Authors: Unai IriarteVelasco Irene Sierra Lorena Zudaire Jose L Ayastuy
Publish Date: 2015/08/06
Volume: 50, Issue: 23, Pages: 7568-7582
Abstract
Microporous biochars mainly composed by hydroxyapatite HAp were prepared from animal waste bones In this study a threestep procedure including prepyrolysis chemical treatment with NaOH KOH and K2CO3 and pyrolysis was investigated The effects of the activation agent and its concentration were analysed by N2 adsorption–desorption SEM EDX FTIR and XRD techniques The activation mechanism was investigated by TGMS FTIR and XRD data confirm that the obtained biochars were mainly composed of HAp K2CO3 was the most effective with porosity being increased by 30 up to 234 m2/g compared to nonalkalitreated sample New pores were generated mainly in the microporous range Analysis of the pyrolysis gases by MS revealed that the main effect of the alkali treatment is the incorporation of OH− ions which then react with bone matrix to generate porosity Other gasphase reactions such as reverse WGS and methanation reactions promoted by K2CO3 may be involved in the activation process In contrast KOH caused little modification of the HAp structure Statistical analysis supported the relationship among the release of certain compounds during pyrolysis and the textural properties of the final material
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