Cost-effective and non-toxic method to modify clay to increase the hardness adsorption capacity of clay
Bingun T Perera, RMH Rajapaksha, RCW Arachchige, IRM Kottegoda
Hardness of the drinking water has been considered as one of the major causes of Chronic Kidney Disease of unknown etiology (CKDu) in the Northern part of Sri Lanka. The present study was ultimately aimed at removing the water hardness using clay as a cheap renewable adsorbent. The hardness adsorption capacity of raw clay was increased by treating clay with NaCl(aq). The present methodology was proposed due to low toxicity, low cost, and high commercial availability of clay and NaCl. Clay samples were collected from Deniyaya Sri Lanka. The particle size reduction of clay was achieved by treating raw clay with NaCl(aq) at different durations at 303K temperature. During the study, adsorption of Ca2+ and Mg2+ (the water hardness) was analyzed using EDTA titration following the standard APHA method protocols. The highest adsorption was observed at 33 hours of treatment. XRD spectrum of raw clay showed a sharp strong diffraction peak of the sample at 2θ = 22.45° which is a characteristic peak of Kaolinite-2M with 97.1% abundance. XRD spectrum of treated clay showed considerable changes that the clay consisted of kaolinite (44%) and Orthoclase (56%). It was noted that with the increasing of treating time, although the particle size decreased, after some point small clay particles tend to aggregate again reducing cation adsorption capacity. Treated clay enabled to reduce the total hardness by 96% of the tested water obtained from CKDu prevalent area.
Bingun T Perera, RMH Rajapaksha, RCW Arachchige, IRM Kottegoda. Cost-effective and non-toxic method to modify clay to increase the hardness adsorption capacity of clay. International Journal of Chemical Science, Volume 4, Issue 1, 2020, Pages 22-27