Surface functional groups on acid-activated nutshell carbons

Nutshells from agriculturally important nut crops (almond, black walnut, En glish walnut, macadamia nut and pecan) were converted to granular activated carbon using phosphoric acid activation in nitrogen or air. Surface functi onal groups (carbonyl, phenols, lactones, carboxyl) were quantified by titr ation with bases of different ionization potential. The degree of copper up take was correlated with the presence of various functional groups on these carbons. The results indicate that acid-activation strategies which provid e the greatest contact of nutshells with air during carbonization and activ ation also have the greatest quantity of surface functional groups and the highest copper uptake. Also, the type of nutshell used for activated carbon production has little effect on the types of surface functional groups pro duced and subsequent copper adsorption. This study demonstrates that a judi cious choice of activation strategy for nutshell precursors can produce act ivated carbons with numerous surface functional groups and high copper adso rption activity. (C) 1999 Published by Elsevier Science Ltd. All rights res erved.