Study on the adsorption process of Cd(II) by Mn-diatomite modified adsorbent

[Display omitted] •The experiment simulated the concentration of Cd (II) in the real mineral wastewater.•The modification mechanism of Cd (II) on the adsorbent were analyzed.•The results showed that the adsorption effect of the adsorbent on Cd (II) was higher.•As modifier, diatomite was favorable for the recovery of Cd (II) after adsorption. Using adsorbents to remove cadmium, a highly toxic element, from the aqueous solution is an effective method. Cd (II) adsorbent was prepared from modified diatomite, using NaOH and MnCl2 as compound modifiers. The microstructure of the samples was studied by SEM, IR, and XRD. And the adsorbent modification and the adsorption process of Cd (II) were analyzed. The results showed that the active silane chain on the diatomite matrix surface was opened during the modification process. And then the manganese modified material was grafted on the active hydroxyl site and the opened silane chain respectively. And some Mn4+ substituted Al3+ were grafted on the surface of the diatomite. Compared with diatomites, the specific surface area of the adsorbent grafted with manganese oxide was increased by about 8 times, and a large number of manganese hydroxyl sites were formed on its surface. Thus, compared with the unmodified diatomite, the adsorption rate of Cd (II) on the modified adsorbent was increased to 98.69%, suggest that modified diatomite could be employed as an efficient adsorbent for the removal of Cd(II) from wastwater.