Calcium ion adsorption of <em>Leucaena leucocephala</em> wood biochar activated with coconut vinegar

Abstract

A positive correlation has been reported recently among the number of Chronic Kidney Disease of Unknown Etiology (CKDu) patients and the levels of groundwater hardness.Hence, the need for a low cost and a simple domestic process to reduce the hardness of potable water is identified to improve living standards of low-income communities in these disease affected areas. Biochar has emerged as a low cost adsorbent for water treatment, because of its abundance and cost-effectiveness. This study was aimed to evaluate the ability of natural coconut vinegar, in activating Leucaena leucocephala wood biochar to be used in calcium ion (Ca 2+ ) removal from potable water. Column tests showed a 1.7 fold increase of Ca 2+ adsorption capacity and a 7 fold increase of Ca 2+ retaining capacity upon the vinegar treatment. Batch studies matched with both Langmuir (R 2 = 0.9761) and Freundlich (R 2 = 0.9785) isotherm models. Ca 2+ amount in solutions were measured using flame photometry. Ca 2+ adsorption capacities of raw biochar and activated biochar determined by column tests ranged from 3.10-3.82 mg/g and 5.27-6.68 mg/g respectively while Ca 2+ retaining capacities ranged from 0.16-0.22 mg/g and 1.28-1.4 mg/g respectively. Fourier transform infrared spectra, suggests hydration of the C-O-C bridges of the biochar surface introducing new -O-H groups and possible introduction of carbonyl/ ester/carboxylic functional groups to the biochar surface upon vinegar treatment.According to scanning electron microscopy porosity of the biochar remained stable after the vinegar treatment.

Facile, green approach for aqueous methylene blue dye adsorption: Coconut vinegar treated Trema orientalis wood biochar

“…The experimental adsorption capacity could be greater due to the multilayer physical adsorption. Authors of this study have previously reported the effective use of vinegar-activated biochar in reducing water hardness [11,12]. To our knowledge, no previous studies have reported the adsorption of MB onto Trema orientalis wood biochar or any other form of vinegar-activated biochar.…”

“…Nevertheless, these chemicals used in biochar activation are not accessible to rural communities, are unfavoured due to their corrosiveness, need skilled personnel to handle the procedures, and may even cause secondary pollution. Thus, the importance of finding natural activating agents for biochar, which are safe to handle and attainable for rural communities, was identified [11,12].…”

“…It is obtained by the fermentation of the sap of coconut blossoms, where ethanol undergoes oxidation to form acetic acid without any preservatives or chemicals. Natural coconut vinegar is ~4% acetic acid in water with an approximate pH of 2.5 [11,12]. Trema orientalis is a tropical tree with light wood, soft foliage, and a rapid growth rate which is amply available in Africa and Asia.…”