Pectin extraction from cocoa (Theobroma cacao L) pod husk and its application as cadmium (Cd) metal adsorbent

Abstract

The cocoa pod contains pectin, which has hydroxyl and carboxyl groups to adsorb Cd metal ions. This study aims to determine pectin's yield from cocoa pod husk (CPH), characterization of pectin, and optimum condition of Cd metal ion adsorption by varying pH, contact time, and Cd metal ion concentration. Pectin was extracted from CPH powder using 5% HCl at 95 °C for 2 hours, followed by pectin precipitation using 96% ethanol. The yield of pectin from CPH was 6.169%. Identification of functional group using FTIR spectrophotometer, obtained absorption at wavenumbers (cm-1): 3277.06 (-OH), 2945.30 (-Csp3H), 1666.50 (C=O), 1384.89 (-CH3), 1157.69 (-CO), and 1082.07 (-C-OH). The pectin characteristic was the moisture content of 0.039%; ash content of 10.634%; the equivalent weight of 757.77 mg; methoxyl content of 5.303%; galacturonic acid content of 73.01%; and the degree of esterification 41.23%; Analysis of the absorbed Cd metal ion using AAS. The optimum conditions of Cd metal ion adsorption by pectin was obtained at pH 11; contact time 30 minutes; with the percentage of adsorbed get 99.76% and adsorption capacity of 2.4927 mg/g at 50 ppm of Cd metal ion concentration.