Preparation, Characterization and Application of Rice Hull-Derived Zeolites in Water Treatment

This study aimed to prepare zeolite from rice hull, characterize the prepared zeolite and apply it in the removal of nitrate in water. Pretreatment of rice hull before ashing was done using distilled water and 1M HCl. Purity of the rice hull ashes obtained in the process was verified by determining their percent carbon content. Using EDX, the alumina and silica ratios were calculated from the data gathered. SEM was used to determine the shape and pore size and XRD method to know the possible crystal lattice of the prepared zeolites.The rice hull washed with water (RHA-W) has 21:16 (Si:Al) framework ratio while that acid-washed (RHA-A) 23:17 (Si:Al) which could mean that the Si-Al framework ratio of the samples are 1.3:1 and 1.4:1, respectively. SEM scans at 7500x magnification revealed that zeolites derived from RHA-W has bigger pore sizes (2 ?m) compared to those derived from RHA-A with approximately 1?m diameter. Using XRD spectroscopy, the rice hull-derived zeolites possible lattice was determined and both were not simple cubic crystals. The trapping and exchanging capacity of the prepared zeolites were determined by treating a water sample with 69.0 ppm of NO3- and loading it with 0.2 g zeolite per liter of solution. Results show that the zeolite derived from RHA-W was able to decrease the concentration of nitrate in water by 99.11% while that derived from RHA-A by 99.26% while only 98.77% for the commercial zeolite.