Adsorption of chromium ions by candlenut shell based carbon activated with H3PO4

Abstract

Abstract Candlenut shell based carbon which was chemically activated using a solution of phosphoric acid and modified with nitric acid has been used to adsorb chromium ions (Cr(VI)). This study aims to examine the effect of phosphoric acid activation on the surface area of the candlenut shell carbon and the effect of nitric acid on the adsorption capacity of metal ions Cr (VI). The study was carried out by activating the candlenut carbon with 10% phosphoric acid for 24 hours then modified with 6 N nitric acid for 24 hours. The activated carbon that has been modified is then optimized with several parameters, namely time, pH and the number of adsorbents to maximize the performance of activated carbon. The surface area of candlenut based activated carbon was determined by methylene blue method and the adsorption capacity was measured using Atomic Absorption Spectrophotometer (AAS). The results showed that the carbon surface area before and after activation increased from 1557.3 m2/g to 1669.5 m2/g, respectively, and the surface area increased dramatically after HNO3 modification to 2090,8 m2/g. The adsorption capacity to the metal ions (Cr(VI)) tends to follow the Langmuir isotherm model which is equal to 20.4 mg/g.