Calibration Curve for Procion Red Dye at = 538 nm Figure 1: λmax According to Beer’s Law, A = For this lab, A is absorbance, is molar absorptivity in units Ɛbc. Ɛ mM-1·cm-1, b is the path length, and c is concentration in mM. From the graph, A = 14.893c, so the slope 14.893 = bƐ. Since b = 1 cm, = 14.893 mM-1·cm-1 or 14893 M-1·cm-1. After the charcoal and Ɛ clay were added to remove the dye, the % transmittance of each filtered solution was measured and recorded from the spectrophotometer into Chart 2. The remaining dye concentration was then calculated in Chart 3. Charcoal and Clay Transmittance and Absorbance Results Chart 2: Determining Concentration of Dye Remaining Chart 3: Determining Moles of Dye Removed Per Gram of Substance Chart 4: According to the results, charcoal removed more dye as seen by the higher % transmittance and lower absorbance yielded from its filtered solution. Decreased absorbance means less dye was in the solution to absorb light so more light was transmitted. Using the calibration curve equation, it was found that the filtered charcoal solution had a lower concentration of dye remaining than the filtered magnetic clay solution. Finally, in Chart 4, by analyzing the moles remaining by using molarity times concentration to find the initial and final moles of dye, the amount of moles removed per gram of substance was found. Charcoal is more effective because it removed 6.7 x 10-6 moles dye removed /g charcoal which is greater than 1.1 x 10-6 moles dye removed / g clay. To compare the usefulness of the magnetic clay to the charcoal, one parameter is higher effective absorbance, which in the lab was determined as charcoal. A second parameter is the availability and cost of each. Since the US is the largest producer of Bentonite clay, it is widely available and relatively cheap. A third parameter important to industries is the ability to filter one substance over the other. Bentonite clay is a very fine powder and thus difficult to filter. Making the clay magnetic to more easily remove it
Figure 1: Calibration Curve for Procion Red Dye at λmax = 538 nm According to Beer’s Law, A = Ɛbc. For this lab, A is absorbance, Ɛ is molar absorptivity in units mM-1·cm-1, b is the path length, and c is concentration in mM. From the graph, A = 14.893c, so the slope 14.893 = bƐ. Since b = 1 cm, Ɛ = 14.893 mM-1·cm-1 or 14893 M-1·cm-1. After the charcoal and clay were added to remove the dye, the % transmittance of each filtered solution was measured and recorded from the spectrophotometer into Chart 2. The remaining dye concentration was then calculated in Chart 3. Chart 2: Charcoal and Clay Transmittance and Absorbance Results Chart 3: Determining Concentration of Dye Remaining Chart 4: Determining Moles of Dye Removed Per Gram of Substance According to the results, charcoal removed more dye as seen by the higher % transmittance and lower absorbance yielded from its filtered solution. Decreased absorbance means less dye was in the solution to absorb light so more light was transmitted. Using the calibration curve equation, it was found that the filtered charcoal solution had a lower concentration of dye remaining than the filtered magnetic clay solution. Finally, in Chart 4, by analyzing the moles remaining by using molarity times concentration to find the initial and final moles of dye, the amount of moles removed per gram of substance was found. Charcoal is more effective because it removed 6.7 x 10-6 moles dye removed /g charcoal which is greater than 1.1 x 10-6 moles dye removed / g clay. To compare the usefulness of the magnetic clay to the charcoal, one parameter is higher effective absorbance, which in the lab was determined as charcoal. A second parameter is the availability and cost of each. Since the US is the largest producer of Bentonite clay, it is widely available and relatively cheap. A third parameter important to industries is the ability to filter one substance over the other. Bentonite clay is a very fine powder and thus difficult to filter. Making the clay magnetic to more easily remove it