| Research on wastewater treatment of Cr (Ⅵ) is continued. Recently, red mud was sintered to make porous ceramisites in Shandong Aluminum Group successfully. It is expected to be used in wastewater research field. According to character of those ceramisites,research on its adsorption and adsorption on Cr (Ⅵ) is completed.Three ceramisites were screened, named as A,B and C. By observing their external appearance and microporosity microscopically, A and B were better than C.By comparing their particle diameter,Specific surface area,total intrusion volume,differential intrusion ,most probability aperture,and porosity intrusion , B was selected as the best. For B,it's particle diameter, Specific surface area,total intrusion volume,differential intrusion , and porosity intrusion 1.2mm,8.386m2/g,0.2759mL/g and 68%,and it's most probability aperture is about 100μm.According to the outcome of single factor experiments, B was selected. Orthogonal table of L9(34) was selected in this research which was about how Cr(Ⅵ) was adsorpted by B statically in artificial wastewater. In this study, time of adsorption,temperature,concentration of Cr(Ⅵ)and pH were selected as the experimental factors in orthogonal test. The result of orthogonal test showed that sequence of those influencing factors was:pH>time>temperature>concentration of Cr(Ⅵ).As the factor,R of concentration is too small,it is unconsiderable in next experiments.According to the result of orthogonal test. It was determined that the optimal conditions were pH=4.5, 3.0h,200mg/L and 25℃Cr(Ⅵ) adsorption onto ceramisite B is quite slow, which requires about 50 hours to reach the balance and the former can be fitted by Freundlich equation; Period of diffusion in interior ceramisite affected the adsorption speed of Cr(Ⅵ) and diffusion coefficient derictly. Specific surface area and pore structure are pacing factor of Cr(Ⅵ) adsorption in B. When the Specific surface area is bigger,and the pore structure is more advanced,the adsorption increases is more efficient.Also, desorption experiment was accomplished in this study. There were three methods used in desorption of Cr(Ⅵ) on ceramisites made from red mud,which were:washing by neutral pure water,acid washing and alkali washing. For those ceramisites, the best method was acid washing. Soaking in HC1 for 2h before acid washing can increase the ratio of desorption,and it reached the peak point after 2h, then the desorption ratio decreased slowly and became steady. |
PDF Full Text Request