Experimental Study On Removing Phosphorus By Natural And Modified Zeolite

In recent decades, the eutrophication phenomenon caused by excess nutrients in the water in the world occurs frequently. Although the phosphorus content in water less than that of ammonia. Phosphorus occupy an increasingly influential role in the eutrophication phenomenons of ocean and lakes. Therefore, reducing sewage and industrial wastewater phosphorus problem has been gradually focused on by domestic and foreign researchers.The research object of this test is removal phosphorus sorption by static oscillation adsorption experiments. The type of adsorbent is Baiyin of Gansu province natural and modified zeolite materials. The first half use of phosphoric acid root simulated wastewater instead of actual wastewater as the research object, and in the rear part to makes a preliminary study of removing phosphorus element from the actual aquaculture wastewater and surface runoff. To made some characterization about important component and structure of the natural zeolite.There are SEM,EDS,BET to determine the composition of natural zeolite sorbent materials and specific surface area of natural zeolite adsorbent material. This paper studies conducted phosphorus adsorption characteristics of natural and modified zeolites include, First, to determine the modified method of Baiyin natural zeolite and utilize FeCl3 solution to make a modified zeolite adsorbents. And further optimize the process of zeolite modified conditions by various factors(temperature roasting, baking time, natural zeolite particle radius, the concentration of FeCl3 solution) to determine the optimal modification conditions. Next, through compared phosphate adsorption capacity of FeCl3 modified adsorbent with prior to modification. NH4+ and phosphorus removal of natural zeolite will be also compared with FeCl3 modified adsorbent.To study various interference factors in the process of FeCl3 modified zeolite removing the reaction of phosphoric acid root from wastewater such as simulation of initial concentration, static test reaction contact time, reaction temperature, p H and contact FeCl3 modified adsorbent dosing quantity. To get the optimal reaction conditions of the optimal reaction conditions. Application of the modified zeolite to actual aquaculture wastewater and surface runoff in the sewage and investigation of modified zeolite ability of practical application. To draw Langmuir and Freundlich adsorption isotherm of removal reaction process according to the modified natural zeolite and modified zeolite adsorbent removal data. Then make dynamics, thermodynamics analysis of the removal process and discussion removal reaction mechanism FeCl3 modified adsorbent. The experimental results are as follows:(1) SEM images show that the surface of the natural zeolite is very rough and there are a lot of cavity and porosity inside the zeolite. By EDS to determine the main components of natural zeolite is aluminum, silicon, iron and other elements. Among them, Al 12.47% of the total elements, Fe is 13.44% of the total elements, element content of Si and Al’s ratio is 4.13. The corlor of natural zeolit in this paper is brick red due to Fe elements. The zeolite particle specific surface area is 10.08 m2/g.(2) All the four factors influence the process of FeCl3 modified natural zeolite through the single factor experiment. Among them, phosphorus adsorption capacity of FeCl3 modified adsorbent become thicken with FeCl3 solution increased, but lower with increasing calcination temperature in a muffle furnace. With the growth of roasting time in a muffle furnace for phosphorus removal incrementally. Removal of the FeCl3 modified adsorbent better with particle size becoming smaller. The most important factors can be obtained by orthogonal experiment is the calcination temperature. Calcination temperature can not too high. Otherwise it will destroy the internal structure of the zeolite pores. Particle concentration, roasting time and FeCl3 solution zeolite are follow with the calcination temperature. Optimum conditions are modified as follows: temperature is 200 ℃, the adsorbent particle size is 80 to 100 mesh, baking time is 4h, FeCl3 concentration is 4.5mol / L.(3) Disturbances(concentration of phosphate, oscillation time, oscillation temperature, p H and the dosage) of modified zeolite phosphate removal process are been researched: phosphorus removal increase with FeCl3 modified zeolite dosage rising. But the dosage is very small growth after 1.5000 g. The FeCl3 modified adsorbent phosphorus removal rapid increase at first. Removal volume growth leveled off when phosphorus wastewater initial concentration is 140mg/L. The process has the nature of the "fast adsorption, slow equilibrium". FeCl3 modified adsorbent for the removal efficiency of phosphorus due to temperature increase. When the p H less than 8, zeolite remove the amount of phosphoric acid root grows with the p H value growth. After p H is 8 removal effect is best but removal effect is reduced when p H continue to grow.(4) The adsorption effect of FeCl3 modified zeolite adsorbent is obviously enhanced compare with before modification. The phosphoric acid root removal of zeolite slowly into balance after 900 min. FeCl3 modified zeolite reach to flatten slightly shorter time,720 min,and the equilibrium adsorption quantity is 3.2798 mg/g. The adsorption equilibrium ratio increased 3.2055mg/g than before. The NH4+ removal of FeCl3 modified zeolite has large difference with PO43-,the effect is not very good.(5) R2 of freundlich model is greater than the R2 of Langmuir, Freundlich and Tempkin model. Remove phosphate reaction of FeCl3 modified zeolite is not a simply monolayer adsorption, but it is a multilayer reaction of uneven surface more in line with the Freundlich model.The number of 1/n is 0.2056 in the Freundlich model of FeCl3 modified zeolite remove phosphate reaction. So the adsorption reaction belongs to optimization with the easier adsorption reaction. The thermodynamic analysis shows that the reaction of the modified adsorbent ΔS is 140.67J/(mol?K) and ΔH is 42.371KJ/mol. Fully proved that the reaction process is endothermic and entropy increase physical adsorption reaction. Kinetic analysis showed that pseudo second-order kinetic equation correlation coefficient R2=0.9988 and the R2 is maximum. More accurately describe the dynamic process of the FeCl3 modified zeolite. Adsorption reaction process is not a simple process, but fast and slow alternating complex process.(6) Natural and modified zeolite applied into the actual wastewater, the ammonia nitrogen removal rate to surface runoff by natural zeolite can reach 78.9%, the Ammonia nitrogen residual concentration is 0.327 mg/L, conform to the integrated wastewater discharge standard GB8978-1996. The FeCl3 modified zeolite adsorbent applied in practical aquaculture wastewater,the ammonia nitrogen adsorption capacity can reach 2.21 mg/g;For phosphorus adsorption capacity is 0.99 mg/g, removal rate as high as 75%. After processing the ammonia nitrogen residual concentration is 67.39 mg/L, the residual concentration of phosphorus was 4.62 mg/L, conform to the discharge standard of pollutants for livestock and poultry breeding GB18596-2001.