ADSORPTION REMOVAL OF CU (II) USING NI-MODIFIED SILICA GEL

The contamination of surface and groundwater with heavy metals represents a significant threat to environmental safety and the health of living organisms. Consequently, the development of new technologies and the improvement of existing ones to clean water bodies from toxicants of various kinds represents an important task. One of the factors influencing the choice of treatment method is the concentration of the pollutant. It is advisable to use adsorption methods for the post treatment of water environmental to the levels of maximum permissible concentrations. In the context of the implementation of adsorption methods, the selection of sorbents that combine high efficiency and low cost with ease of preparation represents an important factor. The aim of this work is to produce a sorbent based on commercial silica gel and nickel oxide. For its synthesis, the thermolysis method was chosen. A series of materials with varying mass ratios of NiO to SiO2 was produced: 1:1 and 0.5:1. The presence of crystalline nickel oxide on the amorphous surface of SiO2 was confirmed by X-ray diffraction analysis. The main parameters of the porous structure were determined by the method of low-temperature nitrogen adsorption/desorption. With an increase in the amount of the deposited oxide layer, the specific surface area and pore volume of the obtained samples decrease by 1.5-2.5 times compared to the original SiO2. At the same time, the general character of the mesoporous structure is preserved. The optimal conditions for the removal of Cu (II) ions by nickel-containing composites based on silica gel (pH ~ 5.5; sorption time - 1 hour) were investigated. The adsorption kinetics is adequately described by a pseudo-second-order model, which indicates a high affinity of copper for the surface of such samples. It was demonstrated that the modification of the SiO2 surface with nickel oxide results in an enhancement of the sorption capacity of materials with respect to Cu (II) ions. The maximum value of copper sorption on the synthesised samples is 10 times higher than on the original SiO2.