Accepted Manuscript
Preparation and characterization of activated carbon from sunflower seed oil
residue via microwave assisted K2CO3 activation
K.Y. Foo, B.H. Hameed
PII:S0960-8524(11)01093-5
DOI:10.1016/j.biortech.2011.08.007
Reference:BITE 8768
To appear in:Bioresource Technology
Received Date:20 April 2011
Revised Date:24 July 2011
Accepted Date:  2 August 2011
Please cite this article as: Foo, K.Y., Hameed, B.H., Preparation and characterization of activated carb
on from sunflower seed oil residue via microwave assisted K2CO3 activation, Bioresource Technology (2011), doi: 10.1016/ j.biortech.2011.08.007ac reactor
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Preparation and characterization of activated carbon from sunflower seed oil
residue via microwave assisted K2CO3 activation
K.Y. Foo, B.H. Hameed*
School of Chemical Engineering, Engineering Campus,
Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia.
* Corresponding author. Tel: +6045996422; Fax: +6045941013
E-mail address: chbassim@ (B.H. Hameed)
Abstract
Sunflower seed oil residue, a by-product of sunflower seed oil refineries, was utilized as a feedstock for preparation of activated carbon (SSHAC) via microwave induced K2CO3 chemical activation. SSHAC was characterized by Fourier transform infrared spectroscopy, nitrogen adsorption-desorption and elemental analysis. Surface
acidity/basicity was examined with acid-base titration, while the adsorptive properties of SSHAC were quantified using methylene blue (MB) and acid blue 15 (AB). The monolayer adsorption capacities of MB and AB were 473.44 and 430.37 mg/g, while the Brunauer-Emmett-Teller surface area, Langmuir surface area and total pore volume were 1411.55 m2/g, 2137.72 m2/g and 0.836 cm3/g, respectively. The findings revealed the potential to prepare high surface area activated carbon from sunflower seed oil residue by microwave irradiation.
Keywords: Activated carbon; Adsorption; Dye; Microwave; Sunflower seed hull
1.0Introduction
Sunflower (Helianthus annuus L.) is one of the leading oil seed crops cultivated for the production of cooking oil. The oil is typically extracted by applying great pressure to sunflower seeds (Séverac et al., 2011). Globally, sunflowers are grown on about 24 million hectars, and 32.57 million tons of sunflower seeds were produced globally in 2009/2010 (National Sunflower Association, 2011). Oil extraction from the seeds is accompanied by the co-production of lignocellulosic biomass, in the form of sunflower seed hulls, which comprises 30 % of the sunflower seeds (Ra et al., 2008). These residues are usually disposed of by burning or by deposition in landfills, but conversion to higher-value products would be preferable. One such product could be activated carbon (Girgis et al., 2011; Li et al., 2011a; Liou et al., 2010). The present study was aimed at evaluating microwave irradiation for the preparation of high surface area activated carbon from sunflower seed hulls (SSHAC), via K2CO3 activation. Structural, functional and elemental characterization of the prepared adsorbent was performed. Moreover, the adsorption equilibrium of methylene blue and acid blue 15 were elucidated.
2. 0  Materials and methods
2.1 Adsorbate
Methylene blue (MB) and acid blue 15 (AB) were from Merck Limited Company, Malaysia. Stock solutions containing 500 mg/L of dye were prepared in double distilled
water and diluted as necessary.
2.2.  Preparation of SSHAC
Sunflower seed hulls (SSH) obtained from sunflower seed oil refineries were air-dried, crushed and sieved to obtain a geometrical mean sizes ranging from 1 to 2 mm, and carbonized at 700 °C under purified nitrogen (99.995%) flow in a tubular furnace (Foo and Hameed, 2011). The char was mixed with potassium carbonate (K2CO3) solution to achieve an impregnation ratio of 1: 1.50 (wt %) (K2CO3: char). The activation step was performed in a glass reactor placed in a microwave oven with a frequency of 2.45 GHz. The microwave power was set as 600 W and 8 minutes of irradiation time was selected as the heating period based on preliminary runs. The activated product was washed with 0.1 N hydrochloric acid and deionized water until the pH of the washing solution reached 6 to 7.
2.3 Characterization of SSHAC
The surface physical properties were characterized with a Micromeritics ASAP 2020 instrument, using N2 as the adsorbate at 77 K. Detection of surface functional groups and elemental analysis were done by Fourier transform infrared (FTIR) spectroscopy (FTIR-2000, PerkinElmer) with a scanning range of 4000 to 400 cm-1 and elemental analyzer (EA-2400 Series II, PerkinElmer), respectively.
2.4  Surface acidity and basicity
where C0 and C e (mg/L) are the liquid-phase concentrations of dye at initial and equilibrium, respectively. V (L)is the volume of the solution, and W (g)is the mass of

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