The ring stand was setup with a thermometer that would be lowered into the solution, without touching the bottom of the beaker. While the solution was heating, 50mL of distilled water was boiled in a 150mL beaker, then 2.65 g of sodium silicate was added into the boiling water. The beaker was then placed on the extra hot plate and stirred by hand until the solids were completely dissolved. Each solution was brought to a boil, once both reached a boil, the sodium silicate was slowly poured into the sodium aluminate solution. For the next 60 minutes, the reaction was kept around 90^oC along with constant stirring to prevent any lumping materials to form. After 60 minutes, the hot plate was turned off and let cool for 5 min. Carefully, pour two equal parts of the cooled down solution into 2 centrifuge tubes, which were capped and labeled. The tubes were then placed into a centrifuge for 10 min at 5000 rpm. The liquid from the tubes were then poured out and all the solid was removed with a small spatula and placed on a petri dish to be dried.

 A similar procedure was followed to synthesize the magnetized Zeolite. The first step was to synthesize the non-magnetized Zeolite. Starting off, we put 50 mL of 3.0 NaOH solution into a 250 mL beaker along with a magnetic stir bar. Then, 3.73 g of sodium aluminate was added to the solution. The beaker was then placed over a hot/stir plate where it was heated and stirred until all solids were completely dissolved. The ring stand was setup with a thermometer that would be lowered into the solution, without touching the bottom of the beaker. While the solution was heating, 50mL of distilled water was boiled in a 150mL beaker, then 2.65 g of sodium silicate was added into the boiling water. The beaker was then placed on the extra hot plate and stirred by hand until the solids were completely dissolved. Each solution was brought to a boil, once both reached a boil, the sodium silicate was slowly poured into the sodium aluminate solution. For the next 60 minutes, the reaction was kept around 90^oC along with constant stirring to prevent any lumping materials to form. Next, .78 g of FeCl₃ and .39 g FeSO_{4 *} 7H₂O was added to the beaker. After 60 minutes, the hot plate was turned off and let cool for 5 min. Carefully, pour two equal parts of the cooled down solution into 2 centrifuge tubes, which were capped and labeled. The tubes were then placed into a centrifuge for 10 min at 5000 rpm. The liquid from the tubes were then poured out and all the solid was removed with a small spatula and placed on a petri dish to be dried.

 To formulate an absorbance vs. wavelength graph, 5 cuvettes were prepared. The first cuvette is a blank sample, filled with distilled water. The second cuvette was the undiluted sample and was filled with 0.05mM Procion Red MX-5B. The next 3 samples were prepared using the successive dilution method. Take 5mL of 0.05mM Procion Red with a volumetric pipet and place into a 10mL volumetric flask, the remainder of the flask should be filled up with distilled water to the etched line on the flask. The third cuvette was filled with 0.025mM Procion red solution. Take 5mL 0.025mM Procion Red with a volumetric pipet and place into a 10mL volumetric flask, the remainder of the flask should be filled up with distilled water to the etched line on the flask. The fourth cuvette was filled with 0.0125mM of Procion Red with a volumetric pipet and place into a 10mL volumetric flask, the remainder of the flask should be filled up with distilled water to the etched line on the flask. Lastly, the fifth cuvette was filled with 0.00625 mM Procion Red solution.

 To compare the three porous materials, three cuvettes of charcoal, magnetized, and un-magnetized zeolite were prepared. First weigh out 0.1163 g of charcoal, 0.1117 g magnetized, and 0.1186 g unmagnetized zeolite then place into 3 separate mortars. Add 1mL of water to the mortar and crush well with the pestle thoroughly. Set up filter using a filter paper and funnel over a 10 mL volumetric flask. Rinse the mortar and pestle with the Procion Red and then place components onto the filter paper. If the solution is not clear after the first filtration, filter the solution a second time. Fill the remainder of the flask with the Procion red to the etched mark of the flask. Cap the flasks and gently mix and pour into three cuvettes.

