Abstract
Lime sludge is one of the major unutilized industrial reject and has promising potential as an alternative source for calcium. The present work illustrates a viable process developed for rapid and cost-effective extraction of calcium mineral values from the alkaline lime sludge. A comparative assessment of formic and acetic acid used for extraction of calcium from the reject has been discussed. The chemical method at ambient conditions extracted remarkable amount of calcium from lime sludge. Detailed analytical characterization revealed that recovery efficiency of calcium is much more superior for acetic acid. The organic salt of calcium obtained was re-crystallized for better purity and further treated to obtain inorganic salt viz chloride / nitrate as precursor to convert into nano calcium oxide by sol-gel method. The final product was characterized by XRD, ICP and SEM. The average crystallite size of obtained nanoparticles was 42.44 nm based on XRD analysis results. (C) 2020 Elsevier Ltd. All rights reserved.