Preparation Of Modified Zeolite And Its Application In Wastewater Treatment

This research focused on the best technological conditions to make HDTMA modified zeolite and rare earth modified zeolite. The performance and the best technological conditions on adsorbing Cr(Ⅵ), phosphate and ammonia.The results showed that:①The best technological conditions to make HDTMA: the addition amount of modifiers in natrual zeolite was 2.5%, the modification temperature about 20℃, storing temperature 100℃, the modification time 2 hours. HDTMA modified zeolite adsorbing Cr(Ⅵ): best pH range of the solution was below 6, best adsorben dosage was 0.5g, surge time Was 30min. Influent Cr(Ⅵ) concentration was 25mg/L, the volume of water was 25mL. Removal rate of Cr(Ⅵ) was above 92%. The saturated adsorption capacity was 3.34mg/g at 15℃. Langmuir equations could describe the absorption isotherm data, Elovich formula and parabola pervasion equation was used to describe the adsorption rate. The amount of chromate absorbed by the modified zeolite decreased with the increasing in ionic strength, which suggested that the electrostatic interaction between the modified zeolite and chromate was the major mechanism.②The best preparation method of rare earth-zeolite adsorbent: the addition amount of La³⁺ in natrual zeolite was 27.7%, accommodate the pH value of infuse solution was above 10, infuse time was 16 hours, at 100℃dry the earth-zeolite adsorbent 1h and at 400℃bake it 1h. Rare earth-zeolite adsorbent removed ammonia nitrous: best pH range of the solution was 2～6, best adsorbent dosage was 20g/L, surge time was 2 hours. Rare earth-zeolite adsorbent removed phosphate: best pH range of the solution was 2～6, best adsorbent dosage was 4g/L, surge time was 1.5 hours. The volume of water was 25mL, influent ammonia nitrous and phosphate concentration was 25mg/L and 50mg/L. Removal rate of ammonia nitrous and phosphate was 60.3% and 97.2%. The saturated adsorption capacity was 10mg/g and 14mg/g at 20℃. Rare earth-zeolite adsorbent's adsorption to phosphate and ammonia nitrous accorded with Langmuir equation. Rare earth-zeolite adsorbent had well disposal effect to actual living sewage, compared with biology method, it had better removal effect to phosphate, ammonia nitrous and COD. The water after this disposing could achieve the No. one standard in Discharge Standards of Pollutants for Municipal Wastewater Treatment Plant.Modified zeolite and natural zeolite was characterized using IR spectroscopy, XRD and SEM:①Organo-zeolite' layer spacing can increase. Cationic surfactants was absorbed on the Surface of natural zeolite, and enhanced the adsorption capacity to the anionic pollutants.②The Rare-Earth was absorbed on the Surface of natural zeolite, and enhanced the adsorption capacity to the phosphates.