 Now that all eight cuvettes have been prepared, set up spectrophotometer to find the absorbance spectrum, calibration curve, and test the absorbance of each solution. When setting up the spectrophotometer, first calibrate using the blank sample. Once calibrated, place the undiluted cuvette into the slot. Press START which will display the full absorbance spectrum and from that figure out where the λ max is at. The λ max and absorbance was 510.8 nm and 0.6980 found from the undiluted solution. To create a calibration curve, the settings had to be changed to absorbance vs. concentration in the spectrometer icon, and the λ max was selected.

 After collecting the data, the molar concentration was entered starting with the .00005 M. The following step requires the three dilution samples to be placed and ran through the spectrophotometer. Starting with the .000025 M sample, then .0000125 M sample, and the final dilution sample being .00000625 M. Each sample was read and added to the calibration curve. To figure out the absorbance of each porous material, each sample was placed into the spectrophotometer and was recorded and collected at λ max as well as at 750nm.

Results and Discussion

 After collecting the absorbance spectrum found from the undiluted solution, the λ max was found to be 510.8 nm. To find the concentration of red dye that was left in each solution, the application of Beer’s Law was required and used for each of the porous solutions, but first we found the molar absorptivity constant from the slope of the calibration curve.

For Magnetized Zeolite, the concentration of red dye is: C = (1.352)/ (1.0) *(14861)

C = 0.000091 M

For Non- Magnetized Zeolite, the concentration of red dye is: C = (2.313)/ (1.0) *(14861)

C = .000156 M

For Charcoal, the concentration of red dye is: C = (.316)/ (1.0) *(14861)

C = .0000213 M

Based on these calculations of the concentration of red dye still in the solution, we can say that the solution with the smallest concentration was the most effective at removing the red dye from the solution. So, from this experiment, the results led to Charcoal being the most effective Porous material.

One source of error during the experiment was the concentration of both the Magnetized and Unmagnetized Zeolite. When filter both zeolites through the filter paper and funnel, some solids may have gone through either from a hole in the filter paper, or the sides of the beaker. This resulted in a cloudy solution, which caused for a redo in the experiment. When going through the same process once again, the results ended up the same, a cloudy solution for both zeolites formed. Already losing time, we used those solutions instead of a clear solution, like our charcoal solution.

An important parameter that is tested is the effectiveness of the porous materials in absorbing the PAHs (red dye). Before choosing any material over the other, such as magnetized zeolite over charcoal, its important to test each material and view the results, then choose from what is observed. Another parameter to consider would be how effective is the process to make zeolite over charcoal would have on the environment. Such as, if there was a large amount of excess zeolite purifying water, the excess amount could end up harming the surroundings than if charcoal was being used. Even if the water is purified and the zeolite did its job successfully, it may also negatively impact the environment during the process. It would probably be safer just to use charcoal in this case. A third parameter would be the cost of the porous material. Though one material may be more successful at absorbing the PAHs, let’s say zeolite, it may be more expensive to produce such material instead of charcoal. Through this prospective, charcoal would be more cost effective than zeolite.

Looking closely at both structures, the PAH, Benzopyrene (a.) and Procion Red MX-5B (b.) have similar features, both are thin and flat. Because of this, they can fit through the structures found in Zeolites and Charcoal, making Procion Red a suitable substitute for a PAH to test the removal properties of each porous material.

Conclusion

In this experiment we designed a test to figure the properties of magnetized/ unmagnetized zeolite compared to charcoal. We used Procion Red MX-5B as a substitute for a PAH to test how well each porous material effectively absorbed the pollution. Through this experiment and with the help of Beer’s Law we can calculate the concentration of Procion Red that was left over after each material had time to absorb the red dye. After calculations, we concluded that charcoal was the most effective porous material for removing PAHs because it left the least amount of red dye compared to both zeolites tested.

References

• ¹ Peter B. Leavens “Zeolites” Advameg Inc.,2018, http://www.chemistryexplained.com/Va-Z/Zeolites.html
• *Author of Inorganic Porous Material for Remediation of Texas Environment