Study On Competitive Adsorption Process Of Fluorinion & Phosphate In Fix-bed By Modified-pullulan

Fluorine is an essential element for human body, high concentration fluorine in drinking water will extremely harm body health, and China is one of the most affected countries in the world. Phosphorus are widely used in industry and agriculture, but excess phosphorus lead to algae blooms in water, reduce dissolved oxygen in water and also water quality. Many industries discharge wastewater contain high concentration of fluorine and phosphorus. Adsorption stands out for its low cost, high efficiency, and simple operation, in former studies we found that modified-pullulan adsorbent performs well in fluoride and phosphate removal, this thesis studies the column performance of fluoride and phosphate removal by modified pullulan adsorbent in fixed bed on the basic of former static studies, discuss the competitive adsorption of fluoride and phosphate in dynamic condition.This thesis studies the influence to breakthrough curve of fluoride and phosphate, as well as the whole adsorption process of fixed bed operation parameter and ambient conditions. Results indicate that: 1. the whole system can well adapt the variation of ambient conditions. Operation temperature has little influence to adsorption effect, best result can be obtained at room temperature 25?.initial fluoride/phosphate concentration has smaller affect than they are adsorbed respectively, 10 – 20 mg/L initial ion concentration is acceptable, and best result come when fluoride to phosphate concentration ratio is 1:1. Initial pH has larger impact to the system, and it performs better when the water is acidic or alkaline, when initial pH=4, the discharge is nearly neutral. 2. Operation parameters have obvious influence to system. Higher bed weight and slower flow rate benefit adsorption performance, with 6g adsorbent dose and 8m L/min flow rate can get the best adsorption result. 3. The breakthrough curve of fluoride and phosphate in competitive adsorption is similar with each other. In fixed condition, phosphate has higher saturated capacity, longer breakthrough and saturated adsorption time, lower adsorbent expend rate, indicates that phosphate dominate in competitive adsorption, while it affect more in competitive adsorption.This thesis also studies the fit status of breakthrough curve with Thomas and Yan model, it turns out that Yan model fit better than Thomas, but the adsorption capacity it calculated is too much lower than experimental data, while Thomas model can give a relatively accurate prediction. In addition, the fitting situation of fluoride and phosphate breakthrough curve in competition adsorption is similar with their separate adsorption.