Removal of Nickel Ions from Wastewater and Industrial Solutions

This paper presents conventional and innovative technologies for wastewater and industrial solution purification from Ni2+ ions and accompanying non-ferrous metals. Several methods including sorption, extraction, flotation, chemical, electrochemical, membrane and microbiological separation of impurities from the liquid phase are introduced. Chemical methods involve nickel deposition in the form of insoluble compounds (hydroxide, carbonate, bicarbonate, sulphide, dimethylglyoximate), or metal powder by adding certain reagents. Carbon, aluminosilicate and some other inorganic materials in initial and pre-modified forms, as well as weakly acidic, strongly acidic, weakly basic, including chelate ion-exchange resins and fibres are used for sorption. The extraction of nickel ions from the liquid phase is carried out with the derivatives of organophosphorous, carboxylic acids, as well as with materials that combine the properties of solid sorbents and liquid extractants. Nanofiltration and reverse osmosis are the most relevant methods among membrane purification methods. Foam separation of nickel ions during flotation is carried out using anionic and nonionic surfactants. Electrochemical methods include electrocoagulation, electroextraction, electroflotation, and electrodialysis using soluble and insoluble electrodes, as well as galvanic coagulation without connection to external power. Living and non-living biomass of some species of bacteria, fungi, algae, as well as their complex mixture in the form of activated sludge can be deployed for microbial extraction of nickel from aqueous media. The above purification methods are considered on the basis of case studies, both generally applicable and specific ones. Their advantages and disadvantages are briefly described.