Synthesis Of Iron Oxide Coated Zeolite(iocz) And Its Experimental Investigation On Controlling River Pollutants

Contaminated sediment is one of the river pollutants sources, as the controlling of external pollutant input and improvement of river water treatment, the pollutant caused by internal source(sediment) release becomes outstanding in river environmental pollution, so it is urgent need to control the pollutant release from the river sediment. Among those contaminated sediment treatment technologies, in-situ capping can work rapidly with little disturb to the surroundings, thus it becomes more popular and application. As the current sole or mixture capping materials have no ability on controlling multiple pollutants release or hard to compute coupling its amount for capping, thus limited capping technology application.This study put forward a through of coat iron on zeolite thus get composite material to overcome the disadvantages of sole or mixture capping materials. We optimized the conditions, iron source, coating method and coating time, to get optimized conditions to make iron oxide coated zeolite(IOCZ), and characterized the optimized IOCZ. Then conform its efficiency, survey its treatment ability, impact by other coexistence common ions, and explore its action mechanisms. Do column experiment to simulate the scenery of IOCZ capping control the pollutants release from the contaminated sediment, and explore the relationship between the IOCZ capping thickness and pollutants amount, then ensure the stability of pollutants adsorbed on IOCZ.According to the study, optimized condition is: ferric chloride as iron source, coating as loading method, coat one time. IOCZ got on those conditions has more iron content, much attachment firmness and better performance on treating typical cation(ammonia)/anion(phosphate) pollutants.The density of IOCZ is almost the same with zeolite, and the specific surface area of IOCZ is a little higher than zeolite. The dominate phase of iron oxide coated on zeolite contain Fe OOH and Fe2O3;Fe-OH and Fe-O groups were identified on FTIR spectra. The point of zero charge of IOCZ is around p H8.5.Compared with zeolite, IOCZ has the ability on treating phosphate, sulfide and Cr(VI). As to ammonia and Cu、Zn、Pb, its performance has a little decrease. In the mixed solution, ammonia has no effect on phosphate and sulfide remove, while sulfide has inhibition effect on phosphate treatment. The coexistence common ions(NOM、Cl-、silicate) have no effect on ammonia removal ability. NOM retard IOCZ to treat phosphate, silicate made the treatment capacity and rate both decreased on removing phosphate, while Cl- has no effect on it. Those anions have no effect on sulfide treatment.By exploring IOCZ treatment mechanism, the result shows that ammonia removal.attribute to ion exchange, phosphate treatment ability caused by complex adsorption of the iron oxide film of IOCZ. As to sulfide, its mechanism involve in adsorption and redox action.Column experiment shows that IOCZ could effectively inhibit the release of pollutants from the bottom, and the amount of removed pollutants and capping thickness has relationship of coefficient. The treated pollutants could exist in IOCZ firmly.