Research On The Preparation Of Montmorillonite Granule Adsorbent And The Adsorption For Ammonium In Wastewater

This subject is launched to find out an efficient solution to take back the clay powder absorbent from the waste water and to reuse. Up to now, the study of formed clay absorbent was mostly about the technology of powder granulation. Little study was done about the immobilized technology of clay powder in wastewater treatment. In this thesis, under the basis of montmorillonite as material and polyvinyl alcohol (PVA) as entrapment agent, the preparation and the mechanism on the ammonium adsorption of the montmorillonite-granule-adsorbent was studied systemically.On the preparation experiment, there are 4 factors affect the intensity and the adsorption of the montmorillonite-granule-adsorbent. The optimum direction from the study of 4 factors is 10% PVA, 0.2% sodium alginate, 1:1entrapping rate and 24 hours immobilized time. In all the factors, the concentration of PVA played an important role. The montmorillonite-granule-adsorbent which was made with above condition had good mechanical intensity and ammonium adsorption, and it was transported easily through the treatment of dehydration. Furthermore, the montmorillonite-granule-adsorbent could be reused as plant soil.Results from the research of the montmorillonite-granule-adsorbent adsorbing NH₄⁺, indicated: (1) With the concentration of the wastewater reducing, the remove rates of ammonium gradually increased. When the concentration of the wastewater lower than 10mg/L, the remove rates of NH₄⁺ were 99.8%.(2) Absorbent has better ammonium adsorption in a wide rage of pH which is 4 to 10. (3) Equilibrium adsorption of the montmorillonite-granule-adsorbent for ammonium fitted the Langmuir isotherm, and the max adsorption capacity is 3.21mg/g. (4)Ammonium adsorption capacity of the montmorillonite-granule-adsorbent under dynamic condition was lower than its max adsorption capacity. The process of ammonium adsorption of the montmorillonite-granule-adsorbent accorded with the first order kinetics.The mechanism on the adsorption of the montmorillonite-granule-adsorbent was investigated by testing its characteristics by means of XRD and SEM instrument .The results show that the expanding of the pore and the decreasing of the ion-exchange capacity were causing by the macromolecule of PVA exchanged with the cation in the montmorillonite and then entered into the interplanar spacing of the montmorillonite in the process of the montmorillonite-granule-adsorbent preparation. Moreover, it's the reason of the montmorillonite-granule-adsorbent have great ammonium adsorption in the concentration below the 10mg/L, and however have lower ammonium adsorption capacity.