Research On Modified Red Mud’s Performance Of Phosphate Adsorption

Red mud, which is a by-product from alumina industry, is not only in large quantity butalso causes serious pollution to the environment. For the purpose of treating waste with waste,firstly, the red mud were two ways (roasted activation and acidified activation)modified andthe performance of theirs phosphate adsorption were studied.Then for the purpose ofindustrial applications, red mud was used as the main raw material to produce red mudgranular adsorbent in this study, and this novel adsorbent was applied for phosphate removalfrom aqueous solution. The results were listed as following:(1)The phosphate adsorption performance of two modified red mud has been enhancedcompared to the original red mud, especially roasted red mud, the adaptability of adapting tothe external environment has also been enhanced.(2)Alkaline environment are unfavorable to the adsorbed phosphate of red mud, the bestspH of the original red mud and acidified red mud is3, roasted red mud is resilient to theacidic environment and adsorption effects of roasted red mud are well(pH is2to5).(3)Study the kinetics and adsorption isotherm model of phosphate adsorption, the resultis that Liquid film diffusion model, Pseudo-second-order kinetic model and Generalizedisotherm model can better describe the adsorption characteristics of original red mud andmodified red mud.(4)By sweeping electron microscopy(SEM), specific surface area analysis, we can knowthe surface of original red mud and roasted red mud are roughness, acidified red mud isslightly glossy; Three kinds of red mud are aggregate structure,with rich pores, and more forthe big hole, but not uniform; Specific surface area, pore volume and average pore size ofroasted red mud were increasing; The pore volume and average pore size of acidified red mudhas increased, but the specific surface area are lower; Red mud showed greater aggregatestructure after adsorption, indicating that new substances are generated in the surface of redmud.(5)By energy spectrum analysis(EDS), X-diffraction(XRD) and infrared spectroscopy(FTIR) analysis, we can know red mud is rich in metallic elements, the highest metallicelements is calcium. The main component is calcite(CaCO3), hematite(Fe2O3), silica(SiO2),etc.; Component of red mud after activation are not changed significantly; After adsorption,a large amount of phosphate appears in red mud.(6)Red mud, fly ash, sodium bicarbonate, bentonite mixed by a ratio of16:4:2:1andmade red mud granular of6mm, phosphate concentration is15mg/L, the dosage is5g/L,temperature is25℃, under the conditions of this, red mud granular of original red mud’sremoval rate is55.3%, red mud granular of roasted red mud’s removal rate is95.5%.The core purpose of this study is to supply basis of using red mud in phosphate removalfrom wastewater.