Surface morphology of the EMCMCR before and after adsorption was observed by SEM, and the SEM images are shown in Fig. 3.
Before adsorption, irregular surface structure and many pores in the surface were observed, which may exist as amine groups.
It is also considered helpful for mass transfer of Cr (VI) ions to EMCMCR.
After absorption, the adsorbent surface became abnormal and a great deal of crystal adhered to the surface.
These images prove that Cr (VI) ion was adsorbed by EMCMCR into its pores and developed a layer of Cr (VI) substance on the surface.