Optimization of pyrolysis conditions for char production from rice husks and its characterization as a precursor for production of activated carbon
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Date
2019-03-13
Journal Title
Journal ISSN
Volume Title
Publisher
Springer
Abstract
Response surface methodology was employed to optimize pyrolysis conditions for the production of char with maximum yield, fixed carbon content, and minimum ash content from Uganda’s New Rice for Africa (NERICA) 1 rice husk variety. The aim was
to obtain rice husk char with more suitable properties as an activated carbon precursor. Mathematical models were developed to
explain the relationships between the experimental responses and the pyrolysis parameters of temperature (400–600 °C), heating
rate (10–25 °C min−1), and heating period (60–120 min). The optimized rice husk char was further characterized for elemental and proximate compositions, thermal behaviour, specific surface area, as well as surface functional groups. Results from the analysis of variance (ANOVA) revealed that the quadratic model best fits each of the responses. Pyrolysis temperature had the
greatest influence on each of the responses, followed by heating period, and lastly heating rate. Optimum pyrolysis conditions
were found to be temperature (406 °C), heating rate (10 °C min−1), and heating period (60 min), resulting in char yield, fixed
carbon, and ash contents of 35.26, 55.39, and 35.01% dry basis, respectively. Compared to raw rice husk, the resulting rice husk
char was found more suited as activated carbon precursor, due to its enriched carbon content (60.35%) and specific surface area
(123.9 m2g−1). Thermogravimetric analysis of the rice husk char revealed that thermal activation temperatures were higher than
400 °C may be required to considerably devolatilize the char, forming a more porous activated carbon.
Description
Keywords
NERICA 1 rice husk ., Pyrolysis ., Optimization ., Char yield ., Fixed carbon ., Ash content