The paper studies various modifications of diatomite, aiming at creating sorbents for wastewater purification from heavy metal ions. Diatomite of the Akhmatovskoe deposit of the Penza region was considered as a raw material. The processes of physical and chemical modification of diatomite were investigated. Adsorption isotherms were constructed, quantitative characteristics of adsorption of copper ions on the surface of modified sorbents were obtained. A chemical modification (acidic and alkaline) is proposed, which results in an increased adsorption capacity for heavy metal ions. The applicability of diatomite for the purification of highly concentrated wastewater containing heavy metals is shown.

In this work, the use of the sorption method is proposed for the purification of wastewater from ions of heavy metals. The aim was to study the sorption activity of diatomite in relation to cadmium ions. The studies were carried out under static conditions. The processes of physicochemical modification of diatomite for the extraction of cadmium ions from aqueous solutions were investigated. The influence of time and pH on the value of sorption was studied. The optimal conditions for sorption extraction have been determined. Adsorption isotherms have been constructed, and quantitative characteristics of the values of adsorption of cadmium ions on the surface of modified sorbents have been obtained. The fundamental possibility of using diatomites for the purification of cadmium-containing wastewater has been assessed. Based on the data obtained, it can be concluded that acid activation does not promote adsorption (even negative adsorption is observed), which confirms the mobility of cadmium in the low pH region, it can be assumed that only an increase in alkalinity to the possibility of formation of hydroxocadmium (CdOH)+. Thermal, shows stable adsorption in relation to Cd+2, which suggests the possibility of using such activation of cadmium diatomite and other metals, that is, with complex pollution.