Regeneration of natural Bear River clinoptilolite sorbents used to remove Zn from acid mine drainage in a slurry bubble column

Zinc can be removed from natural acid rock drainage by clinoptilolite, a natural sorbent, in a slurry bubble column. Afterwards, the clinoptilolite can be regenerated. This paper investigates the regeneration of clinoptilolite after it has been used for zinc removal and assesses the effects of regeneration time, regenerant concentration, pH, solution/sorbent ratio, water quality and uptake capacity of the regenerated clinoptilolite. Satisfactory treatment was achieved using 20 g L− 1 NaCl solution in distilled water, adjusted to a pH of 3. Good regeneration was achieved for 1 h agitation in the slurry bubble column, with a regenerant/sorbent ratio of 10 g g− 1. Tests with the regenerated clinoptilolite revealed promising Zn removal capacity.