The effect of extrusion conditions, including feed rate (2.52-6.84 kg/h), feed moisture content (13-19% wet basis), screw speed (150-250 rpm), and extrusion temperature (150-230°C) on structural properties of corn-legume based extrudates was studied. Four different types of legumes, chickpea, mexican bean, white bean, and lentil were used to form mixtures with corn flour in a ratio ranging from 10 to 90% (corn/legume). A simple power model was used to correlate porosity with extrusion conditions and material characteristics. The influence of feed rate in the extrudates porosity is incorporated into mean residence time. Porosity of extrudates was found to increase with temperature and residence time and to decrease with feed moisture content and corn to legume ratio. Screw speed did not affect extrudates properties. Expansion ratio showed a similar behavior with porosity. The addition of legumes (protein source) led to more dense products. Comparatively, the usage of white bean in mixtures for the production of snacks, led to a product with higher porosity than those with other legumes.
This study involved the synthesis of kaolin-supported nano zero valent iron (K-nZVI) and the evaluation of its performance for the removal of chromates and nickel from contaminated waters. K-nZVI was prepared by mixing a kaolin sample with a FeCl3 solution, followed by the addition of sodium borohydride for the reduction of Fe(III) to the zero valent state. The effectiveness of kaolin supported nZVI for Cr(VI) and Ni removal was evaluated by conducting batch experiments. The investigated parameters included the amount of K-nZVI per solution volume, the concentration of contaminants and the effect of pH. K-nZVI was found to be more efficient for the treatment of Cr(VI) contaminated waters than for the removal of Ni. Using 1 gram of K-nZVI per liter of solution, it was possible to reduce 20 mg/L of Cr(VI) to less than 5 mg/L within 3 hours. Starting with the same concentration of Ni, i.e.20 mg/L, the final concentration after 3 hours was aproximately 17 mg/L at pH 5.6, and dropped to 10 mg/L when the pH of the suspension was regulated to the value of 7.5. The results suggest the K-nZVI has a rather limited efficiency for Ni removal.
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