Application Of Modified Zeolite For Ammonium And Cadmium(Ⅱ) Removal From Micro-polluted Water

Clinoptilolite was processed, first, by sodium chloride solution, and then mixed withNa2SiO3and powdered activated carbon. The mixture went through extrusion forming andcalcination to prepare the Silicate-Carbon Modified Zeolite that was used for removingammonium and cadmium(Ⅱ) from drinking water.The Silicate-Carbon Modified Zeolite was analyzed by scanning electron microscopy(SEM), X-ray diffraction (XRD) and thermogravimetry(TG), and its BET surface was comparedwith that of natural zeolite. This study was performed using column experiments, and batch testswere performed under a range of conditions to assess the effect of solution pH, filtration rate,initial ammonium concentration and regeneration methods on the performance and capacity ofthe zeolite in ammonium and cadmium(Ⅱ) removal.These results indicate that natural zeolite and Silicate-Carbon Modified Zeolite couldadsorb ammonium steadily at pH5~9, but that the absorption effect of the Silicate-CarbonModified Zeolite was obvious higher than that of natural zeolite.In varying initial ammoniumconcentration, the Silicate-Carbon Modified Zeolite could remove ammonium effectively but ina longer duration. High ammonium concentration would add load of zeolite and acceleratebreakthrough. The Silicate-Carbon Modified Zeolite column had a prolonged time of operationcompared with the natural zeolite column at each filtration rate. Theammonium-removal-efficiency breakthrough time of both zeolites reduced when the filtrationrate increased. Results indicate that the adsorption capacity of Silicate-Carbon Modified Zeoliteand nature zeolite was0.115mg NH4+-N/g and0.043mg NH4+-N/g, when the pH of the solutionwas7, filtration rate was10m/h and initial ammonium concentration was5mg/L, and was muchhigher than that of natural zeolite. This breakthrough product made from Silicate-CarbonModified Zeolite filtering media would have high ammonium-removal efficiency whenregenerated by three cycles through sodium chloride solution.The adsorption capacity of Silicate-Carbon Modified Zeolite and nature zeolite forcadmium was0.057mg/g and0.016mg/g, when pH was8, filtration rate was10m/h and initialcadmium concentration was50μg/L.