Adsorption Performance Of Re(Ⅶ) Onto Modified Rice Husk Adsorbent

In this work, rice husk as the agricultural byproduct was chosen as the raw materials, a variety of chemical modification methods were carried out for preparing aminated adsorbents which were used to effectively remove rare metal, Re(Ⅶ), from aqueous solution.The results are showing as following:(1) Biomass material, rice husk, was chemically modified, using four reagent with dimethylamine(DMA), diethylamine(DEA), ethylamine(EHA) and ethanediamine(EDA), respectively, and then were obtained four types of aminated adsorbents, DMA-CS, DEA-CS, EHA-CS and EDA-CS. This study found that the aminated absorbent EDA-CS that modified with EDA showed a good performance on the adsorption for Re, which might be attributed to amine groups introduced onto the surface of adsorbents and its numbers. The carbonized pretreatment was conducted, and then EDA was introduced onto the surface carbonized rice hust(CCS), which showed a better uptake of Re comparing that onto EDA-CS.(2) Adsorption performance for Re(Ⅶ) removal on aminated adsorbent EDA-CS and EDA-CCS was evaluated, including pH effect, absorption isotherm, adsorption kinetics and, adsorption/desorption regeneration. The pH effects showed that when pH was 6.0, Re(Ⅶ) adsorption capacity onto EDA-CS reached the maximum, when pH was 3.0, EDA-CCS showed a best Re(Ⅶ) adsorption capacity. Adsorption isothermal study showed that the maximum adsorption capacity of Re(Ⅶ) onto EDA-CS and EDA-CCS were 41.7mg/g and 58.3mg/g, respectively. Adsorption kinetics showed that, the first-order kinetic model had a better fit for both of EDA-CS and EDA-CCS. The adsorption/desorption experiments showed that 4mol/L HCl as an eluent performed a best desorptin efficiency for EDA-CS and EDA-CCS, indicating the possibility of regeneration of two kinds of adsorbents. EDA-CCS also showed a good performac in the column experiment. And the desorption process was complished within 30 min with two times concentrated Re(Ⅶ) elluent. It implement the Re(Ⅶ) enrich and adsorbent recycle.(3) The surface morphology and characterristices of the functional group onto raw rice husk and anminated rice husk were studied through scanning electron microscope(SEM) and fourier transform infrared(FT-IR). The Re(Ⅶ) adsorption mechanism were proposed through FT-IR analysis of EDA-CS and EDA-CCS before and after Re(Ⅶ) adsorption. This work exhibited an effective preparation method for high performance Re(Ⅶ) adsorbent, showing a potential for the further large-scale application.