| Red mud is a polluting waste slag which is discharged by the manufacturing process of alumina. How to recycle it as a resource has become important in environmental protection field. In this study, Bayer red mud as the main raw material and supplemented by other industrial material were used to prepare red mud ceramic porous material. XRD, XRFA, TG-DSC, SEM and ICP-MS were used for analyzing the chemical composition, phase composition, temperature characteristics, microstructure, and heavy metals leaching of raw material. Porosity, water absorption, bulk density has been selected as based index to evaluate physical properties of ceramic. Acid and alkali resistance as an indicator investigated the chemical stability of ceramic. The MIP test investigated the changes of the distribution of ceramic internal pore during the process of roasting. With two different pore-forming materials used to control the porosity, the principle of pore-forming was analyzed. The red mud-based porous ceramic material was modified by Fe-CTS. Effect on Cr(VI) adsorption, desorption and regeneration by using Fe-CRMC has been researched. The results were as follows:(1) The mineral composition of red mud was complicated, Fe2O3was the main chemical composition and it was not suitable to prepare the porous ceramic separately. The ignition loss of it was10.97%. Its internal hydrated minerals and calcite can be decomposed as gas at a high temperature and generated porous structure.(2) The optimal thermal system that the temperature of preheating treatment was400℃, the time of preheating treatment was20min, the temperature of sintering treatment was1140℃, the time of sintering treatment was40min. The porosity, water absorption, bulk density, alkali resistance and acid resistance of B6(the additive amount of red mud at60wt%) was respectively29.87%,8.79%,1.57g·cm-3,98.8%and97.65%.(3) Under the optimal thermal system, the pore-forming materials was added (graphite and dolomite) into B6to control the porosity. When the additive amount of graphite GB-4at20wt%, the porosity, water absorption, bulk density, alkali resistance and acid resistance of porous ceramic was respectively55.24%,36.73%,1.36g·cm-3,97.6%and93.5%. When the additive amount of dolomite DB-4at20wt%, the porosity, water absorption, bulk density, alkali resistance and acid resistance of porous ceramic was respectively43.69%,36.24%,1.73g·cm-3,98.8%and81.4%.(4) The preparation conditions has been researched for the modified adsorbent material of the porous ceramic. Unmodified B6, GB-4and DB-4have the capacity of adsorption. GB-4has more significant effect on Cr(Ⅵ) adsorption. After the concentration of Fe-CTS of0.01mol·L-1has modified Fe-CRMC. The removal rate of Cr(Ⅵ) increased from28.38%to84.25%.(5) The adsorption and desorption characteristics of Cr(Ⅵ) in waste-water on Fe-CRMC has been researched. The concentration of Cr(Ⅵ) was20mg·L-1, pH value of5.0, the dosage of Fe-CRMC was40g·L-1, the adsorption reaction time was180min. The removal rate of Cr(Ⅵ) was94.22%. The adsorption saturated of Fe-CRMC after desorption on0.01mol·L-1NaOH, the effect of desorption was stable and the regeneration performance was the best. After three times regeneration, the adsorption rate of Cr (Ⅵ) felled to72.69%from87.46%. |
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