Preparation Of Iron Modified Red Mud Granule Filter And Its Removal Of Bromate In Water

Red mud is an aluminum industry waste. In this study, in order to realize the comprehensive utilization of red mud, we was using red mud as main raw material for making novel granular filter material, which was applied to remove bromate from aqueous solution.It was providing a new way for red mud utilization and a new ideas for bromate removalFirstly, the spherical filter material with a diameter of 0.8mm under study was made of red mud as the principal raw material. Pulverized coal, bentonite and polyving akohol（PVA）, as additives, which were introduced into a filter material. The effect of pretreatment time, sintering time and temperature, and proportions of raw material was investigated. The results showed that the characteristic of filter material was greatly affected by sintering temperature. The effect of sintering temperature on solubility in hydrochloric acid was investigated ulteriorly, and the optimum preparing conditions of red mud granule filter material was as follows: pretreated at 400℃ for 50 min, sintered at 1030℃ for 40 min and red mud, bentonite and pulverized coal were mixed at a mass ratio of 90:4:6. The BET surface areas of red mud granule filter material was 3.3m2g-1,the isoelectric point was 3.05.Secondly, akaganeite were utilized to obtain a modified filter material. According to the results of characterization, after modification, akaganeite were immobilized on the pore of RMGM. The akaganeite was crosswise arranged in the macropore, which can formed more mesopore and higher BET surface areas. The BET surface areas was15m2g-1. The bromate removal capacity of the akaganeite modified red mud granule filter material was better than that of pure sample. Meanwhile, bromate removal capacity increased with increasing Fe doping content, increased and then decreased with increase of pH. When pH was 7.0, the removal efficiency of akaganeitemodified red mud granule filter material reached 67%. And on this basis, Fe²⁺ was utilized toimprove the structure and performance of red mud granular filter material and to obtain a modified filter material. Based on the characterization results, the BET surface areas was raised to 20m2g-1. the zeta potentials of sample was increased by Fe²⁺, and it was contribute to remove bromate. The bromate removal capacity of Fe²⁺-akaganeite modified red mud granule filter material was largest at pH of 5.0-10.0. When pH was7.0, the removal efficiency reached 94%.Finally, according to the above result, the bromate removal behavior by Fe²⁺-akaganeite modified red mud granule filter material has been investigated particularly, which could be divided into four kinds of functions: electrostatic adsorption, ligand exchange, ion-exchange and reduction. The multifunction surafce of red mud granule material was realized by the loading of Fe²⁺ and akaganeite.