Passage VI
Biosorption is a process that uses certain biological materials (biomass) to remove metal ions from a solution. Three experiments were done to study the removal of the chromium ion Cr6+ from aqueous solutions using a biomass composed of crushed shells of the fruit Litchi chinensis. In each trial in each experiment, the following steps were performed:
1. In a flask, 1.0 g of fresh biomass was added to 100 mL of an aqueous solution having a particular pH and Cr6+ concentration.
2. The flask was capped, and the contents were shaken for a particular time at a particular temperature.
3. Periodically, shaking was stopped so that a 0.01 mL sample could be removed from the flask. This sample was analyzed to determine the percentage of Cr6+ remaining in the solution.
Experiment 1
In each of Trials 1-4, an aqueous solution with an initial concentration of 100 mg/L was tested at a temperature of 30°C. The pH was varied from trial to trial. The results are shown in Figure 1.
Experiment 2
In each of Trials 5-7, an aqueous solution with an initial Cr6+ concentration of 100 mg/L was tested at a pH of 1.0. The temperature was varied from trial to trial. The results are shown in Figure 2.
Experiment 3
In each of Trials 8-11, an aqueous solution at a pH of 1.0 was tested at a temperature of 30°C. The initial Cr6+ concentration was varied from trial to trial. The results are shown in Figure 3.
35. Based on Figure 1, if a sample from Trial 3 had been analyzed at 95 min, the percentage of Cr6+ remaining in the solution would most likely have been:
Your Answer is
Correct Answer is A
Explanation
The abscissa of figure 1 is only drawn up to 90 minutes, so the value needs to be estimated. Looking at the line of trail 3, at 95 minutes, the ordinate should be slightly less than 5% of that at 90 minutes, and option A meets