Optimization of Manufacturing Conditions for Activated Carbon from Coffee (Coffea Arabica L.) Bean Waste by Chemical Activation

Pyrolysis is one form of energy recovery process which has the potential to generate oil, gas and char products. The char becomes an attractive by-product, with applications including production of activated carbons that is useful as a sorbent for wastewater treatment and air pollution control. In this work, activated carbon was prepared from Coffee (Coffea Arabica L.) bean waste collected from local coffee houses. Char from pyrolysis of coffee bean waste at 900 degrees C contained high fixed carbon and low volatile content that was favorable for subsequent activation process. The char was activated via chemical treatment with sodium hydroxide (NaOH) at five different NaOH : char ratios (1:1, 2:1, 3:1, 4:1 and 5:1) and heat treated at 400 degrees C for 15 minutes using a fixed bed reactor under nitrogen atmosphere with a flow rate of 100 mL/min. Result shows that NaOH works effectively as dehydration reagent around 400 degrees C. Under the experimental conditions investigated, impregnation ratio of 1.0 was found to be suitable for producing high-surface area activated carbon. The surface area and total pore volume of activated carbons, which were determined by application of the Brunauer-Emmett-Teller (BET) and t-plot methods, were achieved as high as 802 m(2)/g and 0.80 cm(3)/g, respectively. The chemically activated carbons were found to be mainly type I carbons and had high adsorption property (Methylene blue adsorption = 284 mg/g and Iodine number = 1070 mg/g).