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Kinetic study on phosphate removal from aqueous solution by biochar derived from peanut shell as renewable adsorptive media
Jung, K.-W.; Hwang, M.-J.; Ahn, K.-H. & Ok, Y.-S.
Abstract
As an alternative strategy for phosphate
removal, biochar (black carbon) has characteristics superior
to those of widely used adsorptive media, from both
economic and environmental points of view. In this study,
various types of biochar derived from oak wood, bamboo
wood, maize residue, soybean stover, and peanut shell were
tested for evaluation of phosphate removal. After 24 h
of reaction time, the phosphate removal was limited
(2.0–9.4 %) in case of general adsorptive media. However,
interestingly, among various biochars, peanut shell-derived
biochar (PSB) exhibited the best performance, showing the
highest phosphate removal rate, 61.3 % (3.8 mg PO4-P g
PSB-1). We attribute this high value to the proper structural
properties of PSB, such as BET-specific surface area
of 348.96 m2 g-1 and mineral/phosphorus ratio (Mg/
P = 3.46 and Ca/P = 47.6). Adsorption equilibrium and
kinetics of phosphate at different temperature (10, 20, and
30 °C) were well explained in the whole experimental
region by Langmuir isotherm and pseudo-second-order
kinetic models, respectively. The maximum adsorption
capacity of PSB was 6.79 mg g-1 for phosphate at 30 °C.
These findings suggest that PSB has great potential as an
alternative and renewable adsorptive media for phosphate
removal.
Keywords
Phosphate removal; Biochar; Black carbon; Charcoal; Peanut shells; Mineral/phosphorus ratio
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