The Isolation of Lignin from Coconut Fiber as Bioadsorbent of Cr(III) in Lake of University of Indonesia

Abstract

Environmental pollution caused by heavy metals becomes a world problem. Various methods have been developed, one of which is the method of adsorption. Adsorption of heavy metals can be done using lignin. Lignin has been successfully isolated from coconut fiber by dissolving it in an alkaline solvent, NaOH. Next, it is deposited in an acidic atmosphere. The precipitate is filtered and dried using an oven with a temperature of 60°C and then placed in a desiccator to remove water in lignin to obtain pure lignin. The isolation result was characterized by using FT-IR instrument and an adsorption test was conducted on chromium heavy metal. The adsorption test was performed on a mass variation of 0.2; 0.3; And 0.5 gram and contact time 60; 90; And 120 min and an increase of% adsorption per mass increase and contact time. The lignin permeability for Cr metal ions has the best effectiveness for contact time of 120 min and 0.5 gram of adsorbent mass with adsorption% of 76.2% and 57.87%, respectively. Optimum time and mass are used for testing of aquatic samples at Lake University of Indonesia to determine the capacity of absorption of lignin against Cr metal presents in the sample. The concentration of chromium ion before and after adsorbed by isolated lignin from cocopeat fiber are 117.00 ppm and 6.89 ppm, respectively. The isolated lignin adsorption capacity of Cr in the sample of Lake University of Indonesia is 94.11%.