| The diatomite is the biologic quartzite which is made up of the diatoms and the siliceous remains of the other microorganisms, with a huge ratio surface area and strong surface adsorption. As a new type of natural microporous material, the diatomite has extensive sources, good effect of treating sewage and uncomplicated equipment for subsequent sludge disposal, so it's application prospect is broad and bright.In the paper, we studied the adsorption characteristics and mechanisms for diatomite to adsorb Fe3+ in wastewater (artificial) in detail. We studied the effects of the amount of diatomaceous earth, time of adsorption, temperature, pH value of solution and Fe3+ in the solution by static adsorption. A primary research was done which is based on the adsorption dynamics against Fe3+ by constant temperature adsorption test under different temperature. An orthogonal experiment was operated to study the best adsorption conditions and the dosage of diatomite, time of concussion, temperature, pH value were analyzed in this orthogonal experiment. The effect of flocculant on diatomite adsorbing Fe3+ was examined and a combined technique which is against Fe3+ treatment in industry waste water was formed in combination of adsorption and flocculation.The main findings are as follows:1) The main factors which influence the diatomite on Fe3+ adsorption removal are the nature of diatomite, quantity of diatomite, time of adsorption, temperature, pH value and Fe3+ in the solution. The higher the purity of diatomite is, the better adsorption removal to the heavy metal ionsis. The removal effect of acid diatomite is better than original diatomite.2) In some extent, the removal effect of the Fe3+ is improved with the increase on the quantity of diatomite, time of adsorption, adsorption temperature and pH value, but it decreases with the initial concentration of Fe3+ ions.3) The model of adsorption accords with Langmuir equation. As the temperature rises, the saturation adsorption capacity of diatomite increased. The saturated adsorption of original diatomite increased from 19.08mg/g at 20℃to 27.47mg/g at 30℃, and acid diatomite from 27.40mg/g at 20℃to 32.15mg/g at 30℃. 4) the effects of four factors on diatomite adsorbing Fe3+ were listed according to the degree of importance:quantity of diatomite> pH value> temperature> time of adsorption, and the best condition combination is:the quantity of diatomite 8g/L, time of adsorption 60min, temperature 40℃and pH4.0.5) The adsorption combined with the flocculation was applied to treating Fe3+,which has good application effects. The effect of "acid diatomite+PAC"is better than that of original diatomite+PAC".After the PAC were put in, the diatomite would formed floes and settled soon, the combination of adsorption and flocculation could remove the Fe3+ in waste water and facilitated the segregation of liquid and solid.6) An"acid diatomite+PAC" test was runned to research the treatment of waste water that came from ZhuZhou Yong Li Chemical Limited Company for 20 days. The result of research is shown:the system of this test has a great ability of removing CODCr,SS and Fe3+ in waste water and the quality of water outlet is also good. The removal rate of "acid diatomite+PAC" against CODCr,SS and Fe3+ in the main reactor are>70%,>85% and>99% respectively. The concentration of CODCr,SS in water outlet are both lower than the designated value in level standard in《Integrated Wastewater Discharge Standard》and the concentration of Fe3+ in water outlet satisfy reuse standard of ndustrial waste water.The upper result of research has very important referenced value for diatomite applied in waste water which come from iron industry, and it also supply academic support and technological support. |
PDF Full Text Request