Effects of pyrolysis conditions on the properties of activated carbons prepared from pistachio-nut shells

The feasibility of preparing effective adsorbents from pistachio-nut shell was studied. Optimisation of the pyrolysis conditions prior to activation was carried out to study the effects of pyrolysis temperature, hold time, nitrogen flow rate and heating rate on the properties of chars and activated carbons, whilst the CO2 activation conditions were fixed at a temperature of 900 degreesC, an activation time of 30 min, a heating rate of 10 degreesC/min, a CO2 flow rate of 100 cm(3)/min and a nitrogen flow rate of 150 cm(3)/min. The activated carbons were characterised by a thermo-gravimetric analyser for the proximate analysis, an ultra-pycnometer for the solid density and an accelerated surface area and porosimetry for the determination of the BET and micropore surface areas. The optimum pyrolysis conditions were found to be at a temperature of 500 degreesC for 2 hr hold time, a heating rate of 10 degreesC/min and a nitrogen flow rate of 150cm(3)/min. For these conditions, activated carbons with a maximum BET surface area of 778 m(2)/g were obtained. The experimental results show that activated carbons with a moderate BET surface area can be prepared from pistachio-nut shells. (C) 2004 Elsevier B.V. All rights reserved.