Carbothermal Synthesis Of Activated Carbon-supported Nanozero-valent Iron Particles For The Removal Of Cr(?) And Cd(?)

Nano zero valent iron(NZVI) technology has been widely concerned due to its high efficiency and no pollution to two times. However, due to the existence of NZVI in the water there are easy to reunite, difficult to separate and so on, we usually research or apply through load. The common preparation method of load type NZVI is the reduction method and electrochemical deposition m ethod. However, the above two methods are suitable for the laboratory preparation, which is difficult to be prepared.In this paper, a method which can producing a large amount of load type NZVI and heavy metal removal is explored. The study is based on t he principle of carbon thermal reduction, and the active carbon as the carrier and the electronic donor to prepare the load type NZVI By means of XRD, TEM, SEM, and optimize the preparation process.At the same time, Cr(VI) and Cd(II) were chosen as the target pollutant, and the removal mechanism of Cr(II) and Cd(VI) was discussed and the effect was investigated under different water quality conditions.The project successfully prepared by carbothermal method supported NZVI, and the preparation of supported NZVI with good dispersion, between the individual size ranged from 10 to 100 nm, and investigated the effect of temperature on the preparation of the material and load, where NZVI@AC load will lead to the increase of NZVI particle size becomes large and easy to agglomerate, preparation of high temperature is conducive to the formation of NZVI@AC in Fe0, Fe in NZVI@AC prepared by 800? was mainly in the presence of zero valence iron.The removal of Cr(VI) was removed by passivation experiments and desorption experiments showed that Cr(VI) was removed by the reduction of the core and the external passivation layer; the removal of Cd(II) mainly depends on the adsorption of NZVI surface passivation layer. The adsorption of Cr(VI) and Cd(II) was consistent with Langmuir isotherm model and the maximum adsorption capacity of Cr(VI) and Cd(II) was 26.385 mg/g and 87.715 mg/g.After the process optimization of NZVI@AC prepared by Cr(VI) and Cd(II) on the removal results show that in a certain concentration range of Cr(VI) initial concentration is lower and lower initial p H, the removal rate is high; in a certain range of concentration of Cd(II), the higher the initial the initial concentration of p H is higher, the higher the removal rate of carbonate, bicarbonate, sulfate; there are not conducive to the removal of Cr(II), but for Cd(II) removal, but the calcium and magnesium ions i nhibited the removal of Cr(VI) and Cd(II); humic acids had inhibitory effect on Cr(VI) and Cd(II).