Water purification of technogenic solutions from nickel (II) ions by a combined process

The option of combined purification of aqueous solutions from nickel (II) ions is based on sorption technologies using electrically generated aluminum hydroxide with an amorphous porous structure in the form of a hydrogel and a developed sorbing surface. Such aluminum hydroxide has a micellar structure and can be described by a colloidal particle: {[m Al(OH) 3 ] nAl(OH) 2 + (n-x) OH - } x+ хOH - . Purification is associated with the phenomenon of sorption of a contaminating ion on the surface of the sorbent due to the dispersion interaction. The limiting value of nickel adsorption at 298 K and pH 7.6 was 8.3 mmol/g, the consumption of electricity corresponded to 9.5 A.h with an optimal electrocoagulation time of ten minutes and a current density of 1.6 mA/cm 2 . The advantages of the electrocoagulation method using aluminum electrodes, in comparison with other wastewater treatment methods, are the simplicity of the equipment manufacturing and ease of maintenance. The purification efficiency during electrocoagulation treatment was 86%. Aftertreatment of technogenic aqueous solutions was performed using carbon sorbents in a slightly alkaline medium at pH 9.8. The sorption value of nickel reaches 0.25 mmol/g. A feature of the combined technology for extracting nickel from aqueous solutions is the disinfection of water with an improvement in its granoleptic properties and the possibility of avoiding secondary contamination of the treated aqueous solutions with applied reagents.