Abstract：
In this study, a novel in situ iron-loaded activated carbon (AFPAC) was prepared by a FeSO4/K2FeO4 impregnation and oxidation combination two-step supported on activated carbon for enhanced removal of Cr(VI) from aqueous solutions. Cr(VI) removal efficiency greatly increased by AFPAC more than 70% than that of fresh activated carbon (AC), which is due to rich iron oxides formed in situ and the synergistic effect between iron oxides and activated carbon. Cr(VI) adsorption behaviors on AFPAC under different water quality parameters were investigated. The maximum monolayer adsorption capacities for Cr(VI) by AFPAC are as high as 26.24 mg/g, 28.65 mg/g, and 32.05 mg/g at 25 °C, 35 °C and 45 °C at pH 4, respectively. Density functional theory (DFT) results showed that the adsorption energy of K2Cr2O7 on the surface of FeOOH was - 2.52 eV, which was greater than that on the surface of bare AC, and more charge transfer occurred during the adsorption of K2Cr2O7 on the surface of FeOOH, greatly promoting the formation of Cr = O-Fe. Cr(VI) removal by AFPAC included electrostatic attraction, redox reaction, coordinate complexation, and co-precipitation. Cr(VI) adsorption process on AFPAC consisted of the three reaction steps: (1) AFPAC was fast protonation and Cr2O72- would electrostatically attract to the positively charged AFPAC surface. (2) Cr2O72- was reduced into Cr2O3 by the carbons bond to the oxygen functionalities on activated carbon and the redox reaction process of FeSO4 and K2FeO4. (3) The inner-sphere complexes were formed, and adsorbed on AFPAC by iron oxides and then co-precipitation.
摘要：
在这项研究中,通过FeSO4/K2FeO4浸渍和氧化组合两步负载在活性炭上制备了一种新型的原位铁负载活性炭（AFPAC），以增强从水溶液中去除Cr（VI）。AFPAC对Cr（VI）的去除效率比新鲜活性炭（AC）大大提高了70％以上，这是由于原位形成的丰富的铁氧化物以及铁氧化物与活性炭之间的协同作用。研究了不同水质参数下AFPAC对Cr(VI)的吸附行为。AFPAC对Cr（VI）的最大单层吸附能力高达26.24mg/g，28.65mg/g,在25°C时和32.05mg/g，在pH4下分别为35°C和45°C。密度泛函理论(DFT)结果表明,K2Cr2O7在FeOOH表面的吸附能为-2.52eV,大于裸露的AC表面上的值，K2Cr2O7在FeOOH表面的吸附过程中发生了更多的电荷转移，极大地促进了Cr=O-Fe的形成。通过AFPAC去除Cr(VI)包括静电引力，氧化还原反应,配位络合,和共沉淀。Cr（VI）在AFPAC上的吸附过程包括三个反应步骤：（1）AFPAC快速质子化，Cr2O72-会静电吸引到带正电荷的AFPAC表面。（2）通过碳与活性炭上的氧官能团结合以及FeSO4和K2FeO4的氧化还原反应过程，将Cr2O72-还原为Cr2O3。(3)形成内球配合物,并通过氧化铁吸附在AFPAC上，然后共沉淀。
