Removal of nickel ions from industrial wastewater using immobilized sericite beads

To efficiently remove nickel ions from actual industrial wastewater which is coexisted with high sodium concentration, powdered sericite was immobilized as a bead form by entrapment method using sodium alginate. The beads with surface area of 7.1 m2/g were not untangled to ∼45 °C and ∼pH 11.0 in wastewater and have excellent mechanical strength and swelling characteristics. It was also confirmed that natural sericite beads did not appear the characteristic peak for nickel ions, nickel-adsorbed beads clearly shows the peak of nickel ions as about 4.00 wt% by means of SEM–EDX analysis. The effect of sodium ions on nickel removal was negligible and the maximum adsorption capacity using Langmuir equation was 10.743 mg/g at pH 7.5 of wastewater in batch. The nickel ions can be removed from actual wastewater over 95% up to 90 (1.0 mL/min) and 140 bed volumes (0.5 mL/min), respectively and 7 bed volumes of 20 mM of HNO3 solution was required to get 96% of nickel desorption in continuous process using packed-bed column. Also, breakthrough point of nickel ions could be still maintained as 130 up to the 2nd cycle by reused immobilized sericite beads.